An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces and may be part of the normal skin flora of humans. Causes hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter calcoaceticus

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces and may be part of the normal skin flora of humans. Causes hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter calcoaceticus genospecies 2 (Acinetobacter baumanii)

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces and may be part of the normal skin flora of humans. Causes hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter calcoaceticus genospecies 3

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces and may be part of the normal skin flora of humans. Causes hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter calcoaceticus genospecies 13 (Acinetobacter baumanii)

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces and may be part of the normal skin flora of humans. Causes hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter genospecies 10 (Acinetobacter calcoaceticus biotype lwoffii)

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces. It may cause hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter genospecies 15

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces and may be part of the normal skin flora of humans. Causes hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter johnsonii (Acinetobacter calcoaceticus biotype lwoffii)

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces. It may cause hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter johnsonii genospecies 7 (Acinetobacter calcoaceticus biotype lwoffii)

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces. It may cause hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter lwoffii (Acinetobacter calcoaceticus biotype lwoffii)

An aerobic gram-negative bacillus widely distributed in nature (soil, sewage, and water) and in the hospital environment. It is able to survive on both moist and dry surfaces and may be part of the normal flora of humans. Causes hospital-acquired respiratory, urinary tract, wound infections, abscesses, and meningitis in debilitated humans.

Acinetobacter radioresistens

An aerobic gram-negative bacillus occasionally isolated from environmental sources. It is able to survive on both moist and dry surfaces. It has not been reported as a cause of human infections.

Acinetobacter radioresistens genospecies 12

An aerobic gram-negative bacillus occasionally isolated from environmental sources. It is able to survive on both moist and dry surfaces. It has not been reported as a cause of human infections.

Aerobic Actinomycetales

The aerobic Actinomycetales represent a group of gram-positive organisms that range from aerobic gram-positive bacilli (diphtheroids) to branching, filamentous gram-positive bacteria. Some genera are capable of forming well-developed aerial and vegetative branched filaments. Genera include: Nocardia, Streptomyces, Mycobacterium, Actinomadura, Nocardiopsis, Rhodococcus, Micromonospora, Oerskovia, Saccharomonospora, Saccharopolyspora, Tsukamurella, Thermoactinomyces and Dermatophilus. The genera Saccharomonospora, Saccharopolyspora, and Thermoactinomyces are considered thermophilic actinomycetes because of their ability to grow at 50oC (122oF). The aerobic Actinomycetales have been isolated from the skin, pharynx and gastrointestinal tract of humans and animals and from soil, beach sand, house dust, tap water, swimming pools, plants, compost, hay, decaying vegetation, manure, air-conditioning ducts and humidifier water. They cause human infections following inhalation of these bacteria or by contamination of an area of trauma.

Aeromonas species

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fishes, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Aeromonas caviae DNA group 4

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fish, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Aeromonas hydrophilia DNA group 1

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fish, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Aeromonas media DNA group 5B

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fish, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Aeromonas media-like, DNA group 5A

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fish, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Aeromonas salmonicida

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fish, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Aeromonas schubertii DNA Group 12

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fish, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Aeromonas veronii / sorbria DNA group 8

An aerobic, oxidase-positive, gram-negative bacillus indigenous to the aquatic environment. They are found in freshwater, chlorinated water, polluted water, brackish water, estuarine water, and sewage. They are associated with a wide variety of diseases in warm and cold blooded vertebrates including frogs, fish, reptiles, snakes, birds and rarely in humans. They are capable of causing gastroenteritis and wound infections in humans, especially those individuals with liver disease.

Agrobacterium species

An aerobic, oxidase-positive, gram-negative bacillus that produces nonpigmented to light beige colonies. Some colonies may be mucoid due to the production of a slime capsule by the organism. It is isolated from plants and soil. It is primarily a plant pathogen and has not been reported as a cause of human infections.

Agrobacterium radiobacter (CDC Group Vd-3)

An aerobic, oxidase-positive, gram-negative bacillus that produces nonpigmented to light beige colonies. Some colonies may be mucoid due to the production of a slime capsule by the organism. It is isolated from plants and soil. It is primarily a plant pathogen. It has been isolated from clinical specimens but is rarely reported as the cause of human infections.

Agrobacterium rhizogenes

An aerobic, oxidase-positive, gram-negative bacillus that produces nonpigmented to light beige colonies. Some colonies may be mucoid due to the production of a slime capsule by the organism. It is isolated from plants and soil. It is primarily a plant pathogen and has not been reported as a cause of human infections.

Agrobacterium rhizogenes A

An aerobic, oxidase-positive, gram-negative bacillus that produces nonpigmented to light beige colonies. Some colonies may be mucoid due to the production of a slime capsule by the organism. This isolate of A. rhizogenes has been identified as belonging to Group A using the Biolog classification system. It is isolated from plants and soil. It is primarily a plant pathogen and has not been reported as a cause of human infections.

Agrobacterium tumefaciens

An aerobic, oxidase-positive, gram-negative bacillus that produces nonpigmented to light beige colonies. Some colonies may be mucoid due to the production of a slime capsule by the organism. It is isolated from plants and soil. It is primarily a plant pathogen and has not been reported as a cause of human infections.

Agrobacterium tumefaciens A

An aerobic, oxidase-positive, gram-negative bacillus that produces nonpigmented to light beige colonies. Some colonies may be mucoid due to the production of a slime capsule by the organism. This isolate of A. tumefaciens has been identified as belonging to Group A using the Biolog classification system. It is isolated from plants and soil. It is primarily a plant pathogen and has not been reported as a cause of human infections.

Agrobacterium vitis

An aerobic, oxidase-positive, gram-negative bacillus that produces nonpigmented to light beige colonies. Some colonies may be mucoid due to the production of a slime capsule by the organism. It is isolated from plants and soil. It is primarily a plant pathogen and has not been reported as a cause of human infections.

Alcaligenes species

An aerobic, oxidase-positive, gram-negative bacillus commonly found in the environment. It is a common inhabitant of the intestinal tract of vertebrates, nematodes, and insects. It can be isolated from soil, fresh water, salt water, dairy products and rotten eggs. It rarely causes disease in humans.

Alcaligenes faecalis

An aerobic, oxidase-positive, gram-negative bacillus commonly found in the environment. It is a common inhabitant of the intestinal tract of vertebrates, nematodes, and insects. It can be isolated from soil, fresh water, salt water, dairy products and rotten eggs. It rarely causes disease in humans.

Alcaligenes faecalis sub-species homari

An aerobic, oxidase-positive, gram-negative bacillus commonly found in the marine environment. It is found in salt water and is a shellfish pathogen but does not cause disease in humans.

Alcaligenes latus

An aerobic, oxidase-positive, gram-negative bacillus which produces wrinkled, greyish-pink colonies. It can be isolated from soil. It has not been isolated from humans.

Alcaligenes xylosoxidans subspecies xylosoxidans (Achromobacter xylosoxidans)

An aerobic, oxidase-positive, gram-negative bacillus that is widely distributed in the environment. It is part of the normal bacterial flora of the intestinal tract of vertebrates. It can be isolated from soil, fresh water, salt water, and dairy products. It can be an human opportunistic pathogen.

Alcaligenes xylosoxidans subspecies denitrificans (Achromobacter denitrificans)

An aerobic, oxidase-positive, gram-negative bacillus that is widely distributed in the environment. It is part of the intestinal tract of vertebrates. It can be isolated from soil, fresh water, salt water, and dairy products. It rarely causes disease in humans.

Aquaspirillum species

An aerobic, oxidase-positive, gram-negative curved or spiral-shaped bacteria that can be isolated from fresh water. It does not cause disease in humans.

Aquaspirillum peregrinum

An aerobic, oxidase-positive, gram-negative curved or spiral-shaped bacteria that can be isolated from fresh water. It does not cause disease in humans.

Arthrobacter species

An aerobic gram-positive bacillus commonly found in the environment especially in soil. It rarely may be an opportunistic pathogen.

Aureobacterium species

An aerobic gram-positive bacillus which produces yellow to orange-red colonies. It can be isolated from soil and plants. It has not been isolated from humans.

Aureobacterium terregens

An aerobic gram-positive bacillus which produces yellow to orange-red colonies. It can be isolated from soil and plants. It has not been isolated from humans.

Aureobacterium testaceum

An aerobic gram-positive bacillus which produces yellow to orange-red colonies. It can be isolated from soil and plants. It has not been isolated from humans.

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Bacillus species

A large aerobic, gram-positive, gram-variable, or rarely gram-negative bacillus that produces endospores. Colonies appearing on agar medium may be smooth, wrinkled, mucoid, or may have hair-like outgrowths from the edge. They are ubiquitous in nature being found in soil, dust, water, plants, humans and animals. The majority of species are nonpathogenic or opportunistic pathogens for humans. Exceptions are Bacillus anthracis, the cause of anthrax, and Bacillus cereus as an agent of food poisoning. Several species are plant and insect pathogens

Bacillus alcalophilus

A large aerobic gram-positive or gram-variable bacillus that produces endospores. Produces thin colonies on agar medium. It can be isolated from soil (especially in alkaline soil), dust, water, and sewage. It has not been isolated from humans.

Bacillus amyloliquefaciens

A large aerobic, gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium may be smooth or wrinkled. It is commonly isolated from soil, dust, water, and plants. It has not been isolated from humans.

Bacillus (Paenibacillus) azotoformans

A large aerobic, gram-negative or gram-variable, rarely gram-positive bacillus that produces endospores. Colonies appearing on agar medium are smooth and translucent. It is isolated from soil, dust, and plants. It has not been isolated from humans.

Bacillus brevis

A large aerobic, gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium may be smooth, or may have hair-like outgrowths endospores and appears in chains. Colonies appearing on agar medium may be smooth, or may have hair-like outgrowths from the edge. It is ubiquitous in nature being found in soil, dust, water, plants, humans and animals. It can cause food poisoning in humans and animals. Usually considered nonpathogenic for humans, but may occasionally be an opportunistic pathogen.

Bacillus circulans

A large aerobic, gram-positive or gram-variable bacillus that produces endospores. It is a thermotolerant bacterium, capable of growth at 50oC (122oF). It is isolated primarily from soil. Usually considered nonpathogenic for humans but may cause wound infections, septicemia, and rarely meningitis.

Bacillus coagulans

A large aerobic, gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium are highly variable (smooth, wrinkled, rough, or may have hair-like outgrowths from the edge. It is isolated primarily from acid foods (canned tomato juice and silage), medicated creams, antacids and rarely from soil. Usually considered nonpathogenic for humans, but may occasionally be an opportunistic pathogen.

Bacillus laevolacticus

A large aerobic, gram-positive or gram-variable bacillus that produces endospores. It is found in soil and plants. Considered nonpathogenic for humans.

Bacillus lentus

A large aerobic, gram-positive or gram-variable bacillus that produces endospores. It is found in soil. Considered nonpathogenic for humans.

Bacillus licheniformis

A large aerobic, gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium may be smooth, or may have hair-like outgrowths from the edge. It is ubiquitous in nature being found in soil, dust, water, plants, humans and animals. Usually considered nonpathogenic for humans, but may occasionally be an opportunistic pathogen.

Bacillus (Paenibacillus) macerans

A large aerobic, gram-negative, rarely gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium are usually thin and spreading. It can be isolated from plants, canned fruits, and rarely from soil. Usually considered nonpathogenic for humans.

Bacillus megaterium

A large aerobic, gram-negative, rarely gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium are usually smooth. It is ubiquitous in nature being found in soil, dust, water, plants, humans and animals. Usually considered nonpathogenic for humans, but may occasionally be an opportunistic pathogen.

Bacillus mycoides

A large aerobic, gram-negative, rarely gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium are distinctive rhizoid. It is ubiquitous in nature being found in soil, dust, water, plants, humans and animals. Usually considered nonpathogenic for humans.

Bacillus pasteurii

A large aerobic gram-positive or gram-variable bacillus that produces endospores. It produces thin colonies on agar medium with amoeboid spreading or may be mucoid. It is ubiquitous in nature being found in soil, dust, water, sewage, and encrustation on urinals. Usually considered nonpathogenic for humans.

Bacillus (Paenibacillus) polymyxa

A large aerobic gram-positive or gram-variable bacillus that produces endospores. It produces thin colonies on agar medium with amoeboid spreading or may be mucoid. It is ubiquitous in nature being found in soil, dust, water, plants, humans and animals. Usually considered nonpathogenic for humans, but may occasionally be an opportunistic pathogen.

Bacillus pumilus

A large aerobic gram-positive or gram-variable bacillus that produces endospores. It produces very variable colonies on agar medium. It is ubiquitous in nature being found primarily in soil. Usually considered nonpathogenic for humans.

Bacillus sphaericus

A large aerobic gram-positive or gram-variable bacillus that produces endospores. It produces compact and heaped colonies or colonies that spread over the agar surface. Rarely, may produce a pink colony. It is ubiquitous in nature being found in soil, fresh and salt water sediments, milk, foods, and antacids. Usually considered nonpathogenic for humans, but may occasionally be an opportunistic pathogen.

Bacillus subtilis

A large aerobic gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium may be smooth or wrinkled. It is ubiquitous in nature being found in soil, dust, water, plants, humans and animals. It is nonpathogenic or may occasionally be an opportunistic pathogen for humans.

Bacillus subtilis variety globigii

A large aerobic gram-positive or gram-variable bacillus that produces endospores. Colonies appearing on agar medium may be smooth or wrinkled. It is ubiquitous in nature being found in soil, dust, water, plants, humans and animals. It is nonpathogenic or rarely an opportunistic pathogen for humans.

Bacillus thuringiensis

A large aerobic gram-positive or gram-variable bacillus that produces endospores. It produces a crystalline protein body pathogenic for the larvae of Lepidoptera. It is used as a biological insecticide. It is an opportunistic pathogen for humans.

Brevibacterium species

An aerobic, nonsporeforming, short, gram-positive bacillus that produces brownish, yellow, or orange colonies. It has been isolated from dairy products, fresh and salt water, insects, soil, sewage, fruits, vegetables, and rice paddies. It has not been isolated from humans.

Brevibacterium acetylicum

An aerobic, nonsporeforming, short, gram-positive bacillus that produces flat, yellow-orange colonies. It has been isolated from dairy products, but has not been isolated from humans.

Brevundimonas species (Pseudomonas species)

An aerobic, oxidase-positive, gram-negative bacillus that produces yellow or orange colonies. It is rarely isolated from environmental specimens (water) and clinical specimens (blood).

Brevundimonas diminuta (Pseudomonas diminuta)

An aerobic, oxidase-positive, gram-negative bacillus that produces yellow or orange colonies. It is rarely isolated from environmental specimens (water) and clinical specimens (blood).

Brevundimonas vesicularis (Pseudomonas vesicularis)

An aerobic, oxidase-positive, gram-negative bacillus that produces yellow or orange colonies. It is rarely isolated from environmental specimens (water) and clinical specimens (blood).

Burkholderia species

An aerobic gram-negative bacillus widely distributed in water, soil and plants, including fruits and vegetables. It is a well recognized plant pathogen and some species are capable of causing nosocomial infections associated with contaminated water (including flower vases), disinfections, equipments and medications. One species, B. cepacia, is an important pathogen in persons with cystic fibrosis and chronic granulomatous disease.

Burkholderia cepacia

An aerobic gram-negative bacillus widely distributed in water, soil and plants, including fruits and vegetables. It is a well recognized nosocomial pathogen causing infections associated with contaminated water (including flower vases), disinfections, equipments and medications. It is an important pathogen in persons with cystic fibrosis and chronic granulomatous disease.

Burkholderia covovenenans

An aerobic gram-negative bacillus widely distributed in water, soil and plants, including fruits and vegetables. It is a well recognized plant pathogen. There have not been any reports of human infections.

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CDC Groups

A member of a CDC (Center for Disease Control) Group is an organism that does not have genus status as yet. Primarily this is because the isolate has been rarely isolated and more isolates are required before the necessary biochemical reactions for genus status can be determined They may be either gram-positive or gram-negative bacteria.

CDC Group B - 1/B - 3

An aerobic gram-positive coccus that produces a yellow pigmented colony. It is rarely isolated from the environment. There have not been any reports of human infections.

CDC Group DF - 3

An aerobic gram-negative bacillus coccus that is rarely isolated from the environment. There have not been any reports of human infections.

CDC Group E

A small aerobic, gram- positive, bacillus that produces a small cream to white colony. It is rarely isolated from the environment. There have not been any reports of human infections.

CDC Group E, Subgroup A

A small aerobic, gram- positive, bacillus that produces a small cream to white colony. It is rarely isolated from the environment. There have not been any reports of human infections.

CDC Group EF - 4

A small aerobic, oxidase positive, gram-negative bacillus that produces a small white colony. It is part of the normal oral flora of humans and animals. It is rarely isolated from environmental samples. It is nonpathogenic or rarely an opportunistic pathogen for humans.

CDC Group EO - 2 (Eugonic Oxidizer - 2)

An aerobic, oxidase positive, gram-negative bacillus that produces a light yellowish colony. It has been isolated from air, soil, and clinical specimens, but have not been reported as the cause of any human infections.

CDC Group II - H

An aerobic, oxidase positive, gram-negative bacillus that produces a tan to brown colony. It has been isolated from soil, plants, foodstuffs and water. There have not been any reports of human infections.

CDC Group II - I

An aerobic, oxidase positive, gram-negative bacillus that produces a tan to slightly yellow pigmented colony. It has been isolated from soil, plants, foodstuffs and water. There have not been any reports of human infections.

CDC Group IVc - 2

An aerobic, oxidase positive, gram-negative bacillus that produces a gray to cream colony. It has been isolated from a variety of human sources and can cause septicemia and peritonitis.

Cellulomonas cartae

An aerobic, gram-positive bacillus that produces a yellow pigmented colony. It is found in soil and has not been associated with infections in man.

Chryseobacterium indologenes (Flavobacterium indologenes, Flavobacterium Group IIb)

An aerobic, oxidase-positive, indole-positive, gram-negative bacillus that produces a bright yellow pigmented colony. They are found in raw meat, poultry, vegetables, dairy products, soil and water. A significant source of infections include heated and unheated nebulizers, water baths, sink faucets, distilled water lines, dental chair spray units, and cold humidifiers. Rarely associated with nosocomial (hospital-acquired) infections in man.

Chryseobacterium meningosepticum (Flavobacterium meningosepticum)

An aerobic, oxidase-positive, gram-negative bacillus that produces a slight yellow pigmented colony. The natural habitat is soil and water. A significant source of infections include heated and unheated nebulizers, water baths, sink faucets, distilled water lines, dental chair spray units, and cold humidifiers. Associated with epidemic situations involving outbreaks of meningitis in hospital neonatal nurseries.

Chryseomonas luteola (Group Ve - 1)

An aerobic, oxidase-negative, gram-negative bacillus that produces a yellow pigmented colony. It is widely distributed in both nature and the hospital environment. It has been associated with nosocomial infections in man.

Citrobacter species

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth colony. It is part of the normal intestinal flora of humans and animals and can be isolated from soil, water, sewage, and food. It is an opportunistic pathogen for humans causing both diarrhea and extra intestinal infections (meningitis, abscesses, and septicemia).

Citrobacter amalonaticus

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth colony. It is part of the normal intestinal flora of humans and animals and is isolated from soil, water, sewage, and food. It is an opportunistic pathogen for humans causing extra intestinal infections (meningitis, abscesses, and septicemia) but probably does not cause diarrhea.

Citrobacter freundii

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth colony. It is part of the normal intestinal flora of humans and animals and is isolated from soil, water, sewage, and food. It is an opportunistic pathogen for humans.

Citrobacter koserii (Citrobacter diversus)

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth colony. It is part of the normal intestinal flora of humans and animals and is isolated from soil, water, sewage, and food. It is an opportunistic pathogen for humans causing both diarrhea and extra intestinal infections (meningitis, abscesses, and septicemia).

Clavibacter species

An aerobic, nonsporeforming, gram-positive bacillus that produces white, yellow, orange and pink colonies. It is primarily a plant pathogen and has not been isolated from humans.

Clavibacter michiganense (Clavibacter michiganense subspecies michiganense) (Corynebacterium michiganense)

An aerobic, nonsporeforming, gram-positive bacillus that produces white, yellow, orange and pink colonies. It is primarily a plant pathogen and has not been isolated from humans.

Clavibacter sepedonicum (Clavibacter michiganense subspecies sepedonicum) (Corynebacterium sepedonicum)

An aerobic, nonsporeforming, gram-positive bacillus that produces off-white or pale yellow colonies. It is primarily a plant pathogen and has not been isolated from humans.

Coagulase negative staphylococci

Coagulase negative staphylococci (CNS) are gram-positive cocci that make up the majority of bacterial organisms that are part of the normal flora of the skin, skin glands, and mucous membranes of humans, animals, and birds. They can be isolated from dairy products and food. They are opportunistic pathogens in humans, animals, and birds.

Coagulase positive staphylococci

Coagulase positive staphylococci are gram-positive cocci that can be found on the skin and mucous membranes of humans and animals. They are a potential pathogen for humans and animals.

Comamonas species

An aerobic, oxidase-positive, gram-negative bacillus that has been isolated from soil and rarely from clinical specimens. Causes infections in certain populations of humans, especially in compromised or debilitated individuals.

Comamonas acidovorans (Pseudomonas acidovorans)

An aerobic, oxidase-positive, gram-negative bacillus that has been isolated from soil and rarely from clinical specimens. Causes infections in certain populations of humans, especially in compromised or debilitated individuals.

Comamonas terrigena (Vibrio neocistes)

An aerobic, oxidase-positive, gram-negative bacillus that has been isolated from soil, water, and plants. It has not been reported as a cause of human infections.

Commonas testosteroni (Pseudomonas testosteroni)

An aerobic, oxidase-positive, gram-negative bacillus that has been isolated from soil and water. It is rarely from clinical specimens.

Corynebacterium species

Aerobic, nonsporeforming, gram-positive bacilli that are straight, curved, and club-shaped. They are often seen on Gram stain in a palisade arrangement producing Xs, Y, and AChinese letters@. They produce white, yellow, cream, or gray colored colonies. They can be isolated from humans, warm-blooded animals, plants and foodstuffs. The majority are plant and animal pathogens. A few species are capable of causing disease in humans.

Corynebacterium afermentans (CDC Group ANF - 1)

An aerobic, nonsporeforming, gram-positive coccobacillus that produces cream or white colonies. It has been isolated from plants and human skin. It is not pathogenic for humans.

Corynebacterium aquaticum

An aerobic, nonsporeforming, gram-positive coccobacillus that produces lemon yellow colonies. It has been isolated from distilled and fresh water. It can be a potential pathogen for humans.

Corynebacterium aquaticum A

An aerobic, nonsporeforming, gram-positive coccobacillus that produces lemon yellow colonies. This isolate has been identified as belonging to Group A using the BiologJ classification system. It has been isolated from distilled and fresh water. It can be a potential pathogen for humans.

Corynebacterium aquaticum B

An aerobic, nonsporeforming, gram-positive coccobacillus that produces lemon yellow colonies. This isolate has been identified as belonging to Group B using the BiologJ classification system. It has been isolated from distilled and fresh water. It can be a potential pathogen for humans.

Corynebacterium jeikeium

An aerobic, nonsporeforming, gram-positive coccobacillus that produces gray colonies. It has been isolated from air, environmental surfaces, and human skin. It has been reported as causing infections in patients who are immunocompromised, have received medical devices (e.g., vascular or implanted access catheters), have been hospitalized for prolong periods, or have received prolonged antimicrobial therapy. It resistant to multiple antibiotics.

Corynebacterium jeikeium A

An aerobic, nonsporeforming, gram-positive coccobacillus that produces gray colonies. This isolate has been identified as belonging to Group A using the BiologJ classification system. It has been isolated from air, environmental surfaces, and human skin. It has been reported as causing infections in patients who are immunocompromised, have received medical devices (e.g., vascular or implanted access catheters), have been hospitalized for prolong periods, or have received prolonged antimicrobial therapy. It resistant to multiple antibiotics.

Corynebacterium jeikeium B

An aerobic, nonsporeforming, gram-positive coccobacillus that produces gray colonies. This isolate has been identified as belonging to Group B using the BiologJ classification system. It has been isolated from air, environmental surfaces, and human skin. It has been reported as causing infections in patients who are immunocompromised, have received medical devices (e.g., vascular or implanted access catheters), have been hospitalized for prolong periods, or have received prolonged antimicrobial therapy. It resistant to multiple antibiotics.

Corynebacterium pseudodiphtheriticum

An aerobic, nonsporeforming, gram-positive coccobacillus that produces white to cream colonies. It has been isolated as part of the normal skin and oropharyngeal flora in humans. It has been reported as causing septicemia, respiratory infections and urinary tract infections in humans.

Curtobacterium species

An aerobic, nonsporeforming, gram-positive bacillus that produces white, yellow, orange and pink colonies. It has been isolated from plants and oil brine. It is pathogenic only for plants. There have not been any reports of human infections.

Curtobacterium albidum

An aerobic, nonsporeforming, gram-positive bacillus that produce white colonies. It has been isolated from plants but it is not a plant pathogen. There have not been any reports of human infections.

Curtobacterium citreum

An aerobic, nonsporeforming, gram-positive bacillus that produce dull yellow colonies. It has been isolated from plants but it is not a plant pathogen. There have not been any reports of human infections.

Curtobacterium flaccumfaciens

An aerobic, nonsporeforming, gram-positive bacillus that produces yellow, orange and pink colonies. It has been isolated from plants and is a plant pathogen. There have not been any reports of human infections.

Curtobacterium luteum

An aerobic, nonsporeforming, gram-positive bacillus that produces yellow colonies. It has been isolated from plants but is not a plant pathogen. There have not been any reports of human infections.

Cytophaga johnsonae (Flavobacterium pectinovorum)

An aerobic, oxidase-positive, gram-negative bacillus that produces a yellow pigmented colony. Their natural habitat is soil and plants. There have not been any reports of human infections.

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Dermabacter hominis

An aerobic, gram-positive bacillus that is found on mammalian skin. There have not been any reports of human infections.

Dermacoccus nishinomiyaensis (Micrococcus nishinomiyaensis)

An aerobic, gram-positive or gram-variable coccus occurring in pairs, tetrads (groups of four) or irregular clusters of tetrads with bright orange colonies. They are found on mammalian skin and in water. The majority of strains are nonpathogenic for humans.

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Enterobacter species

An aerobic gram-negative bacillus that grows readily on most microbiological media. It produces white or bright to light yellow pigmented colonies that have either a smooth, mucoid, rubbery, rough or dry consistency. Isolates from environmental sources grow best at 20oC to 30oC while isolates from clinical sources grow best at 35oC. They are part of the normal intestinal flora of humans and animals. They have been isolated from soil, water, sewage vegetables, meats, plants, flowers, seeds, dairy products, and cosmetics. They are important causes of nosocomial (hospital-acquired) infections especially in immunologically compromised humans.

Enterobacter aerogenes

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a white colony with either a smooth or a mucoid consistency. It is part of the normal intestinal flora of humans and animals and has been isolated from soil, water, sewage, meat and the hospital environment. It is capable of causing infections in humans especially in immunocompromised patients. It is an important cause of nosocomial (hospital-acquired) infections.

Enterobacter agglomerans

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a yellow colony with either a smooth, rough or mucoid consistency. It can be isolated from plants, flowers, seeds, soil, water, and foodstuffs. It is capable of causing infections in immunologically compromised patients (neonates, premature infants, burned or multiple traumatized patients, patients receiving immunosuppressive therapy, or patients with leukemia).

Enterobacter agglomerans biogroup 2A

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a yellow colony with either a smooth, rough or mucoid consistency. This isolate has been identified as belonging to biogroup 2A using the Biolog classification system. It can be isolated from plants, flowers, seeds, soil, water, and foodstuffs. It is capable of causing infections in immunologically compromised patients (neonates, premature infants, burned or multiple traumatized patients, patients receiving immunosuppressive therapy, or patients with leukemia).

Enterobacter agglomerans biogroup 3B

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a yellow colony with either a smooth, rough or mucoid consistency. This isolate has been identified as belonging to biogroup 3B using the Biolog classification system It can be isolated from plants, flowers, seeds, soil, water, and foodstuffs. It is capable of causing infections in immunologically compromised patients (neonates, premature infants, burned or multiple traumatized patients, patients receiving immunosuppressive therapy, or patients with leukemia).

Enterobacter amnigenus

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth, white colony. It can be isolated from drinking and surface water, and soil. It has not been reported as causing infections in humans and animals.

Enterobacter asburiae

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a non-pigmented colony. It has been isolated environmentally from water and clinically from specimens of urine, respiratory sources, stools, wounds and blood. It is capable of causing infections in humans, especially in immunocompromised patients.

Enterobacter cloacae

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a white colony with either a smooth or a mucoid consistency. It is the most frequent Enterobacter species isolated from humans and animals. It is part of the normal intestinal flora of humans and animals and has been isolated from soil, water, sewage, meat and the hospital environment.. It is capable of causing infections in humans (meningitis, septicemia, abscesses), especially in debilitated individuals. It is an important cause of nosocomial (hospital-acquired) infections.

Enterobacter gergoviae

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth white colony. It has been isolated from cosmetics, water and from clinical specimens (urine, sputum, blood, and wound and abscess drainage. It is an important cause of nosocomial (hospital-acquired) urinary tract infections.

Enterobacter intermedium

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth, white colony. It can be isolated from drinking and surface water, and soil. It is not been reported as causing infections in humans and animals.

Enterobacter sakazakii

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a bright to light yellow colony with either a smooth, mucoid, rubbery, or dry consistency. It occurs in the environment and in food but rarely in clinical specimens. It is capable of causing neonatal meningitis and septicemia

Enterococcus faecalis

An aerobic, gram-positive coccus occurring in pairs and short chains producing either gray or off-white colonies. The primary habitat is the gastrointestinal tract of man, animals, and insects, and on plants. Causes urinary tract infections, subacute bacterial endocarditis, and is an important cause of postoperative wound infections.

Escherichia coli

An aerobic gram-negative bacillus that grows readily on most microbiological media. It is part of the normal intestinal flora of humans and animals and have been isolated from soil, water and sewage. It is an opportunistic pathogen for humans and animals.

Ewingella americana

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a yellow colony with a smooth consistency. This organism was previously classified in the Enterobacter agglomerans complex. It has been isolated from human sputum, blood, and wounds. It is capable of causing infections in immunologically compromised patients (neonates, premature infants, burned or multiple traumatized patients, patients receiving immunosuppressive therapy, or patients with leukemia).

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Flavimonas oryzihabitans (CDC Group Ve-2, Pseudomonas oryzihabitans)

An aerobic, oxidase-negative, gram-negative bacillus that produces a yellow pigmented colony. It is widely distributed in both nature and the hospital environment. It has been associated with nosocomial (hospital-acquired) infections in man.

Flavobacterium species

An aerobic, oxidase-positive, gram-negative bacillus that produces a bright yellow pigmented colony. They are found in raw meat, poultry, vegetables, dairy products, soil and water. A significant source of infections include heated and unheated nebulizers, water baths, sink faucets, distilled water lines, dental chair spray units, and cold humidifiers. Flavobacteria are rarely isolated from humans. They have been associated with epidemic situations involving outbreaks of meningitis in hospital neonatal nurseries.

Flavobacterium balustinum

An aerobic, oxidase-positive, gram-negative bacillus that produces a viscous, bright yellow pigmented colony. The natural habitat is soil, plants and water. There have not been any reports of human infections.

Flavobacterium breve

An aerobic, oxidase-positive, gram-negative bacillus that produces a light yellow pigmented colony. The natural habitat is soil, water, and sewage. There have not been any reports of human infections.

Flavobacterium gleum (Flavobacterium Group IIb)

An aerobic, oxidase-positive, gram-negative bacillus that produces a yellow to yellow-orange pigmented colony. The natural habitat is soil, plants and water. There have not been any reports of human infections.

Flavobacterium indologenes (Flavobacterium Group IIb)

An aerobic, oxidase-positive, indole-positive, gram-negative bacillus that produces a bright yellow pigmented colony. They are found in raw meat, poultry, vegetables, dairy products, soil and water. A significant source of infections include heated and unheated nebulizers, water baths, sink faucets, distilled water lines, dental chair spray units, and cold humidifiers. Rarely associated with nosocomial (hospital-acquired) infections in man.

Flavobacterium indoltheticum

An aerobic, oxidase-positive, indole-positive, gram-negative bacillus that produces a bright yellow pigmented colony. It has been isolated from air, plants, soil and water. There have not been any reports of human infections.

Flavobacterium meningosepticum

An aerobic, oxidase-positive, gram-negative bacillus that produces a slight yellow pigmented colony. The natural habitat is soil and water. A significant source of infections include heated and unheated nebulizers, water baths, sink faucets, distilled water lines, dental chair spray units, and cold humidifiers. Associated with epidemic situations involving outbreaks of meningitis in hospital neonatal nurseries.

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Gilardi Pink Gram Negative Bacillus

An aerobic, oxidase-positive, gram-negative bacillus that produces a pinkish colony. It is rarely isolated from environmental sources and human clinical infections.

Gluconobacter oxydans subspecies suboxydans (Gluconobacter cerinus)

An aerobic, oxidase-negative, gram-negative bacillus that produces a white to yellowish colony. It has been isolated from flowers, souring fruits, vegetables, beer, cider, wine, baker=s yeast and garden soil. There have not been any reports of human infections.

Gordonia species

An aerobic, gram-positive bacterium with some branching filaments. It produces a dry, slightly brownish yellow colonies. It has been isolated from soil. It is an infrequent opportunistic human pathogen, primarily in patients that are immunocompromised or have implantable subcutaneous central venous catheters.

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Hydrogenophaga flava (Pseudomonas flava)

An aerobic, oxidase-positive, gram-negative bacillus that produces a pale yellow to yellow colony. It has been isolated from soil. There have not been any reports of human infections.

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Janthinobacterium lividum

An aerobic, oxidase-positive, gram-negative bacillus that produces a violet pigmented colony. It is common is the soil and water in temperate regions. There have not been any reports of human infections.

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Kingella kingae

An aerobic, oxidase-positive, gram-negative bacillus or coccobacillus that grows readily on most general purpose microbiological media. It is part of the normal respiratory flora of humans. Rarely, it is an opportunistic pathogen for humans.

Klebsiella species

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a white colony that has either a smooth or mucoid consistency. They are part of the normal intestinal flora of humans and animals and have been isolated from plants, soil, water and sewage. They are important causes of nosocomial (hospital-acquired) and community-acquired infections in humans.

Klebsiella oxytoca

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a white colony with either a smooth or a mucoid consistency. It is similar to Klebsiella pneumoniae except that the indole test is positive. It is part of the normal intestinal flora of humans and animals. It can be isolated from soil, plants, water, and sewage. It is capable of causing infections in humans.

Klebsiella ozaenae

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth colony. It may be part of the normal intestinal flora of humans and animals It is capable of causing chronic nasal mucosa infections in humans.

Klebsiella planticola

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth, white colony. It is capable of growing at 10oC. It can be isolated from plants, seeds, leaves, redwood chips, pulp and paper mill effluent, drinking water, and soil. It is rarely isolated from human and animal clinical specimens. There have been no reports of it causing human or animal infections.

Klebsiella pneumoniae

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a white colony with either a smooth or a mucoid consistency. It is part of the normal intestinal flora of humans and animals. It can be isolated from grain, dairy products, soil, water and sewage. It is an important cause of nosocomial (hospital-acquired) infections and community-acquired infections in humans.

Klebsiella terrigena

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth, white colony. It is capable of growing at 10oC. It can be isolated from drinking water, surface water, sewage, and soil. There have been no reports of it causing human and animal infections, or occurring in clinical specimens.

Kluyvera cryocrescens

An aerobic gram-negative bacillus that grows readily on most microbiological media producing a smooth colony. It may be isolated from clinical specimens, however, it is more commonly isolated from the environment including soil, water, sewage, and the hospital environment. It is capable of growth at low temperatures (5oC) as well as room temperature and normal human body temperature (35-37oC). It is an infrequent opportunistic human pathogen.

Kocuria species

An aerobic, gram-positive or gram-variable coccus occurring in pairs, tetrads (groups of four) and clusters that produces a white, yellow, pink or red colony. They are found in soil, water, and human skin. The majority of strains are nonpathogenic.

Kocuria kristinae (Micrococcus kristinae)

An aerobic, gram-positive or gram-variable coccus occurring in tetrads (groups of four) which may form large adherent clusters. It produces pale cream to pale orange colonies. The primary habitat is mammalian skin. The majority of strains are nonpathogenic, but some strains may be opportunist pathogens.

Kocuria rosea (Micrococcus roseus)

An aerobic, gram-positive or gram-variable coccus occurring in pairs, tetrads (groups of four) and clusters that produces a pink or red colony. They are found in soil, water, and rarely on human skin. The majority of strains are nonpathogenic.

Kocuria varians (Micrococcus varians)

An aerobic, gram-positive or gram-variable coccus occurring in tetrads (groups of four) and irregular clusters of tetrads or rarely in packet or as single cells. It produces a yellow colony. They are found on mamalian skin, beach sand, and water. The majority of strains are nonpathogenic.

Kurthia zopfii

A large aerobic gram-positive bacillus that produces large creamy or yellow colonies. It can be isolated from meat and meat products, air, soil, animal dung, water, and milk. Rarely, it is an opportunistic pathogen for humans.

Kytococcus sedentarius (Micrococcus sedentarius)

An aerobic, gram-positive or gram-variable coccus occurring in tetrads (groups of four) or in tetrads in cubical packets. It produces a cream white or deep buttercup yellow colony. It is found primarily on mammalian skin. The majority of strains are nonpathogenic, but some strains may occasionally be opportunist human pathogens.

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Leuconostoc paramesenteroides

An aerobic, gram-positive coccus occurring in pairs and chains producing grayish-white colonies. It can be isolated from plants, occasionally from milk and milk products, the female genital tract, and the human gastrointestinal tract. Infectious for humans that have had surgery, antibiotic therapy, or have impaired immunological systems.

Listeria grayi

An aerobic, gram-positive bacillus producing small, nonhemolytic, cream colored colonies, later becoming reddish-orange. It can be isolated from the feces of chinchillas, hamsters, and other rodents. They are not pathogenic for humans or animals.

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Methylobacterium species

An aerobic, gram-negative bacillus producing small, pink to red pigmented colonies that grow poorly on most media. It can be isolated from air, soil, water, sewage, rumen of cows, plants (especially perennial ryegrass, tobacco, soybean) and from the hospital environment. It is capable of causing infections in immunologically compromised patients (bone marrow transplant patients, patients on dialysis, patients with catheters, and patients with cancer).

Microbacterium species

An aerobic, gram-positive bacillus that produces a yellow pigmented colony. It is rarely isolated from the environment. There have not been any reports of human infections.

Microbacterium species (CDC Group A - 4)

An aerobic, gram-positive bacillus that produces a yellow pigmented colony. It is rarely isolated from the environment. There have not been any reports of human infections.

Microbacterium species (CDC Group A - 5)

An aerobic, gram-positive bacillus that produces a yellow pigmented colony. It has been isolated from soil and from clinical specimens. Rarely, it can be an opportunistic pathogen for humans.

Microbacterium arborescens

An aerobic, gram-positive bacillus that produces a yellow pigmented colony. It is rarely isolated from the environment. There have not been any reports of human infections.

Micrococcus species

Micrococci are aerobic, gram-positive or gram-variable cocci that are arranged singly, in pairs, tetrads (groups of four) or clusters.