EMSL Analytical Lab, Inc.
This is a gram-negative rod common in activated sludge and fresh water
ditches. It is not considered clinically significant.
These gram-negative rods occur naturally in soil, water, and sewage.
These gram-negative rods are parasitic or commensal in humans, many
mammals, and birds.
These slender gram-positive rods occur mainly in the oral cavity and on
mucous membranes of warm-blooded vertebrates. They commonly cause
infections in association with other bacteria.
These gram-negative rods occur in fresh water and sewage. Some species are
pathogenic to frogs, fish, and humans (e.g. A. hydrophila for
humans, which can cause gastrointestinal (GI) infections).
These gram-negative rods occur in water, soil and the intestinal tracts of
vertebrates. They occasionally cause opportunistic infections in humans.
This gram-negative rod usually occurs in stagnant freshwater environments.
These gram-positive rods are widely distributed in the environment,
principally in soils.
These gram-positive rods are found in soil and dairy products, but are
probably widely distributed in the environment.
Bacillus is a gram-positive rod that is found in a wide range of habitats.
A few species are pathogenic to animals and humans (e.g. B. anthracis,
and B.cereus, B. thuringiensis, which can cause GI
This is a zoonotic pathogen indigenous to dogs and cats.
These gram-positive rods are found in the mouth and intestinal tract of
warm-blooded vertebrates, in insects, and in sewage. They are usually
These gram-positive rods are widely distributed in dairy products and are
found on human skin.
(Originally named Pseudomonas)
These environmental organisms are found in water, soil, and on plants,
including fruits and vegetables. They are rarely associated with human
is a Gram negative rod that can be found in the reproductive organs,
intestinal tract and oral cavity of humans and animals. Some species are
pathogenic for humans.
These gram-negative rods occur in the nasal flora of humans. They can be
pathogenic to humans.
These gram-positive rods are widely distributed in soils and decaying
This gram-negative bacterium was first classified as Cellulomonas. It was
originally isolated from the hindgut contents of the Australian
termite Mastotermes darwiniensis (Froggatt). It has also been
isolated from humus soils
These gram-negative rods are soil and water organisms. One species
occasionally causes infections in mammals, including humans.
These gram-negative rods are not normally found in the environment but in
warm-blooded animals, where they may be occasionally pathogenic.
These gram-positive rods are obligate parasites of flowering plants, in
which they are pathogenic.
This is a gram-negative rod commonly found in the environment. It
constitutes a significant proportion of many terrestrial and
aquatic environmental microbial communities
These gram-positive rods are primarily obligate parasites of mucous
membranes or skin of mammals, but occasionally they are found in other
sources. Some species are pathogenic for mammals (e.g. C. diphtheriae,
which can cause diphtheria, and C. jeikeium, which can cause
urinary tract infections)
These gram-positive rods occur on plants, in soil, and in oil brine. One
species is a plant pathogen.
This gram-positive coccus is probably widely distributed in the
Escherichia coli (E. coli)
are Gram negative rods that occur as normal flora in the lower part of the
intestine of warm-blooded animals. E. coli strains that contain
enterotoxins and/or other virulence factors including invasiveness and
colonization factors cause diarrheal disease. E. coli is also a major
cause of urinary tract infections and nosocomial infections including
septicemia and meningitis.
These gram-negative rods are widely distributed in nature, occurring in
fresh water, soil, sewage, plants, vegetables, and animal and human feces.
Several species are opportunistic pathogens.
This gram-positive coccus occurs widely in the environment, particularly
in the feces of vertebrates. Sometimes this organism can cause infections
(e.g. E.faecalis and E. faecium, which can cause urinary
tract infections and septicaemia).
Members of this genus (gram-negative rods) are a diverse group of
organisms that primarily colonize plants, and have rarely been isolated
from humans. Some of them are important pathogens of potato and other
This is a gram-positive rod found in the environment, which is not
considered clinically significant.
This gram-negative rod is found in the general environment, and in
warm-blooded animals, where it may be occasionally pathogenic.
These gram-negative rods are widely distributed in soil and water. They
are also found in raw meat, milk and other food, in the hospital
environment, and in human clinical material.
These gram-positive or gram-variable rods are isolated from soil and some
This is a gram-negative rod found in the environment, specifically in
activated sludge and lake snow.
This is a gram-negative rod, occurring in soil and water, common in
temperate climates. It occasionally causes food spoilage.
These gram-negative rods occur in human feces and clinical specimens,
soil, water, grain, fruits, and vegetables. Some species are opportunistic
These gram-negative rods occur in food, soil, sewage, and human clinical
specimens. They are infrequently opportunistic pathogens.
These gram-positive rods are widely distributed in the environment, and
are common in animal feces and meat products.
long Gram positive rods are widely distributed in the environment,
especially in animal and vegetable food products. They normally inhabit
the gastrointestinal tract of birds and mammals and the mammalian vagina.
They are rarely pathogenic but are considered to be spoilage organisms in
the food industry.
This fastidious gram-negative rod is isolated from surface water, mud, and
thermally polluted lakes and streams. There is no known soil or animal
source. It is pathogenic for humans, causing pneumonia (Legionnaires’
disease) or a mild, febrile disease (Pontiac fever).
This gram-positive rod is widely distributed in the environment. Some
species are pathogenic for humans and animals (e.g. L. monocytogenes).
These are mostly isolated from water and leaf surface microflora, and are
facultative methylotrophs, that is capable of growing on one-carbon
compounds such as formate, formaldehyde, and methanol as the sole source
of carbon and energy, as well as on a wide range of multicarbon
This gram-positive rod is found in dairy products, sewage, and insects.
These gram-positive cocci occur primarily on mammalian skin and in soil,
but are commonly isolated from food products and the air.
This gram-negative rod is parasitic on the mucous membranes of humans and
other warm-blooded animals.
rod is not readily stained by Gram’s method, usually weakly Gram positive,
grows very slowly. Widely distributed in soil and water, some species are
obligate parasites and pathogens of vertebrates.
These gram negative rods were originally included with Sphingomonas
gram-negative rods are isolated from plant surfaces, seeds, soil, and
water, as well as from animals and human clinical specimens. They are
opportunistic human pathogens.
gram-negative rods are isolated from human clinical specimens and from
gram-negative rod is widely distributed in nature. Some species are
pathogenic for humans, animals, or plants (e.g. P. aeruginosa).
gram-negative rod is associated with fish, processed meat and poultry
products. Some strains have been isolated from pathological specimens from
humans and animals.
gram-negative rods occur in freshwater. They are occasionally isolated
from human clinical specimens, but are not considered clinically
these species are phytopathogens of terrestial plants. Their main habitats
are their respective plant hosts.
organisms are aerobic, Gram positive actinomycetes. These widely-occurring
organisms are of considerable environmental and biotechnological
importance due to their broad metabolic diversity and array of unique
enzymatic capabilities, plus their capacity to degrade hydro-carbons. They
are able to survive for a long time in soil. They are the most efficient
in oil degradation and, relatively speaking, the most abundant in soils
and marine environments.
the common name given to a group of small, rod-shaped, gram negative
bacteria, which are able to produce nodules on the roots, or on some cases
the stems, of leguminous plants.
Gram negative rods occur in humans, warm and cold blooded animals, foods
and the environment. They are pathogenic for humans and many animal
species. They are the causative agents of typhoid fever, enteric fevers,
gastroenteritis and septicemia.
gram-negative rods occur in human clinical specimens, soil, water, plant
surfaces, and other environmental sites, digestive tracts of rodents, and
insects. Some species are opportunistic pathogens.
Gram negative rods are intestinal pathogens of humans and other primates,
causing bacillary dysentery.
This is a
gram-negative rod found in soil, on plants, foodstuffs, and in water
gram negative rods were originally included with Sphingomonas (see
This is a
relatively new genus derived from Pseudomonas paucimobilis. These
organisms are widely distributed, including having been found in water.
Only Sphingomonas paucimobilis is considered clinically
significant, and has been isolated from a variety of clinical specimens.
gram-positive coccus is mainly associated with the skin and mucous
membranes of warm-blooded vertebrates, but they are often isolated from
food products, dust and water. Some species are opportunistic pathogens of
humans and animals, or produce extracellular toxins.
Gram positive cocci are parasites of vertebrates, mainly inhabiting the
mouth and upper respiratory tract. Some species are pathogenic for humans
gram-positive rods are isolated from soil, human sputum, and parts of bed
bugs. Some strains can be pathogenic.
gram-negative rod is not known in the general environment. It is
apparently a parasite, saprophyte, or commensal of the internal surfaces
of humans or other warm-blooded animals.
gram-negative rods occur in a broad spectrum of habitats, including
humans, animals, soil, water, dairy products, and other foods. Some
species are pathogenic for humans and animals; others are opportunistic
pathogens, yet others are nonpathogenic.
these gram-negative rods are plant pathogens, or occur in association with
plants. X.maltophilia is the only exception, being an opportunistic
pathogen of humans.
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GLOSSARY OF TERMS
Commensal – organisms existing in or on an animal or human without
Extracellular – produced, then excreted outside the organism.
Gram-positive – bacteria that stain purple (positive) with the gram
Gram-negative – bacteria that do not stain purple (pink – negative)
with the gram stain.
Habitat – where an organism is found.
Indigenous – where normally found
Opportunistic – an organism that will only cause disease in a patient
with a poor or somehow weakened immune system.
Pathogens – organisms that cause disease.
Saprophyte – an organism that normally grows on dead material.
– compounds produced by an organism that are poisonous to other organisms
Zoonotic – organism normally found in or on animals.
are naturally present in the environment and on and in humans and animals.
They have many good uses:
line the gut, where they aid digestion.
remove debris on the skin.
are important in many foodstuffs, such as cheeses and yogurts.
aid in the maturation of meat.
remove trash in the environment.
"normal" environmental system will have an assortment of different
bacterial types, none of which will be particularly predominant. In areas
where there are high numbers of humans, there may be higher levels of
gram-positive cocci, such as Staphylococcus and Micrococcus,
in the environment. Unlike molds, higher numbers of bacteria in the
air inside can be normal.
levels of one type of bacteria, especially gram-negative rods, notably
those in the Enterobacteriaceae, are considered significant:
Enterobacteriaceae are indicative of sewage contamination, and therefore
of pathogenic organisms. Pathogenic bacteria themselves are rarely
recovered, as they are rapidly outgrown by environmental bacteria, hence
the development of the sewage screen to detect potential
one organism has removed the natural competition, it implies more than
just simple co-existence of several different types, but suggests a more
aggressive role by the dominant organism.