Major Bacterial Genera

Coagulase Test

detects presence of catalase enzyme, which breaks down hydrogen peroxide to water and oxygen

Coagulase test

detects presence of coagulase enzyme which binds fibrinogen to form fibrin

Oxidase test

detects presence of cytochrome oxidase system

B- hemolysis

complete clearing of the red blood cells around the bacterial colony

alpha- hemolysis

partial lysis of the cells resulting in a greenish-discoloration around the colony

gamma- hemolysis

bacteria have no effect on the red blood cell

Gram-positive cocci

Staphylococcus, Streptococcus, Enterococcus

Gram-positive rods

Bacillus, Listeria, Corynebacterium, Nocardia

Gram-negative cocci

Neisseria, Acinetobacter, Moraxella

Gram-negative rods

Escherichia, Klebsiella, Serratia, Enterobacter, Proteus, Salmonella, Shigella, Yersinia, Pseudomonas, Haemophilus, Bordatella, Legionella, Pasturella, Francisella, Brucella, and Bartonella

Enterobactericeae

Escherichia, Klebsiella, Serratia, Enterobacter, Proteus, Salmonella, Shigella, Yersinia

Opportunist

Pseudomonas

Pathogens of human respiratory tract

Haemophilus, Bordetella, Legionella

Primarily Pathogens of animals

Pasturella,, Francisella, Brucella

Gram-positive anaerobes

Actinomyces, Clostridium

Gram-negative anaerobes

Bacteroides, Prevotella, Porphyromonas

Curved Bacteria

Vibrio, Campylobacter

Spiral Shaped Bacteria

Helicobacter

Spirochetes

Borrelia, Treponema

Obligate Intracellular Bacteria

Chlamydia, Chlamydophila, Rickettsia, Ehrlichia, Anaplasma, Coxiella

Staphylococcus

Gram-positive, cocci, grape-like clusters, facultative anaerobe, catalase-positive, Salt tolerant, Coagualse positive (S. aureus) and Coagulase negative (most are considered normal flora)

S. aureus

Coagulase- positive
B-hemolytic
major human pathogen

Streptococcus

Gram-positive cocci
pairs or chains
Facultative anaerobes
catalase-negative
lancefield antibodies to cell wall carbs are used to classify
some are pathogenic while others are part of normal flora

Enterococcus

gram-positive cocci in chains
catalase negative
lancefield group D antigen-positive
tolerant to NaCl and to bile salts
part of normal gastrointestinal flora
frequent nosocomial infections
antibiotic resistance

Bacillus

Large, gram positive spore forming rods in chains
aerobic
members of this genus cause anthrax and food poisoning
most have little to no pathogenic potential

Listeria

short, gram-positive non spore forming rods
will grow at lower temperature
facultative aerobes
facultative intracellular
displays tumbling
l. monocytogenes is the only pathogen

Cornyebacterium

Gram-positive
club-shaped
non-spore forming rods
aerobic
C. diptheriae is the causative agent of diptheria

Nocardia

Gram-positive
filamentous branching
aeorbic, slow growing
weakly acid fast
found in soil and water
infection in immunocompromised

Neisseria

Gram-negative
cocci in pairs (kissing kidney beans)
typically found in PMN cells (facultative intracellular)
aerobic, grows best on chocolate agar in atmosphere containing CO2
Ferments glucose
oxidase positive
both pathogenic and non-pathogenic colonize mucosal surfaces

N. gonorrhea

ferments glucose only
causes genital infections and eyesight-threatening conjuctivitis

N. meningitides

ferments glucose and maltose
causes meningitis

Acinetobacter

Cocco-bacillary
strictly aerobic
does not ferment carbohydrates
oxidase negative, non motile
widely distributed in soil and water
frequently resistant to antibiotics
important nosocomial pathogens

Moraxella

small gram-negative coccobacilli
strictly aerobic
oxidase-positive, non-motile
do not ferment carbs
normal upper respiratory flora
cause otitis media, bacterimia, meningitis, and other infections

Enterobactericiae

Large, non spore forming gram-negative rods
ferment glucose
oxidase negative
facultative anaerobes or aerobes
GI tract of human and animals
complex antigenic structure
produce endotoxins

Escherichia

Enterobactericeae
Ferment lactose
motile
causes UTI, gastroenteritis, cystitis, pyelonephritis, appendicitis, peritonitis, gall bladder infections, septicemia, neonatal meningitis, pneumonia, endocarditis

Klebsiella

Entrobactericeae
Ferments lactose
non-motile
mucoid colonies due to polysaccharide capsule
can cause pneumonia, UTI or GI tract infection, many infections are hospital acquired

Serratia

Enterobactericeae
ferment lactose
DNAse positive
some stains produce a characteristic red pigment
important nosocomial pathogen

Enterobacter

Enterobactericeae
ferments lactose
motile
opportunistic pathogens

Proteus

Highly motile, display swarming motility
Do not ferment lactose
produce urease and H2S
common cause of UTI, urease produced by Proteus spp. lowers the pH of urine causing formation of stones

Salmonella

Do not ferment Lactose
produce H2S
motile
many serotypes
transmitted from animals and animal products via the oral route
can cause enteritis, systemic infection and enteric fever

Shigella

Does not ferment lactose
non-motile
natural habitat is limited to GI of humans
Causes bacillary dysentery, infections almost always limited to GI tract

Yersinia

Enterobacteria
short pleomorphic gram-negative rod
exhibits bipolar staining
does not ferment lactose
motile except for Y. pestis
animals and rodents are important reservoirs for Yersinia spp.
Y. pestis is the causative agent of plague
Y. enerocolitica and Y. psetudotuberculosis are important causes of diarrheal diseases

Pseudomonas

Important opportunist
do not ferment glucose
oxidase positive
motile by means of polar flagella
occurs widely soil, water, plants and animals
frequently a nosocomial pathogen
can colonize human sand cause infections in hosts w/ compromised defenses
resistant to many antimicrobials
causes infections in wounds and burns, meningitis, UTI, respiratory infections, sepsis and other infections

Haemophilus

Small, gram-negative, pleomorphic bacilli
fastidious media containing factor X and factor V for growth (chocolate agar)
part of normal flora of upper resp. tract and mouth
H. influenzae was an important cause of meningitis in children
pathogenic haemophilus spp. can also cause endocarditis, conjuctivitis, and chancroid

Bordetella

small, gram-negative coccobacilli that grow singly or in pairs
fastidious
requires special media containing blood and charcoal to absorbents and/or neutralize to remove inhibitory substances
highly communicable, transmitted person to person
causes whooping cough
vaccine available

Legionella

Gram-negative rods that stain poorly by gram stain
fastidious and slow growing
requires BCYE and grow w/i 3-5 days
facultative intracellular organism
temp ranges 4-55 C
ubiwuitous in warm, moist environments
transmission via inhalation
causes legionnaire's disease

Pasturella

small coccobacillus
do not ferment glucose
oxidase positive
normal flora in wild and domestic animals
causes cellulitis or abscess subsequent to a cat or dog bite or scratch

Francisella

Small gram negative pleomorphic rods
fastidious, requires cysteine
highly infectious, inhalation
facultative intracellular organisms
can be transmitted by consumption of contaminated food or water by inhalation of aerosols through bitting arthropods or by contact w/ infected animal tissue
causes tularemia

Brucella

facultative intracellular organism, obligate parasites of animals and humans
gram negative coccobacillary rods
fastidious required enriched media and require extended time to grow
transmission occurs via contact w/ animals
cause brucellosis

Bartonella

Pleomorphic gram negative rods
slow growing and difficult to isolate in lab
can be detected in tissues using a warthin-starry silver impregnation stain
falcultative intracellular organism
cause oroya fever and verruga peruana, trench fever, cat scratch disease

Actinomyces

Gram-positive branching rods
facultative anaerobe that prefers anaerobic conditions
non-acid fast
soil organisms
normal flora of gingival crevices and female genital tract
disease arises from tissue damage that allows the organism to penetrate

Clostridium

Large, gram-positive spore-forming rods
anaerobic
saprophytic organisms found in the soil or intestinal tract of humans and animals
pathogenic members of the species cause tetanus, gas gangrene and food poisoning

Bacteroides

can appear as slender rods or coccobacilli
gram-negative anaerobes
normal inhabitants of human colon
cause disease when they gain access to tissues or blood during bowel penetration
major player in infection is B. fragilis
drug resistance is common

Prevotelle, Porphyromonas

pigmeneted gram-negative anaerobes
normal flora that can cause infection

Vibrio

curved gram-negative rods
motile, via a polar flagellum
some require salt to grow
oxidase-positive
widely distributed in nature, most common bacteria in surface waters
cause GI infections, including cholera

Campylobacter

curved, gram-negative rods (gull-wing shape)
motile, via polar flagellum
requires an atmosphere w/ reduced O2 and CO2
cultures should be incubated at 42C to prevent growth of other bacteria present in feces
oxidase positive
infection is acquired orally via consumption of food or water or contact w/ infected animals
common cause of diarrhea in humans

Helicobacter

gram-negative spiral shaped bacteria
motile, multiple flagella at one pole
strong producer of urease
H. pylori is known to cause peptic ulcer disease

Spirchetes (general characteristic)

gram-negative flexible, helical shaped bacteria
helically shaped protoplasmic cylinder
multilayered outer membrane surrounding protoplasmic cylinder
periplasmic flagella positioned in periplasmic space (endoflagellum)
not reliably detected by gram stain, can be visualized using dark-field microscopy or fluorescent antibody staining

Treponema

has never been cultured
lab diagnosis relies on microscopy or serology
T. pallidum is the causative agent of syphilis

Borrelia

arthropod-transmitted spirochetes
B. burdorferi cause lyme disease other Borrelia spp. are the causative agents for tick borne or endemic relapsing fevers

Chlamydia and Chlamydophila

gram-negative bacteria
have an inner and rigid outer membrane that lacks peptidogylcan
lack mechanisms for production of ATP and NAD
Organism has an elementary body and a reticulate body
Diagnosis through serology, culture, florescent antibody staining and/or gene probes
can cause pneumonia, sexually transmitted diseases and eye infections

Elementary bodies

environmentally stable infectious particles that are metabolically inert and can attach to host cells

Reticulate bodies

metabolically active forms of the organism they undergo binary fission to produce more elementary bodies

Rickettsia

Obligate intracellular pathogens that are arthropod borne
multiply in endothelial cells of small blood vessels and produce capillary leakage and vasculitis
escape into cytosol, multiply and spread into other endothelial cells
cause rocky mountain spotted fever, scrub typhus and other disease

Ehrlichia and Anaplasm

infect leukocytes and multiply w/i phagocytic vaculoles orgaisms divide to form membrane-bound colonies called morulae

Anaplasma phagocytophilum

causes human granulocytic ehrlichiosis and is transmitted by contact w/ ixodes ticks

Ehrlichia chaffeensis

causes human monocyte ehrlichiosis and is transmitted by contact w/ the lone star tick

Coxiella

zoonosis that is widespread in animals found in cattle, sheep, goats, and cats among others, found in placenta, mammary glands and mild
killed by pasteurization but is resistant to drying and can survive for months in dried feces of milk
causative agent of Q fever

Mycoplasma

smallest extracellular bacteria
fried egg appearance
lack a cell wall, but have a triple layered unit membrane that contains sterols, require sterols for growth
highly pleomorphic
extremely sensitive to environmental conditions
extremely fastidious
normal inhabitants of human mucous membranes, particularly the genital, urinary, and respiratory tracts exception m. pneumoniae
can cause pneumonia as well as genitourinary infections
completely resistant to b-lactam antibiotics

Mycobacteria

small, straight rods, stain poorly
waxy cell envelope
cell wall contains mycolic acids
acid fast bacteria
resistant to chemical agents to drying and to germicides
oblicate aerobes that are very slow growing w/ a doubling time over 18 hours
some members infect healthy individuals, and others are opportunistic pathogens
pathogenic members of the genera include M. tuberculosis, M. avium-intracellulare, M. leprae and others