Microbiology Flashcards
G(+) cocci arranged in clusters
colonies are opaque and smooth
grows well on most media
beta-hemolytic on sheep blood agar (SBA)
catalase (+)
coagulase (+)
(-) ability to metabolize pyrrolidonyl-alpha-naphthylamide (PYR) and ornithine
can tolerate high salt concentration of mannitol salt agar
penicillin-resistance
Staphylococcus aureus
G(+) cocci arranged in clusters
colonies appear white to gray on blood agar
nonhemolytic
catalase (+)
coagulase (-)
most common coagulase (-)
novobiocin (S)
Staphylococcus epidermidis
G(+) cocci arranged in clusters
colonies appear white to gray on blood agar
nonhemolytic
catalase (+)
coagulase (-)
novobiocin (R)
significant only in UTIs
Staphylococcus saprophyticus
G(+) cocci arranged in clusters
colonies appear white to gray on blood agar
nonhemolytic
catalase (+)
coagulase (-)
PYR (+)
ferments manitol
clumps in plasma
frequent cause of endocarditis
Staphylococcus lugdunensis
normal flora of the skin and mucous membranes
GS: arranged in tetrads, larger than Staphylococcus spp
appear yellow and non hemolytic on SBA
acid production from glucose under anaerobic conditions (-)
modified oxidase test (+)
bacitracin (S)
Micrococci spp
catalase (-)
G(+) cocci arranged in pairs and chains
alpha or beta hemolytic or non hemolytic on SBA
Lancefield grouping is based on a cell wall antigen
Streptococcaceae
Infections spread by respiratory secretions
cause pharyngitis, impetigo, cellulitis, scarlet fever, otitis media, nectrotizing fasciitis
sequelae include rheumatic fever, post streptococcal glomerulonephritis
bacitracin (S)
PYR positive
colonies pinpoint, translucent, beta hemolysis
group A stretococcus
pathogenic group A streptococcus
S. pyogenes
group A strep virulence factors: inhibits phagocytosis and antibodies formed against this are protective
cell wall M protein
group A strep virulence factors: causes rash seen in scarlet fever; acts as superantigens interacting with macrophages and associated with streptococcal toxic shock syndrome (STSS)
exotoxin (Spe A, B, C, F)
group A strep virulence factors: dissolves clots
streptokinase
group A strep virulence factors: inhibits phagocytosis
hyaluronic acid capsule
group A strep virulence factors: lyse erythrocytes, platelets, neutrophils
streptolysin O & S
group A strep virulence factors: hydrolyzes hyaluronic acid, an interstitial barrier, facilitating spread of the infection
hyaluronidase
isolates typically express Lancefield group C or G antigens
clinical spectrum of disease resembles S. pyogenes and include pharyngitis, skin infections, necrotizing fasciitis, STSS, endocarditis, glumerulonephritis, acute rheumatic fever
S. dysagalactiae subspecies equisimilis
normal flora of GI tranct
cause infection in OB/GYN patients
neonates acquire infections during birth, resulting in sepsis and meningitis
can cause endocarditis, pneumonia, pyelonephritis in immunocompromised patients
colonies are medium-sized (>1mm), flat, creamy and show small zones of beta hemolysis
CAMP test (+)
hippurate hydrolysis (+)
PYR (-)
bacitracin (R)
group B streptococcus
normal fecal and oral flora
associated with wound infections, UTIs and abdominal abscesses
isolation in blood cultures is an indicator of colon cancer
colonies are gray to white, translucent, round and convex
alpha hemolytic or nonhemolytic, rarely beta
bile esculin (+)
6.5% NaCl (-)
PYR (-)
group D non-enterococcus
normal flora of the oral cavity, respiratory tract and GI tract mucosa
major cause of bacterial endocarditis; also causes wound infections and brain abscesses
may enter the blood after dental procedures
alpha hemolytic, some strains non hemolytic
optochin (R)
bile (insoluble)
does not grow on bile-esculin medium
viridans streptococci
normal upper respiratory tract flora but can cause lobar pneumonia, otitis media, meningitis
G (+) diplococci that are lancet or bullet-shaped and alpha hemolytic
grows on SBA with 5-10% CO2 at 48h
mucoid strains produce a large polysaccharide capsules
umbilicated, depressed centers caused by autolytic enzymes
s. pneumoniae
rust-colored sputum and lobar pneumonia is often associated with ____
s. pneumoniae
most common encountered sp of enterococcus
e. faecalis
e. faecium
bile esculin (+)
6.5% NaCl (+)
PYR (+)
lancefield group D antigen
alpha-, beta-, non-hemolytic
enterococcus
associated with a number of infections including endocarditis, meningitis, lung abscesses and osteomyelitis
PYR (+)
leucine aminopeptidase (+)
bile esculin (-)
gemella
have been linked osteomyelitis, ventriculitis, postsurgical endophthalmitis, and bacteremia in neonates
vancomycin (R)
PYR (-)
LAP (-)
catalase (-)
leuconostoc
require vitamin B6 for growth
normal flora of the oral cavity and have associated with endocarditis, ophthalmic infections, infections of the CNS
abiotropha
granulicatella
causes spontaneous abortion and meningitis in animals
found in environment, normal flora of the vagina and intestines in human
grows on most media
colonies are white and small with a narrow zone of beta hemolysis
closely resemble group B strep on SBA
umbrella motility in semi-solid media and end-over-end tumbling in a wet mount
hippurate hydrolysis (+)
CAMP (+)
esculin (+)
catalase
listeria monocytogenes
pseudomembrane formed by dead cells and exudates at the back of the throat
found only in humans
gram stain: picket fence or chinese letters
methylene blue: metachromatic granules
urease (-)
pyrazidamidase (-)
nitrate (+)
catalse (+)
non-motile
corynebacterium diphtheria
what test uses antitoxin to detect toxin production of the C. diphtheria
elek test
appearance of corynebacterium spp: cystine-tellurite
black colonies
appearance of corynebacterium spp: tinsdale’s agar
brown to black colonies with halos
appearance of corynebacterium spp: loeffler agar
small white to gray colonies
appearance of corynebacterium spp: SBA
small, white, dry colonies
non hemolytic
important cause of nosocomial infections and produces infections after prosthetic implants and infections in immunocompromised patients
pyrazidamidase (+)
antimicrobial agents (R)
corynebacterium jeikeium
cause UTIs
rapid urease (+)
grows very slowly
corynebacterium urealyticum
6 species but 3 clinically significant
natural habitat have not been confirmed
small beta hemolytic colonies on SBA
catalase (-)
non motile
arcanobacterium
associated with pharyngitis and wound and tissue infections
small beta hemolytic colonies on SBA
catalase (-)
non motile
can be identified with CAMP inhibition test
arcanobacterium haemolyticum
found on mucous membranes of cattle, sheep, and swine
linked to abscess formation, wound and soft tissue infections in cattle and humans
small beta hemolytic colonies on SBA
catalase (-)
non motile
arcanobacterium pyogenes
produced by a. haemolytitcum
inhibits the activity of staphylococcus aureus beta-lysin
this phenomenon is also exhibited by ___
phospholipase D
c. pseudotuberculosis
primarily infects animals
human generally become infected through contact with infected animals or by consuming infected meat
causes cellulitis, bacteremia or endocarditis
non motile
pleomorphic G(+) bacilli
catalase (-)
H2S (+)
erysipelothrix rhusiopathiae
erysipeloid lesions that resembles erysipelas caused Streptococcus pyogenes
cellulitis
generally found in immunocompromised patients with chronic pulmonary disorders
most clinically relevant species
pleomorphic, branching G (+) bacilli in chains that produce a beading arrangement, appear fungal-like
partially acid fast
catalase (+)
non motile
requires up to 6w for growth
exudates contain masses of filamentous organism with pus that resemble sulfur granules
nocardia asteroides
bacterial spores contain ____ which makes them resistant to adverse environment
calcium dipicolinate
can survive adverse conditions for prolonged periods of time and are frequent contaminants of laboratory cultures
can be centrally or terminally located
bacterial spores
form straight bacilli with square ends (box-car morphology) appearing in chains and singly
SBA (+)
phenylethyl alcohol (PEA) agar (+)
catalase (+)
large, flat colonies
bacillus spp
causes anthrax
potential bioterrorism agent
large non hemolytic agent with filamentous projections (Medusa head) colonies
PEA (-) at 24 hr
preliminary testing by sentinel lab: typical colony morphology, G(+) bacilli with spores, catalase (+) non motile
bacillus anthracis
3 clinical forms of anthrax
cutaneous anthrax
pulmonary anthrax
gastrointestinal anthrax
most common form of anthrax
cutaneous anthrax
skin lesions of cutaneous anthrax
black eschar
pulmonary anthrax
spread by inhalation of spores from sheep’s wool
wool-sorter’s disease
important cause of food poisoning and occasionally wounds, may also cause opportunistic eye, bone and brain infections
large, flat, beta hemolytic colonies with irregular edges
motile
penicillin (R)
bacillus cereus
oxidase (+)
fastidious and grow best in 5-10% CO2 at 37degC
cannot tolerate cold
neisseriaceae
neisseriaceae includes these genera
neisseria
eikenella
kingella
simmonsiella
not a normal flora
humans are their only host
fastidious
doses not survive long outside the host
be isolated from the urethra, cervix, anal canal, oropharynx, skin lesions, joins and blood
neisseria gonorrhoeae
gonorrhea in males
characterized by pus-containing urethral discharge and dysuria
acute urethritis
gonorrhea in females
UTI
cervicitis (cervical discharge, fever, acute pain, dysuria)
pelvic inflammatory disease
gonococcal arthritis
salphingitis
endometritis
peritonitis
to prevent newborn conjunctivitis, this is being administered to all infants at birth
erythromycin
Gram stain: appears intracellular to neutrophils
fastidious, requiring enriched media such as chocolate agar plate, Thayer Martin, Martin-Lewis, New York city and GC Lec Agars
SBA (-)
require increased CO2 with humidified atmosphere
autolysis, cannot be incubated for prolonged times
flat, smooth and glistening gray or tan colonies
superoxol (+)
catalase (+)
oxidase (+)
glucose (+)
maltose (-)
lactose (-)
sucrose (-)
DNAse (-)
nitrate (-)
beta lactamase (+) most
neisseria gonorrhoeae
spread by respiratory droplets and may be normal flora of the nasopharynx
causes meningococcal meningitis, meningococcemia, leading to DIC and waterhouse-friderichsen syndrome
csf, sputum, blood and nasopharyngeal swabs
falt, smooth and gray-white colonies on chocolate agar
SBA with increased CO2: bluish-gray colonies
catalase (+)
oxidase (+)
glucose (+)
maltose (+)
DNAse (-)
nitrate (-)
neisseria meningitidis
colonizes the throat of children
predilection for infections of the bones and joints in children
generally limited to those who are immunocompromised
isolated from joints and bones in blood culture media
SBA (+)
chocolate agar (+)
Thayer Martin agar (+)
MCA (-)
kingella kingae
habit unknown
most associated with endocarditis
SBA (+)
chocolate agar (+)
Thayer Martin agar (+)
MCA (-)
can reduce nitrates
kingella dentrificans
resembles neisseria
NF of the upper respiratory tract
causes otitis media, sinusitis, respiratory tract infections
grow on most nutrient agars
catalase (+)
oxidase (+)
DNAse (+)
nitrate (+)
butyrase esterase (+)
assacharolytic
carbohydrate test (-)
moraxella catarrhalis
most medically important family of G (-) bacili
normal flora of the GI tract
major cause of nosocomial infections
UTI, gastroenteritis, septicemia, food poisoning, wound infections, peritonitis, pneumonia, meningitis
facultative anaerobes
glucose (+)
nitrate (+)
catalase (+)
oxidase (-)
enterobacteriaceae
enterobacteriaceae inhibit four serological characteristics
O, K, H, Vi Ag
somatic Ag
cell wall antigen
heat stable
O Ag
envelope Ag
capsular Ag
heat labile
K Ag
flagellar Ag
heat labile
H Ag
capsular antigen of salmonella typhi
heath labile
Vi Ag
all enterobacteriaceae are oxidase negative except
plesiomonas
MAC agar:
lactose (+) ______
lactose (-) ______
pink-red
colorless
eosin-methylene blue (EMB) agar:
lactose (+) ______
lactose (-) ______
dark center
colorless
hektoen enteric (HE) agar:
lactose/sucrose (+) ______
salmonella ______
shigella ______
yellow/orange colonies
green with black centers
clear colonies
salmonella-shigella (SS) agar
lactose/sucrose (+) ______
salmonella ______
shigella ______
red colonies
colorless with black centers
colorless
bismuth sulfite agar
lactose/sucrose (+) ______
salmonella ______
shigella ______
yellow/orange colonies
black colonies
black colonies
brilliant green agar:
proteus and salmonella _____
shigella _____
lactose (+) ____
red/pink colonies
will not grow
will not grow
selenite broth:
salmonella _____
gram (+) and coliform (NF of GI) _____
enhanced
inhibited
normal GI flora
very common clinical isolate
causes UTI, appendicitis, peritonitis, gall bladder infections, endocarditis, meningitis, gastroenteritis, food poisoning
triple sugar iron (TSI): A/A, H2S (-)
MAC: pink-red colonies
SBA: shiny, opaque, off-white, 2-4 mm beta hemolytic
EMB: green metallic sheen colonies with dark centers
indole methyl red (IMB) (+)
motility (+)
o-nitrophenyl-beta-D-galactopyranoside (ONPG) (+)
voges-proskauer (VP) (-)
citrate (-)
urease (-)
escherichia coli
causes hemorrhagic colitis and hemolytic uremic syndrome leading to kidney failure in young children
eating undercooked hamburger, contaminated food eg apple cider, basil, sprouts
sorbitol-MAC agar (+)
EHEC
principal virulence factor of EHEC
shiga toxin (Stx) 1 and 2
produces severe epidemic diarrhea, mainly from drinking contaminated water
ETEC (enterotoxigenic)
causes bloody diarrhea by invading intestinal epithelium
EIEC (enteroinvasive)
causes watery diarrhea
EPEC (enteropathogenic)
highly pathogenic (less than 50 bacteria can cause disease)
direct fecal contamination from infected humans
TSI: K/A
H2S (-)
VP (-)
motility (-)
urease (-)
citrate (-)
lactose (-)
MR (+)
shigella
produces an enterotoxin, which affects the large intestines, and a neurotoxin that may result in paralysis
mannitol (-)
ONPG (-)
TSI: K/A
H2S (-)
VP (-)
motility (-)
urease (-)
citrate (-)
lactose (-)
MR (+)
S. dysenteriae
(serogroup A)
produces a mild diarrhea
mannitol (+)
ONPG (-)
TSI: K/A
H2S (-)
VP (-)
motility (-)
urease (-)
citrate (-)
lactose (-)
MR (+)
S. flexneri (serogroup B)
S. boydii (serogroup C)
produces a mild diarrhea
mannitol (+)
ONPG (+)
TSI: K/A
H2S (-)
VP (-)
motility (-)
urease (-)
citrate (-)
lactose (-)
MR (+)
S. sonnei (serogroup D)
cause UTIs and pneumonia
nosocomial, diabetics and alcoholics are prone to infections
TSI: A/A with gas
MCA: pink colonies are very mucoid
H2S (-)
MR (-)
nonmotile
indole (-)
VP (+)
citrate (+)
lactose (+)
klebsiella
most common isolated species of klebsiella
K. pneumoniae
causative agent of granuloma inguinale
does not Gram stain or grow on laboratory media
Wright’s or Giemsa stained
Donovan bodies may be seen
K. (Calymmatobacterium) granulomatis
intracellular pleomorphic bipolar staining cells
Donovan bodies
includes 12 species, found in soil, water, and dairy products
linked to respiratory tract infections and wounds, and isolated from blood
H2S (-)
MR (-)
indole (-)
VP (+)
citrate (+)
enterobacter
most common species of enterobacter
H2S (-)
MR (-)
indole (-)
VP (+)
citrate (+)
lactose (+)
arginine (+)
lysine (-)
E. cloacae
second most common species of enterobacter
H2S (-)
MR (-)
indole (-)
VP (+)
citrate (+)
lactose (+)
arginine (-)
lysine (+)
E. aerogenes
H2S (-)
MR (-)
indole (-)
VP (+)
citrate (+)
lactose (+)
produces a yellow pigment
E. sakazakii
H2S (-)
MR (-)
indole (-)
VP (+)
citrate (+)
lactose (-)
E. taylorae
causes opportunistic infection in patients undergoing chemotherapy and immunosuppressed patients
DNAse (+)
gelatinase (+)
lipase (+)
VP (+)
citrate (+)
ONPG (+)
lactose (delayed)
serratia
most common clinical isolate
DNAse (+)
gelatinase (+)
lipase (+)
VP (+)
citrate (+)
ONPG (+)
lactose (delayed)
S. marcescens
cause moderate to severe gastroenteritis
has many animal reservoirs
transmitted through contaminated water and undercooked foods especially chicken characterized by a septicemia followed by a GI tract infection
lactose (-)
H2S (+)
citrate (+)
indole (-)
urease (-)
colonies on HE agar are green with black centers
salmonella
majority of human causes of salmonellosis are due to serotypes belonging to this species
S. enterica (S. typhi)
H2S (+)
urease (+)
tryptophan deaminase (TDA) (+)
phenylalanine deaminase (+)
ONPG (-)
lactose (-)
indole (-)
Proteus mirabilis
H2S (+)
urease (+)
tryptophan deaminase (TDA) (+)
phenylalanine deaminase (+)
ONPG (-)
lactose (-)
indole (+)
P. vulgaris
phenylalanine deaminase positive
proteus
providencia
morganella
selective and differential medium for isolation of Y. enterocolitica, colonies of which will ferment mannitol and absorb the dye neutral red, producing a clear colonies with a pink center
cetsulodin-irgasan-novobiocin medium
endemic to the southwestern US
small animals (e.g. rodents) are natural reservoirs, and the bacteria are transmitted by fleas
potential bioterrorism agent
nonmotile
pinpoint colonies on SBA after 24h incubation
G (-) bacilli
oxidase (-)
urease (-)
catalase (+)
Yersinia pestis
causes enterocolitis in humans
acquired by drinking contaminated water or by eating contaminated meat
ONPG (+)
delayed lactose fermenter
sucrose (+)
colorless on MAC at 18 hours but A/A on TSI
non motile at 37 deg C but motile at 25deg C
Y. enterocolitica
rare cause of lymphadenitis in children
non motile at 37 deg C but motile at 25deg C
Y. pseudotuberculosis
resembles salmonella
H2S (+)
ONPG (-)
indole (+)
citrate (-)
Edwardsiella
most common isolate of Edwardsiella
E. tarda
most common species isolated of Citrobacter
resembles E. coli on MCA but can be differentiated because of being H2S (+)
indole (-)
C. freundii
indole (+)
VP (-)
citrate (-)
PDA (+)
TDA (+)
Morganella morganii
PDA (+)
TDA (+)
indole (+)
citrate (+)
VP (-)
most common isolate of Providencia
P. rettgeri
HACEK
fastidious (require complex nutrients for growth)
important causes of endocarditis
Haemophilus
Actinobacillus
Cardiobacterium hominis
Eikenella
Kingella
pleomorphic gram (-) coccobacilli ranging from very small to filamentous
growth requirements include X and V factor
do not grow on SBA but will grow on horse or rabbit blood agar, which contains no NADase
chocolate agar is routinely used for cultures
grows at 35-37 deg C with 5-10% CO2 and is susceptible to drying and temperature changes
colony morphology: smooth, round, flat, opaque and tan on chocolate agar
non motile
catalase (+)
oxidase (+)
haemophilus
X factor
released from hemoglobin
hemin
V factor
heat-labile compound
NAD
haemophilus spp can grow around colonies of S. aureus growing on an SBA plat since the colonies of the latter release NAD, forming a tiny clear pinpoint colonies
satellitism
x factor (+)
v factor (+)
hemolysis on horse blood agar (-)
ALA (-)
H. influenzae
H. aegyptius
x factor (+)
v factor (-)
hemolysis on horse blood agar (-)
ALA (-)
H. ducreyi
x factor (-)
v factor (-)
hemolysis on horse blood agar (-)
ALA (+)
H. aprophilus
x factor (+)
v factor (+)
hemolysis on horse blood agar (+)
ALA (-)
H. haemolyticus
x factor (-)
v factor (+)
hemolysis on horse blood agar (-)
ALA (+)
H. parainfluenzae
H. paraprophilus
has 6 capsular serotypes and 8 biotypes I-VII
should be tested for beta lactamase
can be isolated from a variety of specimens including blood, sputum, CSF, eye swabs
specific detection of Hib capsular antigen by latex agglutination
H. influenzae
major cause of meningitis in children
vaccine had greatly reduced childhood meningitis and other invasive disease caused by this serotype
H. influenzae type b
causes pink eye, a very contagious conjunctivitis
similar to H. influenzae except sucrose (+)
H. aegyptius
causes conjunctivitis followed by an invasive disease known as Brazilian purpuric fever
resembles H. influenzae biotype III in that it is indole (-), urease (+), and ornithine decarboxylase (-)
H. influenzae biogroup aegyptius
causes genital ulcers
produces chancroids and buboes (swollen lymph nodes)
chocolate agar with vancomycin is used to inhibit normal flora and contaminants
H. ducreyi
found in the water, soil, food, plants and a few are normal flora of humans
approximately 20% of all gram (-) bacilli isolates
most are obligate anaerobes
do not form spores and do not metabolize carbohydrates under anaerobic conditions
most are oxidase (+)
TSI: K/K
grow on SBA but varied growth in MCA
Non fermentative Gram (-) bacilli (NFB)
most important NFB
common clinical isolate that can infect humans, animals, plants and fish
causes eye (lens wearer) and ear infections (swimmer’s ear, external otitis)
lower respiratory tract infection in patients with cystic fibrosis
important pathogen in immunocompromised individuals
P. aeruginosa
only organism in the pseudomonas family that is capable of producing the pigment pyocyanin
only ones capable of growing both at 35 and 42 deg C
P. aeruginosa
oxidase (+)
motile
lactose (-)
large irregular colonies with grape-like odor and metallic sheen on SBA
beta hemolytic colonies with a feathery edge on SBA
mucoid colonies when isolated from patients with CF
very resistant to antimicrobial agents
P. aeruginosa
this test determines if glucose is broken down oxidatively or fermentatively
two tubes are used: one is overlayed with mineral oil to produce anaerobic conditions
the other tube contains no mineral oil (aerobic)
oxidative bacteria produce acid (yellow color) ie the open tube; whereas the closed tube is green
oxidative-fermentative glucose test
acquired as transient flora from hospitals
causes pneumonia, UTIs, wound infections
oxidase (-)
the only non fermentative, gram (-) bacillus that is oxidative (-)
maltose (+)
one of two clinically encountered NFB that is lysine decarboxylase (+)
resistant to most antimicrobials
stenotrophomonas maltophilia
causes nosocomial infections
important respiratory tract pathogen in patients with CF (second to P. aeruginosa)
enhanced growth on P. cepacia (PC) agar that inhibits P. aeruginosa
colony morphology: colorless or yellow on nutrient agar
oxidase (+)
lactose (+)
lysine decarboxylase (+)
burkholderia cepacia
causes glanders
grows on MCA
oxidative (variable)
non motile
reduces nitrate to nitrite without gas
glucose (+)
burkholderia mallei
highly contagious disease of livestock, particularly among horses, mules and donkey
can be transmitted to human by animal contact
glanders
disease of humans and animals endemic to SEA and northern Australia
has a wide range of signs and symptoms
can be mistaken for other diseases, such as tuberculosis or more common forms of pneumonia.
melioidosis
causes melioidosis
found in soil and infections are acquired through the skin or by inhalation
grows on MCA
oxidase (+)
motile
reduces nitrate to nitrite with gas
oxidizes several sugars including glucose and lactose
burkholderia pseudomallei
obligate aerobic coccobacillus found as normal flora of the GI and respiratory tracts
important cause of nosocomial infections and UTIs isolates tend to be multidrug resistant
grow on most media and may resemble enterics on MCA and EMB agars
produce acid from glucose but others don’t
non motile
oxidase (-)
nitrate (-)
catalase (+)
acinetobacter
causes tularemia
potential agent of bioterrorism
carried by wild animals, including deer, rabbits, beavers and squirrels
intracellular bacteria that resist phagocytosis
causes skin ulcers at the site of inoculation and can cause of infections of the lymph nodes, eyes, lungs and GI system
biosafety level 3 is required when handling the organism or suspect specimens
faintly straining coccobacilli
medium of choice: glucose-cyseine blood agar
color morphology: small and grayish
agglutination and direct fluorescent antibody test are used to confirm the identification
francisella tularensis
also known as undulant fever
symptoms may show up anytime from a few days to a few months after you’ve been infected, which include fever, chills, loss of appetite, sweats, weakness, fatigue, joint, muscle and back pain, headache
humans acquire the infection by drinking contaminated milk or from slaughter house
incubation period is 1-3 weeks
brucellosis
causes brucellosis
normal GI flora of animals
facultative intracellular parasite
biosafety level 3 organism
isolated from blood and bone marrow
fastidious organism that will grow on special media like Thayer Martin agars and require 10% CO2 in humidified air and 3-4 weeks for growth
strict aerobe
oxidase (+)
catalase (+)
brucella
4 species of brucella that infect humans
B. melitensis
B. abortus
B. suis
B. canis
inhabits the mucous membranes of the respiratory tract of humans
grows on Bordet-Gengou (potato infusion) and Regan-Lowe agars (charcoal-horse-blood agar) with cephalexin
colonies are small and smooth, appear like mercury droplets and are beta hemolytic
gram (slow minute), poorly stained coccobacilli, single or in pairs
causes pertussis
urease (-)
does not grow on MCA
bordetella pertussis
other species of bordetella
causes mild respiratory infections in humans
grows on MCA
urease (+)
B. parapertussis
other species of bordetella
causes kennel cough in dogs and is an infrequent cause of respiratory infections in humans
grows on MCA
urease (+)
B. bronchiseptica
found mostly as oral flora of animals
infections are caused by animal bites, which can result in cellulitis
grows well on SBA and chocolate agar but will grow on MCA
produce colonies that show star-like centers
most are catalase (+)
glucose (+)
actinobacillus spp.
associated with endocarditis, gum disease
A. actinomyecetemcomitans
normal respiratory/GI flora of animals
causes cellulitis but can progress into osteomyelitis, meningitis, joint infections and pneumonia
grows well on non selective agars but no MAC
oxidase (+)
catalase (+)
indole (+)
nitrate (+)
non motile, pleomorphic, G (-) coccobacilli that may show bipolar staining
penicillin (S)
pasteurella
normal flora of the mouth and upper respiratory tract
causes abscesses of oral cavity and human bite wound infectious
approximately 50% of the strains corrode or pit the agar surface
produces bleach-like odor
eikenella corrodens
what does eikenella corrodens require for growth
hemin (factor X)
first discovered in 1976 as the cause of pneumonia in people attending an American Legion Convention in Philadelphia
aquatic organisms that may be found in various water systems, including humidifiers, whirlpools and air conditioning chillers
resistant to commonly used concentrations of chlorine
legionella
primary pneumonia
severe form of legionellosis
Legionnaires disease
mild form of Legionellosis
characterized by flu-like symptoms
Pontiac fever
most common laboratory assay used for the diagnosis of legionellosis
urine antigen test
gram stain: thin, poorly staining G(-) bacilli; better use 0.1% basic fuchsin as the counter stain instead of safranin
require L-csyteine for growth
grow on BCYE aga but not on SBA
asaccharolytic, most biochemical tests are negative
autofluoresce when exposed to UV light
legionella
found in water and soil
produces a purple or violet pigment on nutrient agar
causes wound infections acquired from contaminated soil or water
chromobacterium
very small Gram variable coccobacilli
considered normal vaginal flora
associated with bacterial vaginosis, UTIs, PID and postpartum sepsis and may infect the newborn
catalase (-)
gardnerella vaginalis
presence of clue cells, epithelial cells with numerous bacteria attached
bacterial vaginosis
scoring system used to diagnose BV
cultures alone are too sensitive but 50-60% of women who do not meet the criteria for BV are positive for G. vaginalis
Amsel and Nugent
oxidase (-)
G (-), curved bacilli
bartonella
agent of trench fever
also causes growth of neoplastic blood vessels in various parts of the body (bacillary angiomatosis) and other infections such as endocarditis
bartonella quintana
causes cat-scratch disease and also bacillary peliosis hepatitis and bacillary angiomatosis
bartonella henselae
found as normal flora in humans in the upper respiratory tract and possibly the GI and genital tract
mainly associated with endocarditis
gram stain: short chains or rosettes of irregularly staining bacilli with bulbous ends
requires CO2 for initial isolation and can be recovered on SBA although growth is enhanced in media containing yeast extract
oxidase (+)
catalase (-)
indole (+, weakly)
cardiobacterium hominis
found as normal oral flora in rats and other rodents
best isolated from blood, synovial fluid and abscess material
non motile
facultative
G (-) pleomorphic bacillus
grows on media enriched with SBA (15% is optimal) incubated in a CO2 incubator
streptobacillus moniliformis
infections following animal bites carrying S. moniliformis
rat-bite fever
ingestion of contaminated food or water with S. moniliformis results in ___
haverhill fever
genus contains about 12 species that are inhabitants of marine water
halophilic except for two species
Vibrio
selective and differential (based on sucrose fermentation) medium that supports the growth of most species and is particularly useful for isolating V. cholerae and V. parahaemolyticus
thiosulfate citrate bile salt sucrose agar (TCBS)
characterized by severe watery diarrhea with flecks of mucus sometimes referred to as “rice-water stool”
cholera
causes a cholera
acquired by ingestion of undercooked seafood or contaminated drinking water
has enterotoxin that alters ion transport of intestinal mucosa, resulting in massive release of water
sucrose (+) and will produce yellow colonies on TCBS agar
vibrio cholerae O1
3 serotypes of of V. cholerae O1
Inaba
Ogawa
Hikojima
2 biotypes of V. cholerae O1
classical
El Tor
important virulence mechanisms of V. cholerae
choleragen
motility
pili
mucinase
causes mild to moderate cholera like diarrhea disease
acquired by eating raw shellfish
important cause of food poisoning in Asia, particularly in Japan and Taiwan
sucrose (-)
V. parahaemolyticus
highly virulent, causing septicemia after ingestion of undercooked seafood, notably raw oysters
causes rapidly progressive wound infection after exposure to marine water
V. vulnificus
very common in marine environment
suspected causes of otitis media and wound infections
V. alginolyticus
found in fresh and salt water
infects humans and fish
causes cellulitis and diarrhea
generally cause a self-limiting infection not usually requiring treatment; however, wound infections may require antimicrobial therapy
aeromonas
beta-hemolytic
oxidase (+)
citrate (+)
indole (+)
VP (+)
ONPG (+)
A. hydrophila
acquired by eating undercooked seafood
primarily associated with a self-limiting gastroenteritis
oxidase (+)
plesiomonas shigelloides
major cause of food poisoning causing gastroenteritis, diarrhea and septic arthritis
acquired by eating undercooked contaminated poultry or other meat products
curved bacilli that may appear S-shaped or spiral on Gram stain
microaerophilic
do not oxidize or ferment carbohydrates and most human isolates are catalase (+) and oxidase (+)
wet mount: darting motility
campylobacter
causes peptic and and duodenal ulcers and has been linked to stomach cancer
microorganisms can be isolated from gastric biopsy on SBA, Brucella, and Skirrow’s incubated microaerophilically
fecal antigen detection, urea breath test and demonstration of urease activity in stomach biopsy material
helicobacter pylori
slender, non motile, non-spore forming, obligate aeorobes
resist gram staining because of lipids in their cell wall that prevent penetration of crystal violet and safranin
acid fast bacilli (AFB)
mycobacteria
primary stain in the acid fast stain
carbolfuchsin
Ziehl Neelsen stain requires ___ during the staining step whereas the Kinyoun’s stain does not
heating
used in decontamination of sputum samples
2% NaOH with N-acetyl-L-cysteine (NALC)
mucolytic agent that liquefies mucus in respiratory specimens, releasing mycobacteria
NALC
increases the pH to a level that is antibacterial
NaOH
solid media for growing mycobacteria: contains egg components for growth and malachite green to inhibit the growth of normal flora
lowenstein-jensen
solid media for growing mycobacteria: made selective by the addition of penicillin and nalidixic acid, and supplemented with RNA
lowenstein-jensen gruft
solid media for growing mycobacteria: agar based and contains 2% glycerol to support the growth of mycobacterium avium complex
middlebrook medium
often used to maintain stock cultures and prepare isolates for biochemical tests
middlebrook 7H9 broth
made by Becton Dickinson
contains modified 7H( broth
large amount of oxygen in the broth quenches the fluorescence of a fluorochrome
mycobacterium growth index tube (MGIT)
contains a radioactively labeled substrate that can be metabolized by mycobacteria
growth of mycobacteria releases radioactive CO2 that is detected by the instrument
BACTEC 460TB
except for members of the M. tuberculosis complex, the mycobacteria are placed into these groupings according to their growth rate and photoreactivity
but due
runyon group
runyon group 1
slow growers and photochromogen
runyon group 2
slow growers and scotochromogen
runyon group 3
slow growers and non chromogen
runyon group 4
rapidly growing mycobacteria
produce yellow to orange pigment only when exposed to light
photochromogen
produce yellow to orange pigment in the light and in the dark
scotochromogen
do not produce pigment
non chromogen
biochemical test for identification of mycobacteria: a suspension of a mycobacterium spp is heated at 68 deg C for 20 minutes then a 1:1 mixture of 30% hydrogen peroxide and 10% Tween 80 is added. after 5 minutes, the suspension is observed for bubbles
M. tuberculosis complex are negative
heat-sensitive catalase
biochemical test for identification of mycobacteria: a 1ml aliquot of a mixture of hydrogen peroxide and Tween 80 is added to a 2-week-old culture deep of mycobacteria and after 5 minutes, the height of the column of bubbles is measured
M. tuberculosis complex produces columns of bubbles <45mm
semiquantitative catalase
biochemical test for identification of mycobacteria: NaNO3 is added to a heavy suspension of mycobacteria, which is then incubated for 2 hours at 35degC and then this is added
___ color is positive reaction
nitrate
pink
M. tuberculosis is one of the few species positive for the accumulation of ____
niacin
because of their slowly growing nature, these are becoming more common in clinical laboratories for the identification for the mycobacteria
nucleic acid assays
causes tuberculosis, chronic primarily lower respiratory tract disease
spread by person-to-person contact via infected droplets, dust
only a few bacteria are necessary to cause disease
mycobacterium tuberculosis
infection begins in the middle or lower areas of the lungs
bacteria can spread in the lymphatic system, CNS and heart
macrophages phagocytize the bacteria and form multinucleated cells, which are eventually surrounded by fibroid cells and later on can calcify
primary tuberculosis
granulomatous lesions in primary tuberculosis which can be seen on CXR
tubercles
calcified granulomatous lesions
ghon-complexes
bacteria are contained within the granulomas and the patient is typically asymptomatic
latent infection
occurs in people with who have had latent TB
alteration in the cell-mediated immune response triggered by poor nutrition, alcoholism or hormonal factors associated with pregnancy and diabetes
reactivation or secondary TB
first line drugs for treating secondary TB
isoniazid
rifampin
ethambutal
pyrazinamide
resistance to any fluoroquinolone, and at least one of three injectable second-line drugs in addition to isoniazid and rifampicin
extremely-drug-resistant M. tuberculosis
skin test that determines exposure to M. tuberculosis
Ag is composed of heat-killed, filtered, ammonium sulfate precipitated protein
injected intradermally and is examined at 48 hours for swelling
positive test indicates previous exposure
purified protein derivative (PPD)
agent of Hansen disease
cannot be grown on artificial media
diagnosis is based on characteristic skin lesions and visualizing AFB in lesion
mycobacterium leprae
may cause disseminated disease in immunosuppressed patients such as patients with human immunodeficiency virus infection, producing lung infection, lymphadenitis and intestinal infection
slowly growing non chromogen
mycobacterium avium complex (MAC)
causes pulmonary infection and is the most commonly isolated photochromogen in US
causes a lung disease that resembles classic TB and rarely disseminates, except in patients with severe immunosuppression
slow grower
nitrate (+)
catalase (+)
mycobacterium kansasii
causes cervical lymphadenitis and other types of infectious predominantly in children
slowing growing scotochromogen
mycobacterium scrofulaceum
implicated in skin infections
predilection for surface areas and extremities of the body is related to their optimal growth temperature range of 30-32 deg celsius
M. ulcerancs
M. marinum
M. haemophilum
responsible for a zoonosis, producing pulmonary infections primarily in cattle and occasionally in humans
non chromogen like M. tuberculosis
nitrate (-)
niacin (-)
T2H (S)
M. bovis
may cause abscesses, osteomyelitis, wound and lung infection
weakly virulent
rapidly growing mycobacteria
M. fortuitum
M. chelonae
M. abscessus
found in fresh water, including tap water
rarely pathogenic
slow growing scotochromogen often isolated as a contaminant
M. gordonae
comprise most normal flora of the mucous membranes
foul odor (from gas production) and necrotic tissue
anaerobic body sites, abscesses and wound
surgical specimens
anaerobic bacteria
bacterium that cannot use oxygen for metabolism and oxygen is lethal to the microorganism
obligate anaerobe
bacterium that cannot use oxygen but can grow in its presence
aerotolerant anaerobe
bacterium that will use oxygen if its present and can grow, albeit more slowly, without oxygen
facultative anaerobe
bacterium that requires oxygen at a concentration found in room air, about 20%
obligate aerobe
bacterium that requires oxygen at a concentrations of 5-10%
microaerophile
bacterium that requires increased concentrations of CO2
capnophile
being added to the anaerobic media to enhance the growth of Prevotella and Porphyromonas
vitamin K
being added to the anaerobic media as enrichment for Bacteroides and Prevotella
hemin
anaerobic media: for general growth of all anaerobes
centers for disease control and prevention (CDC) anaerobic blood agar
anaerobic media: selective and differential medium used to culture and presumptively identify Bacteroides fragilis
bacteroides bile esculin (BBE) agar
anaerobic media: enriched selective medium for isolation of slowing growing anaerobes such as Prevotella and Bacteroides, which contains component that enhances pigment formation
kanamycin-vancomycin laked sheep blood (KVLB) agar
anaerobic media: enriched and selective medium used for growth of facultative, anaerobic, gram negative bacilli
phenylethyl alcohol (PEA) agar
tapwater bacillus
mycobacterium gordonae
anaerobic media: inhibits gram neg organism and is used to grow most gram positive anaerobes and facultative anaerobes
columbia-colistin-naladixic agar with 5% sheep blood
anaerobic media: used to detect proteolytic enzyme produced by clostridium
lecithinase activity produces an opaque zone for the cleavage of lecithin, releasing insoluble fats
lipase cleaves lipids, releasing glycerol, which floats to the top of the medium producing a blue-green sheen on the agar surgace
egg yolk agar
must be used to determine if anaerobic conditions have been met
oxidation-reduction indicator
most commonly used oxidation-reduction indicator
will turn from blue (oxidized) to white indicating reduction
methylene blue
before attempting to identify a possible anaerobic bacterium, it fist must be demonstrated to be an obligate anaerobe
a colony is inoculated to an anaerobic blood agar plate, which is incubated anaerobically, and to a chocolate agar plate incubated under conditions of increased CO2
aerotolerance testing
pale pleomorphic gram (-) coccobacilli with bipolar staining
bacteroides
prevotella
long, thin, filamentous, gram (-) bacilli with tapered ends arranged end to end
fusobacterium
branching gram (+) bacilli
actinomyces
large gram (+) bacilli, spore location is important for identification
clostridium
non pigmented bacillus responsible for most anaerobic infections, and many isolates are becoming more resistant to antimicrobial agents
major normal flora of the colon
causes infections by gaining entry into normally sterile body sties, especially after surgery, trauma or disease
non motile, gram (-) bacilli with rounded ends and may be pleomorphic
non hemolytic on anaerobic blood agar
growth in 20% bile
catalase (+)
lipase (-)
bile-esculin (+)
lecithinase (-)
geletinase (-)
bacteroides fragilis
important virulence mechanism of bacteroides fragilis
polysaccharide capsule
pigmented saccharolytic gram (-) bacilli
normal flora of the oropharynx, nose and GI and urogenital tracts
causes head, neck and lower respiratory tract infection
young colonies appear tan and exhibit brick-red fluorescence under UV light (older colonies are brown and black)
ferments glucose and many other carbohydrates and is inhibited by 20% bile
prevotella melaninogenica
what antibiotics B. fragilis is resistant to
penicillin
kanamycin
vancomycin
what antibiotics B. fragilis is susceptible to
rifampin
asaccharolytic or weak fermenters, pigmented colonies, gram negative bacilli
normal flora of the oropharynx, nose and GI and urogenital tracts
causes infections of the head, neck, oral cavity and urogenital tracts
brick red fluorescence under UV light
porphyromonas spp
asaccharolytic or weak fermenters, non pigmented colonies, gram negative bacilli
normal flora of the upper respiratory and GI tracts
cause pulmonary, blood, sinus and dental infections in addition to brain abscesses
associated with metastatic conditions
colony morphology; opalescent with speckles
indole (+)
lipase (+)
nitrate (-)
catalase (-)
relatively biochemically inactive
fusobacterium
growth of porphyromonas is inhibited by ____ but they are resistant to ___
bile, vancomycin, penicillin and rifamipin
kanamycin
inhibit growth of fusobacterium
kanamycin
colistin
fusobacterium is resistant to ___
vancomycin
causes serious pulmonary infections
more common isolate
asaccharolytic or weak fermenters, non pigmented colonies, gram negative bacilli
colony morphology; opalescent with speckles
indole (+)
lipase (+)
nitrate (-)
catalase (-)
relatively biochemically inactive
fusobacterium nucleatum
causes lung and liver abscesses and arthritis
more serious infection
asaccharolytic or weak fermenters, non pigmented colonies, gram negative bacilli
colony morphology; opalescent with speckles
indole (+)
lipase (+)
nitrate (-)
catalase (-)
relatively biochemically inactive
fusobacterium necrophorum
causes gas gangrene, post-abortion sepsis, abdominal infections and enterocolitis
major cause of food poisoning resulting in mild to moderate diarrhea without vomiting
acquired through puncture wound or by ingestion
normal flora of the GI tract and can spread from this site following trauma
normal flora of the female genital tract and can cause post-abortion infections
clostridium perfringens
produces a double zone of beta hemolysis on SBA incubated anaerobically
positive reverse CAMP test
lecithinase (+)
glucose (+)
lactose (+)
maltose
fructose (+)
subterminal spores
non motile
clostridium perfringens
anti-lecithincase antibody is swabbed onto half of an egg yolk agar plate
isolate is inoculated onto both halves of the plate
nagler test
