Micro Clinical Review Flashcards
Gram negative, rod-shaped, and facultative anaerobe.
Catalase: +
Oxidase: -
Indole: +
MR: +
VP: -
Citrate: -
Nitrate: +
PYR: -
TSI: A/AG
Urease: -
Lactose: F
Decarboxylase: L+
MUG: +
ONPG: N/A
Escherichia Coli
Opportunistic, causes UTI, neonatal meningitis, wound infections, and septicemia.
Gram negative, rod-shaped, encapsulated, nonmotile.
Oxidase: -
Indole: -
MR: -
VP: +
Citrate: +
Nitrate: +
TSI: A/AG
Urease: +
Lactose: F
Decarboxylase: L+, O-
MUG: +
ONPG: +
Klebsiella pneumonia
Enterobacteriaceae family. Causes nosocomial infections including UTI, bloodstream infections, lower respiratory tract, cardiovascular, wound, ear, nose, and throat infections.
Gram negative rods. Motile.
Oxidase: -
Indole: V
MR: +
VP: -
Citrate: +
Nitrate: +
TSI: A/AG, H2S
Urease: V
Lactose: F (late)
Decarboxylase: L-,O-
MUG: N/A
ONPG: N/A
Citrobacter freundii
Enterobacteriaceae family. Natural intestinal microflora, but causes UTI.
Gram negative rods. Motile. Facultative anaerobe.
Oxidase: -
Indole: -
MR: V
VP: V
Citrate: +
Nitrate: +
TSI: A/A (+/-G)
Urease: +
Lactose: F
Decarboxylase: N/A
MUG: N/A
ONPG: N/A
Serratia marcescens
Family Enterobacteriaceae. Opportunistic, causing nosocomial respiratory, UTI, or blood infections.
Red pigment called prodigiosin.
Gram negative rod.
Indole: -
MR: -
VP: +
Citrate: +
TSI: A/A (+/-G)
Urease: -
Lactose: F
Decarboxylase: Triple (-)
MUG: N/A
ONPG: +
Enterobacter
Lactose fermenter
Pantoea
Gram negative rods, peritrichous flagella (motile).
Indole: -
MR: +
VP: -
Citrate: -
TSI: K/AG, H2S
Urease: -
Lactose: NF
Decarboxylase: L+
MUG: -
ONPG: -
Salmonella
Causes salmonellosis, typhoid fever (S. typhi), or paratyphoid fever (S. paratyphi).
Gram negative rods, non-motile, non-spore forming.
Oxidase: -
Indole: V
MR: +
VP: -
Citrate: -
Nitrate: +
TSI: K/A
Urease: -
Lactose: NF
Decarboxylase: L- (sonnie = O+)
MUG: N/A
ONPG: - (sonnie = +)
Shigella
Enterobacteriaceae family. Causes shigellosis, traveler’s diarrhea.
Gram negative, rod-shaped, facultative anaerobe. Swarms on colonies (motile).
Oxidase: -
Indole: -
MR: ++
VP: - -
Citrate: - (v)
Nitrate: +
TSI: K/A, H2S
Urease: + strong
Lactose: NF
Decarboxylase: O+
MUG: N/A
ONPG: N/A
Proteus mirabilis
Causes cystitis and pyelonephritis.
Indole: +
MR: +
VP: -
Citrate: -
TSI: K/AG
Urease: +
Lactose: NF
Decarboxylase: N/A
MUG: N/A
ONPG: N/A
Morganella
Indole: +
MR: +
VP: -
Citrate: +
TSI: K/A (+/-G)
Urease: -
Lactose: NF
Decarboxylase: N/A
MUG: N/A
ONPG: N/A
Providencia
Indole: -
MR: +
VP: -
Citrate: -
TSI: K/K
Urease: -
Lactose: NF
Decarboxylase: O-
MUG: N/A
ONPG: N/A
Yersinia Pestis
Almost all
Catalase: +
Nitrate: +
Oxidase: -
Enterobacteriaceae
What microbes use the Phenylalanine Deaminase Test (PAD test)
Differentiates Proteus, Morganella, and Providencia from other Enterobacteriaceae.
Test determines if the organism is able to produce deaminase enzyme, which removes the amine group phenylalanine. When it is removed, it is released as ammonia and phenyl pyruvic acid is produced.
Positive = dark green
Negative = No color change
*Note: most stool pathogens are urease negative.
What are the principles of the: catalase test?
The production of catalase turns hydrogen peroxide into water and oxygen.
What are the principles of the: Oxidase test?
What are the principles of the: Coagulase test?
What are the principles of the: DNAse test?
The ability of an organism to digest DNA.
What are the principles of the: Hippurate hydrolysis test?
What are the principles of the: Bile esculin hydrolysis test?
What are the principles of the: CAMP test?
What are the principles of the: bile solubility test?
Differentiates Strep pneumoniae from alpha-hemolytic streptococcus.
S. pneumoniae will lyse in the presence of bile salts where other streptococcus will not.
What are the principles of the: IMViC test?
A mix of Indole, methyl red, Vogue’s Proskauer, and citrate testing.
What are the principles of the: TSI test?
The TSI (triple iron agar) test is used to differentiate bacteria based on carbohydrate fermentation (lactose, glucose, and sucrose).
Glucose is on the bottom, sucrose and lactose on the top.
Also detects hydrogen sulfide production.
What are the principles of the: nitrate test?
Nitrate –> nitrite –> nitrogen, nitrous oxide, or nitric oxide.
Nitrite + sulfanilic acid (reagent A) + alpha naphthylamine (reagent B) –> red complex (prontosil).
If zinc powder results in a red color change, then no reduction took place.
If zinc powder results in no color change, then nitrate was reduced to nitrogen.
What are the principles of the: LIA test?
The LIA (lysine iron agar) test determines glucose fermentation.
When glucose is fermented, the butt of the tube becomes yellow (acidic).
If the organism produces lysine decarboxylase, then cadaverine (acid neutralizer) is formed and butt of the tube becomes purple (alkaline).
Gram negative, rod-shaped, motile.
Catalase: +
Oxidase: -
Indole: -
MR: -
VP: +
Citrate: +
Nitrate: +
TSI: A/A or A/AG
Lactose: F
Intrinsic resistance to ampicillin, amoxicillin, and 1st and 2nd generation cephalosporins.
Enterobacter cloacae complex
Naturally found in GI, but causes Nosocomial infections outside GI. UTIs, wound infections pneumonia, and bacteremia.
Gram negative rod. Polar flagella (motile), and non-spore forming.
Catalase: +
Oxidase: +
Nitrate: +
TSI: K/NC
Lactose: NF
Pseudomonas aeruginosa
Nosocomial infections. Causes folliculitis, otitis externa, otitis media, eye infections, and traumatic wound infections.
Respiratory infections in cystic fibrosis patients.
Gram negative rods. Curved, motile, and halophilic (obtained from shellfish, crabs, shrimp, and prawns).
Catalase: +
Oxidase: +
Indole: +
TSI: K/A
Lactose: NF
Nitrate: +
Decarboxylase: L +
Deaminase: O +
What does the string test differentiate?
Vibrio
Acute diarrhea and wound infections.
Vibrio cholera has cholera toxin causing watery diarrhea and dehydration.
Differentiates Vibrio cholera (+) from other Vibrio spp (-).
Gram negative bacillus, aerobic and non-fermentative. Motile with polar flagella.
Catalase: +,
Oxidase: -
DNAse: +
Stenotrophomonas maltophilia
Found in various aquarium environments, soil and plants.
Nosocomial.
Causes: bacteria, Meningitis, UTI, endocarditis,
keratitis, lower respiratory tract infection in patient with cystic fibrosis
Gram negative rods,
Resistance to ampicillin, aztreonam and gentamicin.
Colonies are white with a thin, spreading irregular edge.
Oxidase: +
Indole: -
Asaccharolytic nonfermenters.
Which can reduce nitrite, but not nitrate?
Which can reduce both?
Alcaligenes faecalis & Alcaligenes-like group 1
Found in water, soil, and moist areas.
A. Faecalis is the most common isolated species and is an occasional cause of nosocomial
infections (UTI’s, pneumonia and septicemia).
A. faecalis can reduce nitrite but not nitrate while CDC Alcaligenes-like group 1
can reduce both nitrate and nitrite
Gram negative bacillus that may appear curved (seagull) with single polar flagellum.
Microaerophilic.
Campy-BAP: Grey to white, moist colonies.
Catalase: +
Oxidase: +
Nitrate: +
Hippurate: +
Negative:
H2S: -
Growth on 3.5% NaCl: -
Unique characteristics – grows best at 42C
Campylobacter jejuni
Campylobacteriosis – most common foodborne diarrheal illness in the US.
Symptoms: bloody diarrhea, fever, cramps, nausea, vomiting. Self limiting, but some antibiotic resistant strains have been observed. Associated with Guillain-Barre syndrome (GBS) and Reiter’s Syndrome.
Gram negative coccobacilli that has small, pinpoint colonies that are grayish and has
a bleach smell when grown on blood agar. Non-motile, non-spore forming.
Oxidase: +
Catalase: -
Indole: -
Urease: -
Nitrate: +
Eikenella corrodens
Normal microflora in the mouth, upper respiratory tract and other mucosal sites in the body. It is commonly found with streptococci. It is an opportunistic pathogen associated with human bites, dental extractions or oral trauma.
Gram-negative bacilli with variable shape. Small.
Nonmotile, non-spore forming, facultative anaerobes. Fastidious. Non- hemolytic.
Nitrate reduction: +
δ- aminolevulinic acid test: - (does not fluoresce)
Chocolate agar: grayish, semi-opaque, smooth and flat colonies
Blood agar: no growth
Encapsulated strains: dense growth
Non-encapsulated strains: separate colonies
Indole producing strains have a pungent aroma
Non-indole producing strains have a “mouse nest” odor
Quad Plate: ???
Many strains are resistant to ampicillin, other β-lactam antibiotics,
chloramphenicol, and tetracyclin.
Haemophilus influenzae
Causes bacterial meningitis, purulent bacterial conjunctivitis, otitis media, sinusitis, and lower respiratory tract infections.
Antiphagocytic due to polysaccharide capsule.
H. influenzae = X factor (hemin) & V factor (NAD) for growth
o δ- aminolevulinic acid test: negative (does not fluoresce)
o Additional methods: Rapid NH or MALDI-TOF
Gram negative, coffee-bean shaped diplococci
Catalase: +
Oxidase: +
Glucose: F
Maltose: F
Nitrate: -
Grows on blood agar, chocolate agar and Thayer martin agar.
Neisseria meningitidis
Has many virulence factors: pili, IgA protease, produces an endotoxin,
and has a capsule.
Causes Meningococcal disease spread by respiratory droplets from an infected person. Causes inflammation of the meninges. Anyone can be infected, but the highest rate worldwide is in
the “meningitis belt” in sub-Sarahan Africa
Gram negative, diplococci
Glucose: F
Maltose: NF
Lactose: NF
Nitrate: -
0.1% nitrite reduction: -
Growth on modified Thayer-Martin
No growth on nutrient agar at 35°C, No growth on blood or chocolate agar at 25°C
Neisseria gonorrhoeae
Transmitted sexually or during birth.
Causes acute cervicitis in females and acute purulent urethritis, prostatitis, epididymitis in males.
Can also cause pharyngitis, anorectal infections, and conjunctivitis. Disseminated infections can include pelvic inflammatory disease, bacteremia, arthritis, and
metastatic infection.
Gram negative diplococci (coffee bean).
Smooth, large, round, pinkish-brown opaque hockey puck colonies.
Catalase: +
Oxidase: +
Nitrate: +
DNAse: +
MCAT: +
Growth on chocolate agar.
Moraxella catarrhalis
Respiratory tract infections:
Upper RT = otitis media, sinusitis, and pneumonia
Lower RT = COPD
Gram positive cocci in clusters. Facultative anaerobic.
Catalase: +
Coagulase: -
No hemolysis
Staphylococcus epidermidis
Nosocomial infections: UTI
Gram positive cocci in clusters.
Catalase: +
Coagulase: +
DNAse: +
Staphylococcus aureus
Causes toxic shock syndrome, scalded skin syndrome, food poisoning, skin infections, bacteremia, endocarditis, pneumonia, and osteomyelitis.
Gram positive cocci in chains.
Vancomycin: S
LAP: +
PYR: -
Coagulase: -
Catalase: -
Streptococcus viridans group
Found as normal flora.
Group includes mitis, salivarius, bovis, mutans, and anginosus
Gram positive cocci, facultative anaerobes.
Blood agar: smooth, gray colonies with alpha or gamma hemolysis.
Catalase: -
Oxidase: -
Esculin hydrolysis: +
PYR: +
Enterococcus faecalis & Enterococcus faecium
Nosocomial UTIs, bacteremia, pelvic and wound infections, and endocarditis.
Which ferments mannitol?
Gram positive cocci in chains.
Large, mucoid colonies.
Beta hemolysis.
Catalase: -
PYR: +
Bacitracin: S
Streptococcus pyogenes (group A)
Causes pharyngitis, impetigo, and erysipelas, scarlet fever, toxic shock syndrome, necrotizing fasciitis, glomerulonephritis, rheumatic fever, and carditis.
Gram positive cocci in chains. Facultative anaerobe.
Non-motile, non-spore forming.
Beta hemolytic.
Catalase: -
CAMP: +
Hippurate: +
Bile esculin: -
Streptococcus agalactiae
Causes meningitis, septicemia, endocarditis, osteomyelitis, pneumonia, skin and soft tissue infections.
Gram positive cocci in pairs.
Alpha hemolysis.
Catalase: -
Bile solubility: +
Optochin: S
What does the Quellung test do?
Streptococcus pneumoniae
Causes pneumonia, otitis media, meningitis, and septicemia.
Quellung test helps visualize capsule.
Listeria monocytogenes
Corynebacterium spp
Nocardia
Brucella
Francisella
Burkholderia mallei
Burkholderia pseudomallei
Bacillus anthracis
Gram negative rods, aerobic, peritrichous flagella (motile).
Lactose: NF
Xylose oxidizer
Achromobacter
Opportunistic and nosocomial infections of urinary and respiratory tract.
