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72 Cards in this Set
- Front
- Back
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Staphylococcus aureus characteristics / tests
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Beta hemolytic. Beta-lactamase production. Catalase, coag, and VP positive. PYR neg. Bacitracin resistant. Ferments mannitol (yellow colonies on MSA). Protein A.
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Staphylococcus aureus
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Isolated from abscesses, wound infections, and carbuncles. Resident flora in nose and skin. Causes food poisoning (enterotoxin), pneumonia, endocarditis, and scalded skin syndrome.
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Coag-neg Staph
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Common skin bacteria. Mostly nonpathogenic. Nonhemolytic.
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Staphylococcus epidermidis
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Most common species of coag neg Staph. Novobiocin susceptible
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Staphylococcus saprophyticus
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Significant only in UTIs. Novobiocin resistant
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Staphylococcus lugdunensis
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Usually beta hemolytic. Similar morphology to S. aureus. Clumping factor positive, but tube coag negative.
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Micrococcus
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Nonpathogen. Normal isolate of skin and mucus membranes. Gram positive, catalase positive. Arranged in tetrads on Gram stain. M. luteus is usually a contaminate found on skin (bacitracin sensitive).
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Streptococcus
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Catalase negative. Many alpha/gamma are normal flora in skin, respiratory, mucosal surfaces, and female genital tract. Beta hemolytic can cause infections
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Streptococcus pyogenes
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Group A. Beta hemolytic zone > colony size. PYR positive. Susceptible to bacitracin (A disk). Resistant to SXT. Has M protein.
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Infections caused by S. pyogenes
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Always pathogenic and spread by respiratory secretions.
Bacterial pharyngitis (strep throat), impetigo (skin infection), rheumatic fever, glomerulonephritis, Scarlet fever (red rash), otitis media, and necrotizing fasciitis. |
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Streptococcus agalactiae
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Group B. Normal flora of GI tract. Beta hemolytic zone < colony size (>1mm). Resistant to SXT, PYR neg, Bacitracin resistant, cAMP test positive.
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Infections caused by S. agalactiae
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Neonatal sepsis, meningitis. Reason for routine testing of pregnant women at 35-37 wks.
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Enterococcus
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Group D Strep. Normal fecal and oral flora. Causes wound infections, UTI, endocarditis. Positive for bile-esculin, 6.5% NaCl, and PYR.
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Streptococcus bovis
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Group D strep (non-enterococcus). Negative for 6.5% NaCl. Bile-esculin positive.
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Viridans streptococcus
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Alpha hemolytic. butterscotch smell, VP positive, Optochin resistant. Bile esculin negative.
Associated w/ abscess formation. Major cause of bacterial endocarditis. May enter blood after dental procedures. |
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Streptococcus pneumoniae
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Alpha hemolytic. Lancet-shaped diplococci. Depressed centers of colonies d/t autolytic enzymes. Sometimes mucoid (d/t capsule). Normal respiratory flora, but can cause otitis media in children and community-acquired bacterial pneumonia. Optochin sensitive.
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Neisseriaceae family
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Gram negative diplococci, catalase positive, oxidase positive, capnophilic. Cannot tolerate cold (must bring to RT before plating). Include Neisseria, Acinetobacter, Kingella, and Moraxella
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Neisseria gonorrhoeae
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Always a pathogen. Not normal flora. Urogenital specimens. Adheres to mucosal cells w/ pili. Does not grow on BAP but grows on choc. Requires CO2 w/ humidified atmosphere. Nitrate negative.
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Neisseria gonorrhoeae infections
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Males: 95% symptomatic. Urethra discharge. Dx: Gram stain showing WBCs.
Females: 50% symptomatic. Untreated results in pelvic inflammatory disease. Endocervical is specimen of choice. |
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Neisseria meningitidis
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Normal upper respiratory flora. Transmitted by aerosols. Recovered in blood, CSF, other sterile sites. Easily cultured on BAP/CHOC. Vaccine available. Nitrate negative.
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Moraxella catarhalis
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Resembles Neisseria. Normal flora of upper resp tract. Causes otitis media, sinusitis, and resp tract infections. Nitrate and butyrate esterase positive.
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Enterobacteriaceae
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Short, fat Gram neg bacilli. Normal GI flora except Salmonella and Shigella. All oxidase negative and positive for glucose and nitrate.
Include: E.coli, Kleb, Enterobacter, Serratia, Salmonella, Shigella, Proteus, Yersinia, Edwardsiella, Citrobacter, Morganella, Providencia |
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Escherichia coli
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TSI: A/A
H2S and citrate negative. Indole positive. EMB: green metalic sheen colonies w/ dark centers |
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Enterotoxigenic E. coli
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Traveler's diarrhea (severe epidemic diarrhea). Noninflammatory. Contaminated water. No fecal leukocytes present.
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Enteroinvasive E. coli
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Produce dysentery. Invade and destroy colon cells (large intestines). Fecal leukocytes present.
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Enteropathogenic E. coli
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Infantile diarrhea. Ability to adhere. Causes watery diarrhea.
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Enterohemorrhagic E. coli
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0157:H7, produces shiga toxin. Food poisoning.
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E. coli 0157:H7
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Hemorrhagic colitis and HUS, leading to kidney failure in young children. Does not metabolize sorbitol, so appears colorless on Sorbitol-MacConkey (SMAC).
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Klebsiella
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Cause pneumonia and UTIs. Very mucoid colonies on BAP or MAC. Produces jelly like thick sputum.
TSI: A/A with gas Positive: urease, citrate |
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Enterobacter
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Found in soil, water, and dairy products. A/A with gas. Indole and urease negative.
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Serratia
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Opportunistic infection in chemotherapy and immunosuppressed pts.
TSI: K/A DNAase, lipase, and citrate positive. H2S and indole negative |
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Salmonella
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Moderate-severe gastroenteritis. Self limiting. Serotypes based on antigens O (cellular), Vi (capsular), and H (flagellar).
TSI: alk slant / black stab HE agar: green w/ black centers |
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Shigella
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Shigellosis (bacterial dysentery). VERY pathogenic (<50 bacteria can cause disease). Food poisoning by fecal contamination from infected humans. Does not enter bloodstream (antidiarrheal medications do NOT work). Serogroups based on O antigens (DFBS = groups ABCD)
TSI: K/A. Motility and H2S negative. |
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Proteus
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Swarming on BAP. Strongly urease positive.
TSI: K/A w/ gas H2S and rapid urease positive. P. mirabilis is indole neg; P. vulgaris is indole pos |
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Yersinia
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Small coccobacilli. Nonmotile at 37'C, but motile at 25'C.
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Lactose fermenters
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E. coli, Enterobacter spp., Klebsiella spp., Citrobacter spp. (+/-)
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Nonlactose fermenters
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Salmonella, Shigella, Yersinia, Proteus
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Yersinia pestis
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Cause of plague (from fleas). Infects PMNs and macrophages. Only species that is non-motile at RT, grows faster at RT.
Bioterrorism list |
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Yersinia enterocolitica
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Causes enterocolitis from contaminated meat or water. Lactose negative, sucrose positive (colorless on MAC, A/A on TSI). Right side pain in adults often confused w/ appendicitis.
Grows at 4C. CIN selective agar colonies are red bulls-eye. |
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Citrobacter
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C. freundii most common species.
Normal gut flora. Some spp. H2S producers. Variable lactose fermentation. TSI = A / H2S Phenylalanine deaminase negative |
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Morganella
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M. morganii is only species. Phenylalanine deaminase positive.
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Haemophilus
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Small GNR, coccobacillus. Mousy odor.
Small, tan, smooth, and moist looking colonies. Many normal flora of upper resp tract. Oxidase positive, Capnophilic Do not grow on BAP d/t NADase in agar, but will grow on horse/rabbit blood agar and CHOC |
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Haemophilus influenzae
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-Meningitis in children
-Catalase positive -Requires X and V factor for growth |
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Haemophilus influenzae biotype III
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Causes pink eye. Sucrose positive. Previously known as H. aegyptius. Requires both factors.
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Haemophilus parainfluenzae
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Requires V factor, but does not require X factor for growth
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Haemophilus ducreyi
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Causes genital ulcers. Produces chancroids. Requires X factor. Catalase neg.
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Nonfermentative Gram Negative Bacilli/Coccobacilli
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Do not form spores or break down sugars. Most are strict aerobes and oxidase positive. TSI: K/NC. Includes P. aeruginosa, Acinetobacter spp., Stenotrophomonas maltophlia, Burkholderia cepacia
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Pseudomonas aeruginosa
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Leading nosocomial infection of respiratory
tract. Opportunistic pathogen. Swimmer's ear, eye/ear infections, Jacuzzi syndrome, burns, wounds. Blue-green, metallic sheen. Beta hemolysis w/ feathery edge. Large, irregular mucoid colonies w/ grape/tortilla odor. Catalase/oxidase positive. |
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Acinetobacter
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Normal flora of GI and resp tract. Causes nosocomial infections and UTIs. Great pretender. Looks like GPC on Gram stain (ie. Neisseria in vagina/cervical cultures, except oxidase NEG). On MAC looks like lactose fermenter (ie. enterics).
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Stenotrophomonas maltophila
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Associated with IV drug abuse. Contaminates hospital equipment. Causes pneumonia, UTIs, wound infection. Oxidase negative.
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Burkerholderia cepacia
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Cystic fibrosis patients. Selective/differential media used to separate from respiratory specimens (BCSA media). Oxidase positive. Dirt odor.
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Eikenella corrodens
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Exist in dental plaque and can cause infection (bites, dental procedures, etc). Corroding bacterium causes pits to form on surface of agar. Bleach-like odor. Gram neg, non-sporeforming bacillus.
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Francisella tularensis
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Zoonosis. Bioterrorism agent (biosafety level 3 required). Requires cysteine (ex. BCYE or glucose-cysteine blood agar). Gram neg coccobacilli.
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Brucella
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-Bioterrorism agent (type 3 biohazard)
-Normal GI flora of animals -Contaminated milk or slaughterhouse exposure -Oxidase positive -Gram neg coccobacilli -Grows on Brucella, BCYE, and modified Thayer-Martin; requires 10% CO2 and 3-4 wks to grow |
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Bordetella spp.
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Whooping cough (B. pertussis). Appear like mercury droplets and beta-hemolytic. Gram neg coccobacilli.
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Pasteurella spp.
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Animal bites or dried animal fecal inhalation. Brown colonies w/ mushroom smell. Rarely grows on differential media such as EMB or MAC. Catalase/oxidase positive.
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Legionella spp.
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Requires L-cysteine and iron. Special media: BCYE. Caused by pneumonia. Found in water systems. Most biochemical tests are negative, but Legionella is motile.
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Campylobacter spp.
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Food poisoning. Part of routine stool culture. Undercooked poultry or other meats. C. jejuni causes most infections.
-Capnophilic, curved bacilli (S-shaped or spiral), catalase/oxidase positive, nonfermentative, grows on Campylobacter agar at 42-43'C. Darting motility on wet mount. |
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Helicobacter pylori
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Spiral shaped or curved Gram neg non-spore-forming bacilli. Causes peptic and duodenal ulcers. Oxidase, rapid urease, and catalase positive.
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Bacillus spp.
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Spores are frequent contaminants of lab cultures. Most nonpathogenic. Straight bacillus w/ square ends (boxcar morphology). Catalase pos. except for Bacillus anthracis. Pathogenic species include B. anthracis and B. cereus.
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Listeria monocytogenes
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Causes spontaneous abortion and meningitis. Closely resembles Group B Strep on blood agar. Umbrella motility at RT and end over end motility in wet mount.
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Gardnerella vaginalis
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Bacterial vaginosis. Normal anorectal flora. Presence of clue cells (epithelial cells covered w/ bacteria on cell margins). Small, gram-neg rods/coccobacilli.
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Corynebacterium diphtheriae
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Causes diphtheria. Bacterial toxins damage all major organs resulting in high death rate. Picket fence or Chinese letters morphology. Elek is test for toxin production.
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Lactobacillus spp.
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Normal flora of oral cavity, GI, and female genital tract. Rare pathogen. Catalase negative, nonmotile bacilli; tiny colonies on BAP; may show greening around colony.
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Fusobacterium nucleatum
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Anaerobic. Gram stain - pointed (jack straw) gram negative rods; long, thin, filamentous w/ tapered ends arranged end to end
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Clostridium
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Anaerobic Gram positive spore-forming bacilli (boxcar shaped). Catalase negative. Produce true toxins.
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Clostridium perfringens
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Gas gangrene (myonecrosis) and food poisoning. Normal flora of female genital tract. Double zone of hemolysis.
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Clostridium tetani
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Causes tetanus resulting in involuntary muscle contractions (ie. lock jaw). Bacteria and spore gain entry by puncture wounds. Gram stain spores resemble drumsticks.
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Clostridium botulinum
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Food poisoning (ie. canned food) leads to flaccid paralysis. Spores look like tennis rackets.
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Clostridium difficile
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Antibiotic acquired diarrhea (AAD). Common nosocomial infection. Enterotoxin and cytotoxin. Horsebarn odor. Oval spores.
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Mycobacterium
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Slender, nonmotile, non-spore forming, slow growing, acid fast, obligate aerobes. Resist Gram staining d/t cell wall lipids. Produce niacin. Most catalase positive.
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Mycobacterium tuberculosis
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Spread by infected droplets, dust, etc. Only a few bacteria necessary to cause disease. Primary TB begins in lungs. Slow, progressive disease. Can spread and form tubercles.
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