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Micro Week 1
Gen, GPC, GPB, Neisseria, Haemophilus, Branching GPR, Biochems
| Question | Answer |
|---|---|
| Gram staining steps | 1) Violet 2) Iodine (mordant) 3) Alcohol 5) Saffron 6) Rinse |
| Parasite stain | Trichrome |
| Malaria stain | Giesma stain |
| Pneumocystis stain | Fluorescent |
| H. pylori stain | H&E |
| Supportive/Enriched Media | Sustains growth of many organisms; can be fortified to support fastidious organisms |
| Selective Media | Selects for growth of a desired organism while stopping others |
| Differential Media | Leads to a visible change when target organism grows |
| MSA | Selective AND Differential; Staph aureus LOVES mannitol and will consume it, turning pink agar yellow while other Staph are indifferent; Differential due to bile salts |
| BAP | Supportive AND Differential (hemolysis) |
| Choc | Supportive |
| MAC | Differential and selective (Selective due to bile salts; toxic to GP) |
| CNA | Selective for GP (Colistin Nalidixic Acid is toxic to GN) |
| MTM | Seletive; only grows pathogenic Neisseria |
| Lancefield | Immunology typing for beta Strep based on C Carbohydrate |
| Catalase | Drop hydrogen peroxide and see if it bubbles; sees if organism produces catalase, which breaks down H2O2 |
| IMViC Tests | Indole, Methyl Red, Voges-Proskauer In Citrate |
| API Strip | Results get a color and assigned a number combo used for ID |
| Best stage of growth to work with | Exponential |
| Is GP or GN easier to treat? | GP; antibiotics can target the peptidoglycan |
| Antigenic signatures of Staph | Coagulase, TSST-1 (Toxic shock syndrome), Protein A |
| Scalded Skin Syndrome | Rashes, fever in neonates due to mom’s vaginal tract colonized with Staph; exfoliative toxin dissolves mucopolysaccharide matrix of epidermis |
| TSST-1 | Staph exotoxin superantigen that stimulates T cells and induces Tumor Necrotic Factor (TNF) and Cytokinee interleukin-1; Symptoms: Rash, fever, hypotension, shock, multiorgan involvement |
| Protein A | Staph aureus virulence factor that binds to Fc region of immunoglobin, paralyzes WBCs, and activates complement |
| Staph aureus Biochemicals | Cat(+), Coagulase (+), Latex agglutination (Protein A) (+) |
| Coagulase Negative Staph (CNS/CoNS) Species | S. lugenesis and S. schleiferi (generally coag (-) but may have weak clumping); S. saphrolyticus; S. haemolyticus |
| CoNS Biochemicals | Cat (+); Coag (-); Latex agglutination (-); White-gray, nonhemolytic colonies (except for Staph haemolyticus) |
| Staph saprolyticus | CoNS; Female urinary tract; child bearing age; Bright white colonies; Novobiocin disk + (Resistant; zones >16 mm) |
| Novobiocin test | Identification for S. saprolyticus (Susceptible; zones >16 mm) *ONLY test where susceptible result is a positive |
| Rothia spp | NOT Staph but grows white colonies resemblings CoNS; VERY sticky colonies; Cat+/Coag- like CoNS |
| Aerococcus | Almost like a hybrid of Staph/Strep Cat- but is GPCC |
| 2 Step Coagulase Test | 1) Bound/Slide: On cell wall surface; turns F1>F1a (Stop here if positive) 2) Free/Tube: Extraceullar, reacts with plasma substances (Confirmatory is Step 1 was negative) |
| Strep family diseases | Pink eye, meningitis, endocarditis, necrotizing fascitis |
| Alpha strep | Strep pnuemo and S. viridans |
| Strep pneumo Identification | Alpha hemolytic, mucousy colonies; GS: LANCET PAIRS; Bile solubility/Desocycholate + (melts with drops); Optochin disk + (>14mm) |
| Bile solubility (Desoxycholate) | Drop on top of colonies and see if they bubble and dissolve (Positive: S. pneum / Negative: S. viridans) |
| Micrococcus | Typically normal flora; Small white, gray, or yellow (one species) colonies; GPC in tetrads; Cat wk(+); Modified oxidase/Microdase (+) (Blue color) |
| Micrococcus luteus | Gold colonies |
| Strep viridans | Usually normal nose/throat flora but pathogen in BALs; Buttery smell; Optochin and Bile Solubility/Desoxyxholate resistant (-) |
| Group A Strep (Strep pyogenes) | Causes strep throat, scarlet fever, rheumatic factor, and kidney damage; Large zones of beta hemolysis with small colonies |
| Group A Strep (Strep pyogenes) Identification | Cat(-), PYR(+), Hippurate(-), Bacitracin susceptible (ANY zone of clearance is +) |
| Group B Strep (Strep agalactiae) | Pathogen in urine, blood, CSF, wounds, genitals; Large colonies w/ small zones of beta hemolysis; Can colonies the vagina w/o symptoms; Newborns can get meningitis within 48 hours |
| Group B Strep (Strep agalactiae) Identification | Cat (-), CAMP (+), PYR (-), Hippurate (+) |
| Antibiotics that target the cell wall | B-lactams and Glycoproteins (Vancomycin) |
| Ideal drug for MRSA | Vancomycin |
| Antibiotics that target protein synthesis via the 30S subunit | Aminoglycosides and Tetracyclines |
| Kirby Bauer | Disk diffusion on Mueller Hinton agar, concentration at 0.5 McFarland |
| QC organisms for Kirby Bauer | E. coli, S. aureus, P. aeruginosa |
| Broth susceptibility | MIC = Minimum Inhibitory Concentration aka the lowest conc of drug that inhibits growth (MIB = Minimum bacteriostatic conc or 99% killing) |
| E-Test | MIC (Minimum Inhibitory concentration) on a strip impregnated with a gradient of drug concentrations |
| ESBL | Extended Beta Lactamase - Genes resistant to 3rd gen extended spectrum drugs (penicillin, cephalosporins) |
| Nitrocefin (Cefinase) Disk Test | Disk changes from yellow to red when B-lactam ring is hydrolyzed; detects resistance in Haemophilus, Neisseria, anaerobic GN rods but NOT in enteric GN rods |
| D-Test | Detection of inducible Clindamycin resistance; Clindamycin and Erythromycin disks are set on a plate; Inducible strains form a D shaped zone of inhibition |
| Detection of MRSA via susceptibility testing | Zone of <10mm on oxacillin disk on Mueller Hinton |
| Carbapenem Resistant Enterobacteriae (CRE) | Modified Hodge Test and chromogenic media; Relevant for Klebsiella pneumoniae, E. coli, Enterobacter; Includes drugs penicillin, cephalosporins, carbapenems |
| VRE | Vancomycin Resistant Enterococci (Gamma Strep) |
| Strep milleri (Strep anginosus) | Tiny alpha or beta colonies; Members of Strep Viridans group; +/- Lancefield group; Confused with A, C, F, G Strep |
| Nutrient deficient Strep | Beta strep; Abiotrophic species; May cause endocarditis; Requires Vit B6 (not in BAP); Must have Pyridoxal disk (Vit B6) to grow; May show on GS but not BAP |
| Enterococcus species | E. faecalis, E. faecium, E. gallinarium, E. cassaflava |
| Species of Enterococcus that share VRE genes | E. faecalis and E. faecium |
| Naturally Vancomycin resistant Enterococcus that do not share genes | E. gallinarium and E. cassaflava |
| Enterococcus identification | Gamma strep (but may be alpha or beta); Bile esculin (+/black); 6.5% NaCl (+/growth); PYR (+); Cat (+/-) |
| Group D Strep species | Strep bovis and Strep gallolyticus |
| Group D Strep is linked to... | Colon cancer |
| Group D Strep ID | Gamma strep; Bile esculin (+); 6.5% NaCl (-/no growth); PYR (-) |
| Hippurate | Detects ability to hydrolyze hippurate, creating a purple color; Indicator = Ninhydrin (oxidizing agent) |
| Positive for Hippurate (turns purple) | GBS, Campy jejuni, Gardnerella vaginitis |
| Negative for Hippurate | GAS |
| Oxidase | Pad that turns purple if bacteria colony smushed on it contains the enzyme oxidase |
| Oxidase is tested on all... | GNB |
| Positive for oxidase | Neisseria, Pseudomonas, Vibrio |
| Catalase | Produced in Staph; breaks down H2O2 and bubbles |
| Latex agglutination/Coagulase | Tests for S. aureus via presence of Protein A and Clumping Factor |
| Optochin disk | Copper compound; Strep pneumo susceptible (+); Strep viridans resistant (-) |
| Spot Indole | Card with Kovac's reagent, turns blue |
| Spot Indole is used to differentiate... | Species in Enterobacterales group |
| Positive for Spot Indole | E. coli |
| Negative for Spot Indole | Klebsiella pneumo |
| PYR | Smush colony on to disk and turns a pink color if organism has enzyme |
| Positive for PYR | GAS and Entercococcus |
| Negative for PYR | GBS |
| LAP | Disk turns pink |
| Positive for LAP | Enterococcus |
| Negative for LAP | GBS |
| Microdase/Modified Oxidase Test | Micrococcus spp contain enzyme that turns disk blue |
| Positive for Microdase/Modified Oxidase | Micrococcus |
| Negative for Microdase/Modified Oxidase | Staph |
| Butyrate Disk / Catscreen | Differentiates Moraxella (+) from Neisseria (-); Colony goes on disk which goes on card; Positive result = purple |
| Superoxide Test | 30% H2O2 bubbles; N. gonorrhoeae = SUPER positive, N. meningitis = Positive |
| H of HACEK | Haemophilus aphrophilus (Aggregator aphrophilus) |
| Haemophilus characteristics | GN coccobacilli or pleomorphic; Small gray colonies on Choc that resemble Neisseria; Grows at 35-37 C with 5-10% CO2 |
| Haemophilus pathology | Likes to stick and stay on lungs; Rides WBCs and inhibits phagocytosis |
| Haemophilus influenzae | ALWAYS a pathogen; Causes pink eye, pneumonia, septicemia; MAIN REASON WHY KIDS GET MENINGITIDIS; Found in eyes, CSF, blood, respiratory specimen |
| Haemophilus parainfluenzae | Normal flora |
| Haemophilus aphrophilus (Aggregator aphrophilus) | Normal flora but may cause cardiac infections from dental work; part of HACEK; Now confirmed to not be Haemophilus (is its own thing) |
| Haemophilus ducreyi | Tropical STD causing chancre; "School of fish" on GS |
| Satelliting of Haemophilus | Hazy growth around S. aureus on BAP since it's hemolytic and releases Factor X (hemin) while naturally producing Factor V (NAD+) |
| Factor requirements for H. influenzae | Factor X (Hemin) and Factor V (NAD+); NO hemolysis on horse blood |
| Factor requirements for H. parainfluenzae | Factor V (NAD+); NO hemolysis on horse blood |
| Factor requirements for H. haemolyticus | Factor X (Hemin) and Factor V (NAD+); BETA HEMOLYSIS on horse blood |
| Factor requirements for H. parahaemolyticus | Factor V (NAD+); BETA HEMOLYSIS on horse blood |
| Factor requirements for Haemophilus aphrophilus (Aggregator aphrophilus) | No factors needed and no beta hemolysis on horse blood |
| Factor requirements for H. ducreyi | Factor X (Hemin); NO hemolysis on horse blood |
| Strip testing for need for X or V factors | Deficient media with strips impregnated with factor; if needs both, will grow in an oval between both strips |
| Susceptibilities for Haemophilus | Cannot use regular Kirby-Bauer due to needing factors; Needs specialized plate = Haemophilus Test Media (HTM) |
| Neisseria characteristics | GNDC "KIDNEY BEAN" on GS; Small tan colonies; Cytochrome oxidase (+/blue); Coinfection with Chlamydia 80% of the time; Can travel into joints if untreated |
| Nonpathogenic Neisseria | Normal oral and skin flora; Yellow pigmented colonies on BAP/Choc/CNA ***Despite being GN, will NOT grow on MAC*** |
| MTM | Grows only pathogenic Neisseria (N. gonorrhoeae and N. meningitidis) |
| Can be used as QC for incubators due to fastidious nature | Neisseria meningitidis and gonorrhoeae (needs 35-37 C and 5-10% CO2) |
| Media pathogenic Neisseria grows on | MTM, Choc, BAP (slight) |
| CTA Sugars | Media will go pink to yellow with fermentation; Includes Glucose, Maltose, Lactose, Sucrose |
| CTA Sugars for N. meningitidis | Maltose and Glucose |
| CTA Sugars for N. gonorrhoeae (and N. cinerea) | Glucose |
| CTA Sugars for Moraxella | None |
| CTA Sugars for N. lactamia | Lactose, plus Maltose and Glucose |
| CTA Sugars for N. sicca | Sucrose, plus Maltose and Glucose |
| Moraxella catarrhalis | Usually commensal but may cause pneumonia and sinusitis; GNC, may be diplococcal; Gray colonies on BAP and Choc but NOT MAC; NO GROWTH ON MTM; Colonies are hard and may "move" |
| Moraxella catarrhalis biochemicals | Cytochrome oxidase (+/blue), Cat (+), CTA sugars (-), CAT screen (+) |
| Neisseria biochemicals | Cytochrome oxidase (+/blue), Cat (+), CTA sugars (+), CAT screen (-) |
| Bacillus anthracis | BIOTERRORISM AGENT; Aerobic spore forming GPB; Nonmotile and nonhemolytic (unlike other Bacilli); MEDUSA HEAD COLONIES; Can grow spores (nonstaining beads on GS); Very long chains on GS ("bamboo shoots") |
| Bacillus implicated in food poisoning, lasts <24 hours but hits like a truck; Fried rice food poisoning | Bacillus cereus |
| Nonbioterroristic Bacillus | Usually nonpathogenic; Grows quickly; Motile and Beta or Gamma hemolytic; Cat (+); Oxidase (+) |
| Corynebacterium | Diphtheroids; Pleomorphic GPB (club shaped, palisading); White, gray, yellow, occasionally black colonies on BAP, CNA, Choc; Usually nonpathogenic (3 pathogenic species); Nonmotile |
| Corynebacterium diphtheriae | Gray pseudomembrane in throat causes suffocation; Grows white colonies on BAP and Choc; Special media (Tinsdale, Loeffler's, Cysteine Tellurite); UREA (-) |
| Cysteine Tellurite | Special media for Corynebacterium diphtheriae; Brown to black colonies |
| Loeffler's media | Special media for Corynebacterium diphtheriae; Enhances growth for metachromatic granules to show red-purple "beaded areas" on Methylene Blue Stain |
| Tinsdale media | Special media for Corynebacterium diphtheriae; Gray to black colonies |
| Elek Test | Antitoxin strip with 3 other strips perpendicular (Known toxinogenic C. dipht, Patient, Known nontoxinogenic C. dipht); If C. dipht toxin is present, precipitate lines will form |
| Corynebacterium jekeium | Environmental, on objects; may become nosocomial infection in immunocompromised patients; UREA (-); Antibiotic resistant except for Vancomycin |
| Corynebacterium urealyticum | Found in urine of males and in female UTIs; Associated with kidney stones; Multidrug resistant but Vancomycin sensitive; UREA (+) |
| Only urea (+) Corynebacterium | Corynebacterium urealyticum |
| Listeria monocytogenes | Small GPB; Can cause food poisoning; Growth on BAP resembles GBS; Umbrella motility in semisolid agar and tumbling motility on wet prep at RT (NOT 37C) |
| Listeria monocytogenes biochemicals | Hippurate (+), CAMP (-), CAT (+), Bile esculin (+) [WEIRD SINCE IT'S NOT ENTEROCOCCUS], Motile |
| Erysipelothrix | Skin ulcers associated with hog farmers, fishermen, rose gardening, butchers, vets; Small, nonmotile GPB; Hold BAP for 7 days (takes 48 hrs to grow) |
| Lactobacillus | Commensal vaginal long GPB that regulates pH; Cat (+); Nonmotile; Alpha hemolytic |
| Arcanobacterium | GPB causing pharyngitis; Confused for GAS due to also growing small beta hemolytic colonies and being Cat (-) [DIFFERENCE: PYR (-) and Lancefield (-) |
| Actinomycetes order | Branching GPB; Smells moldy; Species: 1) Actinomyces 2) Nocardia 3) Streptomyces |
| Actinomyces spp pathology | Chronic yellow sulfur granulomatous lesions ("lumpy jaw"); Found with poor dental care, IUDs, wounds, Pelvic Inflammatory Disease |
| Actinomyces spp colony morphology | MOLAR TOOTH COLONIES |
| Is Actinomyces spp aerobic, anaerobic...? | Aerotolerant anaerobe |
| Actinomyces spp staining | Branching GPB in V and Y formations on GS; Modified Acid Fast stain negative (blue) |
| Actinomyces israelii | Most frequently isolated in serious anaerobic infections (ONLY Actinomyces that is a strict anaerobe) |
| Nocardia | Opportunistic, found in decaying plant matter, gardening; Branching beaded GPR; Modified acid stain positive (pink) |
| Nocardia biochemicals | Modified acid stain positive (pink), Urea (+), Gelatin (+) |
| Modified Partial Acid Stain components | Carbol fuscin, acid alcohol and Methylene Blue (counterstain) |
| Modified Partial Acid Stain positive stain | Pink or red, may show beading ("partial" acid fastness) |
| Modified Partial Acid Stain negative stain | Blue (background) |
| Streptomyces | Nonpathogenic Actinomycetes; Branching GPB; Used to make antibiotics; Modified acid stain negative |
| Phenyl Ethyl Alcohol (PEA) agar | Selects for GPC or anaerobic GNB |
| Broths with Thioglycolate or Cystine | Anaerobes |
| Lowenstein-Jensen agar | Mycobacterium spp |
| Middlebrook 7H10 agar | Mycobacterium spp |
| Petragnani agar | Mycobacterium spp |
| Bacteroides Bile Esculin agar (BBE) | Selects for B. fragilis group (black colonies) |
| Kanamycin Vancomycin Laked Bood agar (KVLB) | Bacteroides (enhances pigment) and Prevotella |
| CCFA agar | C. difficile |
| Anaerobic PEA agar | Prevents swarming and inihibits Enterobacteriaceae |
| CDC Anerobic Blood agar | Grows anaerobes; Rich with Hemin, Cystine, and Vit K |
| Bordet-Gengou agar | B. pertussis |
| Buffered Charcoal Yeast Extract agar (BYCE) | Legionella spp. |
| Cystine Glucose agar | F. tularensis |
| Fletcher's medium | Leptospira |
| Skirrow agar | H. pylori |
| TCBS agar | Vibrio sp |
| Vaginalis Agar (V-Agar) (human blood) | Gardnerella vaginalis |
| CIN agar | Yersinia and Aeromonas |
| Positive result for Phenylalanine or Tryptophan deaminase | Green surface after 10% FeCl3 |
| Specimens which should never be refrigerated | CSF or Gonorrhoeae/Chlamydia |
| Collect before or after antibiotic therapy? | Before |
| Best time to collect blood cultures | Just before fever spike |
| How many blood cultures to draw? | 2 to 3 every 24 hours |
| Volume of blood needed in blood culture bottles | To make it a 1:10 dilution (10 mL adults, 5 mL pediatrics) |
| Darkfield microscopy | Ideal for spirochetes; uses reflected light |
| Conditions Campy needs | 42 C with 5-10% CO2 and minimal oxygen |
| Temperature to incubate Yersinia at | 20-30 C |
| Volumes at which loops are calibrated at | 0.01 or 0.001 mL |
| Multiply colonies found by (due to dilution by loop) | 100 or 1000 |
| Read and report plates after | 18 to 24 hours |
| Acid fast (Ziehl-Nielson and Kinyoun) | Carbol fushin (pink) primary stain with Methyl Blue counterstain; Positive (pink) for Mycobacteria |
| Auramine or Rhodamine Stain | Auramine or Rhodamine fluorescent primary stain with Potassium Permanganate counterstain; Positive (fluorescent orange) for Mycobacteria |
| Staph aureus diseases | Scalded skin syndrome, Toxic shock syndrome, Paronychia, Boils and blisters, Impetigo, Food poisoning |
| Staph aureus resistance | Usually resistant to pencillins due to plasmid mediated B-lactamase |
| Staph aureus sensitivities | PRP (Penicillinase resistant penicillin) such as methicillin and oxacillin. If resistant, Vancomycin is the drug of choice. |
| Staph ludugnensis | Only CoNS that is PYR (+) |
| CoNS diseases | Endocarditis; opportunistic in prosthetic devices |
| Strep pyogenes sensitivities | Extremely susceptible to pencillin |
| Strep pneumo complications | Rusty sputum (primary lobular pneumonia), meningingitis, otitis media, conjunctivitis, bacteremia |
| Strep viridans complications | Subacute bacteria endocarditis |
| Strep pyogenes virulence factors | Protein M (sore throat and muscles) and Streptolysin O (heart and kidneys) |
| Waterhouse-Friderichsen Syndrome | Caused by N. meningitis; scattered petechiae and bleeding into adrenal glands causing septic shock; rapidly fatal if not treated with steroids |
| Chemistries/Diff for bacterial meningitis | High protein, low glucose, high neutrophils |
| Gardnerella vaginalis | Tiny Gram variable rods; Clue cells; 10% KOH drop creates "fishy" odor; Tiny colonies on BAP and Choc after 48 hours |
| Gardnerella vaginalis biochemicals | Cat and oxidase (-); Hippurate and starch (+) |
| Listeria monocytogenes diseases | Sepsis in immunocompromised; In utero meningitis or sepsis if mom is exposed via lunch meat, unwashed vegetables, or dairy |
| Erysipelothrix biochemicals | Cat (-); H2S (+) in TSI |
| Bacillus colonies | Ground glass, large beta hemolytic (unless a bioterrorism agent) |
Created by:
rachelkayw