Ap Cp Pathology Boards Bacteriology

Front 1

0.5 McFarland Standard = ?

Back 1

Barium sulfate standard that equals the turbidity of 10^8 bacteria

Front 2

Agar Disk Diffusion/Kirby Bauer Method

Back 2

Mueller Hinton agar

150 mm plate diameter

4 mm in depth

Specifically calcium and magnesium balanced

6mm paper disk with single antibiotic

Front 3

E Test

Back 3

Calibrated plastic strips impregnanted with antibiotic [ ] gradient

MIC is where ellipse ends

Front 4

Broth dilution ?

Back 4

0.5 McFarland standard - further diluted to 5 x 10^5 organisms/mL

-Suspension inoculated into tubes/trays containing growth medium and known 2 fold dilutions of antibiotics

-Must have 4 or more dilutions to be true MIC

Front 5

Disk test for beta lactamase detection?

Back 5

-Add bacteria to filter paper impregnanted with Nitrocefin (chromogenic cephalosporin)

-Incubate at RT 30 sec to 60 min (depends on bacteria)

-Positive result is change from yellow to red

-Beta lactamase enzyme breaks down beta lactam ring to form hydrolyzed red end product

-Detects resistance to Amp/Pen/Ceph

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MRSA resistance

Back 6

-Resistance by penicillin binding proteins (PBP) via mecA gene

-Test oxacillin in lab (more stable) - if resistant, all cephalosporins are reported as resistant

-Newer method uses cefoxitin for greater sensitivity

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Clindamycin Induction (D Test)

Back 7

-To determine if S. aureus/MRSA is susceptible to Clindamycin

-S. aureus/MRSA resistant to erythromycin and susceptible to clinda have to be tested

-Zone around clinda disk will be blunted to form D if clinda can be induced by erythro to be resistant

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Enterococcus resistance + synergy

Back 8

Naturally resistant to:

Cephalosporins

Clindamycin

TMP/SXT

Synergy:

Ampicillin + Gentamycin

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Vancomycin resistant enterococcus (VRE)

Back 9

Acquired resistance to vancomycin:

-plasmid mediated vanA - E. faecium

-plasmid mediated vanB - E. faecalis

Drugs of choice:

Linezolid & Synercid

Front 10

Extended spectrum beta lactamase (ESBL) production

Back 10

E. coli, Klebsiella, and Proteus mirabilis ONLY have CLSI methods for detection

-Via Tem 1 beta lactamase plasmid

-Report all cephalosporins and penicillins as resistant

-Drug of choice Imipenem, Pip/Tazo - blocks beta lactamase function

-Clavulinic acid = beta lactamase blocker

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Klebsiella pneumonia carbapenemase

Back 11

-Carbapenemase producing

-Hyper beta lactamase producer plus resistance to carbapenems (Imepenem)

-Most sensitive screen for KPC is Ertapenem = increased MIC

-Lawn of E. coli, streaks of test GNR

-A,B,E positive

Front 12

Streptococcus pneumonia and resistance to penicillin

Back 12

1) Oxacillin KB disk test

2) Confirmation of resistance by penicillin MIC testing with E test or broth dilution

Sensitive (<0.06 mcg/mL for CSF infections & <2 mcg/mL for respiratory/blood infections)

Resistant (>2 mcg/mL for CSF infections & >8 mcg/mL for respiratory/blood infections)

-If resistant use cefotaxime, vancomycin or a quinolone

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Back 13

Front 14

Chlamydia culture

Back 14

-McCoy cells with iodine or DFA staining vacuole

-Elementary bodies = small extracellular bodies

Front 15

Clostridium difficile

Back 15

-NAP1 strain = hyper-virulent with increased spore toxin production

-Toxin A (enterotoxin)

-Toxin B (cytotoxin)

PCR test of choice

Front 16

Phenylethyl alcohol

Back 16

Selects for gram positive cocci

Front 17

MacConkey agar

Back 17

Selects for gram negative bacilli and differentiates lactose fermenters

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Staphylococcus aureus

Back 18

1) Virulence Factors: Protein A - capsular polysarccharides, enzymes (coagulase), toxins and hemolysins

2) Diseases: Toxic shock syndrome (TSST-1), scalded skin syndrome (Exfoliatin, SSS), soft tissue skin infections (Panton Valentine leucocidin - PVL), food poisoning (enterotoxins), bacteremia, and endocarditis

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Back 19

S. epidermidis - Novobiocin sensitive

-Pathogenesis from cell adhesion factors forming biofilms on biologics & plastic

S. saprophyticus - Novobiocin resistant

-UTIs in child-bearing age female

Front 20

Micrococcus:

gram positive cocci in tetrads

Back 20

Catalase Negative

Bright yellow pigment

Bacitracin Susceptible

Microdase test + (modified oxidase reaction)

Does not ferment glucose (staph does)

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Back 21

S. pyogenes:

Beta-hemolytic

Group A strep

PYR +

Bacitracin & Penicillin susceptible

SXT resistant

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Streptococcus pyogenes

Back 22

Virulence Factors:

M protein - resistance to phagocytosis

Capsule - hyaluronic acid - resistant to complement-dependent killing

Streptolysin O (oxygen labile) & Streptolysin S (oxygen stable)

Streptococcal pyrogenic exotoxins

Front 23

Streptococcus pyogenes

Back 23

Diseases:

Pharyngitis

Impetigo

Erysipelas

Cellulitis

Puerperal sepsis

Toxic shock

Sequelae:

Rhematic fever & glomerulonephritis

Front 24

S. agalactiae

-S. aureus strain with camp factor perpendicular to group B strep = flare of hemolysis

Back 24

Group B strep = S. agalactiae

beta hemolytic

Catalase negative

CAMP test +

Hippurate + (purple)

Penicillin, Vanco S

Front 25

Enterococcus

Back 25

Enterococcus:

Gamma hemolytic streptococcus

Bile esculin +

6.5% salt +

PYR + (pink)

E. faecium = arabinose fermentation +

E. faecalis = arabinose -

Natural resistant to cephalosporins

Tx with Amp/Vanc

Front 26

Streptococcus Group D, not enterococcus

Back 26

S. bovis:

Gamma hemolytic

Bile esculin +

6.5% salt -

PYR -

-Associated with bowel carcinoma

Always susceptible to penicillin

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Alpha Hemolytic Streptococcus

-Optochin = ethyl hydrocupreine hydrochloride

Back 27

S. pneumonia:

Lancet-shaped

Optochin sensitive

Bile soluble

Acquired R to Penicillin by PBP

Quellung reaction to type

Viridans strep:

S. mutans, S. salivarius, S. sanguis, S. mitis

Optochin resistant

Bile esculin -

Not bile soluble

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Nutritionally variant Strep

-Vit B6 provided by S. aureus

Back 28

Vitamin B6 (pyridoxal) dependent

-Needs S. aureus streak to grow "satellite" or media supplemented with B6

Speciated:

1) Abiotrophia

2) Granulacatilla

Can cause endocarditis, more resistant to antibiotics

Front 29

Gram Negative Cocci

Neisseria

Moraxella catarrhalis

Back 29

Positive - turns from pink to yellow

Front 30

Corynebacterium diphtheriae

Back 30

C. diphtheriae:

-phage mediated toxin

-Cysteine tullerite agar - black colonies with brown halos

-Grow on egg containing Loeffler slant then stain with methylene blue = metachromatic granules

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C. jeikeium:

1) Pts with plastic catheters and indwelling devices

2) R to most antibiotics

3) Tx with Vancomycin & tetracycline

Back 31

C. urealyticum:

1) Rapidly urease positive diphtheroid found in urine cultures

2) Alkaline-encrusted cystitis

Front 32

Bacillus species

Back 32

Gram + bacilli, boxcar shaped, spore-forming

B. anthracis:

-medusa head colonies on BAP

-non-hemolytic, non-motile, Penicillin S

B. cereus:

-cereulide = emetic toxin

-beta-hemolytic, motile

Front 33

Listeria monocytogenes

Back 33

Small gram positive rod

Catalase +

Beta-hemolytic colony

Intracellular pathogen

Tumbling motility

Cold loving - 4 degrees Celsius

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Erysipelothrix rhusiopathiae

Back 34

Gram + rod

Catalase -

Alpha hemolytic colony

**Only gram + rod that produces H2S (TSI)

**Strongly associated with endocarditis in drug addicts

Front 35

Triple Sugar Iron Agar

Back 35

Detect fermentation of glucose, lactose, and/or sucrose and the production of hydrogen sulfide

Pink = no fermentation

Glucose at bottom

Lactose/Sucrose at top

Front 36

Proteus:

non-lactose fermentation

P. vulgaris - indole +

P. mirabilis - indole -

Back 36

Serratia marcescens:

red pigmentation

infection in immune suppressed

Front 37

Salmonella

diarrhea, polys in stool

Selective media - Hektoen and SS

Does not ferment lactose

Produces H2S

Identification based on Kaufman White type scheme

O - somatic antigen - cell wall

H - flagellar antigens - 2 phases, h1 & h2

Back 37

S. typhi:

Vi capsular antigen and D somatic antigen

Moustache of H2S in the TSI tube

Carrier state in gallbladder

Front 38

Shigella

Back 38

gram negative bacilli

diarrhea, blood in stool

non motile

no H2S production

non lactose fermenter

4 species:

S. boydii - group C

S. dysenteriae - group A

S. flexneri - group B

S. sonnei - group D

Front 39

Yersinia enterocolitica

Back 39

diarrhea

septicemia in iron overload syndromes

mesenteric adenitis - mimics appendicitis

grows well at 4 degrees C (like Listeria)

CIN agar (cefsulodin-irgasan-novobiocin)

Front 40

Yersinia pestis

safety pin - bipolar staining

Back 40

obligate flea-rodent-flea life cycle

Flea bite leads to bubonic form with painful buboes

pneumonic form - bacteremic spread or patient to patient

southwestern part of US

grows on BAP, catalase +, oxidase -

gram negative rod

Front 41

Vibrio cholerae

-glucose fermenter

-oxidase +

Back 41

1)gram negative bacillus - comma-shaped

2) toxin - receptor on endothelial cell - activates adenylate cyclase - increases cAMP - hypersecretion of salt & water

3) Halophilic, 1% salt enhances growth

4) TCBS = thio citrate bile sucrose - turns yellow due to sucrose fermentation

5) 01 most virulent - classic & El Tor - toxin +

Front 42

Other Vibrio species

-glucose fermenters, oxidase +

Back 42

V. parahemolyticus:

1) sucrose neg - green on TCBS

2) diarrhea from ingestion of raw fish & shellfish

V. vulnificus:

1) painful lower limb bullous lesions

2) septicemia in pts with pre-existing liver disease

3) lactose + - green or yellow on TCBS

Front 43

Glucose non-fermenters

Oxidase negative

Back 43

Acinetobacter:

1) Nosocomial pathogen

2) Gram neg coccobacillus - big diplococci

3) A. baumannii - glucose oxidizer

4) A. lwoffi - glucose non-oxidizer

Stenotrophomonas:

1) Rapid maltose oxidizer

2) Naturally resistant to Imipenem

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Pseudomonas aeruginosa

Back 44

1) Fluorescent pigment & blue-green pigment (pyocyanin)

2) Grape-like odor

3) Grows at 42 degrees celsius (P. fluorescens/putida don't)

4) Major pathogen in CF along with Burkholderia cepacia

Front 45

Haemophilus

Back 45

H. influenza:

1) Requires X (hemin) and V (NAD)

2) 15-20% R to Amp by beta lactamase production

H. parainfluenza:

1) Requires V only

H. aphrophilus:

1) Doesn't require X or V

H. ducreyi:

1) Requires X

Front 46

HACEK Group

Back 46

Haemophilus acrophilus = oxidase -, catalase -

Actinobacillus actinomycetom-comitans = oxidase -, catalase +

Cardiobacterium hominis = oxidase +

Eikinella corrodens = oxidase +, pits on BAP

Kingella kingii = oxidase +, hemolytic on BAP

Front 47

Bordetella pertussis

Back 47

1) Gram negative coccobacillus

2) Direct detection by fluorescent antibody

3) Regan Lowe charcoal agar - bluish colonies

4) Cough caused by toxin adhering to bronchial epithelial cells

Front 48

Pasturella multocida

Back 48

1) Small gram negative coccobacilli

2) Cat & dog bites, normal flora in animal's mouth

3) Grows on blood, not MacConkey agar

4) Sensitive to penicillin

5) Oxidase +

Front 49

Brucella

Back 49

1) Small gram negative coccobacilli

2) Fever of unknown origin, joint pain

3) Species related to animal spp exposure:

B. abortus = raw cow milk

B. melitensis = raw goat milk, feta cheese

B. suis = pigs

B. canis = dogs

Front 50

Campylobacter

Back 50

Small curved bacilli - like sea gull wings

C. jejuni:

undercooked poultry ingestion

requires selective media containing antibiotics = Skirrow's blood agar

significant % Guillain barre syndrome as sequelae

-Grows as 37 & 42 degrees celsius

C. fetus - blood culture pathogen in immune suppressed host

-Grows at 37 & 25 degrees celsius, not at 42

Front 51

Capnocytophaga

Back 51

1) Fusiform shaped gram negative rods - very pleomorphic

2) Oxidase -

3) Catalase -

4) Gliding motility, fingerlike projections from colonies

C. canimorsus - dog bites & bacteremia

Other species in the human mouth cause bacteremia in cancer pts on chemotherapy

Front 52

Francisella tularensis

Back 52

1) Small gram negative coccobacilli

2) Reservoir - rabbits, rodents

3) Culture media must have cysteine (like legionella)

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Legionella

Back 53

1) Requires cysteine for growth (like francisella tularensis)

2) Media of choice BCYE (buffered charcoal yeast extract)

3) Does not gram stain in direct specimens, use silver impregnation stains in tissue

4) L. pneumophila - urine antigen test

5) Tx: erythromycin

Front 54

Bacteria without cells walls:

1) Mycoplasma

2) Ureaplasma

-Have cell membrane only

-Transport media must contain sterols

Back 54

M. hominis - fried egg colony; causes vaginitis, cervicitis, postpartum sepsis, neonatal infections, PPROM

U. urealyticum - rapid urea hydrolysis in broth; causes upper genital tract infections, SAB, neonatal infections

Front 55

Ehrlichia

Back 55

1) Intracellular pathogen, tick-borne

2) Fever, leukopenia, thrombocytopenia, high serum aminotransferases, no rash (unlike RMSF)

3) E. chaffeensis - human monocytes

4) Ehrlichia spp. - human granulocytes

5) Found in midwest

6) PCR & serology for diagnosis

Front 56

Spirochetes

Back 56

1) Borrelia burgdorferi - Lyme's disease

-Tick vector (Ixodes)

2) Borrelia recurrentis - relapsing fever

-Human body louse

3) Leptospira interrogans - Leptospirosis

-Rats & other animals; water association

4) Treponema pallidum - syphilis

-RPR, VDRL

Can't culture any of these, need to use serology or molecular

Front 57

Anaerobic Bacteria

Back 57

1) Bacteriodes fragilis group

2) Fusobacterium

3) Clostridium species

4) Actinomyces

5) Propionibacterium

Front 58

Bacteriodes fragilis group

Back 58

1) Grow in presence of bile

2) Esculin +

3) Pleomorphic gram negative bacilli

4) B. fragilis, B. ovatus, B. thetaiotamicron (indole positive), B. uniformis, B. vulgatus

Front 59

Fusobacterium

Back 59

1) Fusiform gram negative bacilli

2) Spindle-shaped with POINTED ends

3) Associated with mouth & respiratory tract abscess

4) F. necrophorum is the type of species

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Clostridium

Back 60

1) Gram positive bacilli (box car shaped)

2) Spore forming

3) C. perfringens:

-double zone of beta hemolysis

-reverse camp test +

4) C. botulinum:

-food borne toxin ingestion in adults

-spore ingestion in small children

-causes flaccid paralysis

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Clostridium continued...

Back 61

5) C. tetani:

-looks like tennis racket (spore at end)

-penetrating skin injury

6) C. septicum:

-organism in blood associated with cancer

7) C. difficile:

-enterotoxin A; cytotoxin B

-NAP1 strain bad

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Actinomyces

Back 62

1) Branching, gram positive bacilli

2) Capable of forming sulfur granules in tissue

3) Found on normal tonsils

4) A. israelii: associated with oral, thoracic, and abdominal infections

-IUD infections

-Bread crumb colonies in broth, molar tooth colon on agar plates

Front 63

Propionibacterium acnes

Back 63

1) Pleomorphic gram positive rod

2) Can be pathogen in cerebral shunt infections

3) Can cause shunt nephritis