GNC flashcards

neisseria gen characteristics

* aerobic, capno, dpc
* ox pos, cat pos
* except for n. elongate, bacilliformis, weaver

where is neisseria normal flora? what are the exceptions?

* upper resp and urogenital tracts
* gonorrhoeae is always pathogen
* meningitidis can be in URT but is invasive pathogen

n. gonorrhoeae

* humans only natural host (asymptomatic carriers)
* transmitted via sexual contact
* nationally reportable disease
* ages 20-24

virulence factors of n. gonorhoeae

* receptors for human transferrin
* pili
* IgA protease
* major outer membrane porin proteins
* capsule
* lipooligosaccharides

por A/B - n. gonorhhoeae

* channel for nutrients to enter and waste products to exit the cell
* effective against inflammatory response and complement killing

protein II (Opa) - n. gonorrhoeae

facilitate adherence to phagocytic and epi cells

protein III - n. gonorrhoeae

block host serum bactericidal action

gonorrhea

* acute pyogenic infection of urogenital tract, pharynx, conjunctiva
* less likely: disseminated infections, anal canal
* incubation period: 2-7 days

gonorrhea in males

* 90% symptomatic
* dysuria, urethral discharge
* complications: epididymitis, prostatitis

gonorrhea in females

* 50% symptomatic
* infects endocervix
* dysuria, cervical discharge, lower abd pain
* complications: PID (sterility), ectopic pregnancy, perihepatitis (fitz-hugh-curtis)

blood borne dissemination - n. gonorrhoeae

* fever, rash, gonococcal arthritis
* SPS inhibits growth so use gelatin for blood cx

ophthalmia neonatorum - n. gonorrhoeae

* occurs during vaginal delivery so we give erythromycin drops at birth
* blindness if not treated

extragenital infections of n. gonorrhoeae

* pharyngitis
* anorectal infections (from proximity of genital infection in women)
* ocular infections in adults
* asymptomatic/nonspecific symptoms

specimens for n. gonorrhoeae

* urethra (males): insert swab, slowly rotate (dacron/rayon)
* endocervix
* rectal
* oral/pharyngeal
* eye
* blood/joint fluids

specimen collection for n. gonorrhoeae

* dacron/rayon (cotton and calcium alginate are toxic)
* plate immediately in transport media (jembec, gonopak, amies, transgrow)
* swabs placed in amies with charcoal and plated in 6 hrs

media - n. gonorrhoeae

* CHOC with inhibitors for GP/GN/yeasts
* capno incubator, generating pouch
* TM or MTM (vanc, colistin, nystatin, trimethoprim)

morphology of n. gonorrhoeae

* GN kidney bean dpc
* MTM: small, gray tan, translucent, raised
* read at 3 days

immunologic assays - n. gonorrhoeae

* coagglutination: monoclonal Abs bound to dead s. aureus
* agglutination = pos
* maldi tof
* fluorescent Ab testing: monoclonal Abs bound to Por protein

nucleic acid assays - n. gonorrhoeae

* rapid, preferred for detection
* inc sensitivity, specificity
* first morning urine
* no AST b/c no organism recovery

antimicrobial resistance - n. gonorrhoeae

* PPNG (penicillinase producing)
* altered PBP
* resistant to tetra, spectinomycin, fluoros
* treat with cephalosporins

n. meningitidis

* found only in humans on mucosal surfaces
* can be commensal or invasive pathogen
* infants and adolescents

transmission of n. meningitidis

* resp droplets: close contact, crowded living conditions
* incubation period 1-10 days

meningitis - n. meningitidis

* frontal headache, stiff neck, confusion, photophobia
* 10-15% fatality

meningococcemia - n. meningitidis

* purpura, petechial rash
* tachy, hypotension

fulminant disease - n. meningitidis

* spreads rapidly = DIC, septic shock
* hemorrhage in adrenal glands (waterhouse friderichsen syndrome)
* death in 12-48 hrs

specimen for n. meningitidis

* CSF, blood, NP swabs/aspirates
* conc CSF
* inhibited by SPS so use different blood cx method

morph of n. meningitidis

* colonies larger then n. gonorrhoeae at 18hrs
* smooth, moist, glistening, tan
* grows on CHOC, BAP, selective

treatment for n. meningitidis

* penicillin
* prophylaxis with cipro, ceftriaxone, rifampin

meningococcal vaccine

* 18-23 yrs old
* military, asplenic pts, lab scientists

moraxella catarrhalis

* normal flora of resp tract: opportunistic pathogen only found in humans
* URTIs: healthy ppl
* LRTIs: COPD pts
* 3rd common cause of ear/sinus infections in kids
* rarely: endocarditis, meningitis, bacterial tracheitis

specimen for m. catarrhalis

* middle ear effusion
* nasopharynx
* sinus, sputum, bronchial aspirates

morph of m. catarrhalis

hockey puck colony, older = wagon wheel

m. catarrhalis biochemicals

* ox pos
* butyrate esterase pos
* DNase pos

treatment of m. catarrhalis

* most produce beta lactamase (resistant to amp/amox)
* amoxicillin/clavulanic acid, cephalosporins, azithro, quinonlines, STX

nonpathogenic neisseria

* normal flora if in resp specimens
* rarely cause disease (opportunistic)
* if from sterile site: need to ID

oxidase test

* tests for cytochrome oxidase via tetramethyl-p-phenylene-diamine-dihydrochloride
* purple color = pos

superoxol test

* catalase with 30% H2O2 (hazardous)
* n. gonorrhoeae is pos
* all other neisseria are neg

what will n. gonorrhoeae grow on?

CHOC, TM

what will n. meningitidis grow on?

BAP V, CHOC, TM

what will n. lactamica grow on?

BAP, CHOC, TM, NA

what will nonpathogenic neisseria and m. catarrhalis grow on?

BAP, CHOC, NA

CTA - cystine trypticase soy agar

* cystine supports fastidious growth
* semisolid contains 1% of carb
* pattern of utilization speciates neisseria
* phenol red
* read 24-72 hrs

CTA/enzyme substrate results of n. gonorrhoeae

* glucose pos
* hydroxypropylaminopeptidase = pink/red

CTA/enzyme substrate results of n. meningitidis

* glucose, maltose pos
* gamma glutamylaminopeptidase = yellow

CTA/enzyme substrate results of n. lactamica

* glucose, maltose, lactose pos
* beta galactosidase = blue

CTA results of n. sicca

glucose, maltose, sucrose pos

CTA/enzyme substrate results of m. catarrhalis

* all carbs neg
* no enzyme = clear

enzyme substrate test

* rapid ID of pathogenic neisseria/m. cat
* tests for enzyme production

butyrate esterase test

* enzyme reacts with disk impregnated with indoxyl butyrate substrate
* hydrolysis releases indoxyl + O2 = indigo color (m. cat)
* all neisseria neg = no rxn

CLSI - n. gonorrhoeae

* presumptive:
* GN dpc
* ox pos
* cat strong pos (superoxol pos)
* additional test: neg gamma and beta enzymes
* notes: must grow on selective media or no growth on mueller hinton/tryptic soy agar

CLSI - n. meningitidis

* presumptive:
* GN dpc
* ox pos
* glistening nonhemolytic growth on BAP
* additional tests: gamma enzyme pos
* notes: work in BSC, highly infectious

CLSI - lactamica

* presumptive:
* GN dpc
* ox pos
* grayish nonhemolytic on BAP
* additional tests: beta enzyme pos

CLSI - m. catarrhalis

* presumptive:
* GN dpc
* ox pos, cat pos
* entire nonhemolytic colony moves intact when pushed
* additional tests: butyrate pos OR indoxyl acetate pos