Aerobic Gram-negative Cocci: Neisseria & Moraxella catarrhalis

Neisseria traits

-GNC in pairs

-inhabit mucous membranes

-nonmotile, non-spore

-capnophilic (likes CO2!), grows best in moist conditions 35-37C

-oxidase =pos

-catalase = pos

N. gonorrhoeae is always ___ and humans are ___.

clinically significant; only host

N. gonorrhoeae infn

-how does it present in males vs females?

other forms?

males: symptomatic urethritis

-painful urination, discharge from urethra, swollen testicles

females: cervicitis (most asympt)

-abdominal pain, but mostly unaware → can cause purulent discharge

rectal & throat/pharygeal gonorrhoea → most asympt

N. gonorrhoeae clinical complications

ascending infns (10-20% females)

-acute PID (pelvic inflam disease) → affect child birth

-Salpingitis (fallopian tubes)

-Fitz-Hugh-Curtis syndrome - perihepatitis

epidymitis, prostatitis in males

bacteremia, arthritis (joint fluid **remember Susan!), endocarditis, meningitis

opthalmia neonatorum (crusty baby eyes)

N. gonorrhoeae virulence factors

pili - adhere to host cells, impede phagocytosis

protein II - helps invasion

IgA protease - deactivates IgA at mucosal surfaces

LPS - stimulates inflam response → lysis of PMns and epi’s

plasmids: Abx-R

N. gonorrhoeae specimen collection

-dacron or rayon swab (calcium alginate and cotton swabs may inhibit)

-avoid oil-based lubricants, cold water for vaginal specula

-max recovery via inoculating media at bed side

if not possible → transport systems: JEMBEC, Gono-pak, Transgrow

acceptable specimens for N. gonorrhoeae

genital

• male - urethra

• adult female - endocervix

• prepubertal female - vagina or urethra

orophargyngeal

anal

disseminated: blood, skin lesions, joint fluid (Susan!)

transgrow bottle

MTM medium, CO2, inoc at RT, inoc in upright position

selective media for N. gonorrhoeae

• Thayer Martin

• Modified TM

• Martin Lewis

• New York City

what is the role of each Abx?

TM: vancomycin, colistin, nystatin

MTM: same ^ + trimethoprim sulfa

Martin Lewis: same as MTM, except anisomycin instead of nystatin

NYC: vancomycin, colistin, amphotericin B, trimethoprim sulfa + etc → supports genital mycoplasma & ureaplasma

vancomycin → inhibits G+

colistin → inhibits GNR

nystatin, anisomycin, amph B: antifungals (yeast in genital)

trimethoprim sulfa: inhibits swarming in Proteus (can still grow)

Why do candle jars work for N. gonorrhoeae?

burns O2 in jar → makes capnophilic conditions

N. gonorrhoeae morph

small, translucent, gray, convex, smooth or irregular margin

may be mucoid, sticky

5 things for presumptive ID of N. gonorrhoeae

1. G- intracellular cocci in pairs

2. genital site (adults only)

3. grows on GC selective agar

4. oxidase +

5. superoxol +

oxidase test

tests for cytochrome oxidase → breaks down tetra(or di)methyl-p-phenylenediamine dihydrocholride → indophenol blue

reagent = tetramethyl-p-phenylenediamine dihydrochloride (Kovacs reagent)

on filter paper in petri dish, 1 drop of Kovacs reagent → wooden stick of colony (better if from non-choc media)

pos = dark purple

neg = no color change

superoxol test

used for N. gonorrhoeae ID

same as catalase

reagent = 30% hydrogen peroxide

pos = vigorous rapid bubbles

neg = weak or no bubbles

confirming N. gonorrhoeae ID (once growth on GC selective media)

carbohydrate utilization, immunologic (coagglutination & direct fluorescent antibody test), enzymatic, multitest ID systems (Vitek - uses sugar-utilization & enzyme rxns)

carbohydrate utilization tests for N. gonorrhoeae

only uses glucose

pos = yellow from phenol red pH indicator

neg = red

N. gonorrhoeae recovered from children must be confirmed by at least 2 methods of different principles →

nucleic acid hybridization, immunological, carbohydrate utilization

for legal cases → only culture acceptable, no PCR, too risky for a false +

Neisseria meningitidis epidemiology

humans only host

transmitted by respiratory droplets, colonizes upper respiratory mucosa

asymptomatic carriage common: 8-20% general popn

N. meningitidis cause epidemic & endemic meningitis

90% cases caused by serogroups __

A, B, C, Y; Group B is worldwide cause of bacterial meningtis

N. meningitidis clinical significance

transient bacteremia, or rapidly fatal disease

2nd leading cause of community-acquired meningitis after S. pneumo

meningocephalitis, meningitis w/ or w/o meningococcemia, …

N. meningitidis clin manif

classic: headache, fever, confusion, nuchal rigidity

meningococcemia (petechiae - red spots)

necrotic skin lesions

fulminant shock

DIC - disseminated intravascular coagulation

Waterhouse-Friderichsen syndrome → attack adrenal glands

N. meningitidis virulence factors

polysacc capsule - antiphagocytic

endotoxin = LPS

pili = adhere to mucosal cells of nasopharynx

IgA protease

plasmids

(protein II only one missing - in N. gono)

N. meningitidis acceptable specimens

body fluids: CSF, blood, synovial fluids, pleural fluid, aspirates of petechiae

nasopharyngeal swab for detecting colonization

biopsies

genital, anus, eyes

N. meningitidis risk of lab transmitted infns

need BSC 2, avoid aerosols (beware of this in urine cx!!)

N. meningitidis media

SBA, CHOC, supportive broth medium, other selective media if applicable

incubate 5-10% CO2, moist, 36-37C, at least 72h

N. meningitidis is a ____ in pairs.

col morph?

intracellular GNC

gray, may impart diffuse green color to agar

N. meningitidis is + for which carbohydrates?

glucose & maltose

Which sp of Neisseria is weak sometimes a + glucose reaction?

N. cinerea → may misID as N. gonorrhoeae (they rhyme)

normal oropharyngeal & genital flora

assoc’d w/bacteremia, conjunctivitis, nosocomial pneumoniae & proctitis

other Neisseria ssp

found where?

inhabit mucosal membrane of oral cavity; sometimes genital tract

low virulence, DON’T grow on GC selective media, most grow on nutrient agar, usually susceptible to colisitin

Moraxella catarrhalis

found where

opportunistic pathogen when?

normal upper respiratory flora

otitis media, sinusitis, pneumonia

septicemia, meningitis, endocarditis, conjunctivitis; for infants, immunocomp, COPD pts

Moraxella catarrhalis is an ____ in pairs

col morph

intracellular GNC

col: whiter, more raised than Neisseria; may be pink on choc, may be hockey puck (scoots on agar)

M. catarrhalis ID

carbohydrate utilization?

DNase test

assachrolytic → doesn’t use any sugar

Dnase = pos

Beta-lactamase = pos

butyrate esterase = pos

DNase test

if DNA is depolymerized, toluidine blue turns from blue to rose color → for ID of M. catarrhalis

streak & incubate 35C overnight

pos = rose color

neg = blue

M. catarrhalis enzyme test

butyrate esterase +

uses disk of indoxyl butyrate