gram negative cocci neisseria and moraxella

neisseria gonorrhoeae virulence factors

receptors for human transferrin, capsule, pili, antigenic variation, LPS, IGA protease, beta-lactamase

capsule function

antiphagocytic

pili function

attachment to cells

antigenic variation

immune evasion

LPS function

endotoxin, lipid A moiety and core LOS

IGA protease function

destroys IgA1 immunoglobulin

beta-lactamase

hydrolyses penicillin’s beta lactam ring

neisseria gonorrhoeae pathogenesis

attach to epithelium, spread throughout submucosa, acute inflammatory response, hematogenous spread

neisseria gonorrhoeae clinical manifestations

short incubation period of 2-7 days, genital, rectal, pharyngeal, pelvic inflammatory disease infections, disseminated gonococcal infections, conjunctivitis

genital gonorrhoeae (the clap)

males: acute uethritis, purulent urethral discharge and dysuria, ascending infections can be a complication

Females: endocervix infection, vaginal discharge, urinary frequency, symptoms can be mild or absent, can lead to pelvic inflammatory disease

rectal gonorrhoeae

rectal intercourse, contamination with infected secretions, usually asymptomatic, may cause rectal bleeding

pharyngeal gonorrhoeae

oral/genital, usually asymptomatic, sore throat

pelvic inflammatory disease

extension of disease (endocervix to fallopian tubes), endometriosis and peritonitis, fever, lower abdominal pain, infertility

disseminated infection

bacteremia from any local site, rash, endocarditis, meningitis, purulent arthritis

conjunctivitis and ophthalmia neonatorum

organism introduced into eyes (usually during birth), purulent conjunctivitis, may cause blindess

transmission of neisseria gonorrhoeae

direction transmission through intercourse, vertical transmission

prevention and control of neisseria gonorrhoeae

difficult to control, decreases susceptibility to antibiotics, education programs (promoting safe sex, free condoms)

lab diagnosis of neisseria gonorrhoeae

oxidase positive, gram stain of direct smear of male urethra, gram negative diplococci, usually intracellular, non-motile, non-sporogenous

carbohydrate utilization

CTA carbohydrate test, cystine trypticase agar containing individual carbohydrates and phenol red, requires 24-72 hours, rapid carbohydrate degradation tests read in 2-4 hours, based on presence of preformed enzymes for carbohydrate utilization

other lab tests for neisseria gonorrhoeae

superoxyl test, uses 30% H2O2 and is similar to catalase test, produce immediate vigorous budding, nucleic acid assays( detect gonococcal antigen or nucleic acid directly in cervical, urine, and or uerthral exudates, non amplified and amplified probe methods)

antibiotic resistance of neisseria gonorrhoeae

plasmid mediated penicillinase producing N. gonorrhoeae (PPNG), also exhibits chromosome mediated penicillin resistance (PenR), plasmid and chromosomally mediated resistance to tetracycline and fluoroquinoloes

neisseria meningitidis virulence factors

pili, capsules (used to subdivide into 9 serogroups), endotoxin (damages ciliated cells, causes DIC and petechiae), IgA1 protease, cellular membrane proteins such as PorA and PorB (GC only has PorB)

neisseria meningitidis nasopharyngeal infection

usually asymptomatic, attach to non-ciliated columnar cells, phagocytosed, endotoxin damages adjacent ciliated cells

meningitis

most common form of disease by N. meningitidis, peak incidence in young adulthood (college outbreaks), acute purulent meningitis, abrupt onset severe headache, stiff neck and sometimes fever, petechial rash (distinguishing feature), paralysis, coma, and death

meningococcemia or meningitis bloodstream infections

may occur with or without meningitis, 25% mortality rate, purpura (blood in skin) and petechial rash, tachycardia, hypotension disease, can become fulminant and spread rapidly, DIC, septic shock, waterhouse friderichsen syndrome (hemorrhage in adrenal glands), death may occur within 12-48 hours

neisseria meningitidis epidemiology

natural habitat is mucous membranes, carried in upper respiratory tract, transmission through respiratory droplets (commonly from asymptomatic carriers), close contact (more common in college dorms or military barracks), lack of antibodies

diagnosis of neisseria meningitidis

CSF, blood, nasopharyngeal swabs and aspirates, sputum and urogenital sites,

gram-stained CSF; intracellular and extracellular gram-negative diplococci, encapsulated strains may have halo around organism

neisseria meningitidis culture

selective and non-selective media, grown in 5% CO2, N. meningitidis and non pathogenic neisseria spp will grow on both SBA and CHOC

neisseria meningitidis prevention and control

chemoprophylaxis, vaccines formerly only for military personnel, poor antibody response in young children, reduction of carriers, lab infection: two cases of fatal lab acquired meningococcus in clinical micro lab workers from examining plates and other lab tests

new neisseria meningitidis vaccine

menectra, approved in 2005 by FDA for people 11-55 yo, polysaccharide antigens conjugated to diphtheria toxoid protein, expected to provide long term immunity, vaccine recommended for young teens, especially college freshman living in dorms, military recruits, people missing a spleen, and those traveling to endemic countries

neisseria meningitidis treatment

penicillin, penetrates meninges

media used for GC

chocolate or selective

media used for MC

blood or selective

cultivation of neisseria

modified thayer martin agar, martin lewis agar, new york city agar, antimicrobials: vancomycin for gram positive, colistin for other gram negatives, trimethoprim for proteus. antifungals: ystatin anisomycin, amphotericin B

neisseria growth characteristics

pathogens: fastidious (GC dies quickly outside of body), enhanced growth with CO2, prefer 35-37 degrees, small, glistening colonies, 1-2 days incubation

non-pathogens: non-fastidious, aerobic, growth at RT

neisseria morphology and staining

gram negative diplococci, flattened on one side, coffee bean or kidney bean shaped, non-pathogens larger than pathogens, usually intracellular, non-motile, non-sporogenous

gonorrhoeae diagnosis

usually diagnosed directly from gram stain of male urethral discharge, cannot diagnose directly in females due to their normal flora

meningitis diagnosis

CSF and blood, skin lesions, symptoms

moraxella catarrhalis general features

formerly neisseria and then branhamella, part of upper respiratory tract, gram negative coccobacilli, oxidase positive, catalase positive, produce DNAse, non-fermentative, unable to reduce nitrates to nitrites

moraxella catarrhalis clinical manifestations

isolated only from humans, commensal of upper respiratory tract, opportunistic pathogen, causes upper respiratory tract infections in children and elderly, causes lower respiratory tract infections in adults with existing lung disease, 3rd most common cause of otitis media and sinusitis in children, sever infections in immunocompromised hosts

moraxella catarrhalis treatment

produce beta lactamase making them resistant to ampicillin and amoxicillin, usually susceptible to erythromycin, tetracycline, trimethoprim sulfa, ampicillin with beta lactamase inhibitor

moraxella catarrhalis diagnosis

organism will grow on SBA, and CHOC producing small grey to white colonies, described as hocky puck because it remains intact when pushed across the plate with a loop, usually inhibited by colistin present on gonococcal selective media, oxidase and catalase media asaccharolytic

N. cienera

can be misidentified as gonococcus using some commercial ID systems, similar morphology to gonococcus but is susceptible to colistin, negative DNAse

N. flavescens

yellow pigment, asaccharolytic, grows on SBA and CHOC at room temp

N. lactamica

common commensal in nasopharynx of infants and children, carriage rate peals at 2 years of age, rarely isolated from adults, the only neisseria spp that utilizes lactose. morphologically to meningococcus, able to grow on selective media and is glucose and maltose positive, positive ONPG

N. mucosa

large colonies that adhere to the agar, mucoid, isolated from nasopharynx of children and young adults as well as the airways of dolphins, can cause pneumonia in children, ability to reduce nitrite to nitrogen gas, lacks pigments

N. sicca

colonies dry, wrinkled, adherent and breadcrumb like, common commensal of respiratory tract of adults

N. subflava

subflava means less yellow, able to grow on SBA and CHOC at room temp

kingella denitrificans

able to reduce nitrate, normal flora un upper respiratory tract, rarely causes disease, associated with endocarditis, is a gram negative rod but can display coccoid forms, negative catalase