7. Neisseria spp Flashcards
what are they?
gram -ve diplococci
what are the pathogenic / non-pathogenic Neisseriae spp?
Pathogenic: -Neisseria meningitidis -Neisseriae gonorrhoeae Non- pathogenic - Commensals in nasopharynx
Neisseria gonorrhoeae?
- fastidious gram -ve diplococci (bean-shaped)
- grow at 37C lysed blood & chocolate agar in 5-10% CO2
- oxidase positive
- identication: glucose utlitization—> acid
( test: sugars added to agar Neisseria gonnorhoea only uses glucose (bc of acid production))
Neisseria gonorrhoeae pathogenicity?
- fimbriae or type IV pili attachment to mucosal surface (target site for pili attachment for entrance point of pathogen into cells causing disease)
- resistance to intracellular killing by phagocytic cells by production of catalase that protect the organism from effect of toxic O2 radicals
- Antigen variation of fimbriae and outer memebranw protien II (mutation during DNA replication) (of the mutation, whenever the m.o. enters the body it’s as if it’s a new m.o.)
Clinical features of Neisseria gonorrhoeae?
- never normal flora
- Local infections
~ acute urethirits in males
~ 95% symptomatic (male) ( 50% females)
~ dysuria, urethral discharge
~ local spread: epididymitis, prostatitis, urethral stricture
Clinical features of Neisseria gonorrhoeae?
- Acute vaginitis & endocervicitis
- 50% of females symptomatic
- pelvic inflammatory disease
- salpangitis
- infertility
- opthalamia neonatorum
Clinical features of Neisseria gonorrhoeae?
- disseminated gonococcal infection
~ common in female
~ fever, arthritis, septic skin lesions on extermities
~ RARELY: mebingitis, infective endocarditis
Clinical features of Neisseria gonorrhoeae?
- vulvovaginitis in prepubertal girl
~ child abuse
Neisseria gonorrhoeae diagnosis?
~ urethral (male), endocervical (female) swabs
~ culture & sensitivity
~ non culture methods: detect nucleic acid by PCR
Neisseria gonorrhoeae Treatment?
~ both patient & partner
~ ceftriaxone or spectinomycin
~ ciprofloxacin: resistance
Neisseria gonorrhoeae Control?
- adequate diagnosis, treatment
- contact tracing
- prevention: condom, barriers methods
- screening for high-risk indivitual
- prevent opthalmia neonatorum: 1% silver nitrate in eyes of all newborn in high prevalence area
Neisseria meningitidis?
- Fastidious aerobic gram -ve diplococci (bean- shaped)
- grows on 37C on blood & chocolate agar
- oxidase positive
- identification: glucose & maltose = positive
- viability: organism die quickly at room temperature outside human host
Neisseria meningitidis?
- it produces polysaccharide capsule which is the base for serogroup typing system
- 13 serogroup: commonest A, B,C, X, Y,Z,W-135
- typing: slide aggulination with specific antisera
Neisseria meningitidis epidemiology?
- reservoir: human nasopharynx
- carriers (20%), 50% non capsulated i.e. non-pathogenic
- epidemics: carriers 90%
- risk factors
~ lack of bactericidal antibodies
~ age: 3 months — 3 yrs, 18-23 yrs
~ travel to edemic areas ( africa, mecca)
~ complement deficieny
~ splenectomy
Neisseria meningitidis pathogenesis?
- type IV pilus: mucosal colonization of nasopharynx
- organism cross nasopharynx —> circulation
- polysaccharide capsule resist host immune defense
Neisseria meningitidis clinical features?
- meningitis, septicemia
- conjunctivitis, artheritis, infective endocarditis
Neisseria meningitidis virulence factors?
- polysaccharide capsule: prevent phagocytosis
- LOS endotoxin: present in the outer membrane of N. mengitidis, damage to blood vessels associated w/ meningococcal infection
- lipooligosacchride: stimulates TNF-alpha results in host cell damage
Neisseria meningitidis laboratory diagnosis?
- CBC
- blood culture
- CSF
~ cell count: WBC (PMN)
~ glucose (less), protein (more)
~ culture
~ direct antigen detection
*serogrouping: slide agglutination test
*PCR: blood or CSF
Neisseria meningitidis treatment?
- treatment
- penicillin
- ceftriaxone
- chemoprophylaxis
- rifampicin or ciprofloxacin for both patient & contacts
- notification to public health department
- Immunoprophylaxis: serogroups A,B,C,Y, W-135
- infection control
- isolation of patient for 2 days
Moraxella catarrhalis?
- Aerobic gram -ve diplococci
- grow at 37C on blood agar & chocolate agar
- oxidase: positive
- DNase: positive
- Commensals in upper resp tract
Moraxella catarrhalis clinical features?
- Otitis media
- sinusitis
- lower resp tract infections in chronic obstructive pulmonory disease especially elderly
- bacteraemia esp. immuno-compromised patients
Moraxella catarrhalis virulence factors?
- outer membrane proteins (OMPs)
- Lipo-oligosacharide (LOS): initial stage of attachment to nasopharynx
- pilli
Moraxella catarrhalis treatment?
- amoxicillin-clavulanic acid (beta-lactamase +ve)
- cephalosporins
