2014 neisseria lec.

Neisseriaceae:ByAssist prof :Eman Abdul-Aziz

Neisseriaceae:
Family :Neisseriaceae include the genera Neisseria,Moraxella. Tow species of Neisseria are pathogenic for human N. gonorrheae ; N. meningitidis.

Non pathogenic Neisseria include : N. mucosa, N. lactamica. N. sicca They are members of indigenous flora including oral mucosa.


#Non motile#Gram negative#Kidney shaped usually arranged in pairs#Oxidase +#Pathogenic Neisseria have fastidious growth requirements, while non pathogenic species which are often part of the normal flora can grow on ordinary media.
General characteristics:

Gram negative diplococci (pairs of cocci) oxidase positive

( Capnophilic )5-10% CO2 Thayer Martin. selective chocolate agar heated blood
Neisseria

N. gonorrheae

Habitat and transmission: The human urogenital tract is the usual habitat ,oral nasopharyngeal and rectal carriage in healthy individuals is not uncommon. Spread is by both homosexual and heterosexual contact.

Characteristcs :

Non motile Non capsulated diplococci . Gram negative.

Culture and Identification:

Specimens are usually inoculated on an enrichment medium and incubated under ( 5-10 )%CO2 { capnophilic}, colonies are small, grey, then become large. Oxidase positive ,produce acid from glucose but not from maltose or sucrose.

Pathogenicity:

Gonococci possess a number of virulent attributes : # Pili allow gonococci to adhere and colonize epithelial surfaces and case infections. # IgA protease produced by some gonococci break the heavy chain of immunoglobulin A. #Some N. gonorrheae. Produce B lactamase. #A tracheal cytotoxin damage the ciliated cells of the fallopian tube, leading to sterility.


Pili = key in anchorage of organisms to mucosal epithelium. Nonpiliated gonococci are avirulent
Neisseria gonorrhoeae

Treatment and prevention :

B – lactamasee Cephlosporins (for gonococci that are resistant to B-lactam drugs).Prevention of gonorrhoeae requires the practice of safe sex.

N. meningitidis (the "meningococcus")

N.meningitidis

Habitat and transmission: The main reservoir is the nasopharynx of normal people (10-15)%.Droplet spread is the common transmission mode.

Characteristics :

Resembles to gonococcus but N.meningitidis cells are capsulate.

Culture and Identification :

Is made by observing gram negative cocci in pairs in nasopharyngeal discharge,CSF or blood smear. Selective media are not required as the organism is found pure in C.S.F. fluid. Production of acid from the oxidation of glucose and maltose.

#Meningococci spread from the nasopharynx in to the blood stream (septicemia)and then to the meninges. #Eventual death may be due to meningitis or adrenal haemorrhage (water house-fridshen syndrome). #The antiphagocytic properties of the capsule help dissemination while toxic effect are mainly due to meningococcal endotoxin .
Pathogenicity:

Capsule

LPS
N. meningitidis
Virulence FactorsSimilar, but –Differencesin utilization Hemolysin IgA protease
PILI Opacity (OPA) proteins Outer Membrane Proteins
N. gonorrhoeae
LPS
PILI Opacity (OPA) proteins Outer Membrane Proteins
IgA protease
NO capsule NO hemolysin
X

Treatment:

Penicillin or cefotaxime.

Commensal Neisseria species:

*Are common in oral cavity,nose and pharynx ,some times in female genital tract. The 3 main species are N.subflava, N. mucosa and N.sicca. Grow on ordinary agar at room temp.In the absence of Co2

Non pathogenic and are almost always found in oral specimens contaminated with saliva or mucosa. *N.species are among the earliest colonizers of clean tooth surface. *They consume O2 during the early plaque formation and facilitate subsequent growth of facultative&anaerobic late colonizer.

Moraxella:

#G- cocci,closely related to non pathogenic. #Asaccharolytic and non pigmented. #Commensals of human R.T. #Opportunistics m.o.causing meningitis,endocarditis,otitis media,maxillary sinusitis and chronic obstructive air ways disease. #ProduceB-lactamase.

Veillonella:

#Obligate anaerobic #Gram negative cocci

Oral species are 

1-V.parvula 2-V. dispar 3-V.atypica


Grame negative anaerobic cocci #Found in the human oral cavity(mostly in dental plaque) #They are benevolent m.o. in relation to dental caries ,as they metabolize the lactic acid produced by cariogenic bacteria in to weaker acids (acetic and propionic)with a reduced ability to solubilize enamel.
V.parvula

Parvobacteria

They are miscellaneous,heterogenous group of small gram negative bacilli which cause a number of different diseases. 1-Haemophilus 2-Brucella 3-Bordetella 4-Pasteurella 5-Actinobacillus 6-Gardnerella 7-Eikenella

Haemophilus spp.

Tiny , non motile, aerobic, gram negative , coccobacilli. *Some are capsulated *Requires (xand v)factors X factor =haematine present in blood V factor =nicotin amid adenine dinucleotide (NAD)orNAD phosphate, a vitamine obtained from yeast and vegetable extracts or ametabolic products obtained from most bacteria including Staph. aureus

H . influenza:

Habitat and transmission: #Upper respiratory tract commensal of humans and associated animals. #The major aetiological agent of U.R.T. infections and acute exacerbation of chronic bronchitis. #Is a common secondary colonizer of the respiratory after a bout of influenza (influenza virus).

Characteristics:

Small gram negative , non sporing, non motile rods Virulent strains isolated from C.S.F. in meningitis are capsulated.#Typically forms large colonies around colonies of other m.o. that secrete v factor this phenomenon called Sateilitism. If blood agar plate containing x factor seeded with H. influenza is streaked with Staph. aureus, which secretes v factor) and incubated over night at 37 °Ċ the former will grow as large colonies adjacent to the streak of Staph. aureus..

Sateilitism Syndrome of H. influenza

Pathogenisity:
Meningitis Acute epiglottitis Osteomylitis Arthritis The most important virulence factor of H. influenzae is the polysaccharide capsule, IgA protease.

Treatment and prevention:

Ampicillin for B-lactamase negative strain. Prevention by vaccination(Hib)against type b influenza. Close contacts of meningitis cases should be given Rifampicin.

Bordetella:

B. pertusis is the agent of whooping cough. Found in human respiratory tract in diseased individuals Healthy carriage is not known. Spread by air borne route.

Characteristics:

Short ,some times oval ,gram negative rods. Fresh isolated may be capsulated. Fastidious growth requirements.


Requires a special enrichment media (Bordet-Gengou-Medium), (Blood-charcoal agar, with antibiotics) Incubation for 3-5 days at 35Ċ. Iridescent colonies resembling mercury drops upper on Bordet –Gengou medium. Identification is confirmed serologically Culture and Identification

Pathogenicity:

#Whooping cough especially in preschool children (sever in those under 12 months). #The characteristics symptom is the bout of paroxysmal coughs followed the whoop of rapid inhalation after coughing. #Virulance factors are: Tracheal cytotoxin, fimbrial antigen and endotoxin.

Treatment and prevention:

Erythromycin is the drug of choice for patients and close contacts. Prevention: by the whole-inactivated cell vaccine a cmponent of the Diphtheria-Tetanus-Pertusis(DTP) vaccine of childhood.

Actinobacillus actinomycetemcomitans

*Isolated from the oral cavity. *So named because its frequently isolated with Actinomyces spp. from actinomycotic lesion. *Multiple biotypes and 5serotypes(a-e)have been described. This species is a major infective agent in particularly aggressive forms of periodontal disease in adolescents and rapidly destructive periodontal disease in adult.

Habitate and transmission:

# Is likely to be sub gingival sites of humans and mammals #Infections is endogenous.

Characteristics:

*Small short straight or curved rods with rounded ends*Electron microscopic studies have revealed bleb –like structures on the cell surface ,which appear to be released from the cells.

Culture and identification:

#Grows best with 5-10%Co2. #Grows as white ,translucent ,smooth ,non hemolytic colonies on blood agar. #Selective media for identification,Tryptone-Soy-Serum bacitracin -Vancomycin agar,yields white,translucent colonies with star-shaped internal structure. #Identification by sugar fermentation and assimilation reactions and acid end products of C.H.O. metabolism.

A star shaped colony of A.a.

Pathogenicity: 
#Virulence factors including L.P.S., endotoxin,leucotoxin,collagenase and protease #Leucotoxin is thought to play a significant role in subverting the host immune response in the gingival crevice. *Together with other coagents,is involved in localized aggressive peridontitis and destructive periodontal diseases in adult. #Isolation from endocarditis, brain and sub cutaneous abscesses.

Treatment:

sensitive to tetracycline.

Eikenella; ex. E.corrodens

Resemble H. influenza . *Commensal in the human oral cavity and intestine. *Are capnophilic,G-, short coccobacillary forms which are asaccharolytic. *When grown on selective media they corrode the agar surface( hence the name corrodens). *Human infection usually results from predisposing factors (trauma to mucosal surface) which allow the m.o. access to surrounding tissue,thus may cause extra oral infections, including brain and abdominal abscesses, peritonitis, endocarditis,osteomylitis and meningitis.

Capnocytophaga:

*This genus was created for fusiform species isolated from periodontal pockets. *Unlike Fusobacterium and Bacteriodes spp., grow under capnophilic conditions. *They have a characteristics ability to glide over blood agar(compare swarming of Proteus spp)

C. ochracea C. gingivalis C. granulose C sputigena C. haemolytica

.

Characteristics:

#Long, thin fusoform m.o. #Gilding motility seen on bright-field microscopy. Culture and Identification: *Facultative anaerobes, mostly require Co2 for growth. *Colonies on agar surface spread with uneven edges and may pink ,yellow or white . *Identification by cell morphology, biochemical tests and acid products.

* Opportunistics pathogens. *Some times associated with gingivitis and other systemic infections immune compromised patients. *Some strains produce IgA protease.
Pathogenicity: