Batterjee Medical College

Batterjee Medical College

Aerobic Gram-Negative Cocci

Dr. Manal El Said

Head of Microbiology Department

Batterjee Medical College

Neisseria

Dr. Manal El Said

Head of Microbiology Department

Batterjee Medical College

Neisseria meningitidis (Meningococcus)

Diseases Meningitis (inflammation the meninges of the brain or spinal cord) Meningococcemia . Characteristics

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Gram-negative " kidney-bean " diplococci. Oxidase-positive.

Large polysaccharide capsule . One of the three classic encapsulated pyogenic bacteria (Streptococcus pneumoniae and Haemophilus influenzae are the other two).

Habitat and Transmission

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Habitat is the human upper respiratory tract

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Transmission is via respiratory droplets .

Batterjee Medical College

Neisseria meningitidis (Meningococcus)

Pathogenesis

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The organism reaches the meninges via the bloodstream .

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Endotoxin in cell wall causes symptoms of septic shock .

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IgA protease produced.

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Capsule is antiphagocytic.

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Deficiency in late complement components recurrent meningococcal infections .

The characteristic skin rash (purpura) of meningococcal septicemia,

Neisseria meningitidis

caused by

Batterjee Medical College

Neisseria meningitidis (Meningococcus)

Laboratory Diagnosis

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Gram-stained smear and culture.

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Oxidase-positive colonies on chocolate agar.

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Ferments maltose in contrast to gonococci, which do not.

Batterjee Medical College

Neisseria meningitidis (Meningococcus)

Laboratory Diagnosis Round, moist, glistening & convex colonies N. meningitidis - proper streaking and growth on blood agar plate

.

Batterjee Medical College

Neisseria meningitidis (Meningococcus)

Laboratory Diagnosis Glu + + Mal Lac Suc

Batterjee Medical College

Neisseria meningitidis (Meningococcus)

Treatment Penicillin G (no significant resistance).

Prevention

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Vaccine contains capsular polysaccharide of strains A, C, Y & W-135.

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One form of the vaccine contains the polysaccharides coupled to a carrier protein (diphtheria toxoid) and one contains only the polysaccharides .

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Rifampin or ciprofloxacin given to decrease oropharyngeal carriage.

close contacts to

Batterjee Medical College

Neisseria gonorrhoeae (Gonococcus)

Diseases

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Gonorrhea.

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Neonatal conjunctivitis

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Pelvic inflammatory disease.

Characteristics

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Gram-negative "kidney-bean" diplococci.

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Oxidase-positive.

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Insignificant capsule.

Batterjee Medical College

Neisseria gonorrhoeae (Gonococcus)

Habitat and Transmission

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Habitat is the human genital tract .

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Transmission in adults is by sexual contact .

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Transmission to neonates is during birth .

Pathogenesis

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Organism invades mucous membranes inflammation.

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Endotoxin weaker than that of meningococcus less severe disease when bacteremiaoccurs.

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IgA protease & pili are virulence factors

Batterjee Medical College

Neisseria gonorrhoeae (Gonococcus)

Laboratory Diagnosis

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Gram-stained smear and culture.

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Organism visible intracellularly exudate. within neutrophils in urethral

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Oxidase-positive colonies.

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Gonococci do not ferment maltose (meningococci do). Left: Neisseria gonorrhoeae Gram stain of pure culture; Right: Neisseria gonorrhoeae Gram stain of a pustular exudate.

Batterjee Medical College

Neisseria gonorrhoeae (Gonococcus)

Laboratory Diagnosis

Batterjee Medical College

Neisseria gonorrhoeae (Gonococcus)

Treatment

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Ceftriaxone for uncomplicated cases.

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Tetracycline added for urethritis caused by

Chlamydia trachomatis.

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High-level resistance to penicillin is caused by plasmid encoded penicillinase.

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Low-level resistance to penicillin is caused by reduced permeability and altered binding proteins.

Batterjee Medical College

Neisseria gonorrhoeae (Gonococcus)

Prevention

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No drug or vaccine.

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Trace contacts and treat to interrupt transmission.

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Treat eyes of newborns with erythromycin ointment or silver nitrate to prevent conjunctivitis.

Batterjee Medical College

Moraxella catarrhalis

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Small coccobacillary gram-negative rod

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It causes : Otitis media & sinusitis in children.

Bronchitis & pneumonia in older people with chronic obstructive pulmonary disease

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It is found only in

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It transmitted by humans respiratory aerosol .

Batterjee Medical College

Anaerobic Gram-Negative Cocci

Dr. Manal El Said

Head of Microbiology Department

Batterjee Medical College

Veillonella

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Veillonella parvula

is an anaerobic gram-negative diplococcus

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It is a normal flora of the mouth, colon & vagina .

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It is a rare opportunistic pathogen that causes abscesses of the sinuses, tonsils & brain

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It is usually in mixed anaerobic infections.