Gram Negative Cocci and Meningitis Lecture Notes PDF

Gram negative cocci & Epidemic Meningitis Microbiology Department Dr.Mohamed Elmutasim Mon. Feb. 21. 2018 Objectives: To Study: 1/ Diseases causes by gram negative cocci, diagnosis, treatment and prevention. 2/ Epidemic meningitis Introduction All of the organisms are Gram-negative cocci...

Gram negative cocci & Epidemic Meningitis Microbiology Department Dr.Mohamed Elmutasim Mon. Feb. 21. 2018 Objectives: To Study: 1/ Diseases causes by gram negative cocci, diagnosis, treatment and prevention. 2/ Epidemic meningitis Introduction All of the organisms are Gram-negative cocci or coccobacilli and all are oxidase positive with the exception of Acinetobacter. Moraxella and Neisseria are catalase positive and Kingella are catalase negative. Neisseria meningitidis (Meningococcus) Diseases: -Meningococcus, an obligate human bacterial pathogen, remains a worldwide and devastating cause of epidemic meningitis and sepsis. - Meningitis (inflammation the meninges of the brain or spinal cord) - Meningococcemia. Habitat is the human upper respiratory tract Transmission is via respiratory droplets. Neisseria meningitidis (Meningococcus Diagnosis: 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). Neisseria meningitidis (Meningococcus Risk factors for meningitis include: -Skipping vaccinations. -Age. -Living in a community setting. This is probably because the bacterium is spread through the respiratory route, and spreads quickly through large groups. -Pregnancy. Weakened immune system -Environmental as less humidity Neisseria meningitidis (Meningococcus) Pathogenesis: The organism reaches the meninges via the bloodstream. Endotoxin in cell wall causes symptoms of septic shock. IgA protease produced. Capsule is antiphagocytic. The characteristic skin rash (purpura) of meningococcal septicemia, caused by Neisseria meningitidis Neisseria meningitidis (Meningococcus) Treatment: Penicillin G (no significant resistance). Prevention: Vaccine contains capsular polysaccharide of strains A, C, Y & W-135. One form of the vaccine contains the polysaccharides coupled to a carrier protein (diphtheria toxoid) and one contains only the polysaccharides. Rifampin or ciprofloxacin given to close contacts to decrease oropharyngeal carriage. Neisseria gonorrhoeae (Gonococcus) Diseases: Gonorrhea. Neonatal conjunctivitis Pelvic inflammatory disease. Habitat is the human genital tract. Transmission in adults is by sexual contact. Transmission to neonates is during birth. Diagnosis: Gram-negative "kidney-bean" diplococci. Oxidase-positive. Insignificant capsule. Neisseria gonorrhoeae (Gonococcus) Treatment: Ceftriaxone for uncomplicated cases. Prevention: No drug or vaccine. Trace contacts and treat to interrupt transmission. Treat eyes of newborns with erythromycin ointment or silver nitrate to prevent conjunctivitis.  Moraxella catarrhalis Small coccobacillary gram-negative rod It causes : -Otitis media & sinusitis in children. -Bronchitis & pneumonia in older people with chronic obstructive pulmonary disease It is found only in humans It transmitted by respiratory aerosol. Anaerobic: Gram-Negative Cocci: Veillonella parvula Veillonella parvula is an anaerobic gram-negative diplococcus It is a normal flora of the mouth, colon & vagina. It is a rare opportunistic pathogen that causes abscesses of the sinuses, tonsils & brain It is usually in mixed anaerobic infections. Thank You