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Gram-Negative Cocci (Neisseria Meningitidis (Epidemiology &…
Gram-Negative Cocci
Neisseria Meningitidis
Epidemiology & Pathogenesis -Prevalent cause of meningitis; sporadic or epidemic-Transmitted by respiratory secretions/droplets from infected carriers-Exclusively human reservoirs, specifically in the nasopharynx; 3-30% of adult population has meningitis; higher in institutional settings-High risk individuals:
- People living in tight living spaces
- Children 6 mos. - 3 yrs.
- Children & adults 10 - 20 yrs.
-Disease begins when bacteria enter bloodstream, pass into cranial circulation & multiply in meninges-Very rapid onset w/ neurological symptoms-Endotoxin causes hemorrhage & shock-Can be fatal
Clinical Diagnosis
-Gram stain of CSF, blood, or nasopharyngeal sample
-Culture tests for differentiation
-Rapid tests for capsular antigen
Treatment & Prevention
-Treated w/ IV penicillin G & chloramphenicol
-Prophylactic treatment of family members, medical personnel, or children in close contact w/ patient
-Use of vaccines for groups A (all ages) & C (only individuals over 2yrs. of age)
Virulence Factors
-LPS endotoxin; causes cardiac failure, vascular collapse & clotting factors
-IgA protease
-Pili & Capsule
Neissera Gonorrhoeae -AKA "The Gonococcus"-Causes gonorrhea, an STD -Virulence factors:
- Pili & other surface molecules for adhesion; slows phagocytosis
- IgA protease; cleaves secretory IgA
-
Gonorrhea
-Infection that is asymptomatic in 10% of males & 50% of females
-Strictly human reservoirs
Effects on Females
-Vaginitis
-Urethritis
-Salpingitis/PID (Pelvic Inflammatory Disease)
-Sterility
-Ectopic tubal pregnancies
-
Extragenital Infections
-Anal infections
-Pharyngeal infections
-Conjunctivitis
-Septicemia
-Arthritis
Effects on Newborns -Newborns are infected as they pass through the birth canal
-Causes eye inflammation & blindness
-Prevented by prophylaxis immediately after birth
Diagnosis & Control
-Gram stain: Gram-Negative intracellular (neutrophils) diplococci from urethral, vaginal, cervical, or eye exudate; creates presumptive identification
-20-30% of new cases are penicillinase-producing (PPNG) or tetracycline resistant (TRNG)
-Combined therapies required due to resistance to penicillin
-Recurrent infections can occur
-A reportable infectious diseases
Epidemiology & Pathology
-Strictly a human infection -In top 5 STDs
-Infectious Dose = 100 - 1,000 colony-forming units
-Does not survive more than 60-120 mins. on fomites
Other
-
Genus Acenetobacter
-Gram-Negative bacilli
-Have non-living reservoirs (soil & water)
-Source of nosocomial infections
Genus Branhamella
-Branhamella catarrhalis is found in the nasopharynx; causes opportunistic infections in patients wi/ cancer, diabetes & alcoholism
Family Neisseriaceae -Gram-Negative Cocci -Residents of mucous membranes of warm-blooded animals-Genera include Neisseria, Moraxella & Acenetobacter-2 Primary human pathogens:
- Neisseria gonorrhoeae
- Neisseria meningitidis
Genus Neisseria
-Gram-Negative, bean-shaped dipplococci
-No flagella or spores
-Pathogens have capsules
-Have pilli
-Strict parasites, do not survive long outside the host
-Can be aerobic or microaerophilic
-Oxidative metabolism
-Produce catalase & cytochrome oxidase
-Pathogenic species require enriched media & CO2