1. Pathogenic Gram-Negative Cocci (Neisseria)

2. Neisseria
Only genus of Gram-negative cocci that regularly causes diseases in humans
Nonmotile, aerobic bacteria often arranged as diplococci
Distinguished from many other Gram-negative pathogens by being oxidase positive
2 species are pathogenic to humans
The meningococcus, N. meningitidis
The gonococcus, N. gonorrhoeae

5. (virulance factors) pathogenicity
Polysaccharide capsules protect the bacteria from the lytic enzymes within phagocytes
Fimbriae enable them to attach to human cells
Lipooligosaccharide: composed of lipid A (endotoxin) and sugar molecules
IgA protease produced by the bacteria cleaves secretory IgA in mucous
Can easily change its surface antigens leading to evasion of the immune response and multiple infections especially in Neisseria gonorrhoea

6. Neisseria meningitidis
Humans are the only natural carrier of N. meningitidis
Can be a member of the normal microbiota of the upper respiratory tract
Causes life-threatening disease when the bacteria invade the blood or cerebrospinal fluid
Most common cause of meningitis in individuals under 20
Respiratory droplets transmit the bacteria among people living in close contact, especially students living in dormitories, soldiers, prisoners &household contacts
Carriage rate can increase up to 95% during epidemics

7. Neisseria meningitidis
More than 13 known antigenic types
Types A, B, C, Y & W135 are more commonly associated with human disease
Polysaccharide capsules resist lytic enzymes inside phagocytes
Type A, epidemics
Type B, sporadic
Type C, epidemics
Type W135, new outbreaks

10. Neisseria meningitidis
Meningococcal meningitis can result in death as early as 6 hours after initial symptoms
Initial symptoms include fever, sore throat, headache, stiff neck, vomiting and convulsions, photophobia
Meningococcal septicemia, blood poisoning, can also be life threatening
Can produce blood coagulation and the formation of minute hemorrhagic lesions

11. Clinical Findings The two most important manifestations of disease are
-Meningococcemia (Waterhouse-Friderichsen syndrome) characterized by high fever, shock, widespread purpura, disseminated intravascular coagulation, thrombocytopenia, and adrenal insufficiency.
-Meningitis
The symptoms of meningococcal meningitis are those of a typical bacterial meningitis—namely, fever, headache, stiff neck, and an increased level of PMNs in spinal fluid.

14. Examination of the CSF
Its is essential for establishing a proper diagnosis, the CSF profile including glucose, protein determination and WBC count and its diffrencial. It is very important to perform the CSF aspiration before antibiotic therapy

15. CSF profile WBC sugar protein Predominant lymphocyt
Bacteria meningitis Leukocytosis decrease increase
Neutrophils
Predominant
viral or mycobacterium Leukopenia increase decrease
lymphocyt
These changes in the CSF in the bacterial meningitis due to the activated inflammatory cells which release a variety of enzymes that cause tissue damage and increase protein concentration ,at the same time their metabolic activity leads to increase glucose utilization.

16. Diagnosis
Presence of Gram-negative diplococci in phagocytes of the central nervous system

17. Cultural characters They grow on enriched media (chocolate blood agar)
They are exacting in their nutritional requirements, Neisseria gonorrhea being more exacting than Neisseria meningitidis)
The selective medium is Thayer Martin medium (Chocolate blood agar + VCN)
They require extra CO2 for growth especially upon primary isolation.

22. Culture and isolation
The isolation of the Neisseria meningitidis requires special attention because it is fastidious and sensitive to drying and must be plated immediately in fresh ,moist medium,such a s ;
1-Chocolat agar.
2-Thayer- martin ,or modified Thayer –martin medium ,which contain antibiotic such as colistin, vancomycin ,and nystatin ,and the( MTM) contain trimethoprim to inhibit proteus.
3-New York city (NYC),contain lysed horse blood and plasma and antibiotic mainly used to isolate N-gonorrhoeae and mycoplasma.
Colonies ;gray,glistening ,after 24h incubation becoming large ,opaque and irregularat 48h,oxidas-positive (colonies with tetra methyl –p-phenylene diamine rapidly turn to dark purple.

23. Treatment
Meningitis can be effectively treated with penicillin G or ampicillin (both of which can pass the inflamed blood-brain barrier) in large intravenous doses. When the etiology of the infection is unclear, cefotaxime or ceftriaxone is recommended. Prompt treatment reduces mortality to about 10 percent. Because of the intense inflammatory reaction that accompanies bacterial meningitis, many authorities recommend a dose of the corticosteroid dexamethasone shortly prior to, or together with, the first dose of antibiotic.

24. Prevention Prevention Eradication is unlikely due to the
presence of asymptomatic carriers
Vaccination
Prophylaxis: Prophylactic rifampin is given to family members because of the inevitability of their close contact and thus exposure. Other drugs used for prophylaxis include oral ciprofloxacin and intramuscular ceftriaxone.

25. Neisseria gonorrhoeae
Causes gonorrhea, a sexually transmitted disease
Gonococci adhere to epithelial cells of the mucous membranes lining the genital and urinary tracts of humans spreading to deeper tissue as they multiply
As few as 100 pairs of cells are enough to cause disease
Gonorrhea in men
Usually symptomatic producing inflammation that causes painful urination and purulent discharge
Can cause scarring and infertility if prostate and epididymis are involved

26. Neisseria gonorrhoeae
Gonorrhea in women
Often asymptomatic (50%)
Can infect the cervix and other parts of the uterus, including the Fallopian tubes
Can result in pelvic inflammatory disease (PID)
Can result in ectopic pregnancy or sterility
Gonococcal infection of children can occur during childbirth producing inflammation of the conjunctival sac (ophthalmmia neonatorum) and sometimes blindness. Infection of the respiratory tracts can also occur.
Treatment is systemic ceftriaxone IM or IV in a single dose. Infants born to mothers who are known to have a birth canal infected with gonococcus or are at high risk of having this are also given a systemic dose of ceftriaxone prophylactically, even in the absence of clinically evident ophthalmia. Topical erythromycin ointment is only used for routine prophylaxis in circumstances of relatively low risk.

28. Diagnosis and Treatment
Gonorrhea in men can be identified by the presence of Gram-negative diplococci in pus from an inflamed penis, they appear characteristically as gram-negative diplococci intra and extracellular)
Asymptomatic cases can be identified with commercially available genetic probes
Treatment
Ceftriaxone is the treatment of choice in uncomplicated gonococcal infections. Spectinomycin or ciprofloxacin should be used if the patient is allergic to penicillin. Because mixed infections with C. trachomatis are common, tetracycline should be prescribed also.
Penicillinase-producing (PPNG) strains that exhibited high-level resistance were isolated from patients. Penicillinase is plasmid-encoded.
Ciprofloxacin is the treatment of resistance gonorrhea Complicated due to resistant gonococcal strains

29. Prevention Most effective prevention is sexual abstinence
No vaccine is available
Chemical prophylaxis is ineffective
Routine administration of antimicrobial agents to the eyes of newborns successfully prevents ophthalmic disease