Neisseria meningitidis, N. gonorrhea
These are aerobic gram-negative diplococci bacteria. Transmission of N. meningitidis occurs by inhalation. This bacterium colonizes the oropharynx and causes bacterial meningitis in children under 2 years.
N. gonorrhea is found in the genital, cervical, pharyngeal, and anal mucosa. Transmission occurs by sexual route. Causes symptomatic urethritis in men, pelvic inflammatory disease in females, neonatal blindness and sepsis. Spread in blood stream results in septic arthritis in young adults.
PCR following bacterial culture is useful in diagnosis.
Bordetella pertussis
This is a gram-negative coccobacillus bacterium, that infects the respiratory epithelium of larynx, trachea, bronchi. It also invades the macrophage, and transmission occurs by inhalation of respiratory droplets.
Clinical implications: fever, whooping cough, laryngotracheobronchitis.
PCR is mainly useful in diagnosis.
Pseudomonas aeruginosa
This is an aerobic gram-negative bacillus bacterium that is an important cause of opportunistic infection. It affects people with cystic fibrosis & burns, contact with contaminated hospital equipment, drug abusers.
Clinical implications: necrotizing pneumonia; external otitis; sepsis; keratitis (contact lens wearers); endocarditis.
Yersinia enterocolitica, Y. Pseudotuberculosis, Y. pestis
These are gram negative facultative intracellular bacteria. Y. enterocolitica & Y. pseudotuberculosis cause ileitis and mesenteric lymphadenitis. Their transmission occurs through fecal-oral route.
Transmission of Yersinia pestis occurs from wild rodents to humans by fleabite. It causes plague (black death), which is a fatal infection. Clinical implications are: pustular, ulcerative skin lesion (area of fleabite); lymphadenopathy (buboes); pneumonia; sepsis, neutrophilia.
Hemophilus ducreyi
This is a gram-negative bacterium that causes chancroid (soft chancre). Transmission occurs by sexual contact.
Clinical implication: multiple, painful ulcerative lesion on external genitalia.
Klebsiella granulomatis
This is gram negative coccobacilli, that has capsule around it, and causes granuloma inguinale. Spread occurs by sexual contact.
Clinical implication(s): painless, soft ulcerated genital or perineal lesion; genital lymphedema; urethral, vulvar, or anal strictures.
Diagnosis occurs by microscopic examination of exudate with a Giemsa stain.
Treponema pallidum
This is a gram-negative cock-screw like bacterium spirochete. Transmission occurs by sexual contact. It causes primary, secondary, tertiary syphilis & congenital syphilis.
Primary syphilis (PS) occurs 3 wks. after infection, with a single, firm, painless ulcer on the genital or perineal region (chancre). It ends during 3 to 6 wks.
Secondary syphilis begins within 2 to 10 wks. after PS and presents with: maculopapular lesions on palms, soles, oral cavity; plaque lesion (condylomata lata on genital/perineal area; inner thigh or axilla; fever; malaise; lymphadenopathy; weight loss.
Tertiary syphilis occurs after 5 yrs. or more. It causes: syphilitic aortitis; neurosyphilis; nodular lesions (gummas) on skin, subcutaneous tissues, bone, joint.
Congenital syphilis occurs transplacentally and results in Eight nerve-deafness, keratitis, liver fibrosis & Hutchinson teeth.
Diagnosis is by immunofluorescence of exudate; serology tests including Venereal Disease Research Laboratory (VDRL) & rapid plasma reagin tests.
Borrelia recurrentis, B. burgdorferi
These are gram negative cock-screw like bacteria spirochetes. B. recurrentis infection occurs from body-louse bite it is responsible for relapsing fever. It causes: shaking chills; fever, headache; malaise; hepatosplenomegaly; organ failure.
B. burgdorferi transmission is from rodents to humans after deer tick bite, and it is responsible for Lyme disease. It causes: erythema chronicum migrans (redness with pale center on skin); fever; arrhythmias; lymphadenopathy; joint pain; chronic arthritis; joint damage.
Chlamydia trachomatis
This is an obligate intracellular gram-negative bacterium, whose transmission occurs through sexual contact or during vaginal delivery.
Clinical manifestations: asymptomatic urethritis in male; prostatitis; epididymitis; conjunctivitis; pelvic inflammatory disease in females; proctitis; perihepatic inflammation; lymphogranuloma venereum (chronic rupture and ulceration of swollen lymph node); anogenital stricture; ocular infection and trachoma in infants.
Diagnosis by PCR offers better diagnosis.
Rickettsia rickettsii
This is an obligate intracellular gram-negative bacterium that causes Rocky Mountain Spotted Fever (RMSF). Transmission occurs by bite from a dog tick. It infects endothelial vessels of lungs and brain.
Clinical implications: extensive hemorrhagic body rash including palms and soles; pulmonary edema and bleeding; hypovolemic shock; renal failure; peripheral edema; coma.
Diagnosis is by serology testing.
OTHER BACTERIA TYPES
Mycobacterium bovis, M. tuberculosis
These are weakly gram-positive aerobic rod bacteria that grow in chains. M. bovis infection comes from drinking unpasteurized milk, which causes intestinal tuberculosis (ileal ulceration).
M. tuberculosis spread comes from inhalation of respiratory droplet. It infects alveolar macrophages and alveolar spaces. Bacterial culture is the gold standard for diagnosis with acid-fast stain.
Signs and symptoms: low grade fever, malaise, night sweats, upper lobe pneumonia; hilar lymphadenopathy; caseating necrosis, granuloma & cavitation of lung apex; hemoptysis; vertebral tuberculosis (Pott disease); pleural effusion and empyema; unifocal cervical lymphadenopathy.
Mycobacterium avium-intracellulare complex, M. leprae (weakly gram-positive rods)
The M. avium & M. intracullelare are bacteria common in the water, soil, domestic animal. Infection is common among AIDS patients. It causes fever, night sweat, weight loss, lung and G.I problems.
M. leprae spread occurs by inhalation of respiratory droplets. It causes tuberculoid and lepromatous leprosy. In tuberculoid leprosy, skin is dry and scaly with asymmetric peripheral neuropathy.
Lepromatous leprosy include: severe skin thickening with nodule, upper respiratory tract infection, and extensive peripheral neuropathy.
M. leprae highly affects cold areas of skin like soles, earlobes.
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