Miscellaneous bacteria

Mycobacterium Tuberculosis

• Acid-fast rods, obligate aerobe with mycolic acids in the cell wall.
• Transmission occurs through respiratory droplets.
• Virulence factors include cord factor which inhibits WBC migration, tuberculin that triggers cell-mediated immunity, and sulfatides that prevent phagosome-lysosome fusion.
• Lab studies include the PPD skin test, which indicates current infection or past exposure if positive, QuantiFERON-TB which measures interferon-gamma production, and X-rays.
• Primary TB manifests as the organism replicating in alveolar macrophages within phagosomes, resulting in activated macrophages fighting the infection and causing lung tissue damage, which walls off the infection, forming a Ghon focus.
• Secondary TB occurs when the immune system weakens, allowing the infection to spread to other regions, such as Pott's disease in the bone or Miliary TB in the blood.
• Treatment involves Isoniazid (with Vitamin B6), Rifampin, Pyrazinamide, and Ethambutol (RIPE).

Mycoplasma Pneumoniae

• Classified as a mycoplasma bacteria, lacks a cell wall, and has a cholesterol-containing membrane.
• Transmission is through respiratory droplets.
• Virulence factors involve attachment to respiratory epithelium via protein P1, inhibiting cilia movement, producing hydrogen peroxide that damages epithelium, and acting as a super-antigen.
• It causes pneumonia, commonly in young adults.
• Lab studies show a positive cold agglutinins test and a "fried-egg" appearance on Eaton's agar but is not easily seen on Gram stain.
• Macrolide antibiotics like Erythromycin are used in treatment.

Borrelia Burgdorferi

• Spirochete transmitted by deer ticks (Ixodes).
• Pathogenesis involves tick bites leading to the invasion of skin, blood, heart, joints, and the central nervous system.
• Causes Lyme Disease.
• Stage 1 Lyme disease includes erythema chronicum migrans (target-shaped rash).
• Stage 2 involves neurologic (Bell's palsy, meningitis) and cardiac (AV block, myocarditis) issues.
• Stage 3 results in chronic arthritis.
• Diagnosed through light microscopy, Giemsa stain, and antibody testing (ELISA).
• Treatment includes Doxycycline or Amoxicillin for pregnant women and children under 8, and Ceftriaxone for Stage 2/3.

Treponema Pallidum

• A spirochete primarily transmitted through sex and can also spread across the placenta.
• Causes syphilis, which presents in three stages plus congenital syphilis.
• Primary syphilis presents a painless chancre.
• Secondary syphilis leads to a systemic maculopapular rash on the palms and soles, plus condylomata lata, warty lesions.
• Tertiary syphilis results in gummas (lesions), aortitis, neurosyphilis, and optic problems.
• Primary stage is diagnosed using dark-field microscopy to visualize the spirochetes.
• Secondary stage diagnosis involves VDRL/RPR to check for antibodies against the spirochetes.
• Tertiary stage diagnosis uses FTA-ABS to detect antibodies, which is more specific than VDRL, and VDRL can be negative during this stage.
• Penicillin G is the treatment.

Chlamydia Trachomatis

• Obligate intracellular bacteria requires the host cell's ATP to survive.
• Transmission occurs sexually, perinatally and via hand-to-eye contact.
• Exists in two forms: reticulate bodies which are replicating and visible as inclusion bodies, and elementary bodies, the infectious, inactive extracellular form.
• Diseases vary based on serotypes
• Serotypes D-K cause purulent discharge, urethritis, pelvic inflammatory disease, neonatal pneumonia, and neonatal conjunctivitis.
• Serotypes L1, L2, and L3 cause lymphogranuloma and painful lymphadenopathy.
• Serotypes A, B, and C cause trachoma, a type of conjunctivitis.
• Giemsa stain reveals cytoplasmic inclusions; Immunofluorescence is useful in diagnosis.
• Treatment involves Azithromycin or Erythromycin, particularly for conjunctivitis.

Gardnerella Vaginalis

• A Gram-variable, facultative anaerobic, and nonmotile bacterium.
• Pathogenesis typically occurs due to changes in vaginal flora and pH levels, often resulting from multiple sexual partners, frequent intercourse, or feminine hygiene product overuse.
• It causes Bacterial Vaginosis characterized by a frothy thin gray vaginal discharge with a "fish-like" odor.
• Diagnosed via vaginal swab with a positive KOH whiff test, and by observing clue cells under a microscope.
• Treatment includes Metronidazole or Clindamycin.