BIO NMDCAT

The correct option is Opportunistic infections/diseases. Because HIV destroys CD4 T-cells, the immune system cannot fight off organisms that normally do not cause disease in healthy individuals. These are termed opportunistic infections and define the onset of clinical AIDS.

The correct option is Jarisch-Herxheimer reaction. This is a classic reaction occurring within hours of antibiotic treatment for spirochetal infections, caused by the massive release of antigens from dying bacteria triggering a strong inflammatory response.

The correct option is The bacteria have entered the bloodstream, initiating the secondary stage. The primary chancre heals spontaneously after 3-6 weeks, even without treatment. This does not mean a cure; rather, the spirochetes disseminate systemically, leading to secondary syphilis.

The correct option is Treponema pallidum. This describes late congenital syphilis. T. pallidum can cross the placenta, infecting the fetus and causing severe developmental anomalies known as the Hutchinson's triad.

The correct option is Asymptomatic carriers. Many women with cervical gonococcal infections experience mild or no symptoms initially. Unaware of their infection, they do not seek treatment and continue to transmit the bacteria to sexual partners.

The correct option is Treponema pallidum. Tertiary syphilis can present as neurosyphilis, causing progressive degeneration of the central nervous system (e.g., tabes dorsalis and general paresis/dementia) years or decades after the initial infection.

The correct option is Synthesis of viral DNA from the viral RNA genome. Reverse transcriptase is responsible for converting the single-stranded viral RNA into double-stranded proviral DNA. Inhibiting it stops viral replication at this step.

The correct option is Reactivation of latent virus migrating down sensory nerves. Stress temporarily weakens the immune system, allowing latent HSV residing in the sensory ganglia to reactivate, travel anterograde down the axon, and cause new lesions on the epithelium.

The correct option is Are generally incurable and managed symptomatically. Bacterial STDs (syphilis, gonorrhea) can be cured with appropriate antibiotics. Viral STDs (herpes, HIV) integrate or become latent in host cells and are currently incurable; treatments only manage symptoms and reduce viral load.

The correct option is Dead neutrophils, cellular debris, and bacteria. The body's immune response to Neisseria gonorrhoeae involves a massive influx of polymorphonuclear leukocytes (neutrophils). The resulting pus (purulent discharge) consists of dead host cells, neutrophils, and the ingested bacteria.

The correct option is Condylomata lata. These are characteristic mucocutaneous lesions of secondary syphilis occurring in moist skin folds. They are teeming with spirochetes and are highly contagious. Gummas are tertiary, and chancres are primary.

The correct option is CD4+ T-helper lymphocytes. HIV uses the CD4 receptor to enter and eventually destroy T-helper cells. The loss of these orchestrator cells severely impairs both humoral and cell-mediated immune responses, leading to AIDS.

The correct option is Neisseria gonorrhoeae. When a newborn passes through a birth canal infected with gonorrhea, the pathogen can infect the eyes, causing ophthalmia neonatorum. Routine prophylactic eye drops (e.g., erythromycin) are given to prevent this.

The correct option is Latent stage. Following the disappearance of secondary stage symptoms, syphilis enters a latent phase where the patient is asymptomatic but retains the spirochetes in tissues, maintaining positive blood tests for antibodies.

The correct option is Granulomatous lesions resulting from hypersensitivity reactions to remaining spirochetes. Gummas are soft, non-cancerous granulomatous growths that characterize tertiary syphilis. They are essentially a destructive delayed hypersensitivity immune response to localized persistent spirochete antigens.

The correct option is Dark-field microscopy. T. pallidum is too thin to be seen with standard bright-field microscopy and Gram stains poorly. Dark-field microscopy illuminates the live, motile spirochetes against a dark background, allowing immediate identification.

The correct option is Ectopic pregnancy. Scarring in the fallopian tubes restricts the passage of a fertilized ovum to the uterus, causing the embryo to implant within the tube (ectopic pregnancy), which is a life-threatening emergency.

The correct option is Antibiotics target bacterial cellular structures absent in viruses. Antibiotics (like penicillin) disrupt bacterial-specific processes like cell wall synthesis. Herpes is a virus, which lacks these structures and replicates inside host cells, rendering antibiotics completely ineffective.

The correct option is Fimbriae (pili) for firm adherence. N. gonorrhoeae possesses specialized pili that allow it to anchor securely to the mucosal epithelial cells of the genitourinary tract, preventing it from being mechanically flushed out by bodily fluids.