MCQs

The correct option is Highly susceptible to drying, requiring direct moist contact for transmission. Enveloped viruses derive their lipid bilayer from host cell membranes. This envelope is fragile, making the virus susceptible to drying and detergents, thus requiring direct intimate contact for successful transmission.

The correct option is Contain high numbers of spirochetes and are highly infectious. Secondary syphilis is marked by systemic mucocutaneous lesions (rash, mucous patches) that are laden with Treponema pallidum, making this stage extremely contagious through contact.

The correct option is Microtubule-associated motor proteins within the axon. The virus enters the sensory nerve endings and exploits the neuron's microtubule transport system (dynein motors) to travel retrograde up the long axon to the cell body in the ganglion for latency.

The correct option is Gonorrhea. Untreated gonorrhea (along with Chlamydia) is a leading cause of pelvic inflammatory disease (PID), which scars the fallopian tubes and heavily predisposes women to ectopic pregnancies.

The correct option is Utilize RNA-dependent DNA polymerase to synthesize DNA from an RNA template. Retroviruses possess an RNA genome and the enzyme reverse transcriptase, which reverse-transcribes their RNA into DNA, a process essential for integrating into the host's genome.

The correct option is Positive specific treponemal antibodies in cerebrospinal fluid (CSF). Neurosyphilis involves central nervous system invasion. Examining the CSF for elevated proteins, white blood cells, and positive syphilis serology confirms tertiary neurosyphilis.

The correct option is The infection involved a penicillinase-producing or drug-resistant strain. Neisseria gonorrhoeae is notorious for acquiring antibiotic resistance mechanisms, such as plasmids carrying penicillinase, making standard therapies ineffective and requiring alternative drug regimens.

The correct option is Present in host organs without causing immediate clinical symptoms. In latent syphilis, spirochetes retreat to tissues (like the spleen and lymph nodes). They remain metabolically active and can be detected serologically, but do not produce visible clinical signs.

The correct option is Provides a direct portal of entry and recruits CD4 immune cells to the site. Ulcers disrupt the protective epithelial barrier, giving HIV direct access to the bloodstream. Additionally, the inflammation recruits CD4 T-cells and macrophages (HIV target cells) to the ulcer base.

The correct option is Columnar epithelial cells. N. gonorrhoeae specifically targets and adheres to columnar and transitional epithelium (found in the cervix and urethra). The adult vagina is lined with stratified squamous epithelium, which resists gonococcal attachment.

The correct option is Highly infectious and extremely painful. A primary clinical distinction is that herpes lesions (vesicles and shallow ulcers) are highly infectious and notoriously painful, whereas the syphilitic chancre is typically solitary, infectious, and painless.

The correct option is Execute a corkscrew motility to penetrate viscous tissues. The spiral shape and internal axial filaments give the spirochete unique motility, allowing it to drill into mucous membranes and disseminate quickly into the host's tissues and bloodstream.

The correct option is Macrophages. Macrophages (and dendritic cells) also express the CD4 receptor and CCR5 coreceptor. They are often the first cells infected in mucosal tissues during sexual transmission and act as reservoirs carrying the virus to lymph nodes.

The correct option is Gonorrhea. Neisseria gonorrhoeae are characteristically observed as Gram-negative diplococci phagocytosed by neutrophils in the purulent discharge of an infected patient.

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 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 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 Neisseria gonorrhoeae. This measure specifically prevents ophthalmia neonatorum, a blinding eye infection caused by gonococci acquired during transit through an infected birth canal.

The correct option is Evade the host's acquired immune response. By constantly changing the amino acid sequence of its pili, the bacterium renders previously formed host antibodies useless, allowing it to evade immune clearance and cause repeat infections.