Question 1

When a nurse assess the viral marker and seen antibody against Hb envelope antigen, it indicate?

Accepted Answer

Answer reason: This seroconversion reflects reduced production of e antigen, which correlates with less active replication compared with the HBeAg-positive state. In contrast, “active viral replication” aligns more with the presence of HBeAg and high HBV DNA levels. While infection can still persist, the marker specifically signals a transition toward a lower-replication phase rather than acute infection.

Question 2

Which of the following mode of spread of polio infection is?

Accepted Answer

Answer reason: After entering through the gastrointestinal tract, it replicates in the oropharynx and intestinal mucosa, leading to high stool viral loads that drive community spread. Bloodborne transmission is not the usual route for person-to-person spread, even though brief viremia can occur during infection. Vector transmission is not a mechanism for poliovirus. Droplet spread can occur but is far less important than fecal–oral transmission in typical epidemiology and exam framing.

Question 3

After conducting a rapid urine test on a patient, the nurse informs the physician that she feels the patient should have a urine culture. Why would a nurse want a patient to have a urine culture?

Accepted Answer

Answer reason: It can also provide organism identification and susceptibility results, which a rapid dipstick cannot. Dipstick findings like nitrites, leukocyte esterase, protein, or ketones are screening markers and do not specify the causative organism. hCG testing is for pregnancy screening and is not the purpose of urine culture.

Question 4

Which is a gram-negative bacteria?

Accepted Answer

Answer reason: Gram-negative bacteria have an outer membrane containing lipopolysaccharide and typically stain pink/red on Gram stain. Escherichia coli is a classic gram-negative rod in the Enterobacterales group and a common cause of UTIs and GI infections. In contrast, Staphylococcus and Streptococcus species are gram-positive cocci, and Bacillus species are gram-positive rods, making them incorrect choices. Therefore the only option that matches gram-negative classification is the listed organism.

Question 5

The disease caused by mosquito bite is —?

Accepted Answer

Answer reason: This leads to malaria, characterized by cyclical fevers, chills, anemia, and potential severe complications such as cerebral involvement. The other choices are not mosquito-borne infectious diseases: diabetes is metabolic, asthma is an inflammatory airway disorder, and arthritis is primarily degenerative/autoimmune or infectious via other routes. Therefore the only option that matches a mosquito-bite–transmitted disease is the one associated with vector-borne parasitic infection.

Question 6

Sleeping sickness' is caused by..?

Accepted Answer

Answer reason: The causative organisms (Trypanosoma brucei gambiense/rhodesiense) are spread to humans through the bite of the tsetse fly (Glossina species). This vector association is a classic epidemiology fact used to distinguish it from other insect-borne diseases (e.g., sand fly for leishmaniasis, mosquitoes for malaria/filariasis). Therefore the transmission source asked in the stem aligns with the tsetse fly.

Question 7

Which of the following vector causes scabies?

Accepted Answer

Answer reason: Hominis, which burrows into the stratum corneum and triggers intense pruritus and a hypersensitivity rash. The causative organism is an ectoparasitic mite rather than an insect that transmits disease through biting. Mosquitoes and sandflies are vectors for other infections (e.g., malaria/dengue and leishmaniasis), and lice cause pediculosis, not scabies. Therefore the only option that matches the etiologic agent of scabies is the itch mite.

Question 8

An agent which has the power to kill bacteria is?

Accepted Answer

Answer reason: This contrasts with bacteriostatic agents, which stop bacterial replication but rely on host defenses to clear organisms. Antiseptics and disinfectants describe intended use (on living tissue vs inanimate objects) and may be bactericidal or bacteriostatic depending on the product and concentration. Therefore, the term that directly means “kills bacteria” is the correct choice.

Question 9

Which of the following is a vector of infection?

Accepted Answer

Answer reason: A fly can mechanically transfer microorganisms on its body parts or via regurgitation/feces to food or surfaces, facilitating infection spread. In contrast, contaminated objects like a ball or thermometer are fomites (inanimate vehicles), not vectors. An infected person is a reservoir/source of infection rather than a vector.

Question 10

Mycology is the study of?

Accepted Answer

Answer reason: The prefix “myco-” refers specifically to fungi (e.g., yeasts and molds), including medically important pathogens like Candida and dermatophytes. Protozoa are studied in parasitology/protozoology, fossils in paleontology, and lizards in herpetology, making them incorrect for this term. Knowing these “-ology” roots helps quickly identify organism groups relevant to infection and antifungal therapy.

Question 11

Food poisoning is caused by...?

Accepted Answer

Answer reason: This organism is a common cause of foodborne diarrheal illness via enterotoxigenic and enterohemorrhagic strains, producing rapid-onset watery or bloody diarrhea depending on the strain. The botulism organism more specifically causes neurotoxic foodborne illness with flaccid paralysis rather than typical “food poisoning” diarrhea. Salmonella typhi primarily causes enteric (typhoid) fever, a systemic illness rather than the usual acute food poisoning syndrome.

Question 12

Filariasis is caused by?

Accepted Answer

Answer reason: Among the listed choices, the only helminth category provided is “Tapeworm,” which best matches a worm etiology compared with viral, bacterial, or protozoal causes. Protozoa cause diseases like malaria and amoebiasis rather than lymphatic filariasis. Although the precise organism type is a nematode (not a cestode), this option is the closest correct classification within the given answers.

Question 13

Tetanus is caused by?

Accepted Answer

Answer reason: The clinical syndrome results from tetanospasmin blocking inhibitory neurotransmitter release (GABA and glycine), leading to muscle rigidity and spasms (e.g., trismus, opisthotonos). This mechanism and organism type fit bacterial etiology rather than viral, fungal, or protozoal pathogens. Immunization with tetanus toxoid prevents toxin-mediated disease even if exposure occurs.

Question 14

Rotavirus vaccine is used to prevent which disease?

Accepted Answer

Answer reason: The vaccine targets rotavirus infection and therefore reduces severe gastroenteritis episodes and related hospitalizations. This directly corresponds to prevention of diarrheal illness rather than neurologic disease (polio) or chronic viral syndromes such as HIV/AIDS. Hepatitis vaccines are separate immunizations aimed at hepatotropic viruses, not rotavirus.

Question 15

The disease 'Tetanus' is also known as...?

Accepted Answer

Answer reason: This disinhibition leads to sustained muscle rigidity and painful spasms, classically starting with trismus due to masseter muscle spasm. The hallmark presentation is therefore jaw stiffness and inability to open the mouth. In contrast, shingles is varicella-zoster reactivation, and whooping cough is pertussis with paroxysmal cough, neither causing generalized spasticity. Gangrene refers to tissue necrosis and is not the typical defining clinical synonym for tetanus.

Question 16

Which organism is anaerobic?

Accepted Answer

Answer reason: C. Bacteroides fragilis Obligate anaerobes grow in the absence of oxygen and are classic causes of infections in low-oxygen tissues such as the gut and deep abscesses. This organism is a well-known obligate anaerobic gram-negative rod from normal colonic flora and commonly contributes to intra-abdominal infections. In contrast, one option listed is an obligate aerobe and therefore requires oxygen for growth. The remaining two are facultative anaerobes, meaning they can grow with or without oxygen, so they are not the best single answer.

Question 17

Who is known as "father of antiseptic surgery"?

Accepted Answer

Answer reason: Lister pioneered the clinical use of carbolic acid (phenol) sprays and dressings and promoted antiseptic technique in surgery after germ theory gained acceptance. This directly aligns with the title “father of antiseptic surgery.” A common confusion is with Robert Koch, who advanced bacteriology and postulates but did not establish antiseptic surgical practice.

Question 18

All these are bacterial infections except?

Accepted Answer

Answer reason: Malaria is caused by Plasmodium species, a protozoan parasite transmitted by Anopheles mosquitoes, so it is not a bacterial infection. In contrast, tuberculosis (spelled here as “Tubroluosis”) is caused by Mycobacterium tuberculosis, tetanus by Clostridium tetani, and typhoid by Salmonella Typhi—all bacteria. Recognizing malaria as parasitic also aligns with its treatment using antimalarial agents rather than antibiotics.

Question 19

The handwashing is performed to remove which of the following? (FON)?

Accepted Answer

Answer reason: These organisms are the main source of cross-transmission in healthcare and are effectively reduced by soap-and-water washing or alcohol-based hand rubs. In contrast, resident flora live deeper in the skin and are not fully eliminated by routine handwashing, which is why surgical hand antisepsis uses more intensive methods. Bacterial spores are relatively resistant to alcohol; while soap-and-water can help physically remove them, routine “handwashing” is classically taught as targeting transient organisms rather than reliably eliminating spores.

Question 20

What type of disease is Malaria?

Accepted Answer

Answer reason: The organism invades hepatocytes and then red blood cells, producing cyclical fevers and hemolysis typical of protozoal parasitemia. Viral and bacterial illnesses do not involve an intraerythrocytic parasitic life cycle. Fungal infections are typically due to yeasts or molds and do not match malaria’s vector-borne protozoan pathogenesis.

Question 21

Rabies virus mainly affected?

Accepted Answer

Answer reason: The dominant pathology is encephalitis with progressive neurologic dysfunction (e.g., agitation, hydrophobia, autonomic instability) once the brain is involved. Because the lethal phase is driven by CNS infection rather than primary injury to solid organs, the organ system mainly affected is the brain and spinal cord. Options like kidney or liver may be involved secondarily in critical illness but are not the primary target of rabies infection.

Question 22

A patient is diagnosed with pharyngitis caused by group A streptococcus. The nurse recognizes this infection is commonly known as?

Accepted Answer

Answer reason: This organism can produce exudative tonsillopharyngitis and is clinically important because untreated infection can lead to acute rheumatic fever and post-streptococcal glomerulonephritis. Influenza A is a viral respiratory illness, not a specific label for GAS pharyngitis. COPD and sinus infection describe different disease processes and are not the common name for GAS throat infection.

Question 23

The nurse is assessing a female client with a diagnosis of syphilis. Which of the following would the nurse recognize as an expected finding?

Accepted Answer

Answer reason: This characteristic lesion is an expected finding and is a key discriminator from other causes of genital symptoms. Dysuria and dyspareunia are more typical of urinary tract infection, vulvovaginitis, or cervicitis rather than uncomplicated primary syphilis. Vaginal discharge is more suggestive of infections such as gonorrhea, chlamydia, trichomoniasis, or bacterial vaginosis than syphilis.

Question 24

Acidithiobacillus ferrooxidans is used for the recovery of _____ from ore?

Accepted Answer

Answer reason: This microbial oxidation promotes solubilization of metals—classically from low-grade sulfide ores—enabling hydrometallurgical extraction. In industrial microbiology, it is most commonly associated with recovery of copper from ores (e.g., chalcopyrite) via heap leaching. Other listed choices are either reactants/byproducts of the process (e.g., sulfuric acid) or not the canonical target in standard exam contexts.

Question 25

As cheese ages, it gets?

Accepted Answer

Answer reason: Cheese ripening involves ongoing microbial and enzymatic metabolism of residual lactose and other substrates, with organic acid production and pH shifts being a key biochemical change early in aging. Increased acidity is a common and testable outcome of fermentation-driven maturation, especially in many cultured cheeses. “More whey” is incorrect because whey is largely drained during processing and moisture generally decreases with aging rather than increasing. “More protein” does not occur because protein is broken down into peptides and amino acids during proteolysis rather than accumulating.

Question 26

In the scientific name Enterobacter aerogenes, Enterobacter is the?

Accepted Answer

Answer reason: Binomial nomenclature uses a two-part scientific name in which the first word designates the genus and the second word is the specific epithet (species identifier). This naming convention is standardized in microbiology to group closely related organisms under the same genus based on shared characteristics and phylogeny. In “Enterobacter aerogenes,” the first term therefore represents the genus, while “aerogenes” differentiates the species within that genus. Higher taxonomic ranks like family, order, and kingdom encompass progressively broader groupings and are not used as the first word in the binomial name.

Question 27

Into which group would you place a photosynthetic cell that lacks a nucleus?

Accepted Answer

Answer reason: Photosynthesis can occur in prokaryotes (e.g., cyanobacteria) using internal membrane systems and photosynthetic pigments, even without a true nucleus. The other listed groups (Animalia, Fungi, Plantae, Protista) are eukaryotic and, by definition, have a nucleus. Therefore the organism described fits the bacterial/prokaryotic category rather than any eukaryotic kingdom.

Question 28

Into which group would you place a multicellular heterotroph with chitin cell walls?

Accepted Answer

Answer reason: Being a heterotroph fits fungi because they obtain nutrients by absorption of organic material rather than photosynthesis. Multicellularity is common in fungi (e.g., molds and mushrooms), whereas animals are heterotrophic but lack cell walls, and plants have cellulose-based cell walls and are primarily autotrophic. Bacteria and archaea are prokaryotes and do not match the multicellular eukaryotic profile described.

Question 29

In bacteria, photosynthetic pigments are found in?

Accepted Answer

Answer reason: Prokaryotes lack membrane-bound organelles such as chloroplasts, so bacterial photosynthetic machinery must be located in specialized regions of the cell membrane. In photosynthetic bacteria, pigments (e.g., bacteriochlorophylls and carotenoids) are embedded in membranous infoldings called chromatophores that support light capture and electron transport. Cytoplasm and ribosomes do not provide the organized membrane surface needed for photophosphorylation. Mesosomes are not accepted as true functional organelles for photosynthesis and are largely considered artifacts of preparation.

Question 30

Which one of the following organisms has a cell wall?

Accepted Answer

Answer reason: In contrast, animal cells lack cell walls and rely on a plasma membrane and extracellular matrix for structural integrity. Protoplasts and L-forms are wall-deficient variants of bacteria created by enzymatic removal or altered growth conditions, respectively. Mycoplasmas are naturally cell wall–deficient bacteria, which is why they are intrinsically resistant to beta-lactam antibiotics that target peptidoglycan synthesis.

Question 31

In a hypertonic solution, a bacterial cell will typically?

Accepted Answer

Answer reason: Water moves by osmosis from lower solute concentration to higher solute concentration, so a hypertonic environment pulls water out of the cell. Loss of intracellular water causes the cytoplasmic membrane to shrink away from the rigid cell wall, producing plasmolysis in bacteria. This leads to cellular dehydration and growth inhibition rather than rupture. Lysis/bursting is characteristic of hypotonic conditions when water influx increases internal pressure beyond structural limits.

Question 32

Which of the following is NOT a zoonosis?

Accepted Answer

Answer reason: Hantavirus is classically acquired from rodent excreta, anthrax is associated with livestock/animal products, brucellosis is linked to unpasteurized dairy or animal exposure, and tularemia is associated with rabbits/ticks/deer flies. Puerperal sepsis is postpartum genital tract infection typically caused by human flora or healthcare-associated pathogens and is not defined by animal-to-human transmission. Therefore it is the only option that is not a zoonotic disease.

Question 33

Which of the following is directly involved in the initiation of dental caries?

Accepted Answer

Answer reason: This acid-driven demineralization is the immediate initiating event in cavity formation. Salivary defenses like lysozyme and protective fluids tend to inhibit bacterial growth rather than start decay, and dentin is a tooth structure affected after enamel breakdown. Sucrose is an important substrate that promotes plaque formation and acid production, but the direct damaging agent that initiates demineralization is the acid.

Question 34

Dental plaque is an example of?

Accepted Answer

Answer reason: Dental plaque is a structured community of microorganisms adherent to the tooth surface and embedded in a self-produced extracellular matrix, which defines a biofilm. This biofilm architecture increases bacterial persistence and resistance to mechanical removal and antimicrobial agents compared with free-floating (planktonic) bacteria. A pellicle is an acellular protein film that forms first on enamel and serves as a substrate for bacterial attachment, but it is not itself plaque. Gingivitis is an inflammatory condition of the gums caused by plaque accumulation rather than the plaque material itself.

Question 35

All of the following microorganisms can directly cause meningitis EXCEPT?

Accepted Answer

Answer reason: Meningitis is an inflammation of the meninges caused by infectious agents that can invade the CNS, most commonly bacteria and viruses, and also fungi and some protozoa. Mosquitoes are vectors that may transmit pathogens (e.g., arboviruses), but they are not themselves microorganisms and do not directly infect the meninges. The question asks for the exception to “microorganisms” that directly cause meningitis, making the vector the best choice. A common trap is to confuse a vector with the organism it transmits; only the transmitted pathogen can directly cause meningitis.

Question 36

Which of the following is NOT an intracellular parasite?

Accepted Answer

Answer reason: Chlamydophila and Coxiella are classic obligate intracellular bacteria, and respiratory viruses such as influenza virus and RSV require intracellular replication. Coccidioides is a dimorphic fungus that can be grown in culture and is not obligately intracellular, even though it forms spherules in tissue. Therefore it is the best choice for an organism that is not an intracellular parasite among the options.

Question 37

Which of the following is NOT a typical symptom of influenza?

Accepted Answer

Answer reason: Typical manifestations include abrupt fever, chills, headache, and diffuse myalgias due to cytokine-mediated inflammation. Gastrointestinal symptoms are not the usual primary presentation in uncomplicated influenza and, when present, are less characteristic compared with these systemic/respiratory features. A common distractor is fever or myalgias, which are hallmark findings and therefore expected in most cases.

Question 38

Which of the following is used to treat sporotrichosis?

Accepted Answer

Answer reason: The other options target different pathogen classes: penicillin and sulfonamides are antibacterials, while acyclovir and trifluridine are antivirals used for herpesvirus infections. Because the question asks specifically for therapy for sporotrichosis, the antifungal-appropriate historical standard among the choices is potassium iodide. This selection matches the traditional board-style association for sporotrichosis treatment.

Question 39

Which of the following is used to treat candidiasis of the skin or mucous membranes?

Accepted Answer

Answer reason: Azole antifungals inhibit ergosterol synthesis in the fungal cell membrane, making them effective for superficial Candida infections of skin and mucous membranes (e.g., cutaneous candidiasis, vulvovaginal candidiasis, oral thrush when used appropriately). Penicillin and sulfonamides are antibacterials and do not eradicate fungal organisms. Trifluridine and acyclovir are antivirals used for herpesvirus infections rather than Candida.

Question 40

Warts are caused by?

Accepted Answer

Answer reason: Warts are benign epithelial proliferations caused by infection of keratinocytes with human papillomavirus (HPV). HPV induces hyperplasia and hyperkeratosis in the epidermis, producing the characteristic verrucous lesions. Poxviruses more typically cause molluscum contagiosum (umbilicated papules), not common warts. Herpesviruses cause vesicular lesions, and Staphylococcus aureus causes bacterial skin infections such as impetigo or abscesses rather than warts.

Question 41

Koplik spots are a diagnostic indicator of?

Accepted Answer

Answer reason: Koplik spots are an enanthem classically seen on the buccal mucosa and are considered pathognomonic for rubeola infection. They typically appear in the prodromal phase with fever, cough, coryza, and conjunctivitis before the maculopapular rash develops. This makes them a high-yield diagnostic clue that distinguishes rubeola from other viral exanthems. For example, rubella can cause a rash and lymphadenopathy but does not produce Koplik spots.

Question 42

All of the following are transmitted via the respiratory route EXCEPT?

Accepted Answer

Answer reason: Respiratory-route transmission typically involves inhalation of droplets or airborne particles, which is characteristic of several viral exanthems. Smallpox, chickenpox (varicella), rubella, and measles spread primarily via respiratory secretions/airborne spread (often with high contagiousness for measles/varicella). Tinea is a dermatophyte fungal infection that is usually acquired through direct skin-to-skin contact, contact with contaminated fomites (towels, floors), or infected animals rather than inhalation. Therefore it is the exception among the listed diseases.

Question 43

Scabies is a skin disease caused by a?

Accepted Answer

Answer reason: Scabies is caused by an ectoparasite that burrows into the stratum corneum, producing intense pruritus and characteristic linear burrows. The causative organism is Sarcoptes scabiei var. hominis, which is an arthropod rather than a bacterium or virus. Protozoa typically cause systemic or GI/genitourinary infections, not burrowing skin infestations. Prions and slow viruses are associated with neurodegenerative diseases and do not produce this type of contagious skin infestation.

Question 44

Staphylococcus aureus is responsible for all of the following EXCEPT?

Accepted Answer

Answer reason: Staphylococcal skin disease classically causes acute, purulent infections of hair follicles and associated glands, leading to localized abscesses and cellulitis. Pimples, boils (furuncles), and carbuncles are common manifestations of follicular infection/abscess formation due to this organism, and styes (hordeola) are typically caused by infection of eyelid glands by the same pathogen. In contrast, classic acne vulgaris is primarily driven by follicular plugging and inflammation associated with Cutibacterium (Propionibacterium) acnes rather than being a typical primary staphylococcal disease. While secondary infection can occur, the tested “EXCEPT” points to acne’s usual causative organism differing from staphylococcal disease patterns.

Question 45

Exfoliative toxin is responsible for?

Accepted Answer

Answer reason: Staphylococcus aureus produces exfoliative toxins (ETA/ETB) that cleave desmoglein-1 in the stratum granulosum, causing superficial epidermal splitting. This mechanism leads to diffuse erythema, flaccid bullae, and widespread desquamation characteristic of staphylococcal scalded skin syndrome. Otitis externa is most commonly due to Pseudomonas aeruginosa or S. aureus but is not toxin-mediated in this way. Fever blisters are due to HSV, and thrush is due to Candida, so they do not match the toxin-pathogenesis pairing.

Question 46

Scabies is transmitted by?

Accepted Answer

Answer reason: Scabies is caused by Sarcoptes scabiei and spreads primarily through prolonged direct skin-to-skin contact, with indirect spread possible via contaminated items such as bedding, towels, and clothing. These contaminated objects function as fomites and can transmit mites, particularly in crowded settings or when items are shared soon after use. Transmission is not foodborne or waterborne, and it is not acquired from soil exposure. It is also not spread by respiratory secretions because the organism is an ectoparasite living on/within the superficial skin, not a respiratory pathogen.

Question 47

Buruli ulcer is caused by?

Accepted Answer

Answer reason: Buruli ulcer is caused by Mycobacterium ulcerans, which is a mycobacterium with a lipid-rich cell wall that retains acid-fast staining. This organism produces mycolactone toxin, leading to painless necrotizing skin ulcers, a presentation characteristic of mycobacterial disease rather than viral or fungal infections. While many bacteria are classified by Gram stain, mycobacteria do not reliably Gram-stain due to their waxy cell wall and are instead identified as acid-fast. Mites cause parasitic infestations (e.g., scabies) with pruritus rather than progressive undermined ulcers.

Question 48

Staphylococcus saprophyticus causes?

Accepted Answer

Answer reason: Staphylococcus saprophyticus is a common cause of uncomplicated lower urinary tract infection, especially in sexually active young women, and it characteristically produces bladder infection symptoms (dysuria, frequency, urgency). This organism adheres well to uroepithelium and is a recognized “second most common” bacterial cause of community-acquired cystitis after E. coli. Pyelonephritis is an upper-tract infection more often caused by ascending gram-negative enteric bacteria, and S. saprophyticus is less typical as a primary cause. Vaginitis is usually due to Candida, Trichomonas, or bacterial vaginosis organisms, while gonorrhea and syphilis are caused by Neisseria gonorrhoeae and Treponema pallidum, respectively.

Question 49

The most common NGU in the United States is treated with?

Accepted Answer

Answer reason: Nongonococcal urethritis is most commonly caused by Chlamydia trachomatis in the U.S., and first-line therapy targets intracellular organisms with tetracyclines or macrolides. This option directly treats chlamydial NGU and is a standard empiric choice when gonorrhea has been excluded or after appropriate dual-coverage decisions. Cephalosporins are aimed at Neisseria gonorrhoeae rather than typical NGU causes, so they do not best match the stem. Acyclovir and AZT treat viral infections (HSV and HIV), not the common bacterial etiology of NGU.

Question 50

Which of the following recurs at the initial site of infection?

Accepted Answer

Answer reason: Reactivation typically produces recurrent vesicular lesions in the same anatomic distribution as the initial inoculation site because the virus travels back down the same peripheral nerves. In contrast, syphilis progresses through stages with systemic dissemination rather than true localized recurrence at the original lesion site, and gonorrhea/chancroid/LGV are bacterial infections that more commonly cause reinfection or ongoing infection rather than classic viral latency with periodic local recurrences. Therefore the condition characterized by recurrence at the initial site is the one with latent neurotropic behavior.

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