Question 1

A male client is asking the nurse a question regarding the Mantoux test for tuberculosis. The nurse should base her response on the fact that the?

Accepted Answer

Answer reason: The Mantoux (PPD) test measures delayed-type (type IV) hypersensitivity to TB antigens and reflects immune sensitization rather than current disease activity. A positive result indicates prior exposure, latent infection, or prior BCG vaccination, so it cannot distinguish latent from active tuberculosis. Interpretation is based on the size of induration (not redness) measured at 48–72 hours, and a wheal immediately after injection only confirms proper intradermal placement. Active TB requires further evaluation such as symptoms review, chest imaging, and microbiologic testing (e.g., sputum AFB/NAAT).

Question 2

A child is being discharged to home with a diagnosis of ringworm. Discharge instructions should include the information that?

Accepted Answer

Answer reason: Ringworm (tinea) is a superficial dermatophyte infection, meaning it is caused by fungi rather than worms, viruses, or bacteria. Dermatophytes spread through direct skin-to-skin contact and indirectly via contaminated items (combs, hats, towels, bedding) and sometimes from infected pets, so transmission person-to-person is a key discharge teaching point. This also supports counseling on hygiene, not sharing personal items, and completing antifungal therapy to reduce spread and recurrence. Options claiming it is a worm or that it cannot be transmitted are incorrect and would lead to inadequate infection control at home.

Question 3

Which one of the following is a DNA Virus?

Accepted Answer

Answer reason: Hepatitis B virus belongs to the Hepadnaviridae family and has a partially double-stranded circular DNA genome with reverse transcription in its replication cycle. In contrast, Hepatitis A (picornavirus), Hepatitis C (flavivirus), and Hepatitis D (defective deltavirus) are RNA viruses. Therefore the only DNA virus listed is the one associated with hepadnaviruses.

Question 4

Which is a characteristic of person-to-person propagated epidemics?

Accepted Answer

Answer reason: Person-to-person (propagated) epidemics spread through sequential transmission between individuals, producing a progressive rise in incidence over multiple incubation periods. This creates a gradual buildup of cases and often successive waves rather than an abrupt spike. In contrast, common-vehicle outbreaks (e.g., contaminated food or water) tend to show a rapid, sharp increase in cases clustered in time. Vector transmission is not required for propagated spread because direct or indirect human-to-human transmission is sufficient.

Question 5

Among children aged 2 months to 3 years, the most prevalent form of meningitis is caused by which microorganism?

Accepted Answer

Answer reason: It commonly colonizes the nasopharynx and can invade the bloodstream and meninges, especially in infants/toddlers. Haemophilus influenzae type b used to be a leading cause in this age group but is now much less prevalent where Hib vaccination is routine. Neisseria meningitidis becomes relatively more prominent in older children, adolescents, and young adults rather than being the single most prevalent cause in 2 months to 3 years.

Question 6

Human beings are the major reservoir of malaria. Which of the following strategies in malaria control is based on this fact?

Accepted Answer

Answer reason: Zooprophylaxis uses domestic animals as alternative blood-meal hosts placed near human habitations to attract vectors away from people, thereby interrupting the human-to-mosquito-to-human cycle. In contrast, stream seeding/clearing and destroying breeding places primarily target mosquito larvae and breeding sites and are not specifically based on the reservoir being humans. Therefore the strategy that is conceptually anchored to the human reservoir and human-vector contact is the use of zooprophylaxis.

Question 7

The use of larvivorous fish in malaria control is the basis for which strategy of malaria control?

Accepted Answer

Answer reason:  Biological control of malaria targets the larval stage of Anopheles mosquitoes by introducing natural predators into water sources. Larvivorous fish (e.g., Gambusia) are released into streams/ponds to consume mosquito larvae and reduce vector density at the aquatic habitat. This intervention is specifically termed “stream seeding,” meaning stocking water bodies with larva-eating fish. In contrast, clearing streams or destroying breeding places refers to environmental modification (drainage, filling, vegetation removal) rather than adding a biocontrol organism, and zooprophylaxis involves diverting mosquitoes to animals, not larval predation.

Question 8

In the Philippines, which specie of schistosoma is endemic in certain regions?

Accepted Answer

Answer reason: S. japonicum Schistosoma species have distinct geographic distributions that determine endemicity. In the Philippines, the dominant endemic species causing intestinal schistosomiasis is associated with zoonotic reservoirs and is widely recognized in standard parasitology epidemiology. This matches the species known to be prevalent in parts of East and Southeast Asia, including the Philippines. A common distractor is the species more typical of Africa and parts of South America rather than the Philippines, making it less consistent with the stem.

Question 9

Mosquito-borne diseases are prevented mostly with the use of mosquito control measures. Which of the following is NOT appropriate for malaria control?

Accepted Answer

Answer reason:  Malaria prevention relies on reducing human–mosquito contact and lowering vector populations, especially for night-biting Anopheles mosquitoes. Insecticide-treated bed nets directly block bites and kill mosquitoes that contact the net, making them a core, evidence-based control measure. Larval control (e.g., larvivorous fish) and destruction of breeding sites reduce mosquito density and transmission risk at the community level. Repellent soaps with herbal additives have unreliable, short-lived repellency and are not considered an effective malaria control strategy compared with proven vector-control interventions.

Question 10

Among the following diseases, which is airborne?

Accepted Answer

Answer reason:  Airborne transmission involves infectious droplet nuclei/aerosols that remain suspended and can travel on air currents; classic pathogens include measles and varicella. Measles (rubeola) is among the most contagious infections and requires airborne isolation with an N95/respirator and negative-pressure room when available. By contrast, viral conjunctivitis is typically spread by direct contact and contaminated fomites, and diphtheria is primarily droplet/contact spread (with contact precautions for cutaneous disease). Poliomyelitis spreads mainly via the fecal–oral route, so standard/contact precautions focused on enteric transmission are most relevant.

Question 11

All are soil mediated infections, except?

Accepted Answer

Answer reason: Whipworm (Trichuris) and roundworm (Ascaris) are classic fecal–oral infections from soil-contaminated hands/food, and hookworm larvae penetrate skin from contaminated ground. In contrast, most human tapeworm infections are food-borne, acquired by eating undercooked beef/pork/fish containing larval cysts (or by ingesting eggs in specific scenarios like Taenia solium leading to cysticercosis), not primarily via soil exposure. Therefore the option that is not soil mediated is the one associated mainly with ingestion of larval forms in meat or fish.

Question 12

The vaccination was first performed by?

Accepted Answer

Answer reason: The first widely recognized modern vaccination was the smallpox vaccine, developed from cowpox inoculation, establishing the core principle of cross-protection between related pathogens. This pioneering work predates later vaccine advances such as inactivated poliovirus vaccine development and laboratory-attenuated vaccine work. The other options are associated with later milestones in microbiology and epidemiology rather than the first performance of vaccination.

Question 13

In the large intestine, vitamin K is formed by the activity of ?

Accepted Answer

Answer reason: This is best described as symbiosis/commensalism, not parasitism, because the host is not harmed. The terms “facultative” and “obligate” primarily describe oxygen requirements rather than the ecological relationship responsible for vitamin K contribution. Therefore, the option identifying the beneficial host–microbe relationship is the most accurate.

Question 14

BCG vaccine is given to...?

Accepted Answer

Answer reason: g., miliary TB and TB meningitis). The other listed diseases have different vaccines: tetanus is prevented with tetanus toxoid-containing vaccines, and polio is prevented with OPV/IPV. While BCG has a therapeutic role in certain cancers (notably intravesical therapy for superficial bladder cancer), its standard indication as a vaccine is prevention of tuberculosis. Therefore the best single answer is the disease for which it is routinely administered as an immunization.

Question 15

When teaching adolescents about sexually transmitted diseases, what should the nurse emphasize that is the most common infection?

Accepted Answer

Answer reason: It is frequently asymptomatic, so many infections go undiagnosed and continue to spread without screening and treatment. This epidemiology makes it the key infection to emphasize in adolescent sexual health education, alongside prevention and routine testing. Gonorrhea is also common but has a lower overall incidence, while herpes and HIV are important infections yet are not the most common overall.

Question 16

A child and his family were exposed to Mycobacterium tuberculosis about 2 months ago, to confirm the presence or absence of an infection, it is most important for all family members to have a?

Accepted Answer

Answer reason: Since this family was exposed about 2 months ago, testing now can confirm infection status even if individuals are asymptomatic. Chest x-ray helps evaluate for active pulmonary disease but does not reliably detect latent infection. Sputum culture is reserved for suspected active pulmonary TB and is not appropriate as the most important initial test for all exposed family members.

Question 17

The recent increase in the reported cases of active tuberculosis (TB) in the United States is attributed to which factor?

Accepted Answer

Answer reason: TB reactivation and progression to active disease are strongly driven by impaired cell-mediated immunity. HIV infection markedly increases the risk of latent TB reactivation and susceptibility to new TB infection, leading to higher rates of active TB in the population. This mechanism also contributes to more severe disease and ongoing transmission when diagnosis is delayed. While homelessness and immigration can contribute to exposure and barriers to care, immunosuppression from HIV is a key epidemiologic factor linked to the resurgence of active TB.

Question 18

MEASLES IS OTHERWISE CALLED AS?

Accepted Answer

Answer reason: Rubella is a different viral illness (German measles) with distinct clinical implications such as congenital rubella syndrome. Varicella refers to chickenpox caused by varicella-zoster virus, and smallpox is caused by variola virus and is eradicated. Therefore, the only synonym that correctly matches measles is the term used for measles itself.

Question 19

CLUE CELLS ARE SEEN IN?

Accepted Answer

Answer reason: This finding is a key Amsel criterion and is strongly associated with bacterial vaginosis rather than inflammatory STI causes. In candidiasis, microscopy more typically shows budding yeast/pseudohyphae; in trichomoniasis, motile trichomonads are seen; and gonorrhoea is identified by intracellular gram-negative diplococci. Therefore the condition most directly linked to clue cells is bacterial vaginosis.

Question 20

Widal test is performed-?

Accepted Answer

Answer reason: This aligns with diagnosing enteric (typhoid) fever, especially in settings where culture is not readily available. It is not a test for HIV/AIDS, which is identified by antigen/antibody assays and confirmatory nucleic acid testing. Diarrhea or dysentery have broad infectious and noninfectious causes and are evaluated with stool studies and cultures rather than this specific Salmonella antibody test.

Question 21

Chain of spreading of malaria is?

Accepted Answer

Answer reason: An infected human serves as the reservoir with circulating gametocytes, which are ingested by the mosquito during a blood meal and develop into infectious sporozoites. The mosquito then inoculates sporozoites into another human host during a subsequent bite, completing the human–vector–human chain. Options involving birds or pigs describe other zoonotic cycles and do not reflect the obligatory Anopheles-mediated transmission of human malaria.

Question 22

Leading cause of diarrheal disease in:

Accepted Answer

Answer reason: It infects and damages small-intestinal enterocytes, causing malabsorption and secretory diarrhea that can lead to significant dehydration. While enterotoxigenic E. coli is a common cause of traveler’s diarrhea and Campylobacter/Salmonella are important causes of bacterial gastroenteritis, they are not typically the leading overall cause of diarrheal disease in the general pediatric population. The option given best matches the classic “leading cause” teaching point for diarrheal disease.

Question 23

All of the following are Anthropozoonotic diseases except?

Accepted Answer

Answer reason: Plague is classically a rodent-associated infection transmitted via fleas, rabies is transmitted from infected mammals through bites/saliva, and hydatid disease results from Echinococcus cycles involving dogs and livestock with humans as accidental intermediate hosts. Dracunculosis (Guinea worm disease) is acquired by drinking water containing infected copepods and does not require an animal reservoir for human infection in the typical transmission cycle, so it is not an anthropozoonosis. This makes it the best exception among the listed diseases.

Question 24

'Tetanus' disease is also known as?

Accepted Answer

Answer reason: This leads to sustained muscle rigidity and painful spasms, classically starting with trismus, giving the common name “lockjaw.” The other choices refer to different conditions: shingles is reactivation of varicella-zoster virus, whooping cough is Bordetella pertussis infection, and gangrene is tissue necrosis often related to vascular compromise or certain bacterial infections. The hallmark early sign linking tetanus to its nickname is inability to open the mouth due to masseter spasm.

Question 25

Rod shaped bacteria are known as?

Accepted Answer

Answer reason: Cocci are spherical, while comma-shaped bacteria are classically described as vibrios, making those distractors incorrect. “Pleomorphic” refers to variable shapes rather than a specific rod morphology. Therefore, the rod-shaped category is best matched by the bacilli designation.

Question 26

Which of the following pairs of pathogenic microbe and infectious disease is correct?

Accepted Answer

Answer reason: Tuberculosis is caused by Mycobacterium tuberculosis, an acid-fast bacterium, making this pairing correct. Influenza is caused by influenza viruses (not fungi), and chickenpox is caused by varicella-zoster virus (not protozoa). Syphilis is caused by Treponema pallidum, a spirochete bacterium, not a virus, which rules out that option.

Question 27

Live attenuated vaccines are?

Accepted Answer

Answer reason: OPV (oral polio vaccine) is a classic live attenuated vaccine (Sabin strains) that replicates in the gut and induces intestinal IgA in addition to serum antibodies. Tetanus toxoid is an inactivated toxin (toxoid) vaccine, not live. Chickenpox vaccine is also live attenuated, but since this is a single-best-answer item, OPV is the most unambiguous classic example among the listed choices.

Question 28

Bacterial structure involved in respiration is?

Accepted Answer

Answer reason: Mesosomes are classically described as infoldings of the bacterial plasma membrane that increase membrane surface area and are associated with respiratory enzyme systems in many exam frameworks. Ribosomes perform protein synthesis, pili mainly mediate adhesion/conjugation, and flagella provide motility rather than energy generation. Therefore the structure linked to respiration in standard microbiology MCQs is the membrane infolding termed mesosome.

Question 29

Autoclaving is an example of ..?

Accepted Answer

Answer reason: This is classified as moist heat sterilization (e.g., 121°C at 15 psi for a set time) rather than dry heat, which relies on hot air and requires higher temperatures/longer exposure. Chemical agents are disinfectants/sterilants used when heat is unsuitable, not the mechanism of an autoclave. “Biological agents” is not a standard sterilization method category for autoclaving.

Question 30

Negri bodies are found in cells infected with?

Accepted Answer

Answer reason: They are classically seen in Purkinje cells of the cerebellum and hippocampal pyramidal neurons on histopathology. This finding is a high-yield association used to identify rabies infection in tissue. Other listed viruses have different hallmark inclusions (e.g., poxviruses have Guarnieri bodies; herpesviruses have Cowdry type A inclusions), making them less consistent with Negri bodies.

Question 31

What is the most successful and most widely used 'travel' vaccine for international visitors?

Accepted Answer

Answer reason: Yellow fever vaccine is one of the most established travel vaccines and is mandated by many countries for travelers arriving from risk areas, which drives very broad use among international visitors. It is a live-attenuated vaccine with high seroconversion and durable immunity in most recipients, supporting the idea of being “most successful.” In contrast, influenza and MMR are routine immunizations rather than classic entry-linked travel requirements, and rabies vaccination is typically limited to higher-risk exposures or itineraries rather than the general traveling population.

Question 32

OPV/Sabin Is live attenuated vaccine use in polio is?

Accepted Answer

Answer reason: OPV (Sabin) contains live attenuated polioviruses and therefore requires strict cold-chain storage to maintain infectivity. Heat exposure inactivates the vaccine, reducing immunogenicity and leading to vaccine failure. “Cold sensitive” is a more typical concern for some adjuvanted inactivated vaccines that can be damaged by freezing, not for OPV’s primary vulnerability.

Question 33

Confirmatory test use to detect typhoid fever is?

Accepted Answer

Answer reason: Stool and urine cultures can recover the organism later in the illness and are also useful for detecting shedding/carriage, supporting definitive diagnosis when positive. Serologic tests like Widal have significant limitations (baseline antibodies, cross-reactivity, variable cutoffs) and are not considered confirmatory. Rapid antibody assays (e.g., Typhidot, Tubex) may aid screening but lack the specificity required for definitive confirmation compared with culture.

Question 34

Rice water stool is a typical finding in cases of?

Accepted Answer

Answer reason: The stool appears watery with flecks of mucus and little to no blood or fecal material, matching the described finding. This leads to rapid dehydration, hypovolemia, and electrolyte derangements if not treated with aggressive oral/IV rehydration. In contrast, amoebiasis and ulcerative colitis more typically produce inflammatory diarrhea with blood and mucus, while typhoid is associated with systemic febrile illness and may cause “pea-soup” diarrhea rather than rice-water stool.

Question 35

As a condition of employment, all health care personnel at the hospital must have a tuberculin skin test on an annual basis. What does the tuberculin skin test reveal?

Accepted Answer

Answer reason: A positive test supports that the person has been infected at some point, but it cannot distinguish latent infection from active disease. Determining active tuberculosis requires clinical assessment plus diagnostics such as chest imaging and sputum testing. Therefore, it reveals prior infection rather than current contagiousness or general susceptibility.

Question 36

Vaccine for diphtheria

Accepted Answer

Answer reason: The DPT vaccine contains diphtheria toxoid along with pertussis and tetanus components, providing protection against diphtheria as part of routine childhood immunization. TT contains tetanus toxoid only and does not protect against diphtheria. BCG targets tuberculosis and OPV targets poliovirus, so neither addresses diphtheria prevention.

Question 37

Oral polio vaccine is also known as?

Accepted Answer

Answer reason: In contrast, the Salk vaccine refers to the inactivated polio vaccine (IPV) administered by injection. “Pentavalent” is a combination vaccine term and is not a synonym for OPV. Therefore the best match for oral polio vaccine is the eponym associated with the live oral formulation.

Question 38

Tubes and catheters are disinfected with..?

Accepted Answer

Answer reason: Glutaraldehyde at 2% is a classic high-level disinfectant that is effective against vegetative bacteria, mycobacteria, fungi, and many viruses, and with adequate contact time can be sporicidal. Hypochlorite is mainly used for environmental surfaces and can be corrosive or damaging to some device materials, making it less appropriate for delicate tubing. Formalin is primarily a fixative/sterilant with significant toxicity and is not the routine standard for disinfecting such devices in clinical practice.

Question 39

Parenteral polio vaccine is also known as?

Accepted Answer

Answer reason: IPV was developed by Jonas Salk and is therefore commonly called the Salk vaccine. In contrast, the Sabin vaccine is the live attenuated oral polio vaccine (OPV), not parenteral. The other options are unrelated to polio vaccine nomenclature.

Question 40

An agent which kills pathogenic bacteria is called?

Accepted Answer

Answer reason: A disinfectant is the agent that performs this kill effect, distinguishing it from techniques or states like asepsis. A bacteriostat only inhibits bacterial growth rather than killing organisms. A fomite is a contaminated object that can transmit pathogens, not a killing agent.

Question 41

Who is the father of microbiology?

Accepted Answer

Answer reason: He performed decisive work disproving spontaneous generation and demonstrated that microorganisms drive fermentation and spoilage, anchoring modern microbiology. He also advanced vaccination concepts (e.g., attenuation) and pasteurization, directly shaping microbial science and public health practice. While Robert Koch is central for linking specific pathogens to specific diseases (Koch’s postulates), the broader title in many curricula is most commonly attributed to Pasteur.

Question 42

A 35 year-old client is admitted to the emergency department with symptoms of a cough for three weeks, night sweats, and shortness of breath. Suspecting tuberculosis, which test would confirm active tuberculosis in this client?

Accepted Answer

Answer reason: Culture (often alongside smear/NAAT) establishes active disease by demonstrating viable organisms and also allows drug-susceptibility testing. A tuberculin skin test indicates prior sensitization/latent infection and cannot distinguish active disease. A chest X-ray can support suspicion (e.g., cavitary lesions) but is not definitive for microbiologic confirmation.

Question 43

For indirect BCG which administer, which test should be done prior to vaccination?

Accepted Answer

Answer reason: The Mantoux test (tuberculin skin test using PPD) is the standard pre-vaccination screening method to identify existing sensitization to Mycobacterium tuberculosis. If a person has evidence of TB infection or suspected active TB, they should be evaluated and treated rather than vaccinated. Sputum testing is used when active pulmonary TB is suspected, not as a routine prerequisite for vaccination in asymptomatic screening.

Question 44

"German measles" is ..?

Accepted Answer

Answer reason: This name distinction matters because rubeola is measles caused by a paramyxovirus and is generally more severe with higher fever and complications. Mumps is also a paramyxovirus illness characterized by parotitis, and pertussis is a bacterial respiratory infection (Bordetella pertussis) with paroxysmal cough. Therefore the term “German measles” correctly maps to rubella.

Question 45

Scarlet fever is caused by?

Accepted Answer

Answer reason: S. Pyogenes Scarlet fever is caused by Group A beta-hemolytic streptococci that produce erythrogenic (pyrogenic) exotoxins leading to the characteristic sandpaper rash and strawberry tongue after streptococcal pharyngitis. Streptococcus pyogenes is the classic organism responsible and the diagnosis is tied to toxin-mediated disease rather than invasive bacteremia. Neisseria gonorrhoeae and Neisseria meningitidis cause genitourinary infection and meningococcemia/meningitis respectively, not the scarlatiniform rash following strep throat. Salmonella typhi causes enteric (typhoid) fever with systemic gastrointestinal illness, not toxin-mediated pharyngitis with rash.

Question 46

Sharp instruments should not be sterilized by..?

Accepted Answer

Answer reason: Because sharp instruments are “critical items” that must be truly sterile before use on sterile tissue, a method with sporicidal capability is required. Dry heat sterilization in a hot air oven (at validated time/temperature) is an accepted sterilization method for metal instruments, whereas boiling is best considered disinfection only. Antiseptic solutions are for use on living tissue and do not ensure sterility of instruments, but among the listed methods, boiling is the classic incorrect practice when asked specifically about sterilizing instruments.

Question 47

Negri bodies are found in cells infected with ?

Accepted Answer

Answer reason: This finding is classically identified in Purkinje cells of the cerebellum and hippocampal pyramidal neurons on histopathology. Poxviruses (e.g., vaccinia, fowlpox) instead form different cytoplasmic inclusions (e.g., Guarnieri or Bollinger bodies) rather than Negri bodies. Paramyxoviruses are associated with other inclusions (e.g., Warthin-Finkeldey giant cells in measles), not Negri bodies.

Question 48

Diagnostic test used for scarlet fever is?

Accepted Answer

Answer reason: The Dick test involves intradermal injection of erythrogenic toxin, with a local erythematous reaction indicating susceptibility and supporting the diagnosis historically. In contrast, the Schick test is for diphtheria toxin susceptibility, the Mantoux test screens for tuberculosis, and the Widal test supports enteric (typhoid) fever diagnosis. Therefore, the toxin-based test classically associated with scarlet fever is the Dick test.

Question 49

Who is known as "father of bacteriology"?

Accepted Answer

Answer reason: He is credited with constructing powerful single-lens microscopes and describing “animalcules,” providing the earliest documented observations of bacteria. This contribution established the observational basis for microbiology/bacteriology long before germ theory was formalized. A common distractor is Robert Koch, who is more specifically associated with modern bacteriology through Koch’s postulates and identification of specific pathogens rather than the initial discovery/observation of bacteria.

Question 50

Widal test is used for susceptibility of?

Accepted Answer

Answer reason: This directly links it to enteric (typhoid) fever rather than parasitic, viral, or non-Salmonella bacterial diseases. Malaria is diagnosed primarily by peripheral smear or rapid antigen tests, not agglutination antibodies. Cholera diagnosis is typically by stool culture/rapid tests for Vibrio cholerae, and yellow fever is evaluated with viral serology/PCR, making them mismatched to what Widal measures.

Train with a large NCLEX question bank and jump into a full exam-style simulator

Microbiology NCLEX Practice Test

Continue Learning