Question 1

Vaccination against mumps can prevent which condition?

Accepted Answer

Answer reason: Mumps infection can cause orchitis in postpubertal males; MMR vaccination prevents mumps and thus prevents mumps-associated orchitis. The other options are not prevented by mumps vaccination.

Question 2

Which of the following bacteria can cause peptic ulcer?

Accepted Answer

Answer reason: Pylori colonizes the gastric mucosa, produces urease, and causes chronic gastritis leading to peptic ulcer disease; the other listed bacteria are not typical causes.

Question 3

Which test is used to detect HIV?

Accepted Answer

Answer reason: PCR detects HIV RNA and ELISA detects HIV antigen/antibodies; Widal is for typhoid fever.

Question 4

Which are the biological agents?

Accepted Answer

Answer reason: Bacteria, viruses, and fungi are all categories of biological agents capable of causing disease.

Question 5

Which disease is also known as Hansen's disease?

Accepted Answer

Answer reason: Hansen's disease is the formal name for leprosy caused by Mycobacterium leprae.

Question 6

Sleeping sickness in man is caused by which organism?

Accepted Answer

Answer reason: African sleeping sickness is caused by Trypanosoma brucei; the other options cause malaria (Plasmodium), amebiasis (Entamoeba), and giardiasis (Giardia).

Question 7

What is the causative organism of chickenpox?

Accepted Answer

Answer reason: Chickenpox is caused by varicella-zoster virus (HHV-3). Rubella is German measles, paramyxovirus causes measles, and herpes zoster is the reactivation manifestation of VZV.

Question 8

A client is diagnosed with AIDS. The nurse recognizes that an opportunistic infection is present when the oral cavity is examined and white plagues are discovered on the mucosa. What does this finding most likely represent?

Accepted Answer

Answer reason: White plaques in the oral mucosa of a patient with AIDS most commonly indicate oral thrush caused by Candida albicans. CMV typically causes retinitis or ulcers, histoplasmosis is a systemic fungal infection, and HPV causes warts, not white oral plaques.

Question 9

The Widal test is used for the diagnosis of which disease?

Accepted Answer

Answer reason: Widal is a serological agglutination test detecting antibodies to Salmonella typhi/paratyphi O and H antigens, used for typhoid (enteric) fever diagnosis.

Question 10

What is the term for a sudden outbreak of disease in a community in excess of normal expectation?

Accepted Answer

Answer reason: An epidemic is a sudden increase in disease occurrence above the expected level in a specific community or region; endemic is the usual baseline level, pandemic is worldwide spread, and isolation is a control measure.

Question 11

What is the vector of trench fever?

Accepted Answer

Answer reason: Trench fever is caused by Bartonella quintana and is transmitted by the human body louse (Pediculus humanus corporis).

Question 12

Which of the following is a retrovirus?

Accepted Answer

Answer reason: HIV is a lentivirus in the Retroviridae family. Rotavirus is a reovirus, herpes simplex virus is a DNA herpesvirus, and measles virus is a paramyxovirus.

Question 13

The Widal test is used for the diagnosis of which disease?

Accepted Answer

Answer reason: Widal is a serologic agglutination test detecting antibodies to Salmonella typhi O and H antigens, used to diagnose typhoid fever.

Question 14

Typhoid fever is caused by?

Accepted Answer

Answer reason: Typhoid fever is caused by the bacterium Salmonella enterica serovar Typhi, a gram-negative bacillus transmitted via the fecal–oral route. It invades the intestinal mucosa and disseminates systemically, producing sustained fever and abdominal symptoms. It is not a viral, fungal, or allergic condition.

Question 15

Tuberculosis caused by?

Accepted Answer

Answer reason: Tuberculosis is caused by the bacterium Mycobacterium tuberculosis, an acid-fast bacillus with a mycolic acid–rich cell wall. It is transmitted via airborne droplet nuclei and primarily affects the lungs but can be systemic. It is not caused by viruses, fungi, or helminths such as nematodes.

Question 16

Malaria is caused by?

Accepted Answer

Answer reason: Malaria is caused by protozoan parasites of the genus Plasmodium, including P. falciparum and P. vivax. These organisms are transmitted to humans through the bite of infected female Anopheles mosquitoes. Malaria is not caused by viruses, bacteria, or fungi, making those options incorrect.

Question 17

Incidence of TB in a community measured by?

Accepted Answer

Answer reason: Community incidence of tuberculosis disease is tracked by new smear-positive pulmonary TB cases, since smear positivity indicates active infectious disease and is used for program surveillance. Tuberculin/Mantoux positivity reflects infection or exposure and better estimates prevalence, not incidence of disease. Culture is diagnostic but not the standard population indicator for incidence because of resource and time constraints. Thus, sputum smear positive cases best measure TB incidence in the community.

Question 18

Athlete's foot is caused by?

Accepted Answer

Answer reason: Athlete’s foot (tinea pedis) is a superficial dermatophyte infection most commonly caused by Trichophyton species. These are fungi that invade keratinized tissues of the feet. Viruses and bacteria do not cause this pattern of interdigital scaling and pruritus, and protozoa are not etiologic agents of superficial skin infections.

Question 19

Which of the following is excluded as occupational disease due to biological agent?

Accepted Answer

Answer reason: Leptospirosis, brucellosis, and anthrax are classic zoonotic infections recognized as occupational diseases due to biological agents. They are associated with specific work exposures such as farming, abattoir work, veterinary practice, sewer work, and handling animal hides or wool. Standard occupational disease lists include all three conditions. Therefore, none of the listed diseases is excluded.

Question 20

Which of the Following is a viral disease?

Accepted Answer

Answer reason: Smallpox is caused by the variola virus, a classic example of a viral disease. In contrast, tetanus is caused by the bacterium Clostridium tetani. (Note: polio and mumps are also viral illnesses, but smallpox is the prototypical viral disease typically expected in such items.)

Question 21

Hookworm infection leads to deficiency of?

Accepted Answer

Answer reason: Hookworms (Ancylostoma duodenale and Necator americanus) attach to the intestinal mucosa and ingest blood while secreting anticoagulants, causing chronic blood loss. Persistent occult gastrointestinal bleeding leads to depletion of body iron stores. The hallmark consequence is iron-deficiency anemia, especially with high worm burden or poor dietary iron. Deficiencies of vitamin B12, vitamin A, or folate are not typical effects of hookworm infection.

Question 22

Antiseptic method were first introduced by;?

Accepted Answer

Answer reason: Joseph (Lord) Lister pioneered antiseptic surgery in the 1860s by using carbolic acid (phenol) to sterilize instruments and clean wounds, dramatically reducing postoperative infections. Ivanovsky and Beijerinck are associated with the discovery and conceptualization of viruses, not surgical antisepsis. Edward Jenner is known for developing the smallpox vaccine. Therefore, Lister is the first to introduce antiseptic methods.

Question 23

Tuberculosis is a ...?

Accepted Answer

Answer reason: Tuberculosis is caused by Mycobacterium tuberculosis and spreads via airborne droplet nuclei (

Question 24

Food poisioning is caused by?

Accepted Answer

Answer reason: Foodborne botulism results from ingestion of preformed neurotoxin produced by Clostridium botulinum in improperly canned or preserved foods, making it a classic cause of food poisoning. Clostridium tetani causes tetanus via wound contamination, and diphtheria is caused by Corynebacterium diphtheriae, not a foodborne organism. Although C. perfringens (formerly C. welchii) can cause food poisoning, the best single answer here is botulism due to C. botulinum.

Question 25

Diagnostic test for syphilis?

Accepted Answer

Answer reason: VDRL and Kahn's test are non-treponemal serologic screening tests that detect reagin antibodies in syphilis. TPHA is a treponemal test used to confirm infection by detecting antibodies specific to Treponema pallidum. Since all listed tests are used in the diagnostic workup of syphilis, the best choice is All.

Question 26

Sleeping sickness is caused by...?

Accepted Answer

Answer reason: African sleeping sickness is caused by the protozoan Trypanosoma brucei (subspecies gambiense or rhodesiense), transmitted by the tsetse fly. The parasite invades the blood and central nervous system, leading to fever, lymphadenopathy, and progressive sleep disturbances and neurologic decline. Plasmodium causes malaria, not sleeping sickness. Leeches and lice are not the etiologic agents; lice more commonly transmit diseases like epidemic typhus.

Question 27

Malaria incubation period is usually?

Accepted Answer

Answer reason: For most malaria infections, especially Plasmodium falciparum, symptoms typically appear about 7–14 days after an infective mosquito bite. Other species can have longer or variable incubation (e.g., P. vivax/ovale may be 12–18 days and may relapse later, P. malariae up to weeks), but the usual window is around one to two weeks. Therefore, 7–14 days is the best single answer.

Question 28

Smallpox is caused by?

Accepted Answer

Answer reason: Smallpox is caused by the variola virus, a member of the Orthopoxvirus genus. Varicella virus (varicella-zoster) causes chickenpox and shingles, not smallpox. Rubella virus causes German measles, and Coxsackie viruses cause illnesses such as hand-foot-and-mouth disease and herpangina. Therefore, the correct etiologic agent of smallpox is variola virus.

Question 29

Break bone fever is-?

Accepted Answer

Answer reason: “Breakbone fever” is the classic nickname for dengue infection due to the severe myalgia and arthralgia that make patients feel as if their bones are breaking. Dengue is a mosquito-borne viral illness transmitted by Aedes mosquitoes. Typhoid fever and malaria are caused by different pathogens and are not referred to by this term, and “malignant fever” is nonspecific. Therefore, the best answer is dengue fever.

Question 30

Which of the following communicable disease is eradicated in our country?

Accepted Answer

Answer reason: Smallpox is the only human infectious disease that has been eradicated worldwide, certified by WHO in 1980. Poliomyelitis has been eliminated in some countries but not globally eradicated; sporadic cases still occur. Tuberculosis and filariasis remain endemic in many regions. Therefore, the eradicated disease is smallpox.

Question 31

Whooping cough is caused by?

Accepted Answer

Answer reason: Whooping cough (pertussis) is caused by Bordetella pertussis, a gram-negative coccobacillus that infects the respiratory epithelium. Its toxins lead to paroxysmal coughing fits with the characteristic inspiratory 'whoop,' especially in infants. It is not caused by viruses, fungi, or protozoa; vaccination with DTaP targets this bacterial pathogen.

Question 32

Dengue is also called?

Accepted Answer

Answer reason: Dengue fever is commonly termed breakbone fever due to the intense myalgia and arthralgia that make patients feel as if their bones are breaking. It is caused by dengue virus transmitted by Aedes mosquitoes. Blackwater fever is a complication of Plasmodium falciparum malaria, spotted fever refers to rickettsial infections, and yellow fever is a distinct flavivirus disease.

Question 33

Mumps can cause which complication in males?

Accepted Answer

Answer reason: Mumps, a paramyxovirus infection, commonly causes parotitis but in postpubertal males it can lead to epididymo-orchitis, presenting with testicular pain and swelling. This complication may transiently impair spermatogenesis and rarely causes infertility. Appendicitis and hepatitis are not typical complications of mumps, and otitis is more associated with bacterial or other viral upper respiratory infections rather than mumps.

Question 34

What is the primary cause of maleria?

Accepted Answer

Answer reason: Malaria is caused by Plasmodium species, which are protozoan parasites transmitted by female Anopheles mosquitoes. The mosquito acts as the vector, not the etiologic agent. It is therefore not a viral, bacterial, or fungal disease.

Question 35

Sub-acute Sclerosing Pan Encephalitis (SSPE) can occur in infection with?

Accepted Answer

Answer reason: SSPE is a rare, progressive, and often fatal demyelinating disease of the CNS caused by persistent infection with a mutant measles virus. It typically appears years after a primary measles infection, especially when the initial illness occurred at a young age. Rubella, mumps, and varicella are not etiologically linked to SSPE.

Question 36

Which of the following communicable disease is not transmitted by Aedes mosquito?

Accepted Answer

Answer reason: Aedes aegypti and Aedes albopictus transmit arboviruses such as dengue, yellow fever, and chikungunya. Japanese encephalitis is primarily transmitted by Culex mosquitoes, especially Culex tritaeniorhynchus, in rural and peri-urban areas. Therefore, among the options listed, Japanese encephalitis is not transmitted by Aedes mosquitoes.

Question 37

The bacterium Yersinia pestis causes ____?

Accepted Answer

Answer reason: Yersinia pestis is a gram-negative coccobacillus transmitted primarily by flea vectors and is the etiologic agent of plague, classically presenting as bubonic plague with painful swollen lymph nodes (buboes). It can also cause septicemic and pneumonic forms. Rubella and measles are viral illnesses, not bacterial, and roseola is caused by human herpesvirus 6/7. Therefore, the only correct match is bubonic plague.

Question 38

Which of the following is potent compound for chlorination of water?

Accepted Answer

Answer reason: Hypochlorous acid (HOCl) is the most potent antimicrobial species formed during chlorination. It is a stronger oxidant than the hypochlorite ion (OCl−) and more readily penetrates microbial cell walls, leading to rapid inactivation. The HOCl:OCl− balance depends on pH, with lower pH favoring the more effective HOCl form. 'Free residual chlorine' includes both species, but HOCl is the specific potent compound.

Question 39

Which disease is not spread through water?

Accepted Answer

Answer reason: Cholera, hepatitis A, and typhoid are transmitted via the fecal–oral route and commonly spread through contaminated water or food. Asthma is a chronic inflammatory airway disease that is not infectious and is not spread through water. Therefore, asthma is the condition not transmitted by water.

Question 40

Which is the correct statement related to hepatitis B virus?

Accepted Answer

Answer reason: Hepatitis B virus belongs to the Hepadnaviridae family (hepadnavirus), an enveloped, partially double‑stranded DNA virus. Although it uses reverse transcription in replication, it is not a retrovirus. Paramyxoviruses and orthomyxoviruses are RNA viruses associated with diseases like measles/mumps and influenza, respectively, and are unrelated to HBV classification.

Question 41

Study of Fungi is called?

Accepted Answer

Answer reason: Mycology is the branch of microbiology that focuses on fungi, including yeasts, molds, and mushrooms—their biology, classification, and diseases they cause. Cytology studies cells, oncology deals with cancers, neology concerns new words, and aerology pertains to the atmosphere. Therefore, Mycology is the correct term.

Question 42

Dengue prevention mainly involves?

Accepted Answer

Answer reason: Dengue is a viral disease transmitted by Aedes mosquitoes, so prevention focuses on reducing vector populations and avoiding bites (eliminating standing water, insecticides, nets, repellents). Antibiotics and antifungals are ineffective because the pathogen is a virus. Although dengue vaccines exist, their use is limited to specific populations and settings; they are not the primary prevention strategy. Therefore, mosquito control is the main preventive measure.

Question 43

Severe malaria is most commonly caused by?

Accepted Answer

Answer reason: Plasmodium falciparum is responsible for the majority of severe and life-threatening malaria. It infects erythrocytes of all ages, leading to high parasitemia and cytoadherence with microvascular sequestration, which causes complications such as cerebral malaria, severe anemia, and organ failure. P. vivax, P. ovale, and P. malariae typically cause milder disease, with vivax and ovale notable for relapses rather than severity.

Question 44

Typhoid fever is caused by?

Accepted Answer

Answer reason: Typhoid fever is caused by Salmonella enterica serovar Typhi, a Gram-negative bacillus transmitted via the fecal–oral route. It invades intestinal mucosa and Peyer’s patches, leading to systemic bacteremia and prolonged fever. Escherichia coli typically causes diarrheal illness and urinary tract infections; Vibrio cholerae causes cholera; and Shigella dysenteriae causes bacillary dysentery, not typhoid.

Question 45

Ringworm is caused by?

Accepted Answer

Answer reason: Ringworm (tinea) is a superficial dermatophyte infection caused by fungi such as Trichophyton, Microsporum, and Epidermophyton species. The term is a misnomer; no worms are involved. Viral, bacterial, and protozoal pathogens do not produce the characteristic annular scaly lesions of tinea.

Question 46

Which mosquito transmits dengue virus?

Accepted Answer

Answer reason: Dengue virus is transmitted primarily by Aedes mosquitoes, especially Aedes aegypti and Aedes albopictus, which are day-biting and thrive in urban environments. Culex species more commonly transmit illnesses like West Nile and Japanese encephalitis. Anopheles is the principal vector for malaria, not dengue. Tabanus (horsefly) is not a mosquito and is not a vector for dengue.

Question 47

Which of the following is a viral disease?

Accepted Answer

Answer reason: Measles is caused by the measles virus (a Morbillivirus in the Paramyxoviridae family). In contrast, typhoid is due to Salmonella enterica serovar Typhi, cholera is caused by Vibrio cholerae, and leprosy is caused by Mycobacterium leprae—each a bacterium. Therefore, among the options, only measles is a viral disease.

Question 48

According to the Lancefield scheme of classifying the Streptococcus species, the enterococci are placed in __________ group?

Accepted Answer

Answer reason: Lancefield classification groups streptococci based on cell wall C-carbohydrate antigens. Enterococci (e.g., Enterococcus faecalis and E. faecium) carry the group D antigen and were historically classified as group D streptococci. Thus, in the Lancefield scheme they are placed in group D.

Question 49

Yeast is an example of?

Accepted Answer

Answer reason: Yeasts are unicellular eukaryotic organisms classified within the fungi kingdom. They reproduce by budding or fission and possess chitin in their cell walls, distinguishing them from bacteria and viruses. Algae are photosynthetic protists, not responsible for typical yeast characteristics.

Question 50

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

Accepted Answer

Answer reason: Normal gut microbiota in the colon synthesize menaquinones (vitamin K2) as part of a mutualistic relationship with the host. These symbiotic bacteria benefit from nutrients in the intestine while providing vitamin K that supports hepatic synthesis of clotting factors. Loss of this flora (e.g., after broad-spectrum antibiotics) can reduce vitamin K production and increase bleeding risk. Thus, the activity is best described as symbiotic.

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

Microbiology NCLEX Practice Test

Continue Learning

Vaccination against mumps can prevent which condition?

Which of the following bacteria can cause peptic ulcer?

Which test is used to detect HIV?

Which are the biological agents?

Which disease is also known as Hansen's disease?

Sleeping sickness in man is caused by which organism?

What is the causative organism of chickenpox?

A client is diagnosed with AIDS. The nurse recognizes that an opportunistic infection is present when the oral cavity is examined and white plagues are discovered on the mucosa. What does this finding most likely represent?

The Widal test is used for the diagnosis of which disease?

What is the term for a sudden outbreak of disease in a community in excess of normal expectation?

What is the vector of trench fever?

Which of the following is a retrovirus?

The Widal test is used for the diagnosis of which disease?

Typhoid fever is caused by?

Tuberculosis caused by?

Malaria is caused by?

Incidence of TB in a community measured by?

Athlete's foot is caused by?

Which of the following is excluded as occupational disease due to biological agent?

Which of the Following is a viral disease?

Hookworm infection leads to deficiency of?

Antiseptic method were first introduced by;?

Tuberculosis is a ...?

Food poisioning is caused by?

Diagnostic test for syphilis?

Sleeping sickness is caused by...?

Malaria incubation period is usually?

Smallpox is caused by?

Break bone fever is-?

Which of the following communicable disease is eradicated in our country?

Whooping cough is caused by?

Dengue is also called?

Mumps can cause which complication in males?

What is the primary cause of maleria?

Sub-acute Sclerosing Pan Encephalitis (SSPE) can occur in infection with?

Which of the following communicable disease is not transmitted by Aedes mosquito?

The bacterium Yersinia pestis causes ____?

Which of the following is potent compound for chlorination of water?

Which disease is not spread through water?

Which is the correct statement related to hepatitis B virus?

Study of Fungi is called?

Dengue prevention mainly involves?

Severe malaria is most commonly caused by?

Typhoid fever is caused by?

Ringworm is caused by?

Which mosquito transmits dengue virus?

Which of the following is a viral disease?

According to the Lancefield scheme of classifying the Streptococcus species, the enterococci are placed in __________ group?

Yeast is an example of?

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

Think you’re ready for the NCLEX?

Leave a Reply Cancel reply