Medical Microbiology Quiz Questions And Answers

Hepatitis B is caused by the DNA virus hepadnavirus, which is primarily transmitted through blood and bodily fluids. This includes activities such as unprotected sexual contact, sharing needles or other drug paraphernalia, and from an infected mother to her baby during childbirth. It is not transmitted through airborne, waterborne, or foodborne routes.

Dogs, foxes, and bats are vectors that can carry rabies. Rabies is a viral disease that affects the nervous system and can be transmitted to humans through the saliva of infected animals. Dogs are one of the most common carriers of rabies, especially in regions where vaccination programs are not well-established. Foxes can also carry and transmit the virus, particularly in rural areas. Bats are natural reservoirs for the rabies virus and can transmit it through bites or scratches. It is important to be cautious around these animals to prevent the spread of rabies.

Mosquitos can carry and transmit the dengue virus, which causes dengue fever. Dengue hemorrhagic fever is a severe form of dengue fever that can lead to bleeding, organ damage, and even death. It is transmitted to humans through the bite of infected mosquitos, primarily the Aedes aegypti mosquito. Symptoms of dengue hemorrhagic fever include high fever, severe headache, joint and muscle pain, rash, and bleeding. It is important to prevent mosquito bites and control mosquito breeding sites to reduce the risk of dengue hemorrhagic fever.

Retroviruses are known to cause AIDS. HIV, which is a type of retrovirus, attacks the immune system and weakens it, leading to the development of AIDS. Retroviruses have the ability to integrate their genetic material into the DNA of the host cells, allowing them to replicate and persist in the body. This integration process and the destruction of immune cells by HIV ultimately result in the progression of AIDS, a severe and life-threatening condition.

Salmonella is a type of bacteria that can cause enteric fever and gastroenteritis in the elderly. Enteric fever is a systemic infection characterized by high fever, abdominal pain, and diarrhea. Gastroenteritis, on the other hand, is an inflammation of the stomach and intestines that leads to symptoms such as nausea, vomiting, diarrhea, and abdominal pain. Both conditions can be caused by the ingestion of food or water contaminated with Salmonella bacteria.

Clostridia spp, including Cl. tetani, Cl. perfringens, and Cl. botulinum, are anaerobic gram-positive bacilli. They are known to cause tetanus, gas gangrene, and botulism. Tetanus is a condition characterized by muscle stiffness and spasms, usually caused by the toxin produced by Cl. tetani. Gas gangrene is a severe infection that leads to tissue death and is caused by Cl. perfringens. Botulism is a rare but serious illness caused by the toxin produced by Cl. botulinum, leading to muscle weakness and paralysis.

Papillomavirus is known to cause cervical cancer. This virus is transmitted through sexual contact and can infect the cells of the cervix, leading to abnormal cell growth and potentially developing into cancer over time. It is important to note that not all strains of papillomavirus cause cancer, but certain high-risk strains, such as HPV 16 and HPV 18, are strongly associated with cervical cancer development. Regular screening and vaccination against these high-risk strains can help prevent cervical cancer.

Haemophilus influenza is a bacterium that causes respiratory and central nervous system (CNS) infections, particularly in infants. It is known to cause conditions such as pneumonia, meningitis, and otitis media. This bacterium can be transmitted through respiratory droplets and can lead to severe illness in young children, making it important to vaccinate against it.

Streptococcus pneumoniae is a bacterium that causes various infections, including pneumonia, otitis media (middle ear infection), and meningitis. These infections can affect different parts of the body and can lead to serious complications if not treated properly. Streptococcus pneumoniae is a common cause of pneumonia, especially in children and the elderly. It can also cause otitis media, an infection of the middle ear, and meningitis, an infection of the membranes surrounding the brain and spinal cord.

Candida albicans is a commensal yeast that commonly resides on the skin and mucous membranes of humans. It can cause thrush, which is an infection characterized by white patches on the tongue and inside the mouth. It can also cause mucocutaneous infections, which affect the skin and mucous membranes. This yeast is opportunistic and can cause infections when the immune system is weakened or when there is an imbalance in the normal microbial flora.

Escherichia coli (E. coli) is a gram-negative bacteria that commonly causes urinary tract infections (UTIs). UTIs occur when E. coli bacteria enter the urethra and travel up to the bladder or kidneys. E. coli is found in the intestines and is a normal part of the gut flora, but when it enters the urinary tract, it can cause infection and inflammation. It is the most common cause of UTIs, accounting for about 80-90% of cases. Neisseria gonorrhoeae and Neisseria meningitidis are gram-negative bacteria that can cause other types of infections, while Salmonella is primarily associated with foodborne illnesses.

The clinical manifestation of poliovirus is spinal paralysis. Poliovirus primarily affects the nervous system, specifically the motor neurons in the spinal cord. This can result in muscle weakness, loss of reflexes, and ultimately paralysis. Other symptoms may include fever, headache, and sore throat, but the most significant manifestation is the paralysis.

Staphylococcus aureus is commonly found on the skin. It is a bacteria that can cause various infections, including skin infections such as boils, impetigo, and cellulitis. It is part of the normal flora of the skin and can be found in the nose and throat as well. Staphylococcus aureus can also cause more serious infections if it enters the bloodstream or other parts of the body.

The word "symbiotic" describes a mutually beneficial relationship between two organisms. In a symbiotic relationship, both organisms benefit from each other's presence. This can be seen in various examples such as the relationship between bees and flowers, where bees obtain nectar for food while also pollinating the flowers. Similarly, some bacteria in our gut help with digestion and in return, they receive a suitable environment to thrive. Therefore, "symbiotic" is the correct answer as it accurately represents a mutually beneficial relationship.

Plasmodia is a type of protozoa that causes malaria. Malaria is a mosquito-borne infectious disease that affects humans and other animals. The plasmodia parasite is transmitted to humans through the bite of infected female Anopheles mosquitoes. Once inside the human body, the parasites multiply in the liver and then infect red blood cells, causing symptoms such as fever, chills, and flu-like illness. If left untreated, malaria can be life-threatening. Therefore, the correct answer is Malaria.

Mycobacterium tuberculosis is classified as Acid-fast Bacilli because it is a type of bacteria that retains a stain even after being washed with acid-alcohol. This staining characteristic is due to the presence of a waxy substance called mycolic acid in their cell walls. Acid-fast Bacilli are commonly associated with diseases such as tuberculosis, which is caused by Mycobacterium tuberculosis.

Salmonella is classified as a Gram-negative bacilli. Gram-negative bacteria have a thin peptidoglycan layer in their cell wall, which does not retain the crystal violet stain during the Gram staining process. Salmonella is known to cause enteric fever (typhoid) and food poisoning, and its classification as a Gram-negative bacilli is consistent with its characteristics and behavior.

Dengue viruses 1-4 are transmitted through a vector. This means that they are spread by the bite of infected mosquitoes, specifically the Aedes species. These mosquitoes become infected when they bite a person who already has the virus in their bloodstream. The virus then replicates within the mosquito and can be transmitted to other individuals when the infected mosquito bites them. This is the primary mode of transmission for dengue viruses 1-4.

Beta-lactam antibiotics work by affecting cell wall synthesis. These antibiotics inhibit the formation of peptidoglycan, a major component of bacterial cell walls, leading to weakened cell walls and ultimately bacterial cell death. This mechanism of action is specific to beta-lactam antibiotics, making them effective against a wide range of bacterial infections. Examples of beta-lactam antibiotics include penicillins, cephalosporins, and carbapenems.

Poliovirus is not an airborne virus because it is primarily transmitted through the fecal-oral route, meaning it spreads through contaminated food or water. It does not spread through respiratory droplets like airborne viruses such as respiratory syncytial virus, parainfluenza virus, and measles virus, which can be transmitted through coughing, sneezing, or close contact with an infected person.

Shigella spp is the correct answer because it is a gram-negative bacilli that is known to cause dysentery. Shigella bacteria are responsible for Shigellosis, a highly contagious infection that affects the intestines and causes symptoms such as diarrhea, abdominal pain, and fever. Other options such as Proteus spp, Klebsiella spp, and Pseudomonas aeruginosa are not typically associated with causing dysentery.

Streptococcus pneumoniae is not a gram-negative bacteria because it is a gram-positive bacteria. Gram-negative bacteria have a thin peptidoglycan layer in their cell wall, while gram-positive bacteria have a thick peptidoglycan layer. Streptococcus pneumoniae is classified as gram-positive because it stains purple in the Gram staining process, indicating the presence of a thick peptidoglycan layer in its cell wall.

Togaviruses, including rubella and alphaviruses, are known to cause German measles (also known as rubella) and encephalitis. German measles is a viral infection that causes a rash and flu-like symptoms, while encephalitis is inflammation of the brain. This explanation aligns with the given correct answer.

Staphylococcus aureus is a bacterium that can cause a range of infections in humans. It is known to cause boils, which are painful, pus-filled bumps on the skin. It can also cause septicaemia, which is a severe bloodstream infection. Staphylococcus aureus is a common cause of food poisoning, often from contaminated food. Additionally, it can cause wound infections, leading to delayed healing and potential complications. Therefore, the correct answer is that Staphylococcus aureus causes boils, septicaemia, food poisoning, and wound infections.

Enteroviruses are contracted through the consumption of contaminated food. This can occur when food is prepared or handled by individuals who are infected with the virus and fail to practice proper hygiene. Ingesting contaminated food allows the virus to enter the digestive system and cause infection. Therefore, the correct answer is "Foodborne."

Macrolides are a class of antibiotics that work by binding to the 50S subunit of the ribosome, which is responsible for protein synthesis. This binding inhibits the translocation of the growing peptide chain, effectively stopping the synthesis of proteins in bacteria. Streptomycin and gentamycin are not macrolides, so they are not examples of this class of antibiotics. On the other hand, erythromycin, azithromycin, and clarithromycin are all macrolides, making them the correct answer to the question. Vancomycin and amoxicillin are not macrolides and are therefore not examples of this class of antibiotics.

Rhinitis is a condition characterized by inflammation of the nasal passages, leading to symptoms such as a runny or stuffy nose, sneezing, and nasal congestion. It is commonly caused by viruses that are transmitted through respiratory droplets. The viruses listed in the answer choices - Coronavirus, Parainfluenza virus, and Respiratory syncytial virus - are all known to cause respiratory infections and can lead to the development of rhinitis. Influenza virus and Adenovirus can also cause respiratory symptoms, but they are not specifically mentioned in relation to rhinitis. Epstein-Barr virus and Measles virus are not typically associated with rhinitis.

Hepatitis A is not a bloodborne virus. It is primarily transmitted through the fecal-oral route, usually by consuming contaminated food or water. In contrast, HIV, Hepatitis B, and Hepatitis D are all bloodborne viruses, meaning they are transmitted through contact with infected blood or other body fluids.

Warts are caused by the viruses MCV (Molluscum contagiosum virus) and papillomavirus. MCV is a poxvirus that causes small, raised, flesh-colored bumps on the skin. Papillomavirus, on the other hand, is a DNA virus that infects the skin and mucous membranes, causing various types of warts, such as common warts, plantar warts, and genital warts. These viruses are transmitted through direct contact with an infected person or by touching surfaces that have the virus on them.

Beta-haemolytic streptococci cause tonsillitis, cellulitis, scarlet fever, and septicaemia. These bacteria are known to be pathogenic and can cause a range of infections in humans. Tonsillitis is an infection of the tonsils, cellulitis is a skin infection, scarlet fever is a bacterial infection that causes a red rash and high fever, and septicaemia is a severe bloodstream infection. Staphylococcus aureus, Clostridia spp, and Pseudomonas aeruginosa are also pathogenic bacteria, but they are not specifically associated with causing these particular infections.

Dermatophytes are the fungi that cause ringworm. They are a group of fungi that infect the skin, hair, and nails, causing various types of ringworm infections. These fungi thrive in warm and moist environments and can be transmitted through direct contact with infected humans or animals, or by sharing contaminated objects. Dermatophytes feed on keratin, a protein found in the outer layers of the skin, hair, and nails, leading to the characteristic symptoms of ringworm, such as red, itchy, and scaly patches on the skin.

Spring fatigue, Burkitt lymphoma, and nasopharynx carcinoma are all conditions that can be caused by the Epstein-Barr virus (EBV). EBV is a common virus that is transmitted through saliva and can cause various illnesses, including infectious mononucleosis (also known as "mono") and certain types of cancer, such as Burkitt lymphoma and nasopharynx carcinoma. Therefore, EBV is the virus that can cause these conditions.

Neisseria gonorrhoeae is a bacterium that causes the sexually transmitted infection gonorrhoea. It is classified as Gram-negative cocci based on its shape and the color it retains after a Gram staining procedure. Gram-negative bacteria have a thin peptidoglycan layer in their cell wall, which does not retain the crystal violet stain used in the Gram staining process. Instead, they appear pink or red when counterstained with safranin. This classification is important for identifying and treating the infection, as it helps determine the appropriate antibiotics to use.

Gram-positive cell walls are composed of a thick layer of peptidoglycan, which makes up the majority of the cell wall. This layer is responsible for providing structural integrity to the cell and protecting it from osmotic stress. The correct answer, 90-95%, indicates that peptidoglycan makes up a significant proportion of the Gram-positive cell wall, highlighting its importance in the overall structure and function of these bacterial cells.

Quinolones and fluoroquinolones are groups of antibiotics that work by affecting nucleic acid function or synthesis. These antibiotics inhibit the activity of bacterial DNA gyrase and topoisomerase IV enzymes, which are essential for DNA replication, transcription, and repair. By targeting these enzymes, quinolones and fluoroquinolones disrupt the bacterial DNA synthesis process, leading to inhibition of bacterial growth and ultimately killing the bacteria. This mechanism of action makes them effective against a wide range of bacterial infections.

Gastroenteritis is caused by the ingestion of Caliciviruses, Adenovirus 40 and 41, and Rotavirus. These viruses can be transmitted through contaminated food or water, leading to inflammation of the stomach and intestines. Hepatitis A is a separate viral infection that affects the liver, while Poliovirus, HSV, CMV, and JC-virus do not typically cause gastroenteritis.

The correct answer is Monkey. Ebola and Marburg viruses are primarily carried by non-human primates, particularly monkeys. These viruses can be transmitted to humans through contact with infected monkeys or their bodily fluids. Monkeys serve as a reservoir for these viruses, allowing them to persist and potentially spread to other animals or humans. It is important to understand the role of vectors in the transmission of diseases in order to implement effective control and prevention measures.

Poliovirus is contracted through direct contact or ingestion. This means that the virus can be spread by coming into contact with the feces or respiratory secretions of an infected person, or by consuming contaminated food or water. This mode of transmission highlights the importance of practicing good hygiene, such as washing hands thoroughly and ensuring proper sanitation, to prevent the spread of the virus.

Corynebacterium diphtheriae is a bacterium that causes diphtheria, which is a respiratory infection. It is classified as a Gram-positive bacilli. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which retains the crystal violet stain during the Gram staining process, causing them to appear purple under a microscope. Bacilli refers to the shape of the bacteria, which are rod-shaped. This classification helps in identifying and treating the infection caused by this specific bacterium.

Aminoglycosides such as streptomycin and gentamycin interact with the 30S subunit of ribosomes. These antibiotics inhibit protein synthesis by binding to the ribosomes and causing misreading of the genetic code, ultimately leading to bacterial cell death. Erythromycin, azithromycin, and clarithromycin are examples of macrolide antibiotics, not aminoglycosides. Vancomycin is a glycopeptide antibiotic, and penicillin is a beta-lactam antibiotic. Therefore, the correct examples of aminoglycosides are streptomycin and gentamycin.

Flaviviruses cause yellow fever and chronic hepatitis. Yellow fever is a viral infection transmitted by mosquitoes, and it can cause symptoms such as fever, headache, jaundice, and organ failure. Chronic hepatitis, on the other hand, is a long-term inflammation of the liver caused by viral infection. Flaviviruses are a family of RNA viruses that include several well-known viruses such as dengue fever, Zika virus, West Nile virus, and Japanese encephalitis virus. Therefore, the correct answer is Flaviviruses.

Measles virus is contracted through the respiratory route, meaning it can be transmitted through respiratory droplets when an infected person coughs or sneezes. These droplets can then be inhaled by others, leading to infection. This is a common mode of transmission for many respiratory viruses, including measles.

Hantaviruses are primarily carried by mice and rats. These rodents act as the reservoir hosts for the virus, meaning that they can carry and transmit it to humans. When infected rodents shed the virus in their urine, droppings, or saliva, humans can become infected through direct contact or inhalation of contaminated materials. Therefore, mice and rats are the vectors that carry hantaviruses and can cause various illnesses such as haemorrhagic fever with renal syndrome, pneumonia, nephritis, and encephalitis.

Variola is not a herpesvirus. Variola virus is the causative agent of smallpox, which is a highly contagious and deadly disease. It belongs to the family Poxviridae, not Herpesviridae. The other options, Varicella zoster virus (causes chickenpox and shingles), Epstein-Barr virus (causes infectious mononucleosis), and Cytomegalovirus (causes a variety of infections), are all herpesviruses.

RNA orthomyxoviruses cause influenza, which is a viral infection that affects the respiratory system. Influenza is characterized by symptoms such as fever, cough, sore throat, body aches, and fatigue. It is a highly contagious illness that can spread rapidly, especially during flu seasons. The RNA orthomyxoviruses, including influenza A, B, and C viruses, are responsible for causing seasonal flu outbreaks and occasional pandemics. These viruses undergo frequent genetic changes, making it necessary to develop new vaccines each year to provide protection against the most prevalent strains.

Metronidazole is the first choice for anaerobic infections because it is specifically effective against anaerobic bacteria. Anaerobic infections occur in environments without oxygen, such as deep wounds or the gastrointestinal tract. Metronidazole works by disrupting the DNA of anaerobic bacteria, leading to their death. Amoxycillin, Gentamicin, and Vancomycin are not as effective against anaerobic bacteria and are more commonly used for other types of infections. Therefore, Metronidazole is the preferred drug for treating anaerobic infections.

Trimetroprim works by inhibiting the folic acid converting enzyme. Folic acid is essential for the synthesis of DNA, RNA, and proteins in bacteria. By inhibiting the enzyme responsible for converting folic acid, Trimetroprim disrupts these processes, leading to the inhibition of bacterial growth and the eventual death of the bacteria. Amoxicillin, Metronidazole, and Rifampicin have different mechanisms of action and do not directly inhibit the folic acid converting enzyme.

Subacute Sclerosing Panencephalitis (SSPE) is a rare and progressive neurological disorder that occurs as a late complication of measles infection. It is caused by a persistent infection of the measles virus in the brain. SSPE typically develops several years after the initial measles infection, and it is characterized by a gradual deterioration of mental and motor functions. The measles virus is known to persist in the body, particularly in the brain, and can lead to SSPE in some individuals. Other viruses, such as EBV (Epstein-Barr virus) and HIV, do not cause SSPE. Glandular fever is another term for infectious mononucleosis, which is caused by the Epstein-Barr virus and is not associated with SSPE.

Adenoviruses and herpesviruses are both capable of causing hepatitis when they are ingested or come into direct contact with the body. Hepatitis is an inflammation of the liver, and these viruses can infect liver cells and cause damage to the organ. Adenoviruses are a group of viruses that can cause a wide range of illnesses, including respiratory and gastrointestinal infections. Herpesviruses, on the other hand, are a family of viruses that can cause various diseases, including oral and genital herpes. Both types of viruses have been associated with cases of hepatitis.

Herpes viruses are known to cause various diseases, including chickenpox, shingles, glandular fever, and roseola infantum. However, warts are not caused by herpes viruses. Warts are typically caused by the human papillomavirus (HPV), which is a different type of virus. While both herpes viruses and HPV are common and can cause different types of infections, warts specifically are not associated with herpes viruses.