Microbiology MCQs with Answer and Explnation | Chapter 15

Answer: Tetracyclines and Erythromycin

• Tetracyclines: Tetracycline antibiotics, such as doxycycline, are often used for the treatment of Mycoplasma infections.
• Erythromycin: Erythromycin, a macrolide antibiotic, is another option for treating Mycoplasma infections.

The other options are incorrect:

• Penicillins: Penicillins are generally not effective against Mycoplasma because Mycoplasma lack a cell wall, which is the target of penicillins.

Answer: Mycoplasma phages

Bacteriophages are viruses that infect bacteria, and Mycoplasma phages specifically target mycoplasmas, which are a type of bacteria that lack a cell wall.
These phages are viruses that specifically infect mycoplasmas.

The other options are incorrect:

• Bacteriophages: While bacteriophages infect bacteria, the question is specifically asking about viruses that infect mycoplasmas.
• Virions: Virions are complete virus particles, and the term doesn’t specifically refer to

Answer: R.orinetalis

Scrub typhus is caused by Orientia tsutsugamushi, formerly known as Rickettsia tsutsugamushi. It is transmitted to humans by the bite of infected chiggers (larval mites). The bacterium is an obligate intracellular pathogen and is the causative agent of scrub typhus.

The other options are incorrect:

• R. Quintana: Rickettsia quintana is associated with trench fever, transmitted by body lice, and is not the causative agent of scrub typhus.
• R. rickettsii: Rickettsia rickettsii causes Rocky Mountain spotted fever, not scrub typhus.
• R. prowazekii: Rickettsia prowazekii is the agent of epidemic typhus, which is transmitted by body lice, and is not associated with scrub typhus.

Answer: C.trachomatis

Lymphogranuloma venereum (LGV) is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. It primarily affects the lymphatic system and can lead to genital ulcers and swollen lymph nodes.

The other options are incorrect:

• C. pneumoniae: Chlamydia pneumoniae is associated with respiratory tract infections but is not the causative agent of LGV.
• C. psittaci: Chlamydia psittaci causes psittacosis, a disease transmitted from birds to humans, and is not associated with LGV.
• C. opthalmia: This is not a recognized species within the Chlamydia genus, and it is not associated with LGV.

Answer: Frei test

The Frei test is an intradermal skin test that is used to diagnose lymphogranuloma venereum (LGV), a sexually transmitted infection (STI) caused by specific strains of the bacterium Chlamydia trachomatis. The test involves injecting a small amount of antigen prepared from the pus of an infected lymph node into the skin of the forearm. If the person is infected with LGV, a raised bump will form at the injection site within 48 to 72 hours.

The other options are incorrect:

• Mantoux test is an intradermal skin test that is used to diagnose tuberculosis.
• Schick test is an intradermal skin test that was once used to assess immunity to diphtheria. It is no longer used routinely.
• Dick test is an intradermal skin test that was once used to assess immunity to scarlet fever. It is no longer used routinely.

Answer: Prototheca

Prototheca is a genus of green algae that lack chlorophyll and are obligate intracellular parasites of mammals, including humans. They can cause a rare but potentially fatal infection called protothecosis. Prototheca species are ubiquitous in nature and can be found in soil, water, and the feces of animals. They are typically transmitted to humans through contact with contaminated soil or water, or through inhalation of aerosolized prototheca cells.

The other options are incorrect:

• Cephaloeuros is a genus of green algae that are typically found in freshwater environments. They are not known to be pathogenic to humans.
• Ulothrix is a genus of green algae that are typically found in freshwater and marine environments. They are not known to be pathogenic to humans.
• Macrocystis is a genus of brown algae that are typically found in marine environments. They are not known to be pathogenic to humans.

Answer: S.erythraeus

Erythromycin is a macrolide antibiotic that is produced by the bacterium Saccharopolyspora erythraea (formerly Streptomyces erythraeus). It inhibits bacterial protein synthesis by binding to the 50S subunit of the ribosome.

The other options are incorrect:

• S.griseus: Streptomyces griseus is known for producing streptomycin, not erythromycin.
• S.rimosus: Streptomyces rimosus is known for producing oxytetracycline, not erythromycin.
• S.scabies: Streptomyces scabies is known for producing thaxtomin, which is associated with potato scab disease, not erythrom

Answer: Adeno virus

Adenoviruses are a common cause of viral conjunctivitis. Adenoviral conjunctivitis is highly contagious and can cause redness, tearing, and discomfort in the eyes.

The other options are incorrect:

• Coronavirus: Coronaviruses are more commonly associated with respiratory infections and not a typical cause of conjunctivitis.
• Paramyxovirus: Paramyxoviruses are a family of viruses that includes various respiratory viruses, but they are not commonly implicated in conjunctivitis. Adenoviruses are more closely associated with this condition.

Answer: Tetracyclines

Tetracyclines, such as doxycycline, are commonly used antibiotics for the treatment of cholera. They are effective against Vibrio cholerae, the bacterium that causes cholera.

The other options are incorrect:

• Penicillins: Penicillins are generally not the first-line treatment for cholera. Tetracyclines and fluoroquinolones are more commonly used.
• Streptomycins: Streptomycin is not typically used as a first-line treatment for cholera. Tetracyclines and other antibiotics are more commonly prescribed.

Answer: Enteric fever

Salmonella typhi is the causative organism of enteric fever, also known as typhoid fever. This bacterial infection is characterized by symptoms such as prolonged fever, abdominal pain, headache, and gastrointestinal issues.

The other options are incorrect:

• Undulent fever: Brucella species are associated with undulant fever, not Salmonella typhi.
• Remittent fever: Remittent fever is a symptom seen in various infectious diseases and is not specific to Salmonella typhi.
• Dengue fever: Dengue fever is caused by the dengue virus, not Salmonella typhi.

Answer: A

Salmonella paratyphi A is the most common strain of Salmonella paratyphi causing enteric fever (paratyphoid fever) in India.

Incorrect Options:

• B: While Salmonella paratyphi B exists, Salmonella paratyphi A is more commonly associated with enteric fever in India.
• C: There is no specific subtype labeled as Salmonella paratyphi C in the context of enteric fever in India.

Answer: Bacteraemia in first week

Enteric fever (typhoid fever) is characterized by bacteremia in the first week of infection. The causative agent, Salmonella typhi, enters the bloodstream and disseminates to various organs, leading to systemic symptoms.

The other options are incorrect:

• Carrier in 90%: Not everyone who gets infected with Salmonella typhi becomes a carrier. Carriage rates can vary, and carriers can develop in a smaller percentage of cases.
• All serotypes cause the disease: Enteric fever is primarily caused by Salmonella typhi, and not all serotypes of Salmonella lead to enteric fever. Different serotypes of Salmonella can cause various types of infections.
• Rosy spots on the 18th day: Rose spots, which are small, pink, and blanching lesions, can appear on the abdomen, but they typically appear around the second week of illness, not specifically on the 18th day.

Answer: Meningitis

Escherichia coli (E. coli) is commonly associated with various infections. However, it is not a common cause of meningitis. Meningitis is more frequently caused by other bacteria such as Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae.

The other options are incorrect:

• Urinary tract infections: E. coli is a common cause of urinary tract infections (UTIs), particularly in the lower urinary tract.
• Septic infections of wounds: E. coli can cause septic infections, including those in wounds, especially if there is contamination with fecal material.
• Diarrhoea: Certain pathogenic strains of E. coli can cause diarrheal illnesses, including enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), and enterohemorrhagic E. coli (EHEC).
• Dysentery: Some strains of E. coli, such as enteroinvasive E. coli (EIEC), can cause dysentery-like symptoms.

Answer: Corynebacterium diphtheriae

Diphtheria is caused by the bacterium Corynebacterium diphtheriae. This bacterium is responsible for producing a toxin that can lead to the characteristic symptoms of diphtheria, including the formation of a pseudomembrane in the throat and respiratory difficulties.

The other options are incorrect:

• C. Bovis: Corynebacterium bovis is a species of bacteria, but it is not the causative agent of diphtheria.
• C. Jeikeium: Corynebacterium jeikeium is another species of bacteria, but it is not associated with diphtheria.
• C. equi: Corynebacterium equi is a bacterium that primarily affects horses and is not the causative agent of diphtheria in humans.

Answer: Klebs and Loeffler

The causative organism of diphtheria, Corynebacterium diphtheriae, was first demonstrated by Friedrich Loeffler and Paul Frosch in 1884. Loeffler, along with Albert Calmette, subsequently isolated the diphtheria bacillus in pure culture. Klebs and Loeffler worked together on the identification of the bacterium during their research.

The other options are incorrect:

• Robert Koch: Robert Koch is a renowned microbiologist known for his contributions to the development of Koch’s postulates and his work on the etiology of infectious diseases. However, he was not directly involved in the initial identification of the diphtheria bacillus.
• Louis Pasteur: Louis Pasteur, another notable microbiologist, made significant contributions to the field of microbiology and vaccination. However, he was not involved in the initial discovery of the diphtheria bacillus.
• Volhard and Fahr: Volhard and Fahr were not involved in the initial demonstration of the causative organism of diphtheria.

Answer: Gram positive

Corynebacterium is a genus of bacteria, and most species within this genus are Gram-positive. Gram staining is a method used to differentiate bacterial species into two groups based on the characteristics of their cell walls. In the case of Corynebacterium diphtheriae, the causative agent of diphtheria, it is Gram-positive.

The other options are incorrect:

• Resistant to Penicillin: The sensitivity or resistance of bacteria to antibiotics can vary, but being Gram-positive or Gram-negative is not directly related to resistance to specific antibiotics like penicillin.
• Gram-negative: Corynebacterium is generally classified as Gram-positive.
• Resistant to Chloramphenicol: Similar to the first incorrect option, resistance to chloramphenicol is not a characteristic associated with being Gram-positive.

Answer: Polymeta phosphate granules

Corynebacterium diphtheriae, the bacterium responsible for causing diphtheria, is known to contain polymeta phosphate granules. These granules are intracellular inclusions consisting of polyphosphate.

The other options are incorrect:

• Starch granules: Bacteria, in general, do not store energy in the form of starch granules. Starch storage is more characteristic of plant cells.
• Lipid granules: Lipid granules are not a typical storage form found in Corynebacterium diphtheriae.

Answer: Upto 2 weeks

The incubation period of diphtheria, the time from exposure to the bacterium (Corynebacterium diphtheriae) to the onset of symptoms, is typically up to 2 weeks. During this period, the bacteria colonize the respiratory tract and produce the diphtheria toxin.

The other options are incorrect:

• Upto 1 week: The incubation period is generally longer than 1 week.
• 2–4 weeks: While the onset of symptoms can occur within 2 weeks, the upper limit of the typical incubation period is not usually 4 weeks.

Answer: Eleck’s gel precipitation test

The Elek test, also known as Eleck’s gel precipitation test, is used for the virulence testing of Corynebacterium diphtheriae. It involves placing a filter paper strip impregnated with diphtheria antitoxin on a gel containing live diphtheria bacilli. If the test is positive, a line of precipitation (known as Elek’s line) will form, indicating the production of diphtheria toxin by the bacterial strain.

The other options are incorrect:

• Ascoli’s thermoprecipitation test: This test is not specifically used for the virulence testing of C. diphtheriae.
• C.R.P test: C.R.P. stands for C-reactive protein, and it is a blood test used to detect inflammation in the body, not for diphtheria virulence testing.
• M.R.T. test: There is no widely recognized test for diphtheria virulence known as M.R.T. test.

Answer: Formalin

Diphtheria toxoid is prepared by treating the diphtheria toxin with formalin (a solution of formaldehyde in water). This treatment with formalin inactivates the toxin, converting it into toxoid. Toxoids are modified toxins that have lost their toxic properties but retain their ability to stimulate the immune system. Diptheria toxoid is a key component in the diphtheria vaccine.

The other options are incorrect:

• Aldehyde: Formalin is a type of aldehyde, and it is specifically used in the preparation of diphtheria toxoid.
• Phenols: Phenols are not typically used in the preparation of diphtheria toxoid. Formalin (formaldehyde) is the more common agent for this purpose.

Answer: Toxaemia

Diphtheria is an example of toxaemia. Toxaemia refers to the presence of toxins in the bloodstream, leading to systemic effects. In the case of diphtheria, the disease is caused by the bacterium Corynebacterium diphtheriae, which produces a potent exotoxin. The diphtheria toxin is responsible for the characteristic symptoms of the disease, and its effects are systemic, causing damage to various organs.

The other options are incorrect:

• Bacteraemia: Bacteraemia is the presence of bacteria in the bloodstream. While Corynebacterium diphtheriae can be present in the respiratory tract, the primary manifestation of diphtheria is due to the effects of the toxin rather than the bacteria circulating in the blood.
• Pyaemia: Pyaemia is a condition characterized by the presence of pus-forming organisms in the bloodstream, leading to the formation of multiple abscesses. Diphtheria is not typically associated with this type of infection.
• Septicaemia: Septicaemia is a condition involving the presence and multiplication of bacteria in the blood. Diphtheria is more accurately described as toxaemia, where the toxin produced by the bacteria is a major contributor to the disease.

Answer: Tubercle formation

11The main symptom of tuberculosis (TB) is the formation of characteristic lesions called tubercles. Tubercles are small, rounded nodules or masses that develop in tissues, particularly in the lungs in the case of pulmonary tuberculosis. These lesions are composed of immune cells, primarily macrophages, surrounded by a wall of fibrous tissue. The presence of tubercles is a hallmark of TB infection.

The other options are incorrect:

• Liquid formation is a symptom of tuberculosis, but it is not the main symptom. Tuberculosis is primarily characterized by the formation of tubercles.
• Tubercle formation and liquid formation are both symptoms of tuberculosis, but they are not always present in all cases. In some cases, tuberculosis can cause symptoms without the formation of tubercles or the production of pus.

Answer: Tuberculosis

BCG (Bacillus Calmette-Guérin) vaccine is used for the prevention of tuberculosis (TB). It is an attenuated strain of Mycobacterium bovis, a bacterium related to Mycobacterium tuberculosis, which causes TB in humans. BCG vaccination is commonly administered in many countries as a part of routine childhood immunization programs to protect against severe forms of TB, particularly in young children.

The other options are incorrect:

• Brucellosis: BCG vaccine is not intended for the prevention of brucellosis. Brucellosis is caused by bacteria of the genus Brucella.
• Diphtheria: BCG vaccine is not designed to prevent diphtheria. Diphtheria is caused by Corynebacterium diphtheriae.
• Botulism: BCG vaccine does not provide protection against botulism. Botulism is caused by toxins produced by Clostridium botulinum.

Answer: 0.05 ml

The typical dose of BCG (Bacillus Calmette-Guérin) vaccine is approximately 0.05 ml. The vaccine is administered intradermally (into the skin) usually on the upper arm. It is important to note that the exact dosage may vary based on the specific formulation of the vaccine used and the recommendations of the healthcare provider or public health program.

The other options are incorrect:

• 0.2–0.5 ml: This is not the standard dose for BCG vaccine. The usual dose is smaller, around 0.05 ml.
• 0.1 ml: The standard dose of BCG vaccine is typically smaller than 0.1 ml.
• 0.2 to 0.3 ml: While this range is closer to the correct dose, the standard dose is generally around 0.05 ml.

Answer: Bovine tubercle bacilli

The Bacillus Calmette-Guérin (BCG) vaccine contains avirulent strains of bovine tubercle bacilli. These strains have been attenuated, meaning that they have been weakened so that they cannot cause disease in humans. However, they are still able to stimulate the immune system to produce antibodies and other immune cells that can protect against infection with Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB).

The other options are incorrect:

• Human tubercle bacilli are the strains of Mycobacterium tuberculosis that cause TB in humans. They are not used in the BCG vaccine.
• Avian tubercle bacilli are the strains of Mycobacterium tuberculosis that cause TB in birds. They are also not used in the BCG vaccine.
• Atypical mycobacteria are a group of bacteria that are closely related to Mycobacterium tuberculosis, but they do not cause TB. They are also not used in the BCG vaccine.

Answer: Both Refampicin, Isoniazid and Pyrazinamide, Streptomycin

The standard treatment for tuberculosis (TB) often involves a combination of drugs to ensure effectiveness and reduce the risk of resistance. The combination therapy typically includes drugs such as Rifampicin and Isoniazid, and in some cases, Pyrazinamide and Streptomycin. This combination is designed to target different aspects of the tuberculosis bacteria and improve treatment outcomes.

The other options are incorrect:

• Rifampicin, Isoniazid: While these drugs are commonly used in the treatment of TB, the standard regimen often includes a combination of drugs.
• Pyrazinamide, Streptomycin: Similarly, this combination is part of the standard treatment regimen for TB, but it is not used alone. Combination therapy is preferred to prevent resistance and improve efficacy.

Answer: Tuberculous cavity of the lung

The greatest number of tubercle bacilli is present in tuberculous cavities of the lung. This is because tuberculous cavities are areas of lung tissue that have been destroyed by the bacteria that cause tuberculosis, Mycobacterium tuberculosis. The bacteria can multiply freely in these cavities, which can lead to the release of large numbers of bacilli into the air.

The other options are incorrect:

• Large sized tuberculomas are solid masses of tissue that are formed by the accumulation of inflammatory cells in response to the Mycobacterium tuberculosis bacteria. While tuberculomas can contain a large number of bacteria, they are not as numerous as the bacilli found in tuberculous cavities.
• Miliary tuberculosis is a severe form of tuberculosis in which the bacteria spread throughout the body, including the lungs, liver, spleen, and lymph nodes. While miliary tuberculosis can involve a large number of organs, the overall number of bacteria in the body may not be as high as in a case of cavitary tuberculosis.
• Tuberculous lymphadinitis is an inflammation of the lymph nodes that is caused by Mycobacterium tuberculosis bacteria. While tuberculous lymphadinitis can involve a large number of lymph nodes, the overall number of bacteria in the body may not be as high as in a case of cavitary tuberculosis.

Answer: Lepronmetous leprosy

Histoid Hansen is a rare variant of lepromatous leprosy. In lepromatous leprosy, the skin lesions contain a large number of bacteria (Mycobacterium leprae) and there is a lack of effective cell-mediated immune response against the bacteria. The histoid variant is characterized by nodular lesions that resemble histiocytes and have a dense concentration of bacilli. It is a distinctive form within the lepromatous spectrum of leprosy.

The other options are incorrect:

• Tuberculoid Leprosy: Tuberculoid leprosy is characterized by well-demarcated skin lesions, with few or no bacteria present. It represents a form of leprosy with a stronger cell-mediated immune response.
• Borderline tuberculoid: Borderline tuberculoid leprosy is an intermediate form between tuberculoid and lepromatous leprosy, with moderate cell-mediated immune response and some bacilli present.
• Borderline lepromatous: Borderline lepromatous leprosy is another intermediate form, but it has more bacterial presence compared to borderline tuberculoid and less than lepromatous leprosy.

Answer: Stre. pyogens

Scarlet fever is caused by Streptococcus pyogenes, also known as Group A Streptococcus (GAS). It is characterized by a red rash that gives the skin a sunburned appearance and is often associated with a sore throat and fever.

Incorrect Options:

Staphylococcus aureus: Staphylococcus aureus is not the causative agent of scarlet fever. However, it can cause other skin infections and conditions.
Streptococcus viridans: Streptococcus viridans is not associated with scarlet fever. It is commonly found in the oral cavity and can cause dental and endocardial infections.

Answer: Str. pyogenes

Rheumatic fever is most commonly caused by an infection with Streptococcus pyogenes (Group A Streptococcus), particularly strains that produce certain toxins. This bacterial infection is often associated with pharyngitis (strep throat). Rheumatic fever can occur as a complication of inadequately treated streptococcal infections.

The other options are incorrect:

• Streptococcus viridans: Streptococcus viridans is not commonly associated with rheumatic fever. It is often found in the oral cavity and is not a typical cause of rheumatic fever.
• Staphylococcus aureus: Staphylococcus aureus is not the primary cause of rheumatic fever. Rheumatic fever is more commonly associated with Streptococcus pyogenes infections.

Answer: Scarlet fever

Penicillin is the drug of choice for treating infections caused by Streptococcus pyogenes, the bacterium responsible for scarlet fever. Penicillin is effective against this bacterium and is commonly used to treat streptococcal infections.

The other options are incorrect:

• Whooping cough: The drug of choice for whooping cough (pertussis) is macrolide antibiotics such as azithromycin or clarithromycin.
• Brucellosis: The drug of choice for brucellosis is a combination of antibiotics such as doxycycline and rifampin.
• Cholera: The drug of choice for cholera is antibiotics such as tetracycline or doxycycline, along with rehydration therapy. Penicillin is not typically used for cholera treatment.

Answer: Pneumomnia

Streptococcus pneumoniae is a common cause of pneumonia in human beings. It is a bacterium that can infect the respiratory tract, leading to conditions such as pneumonia.

The other options are incorrect:

• Septicaemia: While Streptococcus pneumoniae can cause systemic infections, including bacteremia (presence of bacteria in the blood), it is not the primary cause of septicaemia.
• Paronychia: Paronychia is a localized infection around the nail, and Streptococcus pneumoniae is not a typical cause of this condition.

Answer: Capsular polysaccharide

The major virulence factor for Streptococcus pneumoniae is its capsular polysaccharide. The capsule protects the bacterium from phagocytosis by host immune cells, allowing it to evade the host’s defenses and establish infection.

The other options are incorrect:

• Specific soluble substance: This is not a specific virulence factor associated with Streptococcus pneumoniae.
• Vi-antigen: The Vi antigen is associated with Salmonella Typhi, the causative agent of typhoid fever, not Streptococcus pneumoniae.
• Forssman antigen: Forssman antigen is a glycolipid antigen found in some animal tissues and is not a virulence factor for Streptococcus pneumoniae.

Answer: None of these

Conjunctivitis in a newborn can be caused by various microorganisms, including bacteria, viruses, and other pathogens. The specific causative agent would depend on the circumstances and clinical presentation. It’s not exclusively caused by Streptococcus, Pneumococcus, or Meningococci. Common pathogens associated with neonatal conjunctivitis include Chlamydia trachomatis and Neisseria gonorrhoeae.

The other options are incorrect:

• Streptococcus: While Streptococcus species can cause infections, they are not a specific cause of neonatal conjunctivitis.
• Pneumococcus: Streptococcus pneumoniae (pneumococcus) can cause infections, but it is not a typical cause of neonatal conjunctivitis.
• Meningococci: Neisseria meningitidis (meningococci) is known for causing meningitis and septicemia but is not a typical cause of neonatal conjunctivitis.

Answer: Orthomyxoviridae

Influenza viruses belong to the family Orthomyxoviridae. The Orthomyxoviridae family includes several genera of viruses, but influenza viruses are the most well-known members. They are responsible for causing influenza or flu in humans and other animals.

The other options are incorrect:

• Retroviridae: Retroviridae is a different family of viruses. Retroviruses, such as HIV, belong to the Retroviridae family, not influenza viruses.

Answer: Eight segments of RNA

Influenza viruses are unique among viruses in that their genome consists of eight segments of single-stranded RNA. These segments encode different viral proteins, allowing for genetic reassortment when two different influenza viruses infect the same host cell. This capability contributes to the antigenic variability of influenza viruses.

The other options are incorrect:

• Two strands of RNA: Influenza viruses have a segmented, single-stranded RNA genome, not two strands.
• Single RNA: While influenza viruses have a single-stranded RNA genome, it is divided into eight segments rather than being a single continuous strand.

Answer: Influenza

Reye’s syndrome is a rare but serious condition that primarily affects children and teenagers recovering from a viral infection, particularly influenza (flu) or chickenpox. The exact cause is not well understood, but the use of aspirin during a viral illness, especially in children, has been associated with an increased risk of Reye’s syndrome.

The other options are incorrect:

• St. pneumoniae: Streptococcus pneumoniae is a bacterium, and Reye’s syndrome is not caused by bacterial infections.
• St. pyogenes: Streptococcus pyogenes is also a bacterium and is not associated with Reye’s syndrome.

Answer: Rubella / 3day measles

German measles is another name for rubella, and it is also known as “3-day measles.” This viral infection is caused by the rubella virus and is characterized by a mild rash, fever, and swollen lymph nodes. The name “3-day measles” refers to the relatively short duration of the rash.

The other options are incorrect:

• Rubella / 2-day measles: The more commonly used term is “3-day measles.”
• Rubella / 4-day measles: The more commonly used term is “3-day measles.”
• Rubella / 1-day measles: The more commonly used term is “3-day measles.”

Answer: Congential rubella

The commonest cause of rubella in newborns is congenital rubella, which occurs when a pregnant woman contracts rubella (German measles) during the first trimester of pregnancy. Congenital rubella can lead to serious birth defects in the baby, known as congenital rubella syndrome (CRS). The virus can affect the developing fetus, causing a range of abnormalities such as heart defects, hearing loss, and vision problems.

The other options are incorrect:

• Postnatal rubella: Rubella contracted after birth is not a common cause of complications in newborns.
• Expanded rubella syndrome (ERS): The correct term is congenital rubella syndrome (CRS), not expanded rubella syndrome.

Answer: Paramyxoviriae

The mumps virus belongs to the family Paramyxoviridae. Paramyxoviruses are a family of RNA viruses that includes several important human and animal pathogens. The mumps virus is responsible for causing mumps, a contagious viral infection characterized by swelling of the salivary glands, especially the parotid glands.

The other options are incorrect:

• Retroviridae: Retroviruses are a different family of viruses that include human immunodeficiency virus (HIV).
• Orthomyxoviridae: The influenza virus, which causes influenza (flu), belongs to the family Orthomyxoviridae, not the mumps virus.

Answer: Koplik’s spots

Measles is characterized by the presence of Koplik’s spots, which are small, white spots with bluish-white centers on the mucous membranes inside the mouth. These spots are often seen on the buccal mucosa (inner lining of the cheeks) and are considered a diagnostic feature of measles.

The other options are incorrect:

• Negribodies: Negribodies are eosinophilic cytoplasmic inclusions that are characteristic of rabies virus infections.
• Babes-Ernest granules: This term is not associated with measles. Babes-Ernst granules are associated with the causative agent of Q fever (Coxiella burnetii).
• Fever: While fever is a common symptom of measles, it is not a specific characteristic used for diagnosis. Koplik’s spots are more specific to measles diagnosis.

Answer: Brucellosis

Brucellosis is a bacterial infection caused by the bacteria of the genus Brucella. It is a zoonotic disease, meaning that it is transmitted from animals to humans. Brucella bacteria are commonly found in cattle, sheep, goats, pigs, and dogs. Humans can become infected with brucellosis by consuming contaminated food or water, or by direct contact with infected animals.

The other options are incorrect:

• Pertussis is a bacterial infection caused by Bordetella pertussis. It is also known as whooping cough.
• Plague is a bacterial infection caused by Yersinia pestis. It is also known as the black death.

Answer: Brucella

Mediterranean fever, also known as familial Mediterranean fever (FMF), is not caused by Brucella. It is an autosomal recessive genetic disorder characterized by recurrent episodes of fever and inflammation of the abdominal lining, joints, and lungs. The condition is associated with mutations in the MEFV gene.

The other options are incorrect:

• M. tuberculosis: Mycobacterium tuberculosis is the bacterium responsible for causing tuberculosis.
• S. typhi: Salmonella typhi is the bacterium that causes typhoid fever.
• C. neoformans: Cryptococcus neoformans is a fungus responsible for cryptococcosis.

Answer: Castaneda strip

Among the given options, the most specific test for Brucellosis is Castaneda strip. It is a skin test that measures the delayed-type hypersensitivity reaction to Brucella antigens. It is highly specific, meaning that it rarely produces a false-positive result. However, it is not as sensitive as other tests, meaning that it may not detect all cases of Brucellosis.

The other options are incorrect:

• Frei test is a skin test that measures the delayed-type hypersensitivity reaction to a protein extract from lymphogranuloma venereum (LGV) bacteria. It is not specific for Brucellosis, as it can also be positive in people with other infections, such as syphilis and chlamydia.
• Weil test is a test that measures the presence of antibodies to Brucella bacteria. It is not as specific as the Castaneda strip, as it can also be positive in people who have been vaccinated against Brucellosis or who have had a past infection with the bacteria.
• Rose water test is a test that measures the presence of antibodies to Brucella bacteria. It is not as specific as the Castaneda strip, as it can also be positive in people who have been vaccinated against Brucellosis or who have had a past infection with the bacteria.

Answer: Anthrax

Malignant pustule is a severe form of cutaneous anthrax, caused by Bacillus anthracis, a bacterium that produces spores that can be found in soil, animal products, and contaminated water. When spores enter the body through a break in the skin, they germinate and produce toxins that can cause severe local infection, leading to the formation of a large, painful, and often fatal lesion known as a malignant pustule.

The other options are incorrect:

• Tetanus is a bacterial infection caused by Clostridium tetani, a bacterium that produces spores that can be found in soil and dust. Tetanus typically causes muscle spasms and stiffness, but it does not cause skin lesions.
• Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae, a bacterium that produces a toxin that can damage the heart and nervous system. Diphtheria can also cause skin lesions, but these are not typically malignant pustules.

Answer: Cutaneous

Cutaneous anthrax is the most common form of anthrax in humans. It occurs when the spores of Bacillus anthracis come into contact with the skin, leading to the development of skin lesions, ulcers, and the characteristic black eschar (scab) in the center. Cutaneous anthrax is usually acquired through direct contact with infected animals or their products.

The other options are incorrect:

• Alimentary: Alimentary anthrax is associated with the ingestion of contaminated meat and is less common in comparison to cutaneous anthrax.
• Pulmonary: Pulmonary anthrax is a more severe form of the disease that results from inhaling spores. It is less common than cutaneous anthrax.
• Hepatic: Hepatic anthrax is not a recognized form of anthrax in humans. Anthrax primarily manifests as cutaneous, pulmonary, or gastrointestinal forms in humans.

Answer: All of these

Sheep, cattle, and goats are all herbivores that graze in pastures that may be contaminated with anthrax spores. These animals ingest the spores while grazing, and the spores can germinate in the intestines, leading to anthrax infection.

Anthrax is a disease caused by the bacterium Bacillus anthracis, which forms spores that can survive in soil for many years. These spores can be ingested by grazing animals, such as sheep, cattle, and goats, and can also enter the body through cuts or abrasions in the skin.

When animals become infected with anthrax, they can develop a variety of symptoms, including fever, weakness, and swelling of the lymph nodes. The infection can also lead to death.

Answer: Rhbdo virus

The virus that causes rabies is a member of the Rhabdoviridae family, which is a group of viruses that are characterized by their bullet-shaped morphology. The Rhabdoviridae family includes three genera: Lyssavirus, Vesiculovirus, and Ephemerovirus. The virus that causes rabies is a member of the Lyssavirus genus.

The other options are incorrect:

• Orthomyxovirus is a family of viruses that includes influenza virus.
• Paramyxovirus is a family of viruses that includes measles virus, mumps virus, and respiratory syncytial virus.
• Toga virus is a family of viruses that includes dengue virus, chikungunya virus, and Zika virus.

Answer: Rhabdo viridae

Rhabdoviruses are a family of negative-sense RNA viruses that includes the rabies virus. They are characterized by their bullet-shaped morphology and their ability to cause a variety of diseases in animals and humans.

The other options are incorrect:

• Toga viridae is a family of viruses that includes the dengue virus, chikungunya virus, and Zika virus.
• Paramyxo viridae is a family of viruses that includes the measles virus, mumps virus, and respiratory syncytial virus.

Answer: Street virus

The rabies virus isolated from natural human or animal infection is termed as a Street virus. Street virus is a term used to refer to the virus as it exists in nature. It is typically more virulent and less easily attenuated than fixed virus, which is a virus that has been adapted to laboratory conditions.

The other options are incorrect:

• Fixed virus: This term is not used in the context of rabies virus isolation.
• Both Street virus and Fixed virus: The term “Fixed virus” is not applicable to rabies virus.