1.
Neonatal meningitis is most commonly transmitted by
Correct Answer
D. Exposure in birth canal
Explanation
Neonatal meningitis is most commonly transmitted through exposure in the birth canal. During childbirth, the baby can come into contact with bacteria or viruses present in the mother's birth canal, leading to an infection in the baby's central nervous system. This mode of transmission is one of the primary ways in which neonatal meningitis occurs.
2.
Production of a neurotoxin that binds to target sites on spinal cord neurons responsible for inhibiting skeletal muscle contraction is a characteristic of
Correct Answer
D. Clostridium tetani
Explanation
Clostridium tetani produces a neurotoxin that binds to target sites on spinal cord neurons responsible for inhibiting skeletal muscle contraction. This neurotoxin, called tetanospasmin, blocks the release of inhibitory neurotransmitters, leading to uncontrolled muscle contractions and the development of tetanus. The other options, Clostridium botulinum, Clostridium perfringens, and Clostridium difficile, do not produce this specific neurotoxin and are associated with different diseases or conditions. Therefore, the correct answer is Clostridium tetani.
3.
Which of the following provides the eye with its best defense against microorganisms?
Correct Answer
D. Tears
Explanation
Tears provide the eye with its best defense against microorganisms because they contain lysozyme, an enzyme that has antibacterial properties. When tears are produced, they help to wash away any foreign particles or microorganisms that may come into contact with the eye, preventing infection. Additionally, tears also contain other immune components such as antibodies and antimicrobial proteins that further enhance the eye's defense against microorganisms.
4.
Gp120 binds to
Correct Answer
D. CD4
Explanation
gp120 is a glycoprotein found on the surface of HIV virus that is responsible for binding to the CD4 receptor on the surface of T-helper cells. This binding is crucial for the virus to enter the host cell and initiate the infection. Therefore, the correct answer is CD4.
5.
A diagnosis of tuberculosis involves
Correct Answer
E. All of the choices are correct
Explanation
The correct answer is "All of the choices are correct" because a diagnosis of tuberculosis typically involves multiple tests and examinations. A chest X-ray is commonly used to detect abnormalities in the lungs that may indicate tuberculosis. Acid-fast stain of sputum is performed to identify the presence of Mycobacterium tuberculosis, the bacteria that causes tuberculosis. Sputum culture is used to confirm the presence of the bacteria and determine its drug susceptibility. The tuberculin skin test is used to assess a person's immune response to tuberculosis. Therefore, all of these choices are correct when it comes to diagnosing tuberculosis.
6.
Reactivation of chickenpox is called
Correct Answer
A. Shingles
Explanation
Shingles is the correct answer because it refers to the reactivation of the chickenpox virus, also known as herpes zoster. Shingles is characterized by a painful rash that typically appears in a band or strip on one side of the body. While pneumonia is a respiratory infection and exanthems are a general term for rash or skin eruptions, they are not specific to the reactivation of chickenpox. Therefore, shingles is the most accurate term for the reactivation of chickenpox.
7.
Which is not correct about Mycobacterium species?
Correct Answer
A. All species are human pathogens
Explanation
The statement "All species are human pathogens" is not correct about Mycobacterium species. While some species of Mycobacterium can cause diseases in humans, not all species are human pathogens. Some species are harmless and can be found in the environment. Therefore, it is incorrect to say that all species of Mycobacterium are human pathogens.
8.
"Rice water stools" are associated with disease caused by this organism
Correct Answer
C. Vibrio cholerae
Explanation
"Rice water stools" are a characteristic symptom of cholera, a disease caused by Vibrio cholerae. Cholera is an acute diarrheal illness that results in the production of large amounts of watery stools that resemble rice water in appearance. Vibrio cholerae is a bacterium that infects the small intestine and produces a toxin that leads to the excessive secretion of water and electrolytes, resulting in the characteristic rice water stools.
9.
Which of the following organisms causes urinary tract infections?
Correct Answer
A. Proteus mirabilis
Explanation
Proteus mirabilis is a bacterium that is known to cause urinary tract infections (UTIs). It is a common cause of UTIs, particularly in individuals with underlying urinary tract abnormalities or catheterization. Proteus mirabilis is a gram-negative bacterium that can colonize and infect the urethra, bladder, and kidneys, leading to symptoms such as frequent urination, burning sensation during urination, and lower abdominal pain. It is important to identify and treat infections caused by Proteus mirabilis promptly to prevent complications and recurrence.
10.
One virulence factor of Mycobacterium leprae is the ability to live inside
Correct Answer
D. MacropHages
Explanation
Mycobacterium leprae, the bacterium that causes leprosy, has the ability to live inside macrophages. Macrophages are immune cells that play a crucial role in engulfing and destroying pathogens. However, Mycobacterium leprae can evade the immune system by residing within macrophages, allowing it to persist and cause infection. This ability to survive inside macrophages is a significant virulence factor of the bacterium, as it enables it to evade immune responses and establish a chronic infection.
11.
Lyme disease is transmitted by
Correct Answer
E. Ticks
Explanation
Lyme disease is primarily transmitted by ticks. Ticks are small arachnids that attach themselves to the skin of animals or humans and feed on their blood. When an infected tick bites a person, it can transmit the bacteria that cause Lyme disease into their bloodstream. This is why it is important to take precautions, such as wearing protective clothing and using insect repellent, when in areas where ticks are known to be prevalent.
12.
Impetigo is caused by
Correct Answer
E. Both stapH. aureus and strep. pyogenes
Explanation
Impetigo is a highly contagious skin infection that is commonly caused by both Staphylococcus aureus and Streptococcus pyogenes. These bacteria can enter the body through cuts, abrasions, or insect bites, leading to the development of small blisters or sores on the skin. The infection spreads easily through direct contact with the affected person or contaminated objects. Both Staphylococcus aureus and Streptococcus pyogenes produce toxins that contribute to the characteristic symptoms of impetigo, such as redness, itching, and the formation of a yellowish crust. Treatment typically involves topical or oral antibiotics to eliminate the bacterial infection.
13.
Production of enterotoxin is a characteristic of
Correct Answer
C. Clostridium difficile
Explanation
Clostridium difficile is a bacterium that is known to produce enterotoxin. Enterotoxins are toxins that affect the intestines and cause symptoms such as diarrhea and abdominal pain. Clostridium difficile is a common cause of healthcare-associated infections, particularly in individuals who have been treated with antibiotics. It is responsible for a condition called Clostridium difficile infection (CDI), which can range from mild diarrhea to severe inflammation of the colon. Therefore, the production of enterotoxin is a characteristic of Clostridium difficile.
14.
Production of a neurotoxin that prevents acetylcholine release from motor neurons at neuromuscular junctions is a characteristic of
Correct Answer
A. Clostridium botulinum
Explanation
Clostridium botulinum produces a neurotoxin that inhibits the release of acetylcholine from motor neurons at neuromuscular junctions. This neurotoxin is responsible for causing botulism, a serious illness characterized by muscle weakness and paralysis. Clostridium perfringens, Clostridium difficile, and Clostridium tetani are also pathogenic bacteria, but they do not produce the specific neurotoxin that prevents acetylcholine release. Therefore, the correct answer is Clostridium botulinum.
15.
What material in skin cells provides protection from abrasions, water damage and microorganism entry?
Correct Answer
B. Keratin
Explanation
Keratin is a protein found in the outermost layer of the skin, known as the epidermis. It forms a tough, waterproof barrier that protects the skin from abrasions, water damage, and the entry of microorganisms. Keratin also helps to maintain the structural integrity of the skin and prevents it from drying out. This makes it an essential component in providing overall protection to the skin.
16.
The most immediate and important treatment needed to prevent death in cholera victims is
Correct Answer
A. Water and electrolyte replacement
Explanation
The most immediate and important treatment needed to prevent death in cholera victims is water and electrolyte replacement. Cholera is a severe diarrheal disease that causes rapid dehydration and electrolyte imbalances. Replenishing fluids and electrolytes is crucial in preventing death from dehydration and maintaining proper bodily functions. Antimicrobials may be used to treat the underlying infection, but the immediate priority is restoring the body's fluid balance. Antitoxin and surgery are not relevant in the treatment of cholera.
17.
MRSAs are S. aureus strains that are
Correct Answer
C. Resistant to penicillin derivatives
Explanation
MRSAs, or Methicillin-resistant Staphylococcus aureus, are strains of S. aureus bacteria that have developed resistance to penicillin derivatives. This means that they are not affected by the antibiotics that are commonly used to treat infections caused by S. aureus, such as methicillin and other penicillin-based drugs. This resistance is a result of genetic changes in the bacteria that allow them to produce enzymes called beta-lactamases, which break down the antibiotics and render them ineffective. As a result, MRSAs are difficult to treat and can cause severe infections that are resistant to many commonly used antibiotics.
18.
Which chemical, produced by S. aureus is also known as "spreading factor"?
Correct Answer
D. Hyaluronidase
Explanation
Hyaluronidase is a chemical produced by S. aureus that is also known as the "spreading factor". This enzyme helps the bacteria to spread and invade tissues by breaking down hyaluronic acid, a component of connective tissue. This allows the bacteria to move through the tissues and cause infection.
19.
The primary viral cause of chronic diarrhea, globally, is
Correct Answer
B. Rotavirus
Explanation
Rotavirus is the correct answer because it is a primary viral cause of chronic diarrhea worldwide. Rotavirus is highly contagious and commonly affects infants and young children. It is transmitted through the fecal-oral route and can cause severe diarrhea, vomiting, and dehydration. Rotavirus infections are responsible for a significant number of hospitalizations and deaths in children under the age of five, particularly in developing countries with limited access to clean water and sanitation facilities. Vaccination against rotavirus has been successful in reducing the burden of rotavirus-related diarrhea globally.
20.
The normal biota of the CNS consists of
Correct Answer
E. The CNS has no normal biota
Explanation
The central nervous system (CNS) is a highly protected and sterile environment, which means that it does not have a normal biota. This is because the CNS is enclosed within the skull and spinal column, and is surrounded by protective barriers such as the blood-brain barrier. These barriers prevent the entry of microorganisms into the CNS, thereby maintaining its sterility. Therefore, the statement that the CNS has no normal biota is correct.
21.
__________ occurs when bacteria flourish and grow in the blood stream.
Correct Answer
E. Septicemia
Explanation
Septicemia occurs when bacteria flourish and grow in the bloodstream. This condition is characterized by the presence of bacteria in the blood, leading to a systemic infection. It is a severe and potentially life-threatening condition that can result in organ failure and septic shock. Prompt medical intervention is crucial to treat septicemia and prevent further complications.
22.
Which of the following is not true of Ebola and Marburg?
Correct Answer
D. Transmitted by mosquitos
Explanation
Ebola and Marburg are both caused by filoviruses and can disrupt clotting factors in the body. They are transmitted through direct contact with body fluids, such as blood, saliva, and vomit. However, they are not transmitted by mosquitoes. Mosquitoes are not known to be vectors for the transmission of these viruses. Therefore, the statement that they are transmitted by mosquitoes is not true. It is important to note that there is currently no specific treatment for Ebola and Marburg, only supportive care to manage symptoms and prevent complications.
23.
The toxin of Staphylococcus aureus strains that causes blisters and desquamation of skin in scalded skin syndrome is
Correct Answer
D. Exfoliative toxin
Explanation
The correct answer is exfoliative toxin. Exfoliative toxin is produced by certain strains of Staphylococcus aureus and is responsible for causing blisters and desquamation of the skin in scalded skin syndrome. This toxin acts by causing the separation of the epidermis from the underlying dermis, leading to the characteristic symptoms of the disease. Enterotoxin is responsible for causing food poisoning, hemolysin causes destruction of red blood cells, toxic shock syndrome toxin causes toxic shock syndrome, and erythrogenic toxin is responsible for the rash seen in scarlet fever.
24.
Which organism is a common cause of meningitis in AIDS patients and can be found in bird droppings?
Correct Answer
D. Cryptococcus neoformans
Explanation
Cryptococcus neoformans is a common cause of meningitis in AIDS patients and can be found in bird droppings. This organism is a type of fungus that is commonly found in soil and bird droppings, particularly those of pigeons. It can be inhaled and cause infection in individuals with weakened immune systems, such as those with AIDS. Meningitis caused by Cryptococcus neoformans can be life-threatening if not treated promptly.
25.
Retroviruses have the following characteristics except
Correct Answer
B. DNA protein
Explanation
Retroviruses have RNA as their genetic material, not DNA. They use an enzyme called reverse transcriptase to convert their RNA into DNA, which is then integrated into the host genome. Therefore, the statement "DNA protein" is incorrect as it does not accurately describe the characteristics of retroviruses.
26.
Helicobacter pylori appears to have some connection with
Correct Answer
E. Ulcers AND stomach cancer
Explanation
Helicobacter pylori is a type of bacteria that is commonly found in the stomach. It is known to cause ulcers by damaging the lining of the stomach or small intestine. Additionally, it has been linked to an increased risk of stomach cancer. Therefore, the correct answer is ulcers AND stomach cancer, indicating that Helicobacter pylori is associated with both conditions.
27.
Necrotizing fasciitis is
Correct Answer
A. Also called impetigo
28.
All of the following pertain to patients with AIDS except
Correct Answer
E. Highest number of cases worldwide is in the United States
Explanation
Patients with AIDS can have an immunodeficiency, CD4 T-cell titers below 200 cells/mm3 of blood, repeated, life-threatening opportunistic infections, and can develop unusual cancers and neurological disorders. However, the statement that the highest number of cases worldwide is in the United States is not true. This statement is incorrect because the highest number of AIDS cases worldwide is actually in sub-Saharan Africa.
29.
Which drugs interfere with the action of an HIV enzyme needed for final assembly and maturation of the virus?
Correct Answer
B. Protease inhibitors
Explanation
Protease inhibitors interfere with the action of an HIV enzyme needed for the final assembly and maturation of the virus. These drugs inhibit the activity of the protease enzyme, which is responsible for cutting the long HIV protein chains into smaller, functional proteins. By inhibiting this enzyme, protease inhibitors prevent the virus from assembling and maturing into an infectious form. Therefore, protease inhibitors are effective in reducing the replication and spread of HIV in the body.
30.
Which is incorrect about warts?
Correct Answer
D. Are frequently cancerous
31.
Which of the following is not true of bacterial conjunctivitis?
Correct Answer
D. Has a clear discharge
Explanation
Bacterial conjunctivitis is characterized by symptoms such as redness, swelling, and discharge from the eyes. The discharge is typically thick and yellow or green in color, not clear. Therefore, the statement "Has a clear discharge" is not true of bacterial conjunctivitis.
32.
The most common cause of liver cancer in the US is
Correct Answer
C. HCV
Explanation
HCV, or Hepatitis C virus, is the most common cause of liver cancer in the US. Hepatitis C is a viral infection that primarily affects the liver and can lead to chronic liver disease, cirrhosis, and eventually liver cancer. It is transmitted through contact with infected blood, such as through sharing needles or unsafe medical procedures. HCV infection often goes undiagnosed for many years, leading to the development of liver cancer in some cases. Effective treatments for Hepatitis C are available, but early detection and prevention are crucial in reducing the risk of liver cancer.
33.
Which of the following is a sexually transmitted disease?
Correct Answer
B. Trichomoniasis
Explanation
Trichomoniasis is a sexually transmitted disease caused by a parasite called Trichomonas vaginalis. It is mainly transmitted through sexual contact, including vaginal, anal, or oral sex. Symptoms of trichomoniasis include itching, burning, and discharge in the genital area. It can be easily treated with antibiotics. Toxoplasmosis, giardiasis, malaria, and balantidiasis are not sexually transmitted diseases. Toxoplasmosis is caused by a parasite found in cat feces, giardiasis is caused by a parasite found in contaminated food or water, malaria is caused by a parasite transmitted through mosquito bites, and balantidiasis is caused by a parasite found in contaminated food or water.
34.
A frequent cancer that is seen in AIDS patients is
Correct Answer
C. Kaposi's sarcoma
Explanation
Kaposi's sarcoma is a frequent cancer observed in AIDS patients. It is caused by a virus called human herpesvirus 8 (HHV-8), which is more prevalent in individuals with weakened immune systems, such as those with AIDS. Kaposi's sarcoma usually manifests as purple or red lesions on the skin, but it can also affect other organs like the lungs, liver, and gastrointestinal tract. The virus is transmitted through saliva, sexual contact, and blood transfusions. Treatment options include antiretroviral therapy to boost the immune system, chemotherapy, and radiation therapy.
35.
Anthrax is
Correct Answer
E. All of the choices are correct
Explanation
Anthrax is a zoonosis, meaning it can be transmitted from animals to humans. It can be transmitted through contact, inhalation, and ingestion, making it a highly contagious disease. In humans, anthrax can cause a rapidly fatal toxemia and septicemia, leading to severe illness and potentially death. Although anthrax is not commonly seen in the United States, sporadic cases can still occur. Therefore, all of the choices provided are correct explanations of anthrax.
36.
Permanent cardiovascular and neurological damage is seen in which stage of syphilis?
Correct Answer
C. Tertiary
Explanation
In the tertiary stage of syphilis, permanent cardiovascular and neurological damage is seen. This stage occurs when the infection is left untreated for a long time, usually several years after the initial infection. The bacteria have spread throughout the body, causing damage to various organs, including the heart and the nervous system. This can lead to serious complications such as heart disease, stroke, and neurosyphilis, which can result in paralysis, blindness, and dementia. Treatment at this stage can help manage the symptoms but may not reverse the permanent damage already done.
37.
The most common cause of vaginitis is
Correct Answer
A. Candida albicans
Explanation
The most common cause of vaginitis is Candida albicans. This is because Candida albicans is a type of yeast that naturally resides in the vagina. However, when there is an overgrowth of this yeast, it can lead to an infection known as vaginal yeast infection or candidiasis. Factors such as hormonal changes, weakened immune system, antibiotic use, and poor hygiene can contribute to the overgrowth of Candida albicans. Symptoms of vaginitis caused by Candida albicans include itching, burning, and abnormal discharge. Treatment usually involves antifungal medications to eliminate the yeast overgrowth.
38.
About 60% of the bacterial pneumonias that require hospitalization of adults are caused by
Correct Answer
B. S. pneumoniae
Explanation
S. pneumoniae is the correct answer because it is known to be a common cause of bacterial pneumonia in adults requiring hospitalization. It is a pathogenic bacterium that can infect the lungs and lead to pneumonia. The other options, S. pyogenes, S. aureus, and K. pneumonia, are also potential causes of pneumonia, but they are not as commonly associated with hospitalization in adults as S. pneumoniae.
39.
Which of the following is not true of meningoencephalitis?
Correct Answer
C. Causative organisms are viruses
Explanation
Meningoencephalitis is an infection that affects both the brain and the meninges. The causative organisms for meningoencephalitis are typically Naegleria fowleri and Acanthamoeba, which are amoebas, rather than viruses. Therefore, the statement that causative organisms are viruses is not true for meningoencephalitis.
40.
The oily secretion that lubricates the hair follicles of the skin is
Correct Answer
A. Sebum
Explanation
Sebum is the oily secretion produced by the sebaceous glands in the skin. It lubricates the hair follicles, keeping them moisturized and preventing them from becoming dry and brittle. Sebum also helps to protect the skin by forming a barrier against bacteria and other harmful substances. Eczema, suder, and acne are not related to the lubrication of hair follicles.
41.
This new class of drugs will interfere with the virus inserting itself into host DNA:
Correct Answer
C. Fusion inhibitors
Explanation
Fusion inhibitors are a new class of drugs that work by preventing the virus from fusing with the host cell membrane, thus blocking the entry of the virus into the host cell. By inhibiting this fusion process, the virus is unable to insert itself into the host DNA and replicate. This mechanism of action makes fusion inhibitors an effective treatment option for viral infections by interfering with the initial stages of the viral life cycle. Therefore, it is correct to say that fusion inhibitors will interfere with the virus inserting itself into host DNA.
42.
Candida albicans is a
Correct Answer
A. Fungus
Explanation
Candida albicans is a fungus. Fungi are a group of organisms that include yeasts, molds, and mushrooms. Candida albicans is a type of yeast that is commonly found in the human body, particularly in the mouth, throat, and genital area. It can cause infections, such as oral thrush and vaginal yeast infections, especially in individuals with weakened immune systems. Therefore, the correct answer is fungus.
43.
Oral lesions called Koplik's spots are seen in patients with
Correct Answer
D. Measles (rubeola)
Explanation
Koplik's spots are small white spots that appear on the inside of the cheeks and are characteristic of measles (rubeola). They are caused by the measles virus and are typically seen a few days before the onset of the rash. Croup, mumps, influenza, and rubella do not typically present with Koplik's spots, making measles the correct answer.
44.
Hutchinson's teeth are
Correct Answer
D. A symptom of congenital sypHilis
Explanation
Hutchinson's teeth are a symptom of congenital syphilis. Syphilis is a sexually transmitted infection that can be passed from mother to baby during pregnancy. Hutchinson's teeth are a specific dental abnormality that occurs in children with congenital syphilis. These teeth are smaller and more widely spaced than normal, with notched incisors and a characteristic screwdriver-shaped appearance. Therefore, the correct answer is that Hutchinson's teeth are a symptom of congenital syphilis.
45.
The preferred treatment for suspected lyme disease is
Correct Answer
D. Doxycycline
Explanation
Doxycycline is the preferred treatment for suspected Lyme disease because it is effective against the bacteria that causes the disease, Borrelia burgdorferi. It is a broad-spectrum antibiotic that can penetrate tissues well, including the central nervous system where the bacteria may reside. Doxycycline is also well-tolerated and has a good safety profile. It is usually prescribed for a duration of 14 to 21 days, depending on the severity of the infection. Other antibiotics like penicillin, ciprofloxacin, quinine, and chloroquine are not typically used as first-line treatments for Lyme disease.
46.
Symptoms of cryptosporidiosis include
Correct Answer
A. Headache, sweats, vormiting, severe abdominal cramps and diarrhea
Explanation
The correct answer is "Symptoms of cryptosporidiosis include headache, sweats, vomiting, severe abdominal cramps, and diarrhea." This answer accurately describes the symptoms commonly associated with cryptosporidiosis, which is an infection caused by the parasite Cryptosporidium. These symptoms are consistent with the gastrointestinal symptoms typically experienced by individuals with this infection.
47.
Formation of a pseudomembrane in the back of the throat is seen in
Correct Answer
A. DipHtheria
Explanation
The formation of a pseudomembrane in the back of the throat is a characteristic feature of diphtheria. Diphtheria is a highly contagious bacterial infection caused by Corynebacterium diphtheriae. The bacteria release toxins that cause the formation of a grayish-white pseudomembrane in the throat, which can obstruct the airway and lead to severe respiratory distress. This pseudomembrane is a result of the body's immune response to the infection and is composed of dead tissue, bacteria, and immune cells. Prompt diagnosis and treatment with antibiotics and antitoxin are essential to prevent complications and spread of the infection.
48.
What brain defense restricts substances from entering the brain by the vascular system?
Correct Answer
B. Blood-brain barrier
Explanation
The blood-brain barrier is a protective mechanism in the brain that restricts the entry of substances from the vascular system. It is composed of specialized cells that line the blood vessels in the brain, forming a barrier that prevents the passage of harmful substances, toxins, and large molecules into the brain tissue. This barrier plays a crucial role in maintaining the delicate balance of the brain's internal environment and protecting it from potential damage.
49.
The fibrous sac that encloses the heart is the
Correct Answer
D. Pericardium
Explanation
The fibrous sac that encloses the heart is called the pericardium. The pericardium is a double-layered membrane that surrounds the heart and provides protection and support. It consists of an outer fibrous layer and an inner serous layer. The fibrous layer is tough and dense, while the serous layer is smooth and lubricated, allowing the heart to beat and move within the pericardial sac without friction. The pericardium also helps to prevent the heart from overfilling with blood and helps maintain its position within the chest cavity.
50.
The major agents responsible for the common cold are
Correct Answer
B. Rhinoviruses
Explanation
Rhinoviruses are the major agents responsible for the common cold. They are a type of virus that infects the upper respiratory tract, causing symptoms such as a runny or stuffy nose, sore throat, cough, and sneezing. Rhinoviruses are highly contagious and can spread easily from person to person through respiratory droplets. They are most active during the colder months, which is why the common cold is more prevalent during winter. While other viruses like Coxsackie, Influenza, Caliciviruses, and Rotavirus can also cause respiratory illnesses, Rhinoviruses are the most common culprits for the common cold.