Microbiology Test: Questions And Answers

The PAP test, also known as a Pap smear, is a screening test used to detect abnormal cells in the cervix, which can be an early sign of cervical cancer. Human papillomavirus (HPV) is a common sexually transmitted infection that can cause cervical cancer. Therefore, the PAP test is useful in diagnosing infections caused by HPV.

The TPHA test is used to confirm the presence of syphilis, a sexually transmitted infection caused by the bacterium Treponema pallidum. If the TPHA test confirms the suspected infection, it means that the person has developed syphilis. Syphilis can cause various symptoms and complications if left untreated, including the development of a painless sore called a chancre, which is one of the early signs of the infection. Therefore, the correct answer is syphilis.

The correct answer is Rotavirus. Rotavirus is a dsRNA virus that is known to cause gastroenteritis in children. It is a common cause of diarrhea and vomiting, especially in young children. The presence of the dsRNA virus in the stool samples of the diseased children, as revealed by the Immunochromatography assay (ICA), indicates that the etiological agent responsible for the outbreak is Rotavirus.

Escherichia coli is the most likely causative agent of this urinary tract infection (UTI) based on the given information. E. coli is a Gram-negative, facultative anaerobic, motile, and lactose-positive rod-shaped bacterium commonly found in the gastrointestinal tract. It is the most common cause of UTIs, particularly in women. The presence of E. coli in the urine sample suggests that it has migrated from the gastrointestinal tract to the urinary tract, causing the infection.

The presence of acid-fast bacteria in the sputum suggests a possible diagnosis of tuberculosis (TB). TB is a chronic infectious disease caused by Mycobacterium tuberculosis, which requires a long treatment duration to ensure complete eradication of the bacteria. The standard treatment for drug-susceptible TB involves a combination of multiple antibiotics taken for a minimum of 6 months to effectively kill the bacteria and prevent the development of drug resistance. Hence, the correct answer is 6 months.

The presence of blue-green pus, cellulitis, and a swab culture revealing Jasmin smelling greenish colonies suggests an infection caused by Pseudomonas aeruginosa. Pseudomonas aeruginosa is a Gram-negative rod-shaped bacterium commonly associated with burn wound infections. It produces a characteristic blue-green pigment called pyocyanin, which gives the pus its color. Additionally, Pseudomonas aeruginosa has a distinct fruity or grape-like odor, which is described as Jasmin smelling in this case. Hence, Pseudomonas aeruginosa is the most likely species causing the worsening of the burn wound.

The TPHA test is a diagnostic test used to confirm the presence of syphilis infection. If the test confirms the infection, the recommended treatment is beta-lactam antibiotics. Beta-lactam antibiotics are effective against the bacteria that causes syphilis, Treponema pallidum. They work by interfering with the formation of the bacterial cell wall, leading to the death of the bacteria. Examples of beta-lactam antibiotics commonly used to treat syphilis include penicillin and ceftriaxone.

Treponema pallidum is the most probable species causing the infection in the 46-year-old sexually active woman. Treponema pallidum is a long spiral bacteria that is responsible for causing syphilis, a sexually transmitted infection. Given the patient's age, sexual activity, and the nature of the infection, syphilis caused by Treponema pallidum is the most likely explanation.

The correct answer is gram-positive diplococci. Gram-positive diplococci are the most likely bacteria to be seen under the microscope in a case of pneumonia caused by alpha-haemolytic and optochin-sensitive bacteria. This is because certain bacteria, such as Streptococcus pneumoniae, are known to cause pneumonia and appear as gram-positive diplococci when stained with the Gram stain.

Gonorrhea is most often asymptomatic in women. This means that women infected with gonorrhea may not experience any noticeable symptoms, making it difficult to detect and treat the infection. As a result, the infection can go unnoticed and untreated, leading to potential complications such as pelvic inflammatory disease, infertility, and increased risk of HIV transmission. Regular screenings and practicing safe sex are important for sexually active women to prevent the spread of gonorrhea.

If the female newborn presents with infectious conjunctivitis, the most probable cause is gonorrhea. Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae. It can be passed from an infected mother to her newborn during childbirth, resulting in conjunctivitis in the newborn. Other options such as meningococcemia, bacterial vaginosis, syphilis, and GBS pneumonia are not commonly associated with infectious conjunctivitis in newborns.

Vibrio cholerae colonies will be large and yellow after 24 hours of incubation at 37 degrees Celsius on the Thiosulfate-Citrate-Bile Salts-Sucrose (TCBS) Agar because this specific agar is selective for Vibrio species. TCBS agar contains thiosulfate, citrate, bile salts, and sucrose, which inhibit the growth of most other bacteria except for Vibrio species. Vibrio cholerae is a species of Vibrio that causes cholera, and it is known to produce large and yellow colonies on TCBS agar due to its ability to ferment sucrose.

Shiga toxin is the correct answer because it is known to cause vascular damage in the colon, kidneys, and central nervous system. This damage can lead to conditions such as hemorrhagic colitis or a more severe condition called hemolytic uremic syndrome.

The most likely cause of the infant's infection is Streptococcus agalactiae. This is indicated by the description of the colonies on the mother's vaginal-rectal swab culture, which showed glistening grey-white colonies with a narrow zone of beta-hemolysin on Columbia Agar. Streptococcus agalactiae is known to cause infections in newborns, especially those delivered prematurely, and it matches the Gram(+), catalase (-) cocci identified in the infant's blood culture.

The common cold is most often caused by the rhinovirus. Rhinoviruses are a group of viruses that infect the upper respiratory tract and are responsible for causing the majority of common cold cases. They are highly contagious and can spread through respiratory droplets when an infected person coughs or sneezes. Rhinovirus infections typically result in symptoms such as a runny or stuffy nose, sore throat, cough, and mild body aches. While other viruses like Sars-Cov-1, Sars-CoV-2, and influenza virus can also cause respiratory illnesses, the rhinovirus is the most common culprit for the common cold.

The most likely pathogen responsible for the 7-year old's otitis media is Streptococcus pneumoniae. This is indicated by the presence of Gram-positive, encapsulated, alpha-hemolytic, and optochin-sensitive cocci in the culture. Streptococcus pneumoniae is a common cause of otitis media, especially in children.

The correct answer is "Gram-negative rods". This is because the question states that the culture was positive for Acinetobacter baumannii, which is a type of bacteria that belongs to the Gram-negative group. Gram-negative bacteria have a different cell wall structure compared to Gram-positive bacteria, and they stain pink or red in the Gram staining technique. Gram-negative rods are a common cause of infections, especially in hospital settings, and they often exhibit antibiotic resistance.

The correct answer is RNA. Bornholm disease is caused by the Coxsackie B virus, which is an RNA virus. RNA viruses have RNA as their genetic material, instead of DNA. This virus specifically belongs to the Enterovirus genus of the Picornaviridae family, which are all RNA viruses. The symptoms described, such as fever, headache, and muscle pain, are characteristic of Bornholm disease, which is commonly caused by Coxsackie B virus infection.

Beta-haemolysin is a virulence factor that plays an important role in the pathogenesis of infections caused by S. aureus. It is a toxin produced by the bacteria that causes the destruction of red blood cells and damages host tissues. This toxin helps the bacteria to evade the immune system and establish infection. It also contributes to the spread of the bacteria within the host and the progression of the infection. Therefore, beta-haemolysin is a critical factor in the pathogenicity of S. aureus infections.

Proteus mirabillis is a UTI pathogen that often leads to kidney stone formation. This bacterium is known for its ability to produce urease, an enzyme that breaks down urea into ammonia and carbon dioxide. The ammonia produced by Proteus mirabillis raises the pH of urine, creating an alkaline environment that promotes the formation of struvite and calcium phosphate stones. These stones can obstruct the urinary tract and lead to kidney stone formation.

The presence of blood, nitrites, and bacteria in the urine suggests a urinary tract infection (UTI). Gram-negative lactose-negative rods are commonly associated with UTIs, and Proteus penneri is a known pathogen that fits this description. Therefore, Proteus penneri is the most likely pathogen causing the kidney stones and UTI in this patient.

Debridement, penicillin G, clindamycin, metronidazole, and hyperbaric oxygen may be used in the treatment of infections caused by Clostridium perfringens. This bacterium is responsible for causing gas gangrene, a severe infection that can lead to tissue death. Debridement is the process of removing dead tissue to promote healing. Penicillin G, clindamycin, and metronidazole are antibiotics that can effectively target and kill Clostridium perfringens. Hyperbaric oxygen therapy involves breathing pure oxygen in a pressurized chamber, which helps to increase oxygen levels in the tissues and inhibit the growth of anaerobic bacteria like Clostridium perfringens.

EAEC (Enteroaggregative E. coli) is the correct answer. EAEC colonizes the intestinal mucosa by using aggregative adherence fimbriae (AAF), which helps them adhere to the intestinal lining. They also form a mucoid biofilm, which provides protection and helps them establish a persistent infection. Additionally, EAEC produces various enterotoxins and cytotoxins, which contribute to the pathogenesis of diarrhea. ETEC (Enterotoxigenic E. coli) produces heat-labile and heat-stable enterotoxins, EHEC (Enterohemorrhagic E. coli) produces Shiga toxins, EPEC (Enteropathogenic E. coli) forms attaching and effacing lesions, and EIEC (Enteroinvasive E. coli) invades and replicates within intestinal epithelial cells.

Lipid A is the correct answer because the presence of acid-fast bacteria suggests a possible infection with Mycobacterium tuberculosis, which is known to have a cell wall containing Lipid A. Lipid A is a component of lipopolysaccharides (LPS) found in Gram-negative bacteria, including Mycobacterium tuberculosis. This component is responsible for the endotoxic activity of LPS, causing symptoms such as weight loss, abdominal pain, and diarrhea. The other options, such as sulfatides, antigen H, antigen O, and protein A, are not typically associated with acid-fast bacteria or the symptoms described.

Campylobacter jejuni is the common cause of bacterial gastroenteritis and is considered a major triggering agent of Guillain-Barre Syndrome (GBS). GBS is a rare neurological disorder where the body's immune system mistakenly attacks the peripheral nerves. Campylobacter jejuni infection is one of the most common preceding infections associated with GBS. It is often contracted through contaminated food, especially undercooked poultry, unpasteurized milk, and contaminated water. Symptoms of Campylobacter jejuni infection include diarrhea, abdominal pain, fever, and vomiting. GBS can develop a few weeks after the initial infection and can cause muscle weakness, paralysis, and potentially life-threatening complications.

Penicillins may be administered as a treatment for the sexually transmitted bacterial infection caused by the obligatory intracellular parasite in the 27-year-old woman. Penicillins are a class of antibiotics that are effective against a wide range of bacterial infections, including those caused by obligate intracellular parasites. They work by inhibiting the synthesis of the bacterial cell wall, leading to the destruction of the bacteria. Penicillins are commonly used to treat various sexually transmitted infections, making them a suitable choice in this scenario.

Linezolid is the correct answer for the treatment of the infection in this case. The patient's wound worsened, pus appeared, and cellulitis was observed, indicating a bacterial infection. The culture revealed small colonies on Coccosel agar, and under the microscope, Gram(+) cocci were observed. Sensitivity tests revealed that the bacteria were VRE (Vancomycin-resistant enterococci) and HLAR (high-level aminoglycoside-resistant). Linezolid is an antibiotic that is effective against VRE and can be used to treat infections caused by these bacteria. Vancomycin, Teicoplanin, Streptomycin, and Gentamicin are not effective against VRE.

The given symptoms of slow onset of infection, rhinorrhea, weak throat pain with redness of the mucous membranes, and a fever lower than 38.5 celsius are characteristic of pharyngitis caused by adenovirus. Adenovirus is a common cause of respiratory infections, including pharyngitis, and it typically presents with these symptoms. Corynebacterium diphtheriae is unlikely as it causes a more severe form of pharyngitis with a grayish-white membrane covering the throat. Streptococcus pyogenes can cause similar symptoms but typically presents with a higher fever and more severe throat pain. Influenza virus primarily causes respiratory symptoms and systemic symptoms like fever, body aches, and fatigue. Staphylococcus aureus is not a common cause of pharyngitis.

EAEC, or Enteroaggregative E. coli, is the correct answer. EAEC causes diarrhea by producing heat-stable (ST) and/or heat-labile (LT) enterotoxins, which are plasmid-encoded. This pathotype of E. coli is characterized by the formation of a stacked-brick pattern on the surface of intestinal cells, and it is commonly associated with persistent diarrhea in children and travelers.