Which bacteria is a common cause of bacterial meningitis?

Correct Answer: D

Rationale: The correct answer is D: All of the above. Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae are all common causes of bacterial meningitis. Neisseria meningitidis is often associated with outbreaks in community settings. Streptococcus pneumoniae is a leading cause of bacterial meningitis in adults. Haemophilus influenzae used to be a common cause in children before the introduction of the Hib vaccine. Therefore, since all three bacteria are known to cause bacterial meningitis, the correct answer is D. Choices A, B, and C are incorrect because each bacteria individually can cause bacterial meningitis, making "All of the above" the correct comprehensive answer.

Correct Answer: A

Rationale: The correct answer is A: 4 and 250. Coli index is calculated by dividing the number of red colonies by the volume of water analyzed, which gives 2 red colonies / 500 ml = 4. Coli titer is the reciprocal of the coli index, so it is 1 / 4 = 250. This indicates the concentration of coliform bacteria in the water sample. Choices B, C, and D are incorrect as they do not follow the correct calculation steps for determining the coli index and coli titer. B has the correct coli index but incorrect coli titer. C and D have the values reversed, leading to incorrect results.

Correct Answer: B

Rationale: The correct answer is B: Yersinia enterocolitica. Y. enterocolitica is known to cause gastroenteritis and diarrhea in humans. It is often associated with contaminated food or water. Bordetella pertussis causes whooping cough, not diarrhea. Corynebacterium diphtheria causes respiratory diphtheria. Neisseria meningitidis is associated with meningitis and septicemia, not diarrhea. Therefore, based on the patient's symptoms and history, Y. enterocolitica is the most likely cause of the diarrhea in this case.

Correct Answer: A

Rationale: The correct answer is A: Treponema. Treponema pallidum is a spirochete bacterium that appears as long, thin, and spiral-shaped microorganisms with 8-12 regular coils under the microscope. This characteristic morphology is specific to Treponema species, making it the correct choice. Borrelia, Leptospira, and Vibrios have different shapes and arrangements under the microscope, making them incorrect choices in this scenario.

Correct Answer: B

Rationale: The correct answer is B because collecting specimens from the surface of a wound does not provide adequate samples for anaerobic agent detection. Anaerobic agents thrive in deep tissue environments with low oxygen levels, making surface specimens unreliable. Tissue samples and aspirations (choice A) are superior for diagnosing skin infections. Excessive production of toxins, not skin rash (choice C), causes symptoms in some infections. While healthy skin provides some protection, it is not completely impenetrable to microorganisms (choice D).

Correct Answer: B

Rationale: The correct answer is B: placenta. The placenta is a highly specialized structure that forms during pregnancy and serves as a barrier, protecting the fetus from harmful microorganisms that could potentially harm the developing baby. It facilitates the exchange of nutrients, oxygen, and waste between the mother and fetus while preventing the passage of most bacteria and viruses. The uterus (A) is the organ where the fetus develops, but it does not have the specific protective functions of the placenta. The vagina (C) is the birth canal and does not provide protection from microorganisms for the fetus. The mammary gland (D) is responsible for producing milk after birth and is not directly involved in protecting the fetus from microorganisms during pregnancy.

Correct Answer: A

Rationale: The correct answer is A: Blood. Toxoplasmosis is diagnosed through serological tests that detect specific antibodies in the blood. These antibodies indicate exposure to the Toxoplasma gondii parasite. Feces, urine, and duodenal contents are not typically used for diagnosing toxoplasmosis as the parasite is not commonly found in these samples. Blood is the primary material used as it provides the necessary antibodies for accurate diagnosis.

Correct Answer: D

Rationale: The correct answer is D because Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum are all known to cause non-gonococcal urethritis and cervicitis. These organisms can infect the urogenital tract and lead to inflammation and symptoms in both males and females. Each of these bacteria has been identified as a common cause of these conditions through research and clinical studies. Therefore, since all three organisms are capable of causing non-gonococcal urethritis and cervicitis, the correct answer is D. The other choices (A, B, and C) are incorrect because each of them alone can cause these conditions, making option D the most comprehensive and accurate choice.

Correct Answer: A

Rationale: Rationale: 1. Thin, pale pink microorganisms with spiral coils suggest Treponema pallidum, the causative agent of syphilis. 2. Staining with Romanovsky-Giemsa method highlights the characteristic morphology of T. pallidum. 3. Syphilis presents with various stages and symptoms, correlating with the lymph node involvement. 4. Leptospirosis is caused by Leptospira interrogans, presenting with different clinical features. 5. Relapsing fever is caused by Borrelia species, which do not match the description. 6. Trypanosomiasis is caused by Trypanosoma species, which have distinct morphology and staining properties.