Which of the following bacteria is responsible for causing the disease known as pneumonia?

Correct Answer: D

Rationale: Rationale: 1. Streptococcus pneumoniae is a common cause of bacterial pneumonia. 2. Mycobacterium tuberculosis can cause a type of pneumonia called tuberculosis. 3. Escherichia coli is not typically associated with pneumonia. 4. "All of the above" includes both Streptococcus pneumoniae and Mycobacterium tuberculosis, which are known to cause pneumonia. Therefore, D is the correct answer.

Correct Answer: B

Rationale: The correct answer is B: Malarial plasmodiums. The description of crescent bodies with a pointed end, blue cytoplasm, and red nucleus corresponds to the characteristics of Plasmodium species seen in Romanovsky's stain. Plasmodium species are known to cause malaria and have distinct features like the ones described. Incorrect choices: A: Toxoplasmas - Toxoplasma gondii typically appear as tachyzoites or bradyzoites under staining, not crescent bodies. C: Dermotropic leishmania - Leishmania species appear as amastigotes in tissue smears, not crescent bodies. D: Viscerotropic leishmania - Similar to choice C, Leishmania species do not typically present as crescent bodies in stained specimens.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. P. aeruginosa is a Gram-negative rod that is oxidase-positive and lactose non-fermenting. The positive oxidase test indicates the presence of cytochrome c oxidase, a characteristic of P. aerugin. E. coli is lactose fermenting. Salmonella and Shigella are also Gram-negative rods, but they are lactose fermenters, unlike the lactose non-fermenting P. aeruginosa.

Correct Answer: A

Rationale: The correct answer is A: Head lice. Epidemic typhus is transmitted by the body louse, Pediculus humanus humanus, which is different from the head louse, Pediculus humanus capitis. Head lice are not known to transmit epidemic typhus. Body lice are the primary vectors for transmitting epidemic typhus. Fleas are vectors for other diseases such as plague, not epidemic typhus. Ticks are vectors for various diseases but not for epidemic typhus. Therefore, the correct vector for epidemic typhus transmission is body lice, making choice A the correct answer.

Correct Answer: A

Rationale: The most likely diagnosis is A: Botulism. The symptoms, such as nausea, vomiting after eating canned vegetables, dry mucous membranes, muscular hypotonia, anisocoria, mydriasis, dysphagia, and dysarthria, are classic signs of botulism poisoning. Botulism is caused by the neurotoxin produced by Clostridium botulinum bacteria found in improperly canned or preserved food. The neurotoxin affects the nervous system, leading to symptoms like those described. Shigellosis (B), Salmonellosis (C), and Cholera (D) typically present with different symptoms such as diarrhea, fever, and abdominal pain, which are not seen in this patient.

Correct Answer: C

Rationale: The correct answer is Shigella (Choice C) because it matches the description of being Gram-negative rods and lactose non-fermenters. Shigella is a non-lactose fermenting, Gram-negative rod that typically produces colorless colonies on Endo agar. Salmonella (Choice A) and Escherichia coli (Choice B) are both lactose fermenters and would produce pink colonies on Endo agar. Proteus (Choice D) is also a lactose fermenter and would appear pink on Endo agar. Therefore, based on the characteristics provided, Shigella is the most likely microorganism in this scenario.

Correct Answer: A

Rationale: The correct answer is A: destruction of the local blood supply. In osteomyelitis, the infection occurs in the bone, which has a relatively poor blood supply compared to soft tissues. This limited blood flow makes it challenging for antibiotics to reach the infection site effectively, hindering their ability to combat the infection. Destruction of the local blood supply restricts the delivery of antibiotics and immune cells to the infected bone, leading to poor treatment outcomes. Summary: - Option A is correct because the limited blood supply in bones hinders antibiotic delivery. - Option B is incorrect as denaturing by normal flora does not impact antibiotic reach to the infection site. - Option C is incorrect as inflammation and edema, while present, do not primarily hinder antibiotic delivery. - Option D is incorrect as excessive pus production does not directly impede antibiotic access to the infection site.

Correct Answer: A

Rationale: Rheumatic fever is caused by untreated strep throat. Step 1: Strep throat is caused by Streptococcus bacteria. Step 2: If strep throat is not treated with antibiotics, it may lead to rheumatic fever due to the body's immune response attacking its own tissues. Summary: Gangrene, brucellosis, and tularemia are not associated with rheumatic fever.

Correct Answer: A

Rationale: The correct answer is A: Vibrios. Vibrios are gram-negative curved bacteria that are motile and do not form spores or capsules. The description of the bacteria in the question fits the characteristics of Vibrios. Vibrios are commonly found in aquatic environments and some species can cause gastrointestinal infections in humans. B: Spirochetes are also gram-negative curved bacteria, but they are spiral-shaped and have unique axial filaments for motility. The description in the question does not match the characteristics of spirochetes. C: Clostridia are gram-positive, spore-forming bacteria. The question specifically states that the bacteria are gram-negative and do not form spores, ruling out Clostridia. D: Corynebacteria are gram-positive, non-spore-forming bacteria. The description in the question does not match the characteristics of Corynebacteria.