A patient undergoing chemotherapy develops a cough. Acid-fast stain of his sputum shows rods and slightly longer forms, with some branching; they vary in their acid fast reaction from one area of the slide to the next. The acid-fast stain was performed by an experienced medical technologist and, when redone, showed the same variation. The growth was done aerobically. What is the most likely agent?
A patient who had surgery to put in a pacemaker and who states he felt fine for the first 3 months now presents 4 months postoperatively with complaints of malaise and increasing fatigue. He is running a low-grade fever, tires easily, and has worsening heart murmurs. Which of the following staphylococcal organisms causes subacute bacterial endocarditis that generally occurs 3 months or more after heart surgery?
A patient who is diabetic and has been in the hospital twice in the last six months presents with a boil on his neck. You drain it, but because of his hospitalizations you realize that there is a good chance that it could be a drug-resistant strain and order direct Gram stain cultures, as well as susceptibility testing and anaerobic culture. The preliminary report comes back with Gram-negative cocci in clusters. This puzzles you, so you call the lab supervisor who realizes the stain was done by a new lab person. It turns out to be Staphylococcus aureus.What mistake in the Gram stain did the new person most likely make to produce pink cocci with no hint of purple?
A patient whose primary source of protein is smoked and cooked fish develops what seems to be pernicious anemia. What parasite is known for causing a similar vitamin B12 deficiency in specific genetically predisposed infected individuals?
A patient presents with explosive, watery, noninflammatory diarrhea along with headache, abdominal cramps, nausea, vomiting, and fever. Symptoms began the day after consuming raw oysters in August. What is the most probable causative agent?
A patient presents with paranasal swelling and bloody exudate from both his eyes and nares, and he is nearly comatose. Necrotic tissue in the nasal turbinates show nonseptate hyphae consistent with Rhizopus, Mucor, or Absidia (phylum Zygomycota, class Phycomycetes). What is the most likely compromising condition underlying this infection?
A patient in their late 30s has splotchy hypopigmentation on the chest and back with only slight itchiness. What is most likely to be seen on a KOH mount of the skin scraping?
A patient in their late 40s with a persistent cough for several weeks but no fever presents radiological signs of a coin lesion. Upon needle biopsy, large, broad-based budding yeasts with a very thick cell wall are observed, with the majority of the yeasts being extracellular. What is the most probable diagnosis?
A noncompliant, human immunodeficiency virus (HIV)-positive patient has been experiencing a stiff neck and a severe headache. The headache was initially relieved by painkillers, but the painkillers are no longer providing relief. His current CD4+ count is 180/mm3. He is not taking any preventive medications. What is the most probable causative agent?
A novel class of pathogen emerges, leading to pneumonia. This pathogen seems to be a budding yeast like organism with chitin in its cell wall. However, unlike typical eukaryotic organisms, it lacks a membrane-bound nucleus and possesses prokaryotic protein synthetic equipment. Among the following antimicrobial agents, which one is most likely to be effective?