Microbiology Examination Questions

Microbiology Examination Questions

Serology and Diagnostic Tests

• Serology using complement fixation is used to obtain laboratory confirmation of M. pneumoniae infection.
• Direct fluorescent antibody testing on urethral and cervical specimens is used to diagnose genital infections.
• Nucleic acid amplification methods are used to diagnose infections such as syphilis.
• Enzyme immunoassays performed on genital tract specimens are used to diagnose infections such as chlamydia.

Identification of Microorganisms

• Charcoal is present in buffered charcoal yeast extract agar to act as a detoxifying agent for the growth of L. pneumophilia.
• Definitive identification of an anaerobe is likely best accomplished by cell wall fatty acid analysis using gas liquid chromatography.
• A useful test to differentiate M. catarrhalis from saprophytic neisseriae in respiratory samples is the Gram-stain morphology.

Microbiology Questions

• Eubacteria that lack cell walls and do not synthesize the precursors of peptidoglycan are called Mycoplasmas.
• Most microorganisms pathogenic for humans grow best in the laboratory when cultures are incubated at 30-37°C.
• Anaerobes are not usually found in clean catch midstream urine samples.
• A minimum of 10^4 CFU/mL of an organism must be present in a clean catch midstream urine sample to be considered indicative of an infection.

Microbiology Questions Continued

Pathogenesis of Cholera Diarrhea

• The first complex compound of causing Cholera diarrhea is cholera toxin, which causes an increase in cyclic AMP, leading to secretion of chloride and water into the intestinal lumen.
• The pathogenesis of Cholera diarrhea involves the ingestion of contaminated food or water, followed by the colonization of the small intestine by V. cholerae, and the production of cholera toxin.

Types of Anthrax

• There are three types of Anthrax: Pulmonary, Cutaneous, and Intestinal.

Salmonella Growth

• Salmonella grows on Xylose-lysine desoxycholate agar and can ferment glucose, mannitol, and sucrose.

Enterobacteriaceae

• The types of antigens in Enterobacteriaceae are O, K, and H antigens.
• E. coli secrets two types of toxin: heat labile and heat stable.

Klebsiella

• Klebsiella has K antigens.

Lactobacillus

• Lactobacillus ferments sugars to produce lactic acid.

Serratia

• Serratia can cause endocarditis, diarrhea, and septicemia.

Microbiology Questions Continued

Metabolic Pathways

• Metabolic pathways are regulated by enzymes, which are proteins that catalyze specific chemical reactions.
• Extracellular proteins are secreted from the cytoplasmic membrane.

Antibiotics

• Aminoglycosides antibiotics have an extended spectrum and are used to treat Gram-negative infections.
• The phenylanine deamination test indicator is used in the detection of phenylalanine deaminase.
• The antibacterial susceptibility determinant is determined through the disc diffusion test.

Fungal Pathogens

• Histoplasma capsulatum is a fungal pathogen with a dimorphic shape.
• Trichophyton rubrum is a fungal pathogen that causes Tinea corporis.
• Candida albicans has adhesins as one of its virulence factors.
• Aspergillus fumigatus is a systemic fungus.
• Fluconazole is an antifungal drug.

Hemopoiesis and Anemia

• Hemoglobin in blood leaving the lungs is about 98-99% saturated with oxygen, achieving an oxygen delivery between 950 and 1150 ml/min to the body.
• Sites of hemopoiesis in infants occur in the yolk sac.
• Aplastic Anemia is caused by toxic substances, such as pesticides, arsenic, and benzene.
• Some iron is stored in the phagocytic as ferritin and hemosiderin.
• Hypoxia occurs in patients who ascend to high altitude.

Enzymes and Bacterial Growth

• The enzymes that do not need water for reactions are isomerases.
• The important nutrient for bacterial techoic acid is PO4.
• The bacterial group that cannot grow at less than 55°C is thermophile.
• The metabolic pathway used by bacteria but not used by eukaryotes is the Entner-Doudoroff pathway.
• The storage inclusions are carboxysomes.

Antibiotics and Inhibitors

• All of the following are true regarding penicillins EXCEPT that they don't require dosage adjustment in renal failure.
• All of the following inhibit nucleic acid synthesis EXCEPT sulfasalazine.
• Concerning toxicity of antibiotics, enamel dysplasia is common with aminoglycosides, and Grey Baby Syndrome occurs with rifampicin use.
• Which of the following is considered to be bacteriostatic? Chloramphenicol.
• All of the following are true regarding metronidazole EXCEPT that it is useful against trichomonas vaginalis.
• Which among the following antibiotics function as protein synthesis inhibitors? Tetracycline.

Note: The above notes are summarized in a concise and organized manner, focusing on key facts and concepts in microbiology.