MICR 210: Medical Microbiology 1 Flashcards

Comprehensive vocabulary flashcards covering Gram staining, antimicrobial susceptibility testing, Gram-positive and Gram-negative bacteria, anaerobes, uncommon organisms, mycology, parasitology, and virology.

Culture Gram Smear

A microscopic smear prepared from bacterial colonies growing on solid or liquid culture media after incubation, evaluated under $100\times$ oil immersion magnification without quantitation.

Direct Gram Smear

A microscopic smear prepared directly from a patient specimen to assess sample quality by quantitating SECs and PMNs under $10\times$ low power field magnification and identifying microorganisms under $100\times$ oil immersion magnification.

Polymorphonuclear White Blood Cells (PMNs)

Infection-fighting host cells quantified under $10\times$ low power field magnification; their presence indicates a purulent sample, and their quantity is generally proportional to infection severity.

Squamous Epithelial Cells (SECs)

Cells lining the skin, mouth, and urogenital tract quantified under $10\times$ low power field magnification; their presence indicates superficial contamination and is inversely proportional to specimen quality.

Minimum Inhibitory Concentration (MIC)

The lowest concentration of an antimicrobial agent that effectively inhibits visible growth of a bacterial isolate in vitro.

Bacteriostatic Agent

An antimicrobial agent that inhibits further bacterial replication and growth by inactivating the microorganism without causing direct cell death.

Bactericidal Agent

An antimicrobial agent that causes direct destruction and death of targeted bacterial cells.

D-Zone Test

A modified Kirby-Bauer disk diffusion assay using erythromycin and clindamycin disks placed $15\text{--}26\,mm$ apart to detect inducible clindamycin resistance in staphylococci.

Extended Spectrum Beta-Lactamases (ESBLs)

Enzymes produced by certain Gram-negative bacteria (such as Escherichia coli and Klebsiella species) that confer resistance to penicillins, first, second, and third-generation cephalosporins, and monobactams.

Micrococcus species

Aerobic Gram-positive cocci arranged in tetrads that are normal skin flora, catalase-positive, and microdase-positive.

Staphylococcus aureus

Gram-positive cocci in clusters that are catalase-positive, bound coagulase-positive, and free coagulase-positive, capable of producing beta-hemolytic colonies.

Streptolysin O

An oxygen-labile, antigenic hemolysin produced mainly by Group A streptococci that induces anti-streptolysin O titers (ASOT) in host serum.

Streptolysin S

An oxygen-stable, acid-inactivated hemolysin produced by Group A streptococci that is primarily responsible for the large zone of beta-hemolysis on blood agar.

Aerotolerance Testing

A procedure using chocolate agar incubated in CO2 and vitamin K blood agar incubated anaerobically to determine whether a bacterial isolate is an aerobe, facultative anaerobe, or obligate anaerobe.

Reverse CAMP Test

A diagnostic test for presumptive identification of Clostridium perfringens, indicated by an arrowhead-shaped zone of enhanced beta-hemolysis when grown perpendicular to Streptococcus agalactiae.

Nagler Test

A test detecting lecithinase (alpha toxin) activity of Clostridium perfringens on egg yolk agar, demonstrated by an opaque halo of precipitation where anti-alpha toxin is absent.

Serpentine Cording

A snake-like arrangement of Mycobacterium tuberculosis cells observed on acid-fast stains, caused by the presence of cord factor in the cell wall.

Mycoplasmataceae

A family of cell wall-deficient bacteria ranging from $0.3$ to 1.0\,̠m in diameter that cannot be visualized with a Gram stain or treated using beta-lactams.

Erythema Migrans

The characteristic bull's-eye rash that appears at the site of a tick bite during early localized Lyme disease caused by Borrelia burgdorferi.

Germ Tube

An extension or outpouching from a yeast cell without constriction at its base, used for presumptive identification of Candida albicans complex.

Chlamydospores

Thick-walled, round resting spores formed at the terminal ends of hyphae on cornmeal agar, characteristic of Candida albicans complex.

Dimorphic Fungi

Fungi that exist in a unicellular yeast form at body temperature ($37^\circ\text{C}$) and in a multicellular mold form at room temperature ($28\text{--}30^\circ\text{C}$).

Enterobius vermicularis

An intestinal nematode (pinworm) whose adult females migrate nocturnally to the perianal region to deposit thick-walled, football-shaped ova with one flattened side.

Giardia duodenalis

A pathogenic flagellate protozoan causing Giardiasis, featuring binucleated pear-shaped trophozoites with falling-leaf motility and four-nucleated oval cysts.

Cytopathic Effect (CPE)

Distinct morphological and structural changes produced in cultured host cells as a result of viral infection and replication.

Prions

Infectious misfolded proteins lacking a nucleic acid genome that induce misfolding of normal host proteins, causing fatal neurodegenerative diseases such as Creutzfeldt-Jakob disease.

Umbrella Motility

A characteristic inverted umbrella-shaped growth pattern produced near the top of a semi-solid motility tube by Listeria monocytogenes when incubated at room temperature.