Microbiology Lecture Flashcards

Comprehensive vocabulary flashcards covering general bacteriology, parasitology, virology, clinical microbiology, and sterilization methods based on the lecture notes.

Gram +ve cocci staining

Appear violet under microscopic examination.

Gram -ve cocci staining

Appear pink under microscopic examination.

HLOF test

Hugh & Leifson oxidative Fermentative test used to differentiate Micrococcus (oxidative) from Staphylococcus (fermentative).

Peptidoglycan layer

A thick heteropolysaccharide layer ($16-80\,nm$) in Gram +ve bacteria made of alternating N-acetyl muramic acid (NAM) and N-acetyl glucosamine (NAG).

Teichoic Acid

Polymers of ribitol present in large amounts in the Gram +ve cell wall but absent in Gram -ve cell walls.

Lipopolysaccharide (LPS)

A component of the Gram -ve outer membrane consisting of three parts: Lipid A (endotoxic), Core polysaccharide, and O-antigen (serogrouping).

Braun's lipoprotein

The molecule that firmly attaches the outer membrane to the peptidoglycan layer in Gram -ve bacteria.

Slime layer

A glyocalyx outside the cell wall that is not well-organized and can be easily washed off.

Monotrichous

A flagella arrangement consisting of a single flagellum, such as in $Vibrio\,cholerae$ or $Pseudomonas$.

Peritrichous

A flagella arrangement where flagella are distributed all over the cell surface, such as in $E.\,coli$, $Proteus$, and $Salmonella$.

Flagellin protein

The protein that makes up the longest portion of the flagella, known as the filament.

Darting motility

A sudden, rapid movement characteristic of $Vibrio\,cholerae$.

Swarming motility

A type of motility characteristic of $Proteus$ species.

Common pili

Hair-like thin appendages that help in bacterial adhesion and are present in many numbers.

Sex pili

Thin appendages (1-10 in number) found only in Gram-negative bacteria ($GNB$) that help in conjugation.

Bacterial Spore Structure

Consists of several layers: the Core (containing DNA), Cortex (containing calcium deposition for resistance), Coat, and Exosporium.

Lag phase

The phase between inoculation and the beginning of bacterial multiplication, where size is maximum due to enzyme accumulation.

Log phase

The phase of exponential division and a straight line in the growth curve, which is the preferred phase for Gram staining.

Direct saline wet mount

A microscopic examination method used to maintain the morphology of cysts and eggs and visualize the motility of trophozoites.

Iodine wet mount

A microscopic examination method using Lugol's iodine to visualize nuclear details of protozoan cysts and helminthic eggs.

Inclusion body

Aggregates of viral proteins found in the cytoplasm (acidophilic) or nucleus (basophilic) of host cells.

Interferons (IFNs)

Proteinous or glycoprotein substances released from virus-infected cells that inhibit host cell protein synthesis and indirectly inhibit viral infection in nearby cells.

Halophilic vibrios

Vibrios that cannot grow without salt and have an optimum growth at $7\%$ salt concentration, such as $Vibrio\,parahemolyticus$.

Cholera Toxin Fragment A

Causes ADP ribosylation of G-protein, leading to increased adenylyl cyclase activity and increased $cAMP$.

String test (+ve)

When a colony of $Vibrio\,cholerae$ mixed with $0.5\%$ sodium deoxycholate becomes mucoid and forms a string when lifted.

E. histolytica Trophozoite

The active, invasive stage ($15-20\,\mu m$) containing a small, central karyosome and RBC inclusions.

HBsAg

Hepatitis B surface antigen; the first marker to elevate in serum, indicating the onset of HBV infection.

Window Period (HIV)

A 3–12 week interval after entry when HIV antibodies are not yet detectable, requiring detection via $4^{th}$ Gen ELISA or $RT-PCR$.

Hypnozoites

Dormant forms of $P.\,vivax$ and $P.\,ovale$ that remain in hepatocytes for years and cause malarial relapse.

Black Water Fever

A complication of falciparum malaria characterized by severe intravascular hemolysis, fever, and dark-colored urine (hemoglobinuria).

LD bodies

Leishman Donovan bodies; intra-cytoplasmic, non-flagellated amastigotes found within macrophages in Visceral Leishmaniasis.

Protein A

A virulence factor of $Staphylococcus\,aureus$ that inhibits opsonization and is responsible for co-agglutination.

mecA gene

The gene responsible for methicillin resistance in $MRSA$ by altering penicillin-binding protein to $PBP-2a$.

CAMP test

The Christie-Atkins-Munch-Peterson test showing arrowhead-shaped hemolysis used to identify Group B Streptococcus ($S.\,agalactiae$).

Virchow's lepra cells

Foamy cells in Leprosy containing macrophages filled with cigar-like bundles of bacilli known as globi.

McFadyean's reaction

A staining method for $Bacillus\,anthracis$ where the capsule appears purple surrounding blue bacilli using polychrome methylene blue.

Nagler's reaction

A toxigenicity test for $Clostridium\,perfringens$ that detects $\alpha$-toxin (lecithinase activity) via opalescence on egg yolk agar.

Koplik's spots

Characteristic white spots surrounded by erythema on the buccal mucosa near the lower ${2}^{nd}$ molar, diagnostic for Measles.

Lowenstein-Jensen (LJ) medium

A selective medium for $Mycobacterium\,tuberculosis$ containing malachite green, asparagine, mineral salts, and eggs.

Significant bacteriuria

A colony count of $>10^5\,CFU/ml$ in urine, indicating a urinary tract infection ($UTI$).

VDRL test

Venereal Disease Research Laboratory test; a non-specific slide flocculation test detecting reagin antibodies for Syphilis screening.

Tetanospasmin

An exotoxin produced by $Clostridium\,tetani$ that inhibits the release of $GABA$, leading to spastic paralysis and muscle spasms.