Medical Microbiology Notes - MBBS Review

Vocabulary practice flashcards covering key microbiological, dermatological, and infectious disease topics from MBBS study notes.

Toxic Shock Syndrome (TSS)

A rare, life-threatening condition caused by the release of exotoxins (e.g., TSST-1) produced by Staphylococcus aureus or Streptococcus pyogenes, characterized by high fever ($>38.9^\frac{1}{2}\text{C}$ or $>38.9^\top\text{C}$ / $>38.9^\text{o}\text{C}$), hypotension, diffuse sunburn-like macular rash, multi-organ dysfunction, and late-phase desquamation of palms or soles ($1\text{--}2\text{ weeks}$ after onset).

mecA gene

A gene carried by Methicillin-Resistant Staphylococcus aureus (MRSA) that encodes an altered penicillin-binding protein (PBP2a), conferring resistance to beta-lactam antibiotics including methicillin, oxacillin, and cephalosporins.

M protein

The major virulence factor of Streptococcus pyogenes that facilitates adherence to host cells and prevents phagocytosis.

Streptokinase

An enzyme produced by Streptococcus pyogenes that activates plasminogen to plasmin, dissolving fibrin clots to allow bacterial invasion.

Tzanck smear

A simple diagnostic microscopic tool used to examine skin lesions for herpes virus infections (HSV or VZV); collected material stained with Giemsa, Wright, or Papanicolaou stain shows multinucleated giant cells and intranuclear inclusion bodies.

Wood's Lamp Examination

A diagnostic procedure using UV light that causes Microsporum species to fluoresce bright green.

Alpha-toxin (Phospholipase C)

The key exotoxin virulence factor of Clostridium perfringens that causes cell lysis, tissue destruction, and vascular permeability in gas gangrene.

Naegler's reaction

A biochemical lecithinase test used to identify Clostridium perfringens; when grown on egg yolk medium, its lecithinase enzyme breaks down lecithin to form a clear zone of precipitation around colonies.

Virchow cells

Foamy macrophages containing abundant acid-fast bacilli seen on histopathological examination of lesions in lepromatous leprosy.

Fernandez reaction

The early reaction in the Lepromin test read $24\text{--}48\text{ hours}$ after intradermal injection of lepromin antigen.

Mitsuda reaction

The late reaction in the Lepromin test read at $21\text{ days}$ after injection; an indurated nodule measuring greater than $5\text{ mm}$ indicates a positive reaction seen in tuberculoid leprosy.

Bacteriological index (BI)

A index measuring the density or quantity of acid-fast bacilli (AFB) per microscopic field in skin smears or tissue samples, scored on a scale of $0$ to $6+$.

Morphological index (MI)

The percentage of viable (solidly stained) acid-fast bacilli in skin smears, used to assess response to leprosy treatment.

McFadyean reaction

A staining technique using polychrome methylene blue (PCMB) for presumptive diagnosis of Bacillus anthracis, demonstrating pink/purplish capsular material (poly-D-glutamic acid) surrounding blue bacilli body.

Sulfur granules

Hard yellow/brownish clumps of filamentous bacterial colonies found in pus drained from sinus tracts, characteristic of Actinomycosis (Actinomyces israelii).

Koplik spots

Pathognomonic oral lesions presenting in the prodromal phase of Measles virus infection.

FAMA test

Fluorescent Antibody to Membrane Antigen test, considered the gold standard serological assay for assessing Varicella Zoster Virus (VZV) immunity.

Koilocytes

Epithelial cells displaying enlarged nuclei with perinuclear clearing, hyperchromasia, and irregular nuclear membranes; hallmark cytological features of Human Papillomavirus (HPV) infection on Pap smear.

HPV E6 protein

An early protein encoded by Human Papillomavirus that inhibits the p53 tumor suppressor gene, driving uncontrolled cellular proliferation.

HPV E7 protein

An early protein encoded by Human Papillomavirus that inhibits the Rb (retinoblastoma) tumor suppressor gene, reducing apoptosis.

Molluscum bodies

Large intracytoplasmic inclusion bodies within epidermal keratinocytes, diagnostic of Molluscum Contagiosum virus infection.

Spaghetti and meatballs appearance

The characteristic microscopic appearance of short hyphae and round yeast spores on KOH mount of skin scrapings from Tinea Versicolor caused by Malassezia species.

Sporothrix schenckii

A dimorphic fungus causing Sporotrichosis ('rose gardener's disease'); grows as a mycelial mold with rosette/daisy-head conidia at $25^\text{o}\text{C}$ and as cigar-shaped yeast cells at $37^\text{o}\text{C}$.

Rhinosporidium seeberi

An aquatic protozoan-like fungus that cannot be cultured in artificial media, causing Rhinosporidiosis characterized by large friable polypoidal mucosal growths containing mature sporangia filled with endospores.

Dracunculus medinensis

A parasitic nematode (Guinea worm) acquired by drinking water containing copepods with larvae, leading to subcutaneous migration and painful blister formation on lower limbs upon female worm emergence.

Eumycetoma

The fungal cause of Madura foot (e.g., Madurella, Exophiala, Acremonium) presenting with chronic subcutaneous swelling, sinus tracts, and discharge containing black or pale grains.

Actinomycetoma

The bacterial cause of Madura foot (e.g., Nocardia, Actinomadura, Streptomyces) presenting with chronic subcutaneous granulomatous lesions discharging yellow or white grains.

Coagulase test

A diagnostic laboratory test used to differentiate Staphylococcus aureus (coagulase positive) from coagulase-negative species like Staphylococcus epidermidis.

Id reaction

A secondary inflammatory skin hypersensitivity eruption (disseminated eczematous eruption) characterized by itching, erythema, and pustules occurring in response to a primary dermatologic infection.

Erythema migrans

The characteristic expanding red skin rash with central clearing associated with Lyme disease caused by Borrelia burgdorferi.

Cutaneous Larva Migrans (CLM)

An intensely itchy skin condition featuring serpiginous red epidermal tracks caused by the migration of non-human hookworm larvae (Ancylostoma braziliense or Ancylostoma caninum).

Trichinella spiralis

A parasitic roundworm acquired by consuming raw or undercooked meat containing encysted larvae, causing trichinosis with initial gastrointestinal distress followed by myalgia, fever, swelling, and marked eosinophilia.

Loa Loa

A filarial nematode (African eye worm) transmitted by Chrysops fly bites in West and Central Africa, causing loiasis with transient subcutaneous Calabar swellings and subconjunctival worm migration.

Cutaneous Leishmaniasis

A chronic parasitic skin infection caused by Leishmania species (L. tropica, L. major, L. mexicana) transmitted by female sandflies (Phlebotomus spp.), producing a non-healing ulcer (Oriental sore or Delhi boil) containing amastigotes (LD bodies).