MICROBIAL DISEASES PART 1

Vocabulary flashcards covering key microbes, diseases, diagnostic features, treatments, and epidemiology from the lecture notes.

Candida albicans

The most common Candida species; a yeast that reproduces by budding and forms pseudohyphae; part of normal human flora and an opportunistic pathogen; causes thrush and invasive infections; treated with antifungals such as fluconazole.

Candida auris

Multi-drug resistant Candida species; nosocomial outbreaks; persists on surfaces and is difficult to eradicate; associated with high mortality in invasive infections.

Cryptococcus neoformans

Encapsulated yeast; opportunistic pathogen that often causes meningitis in immunocompromised individuals.

Cryptococcus gattii

Encapsulated yeast related to C. neoformans; can cause infection in both immunocompromised and immunocompetent hosts depending on region.

Malassezia furfur

Lipophilic yeast that overgrows in sebaceous areas; causes tinea versicolor (pityriasis versicolor) with hypopigmented or hyperpigmented patches; diagnosed with Wood lamp and KOH prep; treated with selenium sulfide and antifungals.

Pneumocystis jirovecii

Yeast-like fungus causing Pneumocystis pneumonia, especially in immunocompromised individuals.

Mucorales (Mucor and Rhizopus)

Mucormycetes; molds with non-septate hyphae that invade vessels; cause mucormycosis; high risk in diabetics (DKA) and immunosuppressed; treatment includes early surgical debridement and amphotericin B; may use isavuconazole.

Aspergillus fumigatus

Mold with septate hyphae and acute-angle branching; inhaled spores; causes invasive aspergillosis in immunocompromised hosts; first-line treatment typically voriconazole.

Dermatophytes

Keratinophilic molds that infect keratinized tissues (skin, hair, nails); genera include Microsporum, Trichophyton, Epidermophyton; transmitted by direct contact or contaminated fomites; cause tinea infections.

Microsporum

Dermatophyte genus; primarily infects skin and hair; often zoonotic; causes various dermatophytoses with ectothrix hair invasion.

Trichophyton

Dermatophyte genus; infects skin, hair, and nails; common in chronic infections; some species are zoonotic.

Epidermophyton

Dermatophyte genus; infects skin and nails; does not infect hair; associated with jock itch and athlete’s foot; transmitted person-to-person or via contaminated surfaces.

Tinea versicolor (Pityriasis versicolor)

Overgrowth of Malassezia furfur causing hypopigmented or hyperpigmented patches on skin; diagnosed with Wood lamp and KOH; described as “spaghetti and meatballs” on microscopy; treated with selenium sulfide and antifungals.

Leishmania spp.

Flagellated protozoan transmitted by sandflies; causes cutaneous leishmaniasis (skin ulcers) and can cause mucosal/visceral disease depending on species; amastigotes found inside macrophages; diagnosed by visualization of amastigotes; treated with agents such as liposomal amphotericin B for mucosal disease.

Acanthamoeba spp.

Amoeboid protozoa; cause keratitis (eye infections) among contact lens wearers; life cycle includes cysts and trophozoites; diagnosed by visualization in corneal scrapings; treated with antiseptics like polyhexamethylene biguanide or chlorhexidine.

Trichinella spiralis

Nematode (pork roundworm); acquired by eating undercooked/raw pork or game meat; larvae encyst in striated muscle; symptoms include myalgia, periorbital edema, fever; diagnosed by serology or muscle biopsy; treated with albendazole or mebendazole; prevention includes proper cooking/freezing and safe meat handling.

Blastomyces dermatitidis

Dimorphic fungus; mold in the environment, yeast in humans; broad-based budding yeast; causes blastomycosis (pulmonary with possible dissemination to skin, bone, and CNS); treated with itraconazole for mild/moderate disease and amphotericin B for severe disseminated disease.

Coccidioides

Dimorphic fungus causing coccidioidomycosis (Valley Fever); inhalation of arthroconidia from soil; endemic to parts of the Americas; treatment varies by severity (including azoles or amphotericin B in severe cases).

Histoplasma

Dimorphic fungus; inhalation of microconidia; disease ranges from asymptomatic to pulmonary disease; endemic in certain regions; treated with itraconazole or amphotericin B for severe disease.

Paracoccidioides

Dimorphic fungus endemic to parts of South America; described by characteristic “pilot wheel” budding yeast; causes paracoccidioidomycosis; treated with itraconazole.

Sporothrix schenckii

Dimorphic fungus; “rose-handler’s disease”; infects via traumatic inoculation of conidia into skin; lymphocutaneous spread along lymphatics; diagnosed by culture and characteristic yeast/colonial forms; treated with itraconazole (3–6 months) or terbinafine.

Tinea capitis

Dermatophyte infection of the scalp; common in children; may cause hair loss and scaling.

Tinea corporis

Dermatophyte infection of the body; ring-shaped rash with scaling.

Tinea cruris

Dermatophyte infection of the groin (jock itch); usually in warm, humid conditions.

Tinea pedis

Dermatophyte infection of the feet (athlete’s foot); often between toes with scaling and itching.

Tinea unguium (onychomycosis)

Dermatophyte infection of the nails; leads to nail thickening and discoloration.

Tinea barbae

Dermatophyte infection of the beard area; usually seen in men with facial hair exposure.

KOH prep

Potassium hydroxide prep used to clear human cells and reveal fungal elements (branched, septate hyphae and sometimes macroconidia) under microscopy.

Wood lamp

Ultraviolet light used in dermatology; can help diagnose tinea capitis when fluorescence is observed (not always positive).

Spaghetti and meatballs

Microscopic appearance (yeast and short pseudohyphae) typical of Malassezia furfur in tinea versicolor.

Voriconazole

Azole antifungal; first-line therapy for invasive aspergillosis; not effective against Mucorales.

Liposomal Amphotericin B

Amphotericin B formulated in liposomes to reduce nephrotoxicity; used for mucormycosis and other severe systemic fungal infections.

Itraconazole

Azole antifungal; used for blastomycosis, histoplasmosis, sporotrichosis, and some other systemic mycoses; often a step-down therapy after initial treatment.

Terbinafine

Allylamine antifungal; effective for dermatophyte infections; often used orally for stubborn cases and terbinafine cream for skin.

Selenium sulfide (Selsun)

Topical antifungal/antifungal shampoo used to treat tinea versicolor (Malassezia overgrowth) and other superficial fungal infections.

Epidemiologic levels of disease: Sporadic

Occurs infrequently and irregularly; not consistently present in a population.

Endemic

Constant presence and/or usual prevalence of a disease in a geographic area.

Epidemic

Increase in the number of cases above what is normally expected in a population in a given area.

Outbreak

Epidemic confined to a more limited geographic area or a brief period.

Pandemic

Epidemic that has spread across multiple countries or continents, affecting a large population.

Common-source outbreak

An outbreak where a group of persons is exposed to the same source of infection or toxin.

Point-source outbreak

A type of common-source outbreak with a single brief exposure leading to cases peaking early.

Contiguous outbreak

Outbreak where exposure occurs over an extended period (days–weeks) from a source.

Propagated outbreak

Outbreak transmitted from person to person; results in successive waves of cases.

Vector-borne outbreak

Outbreak transmitted by a vector (e.g., sandflies in Leishmaniasis), often requiring vector control.