Microbiology Exam 3

macroscopic fungi

• large, visible fungi that are primarily distinguished by their reproductive structures.

• mushrooms, rusts, smuts, puffballs, truffles, morels

microscopic fungi

small, often unicellular fungi that can only be seen under a microscope, including molds and yeasts

ergosterol

treats fungal disease

fungal growth and nutrition

• heterotrophic

• aerobic

• grows best at room temperature

• moist conditions

• slightly acidic pH (5-6)

• absorb smaller nutrients

fungal benefits in nature

• recycles nutrients

• mutualism with algae and plats

fungal benefits in industry

• antibiotics

• drugs

• food

• yeast for bread and fermentation

• chemicals

fungal organization (yeast)

• mostly round, some rods

• parent cells form blastospores by budding

• scar is left on the parent cell where spore released

vegetative mycelium

grows as a network of filamentous hyphae to digest and absorb nutrients

asexual sporulation

fruiting bodies form on the mycelium which produce spores

• asexual spores are genetic clones

types on asexual spores

• blastospores (Canidia)

• conidiospores (Aspergillus, Penicillium)

• sporangiospores (Rhizopus)

• arthrospores (Coccidioides)

sporulation

The process by which fungi produce spores, either sexually or asexually, to reproduce and disperse

dimorphism

The ability of some fungi to exist in two different forms, typically as yeast or mold, depending on environmental conditions

thermal dimorphism

subcutaneous

inoculated skin from trauma

systemic

invasive fungal infection affecting internal organs, typically respiratory (inhaled spores)

true infection

• well-developed degree of virulence

• restricted to endemic regions

• highly thermal dimorphic

opportunistic infections

infections that occur when the immune system is compromised, often caused by organisms that do not typically cause disease in healthy individuals.

anti fungal drugs

target cell membrane and wall

Dermatophytosis

• aka ringworm

• cutaneous mycoses

• pathogenic form: mold

• reservoir: skin, hair, nails, soil

• transmission: contact with hyphae or spores on contaminated material

• clinical features: cutaneous disease of epidermis, hair, and nails

• clinical subtypes: tinea pedis (athlete’s foot), tinea capitis (scalp hair), alopecia common (hair loss), tinea corporis (body), tinea cruris (groin or jock itch), tinea unguium (nail)

• risk group: irritated damp skin

• diagnosis: direct examination of skin

• treatment: topical or oral azoles

Sporotrichosis

• aka rose thorn disease

• pathogenic form: yeast

• subcutaneous mycoses

• etiological agent: Sporothrix schenckii

• reservoir: soil, plants (roses)

• transmission: direct inoculation through skin

• clinical features: chronic skin lesions and ulcerations

• diagnosis: culture of the organism from lesions

• treatment: oral potassium iodide.

Blastomycosis

• aka Gilchrist’s disease

• pathogenic form: thick walled yeast

• systemic mycosis from primary pathogen

• etiological agent: Blastomyces dermatitidis

• reservoir: soil, decaying organic matter

• transmission: inhalation of spores

• clinical features: pulmonary disease, skin lesions, systemic symptoms

• diagnosis: culture or serology

• treatment: Amphotericin B and azoles

• risk group: immunocompromised individuals

Coccdioidomycosis

• aka valley fever

• systemic mycosis from the primary pathogen

• pathogenic form: spherules with endospores

• etiological agent: Coccidioides immitis

• reservoir: soil in arid regions (SW America)

• transmission: inhalation of spores

• pathogenesis: enter lungs, convert to spherules containing endospores, swell and burst, high potential for spore dissemination

• clinical features: flu-like symptoms, pulmonary issues, and skin lesions

• diagnosis: serology or culture

• treatment: Amphotericin B and azoles

Histoplasmosis

• aka Ohio Valley Fever or Darling’s Disease

• pathogenic form: yeast in phagocytes

• systemic mycosis from primary pathogens

• etiological agent Histoplasma capsulatum

• reservoir: moist or dry dusty soil, Ohio/Mississippi river valleys

• transmission: inhalation of spores

• clinical features: flu-like symptoms, respiratory issues, disseminated disease in severe cases

• diagnosis: culture or serology

• treatment: Amphotericin B and azole

Aspergillosis

• etiologic agent: Aspergillus fumigatus

• pathogenic form: mold

• systemic mycoses from opportunistic pathogens

• Allergic Bronchopulmonary Aspergillosis (treated with steroids)

• Aspergilloma: golf ball-sized fungal ball in the lung cavities

• reservoir: decaying organic matter

• transmission: inhalation of spores

• clinical features: respiratory infections, allergic reactions, and systemic disease

• diagnosis: culture or serology

• treatment: voriconazole and other antifungals

Candidias

• etiologic agent: Candida albicans

• pathogenic form: yeast

• systemic mycosis from opportunistic pathogen

• reservoir: normal flora of humans

• transmission: opportunistic infection in immunocompromised individuals (vaginal canal to new born, STD)

• clinical features: oral thrush, yeast infections, and systemic infections

• attacks URT, GI, nails, and vagina

• diagnosis: culture or serology

• treatment: fluconazole and other antifungals

Cutaneous Candidiasis

• clinical manifestation: red rash, inflammation, pustules in damp skin areas

• common in intertriginous areas, such as skin folds and under breasts. It occurs when yeast overgrows due to moisture and friction.

Vulvovaginitis

• vaginal yeast disease

• clinical manifestation: yellow-white cheesy curd-like growth on vaginal wall, itching, pain, discharge

• sexually transmitted

Oral Candidiasis

• thrush

• clinical manifestation: white curd-like growth on the mucous membrane of the mouth

• risk group: newborns and elderly

• common in immunocompromised individuals, can spread from the vagina.

Cryptococcosis

• etiologic agent: Cryptococcus neoformans

• pathogenic form: encapsulated yeast

• systemic mycosis from opportunistic pathogens

• reservoir: associated with birds, soils that are nitrogen-enriched from droppings, urban areas

• transmission: inhalation of airborne yeast cells into the alveoli

• clinical manifestation: meningitis, mild pulmonary diseases

• diagnosis: lumbar puncture

Pneumocystis

• etiologic agent: Pneumocystis jiroveci

• pathogenic form: cystic yeast

• systemic mycosis from opportunistic pathogen

• reservoir: wildspread

• transmission: respiratory droplets or organisms inhaled into the lungs

• clinical features: forms yeast/cysts in lung tissue, immunocompromised people develop Pneumocystis Carinii Pneumonia (PCP), likely in AIDS patients

• treatement: Pentamidine, Thrimethoprim-sulfamethoxazole

Aflatoxicosis

A disease caused by exposure to aflatoxins, toxic compounds produced by certain molds, primarily affecting the liver and associated with dietary contamination.

encystment

The process by which certain microorganisms form a protective cyst around themselves to survive unfavorable environmental conditions.

excystment

The process where a dormant cyst reverts to its active, vegetative form, typically after exposure to favorable environmental conditions.

trophozoite

The active, motile feeding stage of certain protozoa, characterized by its ability to obtain nutrients and reproduce.

Amoebiasis

• etiologic agent: Entamoeba histolytica

• 2nd leading cause of death from parasitic disease in the world

• reservoir: humans, food, water

• transmission: fecal-oral

• attacks GI

• treatment: Metronidazole

Primary Amoebic Meningoencephalitis (PAM)

• etiologic agent: Naegleria fowleri

• reservoir: warm fresh water with high bacteria counts

• transmission: accidental parasite, lots of exposure, swimming, sinus rinses

• path: migrate from mucosa to brain via olfactory nerve

• attacks the brain

• diagnosis: analyze CSF

• treatment: 95% fatal

Giardiasis

• etiologic agent: Giardia lamblia

• reservoir: humans, animals

• transmission: fecal-oral

• path: ingest cyst, trophozoite coats SI, interferes with fat absorption, foul-smelling stool, trophozoites or cysts in feces

• attacks GI

• diagnosis: stool tests

• treatment: Metronidazole or Tinidazole

Trichomoniasis

• etiologic agent: Trichomonas vaginalis

• reservoir: humans (incubation of 5-28 days)

• transmission: sexual contact

• clinical manifestation: often asymptomatic but can cause vaginal discharge, itching, and discomfort

• diagnosis: microscopic examination of discharge

• treatment: Metronidazole

Toxoplasmosis

• etiologic agent: Toxoplasma gondii

• reservoir: cat feces, undercooked meat

• transmission: ingestion of oocysts or cysts

• attacks CNS, lymph nodes, and can cross the placenta attacking the fetus

• diagnosis: serological tests or imaging

• treatment: pyrimethamine and sulfadiazine

Pinworm disease

• most prevalent helminth

• etiologic agent: Enterobius vermicularis

• life cycle: egg ingested, larvae in SI and migrate to LI, female migrates to the perianal area at night and lay eggs, eggs passed hand to mouth

• treatment: mebendazole

Whipworm disease

• etiologic agent: Trichuris trichiura

• life cycle: eggs ingested, larvae emerge and attach to SI, adults migrate to LI and attach, mature adults produce 100s of eggs per day for a year, feces in soil

• treatment: mebendazole

Ascariasis

• etiologic agent: Ascaris lumbricoides

• life cycle: eggs ingested, larvae emerge in LI, larvae penetrate intestinal wall, enter circulatory/lymphatic system and migrate to lung, larvae coughed up from lung, swallowed and reach intestines for 2nd time, mature to adults in SI, mate and produce eggs, feces in soil

• attacks GI and LRT

• treatment: mebendazole

Hookworm

• etiologic agent: Necator americanus

• life cycle: eggs enter soil from human feces, Rhabditiform larvae emerge, revert to filariform larvae, larvae in soil enter through skin, larvae enter blood/lymphatic, enter lungs, coughed up and swallowed, larvae migrate to SI, intestinal hemorrhage leads to bloody diarrhea

• attacks GI, muscle, and CNS

• treatment: mebendazole

Trichinosis

• etiologic agent: Trichinella spiralis

• life cycle: cysts shed in fecal waste, cysts in soil ingested by pigs, larvae emerge in animal intestine, larvae migrate to muscle and cysts form, humans consume undercooked pork with cysts

Tapeworm

• etiologic agent: Taenia saginata (beef) or Taenia solium (pork)

• life cycle: eggs or proglottids passed in feces, contaminated food or water ingested, larvae develop in intestine, attach to intestinal wall, mature into adults, produce proglottids that are expelled in feces.

• treatment: praziquantel

properties of viruses

• lack of structure

• genome contains DNA or RNA

• no independent metabolic reactions

• replicate only within host cells

virus envelope

aids in attachment and penetration of host cell membrane

virus spikes

are glycoprotein structures on the surface of viruses that facilitate attachment to host cells, playing a crucial role in the infection processand are essential for viral entry into host cells.

virus capsid

is the protein shell of a virus that encases and protects its genetic material, providing structural support and aiding in the delivery of the viral genome into host cells

virus nucleocapsid

is a complex of the viral capsid and the nucleic acid it protects, serving as a critical component for virus assembly and infection

virus life cycle (replication)

1. spikes, capsids, or envelope attach to host cell surface

2. penetration of virus into host cell

3. uncoating of viral nucleic acid

4. replication, synthesis, and assembly of viral structures

5. release of virions from host cell

positive RNA viruses

• are a group of viruses that have positive-sense single-stranded RNA genomes, which can be directly translated into proteins by the host cell's ribosomes

• These viruses typically replicate within the cytoplasm and can include notable examples such as poliovirus and coronaviruses.

negative RNA viruses

• are a group of viruses that contain negative-sense single-stranded RNA genomes, which must be converted into positive-sense RNA by an RNA polymerase before they can be translated into proteins

• These viruses often replicate in the cytoplasm and include examples like influenza and Ebola viruses.

retroviruses

are a group of RNA viruses that reverse transcribe their RNA genome into DNA after entering a host cell. This DNA is then integrated into the host's genome, allowing the virus to replicate with the host's cellular machinery.

Cytopathic Effect (CPE)

• host cell changes due to viral infection

• visible cell abnormalities

interferon

precents viral replication in cells by inducing the expression of antiviral proteins and enhancing the immune response.

viral replication in DNA viruses

is the process by which DNA viruses use the host's cellular machinery to produce new viral genomes and proteins after entering the host cell.

viral replication in positive and negative RNA viruses

is the process by which RNA viruses utilize the host's ribosomes to translate their RNA into proteins and replicate their genomes, differing in how they use their RNA as a template for mRNA production.

viral replication in retroviruses

is the process by which retroviruses convert their RNA genome into DNA using reverse transcriptase upon entering the host cell, integrating into the host genome to produce new viral particles.

viroid

• causes disease in plants

• has naked nucleic acid

prion

• infectious abnormal protein

• disease in animals (mad cow disease)

cysticerci

the encysted larval forms of certain Taenia species, which typically infest muscles of mammalian intermediate hosts