Micro Flashcards
Transformation vs conjugation (homologous vs nonhomologous recombo) vs transduction vs transposition
Integrating foreign genetic material from environment into host genome of bacterial cell vs bacterial mating/sexual reproduction that involves conjugation bridge made of sex pili and it transfers Fertility (F) factor unidirectionally from donor male (F+) to recipient female (F-) (transfer b/w 2 closely related DNA sequences vs transfer b/w 2 not-alike DNA sequences) vs a virus/vector that transfers genetic material into bacterium aka bacteriophage infection vs transfer of DNA by a transposon; transfer plasmid-to-plasmid or plasmid-to-genome
outcomes of genetic transfer
- No change
- Loss of gene activity – if new DNA interrupts a chromosomal gene
- Enhanced gene function – if new DNA turns on a promoter or turns off a repressor
- New gene activity – if new DNA encodes a gene that was not previously in the bacterium and if new gene can be expressed in functional form
definitive host vs intermediate host vs reservoir vs vector
host in which a parasite = sexually mature –> sexual reproduction vs host required for completion of parasite life cycle, but parasite = sexually immature –> undergo asexual reproduction vs host that harbors an infection that can be transmitted to humans; generally have asymptomatic or minimal disease vs organisms (often arthropods) that transmit parasite; often are also intermediate hosts
how can parasites evade immune response?
change stages, change host, intracellular escape (hide from immune response), ag variation (change coat/shed it), molecular mimicry (look like host)
sxs of hookworm dz
Itching and rash at site of larval entry, anemia and protein deficiency
sxs of ascariasis. how is it transmitted?
intestinal blockage; if extraintestinal infxn –> pneumonitis, eosinophilic asthma-like response (basically trigger parasite immune response). ingest eggs
location of Onchocerca volvulus
Africa, Central and South America
sxs of Onchocerciasis or River Blindness
painless skin nodules, blindness; both from inflamm response to dying larvae
which nematode has Tissue tropism?
Toxocara canis; from intestines throughout body via blood, but most disease associated with liver or eye infection
3 dx of toxocara canis that all must meet
Clinical signs
Exposure to puppies or kittens or history of pica
Lab findings (including eosinophilia) and serology using serum or vitreous humor
Taenia solium: cysticercosis vs neurocysticercosis vs taeniasis
“bumps” under skin that may be tender vs variety of neurologic symptoms from headache to sz vs GI disease; tapeworm lodges in sm. intestine
Generally asymptomatic apart from detection of proglottids in feces (can be large enough to be detected by eye)
Diphyllobothrium latum can have migrating proglottids. What can happen?
cause intestinal obstruction and cholangitis
Hymenolepis nana (dwarf tapeworm)
found in young children w/ heavy infxn, can present w/ itchy anus or HA. dx: eggs in stool; misdx: E. vermicularis (pinworm)
Dipylidium caninum
from swallowing infected flea. asymptomatic. dx: detection of proglottids on perianal region, in stool, in diapers, on floor coverings or furniture; are mobile when passed, so often mistaken for fly larvae (maggots) or a grain of rice
Fasciolopsis buski –> Fasciolopsiasis
from human and swine reservoirs, from raw or undercooked aquatic plants bearing cysts. asymptomatic. dx: presence of adult flukes or eggs in feces or vomit
Fasciola hepatica –> Fascioliasis
snails = intermediate host, ruminants = more definitive host; from ingestion of raw freshwater plants. tissue tropism: liver & bile ducts. has 2 stages: 1) Acute phase – larval fluke migrates from intestines to liver –> inflamm, tissue destruction, toxic/allergic rxns, non-specific symptoms of abdominal pain, N/V, hepatomegaly, fever). Labs = elevated eos and transaminase levels; 2) Chronic phase – months to yrs after infection; inflammation and intermittent blockage of bile ducts or gallbladder (cholangitis, cholecystitis); pancreas = inflamed. dx: Eggs in stool or drainage/aspiration of duodenal or biliary tissue; Pseudofascioliasis – eggs in stool d/t recent ingestion of sheep or beef liver that contained eggs
Which trematode has immunoevasion by adults?
Schistosoma spp; secrete substances that resemble host proteins, coating themselves
Schistosomiasis/bilharziasis (4)
- Katayma’s fever – occurs with egg production. Rash and itchy skin 1-2 days after infection, then cough, fever, abd. pain, diarrhea 1-2 months later
- Tissue-specific manifestations as infection continues, have tissue fibrosis and granulomatous lesions around eggs
- Many symptoms are immune-mediated – fibrosis (reduced organ function), granulomas, immune-complex formation, hypersensitivity (to eggs)
- Hepatosplenomegaly and cirrhosis associated with chronic infection
how to dx schistosomiasis/bilharziasis?
eggs in stool or urine, serology by EIA possible using serum
giant roundworm vs pinworm vs hookworm vs tapeworm
Ascaris lumbricoides vs Enterobius vs Anklystoma duodenale, Necator americanus vs cestodes (carnival)
what does it mean for fungi to be systemic?
can spread to other organs
transmission, sxs, tx of histoplasmosis
bat/bird feces, environment to person; pulm dz but depends on intensity of exposure and immunologic status of host; tx depends on patients’ immune competence (Most resolve with supportive care and no antifungal)
how to dx coccidiodes?
Several serologic tests available (skin test common)
what does paracoccidiodes look like at 37 degrees C?
six or more blastoconidia connected to parent cell called “mariner’s” or “pilot-wheel”
how to distinguish aspergillus vs mucor?
acute angle hyphae vs right angle hyphae
sxs of Pneumocystosis/PCP
ground glass on CXR, exudate w/ plasma cells, hypoxia
which opportunistic and systemic fungus produce biofilms?
candida albicans
is candida spp endo or exogenous infxn?
mainly endo but can be exo from room contaminated equip or person to person
sxs of candida spp
Cutaneous infections occur in areas where skin surfaces occlude and are moist (i.e. armpits, groin, in between toes) and underneath toe/fingernails; Hematogenous candidiasis results in seeding of Candida into deeper tissues like the heart, eyes, bones/joints, and brain
how to dx vs tx candida spp?
Skin scraping and KOH, Culture to ID species level for later antifungal treatment choice, CHROMagar allows detection of mixed species of Candida vs Antifungal resistance and biofilm formation complicate treatment,
Remove nidus of infection to increase treatment success, Prevention is preferable to treatment (Avoid broad spectrum antimicrobials, meticulous catheter care, rigorous adherence to infection-control precautions, better hygiene practices)
why is candida auris rising?
- Often multidrug resistant (some resistant to all antifungal classes)
- Difficult to identify and can be misidentified leading to inappropriate management
- Causes healthcare outbreaks (Spreads easily between hospitalized patients and nursing home residents)
- 30-60% mortality in patients with C. auris (however, it is typically a secondary infection)
2 causative agents of cryptococcus?
C. gattii and C. neoformans
