Microbiology Flashcards
Genital ulcer disease causes
- syphilis
- genital herpes
- chancroid
- granuloma inguinale (donovanosis)
Syphillis
treponema pallidum
single, painless ulcer at inoculation site with heaped up border and clean base
dx with VDRL/RPR and darkfield microscopy
genital herpes
HSV
multiple painful superficial vesicles or ulcerations with erythematous base
dx with PCR, Tzanck smear (showing multinucleated giant cells)
chancroid
haemophilus ducreyi
deep purulent painful ulcers with matted/suppurative lymphadenitis
dx with gram stain & culture, PCR
cx shows GNR in a “school of fish” chain
granuloma inguinale (donovaginosis)
klebsiella granulomatis
painless, progressive, red serpiginous ulcerative lesions without LAD
dx with gram stain and culture (difficult), BIOPSY (look for Donovan bodies - clusters of blue or black staining, bipolar chromatin condensations in large mononuclear cells)
Hepatitis B Infection Phases (2)
Proliferative - entire virion and related Ag of episomal DNA present on cell surface (HBsAg, HBcAg) in conjunction with MHC I –> CD8+ TCs destroy infected hepatocytes –> elevated ALT and AST
Integrative - DNA incorporated into host genome in surviving hepatocytes –> antiviral Abs appear and stop viral replication
*cont to have inc risk of HCC bc of integration of DNA
Malaria organisms
Plasmodium:
- P. falciparum
- P. vivax (dormant liver form = hypnozoites)
- P. ovale (hyponozoites)
- P. malariae
Streptococcus pneumoniae most common cause of:
MOPS are OPtochin Sensitive
Meningitis
Otitis media (in children)
Pneumonia
Sinusitis
Lancet-shaped, gram-positive diplococci
Encapsulated, IgA protease
sx= rusty sputum, sepsis in sickle cell anemia and splenectomy
NO VIRULENCE W/O CAPSULE
JONES criteria
dx rheumatic fever c/b immune response to M protein of S. pyogenes
Joints - polyarthritis
Mneumonic for penicillinase resistant penicillins
used to tx MSSA
CONDM
Claxicillin Oxacillin Naficillin Dicloxacillin Methicillin
Anthrax exotoxin
Protective Antigen is needed for the other two to get into the cytosol.
Edema factor: inc cAMP by acting as adenylate cyclase causing edema and phagocyte destruction
Lethal factor: a zinc-dependent protease that inhibits MAPK signaling, causing apoptosis and multisystem physiologic disruption
Pertussis toxin
disinhibits adenylate cyclase through Gi ADP-ribosylation increasing cAMP –> edema and phagocyte dysfunction
Adenylate cyclase toxin
B. pertussis
functions as adenylate cyclase, inc cAMP, causes edema and phagocyte dysfunction
Botulinum toxin
blocks presynaptic release of ACh at NMJ –> flaccid paralysis
c. diff toxin A
recruits and activates neutrophils –> release of cytokines –> mucosal inflammation, fluid loss, diarrhea