Microbio 4 2
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- what is the MOA for bacitracin?
- disrupts cell membranes
- all the bacteria discussed in the food & water borne infections lecture (basically) share what same characteristic?
- they're all gram(-)
- what is the main EHEC virulence factor to remember?
-
SLT -- shiga-like-toxin
stops protein synth; destroys intestinal epithelium --> blood slough - how big of an inoculum is required for salmonella infection?
- large dose
- what are the two virulence factors for salmonella?
-
(1) enterotoxin -- cholera-like
(2) cytotoxin -- inhib protein synth - when are the symptoms of Salmonella enterica Typhi seen?
- 1-3 weeks after ingestion
- what is a major point to remember about salmonella (typhoid) invasion system
- type III --> ruffling --> "phagocytosis"
- how does Shigella enter M cells of intestine?
- "invasion plasmid antigens" (IpaBCD) to enter M cells, and pass through into lamina propria
- what virulence factor does shigella need to spread from cell to cell?
- IcsA -- Intracellular spread ATPase (actin polymerization)
- how many organisms needed to ingest to become infected with V. cholera?
- lots
- what are the three genera of spirochetes
- treponema, borrelia, and leptospira
- what is the causative agent of syphilis?
- T. pallidum
- desc the three stages of syphilis
-
(1) primary stage
sex transmission; chacres develop w/in 2-4 wks exposure; highly infectious
(2) secondary stage
3-6 wks after primary; flu-like illness, fever, sore throat, headache, hair loss, etc; very infectious soars
(3) tertiary stage
may be LONG after secondary; organ and tissue distruction via gumma (granulamatous lesions of soft tissue and viscera) - what is the drug of choice for treatment of syphilis?
- penicillin
- what are bejel, yaws and pinta and where do they occur?
-
nonsexual versions of syphilis
bejel -- eastern meditteranean and w africa
yaws -- equatorial
pinta -- indians of mexico - yaws full name
- T. pallidum subspecies pertenue
- pinta full name
- T. pallidum subspecies carateum
- bejel full name
- T. pallidum subspecies endemicum
- which treponemal species is most strongly associated with periodontal disease?
- T. denticola
- vincents angina
- an oral infection of the mouth and gums; a polymicrobial infection involving fusobacterium necrophorum and treponema vincentii
- gram stain and morphology of neisseria species
- small gram(-) arranged in pairs (diplococci) with flattened adjacent sides (resembling kidney beans)
- motility and metabolism of neisseria
-
non-motile (no flagella)
aerobic metabolism -- oxidase positive - N. meningitidis produces acid from which of the following: glucose, maltose, lactose, sucrose
- glucose, maltose
- what determines N. meningitidis serogroup?
- the capsular polysaccharide
- what determines N. meningitidis immunotype?
- Lipooligosaccharide (LOS)
- reduces severity of neurological sequelae of N. meningiditis
- dexamthazone (use is controversial)
- chemoprophylaxis for N. meningiditis
- oral rifampin (or ciprofloxacin)
-
N. gonorrhoeae
- produces acid from what?
- oxidase? - oxidase positive and produces acid from glucose only
- phase variation of N. gonorrhoeae
- shift b/t P+ (piliated) P++ (highly piliated) and P- (non-piliated), mediated by chromosomal recombination
- does N. gonorrhoeae exhibit capsular polysaccharides?
- NO
-
how do you distinguish the following organisms from Neisseria gonorrhea?
Acinetobacter
Kingella
Moraxella -
Acinetobacter: oxidase negative
Kingella: oxidase positive coccoid bacilli, catalase negative
Moraxella: does not produce acid upon fermentation of glucose - therapy for uncomplicated urethral, cervical, or rectal N. gonorrhoeae infection
- ceftriaxone
- what should you add to the treatment regimen for N. gonorrhoeae is patient if coinfected with Chlamydia trachomatis
-
ceftriaxone (for N. gonorrheoeae)
doxycycline or azithromycin added - desc the peptidoglycan layer of Chlamydia
- they don't have one
- transmission in C. psittaci
- humans infected only by inhaling organisms in dried bird feces
- what is the most common STD in the US
- chlamydia trachomatis
- what are the two forms of borrelial relapsing fever?
-
tick borne (TBRF)
louse borne (LBRF) - what is the treatment for borrelial relapsing fever?
- doxycycline, erythromycin
- reservoir for lyme disease
-
deer, mice, small mammals, lizards
ticks are not reservoirs, but they are the primary TRANSMITTERS - treatment for lyme disease
-
doxycycline in early phases
IV rocephin in later stages - where is the flagella of spirochetes located?
- periplasmic endoflagella, in between the outer and inner membranes
- what type of microscopy do you use to visualize spirochetes?
- darkfield microscopy (cause they're thin)
- what are the two ways to confirm a diagnosis of syphilis, and what stages are they useful for
-
non-treponemal (VDRL & RPR)
- secondary and latency
- best in neurosyphilis
treponemal (FTA & MHA)
- best for early and late stage -
treatment of choice for syphilis
- how 'bout for neurosyphilis
- how 'bout for HIV patients? -
penicillin
neurosyphilis --> chloramphenicol
HIV patients --> ceftriaxone - what is the only pathogenic gram(-) cocci?
- neisseria
- does N. gonorrheae have a polysaccharide capsule?
- NO
- N. meningitidis PorB
-
- translates into host cell membranes
- effects on apoptosis
- induces phagocytosis - which serogroup is the most common cause of epidemic meningitis?
- Serogroup A
- Waterhouse-Friderichsen Syndrome
-
systemic meningitidis infection
- adrenal glands destroyed - gonococcal opacity protein
-
(Opa) -- PII
- allows cell-to-cell adherence
- influences cell tropism - of the gonococcal porins, which one leads to disseminated and which one to localized infection?
-
PorB1A disseminated
PorB1B localized - what bug is the cause of opthalmia neonatorum?
- N. gonorrhoaea
- therapy for N. gonorrhoeae infection
- ceftriaxone, ciprofloxacin
- therapy for N. gonorrh coinfection with Chlamydia trachomatis?
- ceftriaxone + doxycycline
- desc the vaccine for N. gonorrhoeae
- no vaccine available
- differentiate b/t presumptive and definitive diagnosis of gonorrhoeae
- The "presumptive diagnosis" only requires that 2 out of the 3 conditions be met. Thus, the presence of GNIDS in a urethral exudate and detection by an antigen detection test, in the absence of growth and isolation of N. gonorrhoeae, would be sufficient for a presumptive diagnosis. However, a "definitive diagnosis" requires both cultivation of N. gonorrhoeae from sites of exposure AND confirmation with biochemical tests.
- what is special about the borrelia genome?
- segmented genome -- linear and circular DNA
- clinical picture of relapsing fever
-
- borrelia
- massive numbers of spirochetes in blood - what accounts for the "relapse" of relapsing fever
-
Vmp antigenic variation protein
- about 40 of em
- 1 expressed at a time
- immune syst kills bacteria --> some recombination --> relapse --> continue cycle - treatment for relapsing fever
- doxycycline, erythromycin
- is there any transovarial transmission for lyme disease?
- NO
- what is the specific ELISA test for lyme disease?
- C6 peptide ELISA test
-
yersina pestis
- general info - gram(-) rods, facultative anaerobes, enterobacteriaceae family, nonmotile
- symptoms of bubonic plague
- swollen ulcerated lymph node (bubo); surface hemorrhages may cause the skin to turn black (black death)
- treatment for bubonic plague
- antibiotics (streptomycin, chloramphenicol, or tetracycline)
- pathogenesis of bubonic plague
- flea bite --> blood stream --> PMNs (killed), nonactive macs (live) --> carried to mesenteric lymph node --> buboes --> leave mac and go through bloodstream --> subcutaneous hemorrhages
- what are the three virulence factors for yersina?
-
(1) adhesins
(2) plasmid-encoded YOP proteins -- injected into host cells by Type III secretion
(3) Plasminogen Activator Protease -- prevents clots - Francisella Tularensis "tularemia" general info
- small gram(-) rods, facultative anaerobe, require a rich medium + cystine
- what is the most virulent organism to infect humans?
- Francisella Tularensis
- what are the three major manifestations of tularemia?
-
(1) ulceroglandular tularemia
(2) pneumonic tularemia
(3) typhoidal tularemia - which disease is associated closely with rabbit hunters?
- tularemia (Francisella Tularensis)
- why is francisella tularensis such a good potential biowarfare agent?
-
(1) EXTREME infectivitiy
(2) ease of dissemination
(3) substantial capacity to cause illness and death - Human Brucellosis -- aka
- Malta fever
- Human Brucellosis
- reticuloendothelial system (RES) primarily infected producing prolonged febrile systemic illness
- infected cat or dog bite -- what organism?
- Pasteurella Multocida
-
Pasteurella Multocida
- general desc - small gram(-) coccobacilli
- what are the two smallest known free living bacteria?
- mycoplasma and ureaplasma
- what class do mycoplasma and ureaplasma belong to?
- mollicutes
- desc the unique structure of mollicutes
- lack a cell wall or peptidoglycan and contain sterols in their membrane
- what is referred to as walking pneumonia?
- pneumonia caused by mycoplasma pneumoniae (for people aged 5-35)
- what are the preferred antibiotics for mycoplasmal pneumonia and why?
-
erythromycin and doxycycline
Remember, cell wall inhibitors are ineffective - mycoplasma hominis
- causes urethritis in males; sexual transmission
- ureaplasma urealyticum
- same diseases as Mycoplasma but may also be involved in urinary tract stones
- what is the etiological agent of granuloma inguinale?
- calymmatobacterium granulomatis
-
Rickettsia
- general info -
enter cells by induced phagocytosis
produce membrane disrupting phospholipase A (escape from phagolysosome fusion)
can obtain ATP from host mitochondria - what is the hallmark of rickettsial infections?
- necrotizing vasculitis and INC vascular permeability
- what are the three major groups of rickettsia?
-
(1) rocky mountain spotted fever (RMSF) group
(2) typhus group
(3) scrub typus group -
rocky mountain spotted fever
- transmitted by? - dermacentor ticks (dog or wood ticks) --> also maintained in ticks by transovarial transmission
- clinical picture of rocky mountain spotted fever
- fever, chills, headache and myalgia, 3-5 days later rash spreads
-
rickettsia prowazekii
- causative agent of? - epidemic or louse borne typhus
- Brill-Zinsser disease
- epidemic typhus reactivating decades after initial infection
-
coxiella burnetti
- associated with what condition? - Q fever
- Q fever
- primarily an occupational disease associated with working with cattle, sheep, or goats
-
coxiella burnetti
- grows where in cell? - exclusively in phagolysosomal vesicle of cell
- two variants of coxiella burnetti
-
(1) small cell variant (SCV) -- environmentally stable form
(2) large cell variant (LCV) -- metabolically active form - pathology of coxiella burnetti
- respiratory (pneumonia) with high fever, which can last a LONG TIME; hepatomagaly and splenomegaly are common
- HME
-
Human monocytic ehrilichiosis
HME is a tick borne infection caused by Ehrlichia chaffeensis -
Sennetsu fever
- caused by - Ehrlichia sennetsu
-
HGE
- stands for
- causative agent
- tranmission by -
Human granulocytic anaplasmosis
Anaplasma phagocytophilum
tick bite -
Staphylococcaceae
- gram stain - gram(+)
-
Staphylococcaceae
- sugar fermentation - ferments glucose
- what is the major test used to distinguish between virulent and avirulent species of Staphylococcaceae?
- Coagulase test is the major test used to distinguish virulent (S. aureus; coagulase(+)) from avirulent (S. epidermidis, S. saprophyticus).
- the characteristic lesion caused by staph is . . .
- abscess
- what is the major virulence factor of S. epidermidis?
-
biofilm formation
cause: Polysaccharide Intercellular Adhesin (PIA) - Protein A
-
e.g. Staphylococci
binds to Fc fragment of IgG subclasses preventing opsonization -
MSCRAMMs
- which species of Staph has it? - S. aureus
- toxic shock syndrome toxin is a what?
- superantigen
- enterotoxin is a what?
- superantigen
-
Staphylococci
- what does toxin exfoliatin do? - cleaves desmosomes that hold the most superficial layer of skin together; results in blistering and loss of superficial skin layer
- what is the most common cause of food poisoning?
- S. aureus enterotoxin
- what is the most common cause of pyogenic skin infections?
- S. aureus
- what is the major class of antibiotics used to treat staphylococcal infections?
- B-lactams
- what is the DOC for treating methicillin-resistant staphylococci?
- vancomycin
- from where do the staphylococci get resistance to antibiotics?
- acquire individual genes, usually on plasmids
- what organism is second to E. coli in causing UTIs in young sexually active women?
- S. saprophyticus