Micro Exam 3 2
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- most common cause of ascending UTI
- E. Coli
- enterobacteria associated w/ urinary stones
- proteus mirabelis (produces potent urease to produce ammonia and make urine alkaline)
- gram + causes of UTI
- staph saprophyticus, staph epidermis, and enterococcus
- causes UTI in young sexually active women
- staph saprophyticus
- causes UTI in hospitalized pts
- Staph. epidermis and Enterococcus
- viral UTI common?
- no
- viral UTI causes?
- human polyomavirus, adenovirus, hantavirus
- How does humanpolyoma infect?
- enters via respiratory tract and spreads to tubular epithel cells in kidneys and ureters. establishes latency
- 35% of healthy individs have infx with ____________ but it remains latent
- polyomavirus
- fungal causes of UTI
- candida and histoplasma capsulatum
- parasitic causes of UTI
- Trichomonas vaginalis, Schistosoma haematobium
- which causes urethitis in males/vaginitis in females
- T. vaginalis
- which causes allergic response to worm’s egg leading to scarring in area where bladder/ureters meet and ureters get blocked- results in bladder inflammation
- S. haematobium
- mechanical factors that predispose to UTI
-
1. shorter female urethra
2. sexual intercourse
3. uncircumcised boys - obstructions to complete bladder emptying
-
1.residual urine
2. loss of neurologic control
3. vesicoureteral reflux
4. diabetes mellitus
5. catheterization - causes of loss of neurological control:
- spina bifida, paraplegia, multiple sclerosis
- who is vesicoureteral reflux common with
- children w/ anatomic abnormalities of the urinary tract
- diabetes mellitus may lead to...
- pyelonephritis
- where do most urinary tract pathogens originate
- fecal flora
- which can colonize/infect the urinary tract
- aerobic and facultative species such as E. coli
- what structural feature helps E. coli adhere to epithelium
- fimbriae
- what does E. coli produce that causes kidney damage
- hemolysin
- is healthy urinary tract resistant to bacterial colonization?
- yes- eliminates microorganisms rapidly/efficiently
- how
- via pH, chemical content, and flushing mechanism
- 3 clinical features of acute lower UTIs (bladder infxs)
- dysuria, urgency, frequency
- urine sample shows:
- cloudiness due to pyuria and bacteriuria, hematuria
- what may result from an ascending infx?
- acute bacterial prostatis
- sx?
- asymptomatic
- upper UTI spreads to
- kids
- what is pyelonephritis
- kidney infx
- sn/sx
- ranges from moderate diarrhea to severe lasting 20 days in immunocompromised
- common cause of upper UTIs
- staphylococci
- what can repeated episodes lead to
- loss of fx of renal tissue, and HTN
- how is infx distinguished
- quantitative culture methods
- definition of bacteriuria
- over 10^5 organisms/mL
- T/F usually are several bacterial species
- F- only one
- do a significant proportion of lower UTI pt's have recurrent infxs?
- yes- either by same organism or by different one
- does upper or lower cause renal abcesses
- upper
- methods of urine collection
-
1. sterile container by pt
2. "bag urine" for babies/infants
3. catheter- collected from tube with syringe and needle - Tx of UTI
- antibiotics- ie augmentin
- prevention of UTI
- empty bladder often (esp after intercourse), prophylactic anti-biotic use, good catheter care
- host factors that influence risk of acquiring an STD
- genital lesions or ulcers, uncircumcised men, multiple infx
- What causes syphilis
- the spirochete Treponema pallidum
- how does it enter body
- minute abrasions on skin or mucous m'branes
- why does transmission require close contact
- b/c doesn't survive well out side body, sensitive to drying, heating, disinfectants
- spread?
- poor sanitation and personal hygiene
- 5 stages of syphilis pathogenesis?
- 1. initial contact 2. primary syphilis 3. secondary 4. latent 5. tertiary
- what occurs w/ initial contact
- 2-10 wks: treponemes multiply at infx site, develop a primary painless chancre
- primary?
- 1-3 months; treponemes proliferate, enlarged inguinal nodes and spontaneous healing
- secondary?
- 2-6 weeks: treponeme multiplication,flu-like illness, headache, fever, mucocutaneous rash and spontaneous healing, lesions in lymph nodes, liver, joints, muscles, skin and mucous m'branes
- latent
- 3-30 years: treponemes are dormant in liver or spleen, no sign of illness
- tertiary
- re-awakening, multiplication, dissemination, and invasion of trepes; neurosyphilis (general paralysis), and cardiosyphilis (aortic lesions, heart failure; progressive and destructive
- does T. pallidum respond to vigorous immune response
- no
- how does it evade recognition and elimination by the host
- maintains a cell surface rich in lipid that is antigenically unreactive
- when is congenital syphilis acquired
- first 3 mos of pregnancy
- results in:
-
1. serious infx--> intrauterine death
2. congenital abnormalities
3. silent infx (at 2 y.o) - tx
- antibacterial agents not helpful; polyvalent antitoxin recommmended
- prevention
- condoms
- what causes gonorrhea
- gram pos diplococcus Neisseria gonorrheae
- resevoir:
- humans
- transmission:
- eating sewage contaminated shellfish or mussels
- does it survive outside the body?
- no- sensitive to drying
- men or women more?
- women
- 4 special mechanisms of N. gonorrhea to allow mucosal attachment:
-
1. fimbriae (attachment and antigenic diversity
2. LPS (endotoxin activity)
3. IgA protease (destroys IgA1)
4. capsule (resists phagocytosis) - how do they infect?
- invade non-ciliated epithelial cells that internalize the bacteria, allowing them to multiply in intracellular vacuoles protected from phagos and Abs
- how does it damage host
- by inflammatory response elicited by organism
- sn/sx in males
-
discharge/pain
-complications rare - sn/sx in females
- discharge- no pain, assymptomatic therefore don't seek treatment
- female complications of gonor:
- PID, chronic pelvic pain, infertility
- ophthalmia neonatorum:
- gon in infants, characterized by sticky discharge
- other parts infected by gon:
- throat, rectum (purulent discharge)
- Cause of chlamydial infxs:
- Chlamydia trachomatis serotypes D-K
- 2 forms:
-
elementary body (EB):extracellular survival
reticulate body (RB): intracellular multiplication - how does it invade/infect?
-
-enter host thru small mucosal abrasions
-bind specific receptors on host and enter by endocytosis
-lysosome fusion is inhibited and EB begins development
-after 9-10 hrs become active RBs
-new EBs produced - pathogenesis in men:
- urethritis, epidymitis, proctitis, conjunctivitis
- pathogenesis in women:
- urethritis, cervicitis, salpingitis, conjunctivitis
- causes of inguinal lymphadenopathy:
- genital infxs, LGV, chancroid, donovanosis
- cause of LGV:
- C. trachomatis serotypes L1, L2, and L3
- pathogenesis of LGV:
-
-after 1-4 wks primary lesion develops at site of inoculation
-fever/headache accompany
-lesion heals rapidly and draining lymph nodes are infected causing inguinal buboes - complications
- proctitis, fever, hepatitis, pneumonitis, meningo-encephalitis
- tx:
- spiramycin (immunocompromised only)
- cause of chancroid (soft chancre):
- H. ducreyi
- characteristics:
-
-assymptomatic infxs (mild)
-self-limiting diarrhea 7-10 days
-immunocompromised may develop chronic infx - cause of donovanosis:
- Calymmatobacterium granulomatis
- which is most common form of genital ulcers in africa and asia
- chancroid
- which is common in caribbean, new guinea, india, and central australia
- donovanosis
- What causes mycoplasmas and non-gonococcal urethritis?
- mycoplasma hominis and ureaplasma urealyticum
- where do they colonize?
- genital tracts of healthy sexually active people
- what are they also associated with
- PID, postabortal and postpartum fevers
- what are other causes of vaginitis and urethritis
- candida albicans, trichomonas vaginalis, gardnerella vaginalis
- characteristics of candida
-
-irritant vaginitis
-cheesy discharge
-UTI with it maybe - chars of trichomonas infx
-
-protozoan parasite inhabits vagina/urethra
-transmit during sex
-women: copious foul-smelling discharge, increased pH with actively motile trophozoites
-men: assymptomatic - what causes bacterial vaginosis
- gardnerella vaginalis plus anaerobic infx of bacteroides that disrupt normal acidity of vagina
- sx in women:
-
-excessive fish-odored discharge
-pH >4.5
-clue cells (vaginal epithelial cells coated w/ bacteria) - cause of genital herpes
- HSV2
- when is primary lesion seen
- 3-7 days after infx
- pathogenicity:
- healing up to 2 weeks, but virus travels up sensory nerve and establishes latent infx in dorsal root ganglion neurons where it can reactivate and cause a recurrent lesion
- spread from mom to infant?
- yes, during delivery and can give rise to disseminated herpes or encephalitis
- cause of genital warts
- HPV- papillomavirus 6,11,12,16,18,and 31
- where/when do warts appear
- on penis, vulva, and perianal regions after 1-6 mos incubation
- cervical lesion description:
- a flat area of dysplasia visible by colposcopy as a white plaque after local application of 5% acetic acid
- which are associated with cervical cancer
- 16 and 18
- HIV infects which cells
- TH, monocytes and dendritics
- pathogenesis
-
-clings tight to hairs, takes up to 10 blood feedings/day causing itching
-eggs attached to hairs, lice are visible at base of hair
-infestation is common - mechanisms of immunosuppression:
-
1. Th cells are directly killed by virus
2. Th cells undergo apoptosis
3. Th cells are attacked by Tc cells
4. T cell replenishment is impaired by thymus/lymph node damage and stem cell infx
5. defects in antigen presentation (infx of dendritics)
6. antigenic variation in hypervariable region of gp120 - how does viral invasion of CNS occur
- independently of AIDS
- which are the infected cells in CNS
- microglia or infiltrating macrophages which express CD4
- this is seen in about 21% of homosexual/bisexual males and is associated with human herpes virus 8 (HHV8)
- kaposis sarcoma
- what is a major source of transmitted virus
- peripheral blood mononuclear cells
- what are sn of initial infx
- mild mononucleosis type illness including fever and malaise
- are antibodies detectable right away
- no- may take many months; also many mos for t-cells to form
- what happens to viral replication after initial infx
- it's reduced and individual remains well
- sn/sx in later years
- weight loss, fever, persistent lymphadenopathy, oral candidiasis, diarrhea, ARC-AIDS related complex
- what occurs with ARC
-
-less than 10% may be well
-may develop AIDS (opportunistic infxs_
-may develop subacute encephalitis and dementia - AIDS dementia=
- opportunistic CNS infxs like HSV, CMV, and toxoplasmosis
- lab tests for HIV
-
-ELISA
-western blot, radioimmunoassay, or immunofluorescence testing to confirm - odds of getting HIV after needle stick
- <1%
- what types of HIV vaccinations are being developed
- various subunit envelope glycoproteins and a whole virus vaccine
- whats the problem?
- a vaccine that will induce abs against gp120 may combine w/ the virus w/o neutralizing it.....it then attaches to the Fc receptors on monocytes and the whole complex is ingested and monocyte is now infected
- cause of pubic or crab lice
- phthirus pubis
- cause of genital scabies
- Sarcoptes scabei
- whats the most common outcome of GI tract infxs
- diarrhea
- gastroenteritis:
- nausea, vomiting, diarrhea, abdominal discomfort
- diarrhea:
- abnormal fecal discharge- frequent fluid stool; disease of sm intestine
- dysentery:
- inflammatory disorder of GI tract associated w/ blood and pus in feces; accompanied by fever, pain, abdominal cramps; disease of lg intestine
- enterocolitis:
- inflammation involving mucosa of both small and large intestine
- Bacterial causes of diarrhea:
- E. coli, Salmonella, campylobacter jejuni, helicobacter pylori, vibrio cholerae, shigella dysenteriae, shigella sonei, vibrio parahemolyticus, yersinia enterolytica, c. perfringens, b. cereus, staph aureus, c. botulism
- What are the 4 types of E. coli:
-
1. Enterotoxigenic (ETEC)
2. Enteroinvasive (EIEC)
3. Enterohemoerrhagic (EHEC)
4. Enteropathogenic (EPEC) - which is the most imp bacterial cause of diarrhea in children in developing countries and the most common cause of travelers diarrhea
- ETEC
- most important in developed countries but outbreaks an sporadic cases occur worldwide:
- EHEC
- important cause of diarrhea in areas of poor hygiene, usually food borne infxs:
- EIEC
- spread via water contaminated by human or animal sewage:
- ETEC
- causes sporadic cases of infx in babies and young children:
- EPEC
- caused by verotoxin-producing serotype 0157 that has direct affect on intestinal epithelium:
- EHEC
- produces powerful enterotoxins (LT and ST):
- ETEC
- which of these toxins is heat labile
- LT
- heat stable
- ST
- has a mechanism of adhesion to enterocytes that appears to destroy microvilli
- EIEC
- caused by food and unpasteurized milk:
- EHEC
- prevention:
- chlorination and water filtration
- what is the most common case of food-associated diarrhea in developed countries
- salmonellae
- salmonella and e. coli are both:
- enterobacteria
- salmonella transmission:
- animal resevoir- transmitted via contaminated poultry and dairy
- frequent waterborne transmission?
- no
- where do they invade?
- epithelial cells of terminal portion of small intestine
- which species are responsible
- s. enteritidis, s. cholera suis
- which bacteria are S-shaped curved rods
- campylobacter
- how acquired?
- via contaminated milk, poultry, H20
- which bacteria is associated with over 90% of duodenal ulcers and 70-80% of gastric ulcers
- helicobacter pylori
- what does it produce that helps it survive acid environments
- urease
- acute infx of GI tract caused by comma-shaped gram-negative bacteria
- cholera
- species?
- vibrio cholerae
- reservoir and spread?
-
-a free living inhabitant of fresh water
-assymptomatic humans major resevoir
-spread via contaminated food (fresh water shellfish) - which condition is also known as bacillary dissentery?
- shigellosis
- its most severe form is characterized by:
-
-invasion of the mucosa of lg intestine
-inflammation of intestines
-blood/pus in diarrhea
-lower abdomen cramps - which species causes mild infxs?
- shigella sonnei
- severe?
- shigella dysenteriae
- a halophilic organism that contaminates seafood and fish; causes diarrhea if eaten uncooked:
- Vibrio parahemolyticus
- primarily a pediatric disease:
- shigellosis
- rice water stool:
- cholera
- causes infx in colder parts of the world:
- Yersinia enterolytica
- Tx includes omeprazole with amoxicillin and metronidazole:
- H. pylori
- enterotoxin producing type A strain and beta-toxin producing type C strains:
- C. perfringens
- which are more common and caused by spores that contaminate food?
- A strains
- characteristics of type c strains:
-
-acute necrotizing disease of sm. intestine
-more rare
-abdominal pain/diarrhea - prevention?
- thoroughly re-heating food
- which disease has a long standing history of epidemics and pandemics
- cholera
- most common cause of diarrhea:
- Campylobacter jejuni
- clinically, which other bacteria is indistinguishable from c. jejuni?
- salmonella
- caused by eating contaminated meat in people who are unaccustomed to high protein diets:
- C. perfringens
- why?
- lack sufficient intestinal trypsin to destroy the toxin
- a heat stable enterotoxin thats resistant to degradation by enzymes in stomach/ sm. intestine:
- staph aureus
- spores and vegetative cells contaminate food:
- B. cereus
- 2 forms of B. cereus:
-
1. ingestion of enterotoxin in food (rice and potatoes)
2. production of enterotoxin in gut - which causes rapid onset vomiting and which causes diarrhea?
-
vomiting= ingestion
diarrhea= production in gut - found in rabbits, pigs, sheep, cattle, horses, domestic pets:
- yersinia enterolytica
- an acute but self-limiting diarrhea that's resolved without tx:
- salmonella
- diarrhea not a feature, vomiting occurs 3-6 hrs after consumption and recovery w/in 24 hrs:
- staph aureus
- spores are found widespread in the environment and can be isolated from soil samples, animals, and fish:
- clostridium botulinum
- is botulin an exotoxin or endotoxin?
- exotoxin
- how does it invade?
- toxins are ingested in food (canned or reheated) or are produced in the gut after ingesting the organisms
- pathogenesis:
- produces 2 exotoxins that produce diarrhea and lead to colitis
- 3 types:
-
1. foodborne (toxin released in food, then ingested)
2. infant (organism ingested)
3. woulnd (organism implanted in wound) - Causes antibiotic associated diarrhea- broad spectrum antibios that inhibit normal flora:
- Clostridium difficile
- how is viral diarrhea distinguised from bacterial?
- clinically indistinguishable
- viruses:
- Rotavirus and Calcivirus
- which includes the Norwalk virus?
- Calcivirus
- Who does rotavirus mostly infect
- children under 2
- incubation period:
- 1-4 days
- where does viral replication occur?
- intestinal epithelial cells
- Protozoa that cause diarrhea:
- Entamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum
- how does infx occur with E. histolytica
- food/drink is contaminated with cysts that pass thru the stomach and excyst in the sm. intestine where they multiply
- chars. of amebic dysentery:
- mucus, pus and blood in stool
- difference between amebic dysentery and bacillary dysentery:
- amebic can perforate small intestine (peritonitis) and invade extra-intestinally when trophozoites spread via blood to the liver and form an abcess
- Which protozoa causes infx when cysts are swallowed in contaminated drinking water from rivers/streams?
- Giardia lamblia
- animal host?
- beaver
- Pathogenesis of Cryptosporidium parvum:
-
-fecally contaminated material is ingested
-cysts release infective trophozoites which invade epithelial cells in sm. intestine
-parasite found in many animals - cryptosporidiosis:
- common infx in AIDS; diarrhea can be irreversible and life threatening
- which protozoa is common in subtropical and tropical countries
- Entamoeba histolytica
- What are the most important intestinal worms?
- soil transmitted nematodes
- 2 groups of them:
-
1. Ascaris lumbricoides/Trichuris trichiura
2. Anchylostoma duodenale/Necator americanus/Strongyloides stercoralis - large roundworm:
- ascaris lumbridcoides
- whipworm:
- Trichuris trichiura
- hookworm:
- Necator americanus
- which occur by swallowing infective eggs which hatch in intestine and release larvae
- Ascaris and Trichuris
- which can cause abdominal pain and nausea
- Ascaris
- what happens if there's large numbers of ascaris
- can cause intestinal blockage and perforations of wall
- What can Tricuris infx lead to?
- chronic diarrhea and impaired nutrition/retarded growth (since children mostly affected)