INFECTIOUS DISEASES Flashcards
4 classes of beta lactams
penicillins
cephalosporins
carbapenems
aztreonam
which of the following is the most accurate infectious disease test?
protein level of fluid culture igM level IgG level gram stain tx response
culture
bacteria covered by amoxicillin
HELPS
h influenzae, e coli, listeria, proteus, salmonella
what are the 4 penicillinase-resistant penicillins?
what are they used for?
what do the NOT treat?
oxacillin, cloxacillin, dicloxacillin, nafcillin
used for skin infections (impetigo, cellulitis, erysipelas), osteomyelitis, and staph meningitis/bacteremia/endocarditis
not active against MRSA or enterococcus
when is methicillin the right answer? why?
never!
it causes renal failure from allergic interstitial nephritis
what do you combine with piperaicllin or ticarcillin and why?
tazobactam or clavulanic acid
which are beta lactamase inhibitors
which of the following covers for MRSA?
nafcillin cefazolin pip-tazo ceftaroline azithromycin
ceftaroline
the only cephalosporin that covers mrsa!
the only abx that cover mrsa are:
vancomycin daptomycin ceftaroline linezolid tigecycline
+ lesser known: tedizolid, dalbavancin, telavancin
if a case describes a rash to penicillins, the answer is…
if a case describes anaphylaxis to penicillins, you must use…
a cephalosporin
a non beta-lactam abx
rattle the cephalosporins off: 1st gen 2nd gen 3rd gen 4th gen 5th gen
1 - cefazolin, cephalexin, cephadrine, cefadroxyl
2 - cefotetan, cefoxitin, cefaclor, cefprozil, cefuroxime, loracarbef
3 - ceftriaxone, cefotaxime, ceftazidime
4 - cefepime
5 ceftaroline
methicillin sensitive really means….
oxacillin sensitive
which means cephalosporin sensitive!
2nd gen cephalosporins
cefotetan, cefoxitin, cefaclor, cefprozil, cefuroxime, loracarbef
same coverage as 1st gen but more gram - and anaerobes
out of all the cephalosporins, which cover anaerobes?
only cefotetan and cefoxitin (2nd gen!)
3rd gen cephalosporins
which covers pseudomonas?
ceftriaxone, cefotaxime, ceftazidime
ceftazidime covers pseudomonas
1st line tx for pneumococcus/gonorrhea?
ceftriaxone
why do you have to avoid ceftriaxone in neonates?
impaired biliary metabolism
4th gen cephalosporins
cefepime
better staph coverage
used for ventilator ass. pna and neutropenia/fever
5th gen cephalosporins
ceftaroline
covers gram - bacilli and MRSA
NOT pseudomonas
adverse effect of cefoxitin and cefotetan?
increase risk of bleeding by depleting prothrombin
how does ertapenem differ from other carbapenems?
it does NOT cover pseudomonas
aztreonam
monobactam class used only for gram - bacilli INCLUDING pseudomonas
no cross reaction with penicillin
which of the following is most likely to be effective for morganella or citrobacter?
tedizolid dalbavancin ertapenem oritavancin erythromycin
ertapenem
good against gram -
morganella and citrobacter are gram -
the other first 4 abx are used for gram + cocci and mrsa
erythromycin has no useful gram - coverage
fluoroquinolones
coverage and uses?
-floxacin
gram - bacilli and pseudomonas
best for CAP
ciproflaxacin for cystitis and pyelonephritis
if used for GI, must be combined w meronidazole to cover for anaerobes (exception moxifloxacin)
what is special about moxifloxacin vs other fluoroquinolones?
it covers anaerobes
can be used as a single agent for GI/diverticulitis
adverse effects of fluoroquinolones?
bone growth abnormalities (kids/pregnancy)
tendonitis/achilles rupture
adverse fx from aminoglycosides?
ototoxicity
nephrotoxicity
nitrofurantoin has 1 use…
cystitis in pregnant women
doxycycline
uses
side fx
uses: chlamydia, limited Lyme, ricketsia, mrsa, syphilis for penicillin allergic, berrelia, erlichia
side fx: tooth discoloration, photosensitivity, Fanconi (type 2 RTA), esophagitis/ulcer
trimethoprimsulfamethoxazole
mechanism?
uses?
side effects?
mech: folate antagonist
uses: cystitis, pneumocystis pneumonia tx and ppx, mrsa cellulitis
fx: bone marrow suppression, hemolysis (in those with G6PD deficiency), and rash
in general, which abx class has highest efficacy?
penicillins
linezolid can cause reversible….
bone marrow toxicity
Px with perforated bowel, fever and hypotension; anaerobic culture growing an organism; which is most appropriate to start while waiting for results?
aztreonam pip-tazo oxacillin cefepime doxycycline vancomycin
pip tazo
only one that covers anaerobes from the list
all beta lactam/lactamase inhibitor combos cover for anaerobes with equal efficacy to metronidazole
do carbapenems cover GI tract?
YES, they cover gram - bacilli and anaerobes
preferred abx for anaerobes
- above the diaphragm?
- Abdominal/GI?
above: penicillin (G, VK, ampicillin, Amoxicillin) or clindamycin
below: metronidazole or betalactam/lactamase combos
which is best for e coli bacteremia?
vancomycin linezolid quinolones, aztrenam, aminoglycosides, carbapenems, pip/tic doxycycline oxacillin clindamycin
quinolones, aztrenam, aminoglycosides, carbapenems, piperacillin, ticarcillin
ALL COVER GRAM - BACILLI
the others dont
what is the most likely diagnosis:
1) meningeal signs in AIDS px with <100 CD4
2) camper/hiker, targetoid rash, joint pain, facial palsy, +/-tick
3) camper/hiker, migratory rash, +/-tick
4) adolescent with petechial rash
1 - cryptococcus
2 - lyme dz
3 - rickettsia (rocky mtn spotted fever)
4 - neisseria
for meningitis, the best and most accurate initial test is…
Lumbar puncture
what will LP show (cell count, protein, glucose, culture)
1) bacterial meningitis
2) cryptococcus, Lyme, rickettsia
3) TB
4) viral
1 - 1000s neutrophils, high, low, often +
2 - lymphocytes, possible high, possibly low, negative
3 - lymphocytes, very high, maybe low, negative
4 - lymphocytes, normal, normal, negative
for meningitis, when is head CT the best initial test?
necessary BEFORE LP only if there is chance of a space occupying lesion that may cause herniation
aka when these signs are present:
papilledema (blurred disc margin d/t intracranial P)
seizures
focal neuro deficits
confusion interfering with neuro exam
if there is contradiction to immediate LP, what is best initial step?
give abx (better to treat and decrease accuracy of test, than to risk permanent brain damage)
when is a bacterial antigen test (latex agglutination) indicated?
if +, extremely specific
if -, doesnt rule ifx out (not sensitive enough to exclude)
use when patient has received abx prior to the LP and culture might be falsely negative
advantage is that this test will not become negative after a few doses of abx!!
What is the most accurate test for TB?
acid fast stain and culture on THREE CENTRIFUGED LPs
what is the most accurate test for lyme/rickettsia?
specific serology, elisa, PCR, western blot
what is the most accurate test for cryptococcus?
CULTURE (100 % specific)
cryptococcal antigen is >95% sens/spec
india ink is only 60-70%
if patient is confused and cant do neuro exam, which do you get first: LP or CT?
CT
best treatment for bacterial meningitis?
vancomycin, ceftriaxone, and steroids (dexamethasone)
**add ampicillin if immunocompromised for listeria
additional management for neisseria meningitidis?
respiratory isolation
and
ppx to close contacts (those with resp fluid contact, to decrease nasopharyngeal carriage) = rifampin, ciproflaxacin, or ceftriaxone
a man comes to the ED with fever and meningeal signs with specific neuro deficit on exam; what is next step?
TREAT with ceftriaxone, vanc, and steroids
since there in an immediate contraindication to LP, abx come first BEFORE CT
most common cause of encephalitis (acute onset fever and confusion)?
herpes simplex
what is the most accurate test for herpes encephalitis?
pcr of csf brain biopsy mri viral culture of csf tzanck prep serology IgG igM
PCR of CSF
it is better than biopsy, serology will be + for most so useless, tzanck prep is first test for genital ulcer, viral culture is most accurate for skin lesions but not for csf/brain
first step in encephalitis evaluation?
best initial therapy?
CT due to presence of
acyclovir (since it is IV form)
foscarnet can be used for acyclovir resistant forms
woman admitted for herpes encephalitis confirmed by PCR, after 4 days of acyclovir her Cr begins to rise – what is next step?
reduce dose and hydrate
do not switch to foscarnet because it only has worse renal toxicity, do not switch to famciclovir or valacyclovir because oral abx is insufficient
which is the most sensitive physical finding for otitis media?
immobility – mobile TMs basically exclude otitis media
what is the most accurate test for otitis media?
what is the best initial tx? next tx?
tympanocentesis (if multiple recurrences or unresponsive to tx)
amoxicillin –> amox/clav, azitrhomycin, clarithromycin, cefuroxime, or guinolones(NOT in kids)
a 34 yr old woman with facial pain, discolored nasal discharge, bad taste in mouth, and fever….what is most accurate diagnostic test?
sinus biopsy or aspirate ct scan xray culture of discharge transillumination
sinus biopsy or aspirate!
NEVER do a culture of nasal discharge
usually only needed however in recurrence or when unresponsive to tx
a 34 yr old woman with facial pain, discolored nasal discharge, bad taste in mouth, and fever….what is next appropriate step?
linezolid ct scan xray amox/clav and decongestant erythromycin and decongestant
amox/clav and decongestant
when dx is clear, ct is unecessary
erythromycin doesnt cover strep pneumo well
linezolid wouldnt cover h influenzae
best initial test for pharyngitis (pain swallowing, exudate, fever, no cough)?
tx?
rapid strep test
(group A beta hemolytic strep)
penicillin or amoicillin
- -rash treated with cephalexin
- -anaphylaxis –> use clindamycin or macrolide instead
pharyngitis with membranous exudate?
diphtheria
influenza tx
if less than 48 hrs of sx: oseltamivir or zanamivir (neuraminidase inhibitors to shorten duration)
if more than 48 hrs, sx treatment only (analgesic, rest, hydration, antipyretic)
infectious diarrhea - best initial test?
most accurate test?
stool lactoferrin has highest senx/spec
second best is fecal leukocytes
most accurate = stool culture
causes of infectious diarrhea when there is blood or WBCs in stool:
1 poultry?
2 most common cause?
3 associated with HUS?
4 shellfish and cruise ships?
5 shellfish, hx of liver dz, skin lesions
6 associated with iron, hemachromatosis, blood transfusions
7 white and red cells in stool?
1 salmonella 2 campylobacter 3 e coli 0157:H7 and shigella 4 vibrio parahaemolyticus 5 vibrio vulnificus 6 yersinia 7 clostridium dificile
causes of infectious diarrhea when there is NOT any blood or WBCs in stool? 1 associated with vomiting? 2 vomiting after rice? 3 ADIS <100 cd4 4 unfiltered water while camping 5 nonbacterial
1 staphylococcus or bacillus cereus 2 bacillus cereus 3 cryptosporidiosis 4 giardia 5 viral
scombroid poisoning
sx?
tx?
rapid onset diarrhea, wheezing, flushing, rash
found in fish
tx w antihistamines
which is most accurate in finding the etiology of infectious diarrhea?
hx of eating chicken frequency blood in stool odor recent interstate travel
blood in stool
tells us it is invasive (shigella, salmonella, yersinia, or e coli)
specific tx for infectious diarrhea:
1) giardia
2) cryptosporidiosis
3) viral
4) b cereus/staph
1 - metronidazole
2 - treat AIDS and nitazoxanide
3 - fluids
4 - fluids
which hepatitis is dependent on ifx by hep B?
hep D
which hepatitis is the worst in pregnancy?
hepatitis E
which hepatitis is passed via water/food?
via blood/sex/perinatal?
A and E
B,C,D
in hepatitis, which best correlates with increased likelihood of mortality?
bilirubin prothrombin time ALT AST Alk phos
prothrombin time
increases risk of fulminant hepatic failure and death
serology patterns for hep B:
1) acute or chronic ifx
2) resolved or old ifx
3) vaccination
4) window period
1 + surface antigen, + e antigen, +IgM or IgG core antibody, - surface antibody
2 - for surface antigen and e antigen, + igG core antibody, + surface antibody
3 - for surface and e antigen, - for core antibody, + for surface antibody
4 - for surface and e antigen, - for surface antibody, + for IgM and then IgG core antibody
which of the following becomes abnormal FIRST after acquiring Hep B?
bilirubin e antigen surface antigen core igM antibody alt e antibody
surface antigen
= a measure of actual viral particles
histoplasma capsulatum
dimorphic fungi
soil/bat droppings in mississippi and ohio
granulomas, hilar adenopathy
can imitate sarcoidosis; will deteriorate after immunosuppressive therapy
Which hepB marker most closely correlates w amount or quantity of active viral replication?
e antigen
correlates w amount of Dna polymerase
what indicates that a px is no longer a risk for transmitting hep B ?
no surface antigen
even if antbody is present, as long as surface antigen is there - there is a chance of active replication
what hep B marker indications need for treatment with antiviral?
e antigen
= level of polymerase
surface antigen indicates active replication but not wether it is resolves or building up
which acute hepatitis has medical tx available?
what is it?
acute hepatitis c –> tx with interferon, ribavirin, and either telaprevir or boceprevir
how often does hep B become chronic?
chronic is defined by…
10%
surface antigen for more than 6 months
interferon is rarely used as first line for chronic hepatitis, why?
what is better?
it is an injection with lots of side effects: arthralgia, myalgia, leukopenia, thrombocytopenia, depression, flu like sx
sofosbuvir
if you are going to treat hepatitis based on viral load, do you need to do a liver biopsy?
no
cervical discharge + strawberry cervix
dx?
tx?
cervicitis
dx: with swab/NAAT
tx: ceftriaxone and azithromycin
lower abdominal pain, tenderness and cervical motion tenderness +/-fever, leukocytosis
next appropriate step?
dx?
tx?
PID
next step: exclude pregnancy
dx: cervical swab (**laparoscopy is most accurate test however; used when unclear/recurrent)
tx: treat for chlamydia/gonorrhea
for patients with penicillin anaphylaxis, how do you treat PID (chlamydia/gonorrhea)?
levofloxacin and metronidazole as outpatient
or
clindamycin, gentamicin, and doxycycline as an inpatient
most likely STD?
1) painLESS ulcer
2) painFUL ulcer
3) LNs tender and supurative
4) vesicles prior to ulcer and painful
1 syphilis
2 chancroid (haemophilus ducreyi)
3 lymphogranuloma venereum
4 herpes simplex
best initial test for herpes simplex?
most accurate test for herpes simplex?
best initial = tzanck prep
most accurate = viral culture
treatment for
1) syphilis
2) chancroid (haemophilus ducreyi)
3) lymphogranuloma venereum
4) herpes simplex
1 single dose IM benzathine penicillin (or doxycycline if allergic)
—for tertiary (neurosyph) –> IV penicillin (desensitize if allergic or pregnant)
2 single dose azithromycin
3 doxycycline
4 oral acyclovir (valacyclovir/famciclovir) or foscarnet for acyclovir resistant herpes (topical is worthless)
woman comes in with multiple painful genital vesicles…next step in management?
acyclovir orally
tzanck prep/diagnostic testing is not needed if the presentation is clear
differentiate between primary, secondary, and tertiary syphilis?
primary = painless genital ulcer with heaped up indurated edges and painless adenopathy
secondary = rash on palms and soles, alopecia areata(patchy hair loss), condyloma lata
tertiary = neurosyphilis
- –memory/personality change
- –argyll robertson pupil (reacts to accomodation but not light)
- –tabes dorsalis (loss of position and vibratory, incontinence, and cranial nerves)
- –aortitis (aortic regurg, aneurysm)
- –gummas (skin and bone lesions)
sensitivity of vdrl/rpr versus fta-abs for syphilis?
vdrl/rpr
75-85% in primary, 99% in secondary, and 95% tertiary
fta-abs (treponemal abs) IS HIGHER
95% in primary, 100% in secondary, and 98% in tertiary
which is the most sensitive test of csf for neurosyphilis?
FTA
nearly 100% in csf
a negative fta of csf effectively excludes neurosyphilis
negative fta = NOT neurosyphilis
what factors can cause a false positive vdrl/rpr?
infection old age injection drug use AIDS malaria antiphospholipid syndrome endocarditis
what is the jarisch-herxheimer reaction and how do you treat?
fever and worse sx after treatment (due to endotoxin like products from organism death)
–seen with syphilis
give aspirin and antipyretics…it will resolve on its own!
treatment for pregnant women with neurosyphilis?
desensitive and then give IV penicillin
treatment for crabs or scabies?
permethrin
(lindane is equal in effectiveness but more toxic)
condyloma acuminata
causative agent?
how to dx?
tx?
genital warts (papillomavirus)
dx SIMPLY BY VISUAL APPEARANCE (no biopsy or culture)
tx: cryotherapy or imiquimod (immunostimulant that doesnt damage skin)
treatment for cystitis?
nitrofurantoin x3 days (7 days if there is anatomic abnormality)
avoid ciprofloxacin to avoid resistance
first line tx for pyelonephitis?
ceftriaxone
or amp/gent or ciprofloxacin
man with pyelonephritis was treated but has persistent fevers 7 days later…next step?
imaging like sonogram or CT
most likely a perinephric abscess
then you would DRAIN it
intiial tx for endocarditis? then specific tx for these bugs: 1 viridans step 2 staph aureus 3 fungal 4 staph epi or resistant staph 5 enterococci
vanc and gent initially
1 ceftriaxone 4 weeks 2 oxacillin or nafcillin 3 amphotericin and valve replacement 4 vancomycin 5 amp and gent
culture negative endocarditis dx criteria
1 major
3 minor
usual causes? tx?
1 oscillating vegetation on echocardiography
2 fever>100.3
3 risks like prosthetic valve or IV drug use
4 signs of embolic phenomena
HACEK (haemophilus, actinobacillus, cardiobacterium, eikenella, kingella) or coxiella or bartonella
ceftriaxone
if endocarditis culture returns as strep bovis or clostridium, next step?
colonoscopy
colon pathology likely!
single strongest indication of surgery in patients with endocarditis?
CHF from acute valve rupture
reasons for surgical intervention for endocarditis?
fungal CHF from acute valve rupture prosthetic valves recurrent emboli while on abx abscess AV block
best ppx for endocarditis prior to surgery?
amoxicillin
most common joint affected in lyme?
most common neuro sx in lyme?
most common cardiac sx in lyme?
knee
bell palsy (7th CN)
transient AV block
dx for lyme dz
if rash is typical targetoid erythema migrans, do not need to confirm with serology –> just treat
if no classic rash, do serology with IgM/G, elisa, western blot, or pcr
lyme tx 1_ asx tick bite 2 - rash 3 - joint sx and bells palsy 4 - cardiac and neuro other than bells
1 no tx
2 doxycycline
3 doxycycline
4 IV ceftriaxone
HIV is what kind of virus? and infects what?
retrovirus
CD4 (t helper) cells
other than mother to child transmission, which risk factor for HIV has highest risk of transmission?
RECEPTIVE anal intercourse
In HIV patients, OI that occurs with CD4 count
1) <500
2) <200
3) <100
4) <50
1 - oral candidiasis, kaposi sarcoma
2 - PCP(pneumocystis pna), PML(prog. multifocal leukoenceph.)/JC virus, cryptosporridium diarrhea
3 - toxoplasmosis, diss. histoplasmosis, candida esophagitis
4 - cryptococcal meningitis, CMV retinitis, diss. MAC
best initial test for HIV?
confirmed with?
best initial for infants?
how to monitor response?
elisa test
confirm with western blot
best initial for infants is pcr or viral culture because elisa is unreliable in baby(maternal HIV ab maybe present for 6 months)
pcr -rna level is also used to monitor response
best ART combo for HIV?
emtricitabine + tenofovir + efavirenz
(E and T are nuceloside reverse transcriptase inhibitors)
(efavirenz is a non nuceloside RTI)
**3 drugs from atleast 2 classes
in ART therapy for HIV, which protease inhibitor can be used with other PIs to boost their level?
ritonavir (TONES up levels)
post exposure prophylaxis for HIV
1) needle sticks and sexual exposure
2) urine and stool exposure?
3) bite from HIV patient
1 - YES, 4 weeks of ART
2 - only therapy if there was blood present
3 - yes ART
adverse effects of ART meds:
1) zidovudine
2) didanosine/stavudine
3) abacavir
4) protease inhibitors
5) indinavir
6) tenofovir
1 - anemia
2 - peripheral neuropathy and pancreatitis
3 - hypersensitivity/Stevens johnson syndrome (HLA B5701)
4 - hyperlipidemia/hyperglycemia
5 - nephrolithiasis
6 - renal insufficiency
should ART be continued in pregancy?
c section?
does baby need anything?
YES, same regimen, regardless of viral load or cd4 count
except for efavirenz (change to a protease inhibitor), this is teratogenic in animals
if viral load is >1000, do a c section
baby receives zidovudine during delivery and for 6 weeks after birth
sporotrichosis
sporothrix schenckii (dimorphic fungus) decaying plant/soil (gardeners)
skin papules, ulcer with nonpurulent odoless drainage and proximal lesions along lymph chains
dx with culture
tx with oral itraconazole
what fungal infection resembles tb but with addition of lytic bone lesions?
dx?
tx?
blastomycosis (mississippi/ohio/wisconsin)
broad based budding!
tx itraconazole or amphotericin B
OIs with AIDS
bugs and ppx tx
<200 PCP, tmp-smx or dapsone
<100 toxo, tmp-smx or pyramethamine/leucovorin
<50 MAC, azithromycin
HIV PREexposurePxx
tenofovir and emcitirabine (both NRTIs)
if PPD is +, next step?
if -?
get chest xray!
if -, no further eval - no tb!
ppd interpretation
what if ppd has been positive before or active sx?
> 5 mm is + for immunocompromised (HIV, close contacts(live at home w person) etc)
> 10 healthcare workers, prison, edemic areas
> 15 average, no risk factors
if ppd have ever been positive or have active sx, you screen with chest xray as INITIAL test
how do you treat tb?
isoniazid + B6 for latent
active = RIPE - rifampin + b6, isoniazid, pyrazinamine, ethambutol
side effects of ripe tx
rifampin –> red body fluids
isoniazid –> peripheral neuropathy
p –> hyperuricemia/gout
ethambutol –> eye problems (r/g color blindness)
sepsis / SIRS criteria
sirs = 2/4 T <36 or >38 wbc <4 or >12 rr >20 hr >90
septic = sirs + source
severe sepsis = organ dysfunction responsive to fluids
septic shock = unresponsive to fluid
where in brain does hsv present?
temporal lobe
tx for inpatient necrotizing fasciitis (gas in skin on xray/spreading?)
debridement then abx
3rd gen cephalosporin + clinda + ampicillin
mc cause of osteomyelitis is always
staph aureus
measles vs german measles(rubella)
which have have arthralgias?
rubella!
