Infectious medicine Flashcards

Terms Definitions
gram+ catalase+ cocci
coagulase+: stah aureus
caogulase-: staph epidirmidis (novobiocin sens), staph saprophyticus (novobiocin res)
gram+ catalase- cocci
alpha hemolytic -->
pneumococcus (optochin sens)
viridans (optochin res)

beta hemolytic -->
group A strep pyogenes (bacitracin sens)
group B stret agalactiae (bacitracin res)
gram+ rods
bacillus, clostridium, corynebacterium, listeria
gram- cocci
meningococcus (maltose fementer), neisseria gonorrheae (maltose non fermenter)
gram- cocobacillus
gram- rods
lactose fermenters --> e. coli, klebsiella
lactose nonfermenter oxidase- --> salmonella, shigella, proteus
lactose nonfermenter oxidase+ --> campylobacter, pseudomonas, vibrio, H. pylori
DNA viruses
HHAPPPPy: herpes, hepadna, adeno, parvo, papilloma polyoma, pox
RNA+ viruses
Calici (Norwalk), PEeCoRnA, Flavi (hepC, dengue, yellow fever, WNV), Toga (rubella), Corona, Retro. "Call Pico and Flava To Come Rap"
RNA- viruses
PaRaMyxo, Rhabdo, Arena, Filo, Orthomyxo (influenza), Bunya, Delta
"Para Rabiar in the Arena, Fill OR Buny"
Togavirus, flavivirus, bunyavirus
meningitis etiology
bacterial: pneumococcus (adults), mningococcus (children/adolescents), agalactiae (neonates)
listeria is more common in immunosupressed
staph aureus (neurosurgery)
cryptococcus (HIV)
RMSP (geographic)
Lyme (borrelia, geographic)
TB, syphilis
viral: coxackie, HIV, herpes simplex
meningitis presentation
photophobia, headache, nuchal rigidity
fever, nausea, vomitting
altered mental status, seizures, neurological deficits (specially CN VIII)

petechial rash (meningococcus)
writs/ankle centripetal rash (RMSF)
facial nerve palsy (Lyme)
abnormal chest x-ray (TB)
meningitis diagnosis
lumbar puncture is initial procedure
if papilledema, focal motor deficits, seizures, mental status changes, or HIV --> do CT of head first

CSF analysis:
↑WBCs (neutrophils) --> bacterial;
↑WBCs (lymphocytes) --> viral, ricketsia, Lyme, TB, syphilis;
↑proteins (mostly in bacterial, but any)
↓glucose (mostly bacterial)

Lyme and RMSF have specific serology
cryptococcus detect with India ink test and serum/CSF cryptococcal antigen
syphilis with VDRL or FTA-ABS
TB with culture or PCR
meningitis treatment
empirical: vancomycin + ceftriaxone +- ampicillin (HIV, steroids, pregnancy or malignancies)

listeria is resistant to all cephalosporins
vancomycin if resistant pneumococcus
Lyme --> ceftriaxone
cryptococcus --> amphotericin + fluconazole
neurosyphilis --> high-dose penicillin

dexamethasone as adjuvant in bacterial meningitis
encephalitis etiology
most commonly by HSV-1
also by VZV, CMV, coxackie and encephalitis viruses
HSV-1 has predilection for temporal lobes
encephalitis presentation
altered mental status with fever and headache are main clues; can also have stiff neck
encephalitis diagnosis and treatment
due lumbar puncture first
PCR of CSF is sensitive and specific for HSV-1
CT or MRI to exclude other diseases and may see temporal lobe involvement
IV acyclovir or gancyclovir/foscarnet for CMV
brain abscess etiology
organisms spread to brain from
otitis media, sinusitis, mastoiditis, dental infections, endocarditis, pneumonia, HIV

most common -->
strep pneumonia (60-70%)
bacteroides (20-40%)
enterobacteriacea (25-35%)
staph (10%)
toxoplasmosis in AIDS
can often by polymicrobial
brain abscess presentation
headache is most common symptom
focal neurologic deficits (60%)
brain abscess diagnosis
initial test is contrast CT
MRI is more accurrate
precise etiology is with examination of abscess fluid
90% of HIV brain abscess is from toxoplasma or lymphoma and diagnosis is made if it responds to 10-14 days with pyrimethadine or sulfadiazine
brain abscess treatment
stereotactic aspiration (preferred) or surgical excision

antibiotics are also given in combination depending on etiology
if toxoplasmosis --> pyrimethadine and sulfadiazine
else give combo; example: penicillin for strep, metronidazole for anaerobes and third-gen ceph for gram-
otitis media etiology
preceeded by viral upper respiratory infection with edema of eustachian tube
strep pneumo (35-40%)
H. influenzae (25-30%)
moraxella (15-20%)
rest is viral etiology
same breakdown as sinusitis and bronchitis
otitis media presentation
ear pain
decreased hearing
red bulging tympanic membrane on physical
otitis media diagnosis
physical exam of ear
otitis media treatment
amoxicillin is DOC
can also use second-gen ceph
penicillin allergies --> azi/clarithromycin
quinolones have broader spectrum than required
sinusitis etiology
strep pneumo (35-40%)
H. influenzae (25-30%)
moraxella (15-20%)
rest is viral etiology
same breakdown as otitis media and bronchitis
sinusitis presentation
facial pain, headache, postnasal, purulent drainage; fever in 50%
sinusitis diagnosis
clinical diagnosis
routine imaging is not recommended
if in doubt or no response to treatment --> CT
sinus puncture may be necessary
sinusitis treatment
if mild or uncomplicated --> oral pseudoephedrine, oxymetazoline
if severe --> amoxicillin is DOC
can also use second-gen ceph
penicillin allergies --> azi/clarithromycin
viral sinusitis resolves within 10 days with symptomatic treatment (antihistamines, NSAIDs, decongestants)
pharyngitis etiology
majority are viral
S. pyogenes is only 15-20% but is most important due to complications
pharyngitis presentation
sore throat
cervical adenopathy
pharynx inflammation and exudate are suggestive of S. pyogenes (or EBV)
horaseness and cough are not suggestive of pharyngitis
pharyngitis diagnosis
rapid strep antigen test are unsensitive but specific and diagnostic but absence doesn't exclude
pharyngitis treatment
penicillin; macrolides if allergic
influenza A or B virus leads to coryza, nonproductive cough, sore throat, conjunctival injection and systemic symptoms as fever, myalgia, headache and fatigue

diagnosis confirmation is with rapid antigen detection

treat symptoms with acetaminophen and antitussives
specific treatment is oseltamivir and zanamivir
vaccination is recommended in older than 50, lung or cardiac diasease, immunosupressed, diabetics
bronchitis etiology
vast majority are caused by viruses
then strep pneumo, nontypable Haemophilus, moraxella, mycoplasma
cigarette smoke is predisposing factor
bronchitis presentation and diagnosis
cough and sputum production with normal x-ray confirms diagnosis
lungs are clear to auscultation
fever may occur
bacterial etiology is suggested by discolored sputum
bronchitis treatment
mild cases require no treatment
acute exacerbations of chronic bronchitis are treated with amoxicillin, doxycycline or TMP-SMX
repeated infections: amoxicillin/clavulanate, clarithromycin, azithromycin, 2nd or 3rd-gen cephs or quinolones
lung abscess etiology
90% have oral anaerobes peptostrep, prevotella and fusobacterium
45% only anaerobic, 45% mixed, 10% aerobes
aerobics found are staph, e. coli, klebsiella, pseudomonas
associated oral periodontal disease or predisposition to aspiration
lung abscess presentation
fever, cough, sputum, chest pain, putrid odor, chronic course with weight loss, anemia, fatigue
lung abscess diagnosis
sputum Gram stain will not show anaerobes
chest x-ray may show cavitary lesion most commonly in lower lobes or posterior segmenet of right upper lobe
aspiration and analysis of abscess fluid confirms
lung abscess treatment
empiric drug is clindamycin; drainage is not required
pneumonia etiology
in children <5 viruses are most common
older than 5, pneumococcus is leading cause
typical agents (40-60%) S. pneumoniae, Haemophilus, moraxella
atypicals: legionella, mycoplasma, chlamydia
pneumonia predisposing factors
cigarette smoking, diabetes, alcoholism, malnutrition, obstruction from tumors, immunosupression
pneumonia associations: haemophilus
smokers and COPD patients
pneumonia associations: mycoplasma
atypical presentation in young otherwise healthy patients
pneumonia associations: legionella
epidemic; older smokers
associated with infected water sources and air conditioning systems
pneumonia associations: pneumocystis jiroveci
HIV+ <200 CD4
pneumonia associations: coxiella
Q fever; exposure to animals specially specially when they are giving birth
pneumonia associations: klebsiella
pneumonia associations: staph aureus
following viruses or viral bronchitis, specially influenza
pneumonia associations: coccidioidomycosis
southwestern deserts
pneumonia associations: chlamydia psittaci
pneumonia associations: histoplasma
bird droppings and spelunking
pneumonia associations: bordetella
cough with inspiratory whoop and post-tusive vomitting
pneumonia associations: francisella
hunters or exposure to rabbits
pneumonia associations: SARS/avian flu
travel to south east asia
pneumonia associations: anthrax, yersinia, francisella
pneumonia presentation
cough, fever, sputum production, pleuritic chest pain, tachypnea
viral and atypicals produce a non-productive dry cough

on physical: rales, ronchi, dullness to percusion, bronchial breath sounds, increased fremitus, egophony

bacterial sputum is purulent and can be mixed with blood (rusty, pneumococcus) or blood and mucous (currant-jelly, klebsiella)
pneumonia diagnosis
chest x-ray is first --> localized or diffuse infiltrates and alveolar or interstitial pattern
next --> sputum Gram stain and culture (most specific for lobar pneumonia)
atypicals don't show in Gram stain or culture

mycoplasma --> cold agglutinins
legionella --> antigen tests and charcoal yeast culture
pneumocystis --> increased LDH in bronchoalveolar lavage
chlamydia pneumonia, coxiella, coccidiodes all have specific antibody titers
pneumonia major severity signs
hypoxia (PO2<60mmHg)
O2 saturation <94%
respiratory rate >30/min
confusion, uremia, hypotension
pneumonia minor severity signs
high fever
pulse >125/min
dehydration determined by high BUN
empiric treatment for pneumonia outpatients
azithromycin or clarithromycin are DOC
alternative are levofloxacin, moxifloxacin, gatifloxacin
empiric treatment for pneumonia inpatients
new quinolones OR 2nd/3rd gen ceph with macrolide or doxyclycline
empiric treatment for hospital-acquired pneumonia
3rd gen ceph with antipseudomonal activity OR imipenem OR piperacillin/tazobactam
should also cover MRSA with vancomycin or linezolid
haemophilus pneumonia specific treatment
2nd or 3rd gen ceph
mycoplasma pneumonia specific treatment
macrolides, doxycycline or new quinolone
legionella pneumonia specific treatment
macrolides, doxycyline or new quinolone
pneumocystis pneumonia specific treatment
add steroids if PO2<70mmHg or A-a >35mmHg
if allergic to sulfa use IV pentamidine or atovoquone
prophylaxis with dapsone or atovoquone
coxiella pneumonia specific treatment
staph pneumonia specific therapy
oxacillin, nafcillin, etc… if MRSA --> vacomycin or linezolid
coccidioides pneumonia specific therapy
only need treatment if diseminated disease
mild diseasse --> fluconazole or itraconazole
severe disease --> ampB
pneumococcal vaccine indications
older than 65
serious lung, cardiac, liver or renal disease
steroid patients
splenectomized patients
leukemia/lymphoma patients
tuberculosis etiology
25% of world population is exposed; higher risk of exposure in alcoholics, healthcare workers, prisoners, homeless shelters, nursing homes, HIV, steroids, organ transplant, leukemia, lymphoma
tuberculosis presenation
cough, sputum, fever, weight loss, night sweats and abnormal lung exam
may also involve any organ specially lymph nodes, meninges, GI and GU
tuberculosis diagnosis
chest x-ray is best initial test in symptomatic patients, PPD in asymptomatic
x-ray shows apical infiltrates and sometimes cavitations, adenopathy and calcifications (Ghon complex)

acid-fast stain of sputum (3 smears >90% sensitive)
culture is specific and needed for bug sensitivity testing

if acid-fast is unrevealing can do thoracentesis, gastric aspirate in children, biopsy or needle aspiration of organ involved or lumbar puncture in meningitis

pleural biopsy is most sensitive
look for casseating granulomas
tuberculosis treatment
empiric treatment is combo of INH/pyridoxine, rifampin, pyrazinamide, ethambutol for first 2 months or until sensitivty testing; then INH + rifampin for another 4 months

if sensitivity is not known give also ethambutol
TB meningitis add steroids + 12 months
TB in pregnancy 9 months
tuberculosis drugs side effects
all cause liver toxicty except streptomycin
INH --> peripheral neuropathy (give pyridoxine)
ethambutol --> optic neuritis
rifampin --> red/orange metabolites
pyrazinemide --> benign hyperuricemia
PPD test generalities
used to screen asymptomatic populations at risk of TB to see if they have been exposed; consits of intradermal injection of the PPD with induration of the skin 48-72 hours after

if test is <10mm, do a second test to rule out false negative
if positive do chest x-ray and acid-fast stain

positive PPD with no evidence of active disease receive prophylaxis with INH+pyridoxine for 9 months
PPD test > 5mm induration
considered positive if
close contacts of active TB cases
abnormal chest x-ray
steroids or organ transplant
PPD test > 10mm induration
considered positive if
children < 4
leukemia or lymphoma
injection drug users
healthcare worker
immigrants (recent)
nursing home residents

CLIP HINDuration
PPD test > 15mm induration
considered positive for people with no risk factors for TB
food poisoning/infectious diarrhea etiology
campylobacter is most common
salmonella (raw eggs and poultry)
e. coli (traveler's diarrhea, undercooked hamburger meat)
B. cereus (reheated fried rice)
giardia, cryptosporidia (contaminated water)
V. parahemolyticus (contaminated shellfish)
V. fulnificus (raw shellfish)
rotavirus, Norwalk agent (children)
C. difficile (antibiotics)
C. botulinum (canned food)
C. perfringes (unrefrigerated meats)
food poisoning/infectious diarrhea presentation
most importantly is presence of blood and specific symptoms
bloody diarrhea --> salmonella, shigela, yersinia, invasive e. coli, campylobacter
watery diarrhea --> protozoans except entamoeba, clostridium, vibrio, viruses, B. cereus, staph
predominantly nausea/vomitting --> B. cereus, staph
food poisoning/infectious diarrhea diagnosis
if there's no blood in stool then check for leukocytes in stools with methylene blue test
then do culture for specific etiology
for protozoans direct stool examination for parasites or ova
food poisoning/infectious diarrhea treatment
empiric antibiotics until stool culture and if there's abdominal pain, bloody stools and fever or hypotension; high-volume stools and dehydration don't justify antibiotics

empirical treatment is ciprofloxacin or fluoroquinolone+metronidazole

scombroid is treated with antihistamines
giardia with metronidazole
isospora with TMP/SMX
doxycycline for vibrio
acute viral hepatitis presentation
jaundice, dark urine, light-colored stools, fatigue, malaise, weight loss, tender liver, hepatomegaly
indistiguishable from drug-induced hepatitis; hep b and C can also have serum sickness, arthritis, rash; PAN is associated with hep B
acute viral hepatitis diagnosis
all hepatitis gives ↑total and ↑direct bilirubin
ALT > AST in viral
AST>ALT in drug-induced
alkaline phosphatase and GGTP may not be elevated unless canalicular damage
viral hepatitis serology
IgM indicates acute infection with A, C, D or E viruses
IgG antibody to A, C, D or E indicates old, resolved disease
hep C activity is followed with PCR viral load

hep B acute diagnosis: ↑HbsAg, ↑IgM-HbcAb and HbeAg (infectivity)
resolution is indicated by ↓HbsAg, ↑HbsAb, ↑HbcAb-IgG (only marker in window-period), ↑HbeAb-IgG
acute viral hepatitis treatment
ne effective treatment for acute viral hepatitis
chronic hep B --> either interferon, entecavir, adefovir, lamiduvine
chronic hep C --> combo of interferon and ribavirin
treatment for cirrhosis is transplant
after needlestick with hep B and if no adequate levels from vaccine --> HBIg + hep B vaccine;
no post-exposure prophylaxis for hep C
by gonococcus or chlamydia, ureaplasma, mycoplasma, trichomona or HSV
purulent urethral disharge, dysuria, urgency, frequency

diagnose with gram stain showing coffee bean-shaped diplococci or fluorescent antibodies for chlamydia (on urethral swab or urine)

treat with single-dose ceftriaxone IM and single-dose azithromycin orally
pelvic inflammatory disease
gonococcus, chlamydia, mycoplasma, enterobacteria
lower abdominal pain on palpation of cervix, uterus or adnexa
cervical motion tenderness is key
fever, leukocytosis and discharge also

do gram stain of discharge and culture on Thayer-Martin
do pregnancy test
diagnosis is clinical; laparoscopy is definitive
may do culdocentesis or sonography

treat with doxycycline and cefoxitin (inpatient) or single-dose ceftriaxone and doxycyline for two weeks for outpatient
syphilis presentation
primary --> chancre (1-3 weeks) and regional nontender lymphadenopathy

secondary --> cutaneous rashes (6-12 weeks) on flexor areas, lympahdenopathy and condylomata lata (papules at mucocutaneous junctions)

latent stage --> may persist for life

tertiary --> 1/3 of patients, gummas lead to tabes dorsalis and Argyll-Robertson pupil
syphilis diagnosis
screening: VDRL, RPR
specific: FTA-ABS, MHA-TP, darkfield exam
false positive VDRL in EBV, collagen vascular disease, TB, subacute bacterial endocarditis
syphilis treatment
2.4 million units if IM benzathine penicilline given once for primary and secondary and once a week 2 weeks for latent (VDRL >1:8 without symptoms); tertiary is treated with 10-20 million units/day IV for 10 days; if allergic give doxycycline but desensitize for tertiary and pregnancy
caused by Haemophilus ducreyi
small, soft, painful papules that coalesce and become ulcers with ragged edges
tender and enlarged inguinal nodes
diagnosis is clinical
Gram stain and culture to confirm
treat with single-dose azithromycin or ceftriaxone OR erythromycin for 7 days OR cipro for 3 days
lymphogranuloma venereum presentation
small, transient, nonindurated lesion that ulcerates and heals quickly producing unilateral inguinal node enlargement, multiple drainning sinuses that persist or recur; also fever, malaise, joint pains, headaches
lymphogranuloma venereum diagnosis and treatment
clinical diagnosis
high or rising titer of complement fixing antibodies
isolate chlamydia trachomatis from pus in buboes
treat with doxycycline
granuloma inguinale
painless red nodule that turns into elevated granulomatous mass by donovantia granulomatis
looks like conylomata lata or carcinoma
diagnose with Giemsa or Wright stain, punch biopsy
treat with doxycyline or ceftriaxone
gential herpes
vesicles on genital area or mucous membranes that become eroded ulcers with red areola; itching and soreness; can have inguinal lymphadenopathy; diagnose with Tzanck test and culture; treat with acyclovir, famcyclovir, valacyclovir or foscarnet; explain relapsing nature
genital warts
papilloma virus causes condylomata acuminata which are warm, moist, pink pedunculated swellings with cauliflower appearance

clinical diagnosis

treatment: destruction (curettage, sclerotherapy, trichloroacetic acid), cryotherapy, podophyllin, imiquimod, laser removal
painless papules and pustules that ulcerate near genital areas
condylomata lata; syphilis
painful small soft papules that become ulcers with ragged edges and coalesce
chancroid; H. ducreyi
painless small transient nonindurated lesion that ulcerates and heals quickly leaving scar
lymphogranuloma venereum; C. trachomatis
painless red nodule develops into elevated granulomatous mass
granuloma inguinale; donovania granulomatis, calymmatobacterium granulomatis
painful vesicles on skin or mucous membranes that become ulcers with red areola
genital herpes; HSV
painless soft moist redish swellings that grow rapidly into pedunculated masses with califlower appearance
genital warts
condylomata acuminata
papilloma virus
painful genital lesions
genital herpes
painless genital lessions
condylomata lata
lymphogranuloma venereum
granuloma inguinale
condylomata acuminata
cystitis etiology
infection of bladder by E. coli, proteus, klebsiella
predisposed by urinary stasis, tumors, stones, strictures, prostatic hypertrophy, neurogenic bladder, sexual intercourse
cystitis presentation
dysuria, frequency, urgency and suprapubic (but not flank) tenderness
may also have hematuria, low fever
cystitis diagnosis and treatment
screening test is urinalysis looking for WBCs, RBCs, protein or bacteria
nitrites indicate gram- bacteria
urine culture with >100,000 colonies per mL of urine is confirmation
treat with 3 days of TMP/SMX or any quinolone (not pregnancy)
7 days for diabetics
acute bacterial pyelonephritis etiology
ascension of E. coli, klebsiella, proteus
predisposed by female sex, obstruction due to strictures, tumors, calculi, prostatic hypertrophy, neurogenic bladder, vesicouretheral reflux, catheter; catherterized immunocompromised patients are predisposed to candida
acute bacterial pyelonephritis presentation
fever, chills
frequeny, dysuria
flank pain, costovertebral angle tenderness
acute bacterial pyelonephritis diagnosis
clinical diagnosis with confirmation by clean-catch urinalysis and culture >100,000 bacteria/mL
if patient does not improve in 3 days or complications are suspected --> ultrasound or CT is indicated
acute bacterial pyelonephritis treatment
10-14 days with fluoroquinolone OR
ampicillin + gentamycin OR
third-gen ceph
if can't tolerate medication --> hospitalization
perinephric abscess etiology
abscess from kidney cortex to surrounding areas due to E. coli, klebsiella, proteus
predisposed by kidney stones (20-60%)
prostatic hypertrophy
neurogenic bladder
perinephric abscess presentation
insidious onset (2-3 weeks) of fever, flank pain, palpable flank mass, abdominal pain, and persistence of symptoms after pyelonephritis treatment
perinephric abscess diagnosis and treatment
urinalysis and culture of urine
then ultrasound and aspiration of abscess for definitive etiology and sensitivity
quinolone, ampicillin/gentamycin, third-gen ceph
drainage is necessary
impetigo etiology
superficial pustular infection with due mainly to staph aureus and group A strep
impetigo presentation
maculopapules that progress to vesicles, pustules and bullae with golden crusts
can lead to lymphangitis, furunculosis or cellulitis
more common on limbs and face, may follow trauma to skin
impetigo diagnosis and treatment
clinical diagnosis
treat with first-gen ceph OR oxacillin, cloxacillin, dicloxacillin
can also use topical mupirocin or bacitracin in mild cases
if allergic use macrolides
superficial cellulitis due to group A strep
tender, demarcated, shiny red, indurated, edematous lesions on limbs or face
treat with semisynthetic penicillin or first-gen ceph if undistinguishable with cellulits, else penicillin for Group A strep
tinea etiology
dermatophytes: microsporum, trichophyton, epidermophyton
tinea presentation
corporis: papulosquamous lesions with riased border in the body; pedis: macerated and scaling borders; unguium: thickened nails; capitis: small scaly semibold graysish patched on head; cruris: ringed lesions on crural folds and inner thighs; barbae: on face
tinea diagnosis and treatment
potassium hydroxide preparation; culture as definitive test; treat with terbinafine or itraconazole orally for capitis, corporis and unguium; topical clotrimazole/ketoconazole for cruris, pedis and mild corporis
candidiasis etiology
candida infection more frequently in:
systemic antibacterial therapy
corticosteroid or antimetabolites
blood dyscrasias
intertriginous candidiasis presentation
intertriginous: well-demarcated, erythematous, itchy, exudative patches rimmed with red small pustules; in groin, gluteal folds (diper rash), axilla, umbillicus, inframmary areas
vulvovaginitis presentation
candidiasis with white or yelloish discharge with inflammation of the vaginal wall and vulva; common in pregnancy and diabetes
oral candidiasis
also known as thrush; white patches of exudates on tongue or bucal mucosa
candidal paronychia
painful red swelling around the nail
candidiasis diagnosis and treatment
potassium chloride on slide, culture is definitive
treat with topical nystatin or azoles
if serious infection or paronychia use amphotericin and fluconazole
tinea versicolor
pityrosporum orbiculare (malassezia furfur) leads to tan/brownish scaling macules that coalesce on neck, face and abdomen; diagnose with KOH showing spaghetti and meatballs; treat with topical selenium sulfide or azoles
due to itch mite or sarcoptes scabiei; pruritus, burrows and papules on skin folds; immunocompromised and Down patients can have malodorous discharge; diagnose by showing parasites in scrapings with mienral oil; treat with permethrin, lindane or ivermectin
due to pediculus humanus capitis, pediculus humanus corporis, phthirus pubis; itching, excoriations, erythematous macules and papules may have secondary bacterial infection; diagnose with direct analysis of hair-bearing surfaces; treat with permethrin, lindane
molluscum contagiosum
small waxy papules with central umbilication due to poxvirus
specially in children and HIV
clinical diagnosis
treat by cryotherapy, curettage, electrocautery
osteomyelitis etiology
most common organism is staph

acute hematogenous: in children occurs mostly in metaphysis of tibia and femur, in adults in the vertebral bodies

secondary to contiguous infection: recent trauma or prosthetic (could be polymicrobial)

vascular insufficiency: diabetics over 50, small bones of lower limb and majority are polymicrobial
osteomyelitis presentation
pain, erythema, swelling and tenderness over affected bone; in vascular insuf. May have ulcer; sometimes also drainning tract
osteomyelitis diagnosis
plain x-ray is usually first test but takes at least 2 weeks to show periosteal elevation
technetium scan and MRI detect it much earlier
a normal ESR strongly excludes osteomyelitis
bone biopsy and culture is best diagnostic test and its needed
osteomyelitis treatment
empiric: semisynthetic penicillin or vancomycin + aminoglycoside or third-gen ceph
then specific treatment
total is 6-12 weeks
adults also need drainage and debridment
septic arthritis etiology
joint infection mostly by gonococcus but also by gram+ (85%, staph 60%)
other gram- (10-15%) or polymicrobial (5%)
main risk factor for gonococcal is sexual activity
nongonococcal is mostly hematogenous spread by bites, direct inoculation by surgery or trauma, RA, OA, prothesis, gout, sickle cell, IV drug use, diabetes, HIV
septic arthritis presentation
gonococcal: polyarticular (50%) swollen, tender, erythematous joint with decreased range of motion also with tenosynovitis, migratory polyarthralgia, and petechiae or purpura

non-gonococcal is mostly monoarticular and doesn't have systemic involvement
septic arthritis management
joint aspiration along with empiric nafcillin combined with aminoglycoside or third-gen ceph
for gonococcal: ceftriaxone
gas gangrene etiology
80% C. perfringens associated with trauma, war and motor vehicle accidents; the wound must be deep, necrotic and without exit to surface
gas gangrene presentation
pain, swelling and edema 1-4 days after incubation
later hypotension, tachycardia, fever, crepitation and renal failure
gas gangrene diagnosis
gram+ rods on stain without white cells, culture and gas bubble on x-ray are suggestive
direct visualization of pale, dead muscle with sweet-smelling discharge is definitive diagnosis
gas gangrene management
24 million units of penicillin/day or clindamycin if allergic + debridment or amputation
hyperbaric oxygen might be of benefit
infective endocarditis predisposing factors
dental procedures
oral and upper respiratory surgery
some GI procedures
GU surgery
prosthetic heart valves
valvular heart disease
catheters to heart
IV drug abuse
top 5 organisms of endocarditis in native valves
strep viridans (50-60%)
staph aureus (20-30%)
other strep (15-20%
enterococci (5-15%)
staph epidermidis (1-3%)
top 3 organisms of endocarditis in narcotic addicts
staph aureus (60-95%), streptococci (10-20%), staph epidermidis (5-10%)
top 3 organisms of endocarditis in prosthetic valves
staph epidermidis (40-50%, 10-20 days later)
staph aureus (15-20%, 40-60 days later)
strep viridans (5-20%, 20-30 days later)
acute endocarditis etiology
bactermia with staph aureus seeds previously healthy valves and produces large vegetations, fever, spesis, splenomegaly
subacute endocarditis etiology
strep viridans is most common
low virulence seeding of abnormal valves with small vegetations made of fibrin, platelets, debris and bacteria
infective endocarditis presentation
fever + new heart murmur + anemia
chills, sweats, weakness, dyspnea, anorexia, cough, embolic events (petechiae, splinter hemorrhages, Janeway lesions), skin manifestation, splenomegaly, FROM JANE
infective endocarditis major diagnostic criteria
positive blood culture and abnormal echo; need both or 1 major/3minor for diagnosis
infective endocarditis minor criteria
cardiac lesion from IV drug use
vascular events (arterial emboli, septic lung infarcts, Janeway)
immunologic events (Osler, Roth, GN, rheumatoid factor)
microbiologic evidence (active infection consistent with endocarditis)
need 3 minor and 1 major or 2 major for diagnosis
infective endocarditis empiric treatment
antistaph (nafcillin) + antistrep (penicillin/ampicillin) + gentamicin
change as soon as specific agent is known by blood culture
infective endocarditis specific treatment for strep viridans
4 weeks penicillin OR if allergic, 4 weeks of ceftriaxone or vancomycin OR 2 weeks of penicillin or ceftriaxone + gentamicin
infective endocarditis specific treatment for native valve/staph aureus
if methicillin sensitive:
4-6 weeks of nafcillin + 5 days gentamicin
OR cefazolin or vancomycin + 5 days of gentamicin if allergic

for methicillin resistant:
4-6 weeks of vancomycin
infective endocarditis specific treatment for enterococcus
4-6 weeks of penicillin/ampicillin + gentamicin OR vacomycin + gentamicin
major criteria for infective endocarditis surgery
progressive or unresponsive CHF
recurrent systemic emboli
persistent bacteremia despite antibiotics
fungal etiology
extravalvular infection
prosthetic valve dehiscence or obstruction
recurrence despite therapy
minor criteria for infective endocarditis surgery
resolved CHF with therapy
single systemic embolic event
large aortic or mitral vegetations on echo
prosthetic valve infection other than penicillin sensitive strep
gram- tricuspid endocarditis
persistent fever
new regurgitation
indications of prophylaxis for infective endocarditis
when there's serious cardiac defect and procedure causing bacteremia; for dental procedures give amoxicillin or clindamycin/macrolide if allergic
cardiac conditions that indicate infective endocarditis prophylaxis
prosthetic heart valves
previous bacterial endocarditis
most congenital cardiac malformations
conditions that don’t require infective endocarditis prophylaxis
surgically corrected systemic pulmonary shunts, rheumatic valve dysfunction, hypertrophy cardiomyopathy, mitral valve prolapse with regurgitation, surgical repaired intracardiac defects
acute pericarditis etiology
any infectious agent
coxsackie and ECHO viruses are most common viruses
vascular --> SLE, RA, scleroderma
1/3 of uremic patients
neoplasia adjacent to heart
mediastinal irradiation
rheumatic fever
injury to heart
acute pericarditis presentation
sharp pleuritic chest pain improved by leaning forward; friction rub heard at apex; low fever
pericardial tamponade presentation
signs and symptoms of perdicarditis plus pulsus paradoxus, distended neck veins, tachycardia, hypotension
acute pericarditis diagnosis
diffuse ST elevation and maybe PR depression
echo normal in viral but used to detect effusion
pericardiocentesis for microbiology
acute pericarditis therapy
treat underlying cause; if viral give indomethacin or ibuprofen or prednisone if no response or if TB; pericardiocentesis for large effusions
myocarditis etiology
any infectious agent but coxackie B is very common
also radiotherapy, drugs, vascular disease, hyperthyroidism
myocarditis presentation
asymptomatic or any presentation
signs of myocardial dysfunction (dyspnea, fatigue) or rapid progression to chest pain and arrhythmia
may have S3 and murmurs
myocarditis diagnosis
any EKG alteration like ST-T wave changes, heart blocks
elevated cardiac enzymes may be found
may have left ventricular systolic dysfunction on echo
viruses may be isolated from body fluids or titers of serum antibodies are found
myocarditis treatment
supportive for viral (resolves spontaneously); steroids can be damaging
Lyme disease presentation
80% develop erythema migrans rash 3-30 days after bite
flulike illness occurs in 50%
neurologic symptoms develop weeks later in 10-20%
(facial paralysis, meningitis, encephalitis or headaches)
heart block, arrhythmia, myocarditis or pericarditis in <10%
migratory polyarthritis develops months to years later in 60%;
Lyme disease diagnosis
diagnostic criteria are presence of rash with at least one late manifestation + ELISA and western blot looking for anti borrelia antibodies (serum studies may not false negative early when rash is still present)
Lyme disease treatment
rash, facial palsy and joint pain with doxycyline
if serious neurologic or cardiac --> IV ceftriaxone
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