Infectious Disease Flashcards
In which 3 settings would you treat asymptomatic bacteruria?
- Pregnancy
- Prior to urologic procedure
- In the first few months after kidney transplant to prevent rejection
What is the standard treatment for uncomplicated cystitis, complicated cystitis, uncomplicated pyelonephritis, and complicated pyelonephritis?
Uncomplicated cystitis: 3 days, urine culture not required
Complicated cystitis: 7 days (includes all males)
Uncomplicated pyelonephritis: 7 days
Complicated pyelonephritis: 7-10 days
Otitis externa is usually due to what organisms?
Pseudomonas is the most common cause of otitis externa with Staph aureus a distant second.
How many days of symptoms are required to diagnose a patient with bacterial sinusitis and prescribe antibiotics? What are the usual causative organisms?
Bacterial sinusitis should be considered when symptoms last >10 days. Usual organisms include Strep pneumo, Hemophilus influenzae, and Moraxella catarrhalis
What are some symptoms of rhinocerebral mucormycosis?
Rhinocerebral mucormycosis may present with unilateral or bilateral congestion, sinus pressure, and tissue necrosis with black eschar.
How can you differentiate allergic rhinitis from bacterial?
Bacterial sinusitis generally has thick, purulent drainage, sinus tenderness, and fevers.
Treat bacterial sinusitis with which antibiotics?
Augmentin or quinolones are the treatments of choice for bacterial sinusitis.
What is the treatment for rhinocerebral mucormycosis?
Rhinocerebral mucormycosis is treated with amphotericin B and aggressive surgical debridement.
What clinical findings are seen with group A beta-hemolytic streptococcal pharyngitis?
Think Centor criteria: exudative pharyngitis, fever, tender cervical adenopathy, and lack of cough.
What is the clinical presentation of M. marinum?
M. marinum presents with nonhealing skin ulcers in people who work with fish tanks. Lesions may spread along lymphatic channels. Lesions also tend to be on distal extremities because the organism does not grow well at body temperature.
How is prosthetic joint infection diagnosed?
Prosthetic joint infection may be seen as widening of the bone-cement interface. MRI and bone scan are not helpful because of high false positive rate. Joint aspiration is the diagnostic test of choice.
Which organism causes osteomyelitis in a patient with sickle cell anemia (besides S. aureus)?
Salmonella causes osteomyelitis in sickle cell patients.
What is the time of onset of vomiting due to B. cereus toxin ingestion?
B. cereus toxin presents with nausea/vomiting in 1-6 hours after ingestion and diarrhea in 8-16 hours after ingestion. It grows best in starchy foods, so think of this in someone
who becomes ill after eating rice.
Which finding on stool evaluation suggests invasive diarrhea?
The presence of fecal leukocytes or lactoferrin suggests an invasive diarrhea.
Know the recommendations for prophylaxis and treatment of traveler’s diarrhea?
Travelers should be educated about ways to prevent travelers’ diarrhea. Prophylactic antibiotics should be given to those who are immunosuppressed or have cardiac, renal, or inflammatory bowel disease. Treatment for travelers’ diarrhea includes ciprofloxacin, azithromycin, or rifaximin. 1-3 days of treatment is adequate. Anti-diarrheals should be used only after antibiotics are started.
Salmonella infection is spread by which animals?
Salmonella is present in many animals and can be spread by frozen foods (chicken), milk, or eggs. Baby chicks, turtles, and other exotic pets can also be a source of infection.
What is a possible adverse consequence of treating infectious diarrhea due to E. coli O157:H7 with antibiotics?
Antibiotic treatment of E. coli O157:H7 increases risk of HUS by killing organisms and causing release of more toxin.
What is the empiric treatment for Shigella infection?
Shigella should be treated with a fluoroquinolone until susceptibility testing is available.
How is noninvasive Yersinia infection treated?
Noninvasive Yersinia infection is generally treated supportively. For invasive disease antibiotics are used including 3rd generation cephalosporins, TMP/SMX, and
tetracyclines.
Vibrio vulnificus can cause severe disease in which groups of patients?
Vibrio vulnificus causes severe disease in the immunocompromised and liver disease patients.
What is the current treatment of choice for patients with severe C. diff diarrhea?
Oral vancomycin is the treatment of choice for severe C. diff diarrhea. Severe C. diff is defined by WBC >15,000 or increase in creatinine by 50%.
What is the recommendation for treatment of first recurrence of C. difficile?
First recurrence of C. diff is treated by repeating the same antibiotic.
Which infection control precautions must be used on patients with C. diff diarrhea?
Hand washing (not gels) and contact isolation are used to prevent spread of C. diff.
What is the empiric treatment for bacterial liver abscesses?
Liver abscesses are often due to mixed fecal flora (with GNRs, enterococci, and anaerobes) so tailor empiric antibiotics accordingly. Treatment should include drainage and antibiotics guided by culture of drained fluid.
To which 3 groups of patients should you give antibiotic prophylaxis of primary peritonitis?
- ascitic fluid protein <1.0 g/dl
- variceal bleed
- prior episode of primary peritonitis
How do you screen for gonorrhea? For Chlamydia? For syphilis?
Populations at increased risk for STIs include: 15-24 years of age, African American, new partner in last 2 months, multiple partners, history of previous STIs, drug use, recent
exposure to jail or detention facility, finding sex partners from the internet, contact with prostitutes, and men who have sex with men. Screen for gonorrhea and Chlamydia with NAAT of vaginal swabs. Since almost all men are symptomatic, there are no screening recommendations for men. Sexually active women <25 years of age should be screened annually as should older women if they are in a high risk group. Screen for syphilis in all general risk groups and during pregnancy.
Characterize the ulceration caused by syphilis.
Syphilis presents with painless ulcer 3-40 days after exposure.
In which stages of syphilis can stroke occur?
Stroke can present in secondary and tertiary syphilis.
When referring to neurosyphilis, what does PARESIS stand for?
P = defects in personality A = reduced affect R = abnormal reflexes E = eyes (Argyll-Robertson pupil) S = defects in sensorium I = defects in intellect S = defects in speech
Can a patient have negative RPR and have neurosyphilis?
⅓ of patients with tertiary syphilis have a negative RPR because the IgM response has “burnt out”.
When does an MHA-TP revert to negative after a patient has syphilis?
Treponemal tests for syphilis turn positive in 2-4 weeks and remain positive for life.
List the treatment regimens for various stages of syphilis.
Primary, secondary, and early latent syphilis: benzathine PCN G 2.4MU IM x 1
Late latent, latent of unknown duration, and nonneurologic tertiary: benzathine PCN G 2.4MU IM every week x 3
Neurosyphilis: PCN G 18-24 MU IV divided every 4 hours or by continuous infusion x 10-14 days
What drug is used to treat syphilis in pregnancy? What if a woman has an anaphylactic PCN allergy?
PCN is the treatment of choice in pregnant women. If a woman is allergic to PCN, she should be desensitized.
Characterize the ulceration caused by chanchroid.
The ulcer of chancroid evolves from a papule to a pustule to a ragged ulcer, all of which are painful.
Discuss the clinical manifestations of LGV and granuloma inguinale.
Both LGV and granuloma inguinale present with painless ulcers followed by inguinal adenopathy (groove sign) in LGV and inguinal granulomas that look like lymph nodes in granuloma inguinale.
True or false? Pregnant women with PID rarely need hospitalization.
All pregnant patients with PID should be admitted for treatment.
Know the inpatient and outpatient regimens for treatment of PID.
Inpatient: cefoxitin or cefotetan IV plus doxycycline PO or IV or clindamycin and gentamicin IV
Outpatient: Ceftriaxone IM x 1 then doxycycline x 14 days +/- metronidazole x 14 daysor cefoxitin IM x1 plus probenecid plus doxycycline x 14 days +/- metronidazole
x 14 days
What is the typical presentation of disseminated gonorrhea?
Disseminated gonorrhea presents with a sparse pustular rash (<10 lesions) and septic arthritis, commonly with tenosynovitis.
What is the best way to diagnose disseminated gonorrhea?
Gram stain and culture of skin lesions have a very low yield (15%) but specimens taken from genital sources have an 85% yield.
Which 3 tests are useful to determine the etiology of vaginitis? In what way?
Vaginal pH, wet prep and KOH prep determine the etiology of vaginitis. pH is >5.0 in bacterial vaginosis and trichomonas. Wet prep shows clue cells in BV. KOH releases a fishy odor in BV and trichomonas (sniff test) and fungal elements in candida.
For which infection should you test women with recurrent or recalcitrant candidal vulvovaginitis? For which metabolic disease?
Women with recurrent or recalcitrant candidal vulvovaginitis should be tested for both HIV and diabetes.
Which organism is the most common cause of bacterial meningitis in adults?
Strep pneumoniae is the most common cause of bacterial meningitis in all adult age ranges.
What is the clinical presentation of bacterial meningitis?
Bacterial meningitis presents with fever, headache, and stiff neck.
What is the standard empiric treatment for bacterial meningitis in adults <50 years of age?
Initiate empiric treatment for bacterial meningitis with ceftriaxone and vancomycin.
To which contacts should you give prophylaxis for meningococcal meningitis?
Meningococcal prophylaxis should be given to those with close contact for >8 hours and to those exposed to oral secretions (such as healthcare workers who intubate a patient with meningococcal meningitis.
Which lab results are consistent with viral meningitis?
CSF WBC < 1000, normal glucose, and protein < 100mg/dl.
Name the infectious diseases that can cause Bell’s palsy.
Bell’s palsy can be caused by HSV and Lyme disease.
Empiric coverage for a patient with a spinal epidural abscess should cover which organism, specifically?
Empiric treatment for spinal epidural abscess needs to include Staph aureus.
What are acceptable empiric regimens for a brain abscess?
PCN or 3rd generation cephalosporin plus metronidazole. Add staph coverage if neurosurgical procedure or history of bacteremia/endocarditis. Also think Pseudomonas
in neurosurgical patients.
Name some animals that are high risk for transmission of rabies.
Bats, foxes, skunks, raccoons, dogs, cats, and ferrets all transmit rabies. Rats, squirrels, and other rodents do not. In US the leading cause is bats. Worldwide the leading cause is dogs.
What side of the heart is more prone to developing native valve endocarditis?
The left side of the heart is more prone to native valve endocarditis.
What is the usual cause of prosthetic valve endocarditis in the 1st year after surgery?
S. epidermidis is the usual cause of prosthetic valve endocarditis in the 1st year after surgery.
What are some specific physical exam signs of endocarditis?
Splinter hemorrhages, Janeway lesions, Osler nodes, and Roth spots are some specific but not sensitive signs in endocarditis.
How many sets of blood cultures should be drawn on the patient with suspected endocarditis?
3 sets of blood cultures should be drawn over 8 hours from various sites in a patient withsuspected endocarditis.
Which organisms cause culture-negative endocarditis?
Culture-negative endocarditis may be caused by fungi, Coxiella burnetti, Tropheryma whipplei, Bartonella species, Legionella species, Chlamydia psittaci, or Abiotrophia
(previously nutritionally deficient streptococcus).
What 2 types of tests make up the major criteria for the diagnosis of endocarditis?
Blood cultures and echocardiography make up the major criteria for diagnosis of endocarditis. Coxiella burnetti is the only cause of endocarditis that can be diagnosed
with a single positive culture.
Review and commit to memory the modified Duke criteria. What is required for the definite diagnosis of endocarditis?
Definite endocarditis can be diagnosed with: pathologic evidence of infection 2 major criteria 1 major and 3 minor criteria 5 minor criteria
Minor criteria include:
predisposing condition (valve disease or IV drug use)
fever > 100.4 F (38.0 C)
vascular phenomena (Janeway, arterial emboli, mycotic aneurysm, stroke)
immunologic phenomena (GN, Osler nodes, Roth spots, +RF)
Positive blood cultures that do not meet major criteria
Know the various treatment regimens to treat endocarditis based on resistance patterns and type of valve (native vs. prosthetic).
Strep viridans or Strep bovis - PCN G or ceftriaxone
MSSA - nafcillin
MRSA or coag-negative staph - vancomycin
Staph, uncomplicated right-sided - nafcillin plus gentamicin or daptomycin
Enterococci - PCN G or ampicillin or vancomycin + gentamicin
AACEK - ceftriaxone
List the indications for early surgical treatment of bacterial endocarditis.
Surgery is indicated in bacterial endocarditis if the following are present:
- heart failure refractory to medical therapy
- resistant organisms with no available bactericidal therapy
- development of heart block
- development of an abscess
- persistent positive blood cultures 7 days into therapy
- a relapse of prosthetic valve endocarditis
- new embolic lesion on therapy
Patients with HIV/AIDS are at risk for developing infections with which organisms?
Patients with HIV/AIDS are at risk for infections occurring from impaired cell-mediated immunity (ie. PCP, viruses, mycobacteria, and fungi) as well as those seen with impaired humoral immunity (ie. pneumococcus, meningococcus, and Giardia).
How is HIV infection diagnosed in the acute and chronic stages? What is the utility of measuring HIV RNA?
In acute infection HIV RNA is positive after ~5 days. Diagnosis of chronic HIV is done through 4th generation test for antibodies to HIV-1 and HIV-2 as well as p24 antigen. HIV RNA is useful for initial diagnosis, to assess prognosis, and to monitor response to antiretroviral therapy.
What is the viral setpoint, and what is its significance?
The viral setpoint is the viral load that is established after the immune system has controlled the primary infection. This differs in different patients. When a patient stops
ART the viral load quickly rebounds to this baseline setpoint.
What is the significance of the CD4 count?
CD4 count determines level of immunocompromise and can be used to judge which opportunistic infections the patient is susceptible to.
Which new HIV+ patients should receive resistance testing?
All newly diagnosed patients with HIV should undergo testing for resistance.
What is the serious side effect of abacavir?
Abacavir hypersensitivity syndrome is a potentially life-threatening complication of abacavir therapy.
What are the side effect of ZDV? ddI?
Zidovudine can cause marrow suppression and myopathy. ddI can cause pancreatitis and neuropathy.
Which NRTI can cause the development of kidney disease?
Tenofovir can cause kidney injury.
Which antiretroviral is teratogenic?
Efavirenz is teratogenic.
What is the primary toxicity of nevirapine?
Nevirapine can cause hepatotoxicity and rash.
Hyperbilirubinemia can occur with which antiretroviral drug?
Atazanavir can cause jaundice.
Which PI is used to boost the drug concentrations of other PIs?
Ritonavir is used to boost concentrations of other protease inhibitors.
Which exposures should receive PEP for HIV?
Contact of bloody fluids from an HIV+ patient with non-intact skin or mucous membranes should prompt post-exposure prophylaxis.
Which pregnant women should be treated for HIV? With what? What is the treatment goal?
All pregnant women should be treated for HIV with a goal of making the viral load undetectable. This will decrease the risk of vertical transmission from 25% to <1%. Any
agent can be used except efavirenz which is teratogenic. Additionally, all women with viral load >1000 at time of delivery should receive IV zidovudine, and the baby should be delivered by C-section.
