Infectious Disease Flashcards
1
Q
In which 3 settings would you treat asymptomatic bacteruria?
A
- Pregnancy
- Prior to urologic procedure
- In the first few months after kidney transplant to prevent rejection
2
Q
What is the standard treatment for uncomplicated cystitis, complicated cystitis, uncomplicated pyelonephritis, and complicated pyelonephritis?
A
Uncomplicated cystitis: 3 days, urine culture not required
Complicated cystitis: 7 days (includes all males)
Uncomplicated pyelonephritis: 7 days
Complicated pyelonephritis: 7-10 days
3
Q
Otitis externa is usually due to what organisms?
A
Pseudomonas is the most common cause of otitis externa with Staph aureus a distant second.
4
Q
How many days of symptoms are required to diagnose a patient with bacterial sinusitis and prescribe antibiotics? What are the usual causative organisms?
A
Bacterial sinusitis should be considered when symptoms last >10 days. Usual organisms include Strep pneumo, Hemophilus influenzae, and Moraxella catarrhalis
5
Q
What are some symptoms of rhinocerebral mucormycosis?
A
Rhinocerebral mucormycosis may present with unilateral or bilateral congestion, sinus pressure, and tissue necrosis with black eschar.
6
Q
How can you differentiate allergic rhinitis from bacterial?
A
Bacterial sinusitis generally has thick, purulent drainage, sinus tenderness, and fevers.
7
Q
Treat bacterial sinusitis with which antibiotics?
A
Augmentin or quinolones are the treatments of choice for bacterial sinusitis.
8
Q
What is the treatment for rhinocerebral mucormycosis?
A
Rhinocerebral mucormycosis is treated with amphotericin B and aggressive surgical debridement.
9
Q
What clinical findings are seen with group A beta-hemolytic streptococcal pharyngitis?
A
Think Centor criteria: exudative pharyngitis, fever, tender cervical adenopathy, and lack of cough.
10
Q
What is the clinical presentation of M. marinum?
A
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.
11
Q
How is prosthetic joint infection diagnosed?
A
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.
12
Q
Which organism causes osteomyelitis in a patient with sickle cell anemia (besides S. aureus)?
A
Salmonella causes osteomyelitis in sickle cell patients.
13
Q
What is the time of onset of vomiting due to B. cereus toxin ingestion?
A
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.
14
Q
Which finding on stool evaluation suggests invasive diarrhea?
A
The presence of fecal leukocytes or lactoferrin suggests an invasive diarrhea.
15
Q
Know the recommendations for prophylaxis and treatment of traveler’s diarrhea?
A
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.
16
Q
Salmonella infection is spread by which animals?
A
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.
17
Q
What is a possible adverse consequence of treating infectious diarrhea due to E. coli O157:H7 with antibiotics?
A
Antibiotic treatment of E. coli O157:H7 increases risk of HUS by killing organisms and causing release of more toxin.
18
Q
What is the empiric treatment for Shigella infection?
A
Shigella should be treated with a fluoroquinolone until susceptibility testing is available.
19
Q
How is noninvasive Yersinia infection treated?
A
Noninvasive Yersinia infection is generally treated supportively. For invasive disease antibiotics are used including 3rd generation cephalosporins, TMP/SMX, and
tetracyclines.
20
Q
Vibrio vulnificus can cause severe disease in which groups of patients?
A
Vibrio vulnificus causes severe disease in the immunocompromised and liver disease patients.
21
Q
What is the current treatment of choice for patients with severe C. diff diarrhea?
A
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%.
22
Q
What is the recommendation for treatment of first recurrence of C. difficile?
A
First recurrence of C. diff is treated by repeating the same antibiotic.
23
Q
Which infection control precautions must be used on patients with C. diff diarrhea?
A
Hand washing (not gels) and contact isolation are used to prevent spread of C. diff.
24
Q
What is the empiric treatment for bacterial liver abscesses?
A
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.
25
To which 3 groups of patients should you give antibiotic prophylaxis of primary peritonitis?
1. ascitic fluid protein <1.0 g/dl
2. variceal bleed
3. prior episode of primary peritonitis
26
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.
27
Characterize the ulceration caused by syphilis.
Syphilis presents with painless ulcer 3-40 days after exposure.
28
In which stages of syphilis can stroke occur?
Stroke can present in secondary and tertiary syphilis.
29
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
```
30
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”.
31
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.
32
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
33
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.
34
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.
35
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.
36
True or false? Pregnant women with PID rarely need hospitalization.
All pregnant patients with PID should be admitted for treatment.
37
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
38
What is the typical presentation of disseminated gonorrhea?
Disseminated gonorrhea presents with a sparse pustular rash (<10 lesions) and septic arthritis, commonly with tenosynovitis.
39
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.
40
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.
41
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.
42
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.
43
What is the clinical presentation of bacterial meningitis?
Bacterial meningitis presents with fever, headache, and stiff neck.
44
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.
45
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.
46
Which lab results are consistent with viral meningitis?
CSF WBC < 1000, normal glucose, and protein < 100mg/dl.
47
Name the infectious diseases that can cause Bell’s palsy.
Bell’s palsy can be caused by HSV and Lyme disease.
48
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.
49
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.
50
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.
51
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.
52
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.
53
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.
54
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.
55
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).
56
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.
57
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
58
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
59
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
60
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).
61
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.
62
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.
63
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.
64
Which new HIV+ patients should receive resistance testing?
All newly diagnosed patients with HIV should undergo testing for resistance.
65
What is the serious side effect of abacavir?
Abacavir hypersensitivity syndrome is a potentially life-threatening complication of abacavir therapy.
66
What are the side effect of ZDV? ddI?
Zidovudine can cause marrow suppression and myopathy. ddI can cause pancreatitis and neuropathy.
67
Which NRTI can cause the development of kidney disease?
Tenofovir can cause kidney injury.
68
Which antiretroviral is teratogenic?
Efavirenz is teratogenic.
69
What is the primary toxicity of nevirapine?
Nevirapine can cause hepatotoxicity and rash.
70
Hyperbilirubinemia can occur with which antiretroviral drug?
Atazanavir can cause jaundice.
71
Which PI is used to boost the drug concentrations of other PIs?
Ritonavir is used to boost concentrations of other protease inhibitors.
72
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.
73
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.
74
What are the symptoms of primary HIV infection?
Primary HIV infection presents with fever, lymphadenopathy, rash, pharyngitis, mucocutaneous ulcerations, myalgias/arthralgias, and aseptic meningitis.
75
Primary HIV infection sometimes resembles which illnesses?
Primary HIV infection resembles flu or mononucleosis.
76
Is PCP the most common pulmonary infection in the patient with HIV/AIDS?
Bacterial pneumonia is now the most common pulmonary infection in HIV.
77
What is the usual CD4 count in the patient with HIV/AIDS who develops PCP?
PCP usually develops in a patient with CD4 count <200.
78
How is PCP best diagnosed?
PCP is diagnosed by silver or immunostain of pulmonary secretions for sputum or BAL.
79
Which ancillary treatment should you give to patients who develop severe hypoxemia due to PCP?
PCP patients with severe hypoxemia (pO2 <60) should receive steroids.
80
When should you give patients primary prophylaxis for PCP?
Give primary prophylaxis for PCP to those with CD4 count <200.
81
What is the treatment duration for latent TB in patients with HIV/AIDS?
HIV patients with latent TB should receive INH for 9 months.
82
When should you give patients primary prophylaxis for MAC?
Primary prophylaxis for MAC should be given when CD4 count <50.
83
How is cryptococcal meningitis diagnosed?
Cryptococcal antigen in CSF is the diagnostic test of choice for cryptococcal meningitis.
84
What is the typical presentation of CNS toxoplasmosis?
Typical presenting symptoms of CNS toxoplasmosis include new onset seizures, neurologic deficit, and/or altered consciousness.
85
Which virus causes PML, and how does it present?
PML is caused by JC polyomavirus. Patients present with altered mental status, motor and sensory changes. Vision is especially affected given the long course of myelinated
nerves extending from the optic nerves to the occipital cortex.
86
Name some of the organisms that can cause chronic diarrhea in a patient with HIV/AIDS?
Chronic diarrhea in HIV/AIDS patients is often due to Cryptosporidium, microsporidia, Cyclospora, Cystoisospora, or bacterial pathogens (ie. Salmonella, Shigella, and Campylobacter).
87
Name some factors that affect whether a patient with neutropenia develops an infection.
Degree of neutropenia and duration of neutropenia are predictors of infection.
88
What are the options for empiric treatment of the febrile neutropenic? When is vancomycin included?
Treatment for febrile neutropenia should cover GNRs. One of the following should be used: Piperacillin/tazobactam, a carbapenem, or cefepime. Vancomycin should be added
if there is evidence of line/port infection, pneumonia, hypotension or severe sepsis, positive blood culture for Gram + organism, persistent fever on initial antibiotic, history of MRSA or known colonization.
89
In the empiric treatment of febrile neutropenia, when would you choose voriconazole over an echinocandin?
Voriconazole should be chosen over an echinocandin in a febrile neutropenia patient who
has pulmonary infiltrates because it more predictably covers Aspergillus.
90
Differentiate the 3 types of nosocomial pneumonias.
Hospital-acquired pneumonia: starts >48 hours after admission
Ventilator-associated pneumonia: occurs >48-72 hours after intubation
Healthcare-associated pneumonia: patient who was hospitalized for >2 days in the past 90 days, has resided in SNF, received home infusion therapy, or family member
with infection from multi-drug resistant organism
91
Which organisms usually cause a CLABSI?
CLABSI is usually caused by S. aureus or S. epidermidis.
92
How do you confirm the diagnosis of a CLABSI?
The diagnosis of CLABSI is confirmed when culture of catheter tip and blood culture are same organism.
93
What is the clinical presentation of toxic shock syndrome?
TSS presents with sunburn like rash, hypotnesion, and fever.
94
How do blood culture results differ between staphylococcal and streptococcal toxic shock?
Blood cultures are usually positive with streptococcal TSS and negative with staphylococcal TSS.
95
What is the drug of choice for initial treatment of MRSA bacteremia (until MIC results are available)?
Vancomycin should be used to treat MRSA bacteremia until susceptibility testing is available.
96
Which antibiotics are useful to treat skin and soft tissue staphylococcal infections?
TMP/SMX and doxycycline are generally used to treat staphylococcal skin and soft tissue infections due to the high prevalence of MRSA.
97
When should you use 2 antibiotics to treat enterococcal infections? Which drugs would you choose?
Complicated bacteremia and endocarditis due to enterococcus should be treated with 2 antibiotics. Usual choices include PCN G, ampicillin, or vancomycin plus gentamicin.
98
Which patient populations are at risk for Listeria infections?
Populations at risk for Listeria include those with impaired cell-mediated immunity including the elderly, pregnant women, those with AIDS, leukemia, or lymphoma, and
those on immunosuppressive therapy.
99
Treatment of serious Listeria infections includes which drug?
Treatment of serious Listeria infections should include ampicillin.
100
What are the clinical manifestations of anthrax?
1) Cutaneous - painless ulceration which often forms black eschar
2) Inhalational - wool sorters, bioterrorism
3) Gastrointestinal and pharyngeal - from undercooked meat, pharyngeal and GI ulcers
101
Which important x-ray finding do you see with inhalational anthrax?
Look for widened mediastinum in patients with inhalational anthrax. This may present with flu-like illness that rapidly deteriorates after day 2.
102
If a pathology report describes beaded, branching, mildly acid-fast, filamentous organisms, which organism is likely?
Nocardia are beaded, branching, mildly acid-fast, filamentous organisms.
103
When should you suspect Pseudomonas as a cause of infection?
Pseudomonas is a common cause of hospital acquired infection. It should also be considered in puncture wounds of feet through shoes, otitis externa, ecthyma
gangrenosum, and hot tub folliculitis.
104
Which form of plague is transmitted person-to-person?
Pneumonic plague caused by Yersinia pestis can be spread person-to-person. It can present like tularemia, but tularemia does not exhibit person-to-person spread.
105
Which associated symptoms are often observed with Legionella pneumonia?
Legionella pneumonia is associated with diarrhea, hyponatremia, hypophosphatemia, and CNS effects.
106
Which geographic locations have the most causes of tularemia?
Tularemia is most prevalent in Arkansas, Missouri, and Oklahoma.
107
What are the manifestations of bartonellosis?
Bartonella causes cat-scratch fever which presents with a skin lesion at site of inoculum and then tender lymphadenopathy. In immunocompromised patients it can cause bacillary angiomatosis.
108
Name the clinical signs and symptoms of RMSF. Which drugs are used for treatment?
RMSF presents with rash starting in the distal extremities, fever, severe headache, and arthralgias. RMSF is treated with doxycycline or chloramphenicol.
109
What is Q fever? How is it treated?
Q fever presents with flu-like illness with or without pneumonia and/or hepatitis. 5% of infections become chronic and manifest as FUO or culture-negative endocarditis. It is a zoonosis transmitted by aerosol released from infected animal. It is seen in
slaughterhouse workers and those exposed to animal products of conception during birthing. It is diagnosed by serologies. It is treated with doxycycline.
110
How do HME and HGA present? How are they diagnosed?
Patients with HME and HGA present with fever and severe headache. They may also have thrombocytopenia, leukopenia, or pancytopenia. >30% of patients with HME have rash, but rash is rare in HGA. It is diagnosed by the presence of morulae in WBCs. A 4-fold rise in serologies is also diagnostic.
111
How does M. marinum infection present?
M. marinum presents with a nonhealing ulcer in patients working with fish tanks. It can then spread along lymphatic channels. Similar lymphocutaneous disease can be seen in Nocardia and Sporotrichosis.
112
Which associated symptoms are often seen in respiratory infections due to C. pneumoniae?
Bronchospasm, early pharyngitis, and hoarseness are often seen with respiratory infections due to C. pneumoniae.
113
Which spirochetal disease that causes jaundice and meningitis most often affects veterinary workers and people who engage in outdoor water sports?
Leptospirosis is a spirochete infection transmitted by contact with infected animals or contaminated water. It is common in Hawaii (~50% of U.S. cases).
114
What are the clinical presentations of leptospirosis?
Leptospirosis presents with a wide range of signs and symptoms ranging from myalgias, fevers, and headache (with or without aseptic meningitis) to Weil syndrome (severe hepatitis with renal failure, pneumonitis, and hemorrhagic complications). Conjunctival suffusion is highly specific.
115
Which symptoms manifest in the various stages of Lyme disease?
Stage 1 - early localized with erythema migrans, arthralgias, fever, headache, and lymphadenopathy.
Stage 2 - early disseminated with neurologic symptoms (meningitis and cranial or peripheral neuritis) and heart infection.
Stage 3 - late with mono- or oligoarticular arthritis
116
What is the treatment for Lyme disease with symptomatic heart block?
Lyme disease with symptomatic heartblock is treated with IV ceftriaxone or IV PCN G times 14-21 days.
117
In a febrile patient who is receiving intravenous hyperalimentation, which blood stream infections might you expect?
Candidemia may arise in a patient receiving IV hyperalimentation.
118
When can you disregard Candida as a blood culture contaminant?
Candida in a blood culture should never be considered a contaminant.
119
What is the treatment of candidemia when a line is present?
Candidemia is a patient with a line requires removal of the catheter and systemic antifungal therapy. Initial therapy should be with an echinocandin until sensitivities are
known.
120
Which patient population develops hepatosplenic candidiasis?
Hepatosplenic candidiasis generally presents in a leukemic patient who is recovering from neutropenia.
121
Patients with candidemia should have what kind of referral?
Candidemia should prompt referral to an ophthalmologist.
122
Why are lipid amphotericin preparations not recommended for patients with funguria?
Amphotericin does not penetrate the urine so is not recommended for funguria.
123
Cryptococcal meningitis results in which LP abnormality?
Cryptococcal meningitis typically results in a high CSF opening pressure (>200mm H2O)
124
Empiric treatment for cryptococcal meningitis includes which drugs?
Treatment of cryptococcal meningitis involves 3 stages:
1. induction with amphotericin plus flucytosine for 2 weeks
2. consolidation with fluconazole 400mg/day for >8 weeks
3. maintenance with fluconazole 200mg/day for >1 year
125
Where is Coccidioides immitis found?
Coccidioides immitis is endemic to the southwest U.S. and northern Mexico.
126
What are the clinical presentations of histoplasmosis?
Most immunocompetent patients with histoplasmosis have a self-limited flu-like illness. It can also present with interstitial pneumonia, palate ulcers, and splenomegaly. It can cause upper lobe cavitary pneumonia resembling TB. It can disseminate in the immunocompromised population.
127
Which tests are best for diagnosing various presentations of histoplasmosis?
Urine and serum histoplasma antigen is best for diagnosis, although blastomycosis can cross-react with histoplasma antigen.
128
Severe histoplasmosis is treated with which antifungal?
Severe histoplasmosis requires amphotericin B followed by itraconazole.
129
What are the clinical manifestations of disseminated blastomycosis?
Disseminated blastomycosis presents with verrucous skin lesions with central ulceration. It can also have septic arthritis and osteomyelitis.
130
What patient groups are at risk for mucormycosis?
Diabetics, patients with prolonged neutropenia, and patients with hemochromatosis are at most risk for mucormycosis.
131
Tinea capitis requires treatment with which drug?
Tinea capitis requires oral antifungals such as terbinafine, itraconazole, or fluconazole.
132
How is serology useful in making a diagnosis of CNS toxoplasmosis?
IgG serology for toxoplasma is positive in CNS toxoplasmosis. Because this is a reactivation of infection, IgM is negative.
133
In a patient with diarrhea who has recently ingested imported fruits or vegetables, are protozoan parasites a likely cause of infection?
Cyclospora is the likely cause of diarrhea caused by imported fruits and vegetables.
134
Which form of malaria is caused by the banana-shaped gametocyte?
Plasmodium falciparum has banana-shaped gametocytes.
135
Chloroquine is useful against which species of malaria?
All non-falciparum Plasmodia species are sensitive to chloroquine. P. falciparum is often resistant to chloroquine. Areas where it may still be sensitive to
chloroquine include Central America, Haiti, Dominican Republic, and the Middle East.
136
For travel to chloroquine-resistant areas, which drugs are used for malaria prophylaxis?
Atovaquone/proguanil, mefloquine, or doxycycline can all be used in chloroquine-resistant areas.
137
What is the presentation of Babesia infection?
Babesia can present like malaria with a febrile hemolytic anemia. Symptoms can persist for months including fever, profuse sweats, myalgias, and shaking chills. Severe cases cause liver, renal, and neurologic failure and death. Hemoglobinuria is a predominant sign.
138
How do you diagnose and treat extraintestinal amebiasis?
Extraintestinal amebiasis is diagnosed via serologies. Intestinal amebiasis is diagnosed by examining stool for ova and parasites.
139
How is Giardia infection diagnosed?
Giardia can be diagnosed by microscopic examination of fresh stool samples, antigen detection, or nucleic acid amplification assays. The latter is the most sensitive.
140
What is kala-azar?
Kala-azar is visceral leishmaniasis caused by L. dovovani.
141
Strongyloides hyperinfection syndrome can be seen in which patient population?
Strongyloides hyperinfection syndrome is seen in immunosuppressed patients and may occur after a patient starts steroid therapy.
142
What is visceral larva migrans?
Migrating larvae of Toxocara may caused visceral larva migrans in which the migrating larvae cause injury to the liver (hepatomegaly), heart (myocarditis), lungs (fleeting
pulmonary infiltrates, SOB, cough, wheezing), brain (eosinophilic meningoencephalitis), muscle (myalgias) and eyes.
143
When do you not treat patients with neurocysticercosis with an antiparasitic drug?
If cerebral edema or a lot of inflammation is present with neurocysticercosis you should hold off on treating with antiparasitics and treat with steroids first.
144
Multinucleated giant cells can be seen with which infections?
Multinucleated giant cells are seen on Giemsa and Wright stains of elcer scrapings in HSV and VZV infections.
145
What is the most sensitive and specific method for diagnosing HSV encephalitis?
HSV PCR of CSF is the most sensitive and specific method for diagnosing HSV encephalitis.
146
Which patients should receive the zoster vaccination?
Zoster vaccination should be given to those over age 60 regardless of prior history of varicella or zoster.
147
How is CMV diagnosed?
CMV is diagnosed by demonstrating the DNA in peripheral blood via PCR.
148
What is the clinical presentation of EBV mononucleosis?
Most acute EBV infections are asymptomatic. If symptomatic >90% of patients have pharyngitis, which is typically exudative. Tonsillitis, fever, lymphadenopathy, and splenomegaly may be seen. A maculopapular rash is present in 20% of patients overall and in 90% of patients who are given ampicillin.
149
Which antibiotics target DNA gyrase to interrupt protein synthesis?
Quinolones block the ability of DNA gyrase to reconnect the cleaved DNA strands.
150
Which antibiotics antagonize folic acid?
Trimethoprim and sulfa drugs antagonize folic acid which is needed to replicate DNA.
151
How are gram-negative organisms inherently more resistant to antibiotics, compared to gram-positives?
Gram negative organisms have an outer membrane through which antibiotics have to pass via porins. Some Gram negative organisms have an inherent resistance to cell wall agents because of the shape of their porins.
152
Which class of antibiotics affects the developing bacterial cell wall?
Beta-lactams and glycopeptides interrupt bacterial cell wall synthesis.
153
What information does the disk diffusion test give you?
Disk diffusion can give information about sensitivity of organisms that do not grow well in automated media or against drugs that are not part of standard panels.
154
What is the specific definition of MIC and MBC?
Minimal Inhibitory Concentration (MIC) is the concentration of antibiotic that inhibits visible growth in vitro after 24 hours of incubation.
Minimal Bactericidal Concentration (MBC) is the concentration of antibiotic that kills the bacteria.
155
What is the difference between concentration-dependent and time-dependent killing?
Concentration-dependent killing means that killing increases as you increase the concentration of the drug above MIC. Aminoglycosides and quinolones exhibit
concentration-dependent killing. Time-dependent killing is related to how long the concentration of the drug remains above the organism’s MIC. Beta-lactams, macrolides, and glycopeptides all exhibit time-dependent killing. Aim is to keep the drug concentration above the MIC for >50% of the dosing interval.
156
What is the postantibiotic effect?
Postantibiotic effect is persistent killing of bacteria even after the concentration of the drug has fallen below the MIC. This is an effect of drugs that exhibit concentration-dependent killing.
157
In time-dependent killing, how long should a patient’s serum concentration of a drug be higher than the infecting organism’s MIC?
In time-dependent killing the drug concentration should be higher than the MIC for >50% of the dosing interval.
158
What is the spectrum of activity of penicillin?
Penicillin covers streptococci, sensitive enterococci, leptospirosis, Listeria, Pasteurella, and syphilis.
159
Nafcillin is the drug of choice for which organisms?
Nafcillin is the drug of choice for MSSA.
160
What coverage does ampicillin add over penicillin? Which important organisms does ampicillin not cover?
Ampicillin covers some basic Gram negative bacteria including H. influenzae, E. coli, Proteus mirabilis, and many strains of Salmonella and Shigella. Ampicillin does not
cover Klebsiella or Pseudomonas.
161
Which organisms do extended-spectrum penicillins cover?
Extending-spectrum penicillins add more resistant GNRs and Pseudomonas to the coverage of ampicillin.
162
BLIs are combined with which drugs?
BLIs are combined with ampicillin and extended-spectrum penicillins. Two cephalosporins (ceftazidime and ceftolozane) are also combined with BLIs.
163
Which cephalosporins have anaerobic activity?
The 2nd generation cephalosporins (cefoxitin and cefotetan) have anaerobic coverage. Cefepime (4th generation) also has limited anaerobic coverage.
164
3rd generation cephalosporins are known for their activity against which organisms?
3rd generation cephalosporins are stable against most beta-lactamases and have enhanced activity against pneumococci, H. influenzae, N. gonorrhoeae. GNR coverage is also enhanced over prior generations.
165
Which beta-lactam drug can be given to patients with a penicillin allergy?
Aztreonam can be given to penicillin allergic patients. It has only Gram negative coverage.
166
Which carbapenem should be avoided in those with seizures?
Imipenem should be avoided in patients with seizures.
167
Ertapenem is useful for treating diabetic infections in which type of setting?
Ertapenem is useful for outpatient parenteral treatment of diabetic foot infections. It is also useful abdominal, pelvic, skin, and soft tissue infections.
168
What is the drug of choice for staphylococcal pneumonia with a vancomycin MIC >2mcg/ml?
Linezolid is the drug of choice for vancomycin-resistant MRSA pneumonia.
169
What are the potential complications of linezolid use?
Linezolid is associated with thrombocytopenia, anemia, and leukopenia.
170
What type of killing do aminoglycosides exhibit?
Aminoglycosides exhibit concentration-dependent killing.
171
What can happen to ciprofloxacin if it is dosed with a multivitamin?
Ciprofloxacin can be chelated by the cations (Mg, and Ca) reducing their absorption.
172
Liposomal amphotericin B preparations are used in which circumstances? Against which fungi?
Liposomal amphotericin B is generally used to avoid toxicity. However, it is also more effective for infections involving the reticuloendothelial system, including cryptococcal meningitis and disseminated histoplasmosis.
173
Which candidal species are resistant to fluconazole?
Candida krusei is entirely resistant to fluconazole. Candida glabrata has some resistance
to fluconazole.
174
What are the indications for voriconazole?
Voriconazole is the drug of choice for Aspergillus. It is also effective against C. glabrata, C. krusei, Fusarium, and Scedosporium (Pseudallescheria).
175
What are the indications for caspofungin?
Caspofungin is the drug of choice for candidemia until sensitivities are known. It is also used in immunocompromised patients with Aspergillus when amphotericin B and voriconazole are not tolerated.
176
Which class of drugs should no longer be used to treat influenza A?
Amantadine and rimantadine should no longer be used for influenza.
177
Which vaccines contain a live virus? Which patients should not receive them?
Live virus vaccines should not be given to immunocompromised or pregnant patients.
These include MMR, Varicella, Zostavax, Smallpox, oral typhoid, BCG, Yellow fever.
178
Which vaccines are safe to administer to immunocompromised or pregnant patients?
Killed (inactivated) vaccines are safe for immunocompromised or pregnant patients.
These include Td, Tdap, HepA, Polio, Cholera, Rabies, Japanese encephalitis, Typhoid
polysaccharide, HepB, HPV, Pneumococcal vaccines (both), Meningococcal vaccine.
Trivalent influenza.
179
How many doses of MMR are considered most desirable and protective?
Two doses of MMR are most protective.
180
Which patient groups should receive the pneumococcal polysaccharide vaccine?
Patients >65 should receive PPSV23. It should be given to younger patients with chronic heart, lung, liver, or kidney disease. It is also indicated in diabetes, alcoholics, and cigarette smokers.
181
For whom should you check a post-vaccine hepatitis B titer?
Serologic testing for immunity after HepB vaccinations is indicated in healthcare and public safety workers, hemodialysis patients, HIV-infected persons,
immunocompromised persons, and sexual lpartners of HepBSAg+ persons.
182
Which patient groups should receive some form of the meningococcal vaccine?
At-risk populations for meningococcal disease are asplenic patients, complement deficiencies, 1st year college students in dorms, military recruits, people traveling to the Hajj or Nepal, and lab workers who work with Neisseria.
183
How do you decide how to prevent tetanus in a patient presenting with a wound? Is a crush injury “tetanus-prone”?
Decisions regarding how to treat a patient presenting with a wound depend on whether the wound is tetanus-prone and the state of vaccination of the patient. Crush wounds are considered tetanus-prone. Those who have had the 3 dose primary tetanus series with last dose >5 year earlier should receive Td. Those who have not had the primary series should get the Td plus TIG (tetanus immune globulin).
