BCPS / Infectious disease

Answer D. Advanced age, previous antimicrobial usage, duration of hospitalization, cancer chemotherapy, GI surgery, tube feeding, and use of acid-suppressing medications.
Reference:
Cohen S, Gerding D, Johnson S et al. Clinical Practice Guidelines for Clostridium difficile Infection in Adults: 2010 Update by the Society for Healthcare Epidemiology of America (SHEA) and the Infectious Diseases Society of America (IDSA). Infection Control and Hospital Epidemiology. 2010;31(5):431-455. Doi: 10.1086/651706

Answer D. Primary treatment for stenotrophomonas maltophilia is SMX-TMP. Meropenem, ciprofloxacin, and vancomycin have no coverage.
Reference:
Gilbert D. The Sanford Guide to Antimicrobial Therapy 2014. Sperryville, Va.: Antimicrobial Therapy; 2014

Answer B. Ceftaroline covers MRSA, but it does not cover pseudomonas. Ertapenem does not cover pseudomonas. Cefepime has pseudomonas coverage.
Reference:
Gilbert D. The Sanford Guide to Antimicrobial Therapy 2014. Sperryville, Va.: Antimicrobial Therapy; 2014

Answer A. Meropenem is the drug of choice for ESBL empirically due to higher percentage of sensitivity. It can be de-escalated once culture and sensitivity available.
Reference:
Gilbert D. The Sanford Guide to Antimicrobial Therapy 2014. Sperryville, Va.: Antimicrobial Therapy; 2014

Answer C. A is wrong because ampicillin-sulbactam covers Acinetobacter and piperacillin-tazobactam has variable coverage for Acinetobacter. B. is wrong because neither ampicillin-sulbactam nor piperacillin-tazobactam covers ESBL. D. is wrong because both ampicillin-sulbactam and piperacillin-tazobactam cover anaerobes.
Reference:
Gilbert D. The Sanford Guide to Antimicrobial Therapy 2014. Sperryville, Va.: Antimicrobial Therapy; 2014.

Answer C. Since there is 70% of S. aureus isolate in the ICU that is methicillin resistant, vancomycin would be indicated since it is the only agent of the options given above that has activity against MRSA.
Reference:
Kalil AC, Metersky ML, Klompas M, et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;ciw353. doi:10.1093/cid/ciw353.

Answer D. These risk factors are listed in Table 2 of the guidelines. These factors were associated with an increased risk of MDR VAP in several studies. There is limited evidence for the potential risk factors studied for MDR HAP. However, prior IV antibiotic use is significantly associated with MDR HAP. This risk factor is also associated with MRSA VAP/HAP and MDR Pseudomonas VAP/HAP in which evidence is also limited.
Reference:
Kalil AC, Metersky ML, Klompas M, et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;ciw353. doi:10.1093/cid/ciw353.

Answer B. Purulent skin soft tissue infection are most likely caused by Staph. Aureus. Empiric antibiotic should be targeted to Staph. Aureus. Streptococcus is normally found from the Nonpurulent necrotizing Infections. E. Coli is normally found in the UTI and intra-abdominal infection. Pseudomonas aeruginosa is found in Diabetic wound and infections associated with burns.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection

Answer B. The IDSA SSTI treatment guidelines recommends treating empirically with doxycycline or SMX/TMP in patients presenting with moderate purulent SSTI. Since this patient has a sulfa allergy SMX/TMP cannot be used in this patient. Doxycycline is the drug of choice here. Linezolid would be appropriate if the patient was presenting with a severe purulent SSTI indicated by meeting SIRS criteria or previously failing antibiotic therapy.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer A. The ISDA SSTI guidelines recommend covering for MRSA in patients with an abscess who have failed initial antibiotic treatments or have SIRS. This patient has failed antibiotic treatment and meets the SIRS criteria. SMX/TMP cannot be used in this patient due to the patient’s allergy. Vancomycin with zosyn is not recommend for this type infection and clindamycin may be resisted since the patient has already failed the first round of treatment.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer B. Vancomycin, Linezolid, and SMX/TMP have MRSA coverage; Dicloxacillin does not. This patient happens to be allergic to sulfa drugs, which would include SMX/TMP. Vancomycin unfortunately has a very low bioavailability, so low in fact it cannot be used orally to treat an infection outside the GI tract; it would have to be given IV for this patient’s infection. Linezolid is the only option here because it can be absorbed through oral administration, has MRSA coverage, and does not contain a sulfa component.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer A. This patient is displaying signs of a severe case of cellulitis. Severe cellulitis is defined as having one of the following: failed oral antibiotic treatment, immunocompromised, clinical signs of deeper infection, or meeting the SIRS criteria. Based on this patient’s presentation they have failed antibiotic treatment and meet SIRS criteria. For severe cellulitis, IDSA SSTI guidelines recommend using Vancomycin along with Zosyn.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer A. This patient is showing signs of erysipelas. The patient does not appear to have a systemic infection, this indicates the infection is mild and can be treated effectively with oral medication in the outpatient setting. Linezolid and vancomycin are not recommended because MRSA is not suspected in this patient. Cephalexin has the most specific (narrow) coverage for streptococcus out of these antibiotics.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer C. The IDSA SSTI guidelines recommends using Doxycycline with either ceftriaxone or cefotaxime when the culture results show Vibrio vulnificus as the culprit.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer E. Cefazolin or an antistaphylococcal penicillin (oxacillin or nafcillin) is recommended for this patient because the C&S results indicate MSSA. Since the patient develops a rash to penicillins, it would be acceptable to use cefazolin in this case.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer C. For this type of infection, doxycycline, dicloxacillin, or cephalexin would be appropriate outpatient therapy. Since the patient has already been treated for a week, a minimum of 7 additional days of therapy is recommended. There is no need to give dicloxacillin for 21 days since IDSA recommends 2-3 weeks of therapy, also because the patient has an allergy to penicillins it is not recommended. Since the patient is improving on cefazolin, cephalexin is an appropriate oral medication to discharge the patient on.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer D. The IDSA guidelines recommend preemptive antimicrobial therapy in patients that are immunocompromised, asplenic, have advanced liver disease, have moderate to severe injuries, have injuries that may have penetrated the periosteum or joint capsule, or, as in this patient, has resultant edema of the affected area. The duration of this treatment is recommended for 3-5 days.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer E. The IDSA guidelines state that Pasteurella species are commonly cultured from animal bites, purulent and non-purulent.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer A. The IDSA guidelines recommends Augmentin for the initial treatment of an infection caused by an animal bite. Augmentin covers most of the aerobic and anaerobic bacteria that cause the infection. The other antibiotics listed here are not recommended, though ampicillin-sulbactam is recommended in the case of an infection caused by a human bite.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer A. The IDSA SSTI guidelines recommends antimicrobial agents active against gram-negative bacteria and anaerobes, such as cephalosporins or fluoroquinolones, to be used in combination with metronidazole when treating a surgical site infection following an operation on the axilla, GI tract, perineum, or, as with this patient, female genital tract. The patient is allergic to fluoroquinolones, so ciprofloxacin should not be used for this patient.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer D. The IDSA SSTI guidelines recommends the use of a first generation cephalosporin or an antistaphylococcal penicillin in patient with a surgical site infection. If MRSA is suspected vancomycin, linezolid, daptomycin, telavancin, or ceftaroline can be used. In this patient MRSA is not suspected so vancomycin is not needed. The other antibiotics listed here are used in cases following a surgical operation on the axilla, GI tract, perineum, or female genital tract.
Reference:
Stevens, Dennis L., et al. "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America." Clinical Infectious Diseases (2014): ciu296. Available at: https://academic.oup.com/cid/article/59/2/e10/2895845/Practice-Guidelines-for-the-Diagnosis-and Management of Skin and Soft Tissue Infection.

Answer D. A and B are incorrect because there is no MRSA coverage, and this patient has risk of MDR because she came from a nursing home. C is incorrect because Piperacillin/Tazobactam and cefepime provide duplicate coverage for pseudomonas. D. is the correct answer because she came from a nursing home she should be treated as having healthcare-care associated pneumonia risk for MDR. She should be started on IV empiric therapy with Vancomycin and Piperacillin/Tazobactam. Reference: Kalil AC, Metersky ML, Klompas M, et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;ciw353. doi:10.1093/cid/ciw353.

Answer D. The IDSA guidelines for CAP PNA list risk factors specific for pseudomonas which are alcoholism, structural lung diseases, such as bronchiectasis, or repeated exacerbations of severe COPD leading to frequent steroid and/or antibiotic use, On mechanical ventilator for >3 days, as well as prior antibiotic therapy. Reference: 1) Mandell L, Wunderink R, Anzueto A et al. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults. Clinical Infectious Diseases. 2007; 44 (Supplement 2):S27-S72. doi:10.1086/511159.
2) Kalil AC, Metersky ML, Klompas M, et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;ciw353. doi:10.1093/cid/ciw353.

The IDSA guidelines for CAP PNA list risk factors specific for MRSA, which are end-stage renal disease, injection drug abuse, prior influenza, and prior antibiotic therapy, especially with fluoroquinolones. Infection with the influenza virus has been shown to be a risk factor for MRSA. Other risk factors for multi-drug resistant HAP, VAP, and HCAP are previous use of antibiotics within the last 90 days, current hospitalization of 5 d or more, local high occurrence antibiotic resistance, immunosuppressive state, or risk factors for HCAP (2 or more days of hospitalization in past 30 days, residence in a long term care facility or nursing home, family member with multidrug-resistant pathogen, home wound care, family member with multidrug-resistant pathogen, chronic dialysis within the last 30 days, or home infusion therapy). Investigations have shown that fluoroquinolones are associated with predisposing patients to MRSA infections. Several case control study demonstrated that exposure to either levofloxacin or ciprofloxacin use was associated with MRSA infection but not MSSA. Reference: 1) Weber SG, Gold HS, Hooper DC, Karchmer AW, Carmeli Y. Fluoroquinolones and the Risk for Methicillin-resistant Staphylococcus aureus in Hospitalized Patients. Emerging Infectious Diseases. 2003;9(11):1415-1422. doi:10.3201/eid0911.030284
2) Mandell L, Wunderink R, Anzueto A et al. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults. Clinical Infectious Diseases. 2007;44(Supplement 2):S27-S72. doi:10.1086/511159.

Answer A. A is the correct answer because according to the IDSA CAP guidelines, antibiotics that should be started are a beta-lactam and either azithromycin or a fluoroquinolone for patients without penicillin allergy. For pseudomonas infections, empiric therapy can be with Piperacillin/Tazobactam plus levofloxacin or ciprofloxacin. B is wrong because this option does not include a beta-lactam. C and D are wrong because Piperacillin/Tazobactam is for pseudomonas infections. Vancomycin is inappropriate because this is community-acquired pneumonia and therefore the patient is not at risk for MRSA as he would be if he had healthcare or hospital acquired pneumonia. Reference: Mandell L, Wunderink R, Anzueto A et al. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults. Clinical Infectious Diseases. 2007;44(Supplement 2):S27-S72. doi:10.1086/511159.

Antibiotic treatment can be with a respiratory fluoroquinolone (levofloxacin or ciprofloxacin) alone. Another option is to give ceftriaxone plus a macrolide such as Azithromycin. A and C are incorrect because Levofloxacin monotherapy is sufficient. B is incorrect because a macrolide should be given with a 3rd generation cephalosporin. Azithromycin and Levofloxacin provides overlap in atypical coverage. Reference: Guidelines for the Management of Adults with Hospital-acquired, Ventilator-associated, and Healthcare-associated Pneumonia. Am J Respir Crit Care Med. 2005;171(4):388-416. doi:10.1164/rccm.200405-644st.