In my experience, hospitalists usually have a greater knowledge of antibiotics and treatment of infections than other non-infectious disease (ID) practitioners who manage hospital patients. But that doesn’t stop ID physicians from wanting to make suggestions. The following list is not meant to be all-inclusive, but it does reflect an informal poll of my colleagues at a tertiary care medical center. Any opinions are of course my own, and naturally are evidenced based. There is an old joke that if you ask two ID doctors a question you get three answers. Having said that, I believe that there is a good consensus on these issues.
1. Beta-lactam/beta-lactamase inhibitors have excellent anaerobic coverage.
Beta-lactam/beta-lactamase inhibitors such as ampicillin/sulbactam and piperacillin/tazobactam have excellent anaerobic coverage. When treating suspected or proven anaerobic infections with these drugs, addition of other agents such as metronidazole and clindamycin to cover anaerobic infections is not necessary (1). Quite often we see patients treated with ampicillin/sulbactam and metronidazole or piperacillin/tazobactam and metronidazole, which is not necessary and potentially exposes the patient to additional drug toxicities. “Unasyn and Flagyl” for suspected intra-abdominal infections provides unnecessary double coverage for anaerobes, while providing suboptimal coverage for gram-negative rods due to increasing resistance to ampicillin/sulbactam among gram-negative aerobes.
2. Staphylococcus aureus bacteremia “always” gets at least 2 weeks of IV antibiotics.
Clinicians managing patients who have blood cultures positive for Staphylococcus aureus should always think about whether the patient has a deep-seated source such as cardiac or bone, and treat accordingly. But even patients with a self-limited bacteremia related to an intravenous catheter or other easily removable source of infection should get at least 2 weeks of antibiotics (2). One of the goals of treating S. aureus bacteremia is to prevent metastatic infection. Patients with line-related infections may have rapid clinical improvement and resolve the bacteremia quickly, but they are at high risk for relapse with bone, joint, or cardiac infection if the initial antimicrobial course is inadequate. At least once every year or 2 at our teaching hospitals we see a patient who is given a very short course of antibiotics for S. aureus bacteremia related to an intravenous catheter who returns a month or two later with relapse in the spine or in other equally serious sites of infection. It is believed that more aggressive initial antimicrobial therapy can prevent metastatic infections. A frequently employed strategy in evaluating patients with S. aureus bacteremia is to complete a transesophageal echocardiogram to rule out cardiac involvement. If there is no cardiac involvement and other deep seated source such as bone or joint are not suspected, 2 weeks of intravenous antibiotics are generally adequate. In the setting of cardiac involvement or deep-seated involvement in bone or joints, 4–6 weeks of antibiotics are required. Patients with staphylococcal bacteremia who do not have a known source of infection should almost always be treated for 4–6 weeks. And, of course, there is the usual caveat: Oral antibiotics with excellent oral bioavailability such as linezolid can be used as switch therapy to complete a 2-week course in some cases. But the default approach would be to treat all S. aureus bacteremias with at least 2 weeks of intravenous antibiotics.
3. Staphylococcus aureus in the urine should almost always prompt a search for another site of infection.
Patients who have Foley catheters or are status post-genitourinary procedures may develop primary S. aureus urinary tract infection, but it is unusual for patients without history of genitourinary manipulation to present with S. aureus as a cause of urinary tract infection. In patients with no predisposing factors for S. aureus urinary infection, isolation of the organism in the urine should always prompt an evaluation for another site of infection such as bone, joint, or endovascular. Patients with known or suspected S. aureus urinary tract infection should have blood cultures drawn prior to the initiation of antibiotics to detect occult bacteremias. It is not unusual on our Infectious Disease Consult Service to see a patient who is suspected of having a S. aureus UTI that is later shown after consultation and investigation to have S. aureus endocarditis without other obvious manifestations, or another deep-seated infection such as spinal osteomyelitis or epidural abscess.