ß-Lactam Therapy for Methicillin-Susceptible Staphylococcus aureus Bacteremia: A Comparative Review of Cefazolin versus Antistaphylococcal Penicillins.

Methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia is associated with high morbidity and mortality. Traditionally, antistaphylococcal penicillins (ASPs) have been considered the agents of choice for the treatment of MSSA bacteremia. Vancomycin has been demonstrated to have poorer outcomes in several studies and is only recommended for patients with severe penicillin allergies. Although cefazolin is considered as an alternative to the ASPs for patients with nonsevere penicillin allergies, cefazolin offers several pharmacologic advantages over ASPs, such as more convenient dosing regimens, and antimicrobial stewardship programs are increasingly using cefazolin as the preferential agent for MSSA infections as part of cost-saving initiatives. Concerns about susceptibility to hydrolysis by type A ß-lactamases, particularly at high inocula seen in deep-seated infections such as endocarditis; selective pressures from unnecessary gram-negative coverage; and lack of comparative clinical data have precluded recommending cefazolin as a first-line therapy for MSSA bacteremia. Recent clinical studies, however, have suggested similar clinical efficacy but better tolerability, with lower rates of discontinuation due to adverse drug reactions, of cefazolin compared with ASPs. Other variables, such as adequate source control (e.g., intravascular catheter removal, debridement, or drainage) and enhanced pharmacodynamics through aggressive cefazolin dosing, may mitigate the role of cefazolin inoculum effect and factor into determining improved clinical outcomes. In this review, we highlight the utility of cefazolin versus ASPs in the treatment of MSSA bacteremia with a focus on clinical efficacy and safety.

Ceftaroline as Salvage Monotherapy for Persistent MRSA Bacteremia.

OBJECTIVE: To summarize published data regarding the use of ceftaroline as salvage monotherapy for persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. DATA SOURCES: PubMed (January 1980-June 2016) was searched using combinations of the search terms methicillin-resistant Staphylococcus aureus, MRSA, bacteremia, ceftaroline, refractory, and persistent Supplemental references were generated through review of identified literature citations. STUDY SELECTION AND DATA EXTRACTION: Available English-language, full-text articles pertaining to the use of ceftaroline for persistent MRSA bacteremia (MRSAB) were included. DATA SYNTHESIS: The PubMed search yielded 23 articles for evaluation. There are no randomized controlled trials to date-only case series and reports. Four retrospective case series detailing the use of ceftaroline as monotherapy for persistent MRSAB were included. Most patients received at least 4 days of an appropriate anti-MRSA antimicrobial prior to ceftaroline and were able to clear bacteremia within 3 days. The most common rationales for ceftaroline use were progression of disease or nonresponse to current therapy. Higher off-label dosing of ceftaroline is often utilized to achieve optimal pharmacokinetic/pharmacodynamic parameters. Adverse events are not well described due to lack of follow-up; however, neutropenia has been associated with prolonged use. CONCLUSIONS: Treatment options for persistent MRSAB remain few and far between. Ceftaroline is an effective agent for the salvage treatment of MRSAB. Off-label doses up to 600 mg every 8 hours are often used to achieve optimal pharmacokinetic/pharmacodynamic parameters. Because of lack of follow-up in these reports, the incidence of adverse effects of prolonged use of ceftaroline is not well defined.

Monotherapy or combination therapy? The Pseudomonas aeruginosa conundrum.

Abstract The use of combination antibiotic therapy for severe pseudomonal infections is a standard practice in many hospitals; however, the data supporting its use are somewhat unclear. Possible benefits of combination therapy for Pseudomonas aeruginosa infections include in vitro antibiotic synergy, prevention of the emergence of bacterial resistance while receiving therapy, and improved adequacy of empiric therapy. Unfortunately, the potential disadvantages are also considerable, the most worrisome of which are drug toxicity and creation of multidrug-resistant organisms in the environment. Many in vitro and animal studies have attempted to shed light on this clinically challenging issue; however, these studies have often yielded conflicting results and used different study methods, which limits the clinical utility of the results. Clinical studies have also attempted to clarify this issue, particularly in patients with serious pseudomonal infections such as bacteremia and ventilator-associated pneumonia, but again, often resulted in conflicting conclusions. Thus, we performed a MEDLINE search (1950-May 2010) of clinical and in vitro studies evaluating the use of antibiotic combination therapy and monotherapy for bacteremia and pneumonia due to P. aeruginosa. Although a clear answer still eludes this controversy, combination therapy for seriously ill patients suspected of having pseudomonal infection has been shown, with considerable evidence, to improve the likelihood of an active agent being included in the initial antibiotic regimen of these patients. The clinical status of the patient and true likelihood of encountering a multidrug-resistant organism should be evaluated before deciding on empiric combination therapy. Future research may be able to better identify which patient populations might receive the most benefit from combination therapy rather than using combination therapy for everyone at risk for these infections.

A clinical pathway for community-acquired pneumonia: an observational cohort study.

BACKGROUND: Six hospitals instituted a voluntary, system-wide, pathway for community acquired pneumonia (CAP). We proposed this study to determine the impact of pathway antibiotics on patient survival, hospital length of stay (LOS), and total hospital cost. METHODS: Data were collected for adults from six U.S. hospitals with a principal CAP discharge diagnosis code, a chest infiltrate, and medical notes indicative of CAP from 2005-2007. Pathway and non-pathway cohorts were assigned according to antibiotics received within 48 hours of admission. Pathway antibiotics included levofloxacin 750 mg monotherapy or ceftriaxone 1000 mg plus azithromycin 500 mg daily. Multivariable regression models assessed 90-day mortality, hospital LOS, total hospital cost, and total pharmacy cost. RESULTS: Overall, 792 patients met study criteria. Of these, 505 (64%) received pathway antibiotics and 287 (36%) received non-pathway antibiotics. Adjusted means and p-values were derived from Least Squares regression models that included Pneumonia Severity Index risk class, patient age, heart failure, chronic obstructive pulmonary disease, and admitting hospital as covariates. After adjustment, patients who received pathway antibiotics experienced lower adjusted 90-day mortality (p = 0.02), shorter mean hospital LOS (3.9 vs. 5.0 days, p < 0.01), lower mean hospital costs ($2,485 vs. $3,281, p = 0.02), and similar mean pharmacy costs ($356 vs. $442, p = 0.11). CONCLUSIONS: Pathway antibiotics were associated with improved patient survival, hospital LOS, and total hospital cost for patients admitted to the hospital with CAP.

Effects of therapeutic drug monitoring criteria in a computerized prescriber-order-entry system on the appropriateness of vancomycin level orders.

PURPOSE: The effects of therapeutic drug monitoring (TDM) criteria in a computerized prescriber-order-entry (CPOE) system on the appropriateness of orders for vancomycin levels were evaluated. METHODS: Vancomycin TDM criteria were developed and implemented in a CPOE system. These criteria were displayed via a pop-up alert message when vancomycin levels were ordered and included directions for appropriate timing and justification for routine monitoring. Data for two groups of adult inpatients who had vancomycin levels ordered before and after criteria implementation were compared. Medical records were retrospectively reviewed for these patients to collect information regarding patient demographics, vancomycin dosage and indication, concurrent antibiotics and nephrotoxic agents during vancomycin therapy, length of stay, duration of vancomycin therapy, and number of vancomycin levels drawn. The primary outcome was the percent change in appropriate vancomycin levels ordered after criteria implementation. RESULTS: A total of 200 patients were analyzed, 100 in each group. The percentage of appropriate orders for vancomycin levels significantly increased after criteria implementation (from 58% to 68%, p = 0.02). The greatest effect on appropriateness occurred with the first level ordered (52% versus 70% in the preimplementation and postimplementation groups, respectively; p = 0.01). The majority of inappropriate levels were due to improper timing of sample collections, accounting for 55% of the inappropriate levels evaluated. CONCLUSION: A significant increase in the number of appropriately ordered and drawn serum vancomycin levels occurred after implementation of TDM criteria in the hospital's CPOE system. The majority of orders that were deemed inappropriate were due to improper timing of laboratory collection.