Clinical Outcomes with Penicillin Versus Alternative β-Lactams in the Treatment of Penicillin-Susceptible Staphylococcus aureus Bacteremia

Treatment outcomes with benzylpenicillin and non-benzylpenicillin antibiotics, and the performance of the penicillin zone-edge test versus molecular detection of blaZ in penicillin-susceptible Staphylococcus aureus (PSSA) bacteraemia

OBJECTIVES

The blaZ gene encodes penicillinase, which inactivates penicillin. As there were reports on suboptimal sensitivity for the penicillin zone-edge test, a phenotypic method for blaZ detection, we investigated treatment outcomes in patients with penicillin-susceptible Staphylococcus aureus (PSSA) bacteraemia (phenotypically negative for penicillinase), subjecting isolates to molecular testing for blaZ retrospectively.

PATIENTS AND METHODS

A retrospective cohort study was conducted on 121 patients with a first episode of PSSA bacteraemia from 1 January 2012 to 31 October 2015 at Tan Tock Seng Hospital (TTSH), Singapore. Patients were grouped into IV benzylpenicillin and non-benzylpenicillin groups. The primary outcome was overall treatment failure, defined as either 30 day all-cause mortality and/or 90 day relapse. The penicillin (P10) zone-edge test was repeated on archived PSSA isolates, concurrently with penicillin MIC determination via gradient diffusion and PCR for blaZ.

RESULTS

Among 121 patients, 57 patients (47.1%) received IV benzylpenicillin as the predominant antibiotic. There was no significant difference in overall treatment failure between treatment with the benzylpenicillin [7/57 (12.3%)] versus non-benzylpenicillin groups [12/64 (18.8%)] (P = 0.33) or cloxacillin/cefazolin [6/37 (16.2%)] (P = 0.59). For 112 PSSA isolates available for testing, repeat penicillin zone-edge testing was negative for penicillinase production, corroborating previous results. A single PSSA isolate with a negative penicillin zone-edge test was found to be positive for blaZ.

CONCLUSIONS

We found no differences in overall treatment failure between patients with PSSA bacteraemia treated with benzylpenicillin, anti-staphylococcal β-lactams cefazolin/cloxacillin and other antimicrobials, when using the penicillin zone-edge test as the phenotypic method for blaZ screening.

Clinical Outcomes of Daptomycin Versus Anti-Staphylococcal Beta-Lactams in Definitive Treatment of Methicillin-susceptible Staphylococcus aureus Bloodstream Infections

OBJECTIVES

Staphylococcus aureus (S. aureus) is the leading cause of bacteraemia and infective endocarditis worldwide. The preferred management of patients with methicillin-susceptible S. aureus (MSSA) bacteraemia includes definitive therapy with intravenous anti-staphylococcal beta-lactam (ASBL) antibiotics. Daptomycin (DAP) has been targeted as a viable substitute for beta-lactam allergic or intolerant patients.

METHODS

This single-center retrospective cohort study assessed clinical outcomes of DAP compared with ASBL antibiotics [nafcillin (NAF) or cefazolin (CFZ)] for the treatment of MSSA bacteraemia in patients hospitalised from 01 November 2011 to 31 October 2018. The primary outcome was a composite of the following: clinical failure, MSSA recurrence and MSSA persistence or inpatient infection-related mortality. Secondary outcomes included duration of MSSA bacteraemia, infection-related length of stay, infection-related 90-day readmission, 30-day all-cause mortality, and adverse events necessitating a change in therapy.

RESULTS

Of 89 patients with MSSA bacteraemia who were included: 29 received DAP, 30 received NAF and 30 received CFZ. There was no difference in the composite primary outcome in patients treated with DAP compared with ASBL (10% vs. 5%, P = 0.39). The DAP cohort had a longer hospital length of stay compared with the ASBL group (20 days vs. 11.5 days, P = 0.0007). No differences were detected between other secondary outcomes.

CONCLUSION

This study suggests that DAP may serve as a comparable alternative to ASBLs for treatment of MSSA bacteraemia, as no differences in clinical outcomes were identified. Larger studies are needed to confirm these findings.

Defining the Breakpoint Duration of Staphylococcus aureus Bacteremia Predictive of Poor Outcomes

BACKGROUND

Persistent Staphylococcus aureus bacteremia (SAB) is defined based on varying duration in literature. The primary objective was to determine the risk of poor outcomes in relation to bacteremia duration.

METHODS

Multicenter, prospective, observational study of adult hospitalized patients with SAB. Medical records were reviewed for pertinent data. Patients were grouped by bacteremia duration: short (1-2 days), intermediate (3-6 days), and prolonged (≥7 days) and compared for risk factors and outcomes.

RESULTS

Of 884 patients, 63% had short, 28% intermediate, and 9% prolonged bacteremia. Overall mean age was 57 years, and 70% were male. The prolonged group had the highest proportion of methicillin-resistant SAB (P < .0001). Choice of antibiotic therapy did not significantly affect bacteremia duration; however, time to source-control procedure was delayed in the prolonged and intermediate groups compared with the short group (3.5 vs 3 vs 1 day, P < .0001). Metastatic complications, length of stay, and 30-day mortality were progressively worse as bacteremia duration increased (P < .0001). Every continued day of bacteremia was associated with a relative risk of death of 1.16 (95% confidence interval, 1.10-1.22; P < .0001), with a significant increase in risk starting at 3 days as determined by receiver operating characteristic analysis.

CONCLUSIONS

Optimal management of SAB should target bacterial clearance as soon as possible to minimize incremental risk of mortality with each day of positive blood culture. Delay in source control but not type of antistaphylococcal therapy was significantly associated with prolonged bacteremia and worse outcomes.

Comparison of penicillins (penicillin G and ampicillin) and cefazolin as a definitive therapy against penicillin-susceptible Staphylococcus aureus (PSSA) bacteremia in Japan: a retrospective cohort study

OBJECTIVES

Cefazolin has been the first-choice drug to treat penicillin-susceptible Staphylococcus aureus (PSSA) bacteremia, because oxacillin and nafcillin are not approved in Japan. Since February 2019, cefazolin supply is stagnant in Japan because of possible contamination issues. To look for cefazolin alternatives that can be used as a definitive therapy, we evaluated the usefulness of penicillins (penicillin G and ampicillin) against PSSA bacteremia.

METHODS

A retrospective cohort study of patients with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia was conducted between January 2012 and September 2017. MSSA was determined according to the Clinical and Laboratory Standards Institute guidelines. PSSA was defined as S. aureus with penicillin G minimum inhibitory concentration of ≤0.03 mg/L without using the zone edge test or blaZ PCR.

RESULTS

Of the 280 patients with MSSA bacteremia enrolled, and 138 (49.3%) was PSSA. Of the 44 patients who met the inclusion criteria, 11 were administered penicillins (penicillin G, n = 3 and ampicillin, n = 8) and 33 with cefazolin. Although the patients in the two groups had similar demographics, those in the penicillins group had significantly lower median Charlson score [interquartile range] than those in the cefazolin group (0[0-1] vs 1[0-4], p = 0.033). The two groups showed no significant differences regarding adverse events and bacteremia recurrence. None of the patients in the penicillins group died; however, 5 (15.2%) patients in the cefazolin group showed a 30-days mortality.

CONCLUSION

Penicillins can be useful as a definitive therapy against PSSA bacteremia with stable condition, and they can be an alternative to cefazolin.

Cefazolin Versus Anti-Staphylococcal Penicillins for the Treatment of Patients with Methicillin-Susceptible Staphylococcus aureus Infection: A Meta-Analysis with Trial Sequential Analysis

INTRODUCTION

Methicillin-susceptible Staphylococcus aureus (MSSA) is a common cause of infection in humans. Beta-lactam antibiotics are the preferred agents, with anti-staphylococcal penicillins (ASPs) or the first-generation cephalosporin, cefazolin, favored by clinicians. Recent studies comparing the two strategies suggest similar outcomes between the agents. The purpose of this meta-analysis was to explore differences between cefazolin and ASPs for the treatment of MSSA infections.

METHODS

We performed a meta-analysis with trial sequential analysis (TSA) of observational or cohort studies using a random-effects model. Two blinded reviewers independently assessed studies for inclusion, risk of bias, and data extraction. The primary outcome was all-cause mortality. Secondary outcomes included clinical failure, infection recurrence, and antibiotic discontinuation due to adverse events. Subgroup analyses were conducted for the primary outcome by type of ASP, studies with a high percentage of deep-seated infections, and studies of low to moderate risk of bias.

RESULTS

After performing a comprehensive search of the literature, and screening for study inclusion, 19 studies (13,390 patients) were included in the final meta-analysis. Fifteen of the 19 studies (79%) were judged as having a low or moderate risk of bias. Use of cefazolin was associated with lower all-cause mortality [odds ratio (OR) 0.71, 95% confidence interval (CI) 0.56-0.91, p = 0.006, I2 = 28%], clinical failure (OR 0.55, 95% CI 0.41-0.74, p < 0.001, I2 = 0%), and antibiotic discontinuation due to adverse events (OR 0.25, 95% CI 0.16-0.39, p < 0.001, I2 = 23%). Infection recurrence was higher in the cefazolin patients (OR 1.41, 95% CI 1.04-1.93, p = 0.03, I2 = 0%).

CONCLUSION

This meta-analysis demonstrated that the use of cefazolin was associated with significant reductions in all-cause mortality, clinical failure, and discontinuation due to adverse events, but was associated with an increased risk of infection recurrence.

FUNDING

University of Florida Open Access Publishing Fund funded the Rapid Service Fees.

TRIAL REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews (study ID: CRD42018106442).

Comparative Effectiveness of Exclusive Exposure to Nafcillin or Oxacillin, Cefazolin, Piperacillin/Tazobactam, and Fluoroquinolones Among a National Cohort of Veterans With Methicillin-Susceptible Staphylococcus aureus Bloodstream Infection

Objective

Beta-lactam antibiotics are recommended as first-line for treatment of methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia. The objective of this study was to compare effectiveness of anti-MSSA therapies among bacteremia patients exclusively exposed to 1 antimicrobial.

Method

This was a national retrospective cohort study of patients hospitalized in Veterans Affairs medical centers with MSSA bacteremia from January 1, 2002, to October 1, 2015. Patients were included if they were treated exclusively with nafcillin, oxacillin, cefazolin, piperacillin/tazobactam, or fluoroquinolones (moxifloxacin and levofloxacin). We assessed 30-day mortality, time to discharge, inpatient mortality, 30-day readmission, and 30-day S. aureus reinfection. Hazard ratios (HRs) and 95% confidence intervals (CI) were calculated using propensity-score (PS) matched Cox proportional hazards regression model.

Results

When comparing nafcillin/oxacillin (n = 105) with cefazolin (n = 107), 30-day mortality was similar between groups (PS matched n = 44; HR, 0.67; 95% CI, 0.11-4.00), as were rates of the other outcomes assessed. As clinical outcomes did not vary between nafcillin/oxacillin and cefazolin, they were combined for comparison with piperacillin/tazobactam (n = 113) and fluoroquinolones (n = 103). Mortality in the 30 days after culture was significantly lower in the nafcillin/oxacillin/cefazolin group compared with piperacillin/tazobactam (PS matched n = 48; HR, 0.10; 95% CI, 0.01-0.78), and similar when compared with fluoroquinolones (PS matched n = 32; HR, 1.33; 95% CI, 0.30-5.96).

Conclusions

In hospitalized patients with MSSA bacteremia, no difference in mortality was observed between nafcillin/oxacillin and cefazolin or fluoroquinolones. However, higher mortality was observed with piperacillin/tazobactam as compared with nafcillin/oxacillin/cefazolin, suggesting it may not be as effective as a monotherapy in MSSA bacteremia.

Twenty-Year Trends in Antimicrobial Susceptibilities Among Staphylococcus aureus From the SENTRY Antimicrobial Surveillance Program

Background

Staphylococcus aureus is among the most common human pathogens, with therapy complicated by the epidemic spread of methicillin-resistant Staphylococcus aureus (MRSA).

Methods

The SENTRY Antimicrobial Surveillance Program evaluated the in vitro activity of >20 antimicrobials against 191 460 clinical S. aureus isolates collected from 427 centers in 45 countries from 1997 to 2016. Each center contributed isolates and clinical data for consecutive episodes of bacteremia, pneumonia in hospitalized patients, urinary tract infection, and skin and skin structure infection.

Results

Overall, 191 460 S. aureus isolates were collected, of which 77 146 (40.3%) were MRSA, varying geographically from 26.8% MRSA in Europe to 47.0% in North America. The highest percentage of MRSA was in nosocomial isolates from patients aged >80 years. Overall, MRSA occurrences increased from 33.1% in 1997-2000 to a high of 44.2% in 2005-2008, then declined to 42.3% and 39.0% in 2009-2012 and 2013-2016, respectively. S. aureus bacteremia had a similar trend, with nosocomial and community-onset MRSA rates peaking in 2005-2008 and then declining. Vancomycin activity against S. aureus remained stable (minimum inhibitory concentration [MIC]₉₀ of 1 mg/L and 100% susceptibility in 2016; no increase over time in isolates with a vancomycin MIC >1 mg/L). Several agents introduced during the surveillance period exhibited in vitro potency against MRSA.

Conclusions

In a large global surveillance program, the rise of MRSA as a proportion of all S. aureus peaked a decade ago and has declined since, consistent with some regional surveillance program reports. Vancomycin maintained high activity against S. aureus, and several newer agents exhibited excellent in vitro potencies.

Evolution of haemostatic parameters and risk of bleeding during treatment with cefazolin

In 2017, five cases of severe haemorrhages during treatment with cefazolin occurred in France. The aim of this study was to assess the risk of haemorrhage related to treatment with cefazolin by evaluating haemostatic parameters and bleeding events. A retrospective study was conducted from January 2016 to December 2017. Two populations were analysed: (i) overall population, which included all patients treated with cefazolin during this period and (ii) coagulation study population, which included all patients treated with cefazolin with available coagulation parameters (activated partial thromboplastin time (aPTT) and international normalised ratio (INR) at baseline and at the end of treatment or EoT). Values of either aPTT or INR at baseline and at EoT were compared. Cases of severe haemorrhages were reported and correlated with values of aPTT and INR. Overall, 132 patients received cefazolin and 59/132 (45%) were included in the coagulation study group. A significant increase of median aPTT was observed from baseline to EoT (39.5 and 44.3 sec; p = 0.004, respectively). Overall, severe haemorrhage occurred in 7/132 (5%) patients. Coagulation parameters were available in three of them, and no correlation was observed between bleeding events and aPTT increase. This study showed that bleeding is probably more frequent than ever reported before during cefazolin treatment. The significant increase of aPTT observed during cefazolin treatment was not correlated with risk of haemorrhage. Further studies are needed to explore the possible physio-pathological pathways behind the modification of haemostatic parameters and risk of haemorrhage.