Jihad Bishara

Importance of appropriate empirical antibiotic therapy for methicillin-resistant Staphylococcus aureus bacteraemia

OBJECTIVES To document the effects of appropriate and inappropriate empirical antibiotic therapy on mortality in a cohort of patients with bacteraemia due to methicillin-resistant Staphylococcus aureus (MRSA) and to summarize effects with previous studies. METHODS In the retrospective cohort study, episodes of clinically significant MRSA bacteraemia during a 15 year period were included. Polymicrobial episodes were excluded unless MRSA was isolated in more than one bottle and co-pathogens were given appropriate empirical antibiotic treatment. Appropriate empirical treatment was defined as matching in vitro susceptibility and started within 48 h of blood-culture taking, except for single aminoglycosides or rifampicin. We assessed univariate and multivariate associations between appropriate empirical therapy and 30 day all-cause mortality. Multivariable analysis was conducted using backward stepwise logistic regression. We reviewed all studies assessing the effects of appropriate empirical antibiotic treatment on mortality for MRSA infections and compiled adjusted odds ratios (ORs) using a random effects meta-analysis. RESULTS Five hundred and ten episodes of MRSA bacteraemia were included. There were no cases of community-acquired infection. The 30 day mortality was 43.9% (224/510) and was stable throughout the study period. Mortality was significantly higher among patients receiving inappropriate (168/342, 49.1%) compared with those receiving appropriate (56/168, 33.3%) empirical antibiotic treatment, P = 0.001. In the adjusted analysis the OR was 2.15 [95% confidence interval (CI) 1.34-3.46]. Pooling of six studies using adequate methodology for the adjusted analysis resulted in an OR of 1.98 (95% CI 1.62-2.44). CONCLUSIONS Appropriate empirical antibiotic treatment has a significant survival benefit in MRSA bacteraemia. Treatment guidelines should consider this benefit.

Effectiveness and safety of colistin: prospective comparative cohort study

BACKGROUND Colistin has re-entered clinical use by necessity. We aimed to assess its effectiveness and safety compared with newer antibiotics. METHODS This was a single-centre, prospective cohort study. Inclusion criteria were microbiologically documented pneumonia, urinary tract infection, surgical site infection, meningitis or bacteraemia treated appropriately with colistin versus imipenem, meropenem or ampicillin/sulbactam (comparators). All consecutive patients were included, only once, between May 2006 and July 2009. The primary outcome was 30 day mortality. Multivariable and Cox regression survival analyses were used to adjust comparisons between groups. Odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals are reported. RESULTS Two hundred patients treated with colistin and 295 patients treated with comparators were included. Treatment with colistin was associated with older age, admission from healthcare facilities, mechanical ventilation and lower rate of early appropriate antibiotic treatment. The 30 day mortality was 39% (78/200) for colistin versus 28.8% (85/295) for comparators; unadjusted OR 1.58 (1.08-2.31). In the adjusted analysis the OR was 1.44 (0.91-2.26) overall and 1.99 (1.06-3.77) for bacteraemic patients (n = 220). At the end of follow-up, treatment with colistin was significantly associated with cumulative mortality; adjusted HR 1.27 (1.01-1.60) overall and 1.65 (1.18-2.31) among patients with bacteraemia. Nephrotoxicity at the end of treatment was more frequent with colistin; OR adjusted for other risk factors for nephrotoxicity 3.31 (1.54-7.08). Treatment with colistin was followed by increased incidence of Proteus spp. infections during a 3 month follow-up. CONCLUSIONS The need for colistin treatment is associated with poorer survival. Adjusted analyses suggest that colistin is less effective and more toxic than beta-lactam antibiotics.

Treatment of human brucellosis: systematic review and meta-analysis of randomised controlled trials

Objectives To determine and quantify differences in efficacy between treatment regimens for brucellosis. Design Systematic review and meta-analysis of randomised controlled trials assessing different antibiotic regimens and durations of treatment for human brucellosis. Data sources PubMed, CENTRAL, Lilacs, conference proceedings, and bibliographies with no restrictions on language, study year, or publication status. Review methods Search, application of inclusion and exclusion criteria, data extraction, and assessment of methodological quality independently performed in duplicate. Primary outcomes were relapse and overall failure resulting from primary failure or relapse. Relative risks with 95% confidence intervals were calculated and pooled with a fixed effect model. Results 30 trials and 77 treatment arms were included. Overall failure was significantly higher with doxycycline-rifampicin compared to doxycycline-streptomycin, mainly due to a higher rate of relapse (relative risk 2.80, 95% confidence interval 1.81 to 4.36; 13 trials, without heterogeneity). Results were consistent among patients with bacteraemia and complicated brucellosis. Doxycycline-streptomycin resulted in a significantly higher rate of failure than doxycycline-rifampicin-aminoglycoside (triple drug regimen) (2.50, 1.26 to 5.00; two trials). Gentamicin was not inferior to streptomycin (1.45, 0.52 to 4.00 for failure; two trials). Quinolones combined with rifampicin were significantly less effective than doxycycline combined with rifampicin or streptomycin (1.83, 1.11 to 3.02, for failure; five trials). Monotherapy was associated with a higher risk of failure than combined treatment when administered for a similar duration (2.56, 1.55 to 4.23; five trials). Treatment for six weeks or more offered an advantage over shorter treatment durations. Conclusions There are significant differences in effectiveness between currently recommended treatment regimens for brucellosis. The preferred treatment should be with dual or triple regimens including an aminoglycoside.

Evaluation of CHROMagar KPC for Rapid Detection of Carbapenem-Resistant Enterobacteriaceae

ABSTRACT A new CHROMagar KPC medium was compared to MacConkey agar with carbapenem discs and PCR for the blaKPC gene for rapid detection of carbapenem-resistant Klebsiella pneumoniae. The sensitivity and specificity relative to PCR were 100% and 98.4%, respectively, for CHROMagar KPC and 92.7% and 95.9%, respectively, for MacConkey agar.

Are all beta-lactams similarly effective in the treatment of methicillin-sensitive Staphylococcus aureus bacteraemia?

Methicillin-sensitive Staphylococcus aureus (MSSA) is susceptible to many beta-lactams. We compared cloxacillin and cefazolin, the first-line recommended antibiotics, and other beta-lactams in the treatment of MSSA bacteraemia. This was a retrospective cohort study. Included were adult patients with clinically-significant MSSA bacteraemia treated with a beta-lactam that was started within 48 h after blood cultures were taken. We separated between empirical treatment administered to the patient before receipt of final blood culture results and definitive treatment administered thereafter. Univariate and multivariable analyses for 30-day (empirical treatment) and 90-day (definitive treatment) mortality were conducted, including the type of beta-lactam administered to the patient. Five-hundred and forty-one patients were included for the analysis of empirical treatment and 498 patients alive at 7 days were evaluable for definitive treatment. Empirical treatment with cloxacillin or cefazolin (n = 131) was associated with lower 30-day mortality as compared with cefuroxime (n = 98, p 0.058), ceftriaxone or cefotaxime (n = 194, p 0.008) and beta-lactam-beta-lactamase combinations (n = 61, p 0.013), with adjusted odds ratios (OR) for death ranging from 1.98 to 2.68. Definitive treatment with cefazolin (n = 72) was not significantly different from cloxacillin (n = 281); adjusted OR for 90-day mortality 0.91 (95% confidence interval 0.47-1.77). Treatment with cefazolin both in the empirical and definitive periods was not significantly different from cloxacillin; adjusted OR 0.81 (95% confidence interval 0.18-3.62). Treatment of MSSA bacteraemia with cefazolin is not significantly different from treatment with cloxacillin, while treatment with other beta-lactams, including second and third generation cephalosporins, might be associated with higher mortality.

Long-Term Outcome of Infective Endocarditis: The Impact of Early Surgical Intervention

To determine the impact of early surgical intervention on long-term survival in patients with infective endocarditis (IE), charts of all patients who had IE from January 1987 through December 1996 were reviewed. A total of 252 patients with definite or possible IE were included. Forty-four patients (17.5%) had early surgery on median hospital day 2 (range, 0-30 days), and 208 patients (82.5%) received medical treatment alone. On multivariate analysis, several variables, including early surgical intervention, improved long-term survival rates (hazard ratio, 1.5; P=.03), mainly in patients with Staphylococcus aureus etiology (P=.04). When patients with prosthetic devices were excluded, the median duration of survival for patients who had early surgery was >150 months, compared with 61.5 months for patients in the medical group (P=.1). Early surgical intervention compared with medical therapy alone is associated with increased short- and long-term survival rates in patients with IE, primarily when IE is caused by S. aureus.

Antibiotic Exposure as a Risk Factor for Fluconazole-Resistant Candida Bloodstream Infection

ABSTRACT Recent exposure to azoles is an important risk factor for infection with fluconazole-resistant Candida spp., but little is known about the role of antibacterial drug exposure in the emergence of drug-resistant Candida. We did a prospective nationwide surveillance study of candidemia in Israel and analyzed the propensity score-adjusted association between antifungal and antibacterial drug exposure and bloodstream infection with C. glabrata and fluconazole-resistant Candida isolates. Four hundred forty-four episodes of candidemia (450 Candida isolates, 69 [15%] C. glabrata isolates, and 38 [8.5%] fluconazole-resistant isolates) from 18 medical centers in Israel were included. C. glabrata bloodstream infection was strongly associated with recent metronidazole exposure (odds ratio [OR], 3.2; P < 0.001). Infection with a fluconazole-resistant isolate was associated with exposure to carbapenems, trimethoprim-sulfamethoxazole, clindamycin, and colistin (odds ratio, 2.8; P = 0.01). The inclusion of antibacterial drug exposure in a multivariable model significantly enhanced the models predictive accuracy for fluconazole-resistant Candida bloodstream infection. Our findings may be relevant to the selection of empirical antifungal treatment and broaden the scope of antibiotic-associated collateral damage.

Mortality of patients with antibiotic-associated diarrhoea: the impact of Clostridium difficile

Previous studies have shown conflicting results concerning mortality related to Clostridium difficile infection. The objective of this study was to determine the impact of C. difficile infection on short- and long-term mortality in hospitalised patients with antibiotic-associated diarrhoea. We therefore undertook a prospective case-control study of 217 hospitalised patients who received antibiotics, developed diarrhoea and underwent stool enzyme immunoassay for C. difficile TOX A/B. The Kaplan-Meier and the log-rank test were used to determine univariate survival analysis and a Cox regression model for multivariate analysis of 28 day and long-term mortality. Fifty-two (24%) of the 217 patients who met the study criteria were positive for C. difficile TOX A/B. The crude 28 day and long-term mortality rates of the entire cohort were 12.4% and 56%, respectively. On Cox regression analysis, hypoalbuminaemia, impaired functional capacity and elevated serum urea levels were found to be the only independent and statistically significant variables associated with long-term mortality. C. difficile toxin positivity per se was not associated with increased short- or long-term mortality rates. In conclusion, hypoalbuminaemia, renal failure, and impaired function capacity predict mortality due to antibiotic-associated diarrhoea, but C. difficile involvement by itself does not further increase the risk of death in these patients.

Predicting Clostridium difficile toxin in hospitalized patients with antibiotic-associated diarrhea.

OBJECTIVE Clostridium difficile infection is implicated in 20%-30% of cases of antibiotic-associated diarrhea. Studying hospitalized patients who received antibiotic therapy and developed diarrhea, our objective was to compare the clinical characteristics of patients who developed C. difficile-associated diarrhea (CDAD) with those of patients with a negative result of a stool assay for C. difficile toxin. METHODS A prospective study was done with a cohort of 217 hospitalized patients who had received antibiotics and developed diarrhea. Patients with CDAD were defined as patients who had diarrhea and a positive result for C. difficile toxin A/B by an enzyme immunoassay of stool. The variables that yielded a significant difference on univariate analysis between patients with a positive assay result and patients with a negative assay result were entered into a logistic regression model for prediction of C. difficile toxin.Setting. A 900-bed tertiary care medical center. RESULTS Of 217 patients, 52 (24%) had a positive result of assay for C. difficile toxin A/B in their stool. The logistic regression model included impaired functional capacity, watery diarrhea, use of a proton pump inhibitor, use of a histamine receptor blocker, leukocytosis, and hypoalbuminemia. The area under the receiver operating characteristic curve for the model as a predictor of a positive result for the stool toxin assay was 0.896 (95% confidence interval, 0.661-1.000; P<.001), with 95% specificity and 68% sensitivity. CONCLUSIONS Our results may help clinicians to predict the risk of CDAD in hospitalized patients with antibiotic-associated diarrhea, to guide careful, specific empirical therapy, and to direct early attention to infection control issues.

Trimethoprim-sulfamethoxazole versus vancomycin for severe infections caused by meticillin resistant Staphylococcus aureus: randomised controlled trial

Objective To show non-inferiority of trimethoprim-sulfamethoxazole compared with vancomycin for the treatment of severe infections due to meticillin resistant Staphylococcus aureus (MRSA). Design Parallel, open label, randomised controlled trial. Setting Four acute care hospitals in Israel. Participants Adults with severe infections caused by MRSA susceptible to trimethoprim-sulfamethoxazole and vancomycin. Patients with left sided endocarditis, meningitis, chronic haemodialysis, and prolonged neutropenia were excluded. Interventions Trimethoprim-sulfamethoxazole 320 mg/1600 mg twice daily versus vancomycin 1 g twice daily for a minimum of seven days and then by indication. Main outcome measures The primary efficacy outcome was treatment failure assessed at day 7, consisting of death, persistence of haemodynamic instability or fever, stable or worsening Sequential Organ Failure Assessment score, and persistence of bacteraemia. The primary safety outcome was all cause mortality at day 30. Non-inferiority was defined by a difference of less than 15% for treatment failure. Results 252 patients were included in the trial, of whom 91 (36%) had bacteraemia. No significant difference in treatment failure was seen for trimethoprim-sulfamethoxazole (51/135, 38%) versus vancomycin (32/117, 27%)—risk ratio 1.38 (95% confidence interval 0.96 to 1.99). However, trimethoprim-sulfamethoxazole did not meet the non-inferiority criterion—absolute difference 10.4% (95% confidence interval −1.2% to 21.5%). For patients with bacteraemia, the risk ratio was 1.40 (0.91 to 2.16). In a multivariable logistic regression analysis, trimethoprim-sulfamethoxazole was significantly associated with treatment failure (adjusted odds ratio 2.00, 1.09 to 3.65). The 30 day mortality rate was 32/252 (13%), with no significant difference between arms. Among patients with bacteraemia, 14/41 (34%) treated with trimethoprim-sulfamethoxazole and 9/50 (18%) with vancomycin died (risk ratio 1.90, 0.92 to 3.93). Conclusions High dose trimethoprim-sulfamethoxazole did not achieve non-inferiority to vancomycin in the treatment of severe MRSA infections. The difference was particularly marked for patients with bacteraemia. Trial registration Clinical trials NCT00427076.