Comparative in vitro activity of piperacillinl tazobactam against Gramnegative bacilli

Objective. To describe the in vitro activity of piperacillinl tazobactam against clinical isolates of Gram-negative bacteria, compared with other antibacterial agents.Design. Survey of susceptibility of clinical isolates of Gram-negative bacilli.Setting. Academic hospitals of the University of the Witwatersrand teaching complex. Bacterial strains_ 180 selected clinical isolates of Gramnegative bacilli.Main outcome measures. Minimum inhibitory concentrations (MICs) determined by agar dilution using techniques according to the recommendations of the National Committee for Clinical Laboratory Standards.Results. Ciprofloxacin, biapenem, imipenem, cefepime and cefpirome were all highly active against most of the Enterobacteriaceae. All the ampicillin-resistant strains of Enterobacteriaceae were susceptible to piperacillinl tazobactam, MICSll values being 4/4 mgll for Klebsiella and Proteus/Providencia spp., 8/4 mg/l for Citrobacter and Serratia spp_, and 16/4 mg/l for Escherichia coli. All the agents, with the exception of ampicillin (MIC90 4 mg/l) and chloramphenicol (MIC90 4 mg/l), were highly active against the Haemophilus influenzae isolates tested. All Bacteroides fragilis strains were susceptible to piperacillinllazobaclam (MIC90 8/4 mgll), as well as 10 co-amoxiclav (MIC90 4/2 mg/I), biapenem and imipenem (MIC90 0.5 mg/l). The Pseudomonas spp. lested included strains resistant to piperacillinltazobactam, ceftazidime, biapenem, gentamicin, tobramycin and ciprofloxacin. Cefepime was the most active agent against Pseudomonas isolates, with 90% of the strains being susceptible to this agent, while biapenem was the mast active agent against the Acinetobacter isolates investigated.Conclusions. The in vitro spectrum of activity of piperacillin!tazobactam against the majority of isolates was comparable to those of the other new agents tested

Novel Approaches to the Identification of Streptococcus pneumoniae as the Cause of Community-Acquired Pneumonia

Current diagnostic tests lack sensitivity for the identification of the bacterial etiology of pneumonia. Attempts during the past 2 decades to improve sensitivity of detection of bacterial constituents in blood by use of antibody-antigen complexes and polymerase chain reaction have been disappointing. Recent data using pneumococcal conjugate vaccines as probes suggest that increased levels of both C-reactive protein and procalcitonin may be useful adjuncts to chest radiographs in the selection of patients with presumed bacterial pneumonia for inclusion in clinical trials. Among pneumococcal diagnostics currently under investigation, quantitative real-time polymerase chain reaction of respiratory secretions, as well as urinary antigen detection and pneumococcal surface adhesin A serological analysis for adults, are candidates for use in future clinical trials of antibiotic

The Anticipated Severity of a “1918-Like” Influenza Pandemic in Contemporary Populations: The Contribution of Antibacterial Interventions

Recent studies have shown that most of deaths in the 1918 influenza pandemic were caused by secondary bacterial infections, primarily pneumococcal pneumonia. Given the availability of antibiotics and pneumococcal vaccination, how will contemporary populations fare when they are next confronted with pandemic influenza due to a virus with the transmissibility and virulence of that of 1918? To address this question we use a mathematical model and computer simulations. Our model considers the epidemiology of both the influenza virus and pneumonia-causing bacteria and allows for co-infection by these two agents as well as antibiotic treatment, prophylaxis and pneumococcal vaccination. For our simulations we use influenza transmission and virulence parameters estimated from 1918 pandemic data. We explore the anticipated rates of secondary pneumococcal pneumonia and death in populations with different prevalence of pneumococcal carriage and contributions of antibiotic prophylaxis, treatment, and vaccination to these rates. Our analysis predicts that in countries with lower prevalence of pneumococcal carriage and access to antibiotics and pneumococcal conjugate vaccines, there would substantially fewer deaths due to pneumonia in contemporary populations confronted with a 1918-like virus than that observed in the 1918. Our results also predict that if the pneumococcal carriage prevalence is less than 40%, the positive effects of antibiotic prophylaxis and treatment would be manifest primarily at of level of individuals. These antibiotic interventions would have little effect on the incidence of pneumonia in the population at large. We conclude with the recommendation that pandemic preparedness plans should consider co-infection with and the prevalence of carriage of pneumococci and other bacteria responsible for pneumonia. While antibiotics and vaccines will certainly reduce the rate of individual mortality, the factor contributing most to the relatively lower anticipated lethality of a pandemic with a 1918-like influenza virus in contemporary population is the lower prevalence of pneumococcal carriage

Use of Procalcitonin and C-Reactive Protein to Evaluate Vaccine Efficacy against Pneumonia

BACKGROUND: Pneumonia remains the leading cause of death in young children. The poor specificity of chest radiographs (CXRs) to diagnose pneumococcal pneumonia may underestimate the efficacy of pneumococcal conjugate vaccine in preventing pneumococcal pneumonia. METHODS AND FINDINGS: The efficacy of nine-valent pneumococcal conjugate vaccine among children not infected with HIV (21%; 95% confidence interval, 1%–37%) increased when CXR-confirmed pneumonia was associated with serum C-reactive protein of 120 mg/l (12mg/dl) or more and procalcitonin of 5.0 ng/ml or more (64%; 95% confidence interval, 23%–83%). Similar results were observed in children infected with HIV. CONCLUSION: C-reactive protein and procalcitonin improve the specificity of CXR to diagnose pneumococcal pneumonia and may be useful for the future evaluation of the effectiveness of pneumococcal conjugate vaccine in preventing pneumococcal pneumonia