Impact of carbapenem administration on systemic endotoxemia in patients with severe sepsis and Gram-negative bacteremia

Imipenem resistance of Pseudomonas in pneumonia: a systematic literature review

Background

Pneumonia, and particularly nosocomial (NP) and ventilator-associated pneumonias (VAP), results in high morbidity and costs. NPs in particular are likely to be caused by Pseudomonas aeruginosa (PA), ~20% of which in observational studies are resistant to imipenem. We sought to identify the burden of PA imipenem resistance in pneumonia.

Methods

We conducted a systematic literature review of randomized controlled trials (RCT) of imipenem treatment for pneumonia published in English between 1993 and 2008. We extracted study, population and treatment characteristics, and proportions caused by PA. Endpoints of interest were: PA resistance to initial antimicrobial treatment, clinical success, microbiologic eradication and on-treatment emergence of resistance of PA.

Results

Of the 46 studies identified, 20 (N = 4,310) included patients with pneumonia (imipenem 1,667, PA 251; comparator 1,661, PA 270). Seven were double blind, and 7 included US data. Comparator arms included a β-lactam (17, [penicillin 6, carbapenem 4, cephalosporin 7, monobactam 1]), aminoglycoside 2, vancomycin 1, and a fluoroquinolone 5; 5 employed double coverage. Thirteen focused exclusively on pneumonia and 7 included pneumonia and other diagnoses. Initial resistance was present in 14.6% (range 4.2-24.0%) of PA isolates in imipenem and 2.5% (range 0.0-7.4%) in comparator groups. Pooled clinical success rates for PA were 45.2% (range 0.0-72.0%) for imipenem and 74.9% (range 0.0-100.0%) for comparator regimens. Microbiologic eradication was achieved in 47.6% (range 0.0%-100.0%) of isolates in the imipenem and 52.8% (range 0.0%-100.0%) in the comparator groups. Resistance emerged in 38.7% (range 5.6-77.8%) PA isolates in imipenem and 21.9% (range 4.8-56.5%) in comparator groups.

Conclusions

In the 15 years of RCTs of imipenem for pneumonia, PA imipenem resistance rates are high, and PA clinical success and microbiologic eradication rates are directionally lower for imipenem than for comparators. Conversely, initial and treatment-emergent resistance is more likely with the imipenem than the comparator regimens.

Sepsis and septic shock: selection of empiric antimicrobial therapy

This article is a brief overview of empiric antibiotic selection for sepsis and septic shock. The article includes a differential diagnosis of the mimics of sepsis and stresses a strategy for avoiding problems associated with antibiotic resistance. Although early appropriate empiric therapy is the cornerstone of sepsis and septic shock therapy, nonantibiotic interventions are critical as well. In patients with septic shock, adequate and effective early volume replacement is essential. Early surgical intervention is critical in controlling and eliminating the septic focus if sepsis is related to perforation of a viscus (eg, the colon); obstruction of the biliary, gastrointestinal, or urinary tract; or presence of an abscess that requires drainage. If device-related infection is the cause of sepsis, device removal is essential. Empiric monotherapy for sepsis and septic shock is preferred. Multiple-drug therapy is more expensive, has an increased potential for drug-drug interactions, has a higher likelihood of side effects, and does not decrease the resistance potential of the antibiotics being used. For these reasons, early empiric monotherapy is optimal and de-escalation is not necessary if initial mono therapy was wisely selected.