New Delhi metallo-β-lactamase-producing isolates among late-onset VAP patients: multidrug-resistant pathogen and poor outcome.

BACKGROUND

spp. are increasingly important microbes involved in late-onset ventilator-associated pneumonia (VAP).

PURPOSE

The aims of this study were to determine the prevalence of New Delhi metallo-β-lactamase (MβL) (NDM-1)-producing spp. among late-onset VAP patients in different intensive care units (ICUs) of Menoufia and Kasr Al Ainy University Hospitals, to investigate the possible risk factors contributing to the acquisition of NDM-1-producing infection, and to correlate between antimicrobial resistance pattern and therapeutic efficacy as well as clinical outcomes of these patients.

MATERIALS AND METHODS

Sixty-four isolates were collected from mechanically ventilated patients with suspected late-onset VAP and subjected to antimicrobial susceptibility testing. The modified Hodge test (MHT) and combined disk tests (CDT) were applied for NDM-1 MβL detection. isolates with phenotypically confirmed MβLs production were subjected to a PCR assay to verify the presence of NDM-1 gene. The most obvious risk factors for acquisition of carbapenem resistance in VAP patients and treatment outcomes were also analyzed.

RESULTS

Out of 64 isolates, 42 (65.6%) proved to be NDM-1 positive. The sensitivity and specificity of MHT were 52.38% and 41.67%, while for CDT they were 92.86% and 83.33%, respectively. isolates showed high susceptibility to colistin (85.7%). The clinical response was better among VAP patients who received combined carbapenem plus colistin therapy than those who received colistin alone. Relapse of infection was detected in 12.5% (8/64) of VAP cases. The reported mortality reached 46.8% (30/64) of which 27 (64.3%) were infected with NDM-1-positive isolates. Prolonged duration of mechanical ventilation, longer hospital and ICU stays, and prior exposure to antibiotic therapy were by far the most important factors predisposing to carbapenem resistance among VAP patients.

CONCLUSION

A worldwide spread of spp. expressing carbapenemases represents a significant threat to the medical community. The current study addressed the high prevalence of NDM-1-producing isolates among late-onset VAP patients.