The clinical significance of pneumonia in patients with respiratory specimens harbouring multidrug-resistant Pseudomonas aeruginosa: a 5-year retrospective study following 5667 patients in four general ICUs
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Pseudomonas aeruginosa is the leading cause of pneumonia in intensive care units (ICUs), with multidrug-resistant (MDR) strains posing a serious threat. The aim of this study was to assess the clinical relevance of MDR Pseudomonas isolates in respiratory clinical specimens. A 5-year retrospective observational study in four medical-surgical ICUs from a referral hospital was carried out. Of 5667 adults admitted to the ICU, 69 had MDR-PA in respiratory samples: 31 were identified as having pneumonia (HAP/VAP): 21 ventilator-associated pneumonia (VAP) and ten hospital-acquired pneumonia (HAP). Twenty-one (67.7%) adults with MDR-PA HAP/VAP died after a median of 4 days (18 of the 21 deaths within 8 days), compared with one (2.6%) without pneumonia at day 8. In a Cox proportional regression model, MDR-PA pneumonia was an independent variable [adjusted hazard ratio (aHR) 5.92] associated with 30-day ICU mortality. Most strains (85.1%) were susceptible to amikacin and colistin. Resistance to beta-lactams (third-generation cephalosporins and piperacillin–tazobactam) ranged from 44.1% to 45.3%. Meropenem showed poor overall activity (MIC[50/90] 16/32 mg/dL), with 47.0% having a minimum inhibitory concentration (MIC) breakpoint >8 mg/L. Twenty-four (77.4%) HAP/VAP episodes received inappropriate empirical therapy. Although empirical combination therapy was associated with less inappropriate therapy than monotherapy (16.7% vs. 88.3%, p < 0.01), there was no difference in survival (30% vs. 33.3%, p = 0.8). Pneumonia was identified in one-third of adult ICU patients harbouring MDR-PA in respiratory clinical specimens. These patients have a 6-fold risk of (early) death compared to ventilator-associated tracheobronchitis (VAT) and respiratory colonisation. New antibiotics and adjuvant therapies are urgently needed to prevent and treat MDR-PA HAP/VAP.
Part of the statistical analysis was carried out in the Statistical and Bioinformatics Unit (UEB) of the Vall d’Hebron Hospital Research Institute (VHIR). We would like to thank Michael Maudsley and Dr. David Thompson for their professional writing services.
Compliance with ethical standards
This study was supported in part by Beca Rio Hortega—Instituto de Salud Carlos III [CM 14/00212], Beca FIS [PI12/02903], Beca SEPAR [155/2015], Beca Agaur [2014-AGAUR-278], CIBERES-PCI Pneumonia and Fondos FEDER.
Conflict of interest
J.R. is on the speaker bureau for Cubist, AstraZeneca, MedImmune, Kenta, Pfizer, Genentech and Paratek. The other authors have no conflicts of interest to report.
The study was approved by the local institutional review board, with the identification ‘PR_AG_247-2012’.
Informed consent was waived due to the observational nature of the study.
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