Acquisition of Pseudomonas aeruginosa and its resistance phenotypes in critically ill medical patients: role of colonization pressure and antibiotic exposure

Abstract

IntroductionThe objective of this work was to investigate the risk factors for the acquisition of Pseudomonas aeruginosa and its resistance phenotypes in critically ill patients, taking into account colonization pressure.MethodsWe conducted a prospective cohort study in an 8-bed medical intensive care unit during a 35-month period. Nasopharyngeal and rectal swabs and respiratory secretions were obtained within 48 hours of admission and thrice weekly thereafter. During the study, a policy of consecutive mixing and cycling periods of three classes of antipseudomonal antibiotics was followed in the unit.ResultsOf 850 patients admitted for ≥3 days, 751 (88.3%) received an antibiotic, 562 of which (66.1%) were antipseudomonal antibiotics. A total of 68 patients (8%) carried P. aeruginosa upon admission, and among the remaining 782, 104 (13%) acquired at least one strain of P. aeruginosa during their stay. Multivariate analysis selected shock (odds ratio (OR) =2.1; 95% confidence interval (CI), 1.2 to 3.7), intubation (OR =3.6; 95% CI, 1.7 to 7.5), enteral nutrition (OR =3.6; 95% CI, 1.8 to 7.6), parenteral nutrition (OR =3.9; 95% CI, 1.6 to 9.6), tracheostomy (OR =4.4; 95% CI, 2.3 to 8.3) and colonization pressure >0.43 (OR =4; 95% CI, 1.2 to 5) as independently associated with the acquisition of P. aeruginosa, whereas exposure to fluoroquinolones for >3 days (OR =0.4; 95% CI, 0.2 to 0.8) was protective. In the whole series, prior exposure to carbapenems was independently associated with carbapenem resistance, and prior amikacin use predicted piperacillin-tazobactam, fluoroquinolone and multiple-drug resistance.ConclusionsIn critical care settings with a high rate of antibiotic use, colonization pressure and non-antibiotic exposures may be the crucial factors for P. aeruginosa acquisition, whereas fluoroquinolones may actually decrease its likelihood. For the acquisition of strains resistant to piperacillin-tazobactam, fluoroquinolones and multiple drugs, exposure to amikacin may be more relevant than previously recognized.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-015-0916-7) contains supplementary material, which is available to authorized users.

Risk factors for acquisition of carbapenem-resistance during treatment with carbapenem in the intensive care unit: a prospective study

“…No deaths of patients included in our study are related to the impossibility of antibiotic treatment by multidrug resistance. Also, in contrast to other studies, prior exposure to other antibiotics, including tazocillin or aminoglycoside, was not correlated with risk of carbapenem resistance [19][20][21]. As a result of the current guidelines, carbapenems are rarely used as the first-line antibiotic; hence a large number of patients will have received therapy with other antibiotics [11,13].…”

“…Ours is one of the few prospective studies focusing on risk factors for development of bacterial resistance to carbapenem. Epidemiological data on the acquisition of carbapenem resistance have mainly been based on retrospective case-control studies [16][17][18] and previous prospective studies [19,20] have used different designs. Inclusion criteria were only admission to an ICU, whereas we choose initiation of carbapenem therapy.…”

Comparative testing of disinfectant efficacy on planktonic bacteria and bacterial biofilms using a new assay based on kinetic analysis of metabolic activity

“…; Cobos‐Trigueros et al . ). These organisms have adapted to the hospital environment and have developed resistances against disinfectants and antibiotics.…”

“…The organisms we chose for validation of our method were selected clinical isolates of multidrug-resistant organisms (MDROs), ensuring a high relevance of the results to real-world disinfection. In the hospital setting, MDROs are particularly relevant for infection prevention and control measures and are leading causes of nosocomial infections (Tacconelli et al 2008;Cobos-Trigueros et al 2015). These organisms have adapted to the hospital environment and have developed resistances against disinfectants and antibiotics.…”

Predictors of Outcomes in Patients with Prolonged Weaning with Focus on Respiratory Tract Pathogens and Infection

“…Within antibiotic classes, administration of piperacillin-tazobactam and use of amikacin were reported to be positively associated with acquisition of P. aeruginosa , whereas use of quinolones and antipseudomonal cephalosporins was protective [23]. Finally, environmental risk factors for P. aeruginosa acquisition are potentially relevant, with ICU personnel and environment serving as reservoirs for cross-transmission [19, 20, 22, 24]. In weaning patients, all these risk factors are frequently present.…”