Prospective study of nosocomial colonization and infection due to Pseudomonas aeruginosa in mechanically ventilated patients (original) (raw)
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BMJ, 1983
Despite the sparsity of Pseudomonas aeruginosa in the environment colonisation and infection with this organism was found at several sites by selective culture in 20 out of 46 patients in an intensive therapy unit. Three patients developed Ps aeruginosa pneumonia. Serial serogrouping and phage typing identified multiple strains in the unit and in the same patient. Rectal carriage occurred in 16 patients but rectal strains did not subsequently appear in tracheal aspirates; strains varied in their affinity for the upper respiratory tract. Colonisation was not directly related to length of stay and was detected in 16 of those colonised within 24 hours of admission. In intubated patients, who were colonised more frequently than those not intubated, upper respiratory tract colonisation correlated strongly with low initial arterial pH values. Personnel were probably responsible for cross infection among patients when the unit was busy. Strain differences and the susceptibility of patients also influenced colonisation and infection. Elimination of major reservoirs of Ps aeruginosa and compliance with procedures to control cross infection remain essential if patients in hospital are to escape colonisation by the organism.
Anesthesiology, 2006
Background: To facilitate the decision-making process for therapy and prevention of ventilator-associated pneumonia (VAP) in patients undergoing recent antibiotic exposure, this study investigated whether the development of VAP episodes caused by Pseudomonas aeruginosa or other pathogens are related to different risk factors, thereby distinguishing two risk population for this serious complication. Methods: A 5-year retrospective case-control observational study was conducted. Cases of VAP caused by P. aeruginosa were compared with those caused by other pathogens. Univariate and multivariate analysis was performed using SPSS 11.0 software (SPSS Inc., Chicago, IL). Results: Two groups were identified: P. aeruginosa (group P) was isolated in 58 (63.7%) episodes, and 33 episodes served as controls (group C), after a median of 12 days (interquartile range, 4-28 days) and 9 days (interquartile range, 3-12.5 days) of mechanical ventilation, respectively. P. aeruginosa was identified in 34.7% of episodes with early-onset pneumonia and in 73.5% with late-onset pneumonia. In a logistic regression analysis, P. aeruginosa was independently associated with duration of stay of 5 days or longer (relative risk ؍ 3.59; 95% confidence interval, 1.04-12.35) and absence of coma (relative risk ؍ 8.36; 95% confidence interval, 2.68-26.09). Risk for pathogens different from P. aeruginosa (group C) in early-onset pneumonia associated with coma was estimated to be 87.5%. Conclusions: Risk factors in episodes under recent antibiotic treatment caused by P. aeruginosa or other microorganism are not the same, a fact that could have implications for preventive and therapeutic approaches for this infection.
Pseudomonas aeruginosa carriage, colonization, and infection in ICU patients
Intensive Care Medicine, 2007
Objective: We evaluated whether Pseudomonas aeruginosa associated nosocomial infections in our ICU originate mainly from patients' endogenous flora or from exogenous cross-transmission. Design and setting: A 6-month prospective surveillance survey was performed according to standardized protocols at the interdisciplinary ICU of the Azienda Ospedaliera Cannizzaro. Patients: The study analyzed 121 patients and focused on three different states: carriage upon admission, colonization of sterile sites, and infections during ICU stay. Results: We identified 138 P. aeruginosa isolates from 45 patients. The cumulative incidence of P. aeruginosa sustained colonization in the ICU was 29.9/100 patients, and the incidence density was 16.2/1,000 patient-days. The cumulative incidence of P. aeruginosasustained infections in the ICU was 36.7/100 patients, and the incidence density was 19.9/1,000 patient-days. The most frequent infection type was ventilator-associated pneumonia. PFGE analysis of P. aeruginosa isolates led to the identification of a major clone represented by 60.8% of isolates involving 45.9% of patients. The impact of crosstransmission, i.e., the preventable proportion of P. aeruginosa acquisition, was estimated to be at least 59.5% of all colonization or infection episodes. Acquisition of multidrug-resistant P. aeruginosa was significantly associated with crosstransmission. Conclusions: Our results suggest that the ICU personnel and environment served as reservoirs for cross-transmission and emphasize the importance of exogenous acquisition of multidrug-resistant P. aeruginosa, of reduction in antibiotic pressure, and prompt enforcement of infection control measures.
Pseudomonas aeruginosa infection in an intensive care unit
International Journal of Infection Control, 2007
P. aeruginosa is a well-known cause of hospital-acquired pneumonia (HAP) in intensive care units (ICU). We conducted an epidemiologic and molecular investigation of endemic P. aeruginosa infection in an ICU. P. aeruginosa strains isolated from hospitalized patients and environmental samples in the ICU of the National Medical Center (NMC) were collected by the hospital infection laboratory of National Center for Disease Control and Public Health, October 2005-April 2007. The antimicrobial susceptibility of the isolates in vitro was assessed by an agar disk diffusion method, as recommended by the Clinical and Laboratory Standards Institute. The antimicrobial susceptibility data were analyzed using WHONET software. Isolates resistant to cefepime, imipenem, aztreonam, ciprofloxacin, piperacillin, and gentamicin were defined as multidrug resistant (MDR). P. aeruginosa was isolated in 89 specimens obtained from 53 patients with HAP. The incidence rate of MDR P. aeruginosa infection was 15,8/100 patient admissions per year. MDR strains were common, making up 28/89 (31,5%) of all P. aeruginosa isolates in this study. In March-August 2006 there was an outbreak of HAP caused by P. aeruginosa. During the outbreak P. aeruginosa was isolated from 25 patients with HAP. Using PFGE typing, it was observed that twelve P. aeruginosa had the same genetic pattern. Environmental investigations demonstrated the presence of P. aeruginosa in the ventilation equipment. In one case, MDR P. aeruginosa was found in the microfilter of an AV machine. The most predominant etiological factor responsible for HAP in ICU of NMC was endemic P. aeruginosa.
Microbes and infection, 2002
We investigated the epidemiology of antibiotic resistance and virulence properties among Pseudomonas aeruginosa clinical isolates collected in 1999 from patients hospitalized in the intensive care units of the centre hospitalier d'Orléans, in France. We compared the totality of the strains from mechanically ventilated patients with pneumonia (33 non-duplicate isolates, group 1) to 15 randomly chosen, imipenemresistant, extra-respiratory tract isolates, collected from non-infected patients hospitalized in the same units (group 2). The isolates were serotyped, typed by random amplified polymorphic DNA (RAPD), and screened for their pneumocyte cell adherence, cytotoxicity, and antibiotic resistance. A total of 35 RAPD profiles were found, and only two profiles were encountered in both groups, demonstrating a high genetic diversity. 84.8% of the group 1 and 93.3% of the group 2 isolates adhered to A549 cells. Three non-exclusive adhesive patterns were observed: a diffuse adhesion in 38 isolates, a localized adhesion in 14 isolates, and an aggregative adhesion in seven isolates. 78.8% of the group 1 and 93.3% of the group 2 isolates were cytotoxic. Considering all 48 isolates, there was a strong and statistically significant correlation between cytotoxicity and adherence. Among the three dominant serotypes, O:12 isolates were in majority avirulent, but the great majority of O:1 and all the O:11 isolates were found adherent and cytotoxic. Gentamicin was the least active antibiotic for both groups, and ceftazidime was the most active antibiotic for group 1 and amikacin for group 2. The penicillinase production phenotype was significantly correlated with a decrease in P. aeruginosa virulence.
Journal of Hospital Infection, 2003
Because of a high prevalence of Pseudomonas aeruginosa infections, we conducted an epidemiological study to assess the need for systematic surveillance, as well as the value of applying barrier precautions to P. aeruginosa carriers. From July 1997 to February 1998, we conducted a prospective cohort study in an 18bed medical intensive care unit (ICU), which is part of the infectious diseases department in a 1200-bed tertiary-care teaching hospital. Rectal and oropharyngeal swabs were obtained on admission and twice weekly. Acquired strains were genotypically characterized by pulsed-field gel electrophoresis (PFGE). A risk factor analysis for carriage, colonization and infection was performed. Among 269 eligible patients, 116 (43%) were P. aeruginosa carriers, with 46 (17%) detected on admission and 70 (26%) who acquired carriage during their stay in ICU. Among these 70 patients, 29 became colonized (N 13) or developed infection (N 16). Conversely, in the 121 patients who remained free of carriage, no colonization or infection were detected. Genotyping analysis using PFGE was performed for 81/85 (95%) acquired strains in 67 patients. The same genotype I was observed for 58/81 (70%) of these strains issued from 47 patients, and a distinct genotype II affected two other patients (three strains). The last 20 strains were not genetically related. In a multivariate model, mechanical ventilation was associated with the acquisition of P. aeruginosa carriage. Antibiotics ineffective against P. aeruginosa significantly increased the risk of colonization or infection in ICU. Although several recent studies concluded that endogenous sources account for the majority of P. aeruginosa colonizations or infections, we conclude that epidemiology may vary according to the ICU, and that cross-colonization (i.e., exogenous source) may occur and warrant reinforced barrier precautions.
Microbes and Infection, 2002
We investigated the epidemiology of antibiotic resistance and virulence properties among Pseudomonas aeruginosa clinical isolates collected in 1999 from patients hospitalized in the intensive care units of the centre hospitalier d'Orléans, in France. We compared the totality of the strains from mechanically ventilated patients with pneumonia (33 non-duplicate isolates, group 1) to 15 randomly chosen, imipenemresistant, extra-respiratory tract isolates, collected from non-infected patients hospitalized in the same units (group 2). The isolates were serotyped, typed by random amplified polymorphic DNA (RAPD), and screened for their pneumocyte cell adherence, cytotoxicity, and antibiotic resistance. A total of 35 RAPD profiles were found, and only two profiles were encountered in both groups, demonstrating a high genetic diversity. 84.8% of the group 1 and 93.3% of the group 2 isolates adhered to A549 cells. Three non-exclusive adhesive patterns were observed: a diffuse adhesion in 38 isolates, a localized adhesion in 14 isolates, and an aggregative adhesion in seven isolates. 78.8% of the group 1 and 93.3% of the group 2 isolates were cytotoxic. Considering all 48 isolates, there was a strong and statistically significant correlation between cytotoxicity and adherence. Among the three dominant serotypes, O:12 isolates were in majority avirulent, but the great majority of O:1 and all the O:11 isolates were found adherent and cytotoxic. Gentamicin was the least active antibiotic for both groups, and ceftazidime was the most active antibiotic for group 1 and amikacin for group 2. The penicillinase production phenotype was significantly correlated with a decrease in P. aeruginosa virulence.
Revista Brasileira de terapia intensiva
To phenotypically evaluate biofilm production by Pseudomonas aeruginosa clinically isolated from patients with ventilator-associated pneumonia. Twenty clinical isolates of P. aeruginosa were analyzed, 19 of which were from clinical samples of tracheal aspirate, and one was from a bronchoalveolar lavage sample. The evaluation of the capacity of P. aeruginosa to produce biofilm was verified using two techniques, one qualitative and the other quantitative. The qualitative technique showed that only 15% of the isolates were considered biofilm producers, while the quantitative technique showed that 75% of the isolates were biofilm producers. The biofilm isolates presented the following susceptibility profile: 53.3% were multidrug-resistant, and 46.7% were multidrug-sensitive. The quantitative technique was more effective than the qualitative technique for the detection of biofilm production. For the bacterial population analyzed, biofilm production was independent of the susceptibility p...