Risk factors for nosocomial imipenem-resistant Acinetobacter baumannii infections

Clinico-epidemiological nature and antibiotic susceptibility profile of Acinetobacter species

Objectives:Acinetobacter spp. has emerged as an important opportunistic pathogen responsible for nosocomial infections in many health-care settings worldwide. The study describes the clinico-epidemiology and antimicrobial susceptibility of Acinetobacter spp. in a tertiary health-care institution.

Methodology: Acinetobacter spp. were isolated from 141 specimens of the patients who reported to Universiti Kebangsaan Medical Centre (UKMMC). The sources of specimens were wound, skin and soft tissue, respiratory and urinary tract from patients in various wards. Clinio-epidemiological features of patients infected with Acinetobacter spp. were recorded. Standard bacteriological techniques with API 20NE kits and disk diffusion method were followed for identification and antibiotic sensitivity of the organisms.

Results: One hundred and forty one patients with positive culture for Acinetobacter spp. were identified. Soft tissue/wound and respiratory tract were among the commonest sites of Acinetobacter spp. isolation. The isolates were most frequently obtained from ICU. All isolates were multi-drug resistant and had a resistance rate of more than 70% to most antibiotics, except polymyxin B.

Conclusion: High prevalence of multi-drug resistance Acinetobacter spp. provides essential information on judicious antibiotic selection for empirical therapy in our health-care institution.

Risk factors for acquisition of multidrug-resistant Acinetobacter baumannii among cancer patients

BACKGROUND

Data regarding multidrug-resistant (MDR) Acinetobacter baumannii infections among cancer patients are limited.

METHODS

We conducted a case-control study to investigate the risk factors for acquisition of MDR A baumannii and the outcomes among cancer patients. Cases were inpatients with malignancy who had MDR A baumannii from any cultures between 2008 and 2011. Controls were inpatients with malignancy but no MDR A baumannii.

RESULTS

A total of 31 case patients were matched with 62 control patients. Hematologic malignancy (P = .036), need for dialysis (P = .01), admission for other reasons except elective surgery (P = .03), transfer from other health care facilities (P = .02), prolonged intensive care unit stay (P = .004), mechanical ventilation (P < .001), pressor use (P = .001), tube feeding (P < .001), transfusion (P = .009), and prior antimicrobial use (P < .001) were identified as significant risk factors in univariate analysis. Need for dialysis (odds ratio [OR], 18.23; P = .04) and prolonged intensive care unit stay (OR, 19.28; P = .01) remained significant in multivariate analysis. Lengths of stay were 28 days for the case patients and 10 days for the control patients (P = .001). The 90-day mortality rates were 41.9% and 29.0%, respectively (P = .20).

CONCLUSIONS

Acquisition of MDR A baumannii among cancer patients appears to be associated with general nosocomial infection risk factors rather than underlying malignancies.

Carbapenem-resistant Acinetobacter ventilator-associated pneumonia: Clinical characteristics and outcome

Objective:

To study the clinical characteristics and 28-days mortality in patients with ventilator-associated pneumonia (VAP) due to carbapenem-resistant Acinetobacter (CRA).

Design:

Retrospective, observational, cohort study.

Setting:

Intensive care unit (ICU) of a university hospital.

Materials and Methods:

Microbiologically confirmed VAP due to CRA infection.

Intervention:

None.

Results:

Out of 87 patients with VAP due to CRA, 60 (69%) were male; whose median age was 51 years; 73 (84%) patients were medical; 26 (30%) had history of hospitalization in last 3 months; median acute physiology and chronic health evaluation (APACHE) II was 15 and median SOFA 9 at admission; primary reason for ICU admission was respiratory failure (34%); 46 (53%) patients had more than 2 organ failure at ICU admission; median length of ICU stay was 19 days; 66 (76%) patients need vasoactive agents during ICU stay, whereas 55 (63%) patients had renal failure; median duration of mechanical ventilation was 17 days; 22 (25%) patients had acute respiratory distress syndrome (ARDS) during ICU stay; 72 (83%) patients had exposure to carbapenem before inclusion in the study; 33 (38%) patients had same organism at other sites. In the follow-up, 47 (54%) patient survived at 28 days after having VAP; whereas only 40 (46%) patients were discharged from the hospital.

Conclusions:

CRA-VAP has high crude mortality. Advanced age; severity of illness and presence of pneumonia at ICU admission; and presence of shock, ARDS and renal failure have impact on outcome in these patients.

[Lower respiratory tract infections related to Stenotrophomonas maltophilia and Acinetobacter baumannii]

Stenotrophomonas maltophilia and Acinetobacter baumannii are both non-fermenting ubiquitous Gram-negative bacilli. The incidence of lower respiratory tract infections related to these microorganisms is increasing, especially in intensive care units. Their capacity to acquire resistance against several antimicrobials is challenging for clinicians and microbiologists. Despite their low virulence, these pathogens are responsible for colonization and infection in patients with comorbidities, immunosuppression, and critically ill patients. S. maltophilia and A. baumannii are mainly identified in nosocomial infections: ventilator-associated pneumonia, bacteremia and surgical wound infection. Infections related to these microorganism are associated with high mortality and morbidity. Trimethoprime-sulfamethoxazole and carbapenem are the first line treatment for infections related to S. maltophilia and A. baumannii respectively. However, the increasing rate of resistance against these agents results in difficulties in treating patients with infections related to these pathogens. New antimicrobial agents and further randomized studies are needed to improve the treatment of these infections. Prevention of spared of these multidrug-resistant bacteria is mandatory, including hand-hygiene, environment cleaning, and limited usage of large spectrum antibiotics.

Antimicrobial use, incidence, etiology and resistance patterns in bacteria causing ventilator-associated pneumonia in a clinical-surgical intensive care unit

INTRODUCTION

Antimicrobial resistance is an increasing threat in hospitalized patients, and inappropriate empirical antimicrobial therapy is known to adversely affect outcomes in ventilator-associated pneumonia (VAP). The aim of this study was to evaluate antimicrobial usage, incidence, etiology, and antimicrobial resistance trends for prominent nosocomial pathogens causing ventilator-associated pneumonia in a clinical-surgical intensive care unit (ICU).

METHODS

Gram-negative bacilli and Staphylococcus aureus causing VAP, as well as their antimicrobial resistance patterns and data on consumption (defined daily dose [DDD] per 1,000 patient days) of glycopeptides, extended-spectrum cephalosporins, and carbapenems in the unit were evaluated in two different periods (A and B).

RESULTS

Antimicrobial use was high, mainly of broad-spectrum cephalosporins, with a significant increase in the consumption of glycopeptides (p < 0.0001) and carbapenems (p < 0.007) in period B. For Acinetobacter baumannii and members of the Enterobacteriaceae family, 5.27- and 3.06-fold increases in VAPs, respectively, were noted, and a significant increase in resistance rates was found for imipenem-resistant A. baumannii (p = 0.003) and third-generation cephalosporins-resistant Enterobacteriaceae (p = 0.01) isolates in this same period.

CONCLUSIONS

Our results suggest that there is a link between antibiotics usage at institutional levels and resistant bacteria. The use of carbapenems was related to the high rate of resistance in A. baumannii and therefore a high consumption of imipenem/meropenem could play a major role in selective pressure exerted by antibiotics in A. baumannii strains.

Clinical significance of multidrug-resistant Acinetobacter baumannii isolated from central venous catheter tip cultures in patients without concomitant bacteremia

BACKGROUND

The purpose of this study was to examine the clinical implications of a positive central venous catheter (CVC) tip culture with multidrug-resistant Acinetobacter baumannii (MRAB) in patients without concurrent bacteremia.

METHODS

This retrospective, multicenter study was conducted in 9 teaching hospitals in the Republic of Korea from May 2008 to April 2012. Study subjects included adult patients (aged ≥ 18 y) who yielded an MRAB-positive CVC tip culture without concurrent MRAB bacteremia. All patients were observed for the development of subsequent MRAB bacteremia for 6 months after CVC removal. Multivariable Firth logistic regression analysis was performed to determine predictors independently associated with subsequent MRAB bacteremia.

RESULTS

During the study period, subsequent MRAB bacteremia was observed in 18.8% of patients (21/112). Of the 112 patients, 23 (20.5%) did not show systemic inflammatory response syndrome (SIRS). None of the 23 patients without SIRS presented with subsequent MRAB bacteremia. Multivariable logistic regression analysis showed that prior administration of carbapenems (odds ratio (OR) 7.04, 95% confidence interval (CI) 1.43-34.77) or corticosteroids (OR 6.67, 95% CI 1.19-37.44), and C-reactive protein ≥ 40 mg/l (OR 18.11, 95% CI 2.22-148.07) were positive predictive factors. Prior acquisition of MRAB at a site other than the catheter (OR 0.10, 95% CI 0.03-0.39) was a negative predictive factor for developing MRAB bacteremia.

CONCLUSIONS

Our results suggest that patients with a CVC tip colonized with MRAB should be closely monitored for signs and symptoms of subsequent MRAB bacteremia.

A bronchofiberoscopy-associated outbreak of multidrug-resistant Acinetobacter baumannii in an intensive care unit in Beijing, China

Background

Bronchofiberscopy, a widely used procedure for the diagnosis of various pulmonary diseases within intensive care units, has a history of association with nosocomial infections. Between September and November 2009, an outbreak caused by multidrug-resistant Acinetobacter baumannii (MDR-Ab) was observed in the intensive care unit of a tertiary care hospital in Beijing, China. This study is aimed to describe the course and control of this outbreak and investigate the related risk factors.

Methods

Clinical and environmental sampling, genotyping with repetitive extragenic palindromic polymerase chain reaction (REP-PCR), and case–control risk factor analysis were performed in the current study.

Results

During the epidemic period, 12 patients were infected or colonized with MDR-Ab. Sixteen (72.7%) of twenty-two MDR-Ab isolates from the 12 patients and 22 (84.6%) of 26 MDR-Ab isolates from the bronchofiberscope and the healthcare-associated environment were clustered significantly into a major clone (outbreak MDR-Ab strain) by REP-PCR typing. Seven patients carrying the outbreak MDR-Ab strain were defined as the cases. Six of the seven cases (83%) received bronchofiberscopy versus four of the 19 controls (21%) (odds ratio, 22.5; 95% confidence interval, 2.07–244.84; P = 0.005). Several potential administrative and technical problems existed in bronchofiberscope reprocessing.

Conclusions

Bronchofiberscopy was associated with this MDR-Ab outbreak. Infection control precautions including appropriate bronchofiberscope reprocessing and environmental decontamination should be strengthened.

Risk factors and outcomes in patients with carbapenem-resistant Acinetobacter infection

INTRODUCTION

Acinetobacter spp. are important pathogens increasingly reported as the cause of outbreaks of nosocomial infections. The aim of our study was to identify the risk factors and assess their influence on outcomes in patients with infections caused by carbapenem-resistant Acinetobacter spp.

METHODS

A retrospective data analysis was performed to evaluate risk factors and mortality in patients with Acinetobacter spp. infections. Methods used for the statistical analysis were the Student's t-test, Chi-square test, and multivariate analysis; p < 0.05 was considered statistically significant.

RESULTS

A total of 99 patients with an Acinetobacter spp. infection were identified. Comparing patients with carbapenem-sensitive and carbapenem-resistant Acinetobacter spp. infection, significant differences were found in the mean length of intensive care unit stay (4.17 ± 3.61 vs 7.92 ± 6.74 days, p = 0.038) and mechanical ventilation (3.25 ± 2.61 and 7.07 ± 5.79 days, p = 0.009). The previous use of carbapenems (odds ratio (OR) 10.1, 95% confidence interval (CI) 1.16-87.20) and fluoroquinolones (OR 3.6, 95% CI 1.13-11.51) was independently associated with resistance to carbapenems. Of the Acinetobacter spp. strains, 94.9% (n = 94) were resistant to piperacillin-tazobactam, 88.9% (n = 88) to ceftazidime, 85.9% (n = 85) to ciprofloxacin, 83.8% (n = 83) to gentamicin, 79.8 (n = 79) to amikacin, and 48.5% (n = 48) to cefepime.

CONCLUSIONS

Intensive care unit stay before infection and source of infection in the respiratory tract were independently associated with patient mortality. Resistance to carbapenems had no impact on mortality rates. Carbapenem-resistant Acinetobacter spp. isolates had high resistance rates to other antimicrobial drugs.

Risk factors for carbapenem non-susceptibility and mortality in Acinetobacter baumannii bacteremia in children

OBJECTIVE

To examine the risk factors of carbapenem non-susceptibility and mortality among children with Acinetobacter baumannii bacteremia.

METHODS

A retrospective chart review was conducted of 180 cases with A. baumannii bacteremia.

RESULTS

The 30-day mortality risk of A. baumannii bacteremia was 26.1%. Carbapenem-non-susceptible A. baumannii was identified in 51.7% of cases. Logistic regression analysis indicated that prematurity, use of mechanical ventilation, and prior exposure to carbapenem antibiotics were independently associated with carbapenem-non-susceptible A. baumannii bacteremia, with adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of 3.36 (1.17-9.65), 5.59 (2.24-13.97), and 2.97 (1.01-8.77), respectively. Further, carbapenem non-susceptibility, cancer-related neutropenia, organ dysfunction, admission to the intensive care unit, catheter-related bacteremia, and treatment with sulbactam-containing regimens were associated with mortality with aORs and 95% CIs of 4.76 (1.58-14.32), 4.54 (1.09-18.79), 25.95 (5.13-131.33), 3.53 (1.29-9.71), 0.25 (0.084-0.72), and 0.14 (0.046-0.45), respectively.

CONCLUSIONS

The majority of A. baumannii bacteremia was caused by carbapenem-non-susceptible strains with a high mortality rate. Carbapenem non-susceptibility, cancer-related neutropenia, the presence of organ dysfunction, and admission to an intensive care unit were associated with an increased mortality risk, whereas catheter-related bacteremia and treatment with a sulbactam-containing regimen were associated with decreased mortality among children with A. baumannii bacteremia.

Risk factors for occurrence and 30-day mortality for carbapenem-resistant Acinetobacter baumannii bacteremia in an intensive care unit

To assess the risk factors for carbapenem-resistant Acinetobacter baumannii (CRAB) bacteremia and for 30-day mortality in patients with CRAB bacteremia in the intensive care unit (ICU), we conducted a retrospective study in the ICU at Severance Hospital in Korea from January 2008 to December 2009. Patients who acquired CRAB bacteremia in the ICU were enrolled as the case group and patients whose specimens of blood culture, sputum/endotracheal aspirate and urine revealed no AB were enrolled as controls. The case group comprised 106 patients and 205 patients were included as controls. Risk factors independently associated with CRAB bacteremia included prior chemotherapy or radiotherapy treatment (Odds ratio [OR], 3.6; P = 0.003), recent central venous catheter insertion (OR, 5.7; P < 0.001) or abdominal drainage insertion (OR, 21.9; P = 0.004), the number of antibiotics treated with (OR, 1.3; P = 0.016), and respiratory failure in the ICU (OR, 2.5; P = 0.035). The 30-day mortality was 79.8%. Renal failure during ICU stay was independently associated with 30-day mortality (OR, 3.7; P = 0.047). It is important to minimize invasive procedures, and to restrict excessive use of antibiotics, especially in immunocompromised patients, in order to prevent the development of CRAB bacteremia. Greater concern for CRAB bacteremia patients is needed when renal failure develops during ICU stay.

Investigation and control of an outbreak of imipenem-resistant Acinetobacter baumannii Infection in a Pediatric Intensive Care Unit

BACKGROUND

This study investigated the clinical details and epidemiology of the imipenem-resistant Acinetobacter baumannii (IRAB) outbreak that occurred at a pediatric intensive care unit (PICU), and describes successful outcome of the implemented infection control measures.

METHODS

With the recognition of 3 clustered cases with IRAB bacteremia at the PICU of Seoul National University Children's Hospital, Korea, from August to September 2010, the following outbreak control strategies were implemented: reinforcement of hand hygiene and contact precautions, investigation of environmental contamination, disinfection of the contaminated environment and medical equipment, active surveillance culture upon PICU admission and isolation of IRAB-positive patients. The clinical and microbiological data were reviewed for A. baumannii positive cases in the PICU from April 2001 to June 2011. Multilocus sequence typing was also performed.

RESULTS

Twenty IRAB-positive cases (bacteremia in 10, pneumonia in 3 and colonizers in 7) were detected from January 2010 to February 2011. Thirteen IRAB-infected patients were all placed on a mechanical ventilator, had central venous catheters, received broad-spectrum antimicrobial treatment and had underlying diseases. Eleven (85%) IRAB-infected patients died probably due to IRAB infection. IRAB grew in 4 samples obtained from sinks and water taps from 38 environmental samples. Multilocus sequence typing analysis revealed 2 sequence types: ST138 (n=16) and its single-locus variant ST92 (n=4). Eleven weeks after the initiation of active surveillance, no further IRAB isolates were identified.

CONCLUSIONS

This study identifies the environmental source of an IRAB outbreak in a PICU and describes successful control of the outbreak with a multicomponent intervention program.

Increase of carbapenem-resistant Acinetobacter baumannii infection in acute care hospitals in Taiwan: association with hospital antimicrobial usage

Objective

Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as an important pathogen causing healthcare-associated infections (HAIs) in Taiwan. The present study is aimed to investigate the epidemiology of HAIs caused by CRAB and the association of CRAB infection and hospital usage of different antimicrobials.

Methods

Two nationwide databases in the period 2003 to 2008, the Taiwan Nosocomial Infection Surveillance System and National Health Insurance claim data, were used for analysis. A total of 13,811 healthcare-associated A. baumannii infections and antimicrobial usage data from 121 hospitals were analyzed.

Results

There was a significant increase in the proportion of number of HAIs caused by CRAB over that by all A. baumannii (CRABpAB), from 14% in 2003 to 46% in 2008 (P<0.0001). The greatest increase was in central Taiwan, from 4% in 2003 to 62% in 2008 (P<0.0001). Use of anti-pseudomonal carbapenems, but not other classes of antibiotics, was significantly correlated with the increase of CRABpAB (r = 0.86, P<0.0001).

Conclusions

We suggested that dedicated use of anti-pseudomonal carbapenems would be an important intervention to control the increase of CRABpAB.

Management of antimicrobial use in the intensive care unit

Critically ill patients admitted to the intensive care unit (ICU) are frequently treated with antimicrobials. The appropriate and judicious use of antimicrobial treatment in the ICU setting is a constant clinical challenge for healthcare staff due to the appearance and spread of new multiresistant pathogens and the need to update knowledge of factors involved in the selection of multiresistance and in the patient's clinical response. In order to optimize the efficacy of empirical antibacterial treatments and to reduce the selection of multiresistant pathogens, different strategies have been advocated, including de-escalation therapy and pre-emptive therapy as well as measurement of pharmacokinetic and pharmacodynamic (pK/pD) parameters for proper dosing adjustment. Although the theoretical arguments of all these strategies are very attractive, evidence of their effectiveness is scarce. The identification of the concentration-dependent and time-dependent activity pattern of antimicrobials allow the classification of drugs into three groups, each group with its own pK/pD characteristics, which are the basis for the identification of new forms of administration of antimicrobials to optimize their efficacy (single dose, loading dose, continuous infusion) and to decrease toxicity. The appearance of new multiresistant pathogens, such as imipenem-resistant Pseudomonas aeruginosa and/or Acinetobacter baumannii, carbapenem-resistant Gram-negative bacteria harbouring carbapenemases, and vancomycin-resistant Enterococcus spp., has determined the use of new antibacterials, the reintroduction of other drugs that have been removed in the past due to toxicity or the use of combinations with in vitro synergy. Finally, pharmacoeconomic aspects should be considered for the choice of appropriate antimicrobials in the care of critically ill patients.

Risk factors, molecular epidemiology and outcomes of ertapenem-resistant, carbapenem-susceptible Enterobacteriaceae: a case-case-control study

Background

Increasing prevalence of ertapenem-resistant, carbapenem-susceptible Enterobacteriaceae (ERE) in Singapore presents a major therapeutic problem. Our objective was to determine risk factors associated with the acquisition of ERE in hospitalized patients; to assess associated patient outcomes; and to describe the molecular characteristics of ERE.

Methods

A retrospective case-case-control study was conducted in 2009 at a tertiary care hospital. Hospitalized patients with ERE and those with ertapenem-sensitive Enterobacteriaceae (ESE) were compared with a common control group consisting of patients with no prior gram-negative infections. Risk factors analyzed included demographics; co-morbidities; instrumentation and antibiotic exposures. Two parallel multivariate logistic regression models were performed to identify independent variables associated with ERE and ESE acquisition respectively. Clinical outcomes were compared between ERE and ESE patients.

Results

Twenty-nine ERE cases, 29 ESE cases and 87 controls were analyzed. Multivariate logistic regression showed that previous hospitalization (Odds ratio [OR], 10.40; 95% confidence interval [CI], 2.19–49.20) and duration of fluoroquinolones exposure (OR, 1.18 per day increase; 95% CI, 1.05–1.34) were unique independent predictors for acquiring ERE. Duration of 4^th-generation cephalosporin exposure was found to predict for ESE acquisition (OR, 1.63 per day increase; 95% CI, 1.05–2.54). In-hospital mortality rates and clinical response rates were significantly different between ERE and ESE groups, however ERE infection was not a predictor of mortality. ERE isolates were clonally distinct. Ertapenem resistance was likely to be mediated by the presence of extended-spectrum β-lactamases or plasmid-borne AmpC in combination with impermeability due to porin loss and/or efflux pumps.

Conclusion

Prior hospitalization and duration of fluoroquinolone treatment were predictors of ERE acquisition. ERE infections were associated with higher mortality rates and poorer clinical response rates when compared to ESE infections.

Use of adherence monitors as part of a team approach to control clonal spread of multidrug-resistant Acinetobacter baumannii in a research hospital

BACKGROUND

Multidrug-resistant Acinetobacter baumannii (MDRAB) is difficult to treat and eradicate. Several reports describe isolation and environmental cleaning strategies that controlled hospital MDRAB outbreaks. Such interventions were insufficient to interrupt MDRAB transmission in 2 intensive care unit-based outbreaks in our hospital. We describe strategies that were associated with termination of MDRAB outbreaks at the National Institutes of Health Clinical Center.

METHODS

In response to MDRAB outbreaks in 2007 and 2009, we implemented multiple interventions, including stakeholder meetings, enhanced isolation precautions, active microbial surveillance, cohorting, and extensive environmental cleaning. We conducted a case-control study to analyze risk factors for acquiring MDRAB. In each outbreak, infection control adherence monitors were placed in MDRAB cohort areas to observe and correct staff infection control behavior.

RESULTS

Between May 2007 and December 2009, 63 patients acquired nosocomial MDRAB; 57 (90%) acquired 1 or more of 4 outbreak strains. Of 347 environmental cultures, only 2 grew outbreak strains of MDRAB from areas other than MDRAB patient rooms. Adherence monitors recorded 1,330 isolation room entries in 2007, of which 8% required interventions. In 2009, around-the-clock monitors recorded 4,892 staff observations, including 127 (2.6%) instances of nonadherence with precautions, requiring 68 interventions (1.4%). Physicians were responsible for more violations than other staff (58% of hand hygiene violations and 37% of violations relating to gown and glove use). Each outbreak terminated in temporal association with initiation of adherence monitoring.

CONCLUSIONS

Although labor intensive, adherence monitoring may be useful as part of a multifaceted strategy to limit nosocomial transmission of MDRAB.

Knowledge and practices regarding prevention of infections associated with central venous catheters: a survey of intensive care unit medical and nursing staff

BACKGROUND

Infections associated with central venous catheters (CVCs) are associated with considerable morbidity and mortality.

METHODS

We conducted a survey to evaluate the theoretical knowledge and practices of intensive care unit doctors and nursing staff regarding CVC-related infections.

RESULTS

A questionnaire was distributed to 345 doctors and nurses. The response rate was 71.6%. Of the responders, 84.9% worked in public hospitals, 40% had been trained in CVC-related infection issues, and 27% were familiar with the relevant Centers of Disease Control and Prevention guidelines. The mean percentage of correct answers (± standard deviation) on the 3 parts of the questionnaire were 42.9% ± 16.2%, 86.9% ± 9.5%, and 85.4% ± 7.2%. In the subset of questions referring to procedures that were doctors' exclusive responsibility, 13.6% of the doctors answered all questions correctly. Age >37 years, awareness of relevant official guidelines, working in a private hospital, and being a doctor were identified as independent variables associated with high scores in knowledge regarding the prevention of CVC-related infections. Female sex and training in infection prevention were associated with higher scores on the part evaluating adherence to specific practices regarding CVC insertion, whereas being a nurse was associated with higher scores on the part evaluating CVC maintenance.

CONCLUSION

Our findings suggest that there is a need for increased theoretical knowledge and improvement in practices regarding CVC care. Educational programs directed at doctors and nurses working in intensive care units may aid this effort.

Investigation and management of an imipenem-resistant oxa-23 Acinetobacter baumannii outbreak in an intensive care unit

OBJECTIVES

The study objectives were to describe the investigation and management of an imipenem-resistant Acinetobacter baumannii outbreak that occurred in the 15-bed ICU of a tertiary care teaching hospital (Brest, France), during the summer 2008.

PATIENTS AND METHODS

Patients harboring an imipenem-resistant A. baumannii strain were defined as case patients. We described case occurrence and steps taken to control the outbreak: contact isolation, reinforcement of hygiene procedures, unit shutdown decision, unit disinfection, and reopening. We also made a case control study and a cost analysis of the outbreak management.

RESULTS

During a 10-day period, five patients were positive for a single clone of imipenem-resistant oxa-23 A. baumannii. Four patients presented with ventilation-acquired pneumonia and one was asymptomatic. The first two patients died one day after the first swab which led to the identification of A. baumannii. No additional case was noted in the ICU or in other hospital units after deciding to close the ICU. The cost of outbreak management was estimated at 264,553 euros. The case control study identified several factors associated with infection or colonization: length of stay in the ICU, chronic respiratory disease, number of previous antibiotic classes used, duration of ventilation, prone position, echocardiography, and presence of a nasogastric tube.

CONCLUSION

This outbreak occurred during the summer period requiring the shutdown of the ICU and inducing a considerable cost. Rapid reactions of the ICU staff during the outbreak enabled to limit the epidemic.

Acinetobacter baumannii infection in patients with hematologic malignancies in intensive care unit: risk factors and impact on mortality

PURPOSE

We investigated the characteristics of Acinetobacter baumannii infection in critically ill patients with hematologic malignancies.

MATERIALS AND METHODS

The prospectively collected data of patients with hematologic malignancies admitted to a medical intensive care unit of a university hospital from 2007 through 2010 were reviewed retrospectively.

RESULTS

One hundred twenty-eight patients were included in the study, among whom 35 (27%) developed 39 A baumannii infections. Pneumonia was the most common infection site of A baumannii. Presence of neutropenia, underlying hematologic malignancy, and the disease status did not affect the acquisition of the infection. Advancing age, prior exposure to aminoglycosides, central venous catheterization, and presence of nasogastric tube were the independent risk factors for the development of A baumannii infections. The mortality rate was higher in patients with A baumannii infections compared with the ones without (P = .009). However, in multivariate analysis, low Glasgow coma scale, prior immunosuppressive treatment, neutropenia, invasive mechanical ventilation, and severe sepsis were independently associated with mortality, whereas presence of A baumannii infection was not.

CONCLUSIONS

Despite the high mortality rate in critically ill patients with hematologic malignancies, presence of A baumannii infection was not an independent risk factor for mortality.

Community-acquired carbapenem-resistant Acinetobacter baumannii urinary tract infection just after marriage in a renal transplant recipient

Urinary tract infection (UTI) is common in renal transplant recipients and may worsen allograft and patient survival. Many risk factors such as age, female gender, immunosuppression, comorbidity, deceased-donor kidney transplantation, and uretheral catheterization are involved in development of UTI. Acinetobacter baumannii has rarely been reported as a causative agent for development of UTI. Here, we present an unusual case of a renal transplant recipient who developed community-acquired carbapenem-resistent A. baumannii UTI.

Carbapenem-resistant Acinetobacter baumannii: diversity of resistant mechanisms and risk factors for infection

Carbapenem-resistant Acinetobacter baumannii (CRAB) are an increasing infectious threat in hospitals. We investigated the clinical epidemiology of CRAB infections vs. colonization in patients, and examined the mechanisms of resistance associated with elevated minimum inhibitory concentrations (MICs) for carbapenems. From January to June 2009, 75 CRAB strains were collected. CRAB infection was significantly associated with malignancy and a high APACHE II score. The most dominant resistance mechanism was ISAba1 preceding OXA-51, producing strains with overexpression of efflux pump. Strains carrying blaOXA-23-like enzymes had higher carbapenem MICs than those carrying blaOXA-51-like enzymes; however, the presence of multiple mechanisms did not result in increased resistance to carbapenems. There was no difference in the resistance mechanisms in strains from infected and colonized patients. The majority of strains were genetically diverse by DNA macrorestriction although there was evidence of clonal spread of four clusters of strains in patients.

The risks and benefits of chemical fumigation in the health care environment

Fumigation of hospital rooms with high concentrations of toxic chemicals has been proposed to reduce microbial agents on hospital surfaces and to control infections. Chemical fumigation has been used effectively in other areas, such as building decontamination after bioterrorism events, in agriculture, and in residential structures. However, even in these situations, there have been incidents where fumigants have escaped, causing illness and death to exposed workers and the public. Before expanding the use of a potentially hazardous technology in areas where there are vulnerable individuals, it is important to fully weigh benefits and risks. This article reviews the effectiveness of fumigation as a method of inactivating microbes on environmental surfaces and in reducing patient infection rates against the potential risks. Peer-reviewed literature, consensus documents, and government reports were selected for review. Studies have demonstrated that fumigation can be effective in inactivating microbes on environmental surfaces. However, the current consensus of the infection control community is that the most important source of patient infection is direct contact with health care workers or when patients auto-infect themselves. Only one peer-reviewed, before-after study, at one hospital reported a significant reduction in infection rates following chemical fumigation. The limitations of this study were such that the authors acknowledged that they could not attribute the rate reduction to the fumigation intervention. A serious concern in the peer-reviewed literature is a lack of evidence of environmental monitoring of either occupational or non-occupational exposures during fumigation. Currently, there are neither consensus documents on safe fumigation exposure levels for vulnerable bedridden patients nor sampling methods with an acceptable limit of detection for this population. Until additional peer-reviewed studies are published, demonstrating significant reductions in patient infection rates following chemical fumigation and consensus guidance on the safe exposure levels and monitoring methods, chemical fumigation in health care should be conducted only in the most stringently controlled research settings.

Nosocomial imipenem-resistant Acinetobacter baumannii infections: epidemiology and risk factors

The incidence, clinical characteristics, risk factors, antimicrobial susceptibility, and outcomes of nosocomial imipenem-resistant A. baumannii (IRAB) infections during a 5-y period (2003-2007) were retrospectively analyzed. A total of 720 patients with 925 episodes of A. baumannii infection were included in the study. A. baumannii infections were seen mostly in intensive care units. The incidence was 6.2 per 1000 admissions. The most common infections were pneumonias and bloodstream infections. Imipenem resistance among Acinetobacter strains increased significantly each y of the study (from 43.3% to 72.9%). Mortality was related to the presence of imipenem resistance, stay in intensive care unit, female gender, old age, and pneumonia. Haemodialysis, malignancy, and mechanical ventilation were significant risk factors for IRAB infections. Imipenem resistance was higher in strains isolated from patients with pneumonia. IRAB strains showed higher resistance rates to other antibiotics than imipenem-susceptible strains. The most active antimicrobial agents against A. baumannii were cefoperazone-sulbactam and netilmicin. The incidence of A. baumannii infections and imipenem resistance increased during the study period. IRAB infections should be considered in patients on mechanical ventilation and haemodialysis and in patients with malignancies.

Multidrug resistant Acinetobacter baumannii: a descriptive study in a city hospital

Background

Multidrug resistant Acinetobacter baumannii, (MRAB) is an important cause of hospital acquired infection. The purpose of this study is to determine the risk factors for MRAB in a city hospital patient population.

Methods

This study is a retrospective review of a city hospital epidemiology data base and includes 247 isolates of Acinetobacter baumannii (AB) from 164 patients. Multidrug resistant Acinetobacter baumannii was defined as resistance to more than three classes of antibiotics. Using the non-MRAB isolates as the control group, the risk factors for the acquisition of MRAB were determined.

Results

Of the 247 AB isolates 72% (177) were multidrug resistant. Fifty-eight percent (143/247) of isolates were highly resistant (resistant to imipenem, amikacin, and ampicillin-sulbactam). Of the 37 patients who died with Acinetobacter colonization/infection, 32 (86%) patients had the organism recovered from the respiratory tract. The factors which were found to be significantly associated (p ≤ 0.05) with multidrug resistance include the recovery of AB from multiple sites, mechanical ventilation, previous antibiotic exposure, and the presence of neurologic impairment. Multidrug resistant Acinetobacter was associated with significant mortality when compared with sensitive strains (p ≤ 0.01). When surgical patients (N = 75) were considered separately, mechanical ventilation and multiple isolates remained the factors significantly associated with the development of multidrug resistant Acinetobacter. Among surgical patients 46/75 (61%) grew a multidrug resistant strain of AB and 37/75 (40%) were resistant to all commonly used antibiotics including aminoglycosides, cephalosporins, carbepenems, extended spectrum penicillins, and quinolones. Thirty-five percent of the surgical patients had AB cultured from multiple sites and 57% of the Acinetobacter isolates were associated with a co-infecting organism, usually a Staphylococcus or Pseudomonas. As in medical patients, the isolation of Acinetobacter from multiple sites and the need for mechanical ventilation were significantly associated with the development of MRAB.

Conclusions

The factors significantly associated with MRAB in both the general patient population and surgical patients were mechanical ventilation and the recovery of Acinetobacter from multiple anatomic sites. Previous antibiotic use and neurologic impairment were significant factors in medical patients. Colonization or infection with MRAB is associated with increased mortality.

A multicenter study of risk factors and outcome of hospitalized patients with infections due to carbapenem-resistant Acinetobacter baumannii

BACKGROUND

Risk factors and outcome in patients who acquire nosocomial infections due to carbapenem-resistant Acinetobacter baumannii (CRAB) are rarely investigated.

METHODS

A multicenter retrospective study was conducted to analyze the clinical and microbiological data of patients with nosocomial infections due to A. baumannii in 10 hospitals around Taiwan from May 2004 to December 2006. Comparisons were made between patients with infections due to CRAB and patients with infections due to carbapenem-susceptible A. baumannii (CSAB).

RESULTS

One hundred and twenty-one patients carrying CRAB (infections, n=91) and 127 patients carrying CSAB (infections, n=97) were recruited for analysis. Compared with patients with CSAB infections, patients with CRAB infections had a longer duration of hospital stay before A. baumannii was isolated (median 48 vs. 21 days, p<0.001) and were more likely to have had exposure to a carbapenem (adjusted odds ratio (AOR) 2.57, 95% confidence interval (95% CI) 1.43-5.35; p=0.02) and an intensive care unit (ICU) stay (AOR 3.42, 95% CI 1.76-5.26; p=0.008). Risk factors associated with CRAB bacteremia included duration of hospital stay before onset of bacteremia (AOR 1.009 per 1-day longer, 95% CI 1.03-1.24; p=0.049), prior colonization with A. baumannii (AOR 3.27, 95% CI 1.99-5.93; p=0.002), and hospitalization in the ICU (AOR 6.12, 95% CI 1.58-13.68; p=0.009). Patients with CRAB bacteremia had a higher mortality rate than patients with CSAB bacteremia (46.0% vs. 28.3%, p=0.04). Multivariate analysis showed that carbapenem resistance (AOR 5.31, 95% CI 1.88-13.25; p=0.002), central venous catheterization (AOR 3.27, 95% CI 1.55-10.56; p=0.009), and ICU stay (AOR 2.56, 95% CI 1.15-8.85; p=0.04) were independent variables associated with mortality in patients with A. baumannii bacteremia.

CONCLUSIONS

Patients with CRAB infections have a higher mortality rate than those with CSAB infections. Longer hospital stay, colonization with A. baumannii, and admission to the ICU were associated with the development of CRAB bacteremia.

Carbapenem-resistant versus carbapenem-susceptible Acinetobacter baumannii bacteremia in a Greek intensive care unit: risk factors, clinical features and outcomes

BACKGROUND

There has been an increasing incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) infections in recent years. The objective of this study was to determine specific risk factors for and outcome of bacteremia due to CRAB isolates among our ICU patients with A. baumannii bacteremia.

PATIENTS AND METHODS

Among 96 patients with ICU-acquired A. baumannii bacteremia, 30 patients with CRAB were compared with the remaining 66 with carbapenem-susceptible A. baumannii (CSAB) isolates.

RESULTS

Recent ventilator-associated pneumonia (VAP) due to CRAB (OR 16.74, 95% CI 3.16-88.79, p = 0.001) and a greater number of intravascular devices (OR 3.93, 95% CI 1.9-13.0, p = 0.025) were independently associated with CRAB bacteremia acquisition. Patients with CRAB bacteremia had a lower severity of illness on admission than those with CSAB. Although, by univariate analysis, patients with CRAB were more likely to have had exposure to colistin, carbapenems and linezolid, multivariate analysis did not revealed any significant association. The mortality was not different between patients with CRAB and CSAB bacteremia (43.3 vs. 46.9%, p = 0.740). Severity of organ failure (OR 1.42, 95% CI 1.20-1.67, p = 0.001), and increased white blood cell (WBC) count (OR 1.09, 95% CI 1.01-1.19, p = 0.036), at bacteremia onset were independently associated with mortality.

CONCLUSION

VAP due to CRAB and excess use of intravascular devices are the most important risk factors for CRAB bacteremia in our ICU. Severity of organ failure and WBC count at A. baumannii bacteremia onset are independently associated with mortality.

Patterns of antimicrobial therapy in severe nosocomial infections: empiric choices, proportion of appropriate therapy, and adaptation rates--a multicentre, observational survey in critically ill patients

This prospective, observational multicentre (n=24) study investigated relationships between antimicrobial choices and rates of empiric appropriate or adequate therapy, and subsequent adaptation of therapy in 171 ICU patients with severe nosocomial infections. Appropriate antibiotic therapy was defined as in vitro susceptibility of the causative pathogen and clinical response to the agent administered. In non-microbiologically documented infections, therapy was considered adequate in the case of favourable clinical response <5 days. Patients had pneumonia (n=127; 66 ventilator-associated), intra-abdominal infection (n=23), and bloodstream infection (n=21). Predominant pathogens were Pseudomonas aeruginosa (n=29) Escherichia coli (n=26), Staphylococcus aureus (n=22), and Enterobacter aerogenes (n=21). In 49.6% of infections multidrug-resistant (MDR) bacteria were involved, mostly extended-spectrum beta-lactamase (EBSL)-producing Enterobacteriaceae and MDR non-fermenting Gram-negative bacteria. Prior antibiotic exposure and hospitalisation in a general ward prior to ICU admission were risk factors for MDR. Empiric therapy was appropriate/adequate in 63.7% of cases. Empiric schemes were classified according to coverage of (i) ESBL-producing Enterobacteriaceae and non-fermenting Gram-negative bacteria ("meropenem-based"), (ii) non-fermenting Gram-negative bacteria (schemes with an antipseudomonal agent), and (iii) first-line agents not covering ESBL-Enterobacteriaceae nor non-fermenting Gram-negative bacteria. Meropenem-based schemes allowed for significantly higher rates of appropriate/adequate therapy (p<0.001). This benefit remained when only patients without risk factors for MDR were considered (p=0.021). In 106 patients (61%) empiric therapy was modified: in 60 cases following initial inappropriate/inadequate therapy, in 46 patients in order to refine empiric therapy. In this study reflecting real-life practice, first-line use of meropenem provided significantly higher rates of the appropriate/adequate therapy, irrespective of presence of risk factors for MDR.

Carbapenem-resistant Acinetobacter baumannii infections after organ transplantation

Multi-drug resistant (MDR) gram-negative infections among solid organ transplant (SOT) recipients have long been associated with high morbidity and mortality. Acinetobacter baumannii has emerged as a potent nosocomial pathogen with the recent acquisition of resistance to broad-spectrum beta-lactams, aminoglycosides, fluoroquinolones, and most notably, carbapenems. Despite a national rise in carbapenem-resistant A. baumannii (CRAB) infections, outcomes among SOT recipients with this emerging MDR pathogen are largely unknown. This single-center cohort is the first to describe the characteristics, complications, and outcomes among abdominal organ transplant recipients with CRAB. The current study suggests that SOT patients with CRAB suffer from prolonged hospitalization, infection with other MDR organisms, allograft dysfunction and loss, and high overall infection-related mortality.

Drug treatment for multidrug-resistant Acinetobacter baumannii infections

Acinetobacter baumannii has emerged in the last decades as a major cause of healthcare-associated infections and nosocomial outbreaks. Multidrug-resistant (MDR) A. baumannii is a rapidly emerging pathogen in healthcare settings, where it causes infections that include bacteremia, pneumonia, meningitis, and urinary tract and wound infections. Antimicrobial resistance poses great limits for therapeutic options in infected patients, especially if the isolates are resistant to the carbapenems. Other therapeutic options include sulbactam, aminoglycosides, polymixyns and tigecycline. The discovery of new therapies coupled with the development of controlled clinical trial antibiotic testing combinations and the prevention of transmission of MDR Acinetobacter infection are essential to face this important hospital problem.

Ecological study of the effectiveness of isolation precautions in the management of hospitalized patients colonized or infected with Acinetobacter baumannii

OBJECTIVE

To assess the impact of isolation precautions on the incidence of patients colonized or infected with Acinetobacter baumannii (case patients) in a university hospital during the period from 1999 to 2006.

DESIGN

Ecological study.

SETTING

The Besançon University Hospital in France, a 1,200-bed acute care hospital with approximately 50,000 admissions per year.

METHODS

Using Poisson regression analysis, we evaluated a total of 350,000 patient-days to determine the annual incidence of case patients. This annual incidence was used as the outcome variable, and infection control practices, antibiotic use, and other aggregated data regarding patients' age, sex, McCabe score, and immune status were used as covariates.

RESULTS

The implementation of isolation precautions was independently and negatively associated with the incidence of patients colonized or infected with A. baumannii (relative risk, 0.50 [95% confidence interval, 0.40-0.64]; P<.001).

CONCLUSIONS

Our study suggests that the implementation of isolation precautions, in addition to standard precautions, effectively prevents the spread of A. baumannii in a hospital setting.

Risk factors and outcomes of bloodstream infections with metallo-beta-lactamase-producing Acinetobacter

The spread of Gram-negative bacilli with acquired metallo-beta-lactamase (MBL) threatens the successful treatment of major nosocomial infections. The objective of this study was to evaluate the differences in the clinical characteristics of bacteremia caused by MBL-producing Acinetobacter species and MBL non-producing isolates. Two retrospective case-control studies were conducted using data on patients with Acinetobacter bacteremia, who were admitted between January 2001 and December 2005 at a 1500-bed, tertiary-care teaching hospital. Case group 1 (n=27) included patients from whom imipenem-resistant Acinetobacter was isolated in blood culture, and case group 2 (n=7) consisted of those patients from group 1 who yielded MBL-producing isolates. The control group (n=41) included patients from whom carbapenem-susceptible Acinetobacter isolates were isolated in blood culture. Multivariate analysis revealed that the independent risk factors for imipenem-resistant Acinetobacter bacteremia were neutropenia and prolonged use of carbapenem. The independent risk factors for MBL-producing Acinetobacter bacteremia were neutropenia and prolonged use of cephalosporins. The results of this study suggest that a prolonged use of cephalosporins may be associated with MBL-producing Acinetobacter bacteremia.