Baumannii Acquisition Research Articles

A multilayered infection control intervention on carbapenem-resistant Acinetobacter baumannii acquisition: An interrupted time series

Carbapenem-resistant Acinetobacter baumannii (CRAB) causes life-threating hospital-acquired. Due to a limited number of Intensive-Care-Unit (ICU) beds, these patients are often treated in high-dependency (HD) non-ICUs within internal-medicine wards (IMW) in Israel. We aimed to assess the effectiveness of a multilayered infection-control intervention on CRAB infection rate in IMWs, especially in its HD non-ICUs with ongoing CRAB transmission. A quasi-experimental, before-and-after, interrupted time-series study with control outcomes. We conducted a multilayered intervention over 3.5years, which included 4 phases: (1) Pre intervention; (2) Interventionintroduction: introduced enhanced environment cleaning; (3) Intervention phase 1: introduced active surveillance; (4) Intervention phase 2: introduced CRAB-positive patient cohorting, in addition to previous ongoing measures taken. CRAB was isolated from 204 patients aged 69.8y/o±15.86y, 59.8% male, 34.3% had CRAB-positive clinical samples. Mean hospital length-of-stay was 30.5days, with a 30-day postdischarge mortality rate of 55.9%. Mean CRAB clinical cases decreased from 0.89 in preintervention to 0.11 at the end of phase 2, with a change in slope and level after the intervention of P=.02 (CI: -0.204to -0.040) and P=.004 (CI: -0.013 to -0.003), respectively. This intervention, including enhanced environment cleaning, active surveillance, and patient cohorting, successfully reduced CRAB acquisition in IMWs and their HD non-ICUs.

Major risk factors and outcomes of the extensively drug-resistant Acinetobacter baumannii acquisition in a Moroccan surgical intensive care unit

Acinetobacter baumannii has emerged as an important nosocomial pathogen causing worldwide hospital outbreaks. The aim of this study was to determine the antibiotic resitance profile, the risk factors and outcomes related to the acquisition of extensively drug-resistant A. baumannii.

Acinetobacter baumannii Isolates from COVID-19 Patients in a Hospital Intensive Care Unit: Molecular Typing and Risk Factors.

Infections caused by Acinetobacter baumannii represent a major concern for intensive care unit (ICU) patients. However, the epidemiology of these infections among COVID-19 patients has not been fully explored. The aims of this study were (i) to characterize the clonal spread of A. baumannii among COVID-19 patients admitted to the ICU of the Umberto I hospital of Rome during the first year of the pandemic and (ii) to identify risk factors for its acquisition. Isolates were analysed by pulsed-field gel electrophoresis, and a multivariable regression model was constructed. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated. Overall, 193 patients were included, and 102 strains were analysed. All isolates had highly antibiotic-resistant profiles and derived from two genotypes. The cumulative incidence of A. baumannii acquisition (colonization or infection) was 36.8%. Patients with A. baumannii had higher mortality and length of stay. Multivariable analysis showed that previous carbapenem use was the only risk factor associated with A. baumannii acquisition (aOR: 4.15, 95% CI: 1.78–9.64). We documented substantial A. baumannii infections and colonization and high levels of clonal transmission. Given the limited treatment options, effective prevention and containment strategies to limit the spread of A. baumannii should be implemented.

Impact of an Infectious Disease Specialist on an Antimicrobial Stewardship Program at a Resource-Limited, Non-Academic Community Hospital in Korea.

Background: Implementing a successful antimicrobial stewardship program (ASP) is difficult for non-academic community (NAC) hospitals due to insufficient infrastructure. Aim: We evaluated the impact of an infectious disease specialist (IDS) on implementing an ASP in a resource-limited setting in Korea. Methods: A retrospective study was performed at a NAC hospital between June 2015 and August 2018. An IDS has led an ASP at the hospital since June 2017. We used an interrupted time series analysis to evaluate longitudinal effects of the IDS-led ASP on the amount of antibiotic use and incidence of multidrug-resistant organism (MDRO) acquisition. Findings: Total antibiotic use changed from 698.82 ± 74.41 to 602.09 ± 69.94 defined daily dose/1000 patient-days (PDs) after intervention. An immediate reduction in the use of carbapenems, glycopeptides, penicillins, and other antibiotics followed the IDS-led ASP. The 3rd/4th generation cephalosporins and carbapenems prescription rates decreased in slope after the intervention. Incidence of MDRO acquisition changed from 1.38, 0.78, and 0.21/1000 PDs to 1.06, 0.15, and 0.32/1000 PDs in methicillin-resistant Staphylococcus aureus, multidrug-resistant Acinetobacter baumannii, and multidrug-resistant Pseudomonas aeruginosa, respectively. The incidence of methicillin-resistant Staphylococcus aureus and multidrug-resistant Acinetobacter baumannii acquisition immediately decreased following intervention. Conclusion: An IDS can implement a successful ASP by reducing antibiotic consumption and MDRO acquisition at resource-limited NAC hospitals.

Multiple carbapenemase gene production by Acinetobacter baumannii isolates from burn patients in Iran

Objective: Acinetobacter baumannii is among the major Gram-negative nosocomial pathogens, and their antibiotic resistance has spread extensively; especially in burn settings. Methods: A total of 300 clinical isolates of A. baumannii were collected from burn patients hospitalized in burn settings. The isolates were examined for antimicrobial susceptibility testing by the disc diffusion method. The class D (bla(OXA-51)-like, bla(OXA-23)-like, bla(OXA-58)-like and bla(OXA-24)-like) and class B (encoded by bla(VIM) and bla(SIM)) carbapenemase genes were investigated by multiplex PCR. Results: A high level of carbapenem resistance was observed among isolates, but none of them were resistant to colistin. Among carbapenem-resistant A. baumannii, previous antibiotic consumption was significantly higher (significant risk factor for carbapenem-resistant A. baumannii acquisition) than other risk factors (P = 0.0123), whereas older age of patients was not significantly higher among other ranges in multivariate analysis by analysis of variance (ANOVA test). The bla(OXA-51-like) gene was the predominant gene, followed by bla(OXA-23-like), bla(OXA-24-like), bla(OXA-58-like), bla(SIM), bla(NDM) and bla(VIM) genes being 66, 35.33, 22, 14, 1.33, 1.33 and 13.33%, respectively. Furthermore, the co-existence of bla(OXA-51-like)/bla(OXA-23-like), bla(OXA-51-like)/bla(OXA-23-like)/bla(OXA-24-like) and bla(OXA-51-like)/bla(OXA-24-like) were 22.67, 12 and 11.33%, respectively. Conclusion: A high level of class D and class B carbapenemases among A. baumannii strains in the burn settings is a crisis in the eradication of infections caused by MDR, XDR and PDR strains. Therefore, the uncontrolled consumption of last-line antibiotics should be restricted and infection control strategies must be implemented accurately. Copyright (C) 2019 Wolters Kluwer Health, Inc. All rights reserved.

Acinetobacter Infections in Neonates

MDR-Gram-negative bacteria are a great concern in the neonatal population, with a worldwide rise in the reported incidence and with very limited therapeutic options. Acinetobacter baumannii is responsible for many infections in neonates and outbreaks in neonatal intensive care unit (NICU); also, outbreaks caused by other Acinetobacter species have been reported. The aim of this review is to document the epidemiology of Acinetobacter spp. infections in neonates and risk factors for acquisition of Acinetobacter spp. in the NICU using data from published studies. Acinetobacter spp. infections are increasing in neonates in NICU. Outbreak caused by multidrug resistant (MDR) or extensively drug resistant (XDR) A. baumannii but also outbreak caused by susceptible A. soli and A. septicus sp. nov., were reported in neonates. Acinetobacter spp. were responsible for bloodstream infections and respiratory tract infections in neonates. Risk factors for A. baumannii acquisition in neonates were low birthweight, length of NICU stay, umbilical catheterization, central-venous catheterization, assisted ventilation, and prior antibiotic use. This review highlights the importance of surveillance of risk factors for healthcare-associated infections in NICU to control MDR and XDR A. baumannii infections in neonates.

Acquisition and clearance of multidrug resistant Acinetobacter baumannii on healthy young adults concurrently burned in a dust explosion in Taiwan: the implication for antimicrobial stewardship

BackgroundInformation is limited about the effect of restricted carbapenem use on clearance of multi-drug resistant Acinetobacter baumannii (MDRAB). We sought to determine the time effect of antibiotic exposure on multi-drug resistant Acinetobacter baumannii (MDRAB) acquisition and clearance.MethodsWe conducted a retrospective observational study at the intensive care units of a tertiary medical center. Forty-two of a cohort of previously healthy young adults who were concurrently burned by a dust explosion was included. Cases consisted of those from whom MDRAB was isolated during hospitalization. Controls consisted of patients from whom MDRAB was not isolated in the same period. Use of antimicrobial agents was compared based on days of therapy per 1,000 patient-days (DOT/1,000PD). A 2-state Markov multi-state model was used to estimate the risk of acquisition and clearance of MDRAB.ResultsMDRAB was discovered in 9/42 (21.4%) individuals. The cases had significantly higher use of carbapenem (652 DOT/1,000PD vs. 385 DOT/1,000PD, P < 0.001) before MDRAB isolation. For the cases, clearance of MDRAB was associated with lower use of carbapenem (469 DOT/1,000PD vs. 708 DOT/1,000PD, P = 0.003) and higher use of non-carbapenem beta-lactam (612 DOT/1,000PD vs. 246 DOT/1,000PD, P <0.001). In multi-state model, each additional DOT of carbapenem increased the hazard of acquiring MDRAB (hazard ratio (HR), 1.08; 95% confidence interval (CI) 1.01–1.16) and each additional DOT of non-carbapenem beta-lactam increased the protection of clearing MDRAB (HR, 1.25; 95% CI 1.07–1.46).ConclusionsBoth acquisition and clearance of MDRAB were related to antibiotic exposure in a homogeneous population. Our findings suggest that early discontinuation of carbapenem could be an effective measure in antibiotic stewardship for the control of MDRAB spreading.

Incidence, risk factors, and outcome of multidrug-resistant Acinetobacter baumannii acquisition during an outbreak in a burns unit

Multidrug-resistant Acinetobacter baumannii (MR-AB) can cause outbreaks in a burns unit. To study the incidence, risk factors and outcome of MR-AB colonization during an outbreak. A prospective study was conducted from April to November 2014 in a burns unit in Paris. Weekly surveillance cultures of patients and their environment were performed. MR-AB acquisition, discharge, or death without MR-AB colonization were considered as competing events. To identify risk factors for colonization, baseline characteristics and time-dependent variables were investigated in univariate and multivariate analyses using Cox models. MR-AB strains were genotypically compared using multi-locus sequence typing. Eighty-six patients were admitted in the burns unit during the study period. Among 77 patients without MR-AB colonization at admission, 25 (32%) acquired MR-AB with a cumulative incidence of 30% at 28 days (95% CI: 20-40). Median time to MR-AB acquisition was 13 days (range: 5-34). In multivariate analysis, risk factors for MR-AB acquisition were ≥2 skin graft procedures performed [hazard ratio (HR): 2.97; 95% confidence interval (CI): 1.10-8.00; P= 0.032] and antibiotic therapy during hospitalization (HR: 4.42; 95% CI: 1.19-16.4; P= 0.026). A major sequence type of MR-AB (ST2) was found in 94% and 92% of patients and environmental strains, respectively, with all strains harbouring the blaOXA-23 gene. MR-AB colonization increased length of hospitalization (HR: 0.32; 95% CI: 0.17-0.58; P=0.0002) by a median of 12 days. A high incidence of MR-AB acquisition was seen during this outbreak with most strains from patients and their environment belonging to single sequence type. MR-AB colonization was associated with more skin graft procedures, antibiotic use, and prolonged hospitalization.

Risk Factors and Impact on Clinical Outcome of Multidrug-Resistant Acinetobacter Baumannii Acquisition in Cardiac Surgery Patients.

Acinetobacter baumannii recently has emerged as an important nosocomial pathogen. The aim of this study was to assess the impact on mortality of multidrug-resistant A. baumannii (MDR-AB) infection/colonization in patients undergoing cardiac surgery and to investigate microbiologic characteristics, epidemiologic spread of this pathogen, and the relative containment measures. Single-center, retrospective cohort study of prospectively collected data. Cardiac surgery tertiary-care center. Patients with positive MDR-AB cultures from September 1, 2009 to December 31, 2011. Bivariate and multivariate analyses were performed to individualize the risk factors for MDR-AB-infections in cardiac surgery patients. To evaluate the MDR-AB attributable mortality, a retrospective matched cohort study was performed. Incidence density ratio (IDR) was calculated to compare the MDR-AB infection/colonization before and after the introduction of preventive measures adopted following the first cases. MDR-AB acquisition occurred in 14 patients (0,6%) of 2385 patients. At the multivariate analyses, preoperative use of inotropic drugs (OR 18.2, 95% CI 4.6-71.9) and logistic EuroSCORE (OR 1.09, 95% CI 1.06-1.13) were found as independent risk factors. Patients with MDR-AB had 57% cumulative in-hospital mortality; no statistical differences in mortality were observed in the matched group. IDR revealed a significantly decreased incidence of infection/colonization (0.3 per 1,000 days of stay compared with 0.03/1,000 days of stay, p = 0.0001) after the containment measures became effective. Sicker patients are more susceptible to be infected by A. baumannii, but mortality is not significantly higher compared with other patients with similar characteristics. Adequate measures are fundamental to control the spread of the infection.

Acinetobacter baumannii infections in a South African paediatric intensive care unit.

To describe and compare characteristics and outcomes of patients colonized or infected with Acinetobacter baumannii (cases) to a control group. A retrospective case-controlled study of patients admitted to a South African paediatric intensive care unit (PICU) between January and December 2010. Acinetobacter baumannii was isolated in 194 patients. Mortality was similar between cases (9.3%) and controls (9.8%). Median duration of PICU stay and mechanical ventilation in cases vs. controls was 10 vs. 2 (p < 0.0001) and 9 vs. 1 days (p < 0.0001), respectively. Admission diagnosis of traumatic brain injury [adjusted odds ratio (OR): 5.6, 95% CI: 1.2-27.0; p = 0.03] and duration of mechanical ventilation (adjusted OR: 1.4, 95% CI: 1.3-1.5; p < 0.0001) were independently associated with A. baumannii aquisition. Acinetobacter baumannii acquisition was common and associated with increased morbidity, but not increased mortality.

Safety and clinical outcomes of carbapenem de-escalation as part of an antimicrobial stewardship programme in an ESBL-endemic setting.

To evaluate the safety and clinical outcomes of patients who received carbapenem de-escalation as guided by an antimicrobial stewardship programme (ASP) in a setting where ESBL-producing Enterobacteriaceae are endemic. Patients receiving meropenem or imipenem underwent a prospective ASP review for eligibility for de-escalation according to defined institutional guidelines. Patients in whom carbapenem was de-escalated or not de-escalated, representing the acceptance and rejection of the ASP recommendation, respectively, were compared. The primary outcome was the clinical success rate; secondary outcomes included the 30 day readmission and mortality rates, the duration of carbapenem therapy, the incidence of adverse drug reactions due to antimicrobials, the acquisition of carbapenem-resistant Gram-negative bacteria and the occurrence of Clostridium difficile-associated diarrhoea (CDAD). The de-escalation recommendations for 300 patients were evaluated; 204 (68.0%) were accepted. The patient demographics and disease severity were similar. The clinical success rates were similar [de-escalated versus not de-escalated, 183/204 (89.7%) versus 85/96 (88.5%), P=0.84], as was the survival at hospital discharge [173/204 (84.8%) versus 79/96 (82.3%), P=0.58]. In the de-escalated group, the duration of carbapenem therapy was shorter (6 versus 8 days, P<0.001), the rate of adverse drug reactions was lower [11/204 (5.4%) versus 12/96 (12.5%), P=0.037], there was less diarrhoea [9/204 (4.4%) versus 12/96 (12.5%), P=0.015], there was a lower incidence of carbapenem-resistant Acinetobacter baumannii acquisition [4/204 (2.0%) versus 7/96 (7.3%), P=0.042] and there was a lower incidence of CDAD [2/204 (1.0%) versus 4/96 (4.2%), P=0.081]. This study suggests that the ASP-guided de-escalation of carbapenems led to comparable clinical success, fewer adverse effects and a lower incidence of the development of resistance. This approach is safe and practicable, and should be a key component of an ASP.

Effect of a ventilator-focused intervention on the rate of Acinetobacter baumannii infection among ventilated patients

Acinetobacter baumannii is a leading cause of ventilator-associated pneumonia, often as a result of ventilator equipment contamination. Evidence-based guidance on optimal care of ventilator equipment to prevent infection is lacking. Here, we report on a significant and persistent reduction in A baumannii infection rates achieved by introducing a strict policy on ventilator care. We implemented an institution-wide ventilator care policy that included routine exchange of breathing circuits and external bacterial filters (every 7-14 days) and replacement followed by routine sterilization of internal bacterial filters (every 4-8 weeks). We analyzed sputum cultures and patient outcomes among ventilated patients before and after the intervention. Between January 2012 and March 2013, 321 patients ventilated for more than 3 days comprised the study cohort. Health care-associated A baumannii acquisition was significantly reduced during the postintervention period (33% vs 16%; odds ratio, 0.39; 95% confidence interval, 0.23-0.67; P = .0008). Additionally, the median time to A baumannii acquisition was significantly longer postintervention (59 vs 21 days; P < .0001). A baumannii ventilator-associated pneumonia risk was also reduced postintervention (odds ratio, 0.39; P = .005). Implementing a stricter standard of ventilator care than that currently defined in published guidelines can significantly decrease health care-associated A baumannii acquisition and related adverse outcomes among ventilated patients.

The importance of colonization pressure in multiresistant Acinetobacter baumannii acquisition in a Greek intensive care unit.

IntroductionWe investigated the role of colonization pressure on multiresistant Acinetobacter baumannii acquisition and defined patient-related predictors for carriage at admission and acquisition during hospitalization in intensive care unit (ICU) patients.MethodsThis was a 12-month, prospective, cohort study of all patients admitted to a single ICU of a tertiary hospital. Screening samples were collected at ICU admission to identify imported carriers, and weekly during hospitalization to identify acquisition. Colonization pressure (carriers' patient-days × 100/all patients' patient-days) and the absolute number of carriers were calculated weekly, and the statistical correlation between these parameters and acquisition was explored. Multivariable analysis was performed to identify predictors for A. baumannii carriage at admission and acquisition during hospitalization. A. baumannii isolates were genotyped by repetitive-extragenic-palindromic polymerase chain reaction (PCR; rep-PCR).ResultsAt ICU admission, 284 patients were screened for carriage. A. baumannii was imported in 16 patients (5.6%), and acquisition occurred in 32 patients (15.7%). Acquisition was significantly correlated to weekly colonization pressure (correlation coefficient, 0.379; P = 0.004) and to the number of carriers per week (correlation coefficient, 0.499; P <0.001). More than one carrier per week significantly increased acquisition risk (two to three carriers, odds ratio (OR), 12.66; P = 0.028; more than four carriers, OR, 25.33; P = 0.004). Predictors of carriage at admission were infection at admission (OR, 11.03; confidence interval (CI), 3.56 to 34.18; P < 0.01) and hospitalization days before ICU (OR, 1.09; CI, 1.01 to 1.16; P = 0.02). Predictors of acquisition were a medical reason for ICU admission (OR, 5.11; CI, 1.31 to 19.93; P = 0.02), duration of antibiotic administration in the unit (OR, 1.24; CI, 1.12 to 1.38; P < 0.001), and duration of mechanical ventilation (OR, 1.08; CI, 1.04 to 1.13; P = 0.001). All strains were multiresistant. Rep-PCR analysis showed one dominant cluster.ConclusionsAcquisition of multiresistant A. baumannii in ICU patients is strongly correlated to colonization pressure. High levels of colonization pressure and more than two carriers per week independently increase acquisition risk. Patient-related factors, such as infection at admission and long hospitalization before the ICU, can identify imported A. baumannii carriers. Medical patients with extended administration of antibiotics and long duration of mechanical ventilation in the ICU were the most vulnerable to acquisition.

Comparison of Risk Factors for Recovery of Acinetobacter baumannii during Outbreaks at Two Kentucky Hospitals, 2006

Acinetobacter baumannii (A. baumannii) is a well-described cause of nosocomial outbreaks and can be highly resistant to antimicrobials. We investigated A. baumannii outbreaks at two Kentucky hospitals to find risk factors for Acinetobacter acquisition in hospitalized patients. We performed case-control studies at both hospitals. We defined a case as a clinical culture growing A. baumannii from a patient from August 1 to October 31, 2006 (Hospital A), or April 1 to October 31, 2006 (Hospital B). Twenty-nine cases were identified at Hospital A and 72 cases were identified at Hospital B. The median case patient age was 42 years in Hospital A and 46 years in Hospital B. The majority of positive cultures were from sputum (Hospital A, 51.7%; Hospital B, 62.5%). The majority of case patients had multidrug-resistant A. baumannii (Hospital A, 75.9%; Hospital B, 70.8%). Using logistic regression, controlling for age and admitting location, mechanical ventilation (Hospital A odds ratio [OR] = 21.6; 95% confidence interval [CI] 3.5, 265.9; Hospital B OR = 4.5, 95% CI 1.9, 11.1) was associated with A. baumannii recovery. Presence of a nonsurgical wound (OR = 6.6, 95% CI 1.2, 50.8) was associated with recovery of A. baumannii at Hospital A. We identified similar patient characteristics and risk factors for A. baumannii acquisition at both hospitals. Our findings necessitate the importance of review of infection control procedures related to respiratory therapy and wound care.

Impact of multi-drug-resistant Acinetobacter baumannii on clinical outcomes

We conducted a retrospective matched cohort study to examine the impact of isolation of multi-drug-resistant (MDR) Acinetobacter baumannii on patient outcomes. Cases from whom MDR A. baumannii was isolated in a clinical culture (n = 118) were compared with controls from whom MDR A. baumannii was not isolated (n = 118). Cases and controls were matched according to ward, calendar month of hospitalization, and duration of hospitalization before culture. The following outcomes were compared in multivariable analysis: in-hospital mortality, length of stay, need for mechanical ventilation, and functional status at discharge. MDR A. baumannii was determined to be a pathogen in 72% of cases. In 36% of cases, the patient died, versus 21% of controls (odds ratio [OR] 2.21, 95% confidence interval [CI] 1.17-4.16, P = 0.014). Median length of stay for surviving cases was 17 days, versus 11 for surviving controls (multiplicative effect 1.55, 95% CI 0.99-2.44, P = 0.057). Fifty-two percent of cases required mechanical ventilation, versus 25% of controls (OR 3.72, 95% CI 1.91-7.25, P<0.001); 60% of surviving cases were discharged with reduced functional status, versus 38% of controls (OR 4.4, 95% CI 1.66-11.61, P = 0.003). In multivariable analysis, clinical isolation of MDR A. baumannii remained a significant predictor of mortality (OR 6.23, 95% CI 1.31-29.5, P = 0.021), need for mechanical ventilation (OR 7.34, 95% CI 2.24-24.0, P<0.001), and reduced functional status on discharge (OR 7.93, 95% CI 1.1-56.85, P = 0.039). Thus, MDR A. baumannii acquisition is associated with severe adverse outcomes, including increased mortality, need for mechanical ventilation, and reduced functional status.

Attributable mortality of Acinetobacter baumannii infections in critically ill patients: a systematic review of matched cohort and case-control studies

IntroductionThere has been a continuing controversy about whether infection with Acinetobacter baumannii increases morbidity and mortality independently of the effect of other confounding factors.MethodsWe performed a systematic review of matched case-control and cohort studies examining the mortality attributable to infection with or acquisition of A. baumannii (infection or colonization). We included in our review studies that compared mortality and/or morbidity of patients with acquisition of or infection with A. baumannii (cases) with the outcomes of matched patients without A. baumannii isolation from clinical specimens (controls). The relevant studies were identified from searches of the PubMed and the Cochrane Library databases. Two independent reviewers performed the literature search, study selection, and data extraction from nine identified relevant studies.ResultsThe attributable mortalities, in the hospital and in the intensive care unit, of patients with A. baumannii infection in six matched case-control studies included in our review ranged from 7.8% to 23% and from 10% to 43%, respectively. In addition, a statistically significantly higher mortality was reported for patients with A. baumannii acquisition; that is, colonization or infection (cases) compared with controls without such an acquisition in all four reviewed studies that reported data on this comparison.ConclusionAlthough definitive statements about the mortality attributable to the acquisition of A. baumannii cannot be made from the available studies because of their methodological heterogeneity, the reviewed data suggest that infection with or acquisition of A. baumannii seems to be associated with increased mortality.

Investigation of a nosocomial outbreak of extended-spectrum β-lactamase VEB-1-producing isolates of Acinetobacter baumannii in a hospital setting

A nosocomial outbreak of epidemiologically related VEB-1 extended-spectrum beta-lactamase-producing isolates of Acinetobacter baumannii occurred in 33 patients in an intensive care unit. A case-control study identified previous treatment with third-generation cephalosporins as the only risk factor for A. baumannii acquisition. Rationale for antibiotic use should be strengthened.

Nosocomial multi-drug resistant Acinetobacter baumannii bloodstream infection: risk factors and outcome with ampicillin-sulbactam treatment

The emergence of multidrug-resistant (MDR) Acinetobacter baumannii poses a therapeutic problem. The aim of this study was to assess the risk factors for nosocomial MDR- A. baumannii bloodstream infection (BSI) and the efficacy of ampicillin-sulbactam (A/S) in its treatment. Of 94 nosocomial A. baumannii BSI during the year 2000, 54% involved MDR strains, 81% of which were genetically related. Various risk factors for MDR- A. baumannii were found, of which intensive-care unit admission and prior aminoglycoside therapy were independently associated with MDR- A. baumannii acquisition on multivariate analysis. Of MDR- A. baumannii BSI cases, 65% received A/S and 35% inadequate antibiotic therapy, whereas of 43 non-MDR cases, 86% were treated according to susceptibility and 14% inappropriately with antibiotics to which these organisms were resistant. Crude mortality was comparable in the adequately treated groups. Respective mortalities among patients treated adequately and inadequately were 41.4 and 91.7% ( p<0.001). Among severely ill patients, A/S therapy significantly decreased the risk of death ( P=0.02 OR=7.64). MDR- A. baumannii has become highly endemic in our institution. A/S appears to be one of the last effective and safe empirical resorts for treatment of MDR A. baumannii BSI.

Mortality and the increase in length of stay attributable to the acquisition of Acinetobacter in critically ill patients.

To determine the impact of Acinetobacter baumannii (AB) acquisition in intensive care unit (ICU) patients on mortality and length of stay (LOS). Pairwise matched 1:1 case-control study. Medical-surgical ICU in a tertiary health care institution. During 16 months, all patients admitted to the ICU were eligible. Case patients were defined as every patient with an AB isolation 48 hrs after ICU admission. Control patients were retrospectively selected from ICU patients without any AB isolation, according to seven matching variables. Attributable mortality and excess LOS in the ICU were measured. Eighty-seven patients were included, with 75 pairs successfully matched. Infection was defined in 48 patients (23 respiratory). The attributable mortality rate for AB acquisition was 30% (49% vs.19%) (95% confidence interval [CI] = 23%, 37%): 43% (CI = 34%, 52%) in patients with infection (58% vs.15%) and 53% (CI = 41%, 65%) in patients with respiratory infections (70% vs.17%). The estimated risk rates for death were 2.6 (CI = 1.6, 4.5; p < .001), 4.0 (CI = 1.9, 8.3; p < .001), and 4.0 (CI = 1.6, 10.2; p < .01), respectively. The attributable excess LOS was 13 days for both AB acquisition and infection (23 vs. 10 days; p < .001) and respiratory infections (23 vs. 10 days; p < .01). In noninfected patients, no significant excess of mortality was found (33% vs. 26%), but LOS increased in 15 days. AB acquisition involved an excess LOS in ICU patients and increased risk of death, but the latter could be found only in patients with proven infection.

Unusual genetic heterogeneity of Acinetobacter baumannii isolates in a university hospital in Italy

Background:Acinetobacter baumannii has become an increasingly important nosocomial pathogen, particularly in intensive care units (ICUs). The aim of this investigation was to study the molecular epidemiology of A baumanii in a university hospital in Italy. Methods: All A baumanii isolates were collected and typed with phenotypic and genotypic methods during a 7-month period. A 1-year prospective surveillance of ICU-acquired infections was performed by using the National Nosocomial Infections Surveillance methodology. Results:A baumanni accounted for 28.4% of all infections and 46.7% of all pneumonia acquired in the ICU, with a nosocomial infection rate of 12.4% or 8 infections per 1000 patient-days. Risk factors for A baumannii acquisition in the ICU were mechanical ventilation and previous use of broad-spectrum antibiotics, whereas administration of carbapenems showed a significant protective effect. Pulsed-field gel electrophoresis of genomic Apa I digests identified at least 5 outbreaks in the ICU caused by 5 different clones, one replacing the other in a well-defined temporal order. Conclusions: Whereas the sequential temporal cluster of epidemic clones in the ICU is intriguing and requires further research, the clear evidence of cross-contamination of A baumannii isolates involved with infections in the ICU demands extensive preventive efforts. (AJIC Am J Infect Control 1999;27:247-53)