Acinetobacter Baumannii Bloodstream Infections Research Articles

Analysis of risk factors on prognosis of Acinetobacter baumannii bloodstream infection

To explore the risk factors on prognosis of Acinetobacter baumannii bloodstream infection. Clinical data from 78 patients with Acinetobacter baumannii bloodstream infection hospitalized in First Affiliated Hospital of Nanjing Medical University from January 2010 to November 2012 were analyzed retrospectively. According to the 28-day prognosis after admission, the patients were divided into non-survivors (n=40) and survivors (n=38). Data on demographic and clinical characteristics, wards, underlying diseases, treatments, invasive medical procedures, bacterial resistance to antibiotics, and acute physiology and chronic health evaluation II (APACHEII) score in the beginning were collected. The index as an independent risk factor of mortality was demonstrated by multivariate logistic regression analysis. The predictor value was concluded by comparing area under the receiver operating characteristic curve (ROC curve) of each index. Risk factors of mortality of Acinetobacter baumannii bloodstream infection goes as following, including intensive care unit admission[ICU, odds ratio (OR)=12.9,95% confidence interval (95%CI) 2.4-63.5, P=0.001], trachea intubation or tracheostomy (OR=6.2, 95%CI 1.5-30.4, P=0.023), invasive mechanical ventilation (OR=5.1, 95%CI 1.4-22.6, P=0.042), invasive medical procedure besides central venous catheter (including thoracentesis, bone marrow puncture, lumbar puncture, catheterization, bronchoalveolar lavage with bronchofibroscope, arteriovenous fistula plastic operation, OR=8.4, 95%CI 1.7-37.8, P=0.011), APACHEII score ≥19 in the beginning (OR=35.4, 95%CI 3.8-318.6, P=0.001). With respect to APACHE II score≥ 19 as mortality cut-off point, an area under the receiver operating curve of 0.938 was statistically significant (P<0.05), with sensitivity 76.2% and specificity 94.1%. The relationship between prognosis and antibiotic resistance did not have statistically significance. Invasive medical procedures and treatments were associated with increased mortality of patients with Acinetobacter baumannii bloodstream infection. A strong predictor of adverse outcome in such conditions was APACHEII score ≥19.

Control of an Acientobacter baumannii outbreak in a neonatal ICU without suspension of service: a devastating outbreak in Diyarbakir, Turkey

A nosocomial outbreak of Acinetobacter baumannii bloodstream infections (Ab-BSI) was identified in Diyarbakir Children's Hospital's (Diyarbakir, Turkey) 60-bed Neonatal Intensive Care Unit (NICU) in 2006 and 2007. The investigation and control of the outbreak were based on case-control and epidemiological studies as well as multifaceted interventions. Sixty-four neonates (case patients) with Ab-BSI and 128 neonates (control patients) free of Ab-BSI, who had been hospitalized at the unit during the outbreak period, were included in the study. Case and control patients were compared for possible predisposing factors (e.g., gender, length of NICU stay, antibiotic use, intubation, etc.). An intervention program (cohorting, education, reinforcing hand hygiene, antibiotic restriction, improving processes of patient care, environmental cleaning, and barrier isolation) was implemented to control the outbreak. Surveillance cultures were collected from all possible sources, and the epidemiological investigation was supplemented by a pulsed field gel electrophoresis (PFGE) study. Fifty-three neonates (82.8%) died in the case group and 51 (39.8%) in the control group (P < 0.001). The duration of stay at the NICU [odds ratio (OR) 1.15; 95% confidence interval (CI) 1.07-1.23; P < 0.001] and re-intubation (OR 38.62; CI 12.66-117.87; P < 0.001) were found to be significant risk factors for Ab-BSI. Surveillance cultures showed a heavy contamination in the NICU, and the outbreak ended after a series multifaceted interventions. All A. baumannii isolates, both from the cases and environmental samples, had an identical PFGE fingerprint pattern. The control of Ab-BSI requires a multifaceted intervention program and complex efforts and implementations, especially if the ICU does not implement any suspension of care provision.

Impact of Carbapenem Resistance and Receipt of Active Antimicrobial Therapy on Clinical Outcomes of Acinetobacter baumannii Bloodstream Infections

Nosocomial Acinetobacter baumannii bloodstream infections occur with significant prevalence and mortality. The relationship between carbapenem resistance in A. baumannii and patient outcomes remains unclear. A retrospective cohort study was conducted on patients with A. baumannii bacteremia. Outcomes, controlling for confounders, were compared for carbapenem-nonresistant A. baumannii (CNRAB) and carbapenem-resistant A. baumannii (CRAB). The primary outcome studied was all-cause hospital mortality, and the secondary endpoints evaluated were time to mortality, time to negative cultures, and length of stay postinfection for survivors. A total of 79 patients, 37 infected with CRAB and 42 with CNRAB, were studied. Hospital mortality was greater in the CRAB group as determined based on bivariate analysis (P < 0.01); however, this effect was nullified when controlling for relevant confounders with logistic regression and a Cox proportional-hazards model (P = 0.71 and 0.75, respectively). Values for time to mortality and time to negative cultures did not differ between the groups. The median number of days of stay postinfection for survivors was greater for the CRAB group than the CNRAB group (14 versus 6.5; P < 0.01). Patients who received active antimicrobial therapy were less likely to die (93.5% versus 74.2%; P = 0.02), regardless of carbapenem susceptibility classifications, and this result was robust in the multivariate model (P = 0.02). Trends existed for improved outcomes in patients receiving an active beta-lactam, and patients fared worse if they had received a polymyxin as an active agent. Patients with CRAB bloodstream infections were more chronically ill and had more comorbidities. Inactive therapy was more important than carbapenem susceptibility with respect to outcomes, was a strong predictor of death, and is potentially modifiable.

Risk factors and outcomes of imipenem–resistant Acinetobacter bloodstream infection in North–eastern Malaysia

Objective To determine the risk factors and outcomes of imipenem–resistant Acinetobacter baumannii (IRAB) bloodstream infection (BSI) cases, since there is very little publication on Acinetobacter baumannii infections from Malaysia. Methods A cross sectional study of 41 cases (73.2%) of imipenem–sensitive Acinetobacter baumanii (ISAB) and 15 cases (26.8%) of IRAB was conducted in a teaching hospital which was located at North–Eastern state of Malaysia. Results There was no independent risk factor for IRAB BSI identified but IRAB BSI was significantly associated with longer bacteraemic days [ OR 1.23 (95% CI 1.01, 1.50)]. Although prior use of carbepenems and cephalosporin were higher among IRAB than ISAB group, statistically they were not significant. There was no significant difference in term of outcomes between the two groups. Conclusions Although statistically not significant, this analysis compliments previous publication highlighting the importance of appropriate empiric antibiotic usage in hospital especially carbepenems and need further evaluation with bigger subjects.

Patients with Acinetobacter baumannii bloodstream infections are colonized in the gastrointestinal tract with identical strains

In this study, we identified critically ill patients with Acinetobacter baumannii bacteremia and examined perirectal surveillance cultures for the presence of genetically related A baumannii strains using pulsed-field gel electrophoresis to determine whether gut colonization preceded clinical infection. Seven patients with imipenem-resistant A baumannii bacteremia were identified from January to June of 2008. Six of 7 (86%) patients were colonized in the gastrointestinal tract with genetically similar strains preceding their bacteremia.

Impact of early appropriate antimicrobial therapy on survival in Acinetobacter baumannii bloodstream infections

The impact of appropriate empirical antimicrobial therapy for Acinetobacter baumannii bacteraemia on patient outcomes has not been clearly established. We assessed predictors of 30-day mortality and the effect of inappropriate empirical antimicrobial treatment on mortality among patients with A. baumannii bacteraemia between July 2005 and June 2008. Initial empirical antimicrobial therapy was considered to be appropriate if the initial antibiotics that were administered within 48 h after the acquisition of a blood culture sample included at least one antibiotic that was active in vitro and when the dosage and route of administration were in accordance with current medical standards. Overall, 103 patients with nosocomial A. baumannii bacteraemia were included in the study. Appropriate empirical therapy was administered to 41.7% of patients within 48 h. The overall mortality rate was 54.4%, with rates of 39.5% and 65% for patients who received appropriate and inappropriate antimicrobial therapy within 48 h, respectively. Thus, a 25.5% reduction in the overall crude mortality rate was associated with adequate early empirical antimicrobial therapy. Multivariate analysis using a Cox regression model showed that significant independent risk factors for mortality were delayed appropriate treatment [hazard ratio (HR) = 2.4, 95% confidence interval (CI) 1.3–4.2; P = 0.004], development of septic shock (HR = 2.6, 95% CI 1.4–4.8; P = 0.004), age > 65 years (HR = 2.1, 95% CI 1.2–3.7; P = 0.007) and mechanical ventilation (HR = 3.3, 95% CI 1.5–7.4; P = 0.003). It is concluded that a delay in receiving appropriate antimicrobial therapy had an adverse influence on clinical outcome in patients with A. baumannii bacteraemia.

Risk factors and impact of nosocomial Acinetobacter baumannii bloodstream infections in the adult intensive care unit: a case–control study

During a nine-year study period, 96 episodes of nosocomial bloodstream infection (BSI) due to Acinetobacter baumannii were identified in the adult intensive care units (ICUs) of Shin Kong Wu Ho-Su Memorial Hospital. Seventy-seven (80.2%) of these were available for matching in terms of age, sex, primary diagnosis of ICU admission, ICU ward, and disease severity. Univariate analysis showed that central venous catheter use, ventilator use, prior A. baumannii colonisation, and respiratory and cardiovascular organ failure were significantly associated with acquiring A. baumannii BSI in the ICU. By multivariate analysis, only prior A. baumannii colonisation [odds ratio (OR): 3.81; P<0.001] and cardiovascular failure (OR: 2.24; P=0.04) were identified as independent risk factors. The lower respiratory tract (32/77; 41.6%) was the most frequent source of infection, followed by intravascular catheters (13/77; 16.9%). Cumulative survival curves for patients with A. baumannii BSI and control patients showed no significant difference (30 day crude mortality: 29.9% and 27.3%, respectively; P=0.916). However, the mean length of ICU and hospital stay and mean hospital cost of patients with A. baumannii BSI significantly increased, with an estimated 8.7 days excess length of ICU stay, 19.1 days excess hospital stay, and US $8480 extra hospital costs. Imipenem and meropenem remained the most active antimicrobial agents, both with 95.5% susceptibility (MIC50=0.25 and 0.5, respectively). Improving hand hygiene of healthcare workers and aseptic care of vascular catheters and endotracheal tubes are important measures to prevent A. baumannii colonisation and decrease the incidence of BSI.

Acinetobacter baumannii bloodstream infection while receiving tigecycline: a cautionary report

Tigecycline has shown in vitro activity against Acinetobacter baumannii. Yet, published clinical experience with tigecycline use outside clinical trials is lacking. We describe, for the first time, bloodstream infection caused by tigecycline-non-susceptible A. baumannii occurring in patients receiving tigecycline for other indications. The possible mechanisms of resistance and pharmacokinetic limitations of the drug are addressed. The clinical records of involved patients were systematically reviewed. Tigecycline susceptibility testing was initially performed using the Etest method and confirmed by agar dilution. Involved isolates underwent PFGE and exposure to phenyl-arginine-beta-naphthylamide (PAbetaN), an efflux pump inhibitor. Two patients developed A. baumannii bloodstream infection while receiving tigecycline. Tigecycline was administered for other indications for 9 and 16 days, respectively, before the onset of A. baumannii infection. Patient 1 died of overwhelming A. baumannii infection and Patient 2 recovered after a change in antibiotic therapy. The MICs of tigecycline were 4 and 16 mg/L, respectively. Both isolates had a multidrug-resistant phenotype and were genotypically unrelated. After exposure to PAbetaN, the MICs reduced to 1 and 4 mg/L, respectively. To our knowledge, this is the first clinical description of bloodstream infection caused by tigecycline-non-susceptible A. baumannii. Such resistance appears to be at least partly attributable to an efflux pump mechanism. Given the reported low serum tigecycline levels, we urge caution when using this drug for treatment of A. baumannii bloodstream infection.

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.

Acinetobacter baumannii bloodstream infection: clinical features and antimicrobial susceptibilities of isolates.

The number of nosocomial infections caused by Acinetobacter baumannii has increased in recent years. The purposes of this study are to discover the risk factors of transmission to prevent the nosocomial infection of A. baumannii. We retrospectively studied 36 patients with A. baumannii bacteremia at China Medical College Hospital from January 1996 to December 1997. There were 23 males and 13 females. All bacteremia were acquired nosocomially. Malignancy (n = 8) and intracranial hemorrhage (n = 6) were the most common underlying diseases. Only one patient on arterial line disclosed intraarterial catheter-related A. baumannii bacteremia and 3 patients had evidence of A. baumannii pneumonia. Twenty-one patients (58%) had central venous catheters in place at the onset of bacteremia, but none was proven to be catheter-related infection. There were 32 patients (89%) with unknown portal of entry. Multivariate logistic regression analysis revealed that potential risk factors related to A. baumannii bacteremia were prior antimicrobial therapy (P < 0.05). The most common clinical features of A. baumannii bacteremia were, in descending order, fever, leukocytosis, thrombocytopenia and hypotension. Eleven patients (30.6%) died directly from A. baumannii bacteremia. All isolates were resistant to ampicillin, cephalothin, cefonicid and moxalactam. The most alarming evidence was that 19% of isolates showed resistance to imipenem. Our findings emphasized that A. baumannii bacteremia had the following characteristics: usually acquired nosocomially, unknown portal of entry, and high multiresistance, especially the increasing resistance rate to imipenem. Imipenem must be reserved as a last-line agent to treat A. baumannii infections, so we want to suggest that the treatment of choice for A. baumannii is gentamicin, amikacin or ceftazidime.

Risk factors for nosocomial bloodstream infections due to Acinetobacter baumannii: a case-control study of adult burn patients.

Risk factors for Acinetobacter baumannii bloodstream infection (BSI) were studied in patients with severe thermal injury in a burn intensive care unit where A. baumannii was endemic. Of 367 patients hospitalized for severe thermal injury during the study period, 29 patients with nosocomial A. baumannii BSI were identified (attack rate, 7.9%). Cases were compared with 58 matched controls without A. baumannii BSI. The overall mortality rate was 31% among cases and 14% among controls; only two deaths (7%) were considered directly related to A. baumannii BSI. Molecular typing of A. baumannii blood isolates by means of randomly amplified polymorphic DNA analysis and pulsed-field gel electrophoresis revealed the presence of three different strain types. Multivariate analysis showed that female gender (P = .027), total body surface area burn of > 50% (P = .016), prior nosocomial colonization with A. baumannii at a distant site (P = .0002), and use of hydrotherapy (P = .037) were independently associated with the acquisition of A. baumannii BSI in burn patients. These data underscore the need for effective infection control measures for this emerging nosocomial problem.