Carbapenem Breakpoints for Acinetobacter baumannii Group: Supporting Clinical Outcome Data from Patients with Bacteremia.

The carbapenem breakpoints set by different organizations for Acinetobacter are discordant, but supporting clinical data are lacking. This study aimed to provide the first clinical outcome data to support the carbapenem breakpoints for Acinetobacter baumannii (Ab) group in patients with bacteremia. This study included 117 adults who received carbapenems for treatment of Ab group bacteremia in Taipei Veterans General Hospital over an 8-year period. We analyzed 30-day mortality rates among patient groups acquiring isolates with different carbapenem minimal inhibitory concentrations (MICs). The carbapenem MIC breakpoint derived from classification and regression tree (CART) analysis to delineate the risk of 30-day mortality was between MICs of ≤ 4 mg/L and ≥ 8 mg/L. Mortality rate was higher in patients acquiring isolates with carbapenem MIC ≥ 8 mg/L than ≤ 4 mg/L, by bivariate (54.9% [28/51] vs 25.8% [17/66]; P = 0.003) and survival analysis (P = 0.001 by log-rank test). Multivariate analysis using logistic regression and Cox regression models including severity of illness indices demonstrated that treating patients with Ab group bacteremia caused by isolates with a carbapenem MIC ≥ 8 mg/L with carbapenem was an independent predictor of 30-day mortality (odds ratio, 5.125; 95% confidence interval [CI], 1.946-13.498; P = 0.001, and hazard ratio, 2.630; 95% CI, 1.431-4.834; P = 0.002, respectively). The clinical outcome data confirmed that isolates with MIC ≤ 4 mg/L were susceptible to carbapenem, and those with MIC ≥ 8 mg/L were resistant in patients with Ab group bacteremia.

Comparison between patients under hemodialysis with community-onset bacteremia caused by community-associated and healthcare-associated methicillin-resistant Staphylococcus aureus strains.

BACKGROUND/PURPOSE(S): Patients receiving hemodialysis infected with methicillin-resistant Staphylococcus aureus (MRSA) have been considered to have healthcare-associated (HA) infections, but strains with community-associated (CA) characteristics have also been identified in this population. The authors compared infections of the two strains among patients with end-stage renal disease. METHODS: From January 2004 to December 2008 the authors analyzed the demographic and microbiologic data of 57 patients with community-onset (defined as a positive culture obtained ≤ 48 hours after admission) MRSA bacteremia and end-stage renal disease at a 2900-bed tertiary medical center. MRSA isolate with staphylococcal cassette chromosome mec (SCCmec) type II/III was classified as HA strains, and SCCmec type IV/V as CA strains. RESULTS: Forty-seven patients (82%) had HA-MRSA strains and 10 patients (18%) had CA-MRSA strains. The major clones of HA-MRSA were sequence type (ST) 5 with SCCmec type II and staphylococcal protein A (spa) t002 as well as ST239 carrying SCCmec type III and spa t037. The CA-MRSA strains were predominantly ST59, more susceptible to non-ß-lactam antimicrobial agents, and had a higher percentage of carrying the Panton-Valentine leukocidin gene in comparision with the HA-MRSA strains. Patients infected with HA-MRSA isolates had a higher overall mortality (57.4%, p = 0.012). In multivariate analysis, male patients were more likely to be infected with HA-MRSA isolates than CA-MRSA strains (p = 0.037), and a history of receiving urinary catheterization within 1 year prior to bacteremia onset (p = 0.047) is an independent risk factor to acquiring HA-MRSA strains. CONCLUSION: Patients undergoing dialysis and infected with HA-MRSA strains had higher mortality rates and were more commonly associated with urinary catheterization within 1 year before bacteremia.

Evaluation of the effect of appropriate antimicrobial therapy on mortality associated with Acinetobacter nosocomialis bacteraemia.

Appropriate antimicrobial therapy is effective for severe infections caused by Acinetobacter baumannii, but efficacy for other Acinetobacter species remains to be established. The current study was designed to determine whether appropriate antimicrobial therapy reduces the mortality of patients with Acinetobacter nosocomialis bacteraemia. A 9-year retrospective study of 266 patients with monomicrobial A. nosocomialis bacteraemia was conducted at a large teaching hospital in Taiwan. Multivariable analysis was performed to evaluate the impact on 14-day mortality according to clinical characteristics, severity of disease and use of appropriate antimicrobial therapy. The influence of APACHE II score on the impact of appropriate antimicrobial therapy was analysed by including an interaction term. The overall 14-day mortality was 9.4%. Multivariable analysis revealed that APACHE II score was the only factor significantly associated with mortality (odds ratio, 1.18; 95% confidence interval, 1.11-1.25; p <0.001). Appropriate antimicrobial therapy was not associated with reduced mortality regardless of disease severity. In the subgroup analyses in patients with different clinical conditions, APACHE II score was consistently an independent factor for 14-day mortality, and appropriate antimicrobial therapy did not affect the mortality in any group. In conclusion, severity of disease, based on the APACHE II score, was the independent risk factor for 14-day mortality for patients with monomicrobial A. nosocomialis bacteraemia, even in different clinical conditions. In contrast, appropriate antimicrobial therapy did not reduce the 14-day mortality. The result highlighted a different effect of appropriate antimicrobial therapy on infections caused by two phenotypically undifferentiated Acinetobacter.

Risk factors and clinical outcomes of patients with carbapenem-resistant Acinetobacter baumannii bacteremia.

BACKGROUND: It is still controversial whether carbapenem-resistant Acinetobacter baumannii (CRAB) is an independent risk factor for mortality. This study aimed to determine the risk factors and outcomes of patients with CRAB bacteremia, compared to those with carbapenem-susceptible A. baumannii (CSAB) bacteremia. METHODS: This retrospective cohort study was conducted in Taipei Veterans General Hospital, Taiwan. Patients with bacteremia due to A. baumannii during June 2002 and December 2007 were included. RESULTS: A total of 62 patients with CRAB and 164 with CSAB bacteremia were included. Among these patients, the independent risk factors for acquiring CRAB bacteremia were hematological malignancy [odds ratio (OR): 4.04; 95% confidence interval (CI): 1.29-12.70; p = 0.017], previous use of cefepime (OR: 2.60; 95% CI 1.11-6.08; p = 0.028) and use of total parenteral nutrition (OR: 3.06; 95% CI 1.12-8.39; p = 0.029). The patients with CRAB bacteremia had higher mortality rate than those with CSAB bacteremia. However, multivariate analysis showed that among patients with A. baumannii bacteremia, acquisition of CRAB by itself was not an independent risk factor for 14-day mortality. Instead, the independent factors predicting14-day mortality were Acute Physiology and Chronic Health Evaluation (APACHE) score > 20 (OR: 6.33; 95% CI: 2.32-17.26; p < 0.001), shock (OR: 2.68; 95% CI: 1.11-6.23; p = 0.025) and inappropriate antimicrobial therapy (OR: 2.14; 95% CI: 1.01-4.53; p = 0.046). CONCLUSION: Risk factors for CRAB bacteremia were hematological malignancies, previous use of cefepime and use of total parenteral nutrition. Acquisition of CRAB itself is not a poor prognostic factor for the patients with A. baumannii bacteremia.

Clinical characteristics of Acinetobacter baumannii complex bacteremia in patients receiving total parenteral nutrition.

BACKGROUND: Acinetobacter baumannii complex (Abc) comprises at least three phenotypically undifferentiated species, including A baumannii, Acinetobacter genomic species 3 (AGS 3) and Acinetobacter genomic species 13TU (AGS 13TU). Abc bacteremia had rarely been described in patients receiving total parenteral nutrition (TPN). In this study, we aimed to determine any differences in the clinical features of patients having TPN and bacteremia due to A baumannii and those due to nonbaumannii Abc (including AGS 3 and AGS 13TU). METHODS: The data of patients who had received TPN and had Abc bacteremia in Taipei Veterans General Hospital between August 1998 and December 2007 were retrospectively reviewed. The Acinetobacter isolates were identified to genomic species level. RESULTS: A total of 23 patients with A baumannii and 23 patients with nonbaumannii Abc (15 AGS 13TU and 8 AGS 3) bacteremia were identified. The two groups of the patients were comparable regarding their gender, age and APACHE II score at the onset of bacteremia. However, several clinical features were different between the two groups of the patients in the univariate analysis. Furthermore, A baumannii isolates were resistant to more classes of antibiotics than nonbaumannii Abc isolates. The multivariate analysis showed that a higher number of patients with A baumannii bacteremia had received TPN for ≥ 15 days before their onset of bacteremia [odds ratio (OR) 7.214, 95% confidence interval (CI) (1.108-46.989), p = 0.039]. Nevertheless, the 14-day (30.4% vs. 21.7%, p = 0.737) and all-cause in-hospital mortality rate (60.9% vs. 39.1%, p = 0.238) did not differ significantly between these two groups. CONCLUSION: The patients with A baumannii bacteremia demonstrated a longer timeframe in the treatment of TPN prior to the onset of bacteremia than those with nonbaumannii Abc bacteremia, however the clinical outcomes between the two groups of the patients did not differ significantly.

Comparison of microbiological and clinical characteristics based on SCCmec typing in patients with community-onset meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia.

Molecular identification methods based on the staphylococcal cassette chromosome mec (SCCmec) genotype are more reliable than clinical risk factors and demographic data for differentiating community-acquired and healthcare-associated (HCA) meticillin-resistant Staphylococcus aureus (MRSA). However, patients with community-onset (CO) MRSA infections, defined as a culture-positive sample obtained <48h after admission and from patients with HCA risk factors, have been infrequently studied. This study compared the clinical profiles of different SCCmec genotypes in this group of patients. From 2004 to 2008, the clinical profiles of 122 non-repetitive patients with CO-MRSA infections at a tertiary medical centre in Taiwan were retrospectively recorded and the molecular characteristics of the isolates were examined. The proportion of SCCmec IV/V genotypes increased from 9.5% to 35.3% from 2004 to 2008. There were no differences in demographic data, underlying diseases, invasive procedures or outcomes between the SCCmec II/III and IV/V groups, except that patients with SCCmec II/III genotypes tended to have more HCA risk factors (3.1 vs. 2.4; P=0.008). Multivariate logistic regression analysis revealed that having at least four HCA risk factors was independently associated with SCCmec II/III. The sensitivity of recovering SCCmec IV/V genotypes from patients with less than four HCA risk factors was 89.3%. This study revealed the emergence of SCCmec IV/V genotypes in CO-MRSA infections. Although the clinical characteristic boundaries between SCCmec II/III and IV/V diminished, having at least four HCA risk factors made the presence of SCCmec IV/V genotypes less likely in patients with CO-MRSA infections.

Emergence of carbapenem-resistant non-baumannii species of Acinetobacter harboring a blaOXA-51-like gene that is intrinsic to A. baumannii.

The bla(OXA-51)-like gene, originally intrinsic to Acinetobacter baumannii, had been detected in two clones of Acinetobacter nosocomialis and one clone of Acinetobacter genomic species "Close to 13TU." These bla(OXA-51)-like genes, all preceded by ISAba1, were located on plasmids that might have originated with A. baumannii. The plasmid-borne ISAba1--bla(OXA-51)-like confers a high level of carbapenem resistance and affects the accuracy of using bla(OXA-51)-like detection as a tool for differentiating A. baumannii from other Acinetobacter species.

Clinical experience with tigecycline as treatment for serious infections in elderly and critically ill patients.

BACKGROUND: Tigecycline was approved for the treatment of complicated intra-abdominal and complicated skin/skin structure infections. Because of its in vitro effectiveness for multidrug-resistant (MDR) isolates, tigecycline has been prescribed more broadly. This study evaluated tigecycline use after its first introduction in Taiwan and experience with tigecycline for the treatment of MDR Acinetobacter baumannii (MDRAB) infection, especially for ventilator-associated pneumonia. METHODS: Patients treated with tigecycline were collected retrospectively from February 2008 to July 2008 in Taipei Veterans General Hospital, a 2,900-bed tertiary care medical center in Taiwan. Patients were divided into three groups according to the indications: Group 1, Food and Drug Administration-approved indications; Group 2, health care-associated pneumonia (HAP); and Group 3, urinary tract infection, osteomyelitis, bacteremia, etc. Cases of MDRAB were also identified. RESULTS: Among 66 cases, indications for the administration of tigecycline included Food and Drug Administration-approved indications (12, 18.2%), HAP (38, 57.6%), bacteremia (3, 4.5%), catheter-related infections (3, 4.5%), urinary tract infection (4, 6.1%), osteomyelitis (4, 6.1%), and others (2, 3%). Clinical outcome was positive in 20 cases, with higher clinical success rate for Group 1 than Group 2, which may correlate with higher Sequential Organ Failure Assessment score, older age, and more frequent intensive care admission in Group 2. Of the microbiologically evaluable cases, MDRAB predominated (33/51, 64.7%). Among infections with MDRAB (excluding pneumonia without ventilator), the clinical success rate was 12% (3/25). CONCLUSIONS: The most common indication for the prescription of tigecycline was HAP. Success rate for MDRAB infection was lower than that previously reported, possibly because of serious underlying conditions and comorbidities in our patients. Because of limited choices, physicians should weigh the risk and benefit for prescribing tigecycline.

Predictors of mortality in surgical patients with Acinetobacter baumannii bacteremia.

BACKGROUND: Acinetobacter baumannii has emerged as an important pathogen of nosocomial infection. The aim of this study was to evaluate the predictors of poor outcome in surgical patients with A baumannii bacteremia. METHODS: We retrospectively recruited a total of 50 patients who developed A baumannii bacteremia within 2 weeks after surgery during a 113-month period. The primary outcome for this study was all-cause 14-day mortality. Clinical and laboratory data, antimicrobial susceptibility, treatment, and Sequential Organ Failure Assessment (SOFA) score were evaluated as possible predictors of outcome. RESULTS: The 14-day mortality was 20% and there was no association between type of surgery and mortality. The SOFA score was the only independent predictor of 14-day mortality after adjustment for other variables. The calibration was acceptable (Hosmer-Lemeshow χ(2) = 3.65, p = 0.72) and the discrimination was good (area under the receiver operating characteristic curve: 0.80 ± 0.07, 95% confidence interval, 0.67-0.94). We found that a SOFA score ≥ 7 was a significant predictor of 14-day mortality in surgical patients with A baumannii bacteremia. CONCLUSIONS: The SOFA score assessed at the onset of bacteremia is a reliable tool for predicting 14-day mortality in surgical patients with A baumannii bacteremia.

Prediction of patient outcome from Acinetobacter baumannii bacteremia with Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation (APACHE) II scores.

OBJECTIVE: Acinetobacter baumannii is an important nosocomial pathogen associated with a high mortality rate. However, no objective and quantitative severity scores are available for the severity stratification. We aimed to assess the effectiveness of SOFA and APACHE II scores calculated at the onset of bacteremia in predicting the mortality of patients with A. baumannii bacteraemia. PATIENTS AND METHODS: A total of 110 patients with A. baumannii bacteremia were included in this retrospective study during the 40-month study period. Information including clinical and laboratory data was collected. RESULTS: Multivariate analysis showed that both SOFA and APACHE II scores were independent outcome predictors after adjustment for other parameters. Goodness-of-fit was good for SOFA and APACHE II, and both models displayed excellent AUROCs (SOFA: 0.83 ± 0.06, APACHE II: 0.82 ± 0.08 in predicting 14-day mortality; SOFA: 0.85 ± 0.04, APACHE II: 0.81 ± 0.04 in predicting in-hospital mortality). There was no significant difference in the predictions of the two scoring systems, and the scores were highly correlated (r(2)=0.724, p <0.001). We found that SOFA >8, APACHE II >29 and SOFA >7, APACHE II >23 are associated with significantly higher 14-day and in-hospital mortality rates, respectively. CONCLUSION: SOFA and APACHE II scores assessed at the onset of bacteremia are reliable risk stratifying tools in predicting 14-day and in-hospital mortality in A. baumannii bacteremia. For ease of calculation, the use of SOFA rather than APACHE II score to predict mortality of A. baumannii bacteremia might have clinical application.

Polymerase chain reaction assay for the detection of Acinetobacter baumannii in endotracheal aspirates from patients in the intensive care unit.

BACKGROUND: We aim to evaluate the efficacy of polymerase chain reaction (PCR) to detect Acinetobacter baumannii in endotracheal aspirates. METHODS: Endotracheal aspirates and clinical data were collected from patients who were admitted to the intensive care unit of Taipei Veterans General Hospital between April 1 and August 31 in 2006. Bacterial isolates from endotracheal aspirate cultures were phenotypically identified as Acinetobacter calcoaceticus-A baumannii complex using the API ID 32GN system. The presence of A baumannii in the aspirate was also directly detected by multiplex PCR. RESULTS: Ten of the 114 endotracheal aspirate cultures were positive for A calcoaceticus-A baumannii complex, and only nine of the isolates were confirmed as A baumannii by the multiplex PCR. Direct PCR detection showed that 40 (35.1%) of the endotracheal aspirates were positive for A baumannii. Using positive culture of A baumannii as the gold standard, the sensitivity of direct PCR detection was 100% (6 of 6), the specificity was 70.4% (38 of 54), the positive predictive value was 27.3% (6 of 22), and the negative predictive value (NPV) was 100% (38 of 38) among patients with A baumannii pneumonia. Among patients with A baumannii colonization, the sensitivity of direct PCR detection was 100% (3 of 3), the specificity was 70.6% (36 of 51), the positive predictive value was 16.7% (3 of 18), and the NPV was 100% (36 of 36). CONCLUSION: Direct PCR detection of A baumannii in endotracheal aspirates has a high sensitivity and NPV as compared with culture-based methods. Further studies are needed to determine the clinical applicability of this rapid detection test.

Erythema multiforme caused by Treponema pallidum in a young patient with human immunodeficiency virus infection.

Erythema multiforme (EM) is usually caused by drug reactions or virus infection. We report a case of secondary syphilis presenting as EM in an HIV-infected patient, proved by immunohistochemical staining, which is rare in the literature. It is valuable to determine the etiology of EM to optimize treatment.