Mei-Chun Chiang

Emergence of Carbapenem-Resistant Non-baumannii Species of Acinetobacter Harboring a blaOXA-51-Like Gene That Is Intrinsic to A. baumannii

ABSTRACT The blaOXA-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 blaOXA-51-like genes, all preceded by ISAba1, were located on plasmids that might have originated with A. baumannii. The plasmid-borne ISAba1--blaOXA-51-like confers a high level of carbapenem resistance and affects the accuracy of using blaOXA-51-like detection as a tool for differentiating A. baumannii from other Acinetobacter species.

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.

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.

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-β-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.

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.

Erythema Multiforme Caused by Treponema pallidum in a Young Patient with Human Immunodeficiency Virus Infection

ABSTRACT 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.

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.