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Although most Klebsiella pneumoniae liver abscesses have been reported to be monomicrobial, clinical outcomes have not been compared between antimicrobial therapy with and without anti-anaerobic coverage. A propensity score-matched cohort study was conducted using the 731 cases of K. pneumoniae liver abscess. Clinical outcomes were compared between a group discontinuing anti-anaerobic agents after K. pneumoniae identification and a group continuing. A total of 170 cases were matched at a 1:1 ratio using their propensity to discontinue anti-anaerobic agents. The McNemar's test showed no difference in mortality rates (1.8% for discontinuation versus 2.3% for continuation; P = 1.00) or relapse (1.8% versus 2.9%; P = 0.73) between groups. Early discontinuation of anti-anaerobic agents had no association with treatment failure by means of the generalized estimating equation model (odds ratio 0.48; P = 0.14) and the Kaplan-Meier method (P = 0.85) in matched groups. Early discontinuation of anti-anaerobic agents does not affect the clinical outcomes of patients with K. pneumoniae liver abscess., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Emergence of polymyxin resistance in carbapenem-resistant isolates is a great concern in clinical settings because it may mean the end of treatment options against Gram-negative bacterial infections. Polymyxin-nonsusceptible and -susceptible Pseudomonas aeruginosa isolates resistant to carbapenems and harboring bla(IMP-6) were alternatively isolated from a patient. In vitro antimicrobial susceptibility testing, multilocus sequence typing, and pulsed-field gel electrophoresis were performed. Metallo-β-lactamase genes such as bla(IMP), bla(VIM), bla(SPM), bla(GIM), and bla(SIM) and bla(OXA-50) were detected by polymerase chain reaction. Sequences of 2-component systems, PmrAB and PhoPQ, were also determined. All showed ST235 and the same pulsotype. Amino acid substitutions were identified in PmrB and PhoP from polymyxin-nonsusceptible isolates. Colistin exposure might be associated with the recovery of polymyxin-nonsusceptible isolates in this patient., (Copyright © 2012 Elsevier Inc. All rights reserved.)

We investigated the characteristics of 48 carbapenem-resistant Acinetobacter baumannii isolates collected from 5 tertiary care hospitals in Korea by multilocus sequencing typing, pulsed-field gel electrophoresis, and polymerase chain reaction amplification of the antimicrobial resistance determinants. We identified 2 distinct main clones of carbapenem-resistant A. baumannii isolates, which showed different antimicrobial resistance profiles and are also differentiated by the kinds of oxacillinase (OXA) carbapenemases and Acinetobacter-derived cephalosporinase (ADC) beta-lactamases. One main clone, ST22:A, had 27 carbapenem-resistant isolates (56.3%), showed high polymyxin B and colistin resistances (33.3% and 37.0%, respectively), and contained both bla(OXA-51-like) and bla(OXA-23-like) genes and the bla(ADC-29) or bla(ADC-30) gene. In contrast, the other main clone, ST28:B, included 15 isolates (31.3%), showed complete susceptibilities to polymyxin B and colistin, and contained only the bla(OXA-51-like) gene and bla(ADC-31) or bla(ADC-32) genes. The distribution of these main carbapenem-resistant A. baumannii clones did not relate to locality, indicating that they are widespread in Korean hospitals. In addition, we found new types of PER beta-lactamases, PER-6.

A total of 59 vancomycin-resistant Enterococcus faecium (VREF) clinical isolates were collected from 8 Korean hospitals for 2 months in 2004. They were investigated by genotyping for glycopeptide resistance, multilocus sequence typing (MLST), esp repeat profiling, and structural analysis of Tn1546-like element. Nine of 59 VREF isolates (15.3%) from 5 hospitals in Korea showed VanB phenotype, but they contained vanA gene. MLST and esp repeat profiling indicated that E. faecium isolates with VanB phenotype and vanA genotype occurred from independent genetic background except 3 isolates from 1 hospital. Structural analysis of Tn1546 also showed that these isolates were not clonally related. Data showed a relatively high frequency of VREF isolates with incongruence between phenotype and genotype for glycopeptide resistance in Korean hospitals.

In vitro activities of ertapenem and 11 other comparator agents were tested against 1025 isolates of respiratory pathogens collected from 12 Asian countries. Resistance rate to ertapenem was 1.2% in 602 isolates of Streptococcus pneumoniae (MIC(50), 0.06/MIC(90), 1 microg/mL). Ertapenem was also very active against penicillin-, ciprofloxacin-, erythromycin-, and multidrug-resistant pneumococcal isolates (resistance rate: 3.5%, 2.7%, 1.9%, and 2.7%, respectively). Ertapenem-resistant pneumococcal isolates were found only in Vietnam and Korea. Ertapenem resistance was not found in methicillin-susceptible Staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis, and Klebsiella pneumoniae, including extended-spectrum beta-lactamase producers. In vitro data suggest that ertapenem could be a useful treatment option for community-acquired pneumonia.

In vitro activities of tigecycline were compared with 15 other comparator agents against recent clinical isolates of respiratory pathogens (623 Streptococcus pneumoniae, 105 Staphylococcus aureus, 92 Klebsiella pneumoniae, and 84 Haemophilus influenzae isolates) collected from 11 Asian countries. All isolates of S. pneumoniae from Asian countries were susceptible to tigecycline regardless of penicillin susceptibility with MIC90 of