BackgroundWhether the combination of antimicrobial therapy is a factor in mortality in Pseudomonas aeruginosa bacteremia remains to be elucidated. This study investigated the risk factors for mortality in P. aeruginosa bacteremia patients and the influence of adequate antimicrobial therapy and combination therapy on clinical outcomes.MethodsThis retrospective study analyzed data of 234 patients with P. aeruginosa bacteremia at a 1,200-bed tertiary teaching university hospital in South Korea between January 2010 and December 2012. Factors associated with mortality were determined. Mortality was compared in patients with adequate empirical and targeted combination therapy, and monotherapy, and inappropriate therapy.ResultsA total of 141 (60.3%) patients were given appropriate empirical antibiotic treatment (combination therapy in 38 and monotherapy in 103). Among 183 patients (78.2%) who finally received appropriate targeted treatment, 42 had combination therapy and 141 had monotherapy. The percentage of patients receiving empirical combination therapy was slightly, but not significantly higher, in the survivor group than in the nonsurvivor group (17.0% [31/182] vs. 13.5% [7/52], p = 0.74). A similar tendency was demonstrated for targeted combination therapy (19.8% [36/182] vs. 11.5% [6/52], respectively; p = 0.31). However, in a subgroup analysis of data from patients (n = 54) with an absolute neutrophil count less than 500/mm3, the patients who had appropriate empirical or targeted combination therapy showed better outcomes than those who underwent monotherapy or inappropriate therapy (p < 0.05). Mechanical ventilation (odds ratio [OR], 6.93; 95% confidence interval [CI], 2.64–18.11; p = 0.0001), the use of a central venous catheter (OR, 2.95; 95% CI, 1.35–6.43; p = 0.007), a high Acute Physiology and Chronic Health Evaluation II score (OR, 4.65; 95% CI, 1.95–11.04; p = 0.0001), and presence of septic shock (OR, 2.91; 95% CI, 1.33–6.38; p = 0.007) were independent risk factors for 14-day mortality.ConclusionsDisease severity was a critical factor for mortality in our patients with P. aeruginosa bacteremia. Overall, combination therapy had no significant effect on 14-day mortality compared with monotherapy. However, appropriate combination therapy showed a favorable effect on survival in patients with febrile neutropenia.

BackgroundWe evaluated the coincidence rate between Vitek MS system (bioMérieux, France) and Vitek 2 in identifying uropathogens directly from urine specimens.MethodsUrine specimens submitted to our microbiology laboratory between July and September 2013 for Gram staining and bacterial culture were analyzed. Bacterial identification was performed by using the conventional method. Urine specimens showing a single morphotype by Gram staining were processed by culturing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Of 2,370 urine specimens, 251 showed a single morphotype on Gram staining, and among them, 202 were available for MALDI-TOF MS.ResultsIn these 202 specimens, colony growth was observed in 189 specimens, and 145 specimens had significant growth of single-colony morphotype in culture. One hundred and ten (75.9%) of them had colony counts of ≥105 colony-forming units (CFU)/mL and included 71 enteric gram-negative bacteria (GNB), 5 glucose-non-fermenting GNB, 9 gram-positive cocci (GPC), and 25 yeasts. Furthermore, 70 (98.6%), 3 (60.0%), 4 (44.4%), and 5 (20.0%), respectively, of these were correctly identified by Vitek MS. Thirty-one specimens (21.4%; 11 GNB, 7 GPC, 12 yeasts, and 1 gram-positive bacillus) had colony counts of 104-105 CFU/mL. Four specimens (2.8%) yielded colony counts of 103-104 CFU/mL.ConclusionsVitek MS showed high rate of accuracy for the identification of GNB in urine specimens (≥105 CFU/mL). This could become a rapid and accurate diagnostic method for urinary tract infection caused by GNB. However, for the identification of GPC and yeasts, further studies on appropriate pre-treatment are warranted.

BackgroundWe investigated the rates of fecal transmission of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) and carbapenem-resistant Enterobacteriaceae (CRE) among patients admitted to intensive care units (ICUs).MethodsFrom June to August 2012, rectal cultures were acquired from all patients at ICU admission. For patients not carrying ESBL-E or CRE at admission, follow-up cultures were performed to detect acquisition. A chromogenic assay was used to screen for ESBL-E and CRE. Bacterial species identification and antibiotic susceptibility tests were performed using the Vitek 2 system (bioMérieux, France). ESBL genotypes were determined by PCR, and clonal relatedness of the isolates was assessed by pulsed-field gel electrophoresis.ResultsOut of 347 ICU admissions, 98 patients were found to be carriers of ESBL-E (28.2%, 98/347). Follow-up cultures were acquired from 91 of the patients who tested negative for ESBL-E at admission; the acquisition rate in this group was 12.1% (11/91), although none was a nosocomial transmission. For CRE, the prevalence of fecal carriage was 0.3% (1/347), and the acquisition rate was 2.9% (4/140). None of the CRE isolates were carbapenemase-producers.ConclusionsThe high prevalence of ESBL-E carriage on admission (28.2%), coupled with rare nosocomial transmission and the very low carriage rate of CRE (0.3%), challenge the routine use of active surveillance in non-epidemic settings. Nevertheless, passive surveillance measures, such as rapid and accurate screening of clinical specimens, will be critical for controlling the spread of CRE.

BackgroundWe evaluated the reliability and accuracy of the combined use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial identification and Vitek 2 antimicrobial susceptibility testing (AST) for bacteria from positive blood culture bottles.MethodsDirect identification and AST were performed in parallel to the standard methods in monomicrobial positive blood culture bottles. In total, 254 isolates grown on aerobic and/or anaerobic bottles were identified with MALDI-TOF Vitek MS (bioMérieux, France), and 1,978 microorganism/antimicrobial agent combinations were assessed. For isolates from anaerobic bottles, an aliquot of the culture broth was centrifuged, washed, and filtered through a nylon mesh. For isolates from aerobic/pediatric bottles, a lysis step using 9.26% ammonium chloride solution and 2% saponin solution was included.ResultsThe overall correct identification rate was 81.8% (208/254) and that for gram-positive/gram-negative isolates was 73.9%/92.6%, respectively, and it was 81.8%, 87.6%, and 57.9% for isolates from aerobic, anaerobic, and pediatric bottles, respectively. Identification was not possible in 45 cases, and most of these isolates were streptococci (N=14) and coagulase-negative staphylococci (N=11). Misidentification occurred only in one case. Compared with standard methods, direct AST showed 97.9% (1,936/1,978) agreement with very major error of 0.25%, major error of 0.05%, and minor error of 1.8%.ConclusionsThis simple and cost-effective sample preparation method gives reliable results for the direct identification and AST of bacteria. For the identification of streptococci and coagulase-negative staphylococci, the method should be further improved.

Betafoam may result not only in desirable rapid regulation of exudation but also antimicrobial activity with minimal cytotoxicity to host cells that are key requirements for wound healing.

We investigated the molecular genotypes of ciprofloxacin-resistant Klebsiella pneumoniae and their characteristics according to the genetic lineages. For 160 K. pneumoniae collected in 2013, ciprofloxacin minimum inhibitory concentrations (MICs) were determined by agar dilution method. The genotypes of ciprofloxacin-resistant K. pneumoniae isolates were determined by multilocus sequence typing (MLST) and wzi gene typing. The presence of plasmid-mediated resistance determinants [qnrA, qnrB, qnrS, aac(6')-Ib-cr, blaCTX-M, and blaSHV] was investigated. The gyrA and parC genes were sequenced. Fifty-seven isolates showed ciprofloxacin resistance. By MLST, four major sequence types (STs) or clonal complexes (CCs), that is, ST307, CC11, CC147, and ST15, were found and the two most prevalent STs were ST307 (14/57, 24.6%) and ST11 (12/57, 21.1%). By wzi gene sequencing, 46 of the 57 isolates could be differentiated. All the ST307 isolates had an identical wzi sequence and harbored qnrB. The majority of them harbored aac(6')-Ib-cr (85.7%) and CTX-M-15 (92.9%). In contrast, 12 ST11 isolates were divided into five sublineages by wzi sequence and qnrB, qnrS, and aac(6')-Ib-cr were carried by nine, seven, and three isolates, respectively. They harbored SHV-type extended-spectrum β-lactamase more frequently than CTX-M-15 (nine and four isolates, respectively). The prevalence of CTX-M-15, qnrB1, and aac(6')-Ib-cr was significantly higher in ST307 than in ST11 (p=0.003, p=0.000, and p=0.002, respectively). Both clones had identical amino acid substitution in gyrA (S83I) and parC (S80I). K. pneumoniae ST307 and ST11 were the two most common clones, and the ST307 isolates were highly homogeneous, suggesting their recent emergence.

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A substantial portion of ESBL-producing isolates were susceptible to cefepime and ceftazidime by using the CLSI and EUCAST breakpoints. Unfortunately, the error rates of the two automated susceptibility systems were not acceptable for cefepime and ceftazidime.