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Background Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea. Methods We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern. Results The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively. Conclusions There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.

Background: Salmonella is an important pathogen that causes gastroenteritis and sepsis in humans. Recently, changes in serotype prevalence and an increase in antimicrobial resistance have been reported. This study investigated the distribution of Salmonella serotypes and determined the antimicrobial susceptibility of various strains. Methods: We collected 113 Salmonella isolates other than Salmonella serotype Typhi from 18 university hospitals in 2015. The serotypes were identified by Salmonella antisera O and H according to the Kauffman White scheme. Antimicrobial susceptibility tests for 12 antibiotics were performed using the disk diffusion method or E-test. Results: We identified 22 serotypes. Serotype group B (44.2%) was the most common, followed by groups C (34.5%) and D (21.2%). Salmonella I 4,[5],12:i:- (23.0%), S. Enteritidis (16.8%), and S. Typhimurium (12.4%) were the most common species. Resistance rates for ampicillin, chloramphenicol, ceftriaxone, and trimethoprim/sulfamethoxazole were 46.9%, 18.5%, 8.8%, and 5.3%, respectively. The intermediate resistance rate to ciprofloxacin was 29.2%. Six isolates were extended-spectrum β-lactamase (ESBL) producers, including 5 blaCTX-M-15 and 1 blaCTX-M-55. Conclusion: There have been changes in the serotype prevalence and antimicrobial resistance of Salmonella in Korea, with a high prevalence of CTX-M 15-positive strains. Continuous monitoring of Salmonella serotypes and antimicrobial resistance is warranted. (Ann Clin Microbiol 2019;22:55-60)

This study compared the accuracy of a new MALDI-TOF mass spectrometry system, ASTA MicroIDSys system, with that of MALDI Biotyper system for the identification of reference and clinical bacterial and yeast strains. The identification accuracy of the 2 systems was compared using a total of 406 strains comprising 142 aerobic and 180 anaerobic bacterial strains and 84 yeast strains. The genus and species identification rates were 98.0% and 89.4% using MicroIDSys and 96.1% and 89.4% using Biotyper, respectively. The species identification rates of MicroIDSys and Biotyper for aerobic bacteria were 93.0% and 97.2%, respectively, and those for anaerobic bacteria were 85.6% and 81.7%, respectively. The accuracy of yeast identification at the species level was 91.7% using MicroIDSys and 92.9% using Biotyper. These findings indicate that MicroIDSys could be useful for the accurate identification of bacteria and yeast in clinical microbiology laboratories.

Various mechanisms underlying antimicrobial resistance in Acinetobacter baumannii have been reported. There exists controversy regarding the relationships between efflux pump activity, biofilm formation, and antimicrobial resistance in A. baumannii. In this study, we investigated the relative expression of RND efflux pump genes, H33342 efflux activity, and biofilm-forming activity in 120 A. baumannii clinical isolates, examined their potential relationships with one another, and then statistically analyzed their effects on antibiotic resistance. High adeB expression and high H33342 efflux activity were correlated with low biofilm-forming activity. High adeB expression was significantly correlated with resistance to tigecycline and cefotaxime, but not with the multidrug resistance (MDR) phenotype. Importantly, only high adeJ expression was significantly correlated with the MDR phenotype, and was observed to be correlated with resistance to various antibiotics. However, we found no significant correlation between adeJ expression and biofilm-forming activity. Further, adeG expression was found to not be correlated with antibiotic resistance and biofilm-forming activity. The results of multivariate analysis showed that adeB overexpression and high H33342 efflux activity are related to biofilm-forming activity, and only adeJ overexpression is significantly associated with the MDR phenotype, highlighting the importance of adeJ overexpression.

We evaluated the ability of the Filamentous Fungi Library 1.0 of the MALDI-TOF MS Biotyper system to identify 345 clinical Aspergillus isolates from 11 Korean hospitals. Compared with results of the internal transcribed spacer region sequencing, the frequencies of correct identification at the species-complex level were 94.5% and 98.8% with cutoff values of 2.0 and 1.7, respectively. Compared with results of β-tubulin gene sequencing, the frequencies of correct identification at the species level were 96.0% (cutoff 2.0) and 100% (cutoff 1.7) for 303 Aspergillus isolates of five common, non-cryptic species, but only 4.8% (cutoff 1.7) and 0% (cutoff 2.0) for 42 Aspergillus isolates of six cryptic species (identifiable by β-tubulin or calmodulin sequencing). These results show that the MALDI Biotyper using the Filamentous Fungi Library version 1.0 enables reliable identification of the majority of common clinical Aspergillus isolates, although the database should be expanded to facilitate identification of cryptic species.

Objective Aural irrigation using antiseptic solutions can be an effective medical treatment of chronic suppurative otitis media (CSOM) owing to the increasing prevalence of antibiotic-resistant CSOM infections. In the present study, we compared the antimicrobial activities of 100% Burow's solution, 50% Burow's solution, 2% acetic acid, vinegar with water (1:1), and 4% boric acid solution against methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible S. aureus (MSSA), quinolone-resistant Pseudomonas aeruginosa (QRPA), and quinolone-susceptible P. aeruginosa (QSPA) in vitro. Methods We examined the antimicrobial activities of five antiseptic solutions against MRSA, MSSA, QRPA, and QSPA. The antimicrobial activities of the solutions were calculated as a percentage of the surviving microorganisms by dividing the viable count in each antiseptic solution with that in control. The time (D10 value) required for each of the five solutions to inactivate 90% of the microorganism population was also investigated. Results Burow's solution exhibited the highest antimicrobial activity and the lowest D10 value against MRSA, MSSA, QRPA, and QSPA, followed by 2% acetic acid, vinegar with water (1:1), and 4% boric acid solution. Conclusion Our results indicate that Burow's solution has the most potent activity against bacteria including antibiotic-resistant strains. Twofold dilution of the solution is recommended to avoid ototoxicity.

Background Acinetobacter baumannii infections are difficult to treat owing to the emergence of various antibiotic resistant isolates. Because treatment options are limited for multidrug-resistant (MDR) A. baumannii infection, the discovery of new therapies, including combination therapy, is required. We evaluated the synergistic activity of colistin, doripenem, and tigecycline combinations against extensively drug-resistant (XDR) A. baumannii and MDR A. baumannii. Methods Time-kill assays were performed for 41 XDR and 28 MDR clinical isolates of A. baumannii by using colistin, doripenem, and tigecycline combinations. Concentrations representative of clinically achievable levels (colistin 2 µg/mL, doripenem 8 µg/mL) and achievable tissue levels (tigecycline 2 µg/mL) for each antibiotic were used in this study. Results The colistin-doripenem combination displayed the highest rate of synergy (53.6%) and bactericidal activity (75.4%) in 69 clinical isolates of A. baumannii. Among them, thedoripenem-tigecycline combination showed the lowest rate of synergy (14.5%) and bacteri-cidal activity (24.6%). The doripenem-tigecycline combination showed a higher antagonistic interaction (5.8%) compared with the colistin-tigecycline (1.4%) combination. No antagonism was observed for the colistin-doripenem combination. Conclusions The colistin-doripenem combination is supported in vitro by the high rate of synergy and bactericidal activity and lack of antagonistic reaction in XDR and MDR A. baumannii. It seems to be necessary to perform synergy tests to determine the appropri-ate combination therapy considering the antagonistic reaction found in several isolates against the doripenem-tigecycline and colistin-tigecycline combinations. These findings should be further examined in clinical studies.

Acinetobacter baumannii infection is a significant health problem worldwide due to increased drug resistance. The limited antimicrobial alternatives for the treatment of severe infections by multidrug-resistant A. baumanniiA. baumannii A. baumannii(MDRAB) make the search for other therapeutic options more urgent. Linalool, the major oil compound in Coriandrum sativum, was recently found to have high antibacterial activity against A. baumannii. The purpose of this study was to investigate the synergistic effect of linalool and colistin combinations against MDRAB and extensively drug-resistant A. baumanniiA. baumannii A. baumannii(XDRAB). A total of 51 strains of A. baumanniiA. baumannii A. baumanniiclinical isolates, consisting of 10 MDRAB and 41 XDRAB were tested. We determined the minimum inhibitory concentration (MIC) of linalool for the test strains using the broth microdilution method and searched for interactions using the time-kill assay. The time-kill assay showed that the linalool and colistin combination displayed a high rate of synergy (92.1%) (by synergy criteria 2), low rate of indifference (7.8%), and a high rate of bactericidal activity (74.5%) in the 51 clinical isolates of A. baumannii. The synergy rates for the linalool and colistin combination against MDRAB and XDRAB were 96% and 92.1%, respectively. No antagonism was observed for the linalool and colistin combination. The combination of linalool and colistin showed a high synergy rate, which may be beneficial for controlling MDRAB infections. Therefore, this combination is a good candidate for in vivo studies to assess its efficacy in the treatment of MDRAB infections.

8p11 myeloproliferative syndrome (EMS) is a rare disease characterized by myeloproliferative neoplasm (MPN) associated with eosinophilia and T or B lymphoblastic lymphoma/leukemia. EMS is defined by molecular disruption of the FGFR1 gene at the 8p11-12 chromosome locus, and various partner genes are associated with FGFR1 gene translocation or insertion. The different partner-FGFR1 fusion genes are associated with slightly different disease phenotypes. The present patient showed T lymphoblastic lymphoma in a cervical lymph node, involvement of malignant lymphoma in the skin, and MPN bone marrow morphology with peripheral monocytosis. Chromosome analysis of the patient showed t(1;8)(q25;p11.2). To our knowledge, only 2 cases of EMS with translocation of t(1;8)(q25;p11.2) have been previously reported. Including this case, all 3 cases with EMS with t(1;8)(q25;p11.2) showed MPN bone marrow morphology and peripheral monocytosis. These findings support that t(1;8)(q25;p11.2) is associated with peripheral monocytosis in EMS patients. Of the 2 cases of EMS with t(1;8)(q25;p11.2) which were previously reported, FGFR1 rearrangement was not confirmed in 1 case. Similarly, FGFR1 rearrangement in the present case was not detected by fluorescence in situ hybridization or reverse transcription-polymerase chain reaction. Further study is needed to identify other techniques that could be used to demonstrate FGFR1 rearrangement.

Objective To assess whether this compound (ALH-L1005) is conceivably an effective agent in protecting against cochlear damage induced by LPS. Materials and methods Tube formation using human umbilical vein endothelial cell (HUVEC) and matrix metalloproteinase (MMP)-9 inhibition assay was performed. 24 guinea pigs were randomly divided into three groups. Intratympanic instillation of LPS ( n = 8) as negative control, instillation of oxytetracycline 1 h after LPS as positive control ( n = 8), and intratympanic instillation of ALH-L1005 ( n = 8) 1 h after LPS were considered experimental group. Evaluation by auditory brainstem response (ABR) measurement, cochlear blood flow, and blood–labyrinth barrier (BLB) permeability were performed. Cochlear hair cells were observed by field emission-scanning electron microscopy (FE-SEM). MMP-9 activation was measured by gelatin zymography. Results For HUVEC, the tube formation was suppressed in a dose dependant manner. ALH-L1005 inhibited the MMP-9 activity prominently. It also attenuated the elevation of LPS-induced hearing threshold shift and recovery of CBF. By FE-SEM, cochlear hair cells could be preserved in experimental group. ALH-L1005 significantly reduced the BLB opening compared to LPS group. Active MMP-9 expression could be detected in the LPS group. In contrast to ALH-L1005 group, active MMP-9 expression was not detected. Conclusion Our results conclude that ALH-L1005 showed a protective effect in the cochlear lateral wall damage induced by LPS.

BACKGROUND National surveillance of antimicrobial resistance becomes more important for the control of antimicrobial resistance and determination of treatment guidelines. We analyzed Korean Antimicrobial Resistance Monitoring System (KARMS) data collected from 2013 to 2015. METHODS Of the KARMS participants, 16 secondary or tertiary hospitals consecutively reported antimicrobial resistance rates from 2013 to 2015. Data from duplicate isolates and institutions with fewer than 20 isolates were excluded. To determine the long-term trends, previous KARMS data from 2004 to 2012 were also considered. RESULTS The prevalence of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium from 2013 to 2015 was 66-72% and 29-31%, respectively. The resistance rates of Escherichia coli to cefotaxime and cefepime gradually increased to 35% and 31%, respectively, and fluoroquinolone resistance reached 48% in 2015. The resistance rates of Klebsiella pneumoniae to cefotaxime, cefepime, and carbapenem were 38-41%, 33-41%, and

To compare the identification accuracies of VITEK 2 (bioMérieux), MicroScan (Siemens Healthcare), and Phoenix (Becton Dickinson), microbial identification was performed on 160 clinical isolates and 50 reference strains on each of these 3 systems, using the appropriate identification kit provided by each system. Of the 142 clinical isolates that were identified at the species level, VITEK 2, MicroScan, and Phoenix correctly identified 93.7%, 82.4%, and 93.0%, and incorrectly identified 2.1%, 7.0%, and 0%, respectively. In the reference strain tests, VITEK 2, MicroScan, and Phoenix correctly identified 55.3%, 54.4%, and 78.0% of the reference strains at the species level and incorrectly identified 10.6%, 13.0%, and 6.0% of the reference strains, respectively. In conclusion, the identification rate of VITEK 2, Phoenix, and MicroScan was high or acceptable on clinical isolates. Phoenix showed a significantly higher performance than VITEK 2 or MicroScan in identifying the reference strains.

Background and objective β-Tricalcium phosphate (TCP) has good biodegradability and osteoconductivity as a scaffold material for bone tissue engineering. Both block and granular forms are available; however, it has been associated with risk of infection and exposure. To this end, the study evaluated the effect of piperacillin-tazobactam coated β-TCPs for mastoid obliteration in otitis media. Materials and methods Ten guinea pigs were divided into the experimental (piperacillin-tazobactam coated β-TCP granules, n = 5) and control groups (uncoated β-TCP granules, n = 5). After mastoid obliteration, transtympanic injection with a saline suspension of lipopolysaccharide established inflammation. The animals were sacrificed 5 weeks later. Tissue sections were stained with hematoxylin and eosin and examined. Results Encapsulation and formation of fibrous capsule by foreign material in the bulla were not evident. The histological evaluation did not reveal inflammatory cells and fibrosis in the piperacillin-tazobactam coated β-TCP group. In contrast, the control group showed numerous inflammatory cells around the implanted uncoated β-TCP granules and incomplete new bone formation. Conclusion β-TCP is an effective carrier material for piperacillin-tazobactam. The use of piperacillin-tazobactam coated β-TCP may be optimal for mastoid obliteration.

BACKGROUND JAK2 genetic variations have been described in a high proportion of patients with BCR/ABL1-negative myeloproliferative neoplasms (MPN). This study was designed to analyze the frequencies of JAK2 V617F and exon 12 variations, and their correlations with clinical characteristics of Korean patients with BCR/ABL1-negative MPN. METHODS We examined a total of 154 patients with BCR/ABL1-negative MPN that included 24, 26, 89, and 15 patients with polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET), and unclassified myeloproliferative neoplasms (MPNU), respectively. We performed allele-specific PCR to detect V617F in all BCR/ABL1-negative patients, and performed direct sequencing to detect exon 12 variations in 47 V617F-negative MPN patients. JAK2 c.1641+179_183del5 variation was detected by restriction fragment length polymorphism assay in 176 healthy subjects. RESULTS JAK2 V617F was detected in 91 patients (59.1%): PV (91.6%), PMF (46.2%), ET (52.8%), and MPNU (66.7%). In V617F-negative MPN patients, no mutations were found in exon 12. The c.1641+179_183del5 was detected in 68.1% of V617F-negative MPN patients and 45.4% of healthy subjects (P=0.008). JAK2 V617F was closely correlated with age and leukocytosis in BCR/ABL1-negative MPN patients (P

Background We developed a new disposable anaerobic culture system, namely, the Quick anaero-system, for easy culturing of obligate anaerobes. Methods Our system consists of 3 components: 1) new disposable anaerobic gas pack, 2) disposable culture-envelope and sealer, and 3) reusable stainless plate rack with mesh containing 10 g of palladium catalyst pellets. To evaluate the efficiency of our system, we used 12 anaerobic bacteria. We prepared 2 sets of ten-fold serial dilutions of the 12 anaerobes, and inoculated these samples on Luria-Bertani (LB) broth and LB blood agar plate (LB-BAP) (BD Diagnostic Systems, USA). Each set was incubated in the Quick anaero-system (DAS Tech, Korea) and BBL GasPak jar with BD GasPak EZ Anaerobe Container System (BD Diagnostic Systems) at 35-37 degrees C for 48 hr. The minimal inoculum size showing visible growth of 12 anaerobes when incubated in both the systems was compared. Results The minimal inoculum size showing visible growth for 2 out of the 12 anaerobes in the LB broth and 9 out of the 12 anaerobes on LB-BAP was lower for the Quick anaero-system than in the BD GasPak EZ Anaerobe Container System. The mean time (+/-SD) required to achieve absolute anaerobic conditions of the Quick anaero-system was 17 min and 56 sec (+/-3 min and 25 sec). Conclusions The Quick anaero-system is a simple and effective method of culturing obligate anaerobes, and its performance is superior to that of the BD GasPak EZ Anaerobe Container System.

Background : Group A rotavirus is a major cause of severe diarrhea in children throughout the world. For the proper management of rotavirus infections, it will be helpful to know their clinical characteristics according to the G and P genotypes of the infecting virus. Methods : The diarrheal stool specimens from patients hospitalized in Chosun University Hospital during 2002-2003 were tested for rotavirus by Dipstick 'Eiken' Rota kit. Rotavirus antigen-positive stool specimens were analyzed for group A rotavirus by RT-PCR, and the group A-positive PCR products were genotyped for P and G types by PCR. Results : Among the 119 specimens analyzed for genotypes, the predominant strain was genotype G4P[6] (51.3%), followed by G2P[4] (19.3%), G1P[8] (7.6%), G3P[8] (5.0%), and G9P[8] (4.2%). To examine the characteristics of each rotavirus genotype, a clinico-epidemiological study was performed for 100 patients whose medical records were available. The frequencies of diarrhea, vomiting, dehydration, and fever; the rates of nosocomial infection and transfer from other hospitals; and the mean severity scores were significantly different among the patients infected with different types of rotavirus. Especially, patients with G4P[6] type were more likely than those infected with other genotypes to show the following distinct features: Most patients showed milder symptoms and were neonates transferred from other obstetric hospitals and 68.4% of the cases were nosocomial infection. G4P[6] strains were isolated almost all along the year. The mean severity scores of patients infected by G4P[6], G2P[4], G1P[8], G3P[8], and G9P[8] strains were 6.8, 9.5, 8.0, 9.0, and 10.8, respectively. Conclusions : Many features of rotavirus infections including the epidemic period, rate of nosocomial infection, age and severity of symptoms were different according to the genotypes of the infecting virus.

The 5th year KONSAR surveillance in 2001 was based on routine test data at 30 participating hospitals. It was of particular interest to find a trend in the resistances of enterococci to vancomycin, of Enterobacteriaceae to the 3rd generation cephalosporin and fluoroquinolone, and of Pseudomonas aeruginosa and acinetobacters to carbapenem. Resistance rates of Gram-positive cocci were: 70% of Staphylococcus aureus to oxacillin; 88% and 16% of Enterococcus faecium to ampicillin and vancomycin, respectively. Seventy-two percent of pneumococci were nonsusceptible to penicillin. The resistance rates of Enterobacteriaceae were: Escherichia coli, 28% to fluoroquinolone; Klebsiella pneumoniae, 27% to ceftazidime, and 20% to cefoxitin; and Enterobacter cloacae,or =40% to cefotaxime and ceftazidime. The resistance rates of P. aeruginosa were 21% to ceftazidime, 17% to imipenem, and those of the acinetobacters wereor =61% to ceftazidime, aminoglycosides, fluoroquinolone and cotrimoxazole. Thirty-five percent of non-typhoidal salmonellae were ampicillin resistant, and 66% of Haemophilus influenzae were beta-lactamase producers. Notable changes over the 1997-2001 period were: increases in vancomycin-resistant E. faecium, and amikacin- and fluoroquinolone-resistant acinetobacters. With the increasing prevalence of resistant bacteria, nationwide surveillance has become more important for optimal patient management, for the control of nosocomial infection, and for the conservation of the newer antimicrobial agents.

Dear Editor, This paper reports valuable parameters, soluble transferrin receptor-ferritin index (sTfR-F) and estimated body iron (EBI), to make the diagnosis of iron deficiency anemia (IDA) in chronic diseases. Based on the textbook definition [1], anemia of chronic diseases do not include anemia caused by bone marrow replacement, blood loss, renal failure, hepatic diseases, hemolysis, and endocrine deficiencies and so those diseases were excluded in this study. In addition, to obtain a high efficiency in detecting IDA from chronic diseases, the patients were limited to those with “select” chronic diseases excluding pernicious anemia, parvovirus B19, and hematologic malignancies. The “select” chronic diseases were arbitrary made for this study. Those patients were admitted to Chosun University Hospital. One hundred seventy-seven patients with select chronic diseases, including 27 patients with chronic infections, 71 patients with chronic diseases, and 79 patients with non-hematologic malignancies, were studied. The male– female ratio was variable and the ages ranged from 18– 81 years. All patients were divided into three disease groups according to the criteria for anemia and IDA (below described). Thus, there were 48 patients with non-anemic state in select chronic diseases (NAsCD group), 110 patients with anemia of select chronic diseases (AsCD group), and 19 patients with IDA in select chronic diseases (IDA-sCD group). The criterion for anemia was a hemoglobin 17%, and concurrent microcytic hypochromic RBC with anisocytosis on the peripheral blood smear. The patients were further divided into four iron status groups according to the grade of iron granules in bone marrow particles as follows: increased iron group showing many iron granules, adequate iron group showing some iron granules, decreased iron group showing a few iron granules, and deficient iron group showing no iron granules. The numbers of patients in the deficient iron group were three (6.25%) of 48 patients in NAsCD, 11 (10.0%) of 110 patients in AsCD, and 18 (94.74%) of 19 patients in IDA-AsCD (Table 1). Hematologic parameters (Hb and CHr), serum ferritin, and sTfR were determined on an ADVIA 120 automated hematology analyzer (Siemens, Tarrytown, NY, USA), an Axsym analyzer (Abbott Laboratories, Abbott Park, IL, USA), and a BNII nephelometer (Dade Behring, Marburg, Germany), Ann Hematol (2009) 88:913–915 DOI 10.1007/s00277-008-0668-4

Since accurate identification of species is necessary for proper treatment of Acinetobacter infections, we compared the performances of 4 bacterial identification methods using 167 Acinetobacter clinical isolates to identify the best identification method. To secure more non-baumannii Acinetobacter (NBA) strains as target strains, we first identified Acinetobacter baumannii in a total of 495 Acinetobacter clinical isolates identified using the VITEK 2 system. Because 371 of 495 strains were identified as A. baumannii using gyrB multiplex 1 PCR and blaOXA51-like PCR, we performed rpoB gene sequencing and 16S rRNA gene sequencing on remaining 124 strains belonging to NBA and 52 strains of A. baumannii. For identification of Acinetobacter at the species level, the accuracy rates of rpoB gene sequencing, 16S rRNA gene sequencing, gyrB multiplex PCR, and the VITEK 2 were 98.2%, 93.4%, 77.2%, and 35.9%, respectively. The gyrB multiplex PCR seems to be very useful for the detection of ACB complex because its concordance rates to the final identification of strains of ACB complex were 100%. Both the rpoB gene sequencing and the 16S rRNA gene sequencing may be useful in identifying Acinetobacter.

Background The aim of this study was to determine the yearly prevalence and genotype distribution of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae collected over a 3-yr period in Gwangju, Korea. Methods Clinical isolates of E. coli and K. pneumoniae collected at Chosun University Hospital from September 15, 2005 to September 14, 2008 were evaluated. Antimicrobial susceptibility testing was performed using the Vitek II system (bioMerieux, USA) and agar dilution methods. Screening for ESBL and AmpC β-lactamase genes was performed using PCR amplification of plasmid DNA followed by direct sequencing of the PCR products. Results The percentage of ESBL-producing isolates was 12.6% (196/1,550) for E. coli and 26.2% (294/1,121) for K. pneumoniae. The ESBL gene sequencing results showed that the most prevalent ESBL types were CTX-M (93.5%) and SHV (12.9%) in E. coli, and SHV (73.2%) and CTX-M (46.3%) in K. pneumoniae. The most common ESBL in E. coli was CTX-M-15-like, followed by CTX-M-14-like, SHV-2a-like, and SHV-12-like. The most prevalent ESBL type in K. pneumoniae was SHV-12, followed by CTX-M-14-like and CTX-M-15-like. Fifty-one percent (21/41) of ESBL-producing K. pneumoniae with ESBL types verified by sequencing also had DHA-1-like AmpC β-lactamases. However, none of the ESBL-producing E. coli was positive in the AmpC β-lactamase PCR analysis. Conclusions In this study, the most common types of class A ESBLs identified were CTX-M-15-like in E. coli and SHV-12-like in K. pneumoniae.

Typhoid fever is a systemic intracellular infection caused by Salmonella enterica serotype Typhi. The emergence and spread of nalidixic acid-resistant S. Typhi (NARST) is challenging for clinicians in many countries owing to the lack of suitable treatment options. The aim of this study was to identify in vitro synergistic combinations of antibiotics against S. Typhi. In vitro time–kill studies were performed on three clinical NARST isolates and one type strain of nalidixic acid-susceptible S. Typhi (NASST) ATCC 9992 with ciprofloxacin, cefotaxime and azithromycin in various combinations. The combination of ciprofloxacin (0.012–0.375 μg/mL) and cefotaxime (0.063–0.125 μg/mL) against all three NARST strains and the NASST strain was significantly more effective in vitro in reducing bacterial counts by ≥3 log 10 colony-forming units at 24 h and showed synergistic effects. Combination therapy with ciprofloxacin and cefotaxime might be the treatment of choice for patients with typhoid fever. The combination of a fluoroquinolone and a β-lactam, which are directed against different targets, may improve efficacy compared with a fluoroquinolone alone and may reduce the chance of fluoroquinolone-resistant mutants emerging in patients with severe typhoid fever.

An unusual class 1 integron was identified that carries an IS26-disrupted aadA1 gene cassette (designated as 'integron-IS26') in an imipenem-resistant Acinetobacter baumannii (IRAB) outbreak strain. DNA sequencing revealed that integron-IS26 contained two gene cassettes, the aac(6')-Im cassette and a peculiar aadA1 cassette that was disrupted by IS26 (disrupted aadA1 cassette). Southern blotting localised integron-IS26 to the chromosome. Nested polymerase chain reaction (PCR) was performed to define the frequency of integron-IS26 in five groups of bacteria. Nested PCR identified integron-IS26 in 19 (73.1%) of 26 clinical outbreak strains of IRAB, 10 (100%) of 10 IRAB isolated from environmental cultures, 3 (13.0%) of 23 imipenem-susceptible A. baumannii (ISAB) non-outbreak strains, 1 (3.6%) of 28 netilmicin- and tobramycin-resistant A. baumannii and none of the netilmicin- and tobramycin-resistant Pseudomonas aeruginosa. In conclusion, we have identified a novel class I integron that carries the aac(6')-Im cassette and an IS26-disrupted copy of aadA1 (integron-IS26) in most IRAB outbreak strains and in a few ISAB non-outbreak control strains. Integron-IS26 is located chromosomally.

Background : We noticed an abrupt increase in the isolation of Stenotrophomonas maltophilia from bronchoalveolar lavage (BAL) specimens collected at Chosun University Hospital. We performed surveillance cultures in order to identify the source of what appeared to be a pseudo-outbreak. Methods : To investigate a possible nosocomial outbreak of S. maltophilia, we performed culture of 11 environmental specimens obtained from a bronchoscopy room and two bronchoscopes. Pulsed- field gel electrophoresis (PFGE) was used to examine the genetic relatedness among the strains of S. maltophilia recovered from BAL specimens of 3 patients and 1 environmental sample, as well as 9 unrelated strains of S. maltophilia as a control. Results : During a 7 day-period in March 2006, S. maltophilia was isolated from the BAL specimens of 7 of 13 (54%) patients, compared to only 5 of 188 (2.6%) patients during the 6-month period prior to that period. S. maltophilia was isolated from 1 of the 11 environmental samples, which was obtained from a fiberoptic bronchoscope suction channel. All 7 patient isolates and one environmental isolate exhibited similar antibiotic susceptibility patterns. PFGE analysis of the genomic DNA from epidem- ic strains demonstrated an identical banding pattern, whereas each of epidemiologically unrelated strains showed a unique electrophoretic pattern. Conclusions : Apparently one of the hospital bronchoscopes became contaminated with S. malto- philia during a bronchoscopic procedure. It is likely that subsequent specimen contamination occurred because the bronchoscope had been inadequately cleaned and disinfected. The pseudo-outbreak was controlled successfully by removing the source of infection. (Korean J Lab Med

Comparison of the Vitek 2, API 20A, and 16s rRNA Gene Sequencing for the Identification of Anaerobic Bacteria Gyun Cheol Park, Sook Jin Jang, Min Jung Lee, Joong-Ki Kook, Min Jung Kim, Young Sook Kim, Nam Woong Yang, Hye Soo Lee, Seong Ho Kang, Geon Park, Dae Soo Moon Department of Laboratory Medicine, Research Center for Resistant Cells, Chosun University College of Medicine, Department of Oral Biochemistry, College of Dentistry, Chosun University, Departments of Radiology, Chosun University College of Medicine, Department of Microbiology, College of Medicine, Chosun University, Gwangju, Department of Laboratory Medicine, Chonbuk National University Medical School, Chonbuk National University Hospital Branch of National Culture Collection of Pathogens, Jeonju, Korea

The trend of antimicrobial resistance of bacteria isolated from patients in 30 Korean hospitals in 1999 was analyzed with a particular attention to cefotaxime- or fluoroquinolone-resistant gram-negative bacilli, imipenem-resistant Pseudomonas aeruginosa, and vancomycin-resistant enterococci. Adequacy of susceptibility testing, and any change in the frequencies of isolated species were also analyzed. The results showed that only 20% and 30% of hospitals tested the piperacillin-tazobactam and cefoxitin susceptibility of Enterobacteriaceae, respectively, only 24% of hospitals the piperacillin-tazobactam susceptibility of P. aeruginosa, and 17% of hospitals the fusidic acid susceptibility of staphylococci. Among the isolates 26.3% were glucose-nonfermenting gram-negative bacilli, and 34.7% of Enterococcus were Enterococcus faecium. Slight decline of cefotaxime-resistance rate to 20% was noted in Klebsiella pneumoniae, while fluoroquinolone-resistance rate was 68% in Acinetobacter baumannii. The ceftazidime- and imipenem-resistance rates were 17% and 18%, respectively in P. aeruginosa. The vancomycin-resistance rate of E. faecium rose significantly to 15.1%, but the rates varied significantly depending on hospitals suggesting presence of different degree of selective pressure or nosocomial spread. In conclusion, the prevalence of imipenem-resistant P. aeruginosa and the increase of vancomycin-resistant E. faecium were the particularly worrisome phenomena observed in this study.

Antimicrobial-resistant bacteria are known to be prevalent in tertiary-care hospitals in Korea. Twenty hospitals participated to this surveillance to determine the nationwide prevalence of resistance bacteria in 1997. Seven per cent and 26% of Escherichia coli and Klebsiella pneumoniae were resistant to 3rd-generation cephalosporin. Increased resistance rates, 19% of Acinetobacter baumannii to ampicillin/sulbactam, and 17% of Pseudomonas aeruginoa to imipenem, were noted. The resistance rate to fluoroquinolone rose to 24% in E. coli, 56% in A. baumannii and 42% in P. aeruginosa. Mean resistance rates were similar in all hospital groups: about 17% of P. aeruginosa to imipenem, 50% of Haemophilus influenzae to ampicillin, 70% of Staphylococcus aureus to methicillin, and 70% of pneumococci to penicillin. In conclusion, nosocomial pathogens and problem resistant organisms are prevalent in smaller hospitals too, indicating nosocomial spread is a significant cause of the increasing prevalence of resistant bacteria in Korea.