Characterization of Class 1 Integrons in Metallo-beta-lactamase-producing Pseudomonas aeruginosa / 대한임상미생물학회지

BACKGROUND: The genes of metallo-beta-lactamase (MBL), a powerful carbapenemase, are carried as a part of the mobile gene cassettes inserted into integrons playing an important role in rapid dissemination of antibiotic resistance genes among bacterial isolates. In this study, we investigated carbapenemase genes and class 1 integrons integrated into the gene cassettes in imipenem-non susceptible P. aeruginosa. METHODS: From July 2006 to March 2008, 81 consecutive, non-duplicate, imipenem-non susceptible P. aeruginosa were isolated at Chungnam National University Hospital in Chungcheong province of Korea. The modified Hodge and double disk synergy tests were conducted for the screening of carbapenemase and MBL production, respectively, and PCR and DNA sequencing were performed for the detection of carbapenemase genes and class 1 integron gene cassettes. We also employed the repetitive element sequence-based (Rep)-PCR method for an epidemiologic study. RESULTS: MBLs were detected in 13.6% (11/81) of imipenem-non susceptible P. aeruginosa. Ten isolates were found to carry blaIMP-1, whereas 1 isolate was found to carry a blaVIM-2. All of the IMP-1-producing strains harbored 4.0 kb class 1 integron containing chloramphenicol, aminoglycoside, and beta-lactam- resistant genes. However, blaIMP-1 was not detected at class 1 integron. A 2.5 kb class 1 integron harboring blaVIM-2 was detected in a VIIM-2- producing strain. One identical pattern was observed in ten IMP-1 producing strains. CONCLUSION: IMP-1 producing P. aeruginosa strains are currently distributed throughout Chungcheong province of Korea. In particular, all of the strains harbored class 1 integrons containing variant antibiotic resistance gene cassettes.

Evaluation of Two Automated Instruments for Pre-transfusion Testing: AutoVue Innova and Techno TwinStation / 대한진단검사의학회지

BACKGROUND: Despite the advances in total laboratory automation, a considerable amount of work in blood banks is still done using outdated manual methods. Some automated pre-transfusion testing instruments have recently been developed. Of these, we evaluated and compared the AutoVue Innova (Ortho, USA) and the Techno TwinStation (DiaMed AG, Switzerland). METHODS: Forward and reverse ABO/Rh typing and unexpected antibody screening and identification tests were performed on 4,628 samples using the manual method and the two automated instruments. Two different anticoagulants (EDTA and citrate) were compared in ABO/Rh typing and unexpected antibody screening tests. Titrating studies were conducted on the following 7 dilutions using 5 samples of irregular antibodies with anti-E, anti-E & -c, anti-D, and anti-Le(a) with anti-Fy(a): 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, and 1:128. The test throughput per hour, the time required to perform 1 and 100 tests, and a simulation test for total events occurring in 1 day were also measured. RESULTS: No erroneous results were reported between the two instruments and the manual method. Discrepancies observed in 10 cases (0.4%) of ABO/Rh typing were of higher intensity with AutoVue Innova than with the manual method. AutoVue Innova exhibited the highest sensitivity in the titrating study and throughput performance compared with the manual method and the Techno TwinStation. Especially in the throughput and time required to complete 100 antibody screening tests, AutoVue Innova had a 3.3- and 3.5-fold higher performance, respectively, than Techno TwinStation. CONCLUSIONS: Because both of the two fully automated instruments (AutoVue Innova and Techno TwinStation) had high levels of accuracy and performance, it is expected that use of fully automated instruments will reduce human labor, turnaround time, and operator error in the blood bank.

Dissemination of IMP-1 and OXA Type beta-Lactamase in Carbapenem-resistant Acinetobacter baumannii / 대한진단검사의학회지

BACKGROUND: Acinetobacter baumannii is an aerobic, gram-negative, glucose-nonfermenting bacterium, which has emerged as a serious opportunistic pathogen. In recent years, the increasing instance of carbapenem-resistant A. baumannii producing metallo-beta-lactamases (MBLs) or OXAtype beta-lactamases is causing a serious clinical problem. In this study, we investigated the prevalence of Ambler class A, B, and D beta-lactamases and their extended-spectrum derivatives in carbapenem-resistant A. baumannii isolates. METHODS: A total of 31 consecutive, non-duplicate, carbapenem-resistant A. baumannii were isolated from three university hospitals in the Chungcheong province of Korea. The modified Hodge and inhibitor-potentiated disk diffusion tests were conducted for the screening of carbapenemase and MBL production, respectively. PCR and DNA sequencing were performed for the detection of beta-lactamase genes. We also employed the enterobacterial repetitive intergenic consensus (ERIC)-PCR method for the epidemiologic study. RESULTS: Twenty-three of 31 isolates harbored bla(OXA-2) (51.6%), bla(OXA-23) (22.6%), bla(IMP-1) (48.4%),and bla(VIM-2) (3.2%). All of the OXA-2-producing strains also evidenced MBLs. The strains that harbored bla(OXA-23) were isolated only in hospital C, and only in a limited fashion. The ERIC-PCR pattern of the five OXA-23 strains indicated that the isolates were closely related in terms of clonality. The six strains producing IMP-1 isolated from hospital A were confirmed to be identical strains. CONCLUSIONS: A. baumannii strains harboring IMP-1 or OXA-type beta-lactamases are currently widely distributed throughout the Chungcheong province of Korea. The most notable finding in this study was that a bla(OXA-2)-producing A. baumannii harboring MBL, which has not been previously reported, can also lead to outbreaks.

Characteristics of Acquired beta-lactamase Gene in Clinical Isolates of Multidrug-resistant Pseudomonas aeruginosa / 대한임상미생물학회지

BACKGROUND: Recently, there have been reports of infections with multidrug-resistant Pseudomonas aeruginosa. To determine the mechanism of the resistance, we investigated the prevalence of Ambler class A and D beta-lactamases, their extended-spectrum derivatives, and class B and D carbapenemase in multidrug-resistant P. aeruginosa isolates. METHODS: During the period of March 2006 to May 2007, clinical isolates of multidrug-resistant P. aeruginosa were collected from patients in Chungnam National University Hospital, Daejeon, Korea. Inhibitor-potentiated disk diffusion tests were used for the screening of metallo-beta-lactamase (MBL) production. PCR and DNA sequencing were conducted for the detection of beta-lactamase genes. We also employed the enterobacterial repetitive intergenic consensus (ERIC)- PCR method for an epidemiologic study. RESULTS: A total of 37 consecutive, non-duplicate, multidrug-resistant P. aeruginosa were isolated. Twenty- nine of 37 isolates harbored blaOXA-10 (56.8%), blaOXA-2 (18.9%), and blaOXA-1 (5.4%). Only one isolate produced IMP-1, and it also harbored blaOXA-1. None harbored Ambler class A beta-lactamase or class D carbapenemase. The strains producing OXA type beta-lactamases showed a significantly higher resistance to aminoglycoside compared to non-producers. The ERIC-PCR pattern of the 19 OXA-10 producing strains indicated that the isolates were closely related in terms of clonality. CONCLUSION: OXA type beta-lactamases are the most prevalent among the acquired beta-lactamases produced by multidrug-resistant P. aeruginosa isolated at a university hospital in Chungcheong Province. Besides beta-lactam antibiotics, the strains harboring OXA type beta-lactamase showed a significantly higher resistance to aminoglycoside and qunolone.

Evaluation of the Vitek 2 Korean Antimicrobial Susceptibility Testing Cards AST N056 and AST N055 / 대한임상미생물학회지

BACKGROUND: The recently issued Korean version of antimicrobial susceptibility cards for Vitek 2 system uses an adjusted antimicrobial combination that reflects Korean clinical practice and CLSI guidelines. We evaluated the two Korean antimicrobial susceptibility testing cards for gram negative rods, AST N056 and AST N055. METHODS: The results of susceptibility tests were compared between the original and Korean cards. A number of the same antimicrobials included in the both cards were 15 in AST N041-AST N056 and 17 in AST N022-AST N055. Susceptibilities to the newly added antimicrobials, aztreonam, tobramycin, and meropenem for AST N056; and cefotaxime, levofloxacin, and minocycline for AST N055 were compared with those obtained by disc diffusion test and, in case of discrepancy, by confirmative Etest or broth dilution method. RESULTS: In comparison between AST N041 and AST N056 cards, the average discrepancy rate per strain was 0.34, minor error was 88.2%, and major error and very major error were both 5.9%. In comparison between AST N022 and AST055 cards, the average discrepancy rate per strain and very major error were 1.23 and 4.4%, respectively. The three antimicrobial agents added into AST N055 card showed highly discrepant results as a total of 49 items (44.1%) in 111 isolates were discrepant with very major error of 5.9% and major error of 2.0%. CONCLUSION: AST N056 showed acceptable results in most items including the newly added antimicrobial agents. However, in the case of AST N055 card that showed a relatively high discrepancy, other indicator antibiotics should be referred to for newly added three antimicrobials. For the antibiotics that showed a high discrepancy between the original and Korean cards, a comparison study should be performed using the standard method and clinical isolates collected in Korea.

A Case of Acute Promyelocytic Leukemia with PML/RARA Translocation Showing Familial t(9;15)(q34;q22) / 대한혈액학회지

We report the unusual case of an APL patient with a familial t(9;15)(q34;q22) and acquired t(15;17) (q22;q21). This is unique in that the patient had a constitutional abnormality with the same breakpoints as those observed in the tumor clone from the APL. It is unclear if the breakpoint, 15q22, in the constitutional aberration influenced the induction of the PML/RARA translocation in the APL. If a specific translocation in a patient with leukemia does not go away with clinical improvement, a congenital or familial chromosomal abnormality should be considered. Additional patients with similar findings are needed to understand the pathogenesis of these events.

he Performance of the Newly Released Automated Chemistry Analyzer Rx Imola / 임상검사와정도관리

BACKGROUND: The Rx Imola (Randox, UK) is newly released bench top - fully automated analyzer based on Window XP software with high-throughput (640 tests per hour with ISE) and continuous random access. We evaluated the performance of Rx Imola for the routine chemistry. METHODS: Repeatability (within-day precision), between-day precision, within-device precision, linearity, recovery rates and correlation were evaluated for 19 items including AST, ALT, ALP, GGT, total bilirubin, calcium, phosphorus, albumin, total protein, BUN, creatinine, glucose, amylase, total cholesterol, triglyceride, HDL, LDH, CK and uric acid. Commercialized quality control materials and patient's sera were used. For correlation study, 747-100 (HITACHI, Japan) and VITROS 950 (Ortho-Clinical Diagnostics, USA) were used as comparative analyzers. RESULTS: Coefficients of variation (CVs) of all items in repeatability and between-day precision study were below 5%. The linearities were statistically acceptable (R2>0.99) for all items. The recovery rates ranged from 95.7 to 105.3%. The comparison study showed high correlation between Rx Imola and 747-100 or VITROS 950. Correlation coefficients of all items were above 0.99 except HDL and albumin. CONCLUSIONS: This study showed satisfactory results in precision, linearity, recovery rates and comparison studies of Rx Imola. It was expected to be useful for routine chemistry analysis and back up, because of high performance, easy handling and small size.

Prevalence of Extended-Spectrum beta-lactamases in Escherichia coli and Klebsiella pneumoniae from Daejeon / 대한진단검사의학회지

BACKGROUND: Extended-spectrum beta-lactamases (ESBLs) are cephalosporinases that confer resistance to a wide variety of oxyimino cephalosporins and create serious therapeutic problems. Although ESBLs have been reported with increasing frequency in Korea, their prevalence and genotypic distribution in Daejeon remain unknown. This study was designed to evaluate the occurrence and genotypic distributions of ESBL-producing Escherichia coli and Klebsiella pneumoniae in Daejeon. METHODS: We tested a total of 427 isolates of E. coli and K. pneumoniae at Chungnam National University Hospital during the period from March to September 2006. ESBL production was determined by the Clinical and Laboratory Standards Institute ESBL confirmatory test; minimum inhibitory concentrations of beta-lactam antibiotics were determined by the broth dilution method. The ceftazidime or cefotaxime resistance of the ESBL-producers was transferred to azide-resistant E. coli J53 by conjugation. Searches for ESBL genes were performed by PCR amplification, and the genotypes of ESBLs were determined by direct nucleotide sequence analysis of the amplified products. The pIs of ESBL were determined by isoelectric focusing. RESULTS: The proportion of ESBL-producers was 10% of the E. coli and 28% of the K. pneumoniae isolates. The prevalence of ESBL-positive isolates was 60% in the intensive care units and 18.7% in the general wards. The most prevalent ESBL genotype in E. coli isolates was blaCTX-M and in K. pneumoniae was blaSHV-12. CONCLUSIONS: E. coli and K. pneumoniae isolates producing SHV-12 or CTX-M-type ESBLs are widespread in Daejeon.

Reference Intervals in Healthy Adults using Automatic Cell Counter Beckman Coulter LH 750 / 임상검사와정도관리

BACKGROUND: Our aim was to set reference intervals of healthy adults using Beckman Coulter LH 750 by gender and age. METHODS: The specimens were obtained from a total of 705 healthy adults (male 484, female 221), who took part in annual health-check at Chungnam National University Hospital, analyzed in total 22 parameters and compared using SPSS V10.0 program. RESULTS: Totally 16 parameters showed the Gaussian distribution with 12 in parametric method and 4 in logarithmically transformed parametric method. All acquired reference intervals were showed in Table 3, 4, 5 and 6. There were statistical significances between genders in RBC, Hgb, Hct, MCV, MCH, WBC, EO%, LY#, MO#, EO#, MPV, PDW (P<0.001), BA% (P=0.001), NE% (P=0.016), BA# (P=0.019), MO% (P=0.021) and NE# (P=0.039), between age decades in RBC, Hgb, Hct, MCV, MCH, NE%, LY% (P<0.001), LY# (P=0.002), EO%, NE# (P=0.003) and Pct (P=0.033) as well as between genders and age decades in RBC, Hct (P=0.001), Hgb (P=0.004), LY# (P=0.005), Plt (P=0.014) and MO% (P=0.017). CONCLUSIONS: This study suggested that the reference intervals of RBC and Hgb ought to be set by both genders and age decades, WBC by gender and the others by total study populations. Moreover, it need to be set the reference intervals by each laboratory for itself and to be monitored with periodic review.