The Level of Medical Technologists' Perception of and Compliance with Hospital Infection Control Guidelines / 병원감염관리

BACKGROUND: The propose of this study was to identify the level of medical technologists' perception of and compliance with hospital infection control guidelines. METHODS: A questionnaire survey was conducted for 65 medical technologists working at three university hospitals in Seoul and Kyunggi areas. The questionnaire was composed of 34 questions on the general characteristics (14 items) of individual responders and about infection control guidelines (20 items). Their response was marked on the basis of 5 points for each question. RESULTS: The mean scores of the perception of and compliance with the infection control guidelines were 4.62+/-0.34 and 3.85+/-0.42, respectively. The female technologists scored significantly higher than did the male counterparts in the participation level of the infection control guidelines (P<0.05). The medical technologists who had participated in an infection control educational program were more likely than those who had not to show a higher compliance level on the infection control guidelines (P<0.05). CONCLUSION: The study demonstrated that the development of infection control educational programs for medical technologists and a supportive policy of the hospital administration should contribute to the prevention of nosocomial infections.

Susceptibility of Clinical Isolates of Acinetobacter baumannii and Pseudomonas aeruginosa to Colistin and Polymyxin B in Korea

BACKGROUND: The emergence of multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa has become a major problem. The use of nontraditional agents such as colistin and polymyxin B have been tried. The purpose of this study was to evaluate the colistin and polymyxin B susceptibility of A. baumannii and P. aeruginosa isolates in Korea. MATERIALS AND METHODS: According to susceptibility of ceftazidime and imipenem, selected 93 isolates of A. baumannii and 99 isolates of P. aeruginosa were collected from 5 university hospitals in Korea. Susceptibility to colistin and polymyxin B was tested using the reference broth microdilution method. RESULTS: The rates of other beta-lactams, aminoglycosides, and ciprofloxacin susceptibility were high (58-100%, 50-100%, and 75-100%, respectively) in ceftazidime- and imipenem-susceptible isolates but were low (< or =31%, < or =47%, and < or =18%, respectively) in ceftazidime- or imipenem-resistant isolates (P<0.05). Colistin and polymyxin B displayed a nearly identical spectrum of activity, exhibiting excellent potency against A. baumannii (MIC50/90, 1/2 microgram/mL) and P. aeruginosa (MIC50/90, 1/1 microgram/mL). Only one of the A. baumannii isolates was resistant to colistin (MIC, 4 microgram/mL), but the isolate was susceptible to polymyxin B (MIC, 2 microgram/mL). CONCLUSION: In Korea, no A. baumannii and P. aeruginosa isolates were resistant to both colistin and polymyxin B. These data suggested that polymyxins may be alternative drugs for multidrug-resistant A. baumannii and P. aeruginosa isolates.

Susceptibility of Clinical Isolates of Acinetobacter baumannii and Pseudomonas aeruginosa to Colistin and Polymyxin B in Korea

BACKGROUND: The emergence of multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa has become a major problem. The use of nontraditional agents such as colistin and polymyxin B have been tried. The purpose of this study was to evaluate the colistin and polymyxin B susceptibility of A. baumannii and P. aeruginosa isolates in Korea. MATERIALS AND METHODS: According to susceptibility of ceftazidime and imipenem, selected 93 isolates of A. baumannii and 99 isolates of P. aeruginosa were collected from 5 university hospitals in Korea. Susceptibility to colistin and polymyxin B was tested using the reference broth microdilution method. RESULTS: The rates of other beta-lactams, aminoglycosides, and ciprofloxacin susceptibility were high (58-100%, 50-100%, and 75-100%, respectively) in ceftazidime- and imipenem-susceptible isolates but were low (< or =31%, < or =47%, and < or =18%, respectively) in ceftazidime- or imipenem-resistant isolates (P<0.05). Colistin and polymyxin B displayed a nearly identical spectrum of activity, exhibiting excellent potency against A. baumannii (MIC50/90, 1/2 microgram/mL) and P. aeruginosa (MIC50/90, 1/1 microgram/mL). Only one of the A. baumannii isolates was resistant to colistin (MIC, 4 microgram/mL), but the isolate was susceptible to polymyxin B (MIC, 2 microgram/mL). CONCLUSION: In Korea, no A. baumannii and P. aeruginosa isolates were resistant to both colistin and polymyxin B. These data suggested that polymyxins may be alternative drugs for multidrug-resistant A. baumannii and P. aeruginosa isolates.

Evaluation of Vitek and Disk Diffusion Susceptibility Testing of Enterobacteriaceae against Piperacillin-Tazobactam and Methicillin-Resistant Staphylococcus aureus against Trimethoprim-Sulfamethoxazole / 대한임상미생물학회지

BACKGROUND: The aim of this study was to evaluate the Vitek system and the disk diffusion method for susceptibility testing of Enterobacteriaceaeagainst piperacillin-tazobactam (TZP) and methicillin-resistant Staphylococcus aureus (MRSA) against trimethoprim-sulfamethoxazole (SXT)using the broth microdilution method as the reference. METHODS: Using the Vitek system and the disk diffusion method, we tested 96 isolates of Enterobacteriaceae (48 Escherichia coli, 26 Klebsiella pneumoniae, 8 Serratia marcescens, 6 Enterobacter cloacae, 2 E. aerogenes, 2 K. oxytoca, 2 Citrobacter freundii, 2 Pantoea agglomerans) and 61 isolates of MRSA for susceptibity against TZP and SXT, respectively; the broth microdilution of National Committee for Clinical Laboratory Standards was used as the reference method. RESULTS: In the susceptibility testing of Enterobacteriaceae against TZP, Vitek system yielded 10 (10%) minor errors, and the disk diffusion method one (1%) very major and 13 (14%) minor errors. For the MRSA against SXT, the rate of categorical agreement between the reference method and the Vitek or the disk diffusion method was both 100%. The rates of agreement between the reference method and the Vitek system in term of MICs (within +/-1 dilution) were 93% and 98% in the susceptibility testing of Enterobacteriaceae against TZP and MRSA against SXT, respectively. CONCLUSION: Both Vitek system and disk diffusion method showed an acceptable level of accuracy for the susceptibility test of Enterobacteriaceaeagainst TZP and MRSA against SXT.

Isolation of Klebsiella Oxytoca Clinical Isolate Producing AmpC beta-lactamase, DHA-1 / 대한임상미생물학회지

BACKGROUND: Klebsiella oxytoca strain exhibiting an unusual inducible beta-lactam resistance phenotype was isolated from a wound specimen of a patient at a university hospital in August 2002. The isolate was resistant to ampicillin, ampicillin-sulbactam, cephalothin, cefoxitin, and demonstrated reduced inhibition zone diameters for ceftazidime in combination with clavulanate versus those for ceftazidime when tested alone. METHODS: Antimicrobial susceptibilities were tested using the Etest and disk diffusion method. AmpC beta-lactamase production was determined by modified Hodge test. The disk antagonism method was used to detect inducibility of beta-lactamase. Conjugation experiments were performed by the filter mating method using the recipient Escherichia coli J53 Azir strain. PCR and DNA sequencing of DHA-specific PCR products were tested. RESULTS: The double disk synergy test was negative and the modified Hodge test was positive for the K. oxytoca isolate. Antagonism was observed between cefoxitin and oxyimino-cephalosporins. Sequence analysis of the DHA-specific PCR products revealed that they were identical to the amino acid sequence of the DHA-1 beta-lactamase. Transfer of the resistance by conjugation experiments was successful. CONCLUSIONS: We found a plasmid-mediated DHA-1 beta-lactamase-producing K. oxytoca possessing an unusual inducible beta-lactam resistance phenotype was found in a university hospital in Korea. The resistance phenotype was conferred by DHA-1 encoded by a self-transferable plasmid.

Detection and Occurrence of Extended-Spectrum beta-Lactamase-Producing Citrobacter freundii, Enterobacter spp., Proteus spp., and Serratia marcescens Isolates / 임상검사와정도관리

BACKGROUND: The occurrence of extended-spectrum beta-lactamases (ESBLs) in enterobacteria that possess inducible Bush group 1 chromosomal beta-lactamases is being increasingly reported worldwide. The current National Committee for Clinical Laboratory Standards documents do not indicate the tests that should be used for the detection of ESBLs in Enterobacteriaceae except Klebsiella spp. and Escherichia coli. We determined the occurrence and detection of ESBL-producing Enterobacteriaceae isolates. METHODS: One hundred fifty-six consecutive, non-repeated isolates of Citrobacter freundii, Enterobacter spp., Proteus spp., and Serratia marcescens were collected. These isolates were performed broth microdilution antimicrobial susceptibility test, Vitek ESBL detection test, and double disk synergy (DDS) test. All the DDS-positive strains were tested PCR amplification of the blaTEM and blaSHV alleles. RESULTS: S. marcescens (27.3%) was the most frequently isolated ESBL producers followed by E. cloacae (23.8%), E. aerogenes (18.2%), C. freundii (13.3%), and P. mirabilis (8.3%). Among the total of 30 isolates that were considered ESBL producers, the Vitek ESBL detection test was positive for 26 (86.7%) strains. The genotypes of ESBLs were predominently SHV type (10 isolates) followed by others (8 isolates), SHV and TEM (7 isolates), and TEM type (5 isolates). CONCLUSIONS: Our findings indicate that 19.2% of all Enterobacteriaceae except E. coli and Klebsiella spp. tested produced ESBLs. The Vitek ESBL detection test seems to be a useful test to identify ESBL-producing strains of C. freundii, Enterobacter spp., Proteus spp., and S. marcescens isolates.

Single Clone of Toxic Shock Syndrome Toxin 1-Producing Methicillin-Resistant Staphylococcus Aureus Isolated from a Neonatal Intensive Care Unit Patients / 대한임상미생물학회지

BACKGROUND: Six babies infected with Staphylococcus aureus occurred in a neonatal intensive care unit (NICU) over a period of 2 months, which was successfully controlled with the aid of moleculartyping of the isolates. METHODS: We examined the staphylococcal toxins, mecA and tst gene PCR, and repetitive-element PCR (rep-PCR) typing in S. aureus isolated from the clinical specimens of infected babies, nasal swabs of the patients and medical personnels in a NICU, and environmental equipments. RESULTS: Among all S. aureus isolates tested, they were toxic shock syndrome toxin 1 (TSST-1)- producing methicillin-resistant S. aureus (MRSA) who have mecA and tst gene, and one identical rep- PCR pattern all, except 3 MRSA isolated from the nasal swabs of 2 non-infected patients and 1 medical personnel. CONCLUSIONS: It was demonstrated that TSST-1 producing MRSA became epidemic in the NICU as a result of the spread of a single clone.

Methicillin-Resistant Staphylococcus aureus Infections in Intensive Care Unit (ICU) Patients: Relation to Nasal Carriage of Patients or ICU Personnels / 대한임상미생물학회지

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is the most common nosocomial pathogen, which is particularly prevalent in intensive care units (ICUs). We performed this study to investigate the modes of transmission of MRSA and the role of nasal carriage of MRSA to subsequent MRSA infection in ICU. METHODS: From September to November 1997, all patients admitted for more than two days to the ICU were studied prospectively. Nasal swabs were obtained at admission and weekly during the ICU stay. Surveillance cultures of nares of the ICU personnels were done. Molecular typing was performed with repetitive sequence-based PCR (rep-PCR). RESULTS: At ICU admission 34 patients (21.0%: 19 MSSA, 15 MRSA) were MRSA nasal carrier, while 126 patients were free of nasal colonization. During the ICU stay 12 (9.5%: 3 MSSA, 9 MRSA) of the 126 noncolonized patients became nasal carriers (P <0.05). S. aureus infections (all MRSA) were documented in 14 (15 isolates, 8.6%) of the total 162 patients. S. aureus infections were significantly higher for those patients who were nasal carriers at ICU admission than for those found to be initially negative (P <0.05). Two different type (A, 7 isolate; B, 8 isolates) of rep-PCR patterns were identified. All four nasal and seven clinical isolates from the patients, and four nasal isolates from the ICU personnels were mixed with A and B patterns, respectively. CONCLUSION: Nasal colonization was related to the increased incidence of MRSA infections. Patients or ICU personnels who were nasal colonized with MRSA seemed to be a major source for transmission of MRSA in the ICU.