Molecular Epidemiology and Characterization of Carbapenemase-Producing Enterobacteriaceae Isolated at a University Hospital in Korea during 4-Year Period / 대한임상미생물학회지

BACKGROUND: Carbapenemase-producing Enterobacteriaceae (CPE) has been increasingly reported worldwide in the past 10 years, which is an important infection control concern. Since the epidemiology and characteristics of these CPEs vary according to institutes, we aimed to characterize CPEs in a university hospital during the recent 4 years. METHODS: From October 2011 to September 2015, CPE isolates from clinical specimens and hospital surveillance cultures were collected. Carbapenem resistance was confirmed by disk diffusion method and Minimal Inhibitory Concentration (MIC) was determined by agar dilution method. Carbapenemase production was tested by double disk test using aminophenylboronic acid and dipicolic acid. PCR and sequence analysis were performed to detect bla(KPC), bla(IMP-1), bla(VIM-2), bla(NDM-1)-like genes and bla(OXA-48) gene. Pulsed-field gel electrophoresis (PFGE) and Multilocus sequence typing (MLST) were conducted for KPC-producing Klebsiella pneumoniae isolates. RESULTS: Twenty-five isolates (11%) of CPE were identified among 222 carbapenem-resistant Enterobacteriacae isolates during the study period. The most prevalent CPE was KPC-producing K. pneumonia and others were IMP-1, VIM-2, NDM-1 type and OXA-48 producing CPEs. Most of these CPEs showed resistance to carbapenems with variable MICs. The sequence types (STs) of KPC-producing K. pneumoniae were ST307 and ST11. The PFGE of ST11 and ST307 showed clonality in each group suggesting the possibility of in-hospital outbreak. CONCLUSION: The prevalence of CPE has been increasing. In our institute, KPC-producing K. pneumoniae was the most frequently isolated CPE in the recent 4 years. CPE including KPC producers can easily transfer their resistance. Therefore continuous monitoring and more intensified infection control for CPE should be considered.

The Evaluation of Recovery Rate of Neisseria gonorrhoeae in Two Bacterial Transport Swab Systems and Prevalence of Co-Infection after Delayed Transport / 대한임상미생물학회지

BACKGROUND: Neisseria gonorrhoeae infection remains prevalent, and the emergence of antimicrobial resistance has made the treatment and control of gonorrhea more difficult. Therefore, it is important to compare isolation methods and transport media to overcome gonorrhea via epidemiologic understanding and to determine co-infection rates with other sexually transmitted diseases among primary-care hospitals. In this study, we determine the recovery rate of transferred specimens according to type of transport media and co-infection rate using PCR. METHODS: Genital specimens were collected at three primary-care hospitals from January 2010 to November 2012 using transgrow media and commercial BD transport media. Culture and multiplex PCR were conducted to isolate N. gonorrhoeae. RESULTS: Among 162 specimens, 57 (35.2%) isolates were recovered, and 146 (90.1%) specimens were positive for multiplex PCR. The recovery rate was 29.9% (78/261) using transgrow media and 19.2% (50/261) using BD transport media. The most common co-infected bacteria with N. gonorrhoeae was Chlamydia trachomatis (15.8%), followed by Mycoplasma hominis (6.2%) and M. genitalium (3.4%). CONCLUSION: Under general transport conditions, the rate of recovery of N. gonorrhoeae was as low as 19.2-29.9% depending on the type of transport media, suggesting that molecular diagnostic methods are required to detect the remaining 70% of gonorrhea-infected patients. Co-infection with other sexually transmitted diseases was not rare, and other tests for accurate additional antimicrobial regimens should also be considered.

Loss of blaVIM-2 and blaIMP-1 during the Storage of Gram-Negative Bacilli, Antimicrobial Susceptibility of the Gene-Lost Strain, and Location of the Gene in the Cell / 대한임상미생물학회지

BACKGROUND: Gram-negative bacilli can be stored in cystine tryptic agar (CTA) at room temperature for over 1 year, but we experienced a loss of imipenem resistance among VIM-2-producing isolates. The aims of this study were to determine the frequency of loss of IMP-1 and VIM-2 genes during storage in CTA at room temperature and to document any change in the MIC of antimicrobial agents and the location of the gene. METHODS: Bacteria were isolated from clinical specimens at Severance Hospital collected from 1995-2000. Modified Hodge and double disk synergy tests were performed for screening of MBL-production isolates, and blaIMP-1 and blaVIM-2 were detected by PCR. Loss of resistance was tested in CTA at room temperature. PFGE and hybridization using a blaVIM-2 probe were carried out to determine the location of the VIM-2 gene. RESULTS: When VIM-2- and IMP-1-producing strains of eight P. aeruginosa and two Acinetobacter spp. were stored in CTA at room temperature, some isolates lost imipenem resistance after 3 days and 90% lost resistance after 15 weeks. Loss of resistance genes resulted in a decrease of the MIC of imipenem from 32-128 mug/mL to 0.5-8 mug/mL for P. aeruginosa, and from 32 mug/mL to 0.25-4 mug/mL for Acinetobacter spp. Hybridization of I-CeuI and S1-digested and PFGE suggested that VIM-2 genes are located on approximately 50-100 kb or 400 kb plasmids. CONCLUSION: Isolates may lose resistance genes when stored in CTA at room temperature. Therefore, it is necessary for MBL-production tests including the Modified Hodge test and double disk synergy test and detection of MBL genes.

Antimicrobial Resistance and Molecular Epidemiologic Characteristics of Neisseria gonorrhoeae Isolated from Korea in 2013 / 대한임상미생물학회지

BACKGROUND: Antimicrobial resistance of Neisseria gonorrhoeae has become a serious problem worldwide, and ceftriaxone non-susceptible isolates have been recently reported from Japan and Europe. In this study, we evaluated the antimicrobial susceptibilities and molecular epidemiological characteristics of isolates from Korea in 2013. METHODS: Sixty strains of N. gonorrhoeae were collected from Korean patients and prostitutes. Antimicrobial susceptibility was tested by the agar dilution and disk diffusion methods. N. gonorrhoeae multi-antigen sequence typing (NG-MAST) was performed in order to determine the molecular epidemiologic relatedness. RESULTS: All of isolates were non-susceptible to penicillin G and tetracycline, and the rate of ciprofloxacin-resistant isolates was 95% in 2013. The MICs of ceftriaxone were within the susceptible range for all isolates, but one isolate non-susceptible to cefixime (MIC=0.5 microg/mL) was encountered. The isolates with decreased susceptibility (MIC< or =0.12 microg/mL) to cefixime or ceftriaxone accounted for 10% and 14% of the isolates tested, respectively. In NG-MAST analysis, 40 different STs were encountered among the 59 isolates. Isolates that belonged to tbpB110 showed higher cefixime and ceftriaxone MICs (0.12-0.5 microg/mL) as well as cefixime resistance. CONCLUSION: Most of the N. gonorrhoeae isolates showed susceptibility to spectinomycin and cephalosporins. Due to the emergence of isolates that are non-susceptible to cefixime and the prevalence of isolates with the tbpB110 allele belonging to ST1407, which cause cefixime and ceftriaxone treatment failure in successful global clones of N. gonorrhoeae, a continuous nationwide antimicrobial surveillance program is required to monitor the emergence of cephalosporin resistance in N. gonorrhoeae.

Plasma Concentration of Prolactin, Testosterone Might Be Associated with Brain Response to Visual Erotic Stimuli in Healthy Heterosexual Males

OBJECTIVE: Many studies have showed that excess or lack of sexual hormones, such as prolactin and testosterone, induced the sexual dysfunction in humans. Little, however, is known about the role of sexual hormones showing normal range in, especially, the basal state unexposed to any sexual stimulation. We hypothesized sexual hormones in the basal state may affect sexual behavior. METHODS: We investigated the association of the sexual hormones level in the basal hormonal state before visual sexual stimulation with the sexual response-related brain activity during the stimulation. Twelve heterosexual men were recorded the functional MRI signals of their brain activation elicited by passive viewing erotic (ERO), happy-faced (HA) couple, food and nature pictures. Both plasma prolacitn and testosterone concentrations were measured before functional MR scanning. A voxel wise regression analyses were performed to investigate the relationship between the concentration of sexual hormones in basal state and brain activity elicited by ERO minus HA, not food minus nature, contrast. RESULTS: The plasma concentration of prolactin in basal state showed positive association with the activity of the brain involving cognitive component of sexual behavior including the left middle frontal gyrus, paracingulate/superior frontal/anterior cingulate gyri, bilateral parietal lobule, right angular, bilateral precuneus and right cerebellum. Testosterone in basal state was positively associated with the brain activity of the bilateral supplementary motor area which related with motivational component of sexual behavior. CONCLUSION: Our results suggested sexual hormones in basal state may have their specific target regions or network associated with sexual response.