Assessment of the Synergistic Effect of Seven Antimicrobial Combinations on Extensively DrugResistant Acinetobacter baumannii Strains / 대한임상미생물학회지

Background@#To solve the difficulty in determining the appropriate treatment regimen for patients infected with extensively drug-resistant Acinetobacter baumannii (XDRAB), it is necessary to develop various strategies to increase the therapeutic effect of antimicrobial agents. The purpose of this study was to select the treatment combination showing the greatest antimicrobial effect among seven candidate antimicrobial substances. @*Methods@#Seven strains of XDRAB were used in this study. The composition of the treatment consisted of colistin as the base and one of the seven antimicrobial substances, doripenem, minocycline, tigecycline, linezolid, fusidic acid, vancomycin, or alyteserin E4K peptide. The interaction between the drugs in each combination was evaluated by measuring the synergy rates using time-kill analysis. @*Results@#The synergy rates of the seven combinations tested in the time-kill assay in this study were as follows, in descending order from the combination with the highest synergy rate: colistin + minocycline (57.1%), colistin + alyteserin E4K (50.0%), colistin + tigecycline (42.9%), colistin + vancomycin (28.6%), colistin + doripenem (14.3%), colistin + fusidic acid (14.3%), and colistin + linzolid (0%). None of the combinations showed antagonism. The three combinations showing bactericidal activity and the rates of their bactericidal activity were colistin + alyteserin E4K combination (33.3%), colistin + minocycline (14.3%), and colistin + vancomycin (14.3%). @*Conclusion@#The colistin + minocycline and colistin + alyteserin E4K treatment combinations, which showed high synergy rates, can be considered as promising candidates for future in vivo experiments evaluating combination therapies.

Development of a Two Triplex Real-Time Polymerase Chain Reaction for Rapid Detection of Six Carbapenemase Genes in Enterobacteriaceae

ObjectivesCarbapenem resistance is a serious clinical and public health threat. Carbapenemase can confer carbapenem resistance, and most carbapenemase genes are plasmid encoded so resistance can easily spread. In this study, we aimed to develop a novel system based on the TaqMan platform for the rapid detection of 6 clinically prevalent carbapenemase genes: Klebsiella pneumoniae carbapenemase, New Delhi metallo-β-lactamase, oxacillinase, imipenem-hydrolyzing, Verona integron-encoded metallo-β-lactamase, and Guiana extended-spectrum β-lactamase.MethodsThe triplex assay was verified by testing genomic DNA of 6 carbapenemase-producing Klebsiella pneumoniae. It was validated with a blinded panel of 310 Enterobacteriaceae isolates, including 225 carbapenemase-producers and 85 non-producers, by direct colony triplex real-time polymerase chain reaction (PCR). The real-time PCR was performed using the ABI 7500 fast instrument (Applied Biosystems, CA, USA) and specific primers for each carbapenemase target were designed to include modified peptide-nucleic acid oligonucleotides.ResultsNo amplification was detected among the negative samples. The result showed 100% concordance with the genotypes previously identified. The entire assay, including DNA extraction and real-time PCR, was completed within 2 hours.ConclusionThe newly developed triplex real-time PCR assay was useful for the rapid, accurate and simultaneous detection of 6 carbapenemase genes in Enterobacteriaceae, suggesting its potential to allow an early decision on the appropriate treatment, management, and prevention of the spread of resistant infections in hospitals.

Role of Efflux Pump Gene adeIJK to Multidrug Resistance in Acinetobacter baumannii Clinical Isolates / 대한임상미생물학회지

BACKGROUND: The emergence of multidrug-resistant Acinetobacter baumannii as a nosocomial pathogen is one of the major public health problems. The aim of this study was to evaluate the role of an efflux pump gene adeJ for the multidrug resistance of A. baumannii clinical isolates.METHODS: Two groups (MDRAB and SAB) of A. baumannii clinical isolates were studied. The SAB group consisted of strains that did not meet the criteria of MDRAB and were susceptible to more categories of antibiotics than MDRAB. Antimicrobial susceptibility results obtained by VITEKII system were used in data analysis and bacterial group allocation. We performed real-time reverse transcription PCR to determine relative expression of adeJ. We compared relative expression of adeJ in comparison groups by considering two viewpoints: i) MDRAB and SAB groups and ii) susceptible and non-susceptible groups for each antibiotic used in this study.RESULTS: The mean value of relative expression of adeJ of MDRAB and SAB groups was 1.4 and 0.92, respectively, and showed significant difference (P=0.002). The mean values of relative expression of adeJ of susceptible and non-susceptible groups to the antibiotics cefepime, ceftazidime, ciprofloxacin, imipenem, meropenem, tigecycline, piperacillin/tazobactam, ticarcillin/clavulanic acid, trimethoprim/sulfamethoxazole, piperacillin, and gentamicin showed statistically significant differences.CONCLUSION: The overexpression of adeIJK might contribute to the multi-drug resistance in A. baumannii clinical isolates. Further, the overexpression of adeIJK might be one of the factors contributing to the resistance to numerous antibiotics.

Distribution of adeG, adeB, adeE, adeY, abeM, and adeJ Efflux Pump Genes in Clinical Isolates of Acinetobacter Species from Korea

BACKGROUND: The aim of the present study was to determine the frequency of six efflux pump genes in Acinetobacter clinical isolates collected from South Korean hospitals. METHODS: In this study, we used a total of 339 Acinetobacter strains, comprising 279 Acinetobacter calcoaceticus–Acinetobacter baumannii (ACB) complex and 60 non-ACB complex strains. We performed specific PCR assays to detect adeG, adeB, adeE, adeY, abeM, and adeJ, transporter genes of the multidrug efflux pumps AdeFGH, AdeABC, AdeDE, AdeXYZ, AbeM, and AdeIJK, respectively. RESULTS: Frequencies of six efflux pump genes varied according to the species of Acinetobacter. Frequencies of adeE, abeM, and adeJ between A. baumannii group and A. nosocomialis group were found to be significantly different. Significant differences were found in the frequencies of adeB, adeE, adeY, and adeJ among the susceptible A. baumannii (SAB), multidrug-resistant A. baumannii (MDRAB), and extensively drug-resistant A. baumannii (XDRAB) groups within the 154 strains of A. baumannii. The frequencies of efflux pump genes in imipenem-susceptible and imipenem-nonsusceptible groups were significantly different for adeB, adeY, and adeJ. The frequencies of efflux pump genes in ciprofloxacin-susceptible and ciprofloxacin-nonsusceptible groups were significantly different for adeB and adeY. No significant difference was found in the frequency of efflux pump genes among groups sampled from different regions of Korea, across 86 strains of A. baumannii collected in 2012. CONCLUSIONS: The frequencies of six efflux pump genes obtained in this study demonstrate the fundamental epidemiological feature of efflux pump genes in Korean Acinetobacter clinical isolates.

MCR1 and KPC2 Co-producing Klebsiella pneumoniae Bacteremia: First Case in Korea

Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-KP) has been disseminating nationwide due to clonal spread and is taking a serious action at the national level in Korea. The mobilized colistin resistance (MCR1) gene confers plasmid-mediated resistance to colistin and is known to be capable of horizontal transfer between different strains of a bacterial species. We have experienced a fatal case of the patient who developed MCR1-possessing, ST307/Tn4401a[blaKPC2] K. pneumonia bacteremia in the community of non-capital region after being diagnosed as pancreatic cancer with multiple liver metastases and treated in the capital region. The ST307/Tn4401a[blaKPC2] K. pneumonia was the most commonly disseminated clone in Korea. Our strain is the first MCR1 and KPC2 co-producing K. pneumonia in Korea and our case is the critical example that the multi-drug resistant clone can cause inter-regional spread and the community-onset fatal infections. Fortunately, our patient was admitted to the intensive care unit on the day of visit, and the contact precaution was well maintained throughout and KPC-KP was not spread to other patients. The high risk patients for KPC-KP need to be screened actively, detected rapidly and preemptively isolated to prevent outbreak of KPC-KP. Inter-facility communications are essential and the nationwide epidemiologic data of KPC-KP should be analyzed and reported regularly to prevent spread of KPC-KP. The prompt identification of species and antimicrobial susceptibilities for successful treatment against KPC-KP should be emphasized as well.

In Vitro Interactions of Antibiotic Combinations of Colistin, Tigecycline, and Doripenem Against Extensively Drug-Resistant and Multidrug-Resistant Acinetobacter baumannii

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 microg/mL, doripenem 8 microg/mL) and achievable tissue levels (tigecycline 2 microg/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.

Characterization of Endoplasmic Reticulum Stress and Apoptosis in Macrophages Infected with Mycobacterium tuberculosis Isolates from Korea Patients

Apoptosis is an important host defense mechanism against mycobacterial infection. Recent reports suggest that links between apoptosis and endoplasmic reticulum (ER) stress are critical for the regulation of mycobacterial survival; however, the exact regulatory mechanisms are not well known. In this study, we isolated 20 Mycobacterium tuberculosis (Mtb) clinical strains from Korean patients and examined ER stress-mediated apoptosis in Mtb-infected macrophages. Most Mtb strains increased the rates of apoptosis and production of ER stress-sensing molecules in mouse macrophages, similar to Mtb H37Rv infection. Moreover, the intracellular survival of Mtb clinical isolates in macrophages was similar to that of H37Rv. Our data suggest that infection with Mtb downregulated MCP-1 and MCPIP. The regulation of MCPIP may decrease ROS production, leading to a reduction in ER stress-mediated apoptosis.

The Influence of Sleep Apnea Syndrome on Cognitive Functions in Patients with REM Sleep Behavior Disorder

OBJECTIVES: We investigated the effects of sleep apnea syndrome (SAS) on cognitive functions in patients with REM sleep behavior disorder (RBD). We also studied correlations between sleep variables related with SAS and parameters of cognitive function tests. METHODS: Twenty two RBD patients with SAS and 20 RBD patients without SAS participated in the study. The diagnoses of RBD and SAS were confirmed on polysomnography. All the participants performed neuropsychological tests by the Korean version of the Consortium to Establish a Registry for Alzheimer's disease (CERAD-K) Assessment Packet. RESULTS: There were no differences between two groups in age and sex, education, body mass index, and results of the Beck depression inventory (BDI) and the Epworth sleepiness scale (ESS). No difference was found in any of parameters of the CERAD-K between two groups. The cognitive functions were not correlated with BDI, ESS, or variables related with SAS. CONCLUSION: SAS had no influence on cognitive functions of RBD patients. The result could be explained by negligible effects of SAS on cognitive functions among aged population and no difference in daytime sleepiness between the RBD patients with and without SAS.

The Correlation between Parenting Behaviors, Object Relation and Self-Esteem in Depressive Patient / 신경정신의학

OBJECTIVES: The aim of this study was to examine the relationship between the Object Relations, Parenting Behaviors, and Self-esteem with Depression. METHODS: This study included 60 Depression patients and 90 healthy individuals. Parent Behavior Inventory (PBI), Bell Object Relation Inventory (BORI), Self-Esteem Scale (SES) and Beck Depression Inventory (BDI) were used for measuring parenting behaviors, object relations, self-esteem and severity of depression in orderly. RESULTS: Depression was negatively associated with self-esteem, and positively associated with four subscale of Object relation. Also, depression was positively associated with maternal intrusiveness, parental negligence and negatively associated with maternal affection. The most potent variable to explain depression was self-esteem, and the second was insecure attachment. Maternal affection was the most explainable variable of self-esteem, and the most potent variable of insecure attachment was maternal intrusiveness. Correlation analysis with insecure attachment and self-esteem as control variable individually, there was weak correlation among variables. CONCLUSION: This study shows object relation, parent behavior, and self-esteem are related with depressive symptoms. Object relation (especially, insecure attachment) and self-esteem is more important and proximal cause in depression than parental behavior. Result of the present study indicated that inadequate parental behavior in childhood foster insecure object relation and low self-esteem, then they contribute to depression through their interaction.