• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1178-1184
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• 2018

The spread of antibiotic-resistant Enterobacteriaceae in the community is one of the main challenges for antibiotic treatment of community-onset infections. We evaluated the microbiological and molecular characteristics of stool samples from adults with comprehensive health examinations. Of 109 fecal samples, bacterial growth was observed in 86 samples and 61 gram-negative bacterial isolates were identified, of which 45 were Escherichia coli isolates (73.8%). Two isolates of Raoultella showed imipenem resistance, and both E. coli and Citrobacter freundii showed intermediate resistance to imipenem. Colistin resistance was identified in isolates of Klebsiella variicola and Salmonella subterranean, but no isolates carried mcr-1. As for E. coli genotypes, 35 sequence types were identified. $bla_{TEM-1}$, $bla_{TEM-30}$, and $bla_{CTX-M}$ were identified in 15, 1, and 4 E. coli isolates, respectively. In addition, all four Klebsiella pneumoniae isolates carried $bla_{SHV}$. Many genotypes that have been identified in isolates causing human infections were found in isolates in this study. There is a need to control the rise and spread of antibiotic-resistant pathogens by fecal carriage.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1711-1715
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• 2017

In this study, we characterized the $bla_{NDM-5}$-bearing plasmid in a Klebsiella pneumoniae isolate that had lost the plasmid during serial passage. We determined the complete sequences of the plasmid pCC1410-2, which was extracted from a K. pneumoniae ST709 isolate collected at a Korean hospital from which two NDM-5-producing K. pneumoniae isolates were subsequently isolated. As a result, the pCC1410-2 plasmid had a backbone structure that was similar to those of two plasmids previously reported from the same hospital, but lacked some antibiotic resistance genes ($bla_{TEM-1}$, rmtB, mphR(A), mrx(A), and mph(A)). A 9-bp repeating unit encoding three amino acids (Gln-Gln-Pro) was inserted in TraD in pCC1410-2. Thus, the pCC1410-2 plasmid might be transferred from the previously identified carbapenem-resistant K. pneumoniae, but some delections and inversions might have occurred during the process. We compared the transfer frequency and stability of the plasmids. The relative frequency of conjugative transfer and stability in the host were significantly lower in pCC1410-2 than in previously reported $bla_{NDM-5}$-bearing plasmids in Korea. A low transfer frequency and instability in the host may cause underestimation of carbapenemase-producing Enterobacteriaceae in the clinical setting and in surveillance studies.

• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.230-235
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• 2020

The global evolution of antibiotic resistance has threatened the efficacy of available treatment options with ravaging impacts observed in developing countries. As a result, investigations into the prevalence of antibiotic resistance and the role of plasmids are crucial. In this study, we investigated the presence and distribution of bla_TEM and gyrA genes, plasmid profiles, and the antimicrobial susceptibility pattern of Salmonella strains isolated from raw meat and stool sources across Niger State, Nigeria. Ninety-eight samples, comprising 72 raw meat and 26 stool samples, were screened for Salmonella spp. The antimicrobial susceptibility of Salmonella isolates to 10 commonly used antimicrobial agents was determined using the KirbyBauer disc diffusion method. Isolates were further analyzed for plasmids, in addition to PCR amplification of beta-lactamase (bla_TEM) and gyrA genes. A total of 31 Salmonella spp. were isolated, with 22 from raw meat (70.97%) and 9 from stool (29.03%). Salmonella spp. with multiple resistance patterns to ceftazidime, cefuroxime, ceftriaxone, erythromycin, ampicillin, cloxacillin, and gentamicin were detected. Ofloxacin and ciprofloxacin were found to be the most effective among the antibiotics tested, with 67.7% and 93.5% susceptible isolates, respectively. Nine (29.03%) isolates harbored plasmids with molecular sizes ranging between 6557 bp and 23137 bp. PCR amplification of gyrA was detected in 1 (3.23%) of the 31 isolates while 28 isolates (90.32%) were positive for bla_TEM. This study shows the incidence of antibiotic resistance in Salmonella isolates and the possible role of plasmids; it also highlights the prevalence of ampicillin resistance in this local population.

• Archives of Pharmacal Research
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• v.24 no.6
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• pp.590-596
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• 2001

A new extended-spectrum ${\beta}-lactamase$ with an isoelectric point (pl) of 6.2 was detected in Klebsiella pneumoniae Fl 61 that was isolated from a patient with infection. This strain was highly resistant to the third or fourth generation cephalosporins such as cceftazidime ceftriaxone, cefoperzaone, and cefpirome. Analysis of this strain by the double disk diffusion test showed synergies between amoxicillin-clavulanate (AMX-CA) and cefotaxime, and AMX-CA and aztreonam, which suggested that this strain produced a extended-spectrum ${\beta}-lactamase$ (ESBL). Cenetic analysis revealed that the resistance was due to the presence of a 9.4-kb plasmic, designated as pkpl 61, encoding for new ${\beta}-lactamase$ gene (bla). Sequence analysis showed that a new bla gene of pkpl 61 differed from $bla_{TEM-1}$ by three mutations leading to the following amino acid substitutions: $Val_{84}{\rightarrow}lie,{\;}Ala_{184}{\rightarrow}Val,{\;}and{\;}Gly_{238}{\rightarrow}Ser$. These mutations have not been reported previously in the TIM type ${\beta}-lactamases$ produced by clinical strains. The novel ${\beta}-lactamase$ was overexpressed in E. coli and purified by ion exchange chromatography on Q-Sepharose and CM-Sepharose, and then further purified by gel filtration on Sehadex G-200. The catalytic activity of th8 purified ${\beta}-lactamase$ was confirmed by the nitrocefin disk.

• Journal of Microbiology and Biotechnology
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• v.31 no.12
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• pp.1672-1683
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• 2021

Vibrio parahaemolyticus is recognized as one of the most important foodborne pathogens responsible for gastroenteritis in humans. The bla_CARB-17 gene is an intrinsic β-lactamase gene and a novel species-specific genetic marker of V. parahaemolyticus. In this study, a loop-mediated isothermal amplification (LAMP) assay combined with a lateral flow dipstick (LFD) was developed targeting this bla_CARB-17 gene. The specificity of LAMP-LFD was ascertained by detecting V. parahaemolyticus ATCC 17802 and seven other non-V. parahaemolyticus strains. Finally, the practicability of LAMP-LFD was confirmed by detection with V. parahaemolyticus-contaminated samples and natural food samples. The results showed that the optimized reaction parameters of LAMP are as follows: 2.4 mmol/l Mg²⁺, 0.96 mmol/l dNTPs, 4.8 U Bst DNA polymerase, and an 8:1 ratio of inner primer to outer primer, at 63℃ for 40 min. The optimized reaction time of the LFD assay is 60 min. Cross-reactivity analysis with the seven non-V. parahaemolyticus strains showed that LAMP-LFD was exclusively specific for V. parahaemolyticus. The detection limit of LAMP-LFD for V. parahaemolyticus genomic DNA was 2.1 × 10^-4 ng/μl, corresponding to 630 fg/reaction and displaying a sensitivity that is 100-fold higher than that of conventional PCR. LAMP-LFD in a spiking study revealed a detection limit of approximately 6 CFU/ml, which was similar with conventional PCR. The developed LAMP-LFD specifically identified the 10 V. parahaemolyticus isolates from 30 seafood samples, suggesting that this LAMP-LFD may be a suitable diagnostic method for detecting V. parahaemolyticus in aquatic foods.

• Microbiology and Biotechnology Letters
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• v.51 no.3
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• pp.268-279
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• 2023

The pharmaceutical industry in Bangladesh produces a diverse range of antibiotics for human and animal use, however, waste disposal management is inadequate. This results in substantial quantities of antibiotics being discharged into water bodies, which provide suitable environment for the growth of antibiotic-resistant bacteria, capable of spreading resistance genes. This study intended for exploring the bacterial antibiotic resistance profile in adjoining aquatic environmental sources of pharmaceutical manufacturing facilities in Bangladesh. Seven surface water samples were collected from the vicinity of two pharmaceutical industries located in the Savar area and 51 Escherichia coli isolates were identified using both phenotypic and genotypic methods. Antibiotic susceptibility tests revealed the highest percentage of resistance against ampicillin, azithromycin, and nalidixic acid (100%) and the lowest resistance against meropenem (1.96%) out of sixteen different antibiotics tested. 100% of the study E. coli isolates were observed with Multidrug resistance phenotypes, with the Multiple Antibiotic Resistance (MAR) value ranging from 0.6-1.0. Furthermore, 69% of the isolates were Extended Spectrum Beta-Lactamases (ESBL) positive as per the Double Disk Diffusion Synergy Test (DDST). ESBL resistance genes bla_TEM, bla_CTX-M-13, bla_CTX-M-15, and bla_SHV were detected in 70.6% (n = 36), 60.8% (n = 32), 54.9% (n = 28), and 1.96% (n = 1) of the isolates, respectively, by Polymerase Chain Reaction (PCR). Additionally, 15.68% (n = 8) of the isolates were positive for E. coli specific virulence genes in PCR. These findings suggest that pharmaceutical wastewater, if not properly treated, could be a formidable source of antibiotic resistance spread in the surrounding aquatic environment. Therefore, continued surveillance for drug resistance among bacterial populations around drug manufacturing facilities in Bangladesh is necessary, along with proper waste disposal management.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.2
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• pp.170-178
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• 2011

The purpose of this study was to assess the prevalence of periodontopathic bacteria and resistance determinants from oral biofilm of children. Subgingival dental plaque was isolated from 87 healthy children, and PCR was performed to determine the presence of 5 periodontal pathogens including P. gingivalis, T. forsythia, T. denticola, F. nucleatum, A. actinomycetemcomitans, and nine resistance genes including tet(Q), tet(M), ermF, aacA-aphD, cfxA, $bla_{SHV}$, $bla_{TEM}$, vanA, mecA. 1. The prevalence of F. nucleatum, T. forsythia. and P. gingivalis was 95.4%, 55.2%, and 40.2%, respectively. In addition. the prevalence of A. actinomycetemc omitans was 5.7%, while T. denticola was 3.4%. 2. In analysis of antibiotic resistance determinants. cfxA, $bla_{TEM}$ and tet(M) were detected in all the samples tested. It was also found that the prevalence of tet(Q) showing tetracycline resistance. $bla_{SHV}$ associated with resistance to ${\beta}$-lactams, ermF exhibiting erythromycin resistance, and, vanA resulting vancomycin resistance was 88.5%, 29.9% 87.4%, and 48.5%, respectively. The aacA-aphD gene showing resistance to aminoglycosides and mecA gene harboring methicillin resistance exhibited the lowest prevalence with 9.2%. 3. In a correlation analysis between periodontopathic pathogens and antibiotic resistance determinants, it was found that there was a significant correlation between T. forsythia and $bla_{SHV}$. Also, P. gingivalis and vanA showed a correlation. Finally, tet(Q) and ermF showed a significant correlation (phi: 0.514) while mecA and vanA also showed a correlation(phi: 0.25).

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.217-224
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• 2016

Acinetobacter baumannii (A. baumannii) is prevalent in hospital environments and is an important opportunistic pathogen of nosocomial infection. It is known that this pathogen cause herd infection in hospitals, and the mortality rate is remarkably higher for patients infected with this pathogen and already have other underlying diseases. Herein, we investigated the antibiotic resistance rate and the type of resistance genes in 85 isolates of multi-drug resistant A. baumannii from the samples commissioned to laboratory medicine in two university hospitals-in hospital A and hospital B-located in Cheonan and Chungcheong provinces, respectively, in Korea. As a result, $bla_{OXA-23-like}$ and $bla_{OXA-51-like}$ were detected in 82 stains (96.5%). These 82 strains of $bla_{OXA-23-like}$ producing A. baumannii were confirmed with the ISAba1 gene found at the top of the $bla_{OXA-23-like}$ genes by PCR, inducing the resistance against carbapenemase. The armA, AME gene that induces the resistance against aminoglycoside was detected in 34 strains out of 38 strains from Hospital A (89.5%), and in 40 strains out of 47 strains from Hospital B (85.1%), while AMEs were found in 33 strains out of 38 strains from Hospital A (70.2%) and in 44 strains out of 47 strains in Hospital B (93.6%). Therefore, it was found that most multi-drug resistant A. baumannii from the Cheonan area expressed both acethyltransferase and adenyltransferase. This study investigated the multi-drug resistant A. baumannii isolated from Cheonan and Chungcheong provinces in Korea, and it is thought that the results of the study can be utilized as the basic information to cure multi-drug resistant A. baumannii infections and to prevent the spread of drug resistance.

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.765-770
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• 2014

This study aimed to characterize CTX-M producers of urinary E. coli and K. pneumoniae isolates and to determine the prevalence of plasmid-mediated antimicrobial resistance genes among them. Minimum inhibitory concentrations (MICs) were determined, and PCR and sequencing were performed. Among the 42 (82.3%) E. coli and 24 (77.4%) K. pneumoniae isolates containing $bla_{CTX-M}$, $bla_{CTX-M-14}$ and $bla_{CTX-M-15}$ were detected in 23 and 19 E. coli isolates, respectively, and in 7 and 17 K. pneumoniae isolates, respectively. CTX-M producers of urinary E. coli and K. pneumoniae were resistant to multiple antibiotics and contained other antimicrobial resistance genes. CTX-M-15 producers contained more antimicrobial resistance genes than did CTX-M-14 producers.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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• pp.173-178
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• 2006

The production of extended-spectrum ${\beta}$-lactamases ($ESBL_S$) is the main mechanism of bacterial resistance to third-generation cephalosporins and monobactams, whose prevalence varies depending on the different geographical areas. In the last years it has increased notably to the point of being considered a health problem of great importance. The characterization of the ESBLs producing Klebsiella penumoniae strains present in clinical isolates is time-consuming. I describe here the development of a new system, which consists of a multiplex PCR. I found 51 K. pneumoniae strains to be presumptive strains ESBLs producers by clinical and laboratory standards institute (CLSI) guidelines. The double disc synergy test showed 47 positive K. pneumoniae, which were K. pneumoniae isolates. All ESBLs producing K. pneumoniae strains were resistant to antibiotic amikacin, gentamicin and ciprofloxacin. By multiplex PCR analysis, $bla_{TEM}$ gene in 17 strains 44 $bla_{SHV}$ genes and $bla_{CTX}$ genes in 33 strains were identified. In this study, the multiplex polymerase chain reaction (PCR) assay was a good method to detect and differentiate ESBLs producing K. penumoniae strains in clinical isolates.