• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.590-596
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• 2006

Clavulanic acid (CA) produced by Streptomyces clavuligerus is degraded during the bacterial cultivation. The degradation was examined in three different aspects, including physical, chemical, and enzymatic effects, in order to understand the degradation during the cultivation. The result showed that CA was unstable in the production medium containing ammonium salts and amino acids, owing to ammonium ions and amine groups. In addition, the degradation was not only due to instability of CA by metabolites and proteins, but also enzymes from S. clavuligerus such as $\beta-lactamase$ and penicillin-binding proteins. However, the degradation caused by these enzymes was not highly significant compared with the degradation during the cultivation, owing to irreversible reactions between CA and enzymes.

• Journal of Oral Medicine and Pain
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• v.46 no.3
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• pp.88-92
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• 2021

Acute osteomyelitis caused by Klebsiella pneumoniae is rare in the oral and maxillofacial region. Klebsiella pneumoniae is a Gram-negative bacillus and the normal flora of the human body, but it can cause pneumonia, urinary tract infection, meningitis, and osteomyelitis in patient with compromised immune systems. These infections are mainly caused by nosocomial infection. Microbacterial osteomyelitis was developed by clinical cause such as tooth extraction, fracture, and surgical history, which requires long-term antibiotic administration and surgical treatment. This report describes that a 56-year-old male patient with acute osteomyelitis caused by Klebsiella pneumoniae infection after implant placement was treated with intravenous administration of ertapenem without open surgery treatment. Through this case, we report that antibiotic susceptibility test is essential for the treatment of acute osteomyelitis caused by a bacterial infection resistant to empirical antibiotics, and early administration of appropriate antibiotics can reduce the possibility of extensive bone destruction or additional open surgery.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.278-288
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• 2019

In the present investigation, we attempted to design a protocol to develop a hybrid protein with better bioremediation capacity. Using in silico approaches, a Hybrid Open Reading Frame (Hybrid ORF) is developed targeting the genes of microorganisms known for degradation of organophosphates. Out of 21 genes identified through BLAST search, 8 structurally similar genes (opdA, opd, opaA, pte RO, pdeA, parC, mpd and phnE) involved in biodegradation were screened. Gene conservational analysis categorizes these organophosphates degrading 8 genes into 4 super families i.e., Metallo-dependent hydrolases, Lactamase B, MPP and TM_PBP2 superfamily. Hybrid protein structure was modeled using multi-template homology modeling (3S07_A; 99%, 1P9E_A; 98%, 2ZO9_B; 33%, 2DXL_A; 33%) by $Schr{\ddot{o}}dinger$ software suit version 10.4.018. Structural verification of protein models was done using Ramachandran plot, it was showing 96.0% residue in the favored region, which was verified using RAMPAGE. The phosphotriesterase protein was showing the highest structural similarity with hybrid protein having raw score 984. The 5 binding sites of hybrid protein were identified through binding site prediction. The docking study shows that hybrid protein potentially interacts with 10 different organophosphates. The study results indicate that the hybrid protein designed has the capability of degrading a wide range of organophosphate compounds.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.465-472
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• 2019

Several reports describe antimicrobial-resistance transfer among children and the community in outbreak situations, but transfer between a child and a caregiver has not been examined in child care facilities under normal circumstances. We investigated the transfer of antimicrobial-resistance genes, resistant bacteria, or both among healthy children and teachers. From 2007 to 2009, 104 Escherichia coli isolates were obtained from four teachers and 38 children in a child care center. Twenty-six cephem-resistant isolates were obtained from children in 2007 and 2008. In 2009, cephem-resistant isolates were detected in children as well as a teacher. Nalidixic acid-resistant isolates from the same teacher for 3 years showed low similarity (<50%) to each other. However, an isolate from a teacher in 2007 and another from a child in 2008 showed high similarity (87%). Pulsed-field gel electrophoresis revealed 100% similarity for four isolates in 2007 and one isolate in 2008, and also similarity among seven isolates carrying the virulence gene (CNF1). This study yielded the following findings: (1) a gene for extended-spectrum ${\beta}$-lactamase was transferred from a child to other children and a teacher; (2) a nalidixic acid-resistant isolate was transferred from a teacher to a child; and (3) a virulent bacterium was transferred between children.

• Tuberculosis and Respiratory Diseases
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• v.74 no.2
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• pp.63-69
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• 2013

Background: Aiming to improve outcome of lung transplantation (LTx) patients, we reviewed risk factors and treatment practices for the LTx recipients who experienced respiratory infection in the late post-LTx period (>1 month after LTx). Methods: We analyzed the clinical data of 48 recipients and donors from 61 LTx, who experienced late respiratory infections. Late respiratory infections were classified according to the etiology, time of occurrence, and frequency of donor-to-host transmission or colonization of the recipient prior to transplantation. Results: During the period of observation, 42 episodes of respiratory infections occurred. The organisms most frequently involved were gram (-) bacteria: Acinetobacter baumannii (n=13, 31.0%), Pseudomonas aeruginosa (n=7, 16.7%), and Klebsiella pneumoniae (n=4, 10.0%). Among the 42 episodes recorded, 14 occurred in the late post-LTx period. These were bacterial (n=6, 42.9%), fungal (n=2, 14.3%), viral (n=4, 28.5%), and mycobacterial (n=2, 14.3%) infections. Of 6 bacterial infections, 2 were from multidrug-resistant (MDR) A. baumannii and one from each of MDR P. aeruginosa, extended spectrum ${\beta}$-lactamase (+) K. pneumoniae, methicillin-resistant Staphylococcus aureus and Streptococcus pneumoniae. Infection-related death occurred in 6 of the 14 episodes (43%). Conclusion: Although the frequency of respiratory infection decreased sharply in the late post-LTx period, respiratory infection was still a major cause of mortality. Gram (-) MDR bacteria were the agents most commonly identified in these infections.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.349-354
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• 2016

The emergence and dissemination of extended-spectrum ${\beta}$-lactamse (ESBL) producing Klebsiella pneumoniae isolates make it more difficult to treatment of bacterial infections. In our study, we detected ESBL genes and investigated antimicrobial susceptibility of K. pneumoniae isolates in Chungcheong province. In addition, clonality among the isolates was analyzed by repetitive element sequence (REP)-PCR. Twenty-one of 102 K. pneumoniae isolates produced CTX-M-14 and/or CTX-M-15 and showed high level (over 70%) resistance to third cephalosporins. CTX-M type ESBL producing K. pneumoniae strains isolated in our study showed diverse clonality and some of the isolates have been disseminated in the community. Enhancing infection control will be needed to prevent dissemination of the K. pneumoniae isolates. In addition, for more effective control of resistant bacteria it is considered necessary to monitor the database constructed through convergence of biological investigation and statistical analysis of antimicrobial resistance genes.

• Biomedical Science Letters
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• v.21 no.2
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• pp.84-91
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• 2015

To provide guidelines for the empirical treatment of urinary tract infections, we observed annual changes in the occurrence frequency and antimicrobial susceptibility of urinary isolates in a university hospital in the Chungbuk province, South Korea, over a period of 10 years (2004~2013). Escherichia coli (38.2%), Enterococcus faecalis (11.7%), Klebsiella pneumoniae (7.3%), Pseudomonas aeruginosa (4.3%), E. faecium (4.3%), and Staphylococcus aureus (4.1%) were commonly isolated urinary pathogens. The prevalence of E. coli, E. faecium and Streptococcus agalactiae were significantly higher in females (P < 0.001), whereas E. faecalis, P. aeruginosa and S. aureus were significantly more common in male patients (P < 0.001). E. coli mostly frequently showed resistance to ampicillin (67.94%), followed by trimethoprim/sulfamethoxazole (36.06%) and ciprofloxacin (26.84%). Over the studied time period, resistance rates of E. coli to ciprofloxacin significantly increased (20.44% to 33.55%). Moreover, extended-spectrum $\beta$-lactamase (ESBL) producing isolates also significantly increased in E. coli (4.2% to 18.3%) and K. pneumoniae (9.6% to 26.9%). In addition, the proportion of vancomycin-resistant Enterococcus facium (VRE) also increased (15.7% to 25.0%). In conclusion, over the last 10 years, the proportions of ciprofloxacin resistant E. coli and multidrug-resistant bacteria, such as ESBL and VRE have significantly increased. This trend must be strictly controlled and demonstrates the need for more updated guidelines for the treatment of urinary tract infections.

• Childhood Kidney Diseases
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• v.21 no.2
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• pp.121-127
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• 2017

Purpose: The aim of this study was to determine the prevalence of antibiotic susceptibility and resistance of Escherichia coli in urinary tract infections (UTIs) in children. Methods: We retrospectively reviewed the clinical records of 212 inpatients aged 18 years or younger with UTIs treated at the Pediatric Department of Dongguk University Gyeongju Hospital between January 2008 and December 2016. For comparison, patients were divided into three groups according to age as follows: group 1, ${\leq}1$ month; group 2, >1 month to ${\leq}12$ months; and group 3, ${\geq}13$ months. The antibiotic resistance rates from January 2008 to December 2012 (study period 1) and from January 2013 to December 2016 (study period 2) were analyzed statistically by group. Results: As the patient age increased, the antibiotic resistance rate to ampicillin (P=0.013), levofloxacin (P=0.050), piperacillin/tazobactam (TZP) (P<0.001), and trimethoprim/sulfamethoxazole (P=0.002) increased. The frequency of extended spectrum beta-lactamase producing E. coli showed a significant difference from 5 cases (4.6%) in study period 1 and 16 cases (15.8%) in study period 2 (P=0.007). The antibiotic resistance rate of E. coli was compared between the two time periods and we found that the antibiotic resistance rate to cefotaxime was significantly increased from 5.4% to 16.8% (P=0.008) and that to TZP was significantly decreased from 40.5% to 7.9% (P<0.001). Conclusion: Over the past 9 years, the resistance rate to cefotaxime has increased but the resistance rate to TZP has decreased. Thus, it is important to continue to investigate the antibiotic resistance rates of bacteria in the community.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1643-1649
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• 2016

The aims of this study were to characterize the molecular epidemiological profiles of CTX-M-producing uropathogenic Escherichia coli isolates from a tertiary hospital in Daejeon, Korea, and to investigate the genetic diversity and compare the prevalence of sequence types (STs) in different areas. Extended spectrum β-lactamase-producing E. coli strains isolated from urine were analyzed for CTX-M, integrons, and insertion sequence common regions (ISCRs) by PCR and sequencing. Multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), phylogenetic analysis, and rep-PCR were also used for molecular typing of the isolates. Of 80 CTX-M producers, 31 and 46 expressed CTX-M-15 and CTX-M-14, respectively. MLST analysis indicated that the most prevalent ST was ST131 (n = 34, 42.5%), followed by ST38 (n = 22, 27.5%), ST405 (n = 8, 10.0%), and ST69 (n = 6, 7.5%). Most CTX-M producers harbored class 1 integrons. ST131 strains belonged to phylogenetic group B2 and showed identical rep-PCR patterns, whereas ST69, ST38, and ST405 strains belonged to phylogenetic group D; the ST38 and ST405 strains displayed the same rep-PCR pattern, respectively. ST131 and ST38 isolates showed 21 and 19 distinct types, respectively, by PFGE. In Daejeon, D-ST38 CTX-M-14 producers were relatively more prevalent than in other countries and Korean cities. Our results indicate that CTX-M-producing E. coli isolates belonged mostly to ST131 or ST38 and were more related to hospital-onset than to community-onset infections and that the bla_CTX-M gene may vary according to the ST.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.146-152
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• 2010

Streptomyces clavuligerus NRRL3585 produces a clinically important $\beta$-lactamase inhibitor, clavulanic acid (CA). In order to increase the production of CA, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene (gap) was deleted in S. clavuligerus NRRL3585 to overcome the limited glyceraldehyde-3-phosphate pool; the replicative and integrative expressions of ccaR (specific regulator of the CA biosynthetic operon) and claR (Lys-type transcriptional activator) genes were transformed together into a deletion mutant to improve clavulanic acid production. We constructed two recombinant plasmids to enhance the production of CA in the gap1 deletion mutant of S. clavuligerus NRRL3585: pHN11 was constructed for overexpression of ccaR-claR, whereas pHN12 was constructed for their chromosomal integration. Both pHN11 and pHN12 transformants enhanced the production of CA by 2.59-fold and 5.85-fold, respectively, compared with the gap1 deletion mutant. For further enhancement of CA, we fed the pHN11 and pHN12 transformants ornithine and glycerol. Compared with the gap1 deletion mutant, ornithine increased CA production by 3.24- and 6.51-fold in the pHN11 and pHN12 transformants, respectively, glycerol increased CA by 2.96- and 6.21-fold, respectively, and ornithine and glycerol together increased CA by 3.72- and 7.02-fold, respectively.