• Tuberculosis and Respiratory Diseases
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• v.85 no.1
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• pp.18-24
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• 2022

Background: Neutrophilic asthma (NeuA) is usually resistant to corticosteroids. Tiotropium bromide (TIO) is a bronchodilator that is used as an add-on therapy to inhaled corticosteroid and long-acting β2 agonist in asthma treatment. However, the role of TIO in NeuA is not fully known. Thus, the aim of this study was to evaluate the effect of TIO on NeuA compared to that of corticosteroids. Methods: C57BL/6 female mice were sensitized with ovalbumin and lipopolysaccharide to induce neutrophilic inflammation. Dexamethasone (DEX) was administered on days 14, 17, 20, and 23. TIO was inhaled on days 21, 21, and 23. On day 24, mice were sacrificed. Airway hyper-responsiveness, levels of cytokines in bronchoalveolar lavage (BAL) and lung homogenates, and lung tissue histopathology were compared between the two groups. Results: Neutrophil counts, T helper 2 cells (T_H2)/T_H17 cytokines, and pro-inflammatory cytokine in BAL fluids were elevated in the NeuA group. TIO group showed lower total cells, neutrophil counts, and eosinophil counts in BAL fluids than the DEX group (p<0.001, p<0.05, and p<0.001, respectively). Airway resistance was attenuated in the TIO group but elevated in the NeuA group (p<0.001). Total protein, interleukin (IL)-5, and IL-17A levels in BAL fluids were lower in the TIO group than in the NeuA group (all p<0.05). Conclusion: TIO showed more potent effects than DEX in improving airway inflammation and attenuating airway resistance in NeuA.

• Tuberculosis and Respiratory Diseases
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• v.85 no.1
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• pp.89-95
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• 2022

Background: With the introduction of Xpert MTB/RIF assay (Xpert), its incorporation into tuberculosis (TB) diagnostic algorithm has become an important issue. The aim of this study was to evaluate the performance of the Xpert assay in comparison with a commercial polymerase chain reaction (PCR) assay. Methods: Medical records of patients having results of both Xpert and AdvanSure TB/NTM real-time PCR (AdvanSure) assays using the same bronchial washing specimens were retrospectively reviewed. Results: Of the 1,297 patients included in this study, 205 (15.8%) were diagnosed with pulmonary TB. Using mycobacterial culture as the reference method, sensitivity of the Xpert assay using smear-positive specimens was 97.5%, which was comparable to that of the AdvanSure assay (96.3%, p=0.193). However, the sensitivity of the Xpert assay using smear-negative specimens was 70.6%, which was significantly higher than that of the AdvanSure assay (52.9%, p=0.018). Usng phenotypic drug susceptibility testing as the reference method, sensitivity and specificity for detecting rifampicin resistance were 100% and 99.1%, respectively. Moreover, a median turnaround time of the Xpert assay was 1 day, which was significantly shorter than 3 days of the AdvanSure assay (p<0.001). Conclusion: In comparison with the AdvanSure assay, the Xpert assay had a higher sensitivity using smear-negative specimens, a shorter turnaround time, and could reliably predict rifampin resistance. Therefore, the Xpert assay might be preferentially recommended over TB-PCR in Korean TB diagnostic algorithm.

• Tuberculosis and Respiratory Diseases
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• v.85 no.3
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• pp.264-272
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• 2022

Background: The current conventional drug susceptibility test (DST) for Mycobacterium tuberculosis (Mtb) takes several weeks of incubation to obtain results. As a rapid method, molecular DST requires only a few days to get the results but does not fully cover the phenotypic resistance. A new rapid method based on the ability of viable Mtb bacilli to hydrolyze fluorescein diacetate to free fluorescein with detection of fluorescent mycobacteria by flow cytometric analysis, was recently developed. Methods: To evaluate this cytometric method, we tested 39 clinical isolates which were susceptible or resistant to isoniazid (INH) or rifampin (RIF), or ethambutol (EMB) by phenotypic or molecular DST methods and compared the results. Results: The susceptibility was determined by measuring the viability rate of Mtb and all the isolates which were tested with INH, RIF, and EMB showed susceptibility results concordant with those by the phenotypic solid and liquid media methods. The isolates having no mutations in the molecular DST but resistance in the conventional phenotypic DST were also resistant in this cytometric method. These results suggest that the flow cytometric DST method is faster than conventional agar phenotypic DST and may complement the results of molecular DST. Conclusion: In conclusion, the cytometric method could provide quick and more accurate information that would help clinicians to choose more effective drugs.

• Tuberculosis and Respiratory Diseases
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• v.85 no.3
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• pp.256-263
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• 2022

Background: Mycobacterium tuberculosis (Mtb) is resistant to the β-lactam antibiotics due to a non-classical transpeptidase in the cell wall with β-lactamase activity. A recent study showed that meropenem combined with clavulanate, a β-lactamase inhibitor, was effective in multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB). However, in Korea, clavulanate can only be used as drugs containing amoxicillin. In this study, we investigated the susceptibility and genetic mutations of drug-resistant Mtb isolates to amoxicillin-clavulanate and meropenem-clavulanate to improve the diagnosis and treatment of drug-resistant TB patients. Methods: The minimum inhibitory concentration (MIC) of amoxicillin-clavulanate and meropenem-clavulanate was examined by resazurin microtiter assay. We used 82 MDR and 40 XDR strains isolated in Korea and two reference laboratory strains. Mutations of drug targets blaC, blaI, ldtA, ldtB, dacB2, and crfA were analyzed by polymerase chain reaction and DNA sequencing. Results: The MIC₉₀ values of amoxicillin/clavulanate and meropenem/clavulanate in drug-resistant Mtb isolates were 64/2.5 and 16/2.5 mg/L, respectively. Gene mutations related to amoxicillin/clavulanate and meropenem/clavulanate resistance could not be identified, but T448G mutation was found in the blaC gene related to β-lactam antibiotics' high susceptibility. Conclusion: Our results provide clinical consideration of β-lactams in treating drug-resistant TB and potential molecular markers of amoxicillin-clavulanate and meropenem-clavulanate susceptibility.

• Tuberculosis and Respiratory Diseases
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• v.86 no.1
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• pp.47-56
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• 2023

Background: There is a global increase in isolation of nontuberculous mycobacteria (NTM). The aim of the study was to analyze longitudinal trends of NTM identification and pattern of antimicrobial susceptibility testing. Methods: NTM recovery rates, distribution of NTM species identification, and antimicrobial susceptibility pattern of NTM at Pusan National University Yangsan Hospital between January 2016 and December 2020 were retrospectively analyzed. Results: A total of 52,456 specimens from 21,264 patients were submitted for mycobacterial culture, of which 2,521 from 1,410 patients were NTM positive over five years (January 2016 to December 2020). NTM isolation showed an increasing trend from 2016 to 2020 (p<0.001, test for trend) mainly caused by Mycobacterium avium complex. The vast majority of M. avium complex were susceptible to key agents clarithromycin and amikacin. For Mycobacterium kansasii, resistance to rifampin and clarithromycin is rare. Amikacin was the most effective drug against Mycobacterium abscessus subspecies abscessus and Mycobacterium subspecies massiliense. Most of M. subspecies massiliense were susceptible to clarithromycin, while the majority of M. abscessus subspecies abscessus were resistant to clarithromycin (p<0.001). Conclusion: There was an increasing trend of NTM isolation in our hospital. Resistance to key drugs was uncommon for most NTM species except for M. abscessus subspecies abscessus against clarithromycin.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.3
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• pp.175-181
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• 2002

Intermaxillary fixation and occusal splint are routine procedure for maxillofacial fracture and orthognathic surgery. When these methods could obstruct oral airway the patients who kept intermaxillary fixation and occusal splint in their mouth, are very difficult to breath after surgery. Nasal bleeding and pharyngeal edema due to nasotracheal intubation, residual effect of muscle relaxants, and anesthetic agent could be contributing factor of airway obstruction. In this study, pulmonary function test was evaluated before and after intermaxillary fixation, and intermaxillary fixation with occusal splint in 22 volunteers. The results were as follows 1. FVC, %FVC, $FEV_1$, $FEV_1%$, PEF, $PEF_{50}$, MVV without intermaxillary fixtion were 4.45L, 88%, 4.03L, 90.9%, 10.26L/s, 5.53L/s, and 136.14L/min, and with intermaxillary fixation were 3.51L, 68.67%, 3.06L, 69.39L, 6.52L/s, 3.94L/s, and 69.39L/min. The results with intermaxillary fixation and occusal splint were 2.15L, 42.41%, 1.71L, 38.81%, 2.83L/s, 1.74L/s, and 37.14L/min. 2. Compared with before and after intermaxillary fixation, all values of pulmonary function test were decreased and after intermaxillary fixation and intermaixillary fixation with occulasal splint, the results were decreased. 3. MVV and PEF were decreased significantly with interaxillary fixtion and occusal splint, and FVC was less decreased. It meant that intermaxillary fixation and occluasal splint induced reduction of respiratory flow significantly, but less reduction of respiratory volume. 4. Intermaxillary fixation and occulsal splint induced increase of airway resistance, decrease of expiratory volume and air flow. So severe respiratory difficulty could be seen to all volunteers who kept intermaxillary fixtion and occusal splint. 5. In classification of respiratory difficulty, intermaxillary fixation with occulsal splint induced complex respiratory difficulty more than intermaxillary fixation only did. From the above results, doctors who care patients kept intermaxillary fixation and occusal splint should be aware of respiratory depression caused by these treatment.

• Tuberculosis and Respiratory Diseases
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• v.80 no.2
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• pp.159-168
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• 2017

Background: Streptomycin (SM) is recommended by the World Health Organization (WHO) as a part of standard regimens for retreating multidrug-resistant tuberculosis (MDR-TB) cases. The incidence of MDR-TB in retreatment cases was 19% in Thailand. To date, information on SM resistance (SMR) gene mutations correlated to the SMR of Mycobacterium tuberculosis Thai isolates is limited. In this study, the mutations in rpsL, rrs, gidB, and whiB7 were investigated and their association to SMR and the lineage of M. tuberculosis were explored. Methods: The lineages of 287 M. tuberculosis collected from 2007 to 2011 were identified by spoligotyping. Drug susceptibility profiles were evaluated by the absolute concentration method. Mutations in SMR genes of 46 SM-resistant and 55 SM-susceptible isolates were examined by DNA sequencing. Results: Three rpsL (Lys43Arg, Lys88Arg, and Lys88Thr) and two gidB (Trp45Ter and Gly69Asp) mutations were present exclusively in the SM resistant M. tuberculosis. Lys43Arg rpsL was the most predominant SMR mutations (69.6%) and prevailed among Beijing isolates (p<0.001). No SMR-related mutation in was found rrs. The combination of rpsL and gidB mutations provided 76.1% sensitivity for detecting SMR in M. tuberculosis Thai isolates. whiB7 was not responsible for SMR in SM resistant isolates lacking rpsL and rrs mutations. The significance of the three gidB mutations, 276A>C, 615A>G, and 330G>T, as lineage signatures for Beijing and EAI were underscored. This study identified 423G>A gidB as a novel sub-lineage marker for EAI6-BGD1. Conclusion: Our study suggested that the majority of SMR in M. tuberculosis Thai isolates were responsible by rpsL and gidB polymorphisms constantly providing the novel lineage specific makers.

• Tuberculosis and Respiratory Diseases
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• v.59 no.3
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• pp.266-271
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• 2005

Background : Ethambutol(EMB) is one of the first-line drugs included in short-course anti-tuberculosis therapy. The point mutations in embB gene have been speculated to be associated EMB resistance. However, detection of embB mutations at these positions have been observed in both EMB-susceptible isolates; thus, it remains controversial whether these mutations are associated with EMB resistance Methods : The 36 M. tuberculosis isolates were selected from clinical isolates which tested susceptible to EMB and resistant to at least one drug. DNA extracted from the isolates was analyzed by amplifying embB gene. The PCR products were purified and directly sequenced. We reviewed the history of past drug susceptibility test results. Results : Out of 36 EMB-susceptible strains, 3 strains (8.3%) had a mutation in codon 306 or 406 of the embB gene. These three strains had at least isoniazid resistance. They grew at 1.0 mcg/ml of EMB in Lowenstein-Jensen media. The patients of the strains were continuously smear-positive for over 3 years despite taking TB therapy. One strain had been EMB-resistant in past drug susceptibility tests. Conclusion : EMB-susceptible strains containing embB mutation may be caused by decreased viability in vitro test not by itself.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.863-870
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• 2005

One hundred and twenty three strains of Mycoplasma pneumoniae were isolated from patients with respiratory diseases from February 2002 to April 2005 in Busan, Korea. The MICs of tetracycline and erythromycin up to $90\%$ of the 123 M. pneumoniae isolates tested were $0.5\~1.0$, and $0.5\~512{\mu}/ml$, respectively. Plasmid DNA was not isolated from all of the M. pneumoniae isolates. Out of 323 strains of M. pneumoniae, 57 ($46.3\%$) stains contain tetM gene on their chromosomal DNA, and 60 ($48.8\%$) strains were mutated in domain V of 23S rRNA for erythromycin resistance. Out of 63 strains of M. pneumoniae which were not mutated in domain V of 235 rRNA for erythromycin resistance, 36 ($57.1\%$) strains contained tetM gene, and out of 60 strains of M. pneumoniae which were mutated in domain V of 23S rRNA for erythromycin resistance, 21 ($35.0\%$) strains contained tetM gene. These results suggest that the isolation rate of erythromycin and tetracycline resistant M. pneumoniae is higher than those of other countries, and erythromycin and tetracycline are not first choice drug for M. pneumoniae infection in Korea, and it need confirm by a nationwide surveilance of antimicrobial resistance.

• Tuberculosis and Respiratory Diseases
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• v.62 no.6
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• pp.506-515
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• 2007

Background: Nosocomial pneumonia in an intensive care unit (ICU) is associated with a high mortality rate. Diagnosing a respiratory tract infection in critically ill patients is still difficult but detailed information for the pathogens is needed to establish an adequate antimicrobial treatment. This study examined the causative organisms and their antimicrobial resistance using bronchoalveolar lavage (BAL) from patients suspected of having pneumonia in the ICU. Methods: From January 2004 to June 2006, ICU patients with diffuse lung infiltration were prospectively enrolled. The BAL was used to diagnose the respiratory infection, with 104 > or = organisms considered a positive result. The most common organisms and their antimicrobial resistances were analyzed from the quantitative BAL cultures in the burn ICU and non-burn ICU. Results: A total 72 patients were included, 35 (M 29, F 6) in the burn ICU and 37 (M 26, F 11) in the non-burn ICU. 27 patients (77.1%) in the burn ICU and 22 patients (59.5%) in the non-burn ICU met the criteria for a positive BAL culture. The major pathogens were Staphylococcus aureus, Acinetobacter species and Pseudomonas aeruginosa. All strains (100%) of Staphylococcus aureus isolated from BAL (9 cases) were methicillin-resistant (MRSA) in the burn ICU, but 5 strains (71.4%, 7 cases) were MRSA in the non-burn ICU. Regarding Pseudomonas aeruginosa, the rate of resistance to amikacin, ciprofloxacin, cefepime, imipenem, ceftazidime, piperacillin/tazobactam in the burn and non-burn ICU ranged from 45.5% to 90% and 25% to 50%, respectively. In addition, the rate of resistance of Acinetobacter species to the above drugs in the burn and non-burn ICU ranged from 81.8% to 100% and 62.5% to 100%, respectively. Conclusions: These results are expected to provide useful guidelines for choosing the effective empirical antimicrobial therapy in patients with lung infiltrations in the burn and non-burn ICU.