Kim GY, et al. J Periodontal Implant Sci. 2015 Dec;45(6):223-228. https://doi.org/10.5051/jpis.2015.45.6.223

Objective. This study is aimed at investigating the pattern of change occurring in respiratory pathogens before and after the outbreak of COVID‐19, a type of viral pneumonia for which a pandemic was declared (March 2020). The results were analyzed by gender and age to identify the association between personal hygiene and prevention of infection by respiratory pathogens. Methods. A retrospective analysis was performed on 39,814 sputum, bronchial aspirate, and transtracheal aspirate samples obtained from 15,398 patients visiting a university hospital, located in Chungcheongnam‐do, South Korea, between January 2018 and December 2021. From 4,454 patients whose samples were culture positive for bacteria, 6,389 strains were isolated and further cultured. Results. The mean age of the outpatients with respiratory pathogens was 66.2 years, and the comparison of the culture test results by gender showed that 64.9% (2,892/4,454) were male and 35.1% (1,562/4,454) were female. Compared to the pre‐COVID‐19 pandemic period, the number of outpatients with a request for respiratory microbial cultures after the onset of the pandemic was reduced by 20.7% and the number of outpatients with a positive culture result was reduced by 23.0%. The number of respiratory samples received was reduced by 6.7% after the pandemic, while the sample positive rate was reduced by 18.3%. Among the isolated microbial strains, there was a significant decrease of 43.1% for the Acinetobacter baumannii complex, 60.5% for Streptococcus pneumoniae, 67.2% for Haemophilus influenzae, and 78.1% for Moraxella catarrhalis when compared with pre‐COVID‐19 levels. The distribution of respiratory microbial strains by age group showed that the highest percentage of isolated strains was in patients in their 70s. Conclusions. The improvements in personal hygiene due to the COVID‐19 pandemic exerted a substantial influence on the pattern of change in other common respiratory microorganisms, which highlights the importance of personal hygiene management in the prevention of respiratory infections.

Background and Objectives: Developing effective treatment outcomes for multidrug-resistant Acinetobacter baumannii (MRAB) infections, with colistin and tigecycline the current frontline therapies, is challenging, because of the risk of renal toxicity and low blood concentrations of active ingredients when administered intravenously. This study aimed to identify the effect of combination therapy using conventional antimicrobial agents that are used for treating drug-resistant bacteria and the additional synergistic effect of four probiotic culture extracts isolated from the human body and Lactobacillus preparations. Materials and Methods: The antimicrobial combination and synergistic effect of adding Lactobacillus extract against 33 strains of A. baumannii isolated from pus, urine, and other specimens submitted to the Department of Laboratory Medicine of a university hospital, located in Gyeonggi-do, Korea, was investigated over a 3-year period between January 2017 and December 2019. Results: Antimicrobial susceptibility tests on bacteria isolated in clinical practice demonstrated that 26 strains (79%) were MRAB, while multi-locus sequence typing indicated that ST191 was the predominant type (45%; n = 15). Checkerboard test results demonstrated that combination therapy using meropenem and colistin had the highest synergistic effect (fractional inhibitory concentration index = 0.5), while the time–kill assay test using Lactobacillus spp. culture extract exhibited an inhibitory effect within 1 h and complete inhibition of MRAB within 3 h. Lactobacillus paracasei exhibited the fastest antimicrobial reactivity and longest sustained antimicrobial activity. Conclusion: These findings provide useful foundational data for an appropriate combination of colistin with other antimicrobial agents for treating MRAB infection in clinical settings, and the use of various probiotic culture extracts to reduce the required dosage, and therefore toxicity of colistin.

The aim of this study was to investigate the effects of administration of a mixture of Humulus japonicus (MH) on longitudinal bone growth in normal Sprague Dawley (SD) rats. We measured the femur and tibia length, growth plate area, proliferation of chondrocytes, and expression of insulin-like growth factor-1 (IGF-I) and IGF binding protein-3 (IGFBP-3), and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 5 (STAT5) phosphorylation after dietary administration of MH in SD rats for four weeks. The nose–tail length gain and length of femur and tibia increased significantly in the group that received MH for a period of four weeks. We performed H&E staining and Bromodeoxyuridine/5-Bromo-2′-Deoxyuridine (BrdU) staining to examine the effect of dietary administration of MH on the growth plate and the proliferation of chondrocytes and found that MH stimulated the proliferation of chondrocytes and contributed to increased growth plate height during the process of longitudinal bone growth. In addition, serum levels of IGF-1 and IGFBP-3 and expression of IGF-1 and IGFBP-3 mRNAs in the liver and bone were increased, and phosphorylation of JAK2/STAT5 in the liver was increased in the MH groups. Based on these results, we suggest that the effect of MH on longitudinal bone growth is mediated by increased JAK2/STAT5-induced IGF-1 production.

Pneumococcal infection is the main causative agent of pneumonia, meningitis, and sepsis in immunocompromised and elderly people. The samples in this study were collected from subjects in an 800‐bed hospital in Chungnam province, Korea, over the past 8 years. Of the 473,230 samples obtained for microbial culture from 2012 to 2019, Streptococcus pneumoniae was isolated from 714 samples collected from 702 patients, with a pneumococcal‐positive rate of 0.15%. We investigated the temporal, demographic, and specimen‐specific distributions, as well as the antibiotic susceptibility pattern for S. pneumonia. The age of patients ranged from 0 days to 98 years, with an average age of 64.7 years. The distribution among the sexes was 2.4 : 1 (male : female), with more samples isolated from male patients. We observed that spring was the predominant season in which the infection occurred, accounting for 37.6% of the cases. Pneumococci were most frequently isolated from sputum (608 cases, 85.2%). Invasive infections were detected at a rate of 66% (in blood cultures), and noninvasive infections were detected at a rate of 91% (in sputum cultures). Antimicrobial resistance to ceftriaxone, cefotaxime, erythromycin, tetracycline, clindamycin, cotrimoxazole, levofloxacin, and penicillin, based on noninvasive infections, was observed in 21.6%, 27.2%, 79.2%, 73.2%, 68.0%, 51.3%, 9.8%, and 18.1% of cases, respectively. Additionally, on average, 66.9% of multidrug‐resistant bacteria showed resistance to three or more antimicrobial agents, and 2.8% showed resistance to all other antibacterial agents except vancomycin. These results might facilitate the administration of appropriate empirical antibacterial therapy for pneumococcal infections.

Background: Acinetobacter baumannii is the causative agent in various types of hospital-acquired infections, including respiratory, urinary tract, and wound infections. Objectives: This study investigated the primary mechanisms underlying quinolone resistance in A. baumannii strains, isolated from samples collected from general hospitals. Methods: Ninety-eight strains of A. baumannii were isolated from clinical specimens from general hospitals from 2017 – 2019. Antimicrobial susceptibility, efflux pump inhibition tests, multilocus sequence typing (MLST), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses were conducted on 64 strains, and the blaoxa-51-like gene sequence was detected. Results: In the antimicrobial susceptibility test, 78.1% (n = 50) of the strains exhibited resistance to ciprofloxacin, a quinolone antibiotic, and 57.8% (n = 37) strains were multidrug resistant (MDR). For 18 strains, the minimum inhibitory concentration of ciprofloxacin reduced in presence of an efflux pump inhibitor. Sequence analysis revealed that in 50 strains of A. baumannii, the codon for serine (TCA) in gyrA was replaced by that for leucine (TTA), whereas in 43 strains, the codon for serine (TCG) in parC was replaced by that for leucine (TTG). Multilocus sequence typing analysis confirmed 18 sequence types, and allelic number analysis showed the presence of nine gyrB alleles, with gyrB3 showing the highest frequency (62.5%). Conclusions: The findings of this study will be useful in improving treatment efficiency and preventing the spread of A. baumannii (both MDR and non-MDR strains).