The spread of COVID-19 pandemic may have affected antibiotic consumption patterns and the prevalence of colonized or infected by multidrug-resistant (MDR) bacteria. We investigated the differences in the consumption of antibiotics easily prone to resistance and the prevalence of MDR bacteria during the COVID-19 pandemic (March 2020 to September 2021) compared to in the pre-pandemic period (March 2018 to September 2019). Data on usage of antibiotics and infections caused by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), carbapenem-resistant Enterobacteriaceae (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), and carbapenem-resistant Pseudomonas aeruginosa (CRPA) were obtained from hospitalized patients in four university hospitals. The consumption of penicillin with β-lactamase inhibitors (3.4% in ward, 5.8% in intensive care unit (ICU)), and carbapenems (25.9% in ward, 12.1% in ICU) increased during the pandemic period. The prevalence of MRSA (4.7%), VRE (49.0%), CRE (22.4%), and CRPA (20.1%) isolated in clinical samples from the ward and VRE (26.7%) and CRE (36.4%) isolated in clinical samples from the ICU were significantly increased, respectively. Meanwhile, only the prevalence of CRE (38.7%) isolated in surveillance samples from the ward increased. The COVID-19 pandemic is associated with increased consumption of antibiotics and has influenced the prevalence of infections caused by MDR isolates.

The prompt presumptive identification of methicillin-resistant Staphylococcus aureus (MRSA) using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) can aid in early clinical management and infection control during routine bacterial identification procedures. This study applied a machine learning approach to MALDI-TOF peaks for the presumptive identification of MRSA and compared the accuracy according to staphylococcal cassette chromosome mec (SCCmec) types. We analyzed 194 S. aureus clinical isolates to evaluate the machine learning-based identification system (AMRQuest software, v.2.1, ASTA: Suwon, Korea), which was constructed with 359 S. aureus clinical isolates for the learning dataset. This system showed a sensitivity of 91.8%, specificity of 83.3%, and accuracy of 87.6% in distinguishing MRSA. For SCCmec II and IVA types, common MRSA types in a hospital context, the accuracy was 95.4% and 96.1%, respectively, while for the SCCmec IV type, it was 21.4%. The accuracy was 90.9% for methicillin-susceptible S. aureus. This presumptive MRSA identification system may be helpful for the management of patients before the performance of routine antimicrobial resistance testing. Further optimization of the machine learning model with more datasets could help achieve rapid identification of MRSA with less effort in routine clinical procedures using MALDI-TOF MS as an identification method.

Seri Jeong, M.D., Kibum Jeon, M.D., Nuri Lee, M.D., Min-Jeong Park, M.D., and Wonkeun Song, M.D.. Ann Lab Med 2024;44:38-46. https://doi.org/10.3343/alm.2024.44.1.38

Seri Jeong, M.D., Nuri Lee, M.D., Min-Jeong Park, M.D., Kibum Jeon, M.D., Han-Sung Kim, M.D., Hyun Soo Kim, M.D., Jae-Seok Kim, M.D., and Wonkeun Song, M.D., Ph.D.. Ann Lab Med 2022;42:36-46. https://doi.org/10.3343/alm.2022.42.1.36

Viral gastroenteritis continues to be a leading cause of death in low-income countries. The impact of nonpharmaceutical interventions (NPIs) on the transmission of gastroenteritis-causing viruses during the COVID-19 pandemic is understudied. To investigate the 10-year trends of enteric viruses and estimate the impact of implementing and mitigating NPIs. Data regarding norovirus, rotavirus, adenovirus, astrovirus, and sapovirus detection were collected from five Korean hospitals between January 2013 and April 2023. We compared positivity between the pre-pandemic, pandemic, and post-pandemic periods. The causal effects of implementing and mitigating NPIs were quantified using the Bayesian Structural Time Series (BSTS) model. Norovirus was most frequently detected (9.9 %), followed by rotavirus (6.7 %), adenovirus (3.3 %), astrovirus (1.4 %), and sapovirus (0.6 %). During the pandemic, the positivity of all five viruses decreased, ranging from -1.0 % to -8.1 %, with rotavirus showing the greatest decrease. In the post-pandemic period, positivity rebounded for all viruses except for rotavirus. The BSTS model revealed that NPI implementation negatively affected the detection of all five viruses, resulting in reductions ranging from -73.0 % to -91.0 % compared to the prediction, with rotavirus being the least affected. Conversely, NPI mitigation positively affected the detection of all viruses, ranging from 79.0 % to 200.0 %, except for rotavirus. Trends observed over 10 years show that NPIs have had a major impact on changes in enteric virus detection. The effect of vaccines, in addition to NPIs, on rotavirus detection requires further investigation. Our findings emphasize the importance of NPIs in infection control and prevention.

Hypertrophic scarring (HTS) is a common complication of burns and has been associated with Slit2 protein. Slit2 plays various physiological and pathological roles in some body organs and tumors. However, its role in HTS development remains poorly understood. Therefore, this study investigated the involvement of intracellular and exogenous Slit2 in hypertrophic scar formation in vitro. Human normal fibroblasts (HNFs) and hypertrophic scar fibroblasts (HTSFs) were isolated from normal skin and hypertrophic scar tissues, respectively. Immunohistochemistry was conducted, and molecular expressions were detected by real-time polymerase chain reaction and western blotting. Cell proliferation and mobility were assessed. The results showed that Slit2 and Robo1 expressions were higher in the dermis of HTS tissues and HTSFs than in normal skin and HNFs. Downregulation of Slit2 expression by siRNA transfection reduced the expression of alpha-smooth muscle actin (α-SMA) and extracellular matrix in HTSFs. Additionally, treatment with recombinant Slit2 protein enhanced cell proliferation, expression of α-SMA, ECM, vimentin, N-cadherin, and migration by inducing the phosphorylation of both SMAD and non-SMAD signaling in HNFs. These findings highlight the active role of Slit2 in HTS formation, offer new insights into HTS pathology, and suggest Slit2 as a potential therapeutic target for post-burn hypertrophic scarring.