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.

Nosocomial outbreak due to carbapenem-resistant Enterobacteriaceae has become serious challenge to patient treatment and infection control. We describe an outbreak due to a multidrug-resistant Providencia rettgeri from January 2016 to January 2017 at a University Hospital in Seoul, Korea. A total of eight non-duplicate P. rettgeri isolates were discovered from urine samples from eight patients having a urinary catheter and admitted in a surgical intensive care unit. The β-lactamase genes were identified using polymerase chain reaction and direct sequencing, and strain typing was done with pulsed-field gel electrophoresis (PFGE). All isolates showed high-level resistance to extended-spectrum cephalosporins, aztreonam, meropenem, ertapenem, ciprofloxacin, and amikacin. They harbored the blaNDM-1 carbapenemase and the blaPER-1 type extended-spectrum β-lactamases genes. PFGE revealed that all isolates from eight patients were closely related strains. The 13-month outbreak ended following reinforcement of infection control measures, including contact isolation precautions and environmental disinfection. This is the first report of an outbreak of a P. rettgeri clinical isolates co-producing NDM-1 and PER-1 β-lactamase.

We quantitatively analyzed SARS-CoV-2 antibody levels in patients after two doses of the ChAdOx1 nCoV-19 vaccine and the third BNT162b2 booster. We obtained 255 serum samples from 149 healthcare workers 1 and 4 months after the third dose. Of the 149 participants, 58 (38.9%) experienced COVID-19 infection during the 4-month study period, with infection occurring 7–62 days before the second blood draw. Total antibody titers against the anti-spike (anti-S) and anti-nucleocapsid (anti-N) proteins of SARS-CoV-2 were measured using Elecsys Anti-SARS-CoV-2 S and Elecsys Anti-SARS-CoV-2 assays (Roche), respectively. The median anti-S antibody titer in the non-infected groups at 4 months after the third dose was significantly decreased compared to that at 1 month after the third dose (from 17,777 to 3673 U/mL, p < 0.001). The infected group showed higher median anti-S antibody titers at 4 months (19,539 U/mL) than the non-infected group (3673 U/mL). The median anti-N antibody titer in the infected group at 4 months after the third dose was a 5.07 cut-off index (79.3% positivity). Anti-N antibody titers in the infected group were correlated with the number of days after SARS-CoV-2 infection. These data provide useful information for determining quarantine strategies and fourth vaccination requirements.

Noh JY, et al. J Korean Med Sci. 2020 Jul;35(33):e311. https://doi.org/10.3346/jkms.2020.35.e311

Free light chains (FLCs) are useful biomarkers for the diagnosis and monitoring of various plasma cell dyscrasias. One hundred fifty-seven samples from 120 patients for screening or monitoring of monoclonal gammopathy (MG) were included. The new N Latex FLC assays (Siemens Healthcare Diagnostics GmbH, Germany) were compared with the Freelite FLC assays (The Binding Site Ltd., UK) and the results were analyzed with those of immunofixation electrophoresis (IFE). The Freelite FLC assay showed significantly wider assay ranges than the N Latex FLC assay. The correlation coefficients of the two FLC kappa (κ) assays, lambda (λ) assays, and theκ/λratio were 0.9792, 0.8264, and 0.9064, respectively. The concordance rate was 84.7% for the FLCκassays, 79.6% for FLCλ, and 89.2% for theκ/λratio. The clinical sensitivity and specificity of theκ/λratios were 72.2% and 93.6% for the Freelite assay and 64.6% and 100% for the N Latex FLC assay. Two FLC assays showed good correlations and concordance. However, the clinical sensitivity of theκ/λratio was higher in the Freelite FLC assays; clinical specificity was higher in the N Latex FLC assay. Both FLC assays seem to have limited clinical utility in detecting MG in certain clinical settings.