In order to define the contributions of the mechanisms for carbapenem resistance in clinical strains of Pseudomonas aeruginosa, we investigated the presence of OprD, the expressions of the MexAB-OprM and MexEF-OprN systems, and the production of the ␤-lactamases for 44 clinical strains. All of the carbapenemresistant isolates showed the loss of or decreased levels of OprD. Three strains overexpressed the MexABOprM efflux system by carrying mutations in mexR. These three strains had the amino acid substitution in MexR protein, Arg (CGG) 3 Gln (CAG), at the position of amino acid 70. None of the isolates, however, expressed the MexEF-OprN efflux system. For the characterization of ␤-lactamases, at least 13 isolates were the depressed mutants, and 12 strains produced secondary ␤-lactamases. Based on the above resistance mechanisms, the MICs of carbapenem for the isolates were analyzed. The MICs of carbapenem were mostly determined by the expression of OprD. The MICs of meropenem were two-to four-fold increased for the isolates which overexpressed MexAB-OprM in the background of OprD loss. However, the elevated MICs of meropenem for some individual isolates could not be explained. These findings suggested that other resistance mechanisms would play a role in meropenem resistance in clinical isolates of P. aeruginosa.Pseudomonas aeruginosa is a clinically important pathogen with intrinsic resistance to various antimicrobial agents. This intrinsic multidrug resistance results from the synergy between broadly specific drug efflux pumps and a low degree of outer membrane permeability. For the carbapenem antimicrobials, the resistance is mostly mediated by OprD loss, which primarily confers a resistance to imipenem but also confers a low grade resistance to meropenem (12,16). But the multidrug efflux systems which mediate the resistance to quinolone, chloramphenicol, and many other antimicrobial agents, also contribute to the carbapenem resistance. The strains which overexpress the MexAB-OprM system or express the MexEFOprN system exhibit the carbapenem resistance by pumping the drug out or repressing the transcription of oprD, respectively (13,20,25). On the other hand, the NfxB mutants which expressed MexCE-OprJ became more susceptible to imipenem, bipenem, and some ␤-lactams (22). In addition to the OprD loss or drug efflux pumps, chromosomal AmpC ␤-lactamase plays an important role in carbapenem resistance in P. aeruginosa (16,21). Although the contributions of the OprD loss, the efflux systems, and ␤-lactamase in the carbapenem resistance have been well characterized in the laboratory strains, little data is available for how such factors play together in the clinical isolates of P. aeruginosa (2,4,31).Based on the carbapenem susceptibility patterns, the clinical isolates of carbapenem-resistant P. aeruginosa could be divided into three groups as the imipenem-resistant and meropenemsensitive group, the imipenem-sensitive and meropenem-resistant group, and the imipenem-resistant and meropenem-resistant group (2,4,17)...

Background We performed a prospective survey on the adverse reactions following the first dose of two types of vaccines against coronavirus disease 2019 (COVID-19) in healthcare workers (HCWs) in South Korea. Methods HCWs at a tertiary referral hospital in Seoul, South Korea, received a chimpanzee adenovirus-vectored vaccine (ChAdOx1 nCoV-19) or an mRNA-based vaccine (BNT162b2) between March 5 and March 26, 2021. The HCWs were asked to report adverse reactions through a mobile self-report questionnaire for three days after vaccination. Results A total of 7,625 HCWs received the first dose of ChAdOx1 or BNT162b2 vaccine during the study period. Of them, 5,866 (76.9%) HCWs (ChAdOx1, n = 5,589 [95.3%]; BNT162b2, n = 277 [4.7%]) participated at least once in the survey, of whom 77% were female and 86% were younger than 50 years. The overall adverse reaction rate was 93% in the ChAdOx1 group and 80% in the BNT162b2 group ( P < 0.001). Both local and systemic reactions were more commonly reported in the ChAdOx1 group, and the difference was larger in systemic reactions such as fever and fatigue. In the ChAdOx1 group, the incidence of adverse reactions was significantly higher in females and those in the younger age groups, while the BNT162b2 group showed such difference according to age. Conclusion In our prospective survey, vaccine-associated adverse reactions were more commonly reported in the ChAdOx1 group than in the BNT162b2 group. Females and younger age groups experienced vaccine-associated adverse reactions more frequently.

BackgroundOpioids are widely used in boluses and patient-controlled analgesia (PCA) for postoperative pain control. In this study, we compared the effects of oxycodone and fentanyl on postoperative pain in patients with intravenous patient-controlled analgesia (IV-PCA) after laparoscopic gynecological surgery.MethodsSeventy-four patients undergoing elective total laparoscopic hysterectomy or laparoscopic myomectomy were randomly assigned to the administration of either fentanyl or oxycodone using IV-PCA (potency ratio 1 : 60). The cumulative dose administered in the patient-controlled mode during the initial 48 hours after the operation was measured. Patients were also assessed for postoperative pain severity, adverse effects, and patient satisfaction.ResultsNo significant differences were observed in patient satisfaction with the analgesia during the postoperative period. Patients in the oxycodone group experienced significantly more dizziness compared to the fentanyl group. Patients in the oxycodone group showed significantly lower consumption of opioid in the patient-controlled mode (10.1 ± 8.5 ml vs. 16.6 ± 12.0 ml, P = 0.013).ConclusionsOur data suggest that oxycodone and fentanyl demonstrated similar effects, and therefore oxycodone may be a good alternative to fentanyl in postoperative pain management. Further studies in various clinical settings will be needed to determine the adequate potency ratio.