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Globally, there have been increasing reports of antimicrobial resistance in nontyphoidal Salmonella (NTS), which can develop into severe and potentially life-threatening diarrhea. This study focuses on the synergistic effects of DNA gyrase mutations and plasmid-mediated quinolone resistance (PMQR) genes, specifically qnrB19, on fluoroquinolone (FQ) resistance in Salmonella Typhimurium. By utilizing recombinant mutants, GyrAS83F and GyrAD87N, and QnrB19's, we discovered a significant increase in fluoroquinolones resistance when QnrB19 is present. Specifically, ciprofloxacin and moxifloxacin's inhibitory concentrations rose 10- and 8-fold, respectively. QnrB19 was found to enhance the resistance capacity of mutant DNA gyrases, leading to high-level FQ resistance. Additionally, we observed that the ratio of QnrB19 to DNA gyrase played a critical role in determining whether QnrB19 could protect DNA gyrase against FQ inhibition. Our findings underscore the critical need to understand these resistance mechanisms, as their coexistence enables bacteria to withstand therapeutic FQ levels, posing a significant challenge to treatment efficacy.
RESUMEN
INTRODUCTION: The complete blood count (CBC) is a frequently performed laboratory test today. This study evaluated the effects of temperature and sample storage time on parameters of CBC which could produce misleading results of clinical significance. METHODS: In a cross-sectional study, CBC was checked in 102 randomly selected healthy individuals and baseline measurements were analyzed using the Sysmex XS 500i fully automated hematology analyzer. CBC was done on samples up to 48 hr of storage at temperatures of 4 ± 2°C, 23 ± 2°C, and 31 ± 2°C. Values were checked at time intervals of 6, 24, and 48 hr. RESULTS: Among CBC parameters, white blood cell, red blood cell, hemoglobin, mean cell hemoglobin (MCH), neutrophils and lymphocytes were stable at all three temperatures up to 48 hr. Monocytes, eosinophils, MCH concentration, hematocrit (Htc), and red cell distribution width-coefficient of variation showed statistically significant changes at 23 ± 2°C and 31 ± 2°C. A significant decline in platelet count (PLT) and increment in mean platelet volume and basophil count were seen at all study temperatures up to 48 hr. CONCLUSION: This study shows that most parameters of the CBC are unaffected with the studied storage temperature up to 48 hr except for the PLT which should be performed within 6 hr of the post-collection time. To avoid changes in a few parameters such as Htc, it is best to store the sample at 4 ± 2°C if any delay is anticipated.
