A case of Vagococcus fluvialis isolated from the bile of a patient with calculous cholecystitis.

BACKGROUND: Chronic cholecystitis, characterized by persistent inflammation of the gallbladder, predominantly stems from the prolonged presence of gallstones. Calculous cholecystitis has demonstrated a consistent escalation in its incidence over time.Gallbladder stones have been recognized as a predisposing factor for the development of biliary tract infections.Concomitantly, there have been substantial shifts in the distribution and resistance profiles of pathogenic microorganisms responsible for biliary tract infections. The timely acquisition of bile samples for pathogen analysis is of paramount importance, given its critical role in guiding judicious clinical pharmacotherapy and enhancing patient prognosis. CASE PRESENTATION: We present a case involving a 66-year-old female patient who had previously undergone subtotal gastrectomy due to diffuse large B-cell lymphoma. The patient was admitted to our institution with complaints of abdominal pain. Subsequent diagnostic evaluation revealed concurrent choledocholithiasis and cholecystolithiasis. The patient underwent surgical cholecystectomy as the therapeutic approach. Histopathological examination of the excised gallbladder disclosed characteristic features indicative of chronic cholecystitis. Subsequent laboratory analysis of the patient's bile specimen yielded Gram-positive cocci, subsequently identified through biochemical assays, mass spectrometry, and 16 S rRNA analysis as Vagococcus fluvialis. Further in vitro antimicrobial susceptibility testing using disk diffusion and microfluidic dilution showed that this strain exhibited inhibition zone diameters ranging from 12.0 to 32.0 mm in response to 26 antibiotics, including ampicillin, cefazolin, cefuroxime, cefotaxime, ceftriaxone, cefepime, ampicillin/sulbactam, piperacillin, ciprofloxacin, cefoperazone/sulbactam, imipenem, meropenem, piperacillin/tazobarb, penicillin, erythromycin, chloramphenicol, vancomycin, methotrexate/sulfamethoxazole, teicoplanin, linezolid, tigecycline, cefoxitin, ceftazidime, levofloxacin, minocycline and tobramycin. However, the inhibition zone diameters were 6.0 mm for amikacin, oxacillin, clindamycin, and tetracycline. The patient received ceftazidime anti-infective therapy both preoperatively and within 24 h postoperatively and was discharged successfully one week after surgery. CONCLUSION: In this study, we present the inaugural isolation and identification of Vagococcus fluvialis from bile specimens of patients afflicted with calculous cholecystitis. This novel finding lays a substantial experimental groundwork for guiding clinically rational antimicrobial therapy and advancing the exploration of relevant pathogenic mechanisms pertaining to Vagococcus fluvialis infections.

A Case of Weissella confusa Isolated from Blood of a Patient with Coronary Heart Disease Complicated with Gastrointestinal Bleeding.

Introduction: W. confusa has been known to cause various human infections. It is naturally resistant to vancomycin and is difficult to identify using traditional methods, which may lead to misidentification and delay treatment. Case Presentation: We present a case of a 42-year-old male patient with gastrointestinal bleeding and coronary heart disease who developed sepsis caused by Weissella confusa. The patient's blood cultures showed the presence of gram-positive coccobacilli, later identified as W. confusa through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing revealed that W. confusa had low minimum inhibitory concentrations (MICs) for some drugs (eg, ampicillin) and higher MICs for others (eg, cefotaxime). Empirical treatment with vancomycin was initially started, but after obtaining the identification and susceptibility results, the treatment was switched to meropenem combined with daptomycin, resulting in a successful outcome. Conclusion: Weissella confusa bacteremia is relatively rare, and accurate pathogenic diagnosis is essential for effective clinical treatment.

Evolution of carbapenem resistance in klebsiella pneumoniae and escherichia coli carrying blaNDM-1 gene: imipenem exposure results in sustained resistance memory of strains in vitro.

BACKGROUND: Antibiotics exert an outstanding selective pressure on bacteria, forcing their chromosomal gene mutations and drug resistance genes to spread. The objective of this study is to evaluate the expression of the New Delhi Metallo-ß-Lactamase-1 gene (blaNDM-1) in the clinical isolate (Klebsiella pneumoniae TH-P12158), transformant strains Escherichia coli BL21 (DE3)-blaNDM-1, and Escherichia coli DH5α- blaNDM-1 when exposed to imipenem. METHODS: ß-Lactamase genes (blaSHV, blaTEM-1, blaCTX-M-9, blaIMP, blaNDM-1, blaKPC, blaOXA, blaGES, and blaDHA) from randomly selected carbapenems-sensitive K.pneumoniae (n = 20) and E.coli (n = 20) strains were amplified by PCR. The recombinant plasmid of pET-28a harboring blaNDM-1 was transformed into E.coli BL21 (DE3) and E.coli DH5α by electroporation. The resistance phenotype and higher blaNDM-1 expression in K.pneumoniae TH-P12158, transformant E.coli BL21 (DE3)-blaNDM-1, and E.coli DH5α-blaNDM-1 were observed when exposed to imipenem with grade increasing, decreasing, and canceling doses, respectively. RESULTS: After being exposed to different doses of imipenem, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of antimicrobial drugs and blaNDM-1 expression of strains increased, which was positively correlated with doses of imipenem. On the contrary, with the decrease or cancellation of imipenem doses, the blaNDM-1 expression was deteriorated, while the MIC and MBC values remained relatively stable. These results demonstrated that low doses of imipenem (˂MIC) could press blaNDM-1 positive strains producing stable drug resistance memory and altered blaNDM-1 expression. CONCLUSIONS: Low doses of imipenem could press blaNDM-1 positive strains producing sustained resistance memory and altered blaNDM-1 expression. In particular, the positive correlation between the resistance genes expression and antibiotics exposure shows promising guiding significance for clinical medication.