ObjectiveTo study the distributions of virulence genes of Klebsiella pneumoniae (KP) and the distribution of hypervirulent KP (HvKP), and assess the performance of a single gene to predict HvKP.MethodsPolymerase chain reaction (PCR) method was used to analyze 12 virulence-related genes (entB, irp2, iroN, iucA, mrkD, fimH, c-rmpA, p-rmpA2, p-rmpA, wzy-K1, allS and peg-344) and drug-resistance gene blaKPC among 376 clinical KP strains collected from January 2016 to December 2018. Sequence types (ST) of KP were determined after sequencing and comparison, following the detection of 7 house-keeping genes (gapA, infB, mdh, pgi, phoE, rpoB and tonB) by PCR method. Statistical analyses were made for the distributions of virulence genes of KP and the distribution of HvKP with GraphPad Prism 8 software.ResultsAmong the 376 KP strains, the positive rates of entB, irp2, iroN, iucA, mrkD, fimH, c-rmpA, p-rmpA2, p-rmpA, wzy-K1, allS and peg-344 were 100.0%, 76.9%, 22.1%, 28.2%, 97.6%, 97.1%, 1.6%, 24.5%, 21.0%, 7.4%, 4.8% and 31.6%, respectively. The positive rates of the aforementioned virulence genes in the blaKPC-positive group (n=167) were 100.0%, 94.0%, 7.2%, 16.8%, 97.0%, 96.4%, 0.0%, 15.0%, 6.6%, 0.0%, 0.0% and 21.0%, respectively, and those in the blaKPC-negative group (n=209) were 100.0%, 63.2%, 34.0%, 37.3%, 98.1%, 97.6%, 2.9%, 32.1%, 32.5%, 13.4%, 8.6% and 40.2%, respectively; there was no statistically significant difference in entB, mrkD or fimH between the two groups (P>0.05), the positive rate of irp2 was higher in the blaKPC-positive group than that in the blaKPC-negative group (P<0.05), and the positive rates of the rest virulence-related genes were lower in the blaKPC-positive group than those in the blaKPC-negative group (P<0.05). The rate of HvKP in the blaKPC-negative group was higher than that in the blaKPC-positive group (38.3% vs. 18.0%, P<0.05). As a marker of HvKP, iucA showed high sensitivity and specificity (90.9% and 97.7%), followed by p-rmpA2 (83.6% and 100.0%) and iroN (73.6% and 99.2%). ST11 accounted for 87.4% in the blaKPC-positive group, while ST23, ST20, ST54 and ST29 were the four primary types in the blaKPC-negative group, accounting for 23.4% totally.ConclusionsDifferent virulence genes mean different distributions in KP. blaKPC-negative KP is more virulent than blaKPC-positive KP. iucA and p-rmpA2 could serve as good predicators of HvKP. Armed with extreme virulence and drug-resistance, blaKPC-positive HvKP is of great clinical concern.
Objective
To probe the distribution and drug resistance of pathogens causing surgical site infection in patients after gynecologic operation, and provide reference for prevention and treatment.
Methods
Seventy patients with incision infection after gynecologic operation in West China Second University Hospital of Sichuan University from January 2010 to May 2015 were selected. Species of the pathogens from the submitted specimens and the results of the drug susceptibility testing were analyzed.
Results
Seventy-two strains of pathogens were isolated, including 36 strains (50.0%) of Gram-negative (G–) bacteria and 36 strains (50.0%) of Gram-positive (G+) bacteria. The main G– bacteria were Escherichia coli (36.1%) and Enterobacter cloacae (5.6%); the main G+ bacteria were Staphylococcus aureus (18.1%), Staphylococcus epidermidis (12.5%), and Enterococcus faecalis (8.3%). Escherichia coli showed low sensitivities to ampicillin, ceftriaxone, and gentamicin, with resistance rates of 76.9%, 61.5%, and 61.5%, respectively. Staphylococcus aureus showed low sensitivities to penicillin G, clindamycin, and erythromycin, with resistance rates of 92.3%, 69.2%, and 61.5%, respectively. Staphylococcus epidermidis showed low sensitivities to erythromycin, penicillin G, and ciprofloxacin, with resistance rates of 88.9%, 77.8%, and 77.8%, respectively. No carbapenem-resistant G– bacteria or vancomycin-resistant G+ bacteria were detected.
Conclusion
Postoperative surgical site infection is the most common nosocomial infection. The main bacteria related to postoperative incision infection in the gynecology department of the hospital are Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis, which become resistant to common antibiotics currently. Therefore more attention should be paid to bacterial isolation and drug susceptibility test results for rational use of antimicrobial drugs and effectiveness of the treatment to nosocomial infection.
