The distribution and antibiotic-resistant characteristics and risk factors of pathogens associated with clinical biliary tract infection in humans

Abstract

Introduction: Biliary Infection in patients is a common and important phenomenon resulting in severe complications and high morbidity, while the distributions and drug resistance profiles of biliary bacteria and related risk factors are dynamic. This study explored the characteristics of and risk factors for biliary infection to promote the rational use of antibiotics in clinically.

Methods: Bacterial identification and drug susceptibility testing were completed using the Vitek 2 Compact analysis system. The distribution and antibiotic-resistant characteristics of 3,490 strains of biliary bacteria in patients at Nankai Hospital from 2019 to 2021 were analyzed using Whonet 5.6 and SPSS 26.0 software. We then retrospectively analyzed the clinical data and risk factors associated with 2,340 strains of Gram-negative bacilli, which were divided into multidrug-resistant bacteria (1,508 cases) and non-multidrug-resistant bacteria (832 cases) by a multivariate Cox regression model.

Results and discussion: A total of 3,490 pathogenic bacterial strains were isolated from bile samples, including 2,340 (67.05%) Gram-negative strains, 1,029 (29.48%) Gram-positive strains, and 109 (4.56%) fungal strains. The top five pathogenic bacteria were Escherichia coli, Klebsiella pneumoniae, Enterococcus faecium, Enterococcus faecalis, and Pseudomonas aeruginosa. The rate of Escherichia coli resistance to ciprofloxacin increased (p < 0.05), while the resistance to amikacin decreased (p < 0.05). The resistance of Klebsiella pneumoniae to cephalosporins, carbapenems, β-lactamase inhibitors, cephalases, aminoglycosides, and quinolones increased (p < 0.05), and the resistance of Pseudomonas aeruginosa to piperacillin, piperacillin/tazobactam, ticacillin/clavulanic acid, and amicacin declined significantly (p < 0.05). The resistance of Enterococcus faecium to tetracycline increased by year (p < 0.05), and the resistance of Enterococcus faecalis to erythromycin and high-concentration gentamicin declined (p < 0.05). Multivariate logistic regression analysis suggested that the administration of third- or fourth-generation cephalosporins was an independent risk factor for biliary infection. In summary, Gram-negative bacilli were the most common pathogenic bacteria isolated from biliary infection patients, especially Escherichia coli, and the rates and patterns of drug resistance were high and in constant flux; therefore, rational antimicrobial drug use should be carried out considering risk factors.

Keywords: Gram-negative bacteria; biliary pathogens; distribution of bacteria; multidrug-resistant bacteria; risk factors.

Figure 1

The characteristics of distribution and proportion of pathogenic bacteria in patients with bile tract infection. The distribution and proportion of pathogenic bacteria in patients with bile tract infection in (A) 2019, (B) 2020, (C) 2021, and (D) 2019–2021 using double-layered pie charts. The inner layers in the pie charts were classified based on the proportion of aerobic Gram-positive bacteria, aerobic Gram-negative bacteria, fungi, and anaerobic bacteria. The outer pie charts showed the specific bacterial species under their respective categories.

Figure 2

The distribution of major pathogens in patients is seen in each of the top six clinical departments with a pie chart of double layers. The inner layers in the pie charts were classified according to the top six clinical departments. The outer pie charts displayed the top bacterial species under their respective departments.

Figure 3

Analysis of the rates of fermenting bacterial drug resistance. On the X-axis of all graphs are antimicrobial agents for Gram-negative bacteria, while the Y-axis displays the percentage of resistant bacterial strains. (A) Analysis of Escherichia coli drug resistance in bile tract infection patients during 2019–2021. Upper left: Escherichia coli drug resistance in 2019. Upper right: Escherichia coli drug resistance in 2020. Left bottom: Escherichia coli drug resistance in 2021. Right bottom: Escherichia coli drug resistance during 2019–2021. (B) Analysis of Klebsiella pneumoniae drug resistance in patients with bile tract infection patients during 2019–2021. Upper left: Klebsiella pneumoniae drug resistance in 2019. Upper right: Klebsiella pneumoniae drug resistance in 2020. Left bottom: Klebsiella pneumoniae drug resistance in 2021. Right bottom: Klebsiella pneumoniae drug resistance during 2019–2021.

Figure 4

Analysis of the rates of non-fermenting bacterial drug resistance. Rates of Pseudomonas aeruginosa drug resistance in (A) 2019, (B) 2020, (C) 2021, and (D) 2019–2021. The X-axis of all the graphs displays antimicrobial agents, while the Y-axis represents the percentage proportions of resistant bacteria strains.

Figure 5

Characteristics of major Gram-positive bacterial drug resistance. The X-axis of all graphs represents antimicrobial agents for Gram-positive bacteria, while the Y-axis depicts the percentages of resistant bacterial strains. (A) Analysis of Enterococcus faecium drug resistance in patients with bile tract infection during 2019–2021. Upper left: Enterococcus faecium drug resistance in 2019. Upper right: Enterococcus faecium drug resistance in 2020. Left bottom: Enterococcus faecium drug resistance in 2021. Right bottom: Enterococcus faecium drug resistance during 2019–2021. (B) Enterococcus faecalis drug resistance in patients with bile tract infection during 2019–2021. Upper left: Enterococcus faecalis drug resistance in 2019. Upper right: Enterococcus faecalis drug resistance in 2020. Left bottom: Enterococcus faecalis drug resistance in 2021. Right bottom: Enterococcus faecalis drug resistance during 2019–2021.