Risk Factors for Mortality, Antibiotic Resistance in E coli Bloodstream Infection

E. coli bacteria. Computer illustration of Escherichia coli bacteria. E. coli is a rod- shaped bacterium (bacillus). Its cell membrane is covered in fine filaments called pili or fimbriae. Hair-like structures called flagella at the rear of each bacterium provide propulsion to make it move. E. coli is a normal component of the intestinal bacterial flora, but under certain conditions some strains can cause severe infections such as gastroenteritis.
What risk factors affect ESBL-producing bacterial infection, and what factors are associated with its prognosis and with its resistance to antibiotics?

Extended-spectrum β-lactamase (ESBL)–producing Escherichia coli has been shown to be more prevalent in patients with nosocomial infection, biliary tract infection, stomach tube catheterization, and prior cephalosporin administration. A retrospective analysis was conducted among patients with an E coli bloodstream infection from a primary hospital in East China. Results of the analysis were published in the European Journal of Clinical Microbiology & Infectious Diseases.

Recognizing that the epidemiologic data on E coli bloodstream infection has been poorly described, the researchers sought to explore the risk factors that affect ESBL-producing bacterial infection and are associated with the prognosis of patients with such an infection. Further, they evaluated the risk factors related to antibiotic resistance and mortality. Although an increasing number of functional single-nucleotide polymorphisms (SNPs) were shown to be associated with the clinical outcome of sepsis, the SNPs that affect the risk for mortality in Chinese patients with E coli bloodstream infection have been rarely explored.

Adult patients with an E coli bloodstream infection, based on a primary disease, were enrolled in the current study between January 2012 and December 2015. A total of 388 patients were included in the study. The first positive sample from each patient was utilized for the test of antimicrobial susceptibilities and ESBL. Hospital-acquired infections were defined as those that were acquired at the hospital at least 48 hours following admission. The genes that encoded β-lactamases were detected with the use of polymerase chain reaction.

Among all E coli isolates from the enrolled patients, 40.98% (159 of 388) of them were ESBL-positive. Per univariate analysis, nosocomial infection, urinary tract infection, biliary tract infection, diabetes, urinary catheterization, stomach tube catheterization, and cephalosporin use within 30 days were shown to be significantly associated with infection from ESBL-producing E coli.

Based on multiple analyses, nosocomial infection (odds ratio [OR], 1.79; 95% CI, 1.21-3.54), biliary tract infection (OR, 1.35; 95% CI, 1.13-2.25), stomach tube catheterization (OR, 2.41; 95% CI, 1.63-5.49), and prior cephalosporin administration (OR, 2.08; 95% CI, 1.22-5.98) were identified as being independent risk factors for ESBL-producing E coli.

Most of the E coli isolates were susceptible to carbapenem and β-lactam/β-lactamase inhibitor combinations. Only 0.52%, 0.93%, and 2.84% of isolates showed in vitro resistance to imipenem, ertapenem, and piperacillin/tazobactam, respectively. Regarding non-carbapenem and non–β-lactam antibiotics, the highest resistance was recorded for ampicillin/sulbactam (49.52%) and the lowest resistance was recorded for amikacin (1.55%).

The major ESBL genes observed were CTX-M-14, CTX-M-55, CTX-M-15, and CTX-M-27. The percentage of CTX-M-15 was significantly higher in patients older than 70 years of age and in those who underwent stomach tube catheterization. Overall, 2 genetic polymorphisms linked to inflammation activation — rs231775 A allele and rs2233406 T allele — were associated with a significantly increased mortality risk for E coli bloodstream infection (risk ratio [RR], 1.93; 95% CI, 1.05-3.55 and RR, 4.38; 95% CI, 2.07-9.29, respectively).

Limitations of the current analysis include the fact that it was a single-center study, with a small sample size and restricted ethnicity. Further, the effects of treatment for other underlying diseases were difficult to assess comprehensively; thus, the bias induced by the treatment of underlying diseases might influence the results.

The investigators concluded that patients with risk factors for E coli bloodstream infection should be monitored strictly, with invasive procedures minimized in this population. Both rs231775 and rs2233406 are promising prognostic markers for patients with E coli bloodstream infection.

Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.  


Zhao S, Wu Y, Dai Z, Chen Y, Zhou X, Zhao J. Risk factors for antibiotic resistance and mortality in patients with bloodstream infection of Escherichia coli. Eur J Clin Microbiol Infect Dis. Published online February 21, 2022. doi:10.1007/s10096-022-04423-6      

This article originally appeared on Pulmonology Advisor