Human and avian extraintestinal pathogenic Escherichia coli: infections, zoonotic risks, and antibiotic resistance trends

Abstract

Extraintestinal pathogenic Escherichia coli (ExPEC) constitutes ongoing health concerns for women, newborns, elderly, and immunocompromised individuals due to increased numbers of urinary tract infections (UTIs), newborn meningitis, abdominal sepsis, and septicemia. E. coli remains the leading cause of UTIs, with recent investigations reporting the emergence of E. coli as the predominant cause of nosocomial and neonatal sepsis infections. This shift from the traditional Gram-positive bacterial causes of nosocomial and neonatal sepsis infections could be attributed to the use of intrapartum chemoprophylaxis against Gram-positive bacteria and the appearance of antibiotic (ATB) resistance in E. coli. While ExPEC strains cause significant healthcare concerns, these bacteria also infect chickens and cause the poultry industry economic losses due to costs of containment, mortality, and disposal of carcasses. To circumvent ExPEC-related costs, ATBs are commonly used in the poultry industry to prevent/treat microbial infections and promote growth and performance. In an unfortunate linkage, chicken products are suspected to be a source of foodborne ExPEC infections and ATB resistance in humans. Therefore, the emergence of multidrug resistance (MDR) (resistance to three or more classes of antimicrobial agents) among avian E. coli has created major economic and health concerns, affecting both human healthcare and poultry industries. Increased numbers of immunocompromised individuals, including the elderly, coupled with MDR among ExPEC strains, will continue to challenge the treatment of ExPEC infections and likely lead to increased treatment costs. With ongoing complications due to emerging ATB resistance, novel treatment strategies are necessary to control ExPEC infections. Recognizing and treating the zoonotic risk posed by ExPEC would greatly enhance food safety and positively impact human health.

FIG. 1.

Avian and human extraintestinal pathogenic Escherichia coli (ExPEC), their infections, and zoonotic potential. The schematic diagram illustrates the major ExPEC pathotypes and their infections in humans and birds. ExPEC can cause localized infections that can become systemic (urinary tract infection [UTI] in humans and airsacculitis in birds), a systemic infection that localizes (meningitis), both a local and systemic infection (salpingitis in birds), or localized only (cellulitis in birds). The diagram also shows the potential of poultry and their products to transfer antibiotic (ATB) resistance and ExPEC to humans and cause zoonotic diseases. UPEC, uropathogenic Escherichia coli; NMEC, neonatal meningitis E. coli; SEPEC, sepsis E. coli; APEC, avian pathogenic E. coli. Color images available online at www.liebertpub.com/fpd