High level of colonization with third-generation cephalosporin-resistant Enterobacterales in African community settings, Ghana

The variety of β-lactamase enzymes, with their increasing substrate diversity and wide dissemination, constitute the most important antimicrobial-resistant mechanism in gram-negative bacteria [1,2]. Of these enzymes, the most clinically important are ESBLs and AmpCs that hydrolyze most penicillins and cephalosporins but not carbapenems; and lately, the carbapenemases that may inactivate carbapenems together with other beta-lactam antimicrobials. The class D carbapenemases of blaOXA-48 type however hydrolyze carbapenems poorly, but not the extended-spectrum cephalosporins. Often these enzymes appear in multidrug-resistant Escherichia coli and Klebsiella pneumoniae that additionally are resistant to other classes of antibiotics. E. coli strains may be assigned to 1 of the 8 phylogroups (A, B1, B2, C, D, E, F, and the Escherichia cryptic clade I [3]. Strains of these groups may differ in virulence potential depending on their phylogenetic profiles [4,5].

Recently the association of ESBLs, AmpCs, and carbapenemases with epidemic clones of Enterobacterales have increasingly gained prominence. The most notable of these is the fluoroquinolone-resistant E. coli O25b-ST131 clone which is of significant public health concern because of its predominantly multidrug-resistant phenotype, and rapid dissemination as a worldwide pandemic clone. The spread of these pathogens in the community presents a huge public health concern [6,7]. Most gut colonization studies in the community have focused on ESBLs [1,2], and a few on carbapenemases [8], whilst reports of AmpCs in commensal isolates from healthy community persons are uncommon [9]. Only rarely did studies appropriately measure the occurrence of fecal isolates of cephalosporin-resistant Enterobacterales in an African community setting. A single study reported in parallel the fecal carriage of ESBL-, AmpC-, and carbapenemase-producing E. coli or K. pneumoniae in noninstitutionalized persons [10,11]. In Ghana, monitoring of antibiotic use is poor, with nascent surveillance systems and scarce reporting. In a recent commentary on antibiotic resistance in Ghana, Gyansa-Lutterodt identified a strategic need to build capacity for research into key issues related to antibiotic resistance [12]. In 2009, the ADMER program was initiated to strengthen the surveillance of antimicrobial resistance in Ghana. One of its objectives was to build research capacity and determine the prevalence, molecular characterization, and factors associated with cephalosporin-resistant Enterobacterales in Ghana. This is crucial for monitoring emerging trends in resistance at the local level to support clinical management.

In this study, we report the occurrence of cephalosporin-resistant E. coli and K. pneumoniae—with a particular focus on genotypes of plasmid-mediated ESBLs, AmpCs, and carbapenemases. The presence of phylogenetic clones was assessed and the emerging O25b:ST131 clone was determined. Furthermore, risk factors for intestinal colonization with these resistant bacteria were analyzed.

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