Abstract
The presence of virulence factors (VFs) and mechanisms of quinolones and macrolide resistance was analyzed in Campylobacter spp. from a pediatric cohort study in Lima. In 149 isolates (39 Campylobacter jejuni and 24 Campylobacter coli from diarrheic cases; 57 C. jejuni and 29 C. coli from controls), the presence of the cdtABC and cadF genes and iam marker was established. Nalidixic acid, ciprofloxacin, erythromycin, and azithromycin susceptibilities were established in 115 isolates and tetracycline-susceptibility was established in 100 isolates. The presence of mutations in the gyrA, parC, and 23S rRNA genes was determined. The cadF gene and all genes from the cdtABC operon were significantly more frequent among C. jejuni (P < 0.0001); the iam marker was more frequent in C. coli (P < 0.0001). No differences were observed in VFs between cases and controls. Almost all isolates were tetracycline-resistant; nalidixic acid and ciprofloxacin resistance reached levels of 90.4% and 88.7%, respectively. Resistance to macrolides was 13% (C. jejuni 4.3%; C. coli 26.1%). Resistance to ciprofloxacin was related to GyrA Thr86 substitutions, while 13 of 15 macrolide-resistant isolates possessed a 23S rRNA mutation (A2075G). Differences in the presence of VFs and alarming levels of resistance to tested antimicrobial agents were observed among C. jejuni and C. coli.
Highlights
Campylobacter spp. ranks among the most relevant causes of diarrheal illness worldwide, with recent estimations of around 166,000 cases/year, including 31,700 Guillain-Barre Syndromes, which lead to 37,604 deaths and 3,733,822 Disability Adjusted Life Years (DALYs) [1]
The aim of this study was to determine the presence of several virulence factors (VFs) and the levels and molecular mechanisms of resistance to quinolones and macrolides in a series of Campylobacter spp. isolates recovered from children less than 18 months of age, in a periurban area of Lima, Peru
The results showed almost full concordance and extremely high levels of resistance (104 isolates, 90.4% to Nal; 102 isolates, 88.7% to Cip)
Summary
Campylobacter spp. ranks among the most relevant causes of diarrheal illness worldwide, with recent estimations of around 166,000 cases/year, including 31,700 Guillain-Barre Syndromes, which lead to 37,604 deaths and 3,733,822 Disability Adjusted Life Years (DALYs) [1]. Relatively little is known about the virulence of Campylobacter spp., these microorganisms possess different virulence factors (VFs) related to motility, adhesion, invasion, toxin-activity, immune evasion, and iron-uptake, among others [2]. While factors, like the cadF gene or the iam locus, are involved in different invasion steps [4, 5] others such as the cytolethal distending toxin, a tripartite toxin encoded in the cdtA, cdtB, and cdtC genes which is present in other microorganisms [6], block the CDC2 kinase, leading to progressive cellular distension which results in cell death [2]. The presence of quinolone-resistant Campylobacter spp. isolates is not a novel event [8,9,10].
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