Susceptibility of Campylobacter Strains to Selected Natural Products and Frontline Antibiotics.

Noel Gahamanyi,Cheol-Ho Pan,Raghavendra G Amachawadi,Kye-Yoon Yoon,Leonard E.G Mboera,Dieudonné Mutangana,Mecky I Matee,Kwang Hyun Cha,Erick V.G Komba,Dae-Geun Song

doi:10.3390/antibiotics9110790

Abstract

Campylobacter species have developed resistance to existing antibiotics. The development of alternative therapies is, therefore, a necessity. This study evaluates the susceptibility of Campylobacter strains to selected natural products (NPs) and frontline antibiotics. Two C. jejuni strains (ATCC® 33560TM and MT947450) and two C. coli strains (ATCC® 33559TM and MT947451) were used. The antimicrobial potential of the NPs, including plant extracts, essential oils, and pure phytochemicals, was evaluated by broth microdilution. The growth was measured by spectrophotometry and iodonitrotetrazolium chloride. Antibiotic resistance genes (tet(O) and gyrA) were characterized at the molecular level. The minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) ranged from 25 to 1600 µg/mL. Cinnamon oil, (E)-Cinnamaldehyde, clove oil, eugenol, and baicalein had the lowest MIC and MBC values (25–100 µg/mL). MT947450 and MT947451 were sensitive to erythromycin and gentamicin but resistant to quinolones and tetracycline. Mutations in gyrA and tet(O) genes from resistant strains were confirmed by sequencing. The findings show that NPs are effective against drug-sensitive and drug-resistant Campylobacter strains. The resistance to antibiotics was confirmed at phenotypic and genotypic levels. This merits further studies to decipher the action mechanisms and synergistic activities of NPs.

Highlights

Campylobacter species, mainly C. jejuni and C. coli, are among the major pathogens causing human gastroenteritis [1]
The present study evaluates the susceptibility of Campylobacter strains to selected natural products (NPs) and frontline antimicrobials
A basic local alignment search tool (BLAST) analysis showed a 99% similarity between between C. coli from chicken (CC–CI) and C. coli YH502 (CP018900.1) isolated from retail chicken

Summary

Introduction

Campylobacter species, mainly C. jejuni and C. coli, are among the major pathogens causing human gastroenteritis [1]. Campylobacteriosis is of public health concern in low-, middle-, and high-income countries [2]. Biofilm formation in Campylobacter contributes to its resistance to environmental stress and Antibiotics 2020, 9, 0790; doi:10.3390/antibiotics9110790 www.mdpi.com/journal/antibiotics. Human infections with Campylobacter species occur via the ingestion of contaminated animal products or water [4,5,6]. There have been increased reports about high-level resistance to frontline and alternative antimicrobials, including macrolides, fluoroquinolones, aminoglycosides, and tetracyclines, among Campylobacter strains [7,8]. Increased antimicrobial resistance (AMR) among pathogens has been associated with many factors, including the unrestricted use of antimicrobials in various fields [9,10]

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