Susceptibility of Campylobacter Strains to Selected Natural Products and Frontline Antibiotics

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.

Peroral Clove Essential Oil Treatment Ameliorates Acute Campylobacteriosis—Results from a Preclinical Murine Intervention Study

“…Although the underlying mechanisms were not in the focus of our investigations, direct antipathogenic effects of clove EO are supported by the earlier findings that clove EO is able to kill C. jejuni and other bacteria by the concerted action of membrane destruction and intracellular ROS formation. By the application of 5 g/L clove EO in drinking water we assured that the drug concentrations taken up by infected mice were above the minimum inhibitory concentration (MIC) values which are required to kill C. jejuni in vitro [ 29 ]. This was further confirmed by the MIC of eugenol constituting the major compound of clove EO against the C. jejuni strain 81-176 (i.e., 0.1 g/L; data not shown).…”

“…Furthermore, a treatment option of interest should in parallel dampen innate immune responses with a minimal risk of unwanted side effects. Clove essential oil (EO) appeared as a promising candidate since it has been shown to exert antimicrobial activity against C. jejuni [ 29 ] and other bacterial pathogens mainly by disruption of the outer membrane and by the production of intracellular ROS in the bacteria [ 30 , 31 ]. Furthermore, recent studies revealed that coincubation of C. jejuni with clove EO and its major compound eugenol resulted in compromised pathogenic motility, disturbed spiral-shaped morphology, and diminished virulence factor expression, all of which required for induction of campylobacteriosis [ 11 , 31 , 32 , 33 , 34 ].…”

Genomic Characterization of Fluoroquinolone-Resistant Thermophilic Campylobacter Strains Isolated from Layer Chicken Feces in Gangneung, South Korea by Whole-Genome Sequencing

“…The two Campylobacter strains used in this study were selected from our previously published research work [8]. For this experiment, preserved strains were revived by inoculating them onto Mueller Hinton Agar as previously described [33].…”

“…Chicken ceca are colonized by high levels of Campylobacter which may persist in feces that are used as biofertilizers [7]. Human campylobacteriosis is of public health concern due to the increased number of Campylobacter strains that are resistant to both drugs of choice (macrolides and fluoroquinolones) and alternative therapies (aminoglycosides and tetracyclines) [8]. The missense mutation (C257T) in the quinolone resistance-determining region (QRDR) of gyrA has been associated with high-level resistance to quinolones [9].…”

Inhibitory Effect of Puroindoline Peptides on Campylobacter jejuni Growth and Biofilm Formation

“…Antibiotic-resistant C. jejuni isolates have been observed and reported in recent years (Marotta et al, 2020;Tang et al, 2020;Hull et al, 2021). A recent study reported that some natural products, including plant extracts, essential oils, and pure phytochemicals, are effective against drug-sensitive and drug-resistant Campylobacter strains (Gahamanyi et al, 2020). These natural products can be used alone or in combination to kill C. jejuni.…”