Introduction of antimicrobial susceptibility testing to Campylobacter species and sub-species.

Abstract

Antibiotic resistance, particularly with the fluoroquinolones and macrolide antibiotics, has now emerged globally with thermophilic campylobacters, including mainly Campylobacter jejuni and Campylobacter coli, giving rise to concerns about how these organisms have acquired such resistance characteristics, as well as consequences for human and animal treatment. Currently, Campylobacter is the leading enteropathogenic organism worldwide. Generally, in animals this organism causes no harm, but in humans it causes campylobacteriosis with a number of side effects including the Guillian-Barre virus. It is contracted through many sources such as private reservoirs and unpasteurised milk but mainly through ingested food. Campylobacter is a zoonotic disease. Malta, having the smallest amount of broilers, when compared to the rest of Europe, sports one of the highest percentages of Campylobacter isolation from chicken carcasses. This organism and the resistance associated with the strain are both transferred to humans. Therefore, resistance acquired through the ingestion of animal feed with antibiotics (as growth promoters), is transferred to humans through the zoonotic cycle. In order to establish the Maltese setting when compared with Europe, a series of procedures were carried out. Through the period of June 2008-June 2010, all Campylobacter strains (156 isolates) were collected from human stool samples received in the Bacteriology Laboratory at Mater Dei Hospital which is the main Maltese General Hospital and also the only teaching hospital in Malta. Each Campylobacter strain was subjected to a series of five main antibiotics and the MICs of each was established. Through this, sensitive/resistance patterns of each antibiotic was achieved and was compared with the European status. Mean Inhibitory Concentration data was achieved using the E-strip method and identification was done through conventional methods.

It was established that the Maltese picture is on the same baseline as that of Europe, comparatively. Through the results of the 156 isolates analyzed, evidence of the main predominance of groups affected by this organism was established. The most age group affected was the youngest group (0-10 years). In addition to this, the male sub-group showed a slightly higher incidence when compared to the female group. Although the summer season showed a peak of infectious incidence, a confluent incidence of infection was determined throughout all months of the two year period of this study. When analyzing the sensitiveresistant patterns, Erythromycin, Gentamicin and Meropenem showed quite a high sensitivity in all strains. Even when a breakdown of each sub-species was analyzed, Erythromycin remained one of the most sensitive antibiotics tested against. Although Campylobacter coli showed much more resistance than Campylobacter jejuni, Erythromycin, Gentamicin and Meropenem remained on the sensitive side, with Ciprofloxacin and Tetracycline showing quite a pattern of resistance. Further analysis was done to compare resistance between the two gender groups (male vs females) and also between two main age-groups (0-15 years in one group and 16-above in another group). Through this comparison, the younger age group (0-15 years) had the highest amount of resistant strains when compared to the older generation. On the other hand, females showed a lower sensitivity trend when compared to the male group. These results are of great importance due to the fact that on a larger scale study, there may actually be a definite trend of resistance between age groups and gender. This data further emphasizes the great importance that Malta must be involved wholeheartedly in surveys and any data collection studies that EFSA may request. The objective of this study was to establish the sensitivity pattern of the two mam antibiotics used for first line treatment which are mainly erythromycin and ciprofloxacin.

Due to the level of ciprofloxacin resistance noted in this study, erythromycin remains the drug of choice in the suspicion of any Campylobacter infection. Erythromycin is still mainly sensitive when compared to tetracycline, gentamicin and ciprofloxacin. Although, erythromycin is still the ideal drug to use, one must keep in mind that Campylobacter infections are generally self-limiting, and so over-use of this antibiotic is discouraged in order to retain this sensitivity in erythromycin.