Editor,
Thermophilic campylobacters, particularly Campylobacter jejuni, continue to remain the most common cause of acute bacterial enteritis in Northern Ireland. Most recent confirmed data for 2006 recorded 937 laboratory reports for Northern Ireland (http://www.cdscni.org.uk/surveillance/Gastro/Campylobacter_sp.htm), approximating to 53.8 cases per 100,000 individuals, compared to an attack rate of 86.7 and 42.8 cases per 100,000 individuals for England & Wales and the Republic of Ireland, respectively. However, in a previous epidemiological study1, it was estimated that the true prevalence of this infection was approximately 10.3-fold higher, due to patient under-reporting.
In relation to antibiotic resistance of local campylobacters, we have continued to map resistance trends2,3 during the perod 2004-2007 (n=1102) (Table I). The worrying finding of this study has been the marked increase in resistance to ciprofloxacin, rising to 31.7% in 2007, which is the highest level of resistance of these organisms to this agent that has ever been reported in Northern Ireland. Susceptibility data relating to ciprofloxacin resistance in local human clinical isolates were first reported in 1996 (9%) and this resistance rate has since risen steadily. Presently, the reason(s) for this increase in resistance is unclear. The most likely explanation for this is the ingestion of campylobacters which are more resistant to this agent, rather than the acquisition of resistance de novo in the human gastrointestinal tract, epecially as these organisms do not form part of the ecological microflora of the human gut. This therefore encourages examination of reservoirs and sources where such resistant organisms may enter the food chain. One possibility may be consumption of imported poultry meat from origins outside the EU, where veterinary controls of the use antibiotics in animal husbandry may not be stringent, thus leading to the development of fluoroquinolone resistant isolates in chickens prior to slaughter. A previous report in 20034 described the importation to Northern Ireland of 500 tonnes of chicken meat per week, which had a resistance to ciprofloxacin of 14% of isolates tested. Similar studies from Belgium5 and Spain have suggested ciprofloxacin resistance in poultry to be 42% and 99%, respectively.
Table I.
Percentage of wildtype Campylobacter isolates resistant to three antibiotic agents over the period 2004-2007.
| Year | ||||
|---|---|---|---|---|
| Antibiotic | 2004 (n=237) | 2005 (n=297) | 2006 (n=309) | 2007 (n=259) |
| Ciprofloxacin | 20.3% | 18.9% | 23.6% | 31.7% |
| Erythromycin | 2.5% | 3.4% | 1.9% | 1.2% |
| Tetracycline | 20.2% | 19.5% | 19.7% | 22.8% |
Another explanation for this rise in ciprofloxacin resistance in local human infections may be the acquisition of more resistant strains outside of Northern Ireland, particularly relating to travel abroad. The arrival of several budget and low cost airlines to Northern Ireland has lead to a marked increase in Northern Ireland residents travelling to countries which have a higher endemic rate of fluoroquinolone-resistance in campylobacters originating from animals, as well as humans. In 2007, airport passenger traffic to EU destinations increased by 21% at Belfast International Airport, resulting in 1,490, 775 passenger journeys (http://www.caa.co.uk/docs/80/airport_data/2007Annual/Table_10_1_EU_and_Other_Intl_Pax_Traffic_2007.pdf). Urgent attention now needs to be directed at this resistance issue in order to ascertain the origins of this marked rise in ciprofloxacin-reisitance in local campylobacters.
In conclusion, primary care practitioners, specialists in infectious diseases, microbiologists and epidemiologists need to be aware of the local increase in antibiotic resistance of thermophilic campylobacters to ciprofloxacin (31.2%) and the relative susceptibility of local wildtype isolates to erythromycin (1.2%).
Acknowledgments
This study was funded by the Research & Development Office, Department of Health & Public Safety, Northern Ireland [Infectious Disease—Recognised Research Group (RRG) 9.9].
The authors have no conflict of interest.
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