A comparison of methods for the isolation of Campylobacter species from stool specimens

Eight methods used for isolation of Campylobacter species were compared. Using a combination of methods Campylobacter species were isolated from 30 (11%) of 270 children with diarrhea seen at Bamrasnaradura Infectious Disease Hospital, Nonthaburi, Thailand. The membrane filter method using a gas generating envelope at 37 degrees C identified 73% of the total positive specimens and was found to be the best isolation method for Campylobacter species from stool specimens. This method identified two strains that failed to grow on antibiotic containing media, and also gave a higher isolation rate of C. jejuni than could be isolated with conventional methods. The combination of the membrane filter method and a selective antibiotic method identified 90% of all isolates. At present the cost of the membrane filter method is higher than other methods. Therefore, the selective antibiotic method (Campy-BAP) with sheep blood under gas mixture at 42 degrees C is recommended for laboratories with limited supplies. Diagnosis by direct smear with 1% basic fuchsin revealed high degree of sensitivity and specificity. This rapid, inexpensive, and simple method could be used to make a presumptive diagnosis of Campylobacter enteritis when isolation methods are unavailable.