Suitability of repetitive-DNA-sequence-based PCR fingerprinting for characterizing epidemic isolates of Salmonella enterica serovar Saintpaul

Abstract

Three molecular typing methods, repetitive-sequence-based PCR (rep-PCR) fingerprinting, plasmid profiling, and arbitrarily primed PCR fingerprinting, were used to characterize isolates of Salmonella enterica serovar Saintpaul. Most of the isolates were obtained from epidemic human cases of food-borne salmonellosis, together with some from the food material suspected to be the source of infection, and a few were obtained from other cases apparently not related to the epidemic. All three methods adequately discriminated the epidemic strain from other strains of the serovar. In addition several isolates from human cases which are not identical to the epidemic strain were found. These isolates therefore must have been responsible for some sporadic infections, which were only temporally related to the epidemic. These strains showed a high degree of similarity to a strain isolated from a turkey. rep-PCR fingerprinting with REP-Dt primers and primer ERIC1R, applicable even to crude cell lysates, offers an attractive choice as a primary method for the discrimination of various Salmonella serotypes as well as isolates within serotype Saintpaul.

FIG. 1

Rep-PCR fingerprint patterns of S. saintpaul obtained with the REP-Dt primer pair. Lanes (isolate, source, date of isolation): 1, XL4427, potato chips, July 1993; 2, GGD930D, poultry, November 1995; 3, 026625, human feces, July 1993; 4, 019171, human feces, June 1993; 5, 041120, human feces, September 1993; 6, 211054, human feces, March 1993; 7, 143095, human feces, December 1995; 8, laboratory strain (date unknown); 9, negative control; 10, 100-bp marker.

FIG. 2

Rep-PCR fingerprint patterns of S. saintpaul with the ERIC1R primer. Lane assignments are the same as in Fig. 1.

FIG. 3

Dendrogram of the summarized fingerprint patterns obtained with primers REP-Dt and ERIC1R.

FIG. 4

AP-PCR fingerprint patterns of S. saintpaul obtained with the AP21 primer. Lanes (isolate, source, date of isolation): 1, XL4427, potato chips, July 1993; 2, GGD930D, poultry, November 1995; 3, 026625, human feces, July 1993; 4, 019171, human feces, June 1993; 5, 041120, human feces, September 1993; 6, 211054, human feces, March 1993; 7, 143095, human feces, December 1995; 8, 41, laboratory strain (date unknown); 9, 206917, human feces, March 1996; 10, negative control; M, 100-bp marker.

FIG. 5

AP-PCR fingerprint patterns of S. saintpaul obtained with the AP22 primer. Lane assignments are the same as in Fig. 4.