Survival of Campylobacter jejuni Co-Cultured with Salmonella spp. in Aerobic Conditions

Abstract

Campylobacter and Salmonella are responsible for the two major foodborne zoonotic diseases in Europe; poultry is the main infection source. Campylobacter cannot grow under aerobic conditions, but can show aerobic survival when co-cultured with other microorganisms; however, its interaction with Salmonella has not been studied yet. In this study, these two bacteria were co-cultured under controlled aerobic conditions. Different concentrations and strains of C. jejuni were incubated with or without different Salmonella serotypes (10 CFU) at 37 °C for 16 h. C. jejuni did not grow after incubation with or without Salmonella. The survival of C. jejuni was observed only for the highest initial concentration of 6 log CFU/mL with or without Salmonella. However, its survival was significantly higher when co-cultured with Salmonella. No survival was observed at lower concentrations. C. jejuni survival was positively affected by the presence of Salmonella but depended on the Salmonella serotype, the C. jejuni strain and the initial concentration. On the other hand, the Salmonella enumerations were not affected by C. jejuni. Our results suggest potential interactions between Salmonella and C. jejuni that require further investigations for a clearer understanding of their behavior in natural habitats.

Keywords: Campylobacter jejuni; Salmonella; co-culture; poultry production; survival.

Figure 1

C. jejuni C97Anses640 counts before and after incubation under aerobic conditions (with or without Salmonella Blegdam) (n = 10: (a–c) from 6 to 4 log CFU/mL, n = 4: (d,e) for 3 and 2 log CFU/mL). C bf inc: Initial concentration of C97Anses640 before incubation; C + S bf inc: Initial concentration of C97Anses640 co-cultured with S. Blegdam before incubation; C af inc: Final concentration of C97Anses640 after aerobic incubation; C + S af inc: Final concentration of C97Anses640 co-cultured with S. Blegdam after aerobic incubation.

Figure 2

C. jejuni C97Anses640 counts before and after incubation under aerobic conditions. (a) With or without Salmonella Typhimurium; (b) With or without Salmonella Enteritidis (n = 1).

Figure 3

C. jejuni strain counts before and after incubation of 4 log CFU/mL under aerobic conditions with or without different Salmonella serovars (light blue bars: initial concentration of C. jejuni; light gray bars: initial concentration of C. jejuni co-cultured with Salmonella; dark blue bars: final concentration of C. jejuni following aerobic incubation; dark gray bars: final concentration of C. jejuni co-cultured with Salmonella following aerobic incubation). (a) Six strains of C. jejuni were co-cultured with or without S. Blegdam 421, S. Typhimurium (S17 LNR1383) and S. Enteritidis (S17 LNR01420); (b) C. jejuni strains AC 302 and AC 541 co-cultured with or without S. Typhimurium (S20 LNR0260) and S. Enteritidis (S20 LNR0176) compared to S. Typhimurium (S17 LNR1383) and S. Enteritidis (S17 LNR01420).

Figure 4

Experimental protocol for survival assays: A culture of C. jejuni (from 8 to 4 log CFU/mL) was diluted to inoculate the bags, containing 250 mL buffered peptone water, with different final concentrations of C. jejuni ranging from 6 to 2 log CFU/mL. Then, C. jejuni obtained in the bags were cultured under aerobic conditions at 37 °C for 16 h in the presence or absence of 10 CFU of Salmonella spp.