Effect of Temperature and Contact Time on Campylobacter jejuni Attachment to, and Probability of Detachment from, Stainless Steel

Abstract

The effect of temperature and contact time on attachment of six Campylobacter jejuni strains to, and probability of their detachment from, stainless steel were determined. Triplicate stainless steel coupons (SSC) were exposed to C. jejuni cell suspensions at 4, 25, 37, and 55°C for 30 min. An increase in temperature enhanced the numbers of cells of all strains of C. jejuni attaching to stainless steel from ~4 log/cm2 at 4°C to ~5 log/cm2 at 55°C. Cells attached to SSC at 4 and 25°C for 30 min were detached by the successive blotting technique on a series of Campylobacter blood-free selective agar plates. The probability of detachment was significantly (P < 0.05) higher at 4°C (≥0.219) than at 25°C (≥0.111) for five of the six strains tested, suggesting the strength of attachment was weaker at 4°C than at 25°C for these strains. C. jejuni cells were allowed to attach to SSC at 4°C for 1, 15, 30, 45, 60, 120, 180, 240, and 300 min. The numbers of cells attaching to SSC reached ~4 log/cm2 after 1 min of contact and increased slowly thereafter to ~5 log/cm2 after 300 min of contact. The probability of detachment significantly (P < 0.05) decreased from 0.443 after 1 min to 0.134 after 240 min of contact, indicating bacterial attachment was strengthened over time. These data suggest that to reduce the numbers of adhered cells on processing surfaces, low-temperature and early bacterial detachment procedures should be applied.