Different Contamination Patterns of Lineage I and II Strains of Listeria monocytogenes in a Spanish Broiler Abattoir

Abstract

The purpose of this study was to determine whether genetically similar or diverse strains of Listeria monocytogenes colonize the environment and carcasses in a single Spanish broiler abattoir over time. The study was composed of 5 surveys over a 1.5-yr period and included the monitoring of cleaning and disinfection procedures. Overall, a total of 212 samples were tested for the presence of L. monocytogenes, and 31% of the samples were found to be positive. Listeria monocytogenes was isolated from carcasses and product contact and noncontact sites in the evisceration and carcass classification areas of the abattoir. A total of 132 L. monocytogenes isolates were characterized by PCR-based serotyping and pulsed-field gel electrophoresis (PFGE) restriction analysis with the endonucleases ApaI and AscI. Molecular serotyping showed that L. monocytogenes isolates were of serotypes 1/2a and 1/2b. Isolates of serotype 1/2b (89.4%) were contaminating carcasses as well as environmental product contact and noncontact sites, whereas isolates of serotype 1/2a (10.6%) were recovered only from environmental product noncontact sites. A relatively low genetic diversity was found in this group of L. monocytogenes isolates from the abbatoir; only 14 different PFGE types (A1 to A14) were obtained. Nine pulsotypes belonging to serotype 1/2b (lineage I) were grouped in only one PFGE genetic cluster, whereas 5 pulsotypes belonging to serotype 1/2a (lineage II) were grouped into 4 PFGE genetic clusters. Two genetically related pulsotypes of serotype 1/2b (A1 and A2, 64.4% of the isolates) predominated and persisted in the abattoir. Our study indicated that a few strains of L. monocytogenes lineage I that were genetically very closely related might be specifically adapted to colonizing the evisceration zone of the abattoir and were predominant on carcasses over 1 yr. On the other hand, a genetically diverse group of lineage II strains were present in the abattoir environment, but never contaminated carcasses.

Diverse Geno- and Phenotypes of Persistent Listeria monocytogenes Isolates from Fermented Meat Sausage Production Facilities in Portugal

“…Persistence may indicate deficiencies in sanitation procedures or potential niches in the processing environment where L. monocytogenes is protected from sanitation. While persistence of L. monocytogenes in meat processing plants (15,37,38,61) and in other plants (44,47,73) has previously been reported, identification of different PFGE types (as well as different molecular serotypes and lineages) associated with persistence in different plants (except for one PFGE type associated with persistence in two plants) clearly suggests that many different L. monocytogenes strains have the ability to establish persistent populations in processing plants.…”

“…While L. monocytogenes persistence in food processing plants and other food-associated environments has been well documented (30,33,37,38,44,47), it still remains largely unclear whether persistent strains share unique genetic or phenotypic characteristics or whether establishment of persistence is largely a random process with most L. monocytogenes strains being able to establish persistence if they are introduced into an appropriate location at an opportune time. While some authors have reported that isolates representing persistent subtypes appear to possess specific characteristics that facilitate persistence, such as resistance to disinfectants (1,39), improved ability to adhere to food contact surfaces and to form biofilms (6,40), others have found no evidence that persistent strains adhere better to surfaces (28) or are more resistant to disinfectants (14,31).…”

“…Despite the implementation of intensive control measures, eradication and control of L. monocytogenes in food processing environments remain considerable challenges. Several studies indicate that the most important source of food contamination with L. monocytogenes is via cross-contamination from the equipment and general environment of the processing plants, where some L. monocytogenes strains can persist over extended periods, while others are recovered only sporadically (30,33,37,38,44,47). While several authors attempted to identify specific characteristics, e.g., biofilm formation or sanitizer resistance capabilities, that may be associated with L. monocytogenes persistence in processing plants (1,6,39,49), little attention has been given to the potential contributions of prophages to the ability of L. monocytogenes to establish persistence.…”

Total and Thermo-Tolerant Coliforms<i>,</i><i> </i><i>Salmonella</i><i> </i><i>spp.,</i><i> </i><i>Escherichia</i><i> </i><i>coli,</i><i> </i><i>Pseudomonas</i><i> </i><i>spp</i><i> </i>and <i>Listeria</i><i> </i><i>monocytogenes</i><i> </i>in Broilers Chicken Meat Processing Chain in Southern

“…In Spain, López et al [6] detected a 31% occurrence of L. monocytogenes in chicken carcasses during the processing stages.…”

“…The contamination level by degrading and pathogenic indicator microorganisms, such as Salmonella spp. and Listeria monocytogenes is still a fact that should be set right in broiler abattoirs and in selling outlets where these products and their derivatives are commercialized [6,7,8].…”