This article brings down to the poultry matrix what is explained in Salmonella: characteristics, detection and control and complements microbiology in the meat industry.
Table of contents
A raw product that depends on the rest of the chain
Chicken meat leaves the plant as a raw product. There is no cooking step in the factory that eliminates Salmonella: what reaches the consumer is what slaughter, chilling and the cold chain managed to control, and the rest is done by cooking and hygiene in the kitchen. That is why regulators measure contamination in the plant itself and not only in the final product.
It is worth sizing the problem without exaggerating it. In the European Union there were 79,703 confirmed cases of salmonellosis in 2024, a rate of 18.6 per 100,000 inhabitants, according to the EFSA and ECDC One Health report. In that same report, the agent-food pair of greatest concern in outbreaks was Salmonella in eggs and egg products, not in poultry meat. Among fresh meats, however, chicken had the most positive samples: 4.9% of 95,954 units analyzed, compared with 4.7% in turkey, 1.6% in pork and 0.57% in bovine. In the United States, FSIS cited IFSAC estimates according to which 18.6% of Salmonella illnesses were attributed to chicken products and 5.5% to turkey products, 24.1% in total. That is: one of the matrices most linked to salmonellosis, although not the only one. The fundamentals of the pathogen are in this article on Salmonella.
Where poultry meat becomes contaminated and spreads contamination during slaughter
Birds arrive with Salmonella on feathers, feet and in the intestine, often without signs of illness. From there, each stage can reduce the load or spread it among carcasses. A 2026 study at a large-scale plant in Paraná, Brazil, followed the same 15 carcasses per week for 20 weeks and sampled them at seven points on the line (2,100 analyses in total). Its results illustrate how the pathogen moves, although they come from a single plant and one dominant serovar (Heidelberg, 91.5% of isolates), so they should not be extrapolated as general figures.
Before scalding
This was the most contaminated point: 78.7% of carcasses positive, with a mean count of 1.30 log MPN/g. It reflects what the live bird brings in feathers and fecal matter.
Scalding
With the water at about 60 °C on average, counts dropped by 0.81 log MPN/g and the proportion of positives fell to 42.7%. The authors point out that scalding water can also become a source of contamination because of the organic matter it accumulates.
Defeathering
Between scalding and defeathering the mean count rose by 0.11 log MPN/g. Poorly sanitized defeathering equipment is one of the stages most cited in the literature as spreading Salmonella among carcasses.
Evisceration
Rupture of viscera is a direct fecal contamination risk. In the plant studied, the critical control point after evisceration, where carcasses with visible contamination are removed, and the final wash before chilling were associated with significant reductions (the final wash, 0.12 log MPN/g).
Chilling
After immersion chilling, 36.7% of carcasses were still positive. Between the entry and the exit of the line the average dropped by 0.97 log (from 1.30 to 0.33 log MPN/g): the process reduces the load, it does not eliminate the hazard. In addition, pulsed-field gel electrophoresis analysis showed that the Heidelberg isolates had 90% similarity among themselves, with very similar profiles at different stages and weeks, an indication that related strains circulate along the line and recur over time.
European Union criteria: two regulations, two different questions
Regulation (EC) 2160/2003: controlling at the source
This regulation seeks to detect and control Salmonella and other zoonotic agents at all relevant stages, with a focus on primary production. It sets prevalence reduction targets in animal populations and requires national control programs. For poultry, the targets are expressed on the serovars of greatest public health importance: S. Enteritidis and S. Typhimurium (including its monophasic variant) in meat production, and in addition Infantis, Hadar and Virchow in Gallus gallus breeding flocks. In 2024, the prevalence of broiler flocks positive for the target serovars was 0.29% in the EU, compared with a target of 1% or less, according to EFSA and ECDC.
Regulation (EC) 2073/2005: food safety criterion and process hygiene criterion
This regulation establishes two instruments with different logics. It is important not to confuse them:
- Food safety criterion (row 1.28, fresh poultry meat). Absence of S. Typhimurium (including the monophasic 1,4,[5],12:i:-) and S. Enteritidis in 25 g, with n = 5 and c = 0, evaluated throughout the shelf life of the product. It applies to fresh meat from Gallus gallus breeders and layers, broilers and breeding and fattening turkeys. The reference method is EN ISO 6579-1 for detection and the White-Kauffmann-Le Minor scheme for serotyping.
- Process hygiene criterion (row 2.1.5, chicken and turkey carcasses). Salmonella spp. (any serovar) in 25 g of a pooled neck skin sample, after chilling, with n = 50. c = 7 was allowed, reduced to c = 5 since 2012 for broilers and since 2013 for turkeys, that is, up to 5 of 50 samples (10%) positive. It is an indicator of whether the process works under control, not a criterion for accepting a batch. If it is not met, the regulation calls for improving slaughter hygiene and reviewing process controls, the origin of the animals and farm biosecurity.
The difference matters. The safety criterion looks at the product and only two serovars; the hygiene one looks at the process and all Salmonella. A 2026 study on this gap points out that serovars not listed as relevant have no harmonized treatment in fresh meat, a gap that becomes more delicate with S. Infantis, an emerging and multidrug-resistant serovar. In nine poultry plants in northeastern Italy (2021-2023), S. Infantis accounted for 61.7% of isolates, and six of the nine had recurring non-compliances with the hygiene criterion, between 17% and 82% of operating time.
Another surprising fact: in 2024, among chicken carcasses sampled by the competent authorities, 18.7% tested positive for Salmonella, compared with 4.9% in the companies' own controls. In the nine Italian plants mentioned, the authors observed a similar gap (30.7% versus 8.7% of positives for Salmonella) and attribute it mainly to the different sampling frequency. That is why each plant should look at its own trends and not only at a one-off compliance.
Not only fresh meat: processed poultry products
EU data for 2024 show that contamination is not limited to fresh product. Among the samples reported under Regulation 2073/2005, the percentages positive for Salmonella were 7.7% in fresh poultry meat at distribution (6.3% at manufacture), 13.2% in poultry meat products intended to be eaten cooked at manufacture (5.0% at distribution), 12.8% in mechanically separated meat at manufacture (3.6% at distribution) and 9.9% in minced meat and poultry preparations intended to be eaten cooked at manufacture (5.8% at distribution). In ready-to-eat products positivity was low overall (0.23%), with 1.3% in chicken meat and products. For the control of these products the same logic applies: what comes in raw and contaminated is redistributed when it is minced or separated, as explained in microbiology in the meat industry.
United States: USDA-FSIS performance standards
The U.S. approach is different. FSIS verifies each establishment with performance standards expressed as the maximum number of positives allowed out of a target number of samples, over a moving 52-week window:
- Broiler chicken carcasses: 5 of 51 (9.8%).
- Young turkey carcasses: 4 of 56 (7.1%).
- Chicken parts: 8 of 52 (15.4%).
- Ground or mechanically deboned chicken: 13 of 52 (25.0%).
- Ground turkey: 7 of 52 (13.5%).
Establishments are classified into three categories according to their performance. Category 1 corresponds to those at 50% or less of the maximum allowed, category 2 to those that comply but exceed that 50%, and category 3 to those that exceed the maximum. FSIS clarifies that it does not issue a notice of intended enforcement action or suspend inspection solely because an establishment fails to meet a standard.
In August 2024 FSIS proposed a different framework: declaring raw chicken adulterated if it has Salmonella at 10 CFU/mL (or per gram) of rinse or more together with the presence of certain serovars (Enteritidis, Typhimurium and I 4,[5],12:i:-). The proposal was withdrawn on April 25, 2025, after receiving 7,089 comments, and the agency said it would reassess its approach. That is why, when drafting a verification program, it is advisable to look at the rule in force and not at the withdrawn proposal.
How the sample is taken
Sampling changes what the result means. For the European hygiene criterion, the regulation asks to sample whole carcasses with neck skin after chilling:
- Selection. At random, a minimum of 15 carcasses per session if Salmonella and Campylobacter are analyzed in the same laboratory, or 20 if they are analyzed in different laboratories.
- Pooling. The neck skin of at least 3 carcasses (or 4, in the second case) from the same flock is pooled into a composite sample of 26 g (or 35 g), until five final samples are formed. The 35 g sample is divided into 25 g for Salmonella and 10 g for Campylobacter, the hygiene criterion that is evaluated on the same carcasses (see Campylobacter).
- Transport. Between 1 °C and 8 °C. The general principles of sample preservation are in sample transport and preservation.
- Priority. Carcasses from flocks with unknown status or positive for S. Enteritidis or S. Typhimurium must be included in the sampling plans.
In the United States, FSIS works with rinses of carcasses and chicken parts and with samples of ground product; in its 2024 proposal the levels were expressed per milliliter of rinse or per gram. Because the European and U.S. regulations measure differently, percentages of positives cannot be compared directly between the two. To understand how n, c, m and M are interpreted in a criterion, see attribute sampling plans.
How it is detected: ISO 6579-1 and alternative methods
The reference method
EN ISO 6579-1 is the method named in rows 1.28 and 2.1.5 of the regulation. It is a culture method: pre-enrichment in buffered peptone water, selective enrichment, isolation on solid media and biochemical and serological confirmation. The Brazilian study cited applied it with 18 h incubation in peptone water, two selective broths (Müller-Kauffmann tetrathionate with novobiocin and Rappaport-Vassiliadis), XLD agar and bismuth sulfite agar, and confirmation of typical colonies. Reaching a confirmed result takes several days, as described in traditional microbiological culture and enrichment.
What the European regulation allows instead of culture
Article 5 of Regulation 2073/2005 admits alternative analytical methods if they are validated against the reference method according to the EN ISO 16140-2 protocol, for the food category of the criterion or for a broad range of foods. Proprietary methods, in addition, must be certified by an independent body. Validation is what allows a rapid method to be equated with the reference one. What is evaluated in that series of standards is explained in validation and verification of microbiological methods.
Where PCR fits in
Real-time PCR is generally applied on the already enriched broth and answers whether there is Salmonella in the portion analyzed. It is useful for deciding quickly which batches or carcasses continue in the confirmation chain. Two practical warnings:
- A PCR positive is presumptive until confirmed (see presumptive vs. confirmed result).
- Genus-level PCR responds well to the process hygiene criterion, which counts Salmonella spp. For row 1.28, which depends on the serovar, an isolate for serotyping is also needed. Keeping it during the analysis also allows genetic relatedness studies, such as those of genomic sequencing.
The role of environmental monitoring in a poultry plant
Article 5 of the European regulation indicates that samples be taken from processing areas and equipment when necessary to ensure compliance with the criteria, with ISO 18593 as the reference method. In a slaughter plant this covers contact surfaces such as defeathering equipment, evisceration and chilling tanks, and also indirect zones such as drains and floors, as developed in environmental monitoring in food plants and Enterobacteriaceae and Salmonella on post-sanitation surfaces.
Cleaning reduces the load, but does not eliminate it. A 2025 study at two broiler plants measured that cleaning and disinfection lowered surface counts from 3.7 to 1.8 log CFU/cm² in one plant and from 7.0 to 3.8 in the other. With disinfectants at the recommended concentration, between 7% and 53% of bacteria in laboratory biofilms survived depending on the product. That work did not focus on Salmonella (it isolated Listeria monocytogenes, E. coli and Yersinia enterocolitica, among others), but it shows why a visually clean surface can still be a reservoir. The mechanism is in biofilms in food plants.
Which TAAG kits relate to this matrix
In the TAAG catalog there are two Salmonella spp. kits with declared scope in the meat and poultry sector. Ampliora 1.1 Salmonella spp. (V-SF97, real-time PCR with Mila) declares raw chicken and surfaces as matrices. Specio 1.1 Salmonella spp. (V-SF31, real-time PCR with melting curve) declares food, beverages and living and inert surfaces, and includes the meat and poultry industry. Both detect Salmonella at genus level, not serovar. If the sample type is neck skin, carcass rinse or a processed product, the scope must be confirmed with TAAG before using it as an alternative to ISO 6579-1. To choose the kit by industry and matrix, see how to choose a TAAG kit.
Conclusion
Chicken meat leaves the plant raw, and a good part of the risk is decided at slaughter: scalding and washing reduce the load, defeathering and chilling can spread it, and no stage eliminates it completely. The regulatory frameworks measure different things: the EU separates a safety criterion by serovar from a process hygiene criterion by genus, and USDA-FSIS verifies the performance of each establishment with percentage-of-positives standards. Choosing the sampling well, understanding what the method answers (culture, presumptive PCR, confirmation and serotyping) and sustaining an environmental monitoring program that includes biofilms is what makes an analytical result truly useful.
About TAAG
Consult TAAG on the scope of Ampliora 1.1 Salmonella spp. and Specio 1.1 Salmonella spp. for your poultry matrix and your verification scheme.
Frequently asked questions
Is chicken meat the main cause of salmonellosis?
It is one of the most linked matrices, but not the only one. In the EU, EFSA and ECDC identified in 2024 eggs and egg products as the agent-food pair of greatest concern in outbreaks, and in the U.S. the attribution estimates cited by FSIS assign about 18.6% of Salmonella illnesses to chicken and 5.5% to turkey.
What is the difference between the safety criterion and the process hygiene criterion in Regulation 2073/2005?
The safety one (row 1.28) requires absence of S. Typhimurium and S. Enteritidis in 25 g of fresh poultry meat throughout the shelf life; if it fails, the batch is not compliant. The hygiene one (row 2.1.5) counts Salmonella spp. of any serovar on neck skin of chilled carcasses (up to 5 positives of 50) and evaluates whether the process is under control, without serving by itself to accept or reject a batch.
Why is neck skin sampled and not the meat?
The European regulation defines the neck skin of chilled carcasses as the sample for the process hygiene criterion. It is the reference zone for comparing plants and controlling slaughter hygiene; row 1.28 is evaluated on fresh meat on the market.
Is a positive PCR enough to reject a batch of chicken?
Not by itself. The positive is presumptive until confirmed, and for the European safety criterion the serovar must also be identified from an isolate. PCR is useful for quickly deciding which samples go on to confirmation.
Can PCR be used instead of ISO 6579-1 to demonstrate compliance?
In the EU, Article 5 of Regulation 2073/2005 allows it if the method is validated against the reference according to EN ISO 16140-2 for the food category and, if proprietary, certified by an independent body. Outside the EU, the requirements of each authority apply.