Staphylococcus aureus Isolated From Traditional Artisanal Raw Milk Cheese from Southern Brazil: Diversity, Virulence, and Antimicrobial Resistance Profile.

Staphylococcus aureus is one of the primary pathogenic agents found in cheeses produced with raw milk. Some strains of S. aureus are enterotoxigenic, possessing the ability to produce toxins responsible for staphylococcal food poisoning when present in contaminated foods. This study aimed to genotypically characterize, assess the antimicrobial resistance profile, and examine the enterotoxigenic potential of strains of S. aureus isolated from artisanal colonial cheese. Additionally, a bacterial diversity assessment in the cheeses was conducted by sequencing the 16S rRNA gene. The metataxomic profile revealed the presence of 68 distinct species in the cheese samples. Fifty-seven isolates of S. aureus were identified, with highlighted resistance to penicillin in 33% of the isolates, followed by clindamycin (28%), erythromycin (26%), and tetracycline (23%). The evaluated strains also exhibited inducible resistance to clindamycin, with nine isolates considered multidrug-resistant (MDR). The agr type I was the most prevalent (62%) among the isolates, followed by agr type II (24%). Additionally, ten spa types were identified. Although no enterotoxins and their associated genes were detected in the samples and isolates, respectively, the Panton-Valentine leukocidin gene (lukS-lukF) was found in 39% of the isolates. The presence of MDR pathogens in the artisanal raw milk cheese production chain underscores the need for quality management to prevent the contamination and dissemination of S. aureus strains.

Raw milk cheeses from Beira Baixa, Portugal-A contributive study for the microbiological hygiene and safety assessment.

Due to specific bacterial microbiota, raw milk cheeses have appreciated sensory properties. However, they may pose a threat to consumer safety due to potential pathogens presence. This study evaluated the microbiological contamination of 98 raw milk cheeses from Beira Baixa, Portugal. Presence and enumeration of Coagulase Positive Staphylococci (CPS), Listeria monocytogenes, Salmonella spp., pathogenic Escherichia coli, and indicator microorganisms (non-pathogenic E. coli and Listeria spp.) was attained. E. coli antimicrobial resistance (AMR) was also evaluated. PCR and/or Whole genome sequencing (WGS) was used to characterize E. coli, Salmonella spp. and L. monocytogenes isolates. Sixteen cheeses (16.3%) were classified as Satisfactory, 59 (60.2%) as Borderline and 23 (23.5%) as Unsatisfactory/Potential Injurious to Health. L. monocytogenes, CPS > 104 cfu g-1, Extraintestinal pathogenic E. coli (ExPEC) and Salmonella spp. were detected in 4.1%, 6.1%, 3.1% and 1.0% of the samples, respectively. Listeria innocua (4.1%) and E. coli > 104 cfu g-1 (16.3%) were also detected. AMR E. coli was detected in 23/98 (23.5%) of the cheese samples, of which two were multidrug resistant. WGS identified genotypes already associated to human disease and Listeria spp. cluster analysis indicated that cheese contamination might be related with noncompliance with Good Hygiene Practices during cheese production.

Evaluation of Extraction Methods to Detect Noroviruses in Ready-to-Eat Raw Milk Minas Artisanal Cheese.

This study aimed to assess two homogenization methods to recover norovirus from Minas artisanal cheese (MAC) made with raw bovine milk obtained from four microregions of the Minas Gerais state, Brazil, with different ripening times and geographical and abiotic characteristics. For this purpose, 33 fiscal samples were artificially contaminated with norovirus GI and GII, and Mengovirus (MgV), used as an internal process control (IPC). TRIzol® reagent and Proteinase K homogenization methods were evaluated for all samples were then subjected to RNA extraction using viral magnetic beads and RT-qPCR Taqman® for viral detection/quantification. Proteinase K method showed better efficiency results for both norovirus GI and GII, with means recovery efficiency of 45.7% (95% CI 34.3-57.2%) and 41.4% (95% CI 29.1-53.6%), respectively, when compared to TRIzol method (16.6% GI, 95% CI 8.4-24.9%, and 12.3% GII, 95% CI 7.0-17.6%). The limits of detection for norovirus GI and GII for this method were 101GC/g and 103GC/g, respectively, independent of cheese origin. MgV was detected and revealed in 100% success rate in all types of cheese, with mean recovery efficiency of 25.6% for Proteinase K, and 3.8% for the TRIzol method. According to cheese origin, Triangulo Mineiro MAC had the highest mean recovery rates for the three viral targets surveyed (89% GI, 87% GII, and 51% MgV), while Serro MAC showed the lowest rates (p < 0.001). Those results indicate that the proteinase K adapted method is suitable for norovirus GI and GII detection in MAC and corroborated MgV as an applicable IPC to be used during the process.

Profile of lactic acid bacteria (MALDI-TOF-MS) and physico-chemical and microbiological characteristics of the raw milk and fresh artisanal cheese from Serra Geral, Minas Gerais, Brazil.

Artisanal cheese from Serra Geral, Minas Gerais, Brazil, stands out for its cultural asset and socio-economic relevance. However, standards of identity and quality and the peculiar terroir associated with the edaphoclimatic conditions have not been established. Therefore, the production flow diagram and the physico-chemical and microbiological quality of the raw milk, pingo (natural starter culture), production benches, water and fresh cheese were investigated for the first time. In addition, lactic acid bacteria (LAB) from cheese and its production environment were identified by MALDI-TOF. For that, 12 cheese making facilities were selected. The raw milk and pingo showed adequate physico-chemical characteristics for cheesemaking; however, high microbial counts were found. In the water, total and thermotolerant coliforms were also identified. The fresh cheeses were classified as 'high moisture and fat' and 'soft mass'. Most physico-chemical parameters were satisfactory; however, there were high counts of total coliforms, Staphylococcus spp. and coagulase-positive staphylococci. There were high counts of LAB in the raw milk, pingo, bench surface and fresh cheese. A total of 84 microbial biotypes from MRS agar were isolated. Lactococcus lactis was the predominant LAB, followed by Lactococcus garvieae. Leuconostoc mesenteroides (benches), Leuconostoc pseudomesenteroides (fresh cheese), and Enterococcus faecium (pingo) were identified sporadically. These results indicate the risks to public health associated with the consumption of the fresh cheese, and measures to improve its safety are needed.

Brazilian artisanal Colonial cheese: characterization, microbiological safety, and survival of Salmonella enterica serovar Enteritidis during ripening.

The artisanal Colonial cheese is typical of the southern region of Brazil and dates back to the colonization by Italian and German immigrants. Produced with raw milk, it is the main cheese produced by more than 15,200 small rural proprieties. The consumer increasingly appraises food with territorial valorization, demanding specific sanitary norms for this type of cheese. This work aimed to know the physical-chemical characteristics of the cheeses produced in the west of Santa Catarina State, to study the ripening time to reach microbiological safety, and to experimentally observe the survival of Salmonella enterica serovar Enteritidis ATCC 13076 during the ripening. The physical-chemical characterization was performed with 129 samples of cheeses. Five dairies were selected for evaluation of the ripening process. Salmonella survival using a challenge test was performed on three batches prepared in a pilot plant. The cheeses were classified as high (15.4%), medium (74.6%), and low moisture (9.2%), and concerning fat content as semi-fat (37.5%) and fat (62.5%). Salmonella challenge test demonstrated their survival for up to 28 days, depending on the initial contamination. The ripening monitoring showed that thermotolerant coliforms could be a good indicator of the process because they are the most persistent microorganisms.

In vitro evaluation of probiotic and technological properties of lactic acid bacteria isolated from artisanal cheese produced in the Serra Geral - Minas Gerais - Brazil / Avaliação in vitro de propriedades probióticas e tecnológicas de bactérias ácido-láticas isoladas de queijo artesanal da Serra Geral (MG)

O presente estudo avaliou o potencial probiótico in vitro de bactérias ácido-láticas (BAL) isoladas de queijo artesanal da Serra Geral (MG), com 14 e 21 dias de maturação, leite cru e pingo, utilizados em sua elaboração, e de bancadas de produção. As bactérias foram submetidas aos testes de antibiograma, à tolerância a ácido gástrico artificial e a sais biliares e ao antagonismo contra micro-organismos indicadores. Levilactobacillus brevis (Q521) e Lactococcus lactis (LLSG) apresentaram os melhores resultados e foram selecionados para a produção de leite fermentado. Apenas LLSG foi capaz de fermentar o leite. O produto apresentou qualidade microbiológica e físico-química adequada, exceto para os teores de proteína, segundo a legislação vigente para leites fermentados, demonstrando potencial tecnológico. A partir dos resultados apresentados, sugere-se que testes in vivo sejam realizados para que LLSG possa vir a ser utilizado como probiótico.

Antagonistic activity of lactic acid bacteria isolated from Minas artisanal cheeses against Brucella abortus / Atividade antagonista de bactérias lácticas isoladas de queijos Minas artesanais contra Brucella abortus

This study aimed to evaluate methods for studying the in vitro antimicrobial activity of lactic acid bacteria (LAB) against Brucella abortus and to evaluate the antagonistic effect of LAB on the viability of this pathogen. A total of 18 LAB strains (Lactobacillus plantarum, n = 11; Pediococcus acidilactici, n = 1; Lactobacillus rhamnosus, n = 4; and Lactobacillus brevis,n = 2), isolated from Minas artisanal cheeses produced in three regions (Canastra, Campos das Vertentes, and Araxá) of Minas Gerais State, Brazil, were tested for their antimicrobial activity against B. abortus using three methods: spot-on-lawn, agar well diffusion assay, and antagonistic activity of the culture supernatants. None of the tested LAB strains could inhibit B. abortus in the spot-on-lawn and agar-well diffusion assays. The supernatants produced by LAB had an acidic pH, with intensity depending on bacterial growth and strain, and could inhibit the growth of B. abortus. In contrast, pH-neutralized (pH 7.0) LAB supernatants did not suppress the growth of B. abortus. The results showed that the best technique to study the in vitro antagonism of LAB against B. abortus was the antagonistic activity of culture supernatants. The growth of B. abortus may have been inhibited by acid production.(AU)

Este estudo teve como objetivo avaliar métodos de estudo in vitro da atividade antimicrobiana de bactérias lácticas contra Brucella abortus e avaliar o efeito antagônico das mesmas sobre a viabilidade deste patógeno. Um total de 18 amostras de bactérias lácteas (Lactobacillus plantarum, n = 11; Pediococcus acidilactici, n = 1; Lactobacillus rhamnosus, n = 4; e Lactobacillus brevis, n = 2), isoladas de exemplares de Queijo Minas Artesanal produzidos em três regiões (Canastra, Campos das Vertentes e Araxá) do estado de Minas Gerais, Brasil, foram testados quanto à sua atividade antimicrobiana contra B. abortus usando três métodos: spot-on-lawn, ensaio de difusão em poço e atividade antagonista de sobrenadante de cultura. Nenhuma das cepas testadas foi capaz de inibir B. abortus nos ensaios spot-on-lawm e de difusão em poço. Os sobrenadantes produzidos pelas bactérias lácteas apresentaram pH ácido, com intensidade dependente do crescimento bacteriano e da amostra, podendo inibir o crescimento de B. abortus. Em contraste, os sobrenadantes com pH neutralizado (pH 7,0) não inibiram o crescimento de B. abortus. Os resultados mostraram que a melhor técnica para estudar o antagonismo in vitro de bactérias lácteas contra B. abortus foi a atividade antagonista de sobrenadante de cultura. O crescimento de B. abortus pode ter sido inibido pela produção de ácido.(AU)

Recovery of Brucella in raw milk Minas artisanal cheese approved for consumption by official inspection agency in Brazil: assessment of prevalence and risk factors through One Health integrated approaches.

BACKGROUND: Minas artisanal cheese (MAC) from the Serro region is a Brazilian intangible cultural heritage. Produced from raw milk, it may carry zoonotic pathogens such as Brucella. This study included a randomized survey for the prevalence of Brucella-positive MAC and its associated factors. METHODS: MAC samples (n=55), each one from a different rural family-based cheese-processing agroindustry, were analysed for Brucella by direct polymerase chain reaction (PCR) species-specific DNA detection and cultivation-based approaches. RESULTS: Among 55 MACs that were analysed, we found 17 Brucella DNA-positive samples (30.9% [95% confidence interval {CI} 18.7 to 43.1]) by PCR and, for the first time, from one MAC (1.8% [95% CI 0.5 to 9.7]), viable Brucella abortus was recovered by cultivation. Higher values for two variables, the number of lactating cows per herd (p=0.043) and daily milk production per herd (p=0.043), were each associated with Brucella-positive MAC, which concentrated in three high-risk and one low-risk spatial clusters. CONCLUSIONS: MAC may be a source of Brucella for humans, since the positive samples were from batches that were sold by cheesemakers. This should be of concern and encourage cooperation between the health and agriculture sectors in order to mitigate this public health risk through One Health integrated approaches.

Pequi (Caryocar brasiliense) Waste Extract as a Synergistic Agent in the Microbial and Physicochemical Preservation of Low-Sodium Raw Goat Cheese.

The growth of spoilage and pathogenic bacteria during storage represents significant losses in marketing raw milk cheeses. Thus, reducing NaCl in these products is challenging, as sodium has a critical antimicrobial role. Despite advances in non-thermal technologies, the short shelf life still limits the availability of raw goat cheese. Thus, combined preservation methods can be promising because their synergies can extend shelf life more effectively. In this context, Principal Component Analysis (PCA) was applied to variables to investigate the effect of pequi waste extract (PWE), a native Brazilian fruit, combined with UV-C radiation (CEU) and vacuum packaging (CEV) on the preservation of low-sodium raw goat cheese. CEV samples had lower loadings for Staphylococcus subsp. and Enterobacteriaceae than other treatments in PC2, having a count's reduction up to 3-fold (P < 0.05) compared to vacuum alone. In contrast, CEU showed an increase of up to 1.2-fold on staphylococcal count compared to UV-C alone. Still, the addition of PWE to UV-C-treated cheeses resulted in 8.5% protein loss. Furthermore, PWE, especially in CEV, delayed post-acidification during storage. It made CEV up to 4.5 and 1.6-fold more stable for color and texture, respectively than vacuum alone. These data strongly suggest that PWE may be a novel and promising synergistic agent in the microbial and physicochemical preservation of low-sodium raw milk cheese when combined with the vacuum.

Minas Artisanal Cheese As Potential Source of Multidrug-Resistant Escherichia coli.

Bacteria develop resistance to antibiotics naturally, but the inappropriate and widespread use of antibiotics in humans and animals has made antimicrobial resistance one of the biggest threats to modern medicine. Raw milk cheese can represent an important source of antimicrobial resistance. Thus, the objective of this study was to evaluate the prevalence and sensitivity of Escherichia coli isolated from artisanal cheese made from raw milk produced in Minas Gerais, Brazil. E. coli counts were determined using the most probable number method. An antibiogram was performed using the disk diffusion method, following the protocol described by the Brazilian Committee on Antimicrobial Susceptibility Testing (BrCAST) for 14 antibiotics of nine classes. E. coli was detected in 35 (71.4%) of the samples, with populations between 0.56 to 4.87 log (NMP/g) of cheese. The presence of E. coli resistant to multiple antimicrobials was more frequent in cheeses, with an E. coli population below the levels established by regulatory limits. Only four samples (11.4%) had all E. coli isolates susceptible to the 14 antimicrobials evaluated. The results showed the heterogeneity of antimicrobial resistance in E. coli between the producing regions of Minas artisanal cheese. Multidrug resistance was detected in 29% of the E. coli isolates and in almost 40% (38.8%) of the cheese samples. The frequency of multidrug-resistant (MDR) isolates was different between the production regions (p < 0.05). The presence of MDR E. coli in cheese from region D was 14, 4, and 20 times more likely than in cheese from regions A, B, and C, respectively. A multiple antibiotic resistance index of 0.200 predicted the presence of MDR E. coli in raw milk artisanal cheese with 99% probability. In conclusion, artisanal cheese can act as sources of MDR E. coli to colonize the human gastrointestinal tract.

Assessment of Viral Contamination of Five Brazilian Artisanal Cheese Produced from Raw Milk: a Randomized Survey.

Enteric viruses have been described as important contaminants in fresh and ready-to-eat foods such as sandwiches, deli meat and dairy products. This is a cross-sectional randomized survey to estimate the prevalence of norovirus and human adenovirus (HAdV) from 100 Brazilian artisanal raw milk cheese samples (Minas and Coalho) obtained from different agroindustries in four producing regions in the states of Minas Gerais and one in Piauí, respectively. From October 2017 to April 2018, norovirus genogroups I and II and HAdV were investigated in these cheese samples by RT-qPCR and qPCR, respectively. Viruses were detected in 43 samples, being 26 norovirus GI strains, 14 HAdV, and 3 both viruses. Norovirus GII strains were not detected. Viral concentrations ranged from 6.17 × 104 to 1.44 × 107 genome copies/L-1 and murine norovirus 1 used as internal process control showed 100% success rate of recovery with efficiency of 10%. There was a trend towards a higher positivity rate for both viruses in the rainy season, and HAdV were more commonly found among samples with higher fecal coliform counts. This study is a first step in assessing the risk that this contamination may pose to the consumer of raw products as well as emphasizing the need for good manufacturing practices, quality control systems in the dairy industry and markets. As a randomized survey, we established baseline figures for viruses' prevalence in five types of ready-to-eat raw milk artisanal Brazilian cheese, to allow any monitoring trends, setting control targets and future local risk analyses studies.

Brazilian Artisanal Cheeses: An Overview of their Characteristics, Main Types and Regulatory Aspects.

A large variety of cheeses exist in Brazil, reflecting historical and cultural aspects. Brazilian artisanal cheeses present differences in the processing, ripening time (when applied), type of milk used, texture, size, shape, color, moisture content, flavor, the use or not of starter cultures, among others. This review describes the main artisanal cheeses produced in Brazil, focusing on general and particular characteristics associated with their making process and geographical identity. Overall, the high variability of the physicochemical data and deficiency of information on sensorial properties of Brazilian artisanal cheeses were noticed. On the other hand, culture-dependent methods were mostly used to expand the knowledge into the microbiology of these cheeses, whereas their microbial diversity has been recently discovered through the use of 16S rRNA gene sequencing-based methods. The certification of a geographical indication for Brazilian artisanal cheeses may encompass an essential milestone for adding value to these products. Regardless of their significance in the diet, culture, and economy of producing regions, taken together, the reviewed literature discloses the need of insightful studies to generate scientific data to support the expansion of the market, while ensuring the protection of historic aspects related to the production of Brazilian artisanal cheeses.

Selection of indigenous lactic acid bacteria presenting anti-listerial activity, and their role in reducing the maturation period and assuring the safety of traditional Brazilian cheeses.

Artisanal raw milk cheeses are highly appreciated dairy products in Brazil and ensuring their microbiological safety has been a great need. This study reports the isolation and characterization of lactic acid bacteria (LAB) strains with anti-listerial activity, and their effects on Listeria monocytogenes during refrigerated shelf-life of soft Minas cheese and ripening of semi-hard Minas cheese. LAB strains (n = 891) isolated from Minas artisanal cheeses (n = 244) were assessed for anti-listerial activity by deferred antagonism assay at 37 °C and 7 °C. The treatments comprised the production of soft or semi-hard Minas cheeses using raw or pasteurized milk, and including the addition of selected LAB only [Lactobacillus brevis 2-392, Lactobacillus plantarum 1-399 and 4 Enterococcus faecalis (1-37, 2-49, 2-388 and 1-400)], L. monocytogenes only, selected LAB co-inoculated with L. monocytogenes, or without any added cultures. At 37 °C, 48.1% of LAB isolates showed anti-listerial capacity and 77.5% maintained activity at 7 °C. Selected LAB strains presented a bacteriostatic effect on L. monocytogenes in soft cheese. L. monocytogenes was inactivated during the ripening of semi-hard cheeses by the mix of LAB added. Times to attain a 4 log-reduction of L. monocytogenes were 15 and 21 days for semi-hard cheeses produced with raw and pasteurized milk, respectively. LAB with anti-listerial activity isolated from artisanal Minas cheeses can comprise an additional barrier to L. monocytogenes growth during the refrigerated storage of soft cheese and help shorten the ripening period of semi-hard cheeses aged at ambient temperature.

Virulence Genes and Antimicrobial Resistance in Escherichia coli from Cheese Made from Unpasteurized Milk in Brazil.

Cow raw milk cheese is widely eaten in Brazil. These products may be contaminated with pathogenic bacteria. In this work, we investigated the presence of Escherichia coli in raw milk cheese from different States in Brazil. From 147 "Minas" cheese samples, 28 cheeses were positive for E. coli. Among 39 E. coli isolates of the cheeses, one was positive for eae and negative for bpfA and efa1/lifA using PCR, and so was classified as atypical Enteropathogenic E. coli (aEPEC). Two other isolates were positive for extraintestinal pathogenic E. coli (ExPEC) genes. The aEPEC isolate belongs to serogroup O127 and was classified in A phylogenetic group, and ExPEC isolates were found in O73:H12 (EC-2 strain) and O64474:H8 (EC-9 strain) serotype. This ExPEC belongs to A and C phylogenetic group, respectively. Most of E. coli strains belonged to Clermont phylogenetic groups A (28.2%), C, and E (23.1%). Six strains (15.4%) of E. coli were positive for group B1 and two (5.1%) for B2. E. coli isolates presented an aggregative (46.0%) and diffuse (12.6%) adherence pattern to HeLa cells, and the other isolates did not show adhesion (41.4%). Four E. coli isolates (10.3%) were shown to produce moderate biofilm. The antimicrobial resistance rate was tetracycline (25.6%), followed by ampicillin (17.9%), cefoxitin (7.7%), nalidixic acid (5.1%), and amoxicillin-clavulanic acid (2.6%). One strain was resistant to three antimicrobials (tetracycline, ampicillin, and nalidixic acid). The presence of these microorganisms, the O127 strain, and a new serogroup in Brazil is a potential risk for public health.

Bacterial ecology of artisanal Minas cheeses assessed by culture-dependent and -independent methods.

Artisanal Minas cheese is produced in Minas Gerais state, Brazil and its varieties are named according to their geographical origin (Serro, Canastra, Serra do Salitre, Araxá and Campo das Vertentes). The cheese is produced with raw cow's milk and the whey from the previous cheese production ("pingo"). The high economic and cultural importance of artisanal cheese in Brazil justifies the efforts to ensure its safety, quality and provenance. This study aimed to characterize the microbial diversity composition, and geographical distribution of artisanal Minas cheese, focusing on the characterization of its autochthonous lactic acid bacteria (LAB) microbiota. Artisanal Minas cheese varieties from Serro, Canastra, Serra do Salitre, Araxá and Campo das Vertentes were analyzed by culture-dependent (culturing and LAB sequencing) and -independent (repetitive extragenic palindromic-PCR (rep-PCR) and length heterogeneity-PCR, LH-PCR) methods to characterize the microbiota. The microbial counts were variable between cheese samples, and some samples presented high number of coagulase positive bacteria and coliforms that may be associated with hygienic issues. In all samples was observed a prevalence of LAB. 16S rRNA sequencing and rep-PCR of the LAB strains identified four genus (Lactobacillus, Lactococcus, Enterococcus and Weissella), ten species and more than one strain per species. Lactobacillus was the most prevalent genera in all the cheeses. LH-PCR revealed a further six genera and ten species that were not identified by culturing, highlighting the importance of combining both culture-dependent and -independent methods to fully characterize microbiota diversity. Principal component analysis of the LH-PCR data and cluster analysis of rep-PCR data revealed that the artisanal Minas cheese microbiota was influenced not only by their geographical origin but also by the cheese farm. The lack of standardization in the milking and cheese manufacturing procedures between artisanal cheese farms could explain the microbial diversity.

Performance of two alternative methods for Listeria detection throughout Serro Minas cheese ripening

ABSTRACT The ability of pathogens to survive cheese ripening is a food-security concern. Therefore, this study aimed to evaluate the performance of two alternative methods of analysis of Listeria during the ripening of artisanal Minas cheese. These methods were tested and compared with the conventional method: Lateral Flow System™, in cheeses produced on laboratory scale using raw milk collected from different farms and inoculated with Listeria innocua; and VIDAS®-LMO, in cheese samples collected from different manufacturers in Serro, Minas Gerais, Brazil. These samples were also characterized in terms of lactic acid bacteria, coliforms and physical-chemical analysis. In the inoculated samples, L. innocua was detected by Lateral Flow System™ method with 33% false-negative and 68% accuracy results. L. innocua was only detected in the inoculated samples by the conventional method at 60-days of cheese ripening. L. monocytogenes was not detected by the conventional and the VIDAS®-LMO methods in cheese samples collected from different manufacturers, which impairs evaluating the performance of this alternative method. We concluded that the conventional method provided a better recovery of L. innocua throughout cheese ripening, being able to detect L. innocua at 60-day, aging period which is required by the current legislation.

Performance of two alternative methods for Listeria detection throughout Serro Minas cheese ripening

The ability of pathogens to survive cheese ripening is a food-security concern. Therefore, this study aimed to evaluate the performance of two alternative methods of analysis of Listeria during the ripening of artisanal Minas cheese. These methods were tested and compared with the conventional method: Lateral Flow System, in cheeses produced on laboratory scale using raw milk collected from different farms and inoculated with Listeria innocua; and VIDAS®-LMO, in cheese samples collected from different manufacturers in Serro, Minas Gerais, Brazil. These samples were also characterized in terms of lactic acid bacteria, coliforms and physical-chemical analysis. In the inoculated samples, L. innocua was detected by Lateral Flow System method with 33% false-negative and 68% accuracy results. L. innocua was only detected in the inoculated samples by the conventional method at 60-days of cheese ripening. L. monocytogenes was not detected by the conventional and the VIDAS®-LMO methods in cheese samples collected from different manufacturers, which impairs evaluating the performance of this alternative method. We concluded that the conventional method provided a better recovery of L. innocua throughout cheese ripening, being able to detect L. innocua at 60-day, aging period which is required by the current legislation.(AU)

Performance of two alternative methods for Listeria detection throughout Serro Minas cheese ripening.

The ability of pathogens to survive cheese ripening is a food-security concern. Therefore, this study aimed to evaluate the performance of two alternative methods of analysis of Listeria during the ripening of artisanal Minas cheese. These methods were tested and compared with the conventional method: Lateral Flow System™, in cheeses produced on laboratory scale using raw milk collected from different farms and inoculated with Listeria innocua; and VIDAS(®)-LMO, in cheese samples collected from different manufacturers in Serro, Minas Gerais, Brazil. These samples were also characterized in terms of lactic acid bacteria, coliforms and physical-chemical analysis. In the inoculated samples, L. innocua was detected by Lateral Flow System™ method with 33% false-negative and 68% accuracy results. L. innocua was only detected in the inoculated samples by the conventional method at 60-days of cheese ripening. L. monocytogenes was not detected by the conventional and the VIDAS(®)-LMO methods in cheese samples collected from different manufacturers, which impairs evaluating the performance of this alternative method. We concluded that the conventional method provided a better recovery of L. innocua throughout cheese ripening, being able to detect L. innocua at 60-day, aging period which is required by the current legislation.