Abstract

Hygiene failures in meat can be identified based on the evaluation of pathogenic microorganisms, which compromise the microbiological quality of food and can transmit food-borne diseases. The aim of the present study was to evaluate the hygienic quality of beef sold at supermarkets, butcher shops and public markets in the city of Campo Grande, state of Mato Grosso do Sul, Brazil, through the phenotypic and genotypic characterization of Salmonella spp. and Shiga toxin-producing Escherichia coli (STEC) as well as the investigation and quantification of Staphylococcus aureus. Seventy-one samples of beef from 17 commercial establishments were evaluated. Isolates were tested for antimicrobial susceptibility using the disk diffusion method recommended by the Clinical & Laboratory Standards Institute. Salmonella was found in 7.04% of the samples and 70.0% of the isolates were sensitive to the antimicrobials tested. A total of 25.35% of the samples were positive for Staphylococcus aureus, with counts ranging from 1.0 x 10² to 4.3 x 10⁴ CFU/g; these isolates exhibited resistance to penicillin (87.5%), tetracycline (18.75%) and chloramphenicol (6.25%). None of the samples was positive for STEC. The detection of these pathogens in food poses a danger to public health, mainly due to the presence of antimicrobial-resistant isolates. These findings underscore the need for good hygiene and manufacturing practices at retail establishments.

Keywords:
antibiotic; retail trade; food pathogens; resistance.

Resumo

As falhas na qualidade higiênico-sanitária da carne podem ser identificadas a partir da avaliação de microrganismos patogênicos que comprometem a qualidade microbiológica do alimento e podem veicular doenças de origem alimentar. O presente estudo objetivou avaliar a qualidade higiênica-sanitária de carnes bovinas comercializadas em supermercados, açougues e mercados públicos da cidade de Campo Grande (Mato Grosso do Sul, Brasil) por meio da pesquisa e caracterização fenotípica e genotípica de Salmonella spp. e Escherichia coli produtora de toxina Shiga (STEC) e pesquisa e contagem de Staphylococcus aureus. Foram avaliadas 71 amostras de carne bovina de 17 estabelecimentos comerciais que foram submetidas a pesquisa de detecção de Salmonella spp., Escherichia coli produtora de toxina Shiga (STEC) e pesquisa e contagem de Staphylococcus aureus. Os isolados obtidos foram submetidos ao perfil de sensibilidade aos antimicrobianos pelo teste de difusão em disco, de acordo com o Clinical & Laboratory Standards Institute (CLSI). Constatou-se a presença de Salmonella em 7,04% das amostras avaliadas, sendo que 70,0% dos isolados foram sensíveis aos antimicrobianos testados. Em relação ao Staphylococcus aureus, 25,35% das amostras foram positivas com contagens variando entre 1,0 x 10² a 4,3 x 10⁴ UFC/g, sendo que os isolados apresentaram resistência para penicilina (62,5%), tetraciclina (18,75%) e cloranfenicol (6,25%). Nenhuma amostra apresentou-se positiva para STEC. A detecção desses patógenos em alimentos representa um perigo a saúde pública, principalmente, devido a presença de isolados resistentes a antimicrobianos. Além disso, ressalta-se a necessidade do emprego das boas práticas de higiene e fabricação nos estabelecimentos varejistas.

Palavras-chave:
antibiótico; comércio varejista; patógenos alimentares; resistência.

Introduction

In Brazil, the sale of raw beef must meet microbiological requirements determined by the National Health Surveillance Agency (ANVISA)(¹1 Brasil. Agência Nacional de Vigilância Sanitária. Instrução Normativa nº 60, de 23 de dezembro de 2019. Estabelece as listas de padrões microbiológicos para alimentos. Diário Oficial da União. 2019 Dez 26. Seção 1. Português.) as well as the good practices stipulated and monitored by this agency.(²2 Brasil. Agência Nacional de Vigilância Sanitária. Resolução da Diretoria Colegiada n° 216, de 15 de setembro de 2004. Dispõe sobre regulamento técnico de boas práticas para serviços de alimentação. 2004 Set. Seção 1. Português.) Cattle are symptomatic carriers of enteric pathogens, such as Salmonella spp. and Shiga toxin-producing Escherichia coli (STEC) O157:H7 and have bacteria in the microbiota on the hide, such as Staphylococcus aureus, that can be transferred to the carcass during the slaughtering process and contaminate the meat.(³3 Cernicchiaro N, Oliveira ARS, Hoehn A, Cull CA, Noll LW, Shridhar PB, et al. Quantification of Bacteria Indicative of Fecal and Environmental Contamination from Hides to Carcasses. Foodborne Pathog Dis [Internet]. 2019 Dez 1;16(12):844-55. Disponível em: https://doi.org/10.1089/fpd.2019.2656
https://doi.org/10.1089/fpd.2019.2656... ) Beef has intrinsic factors that contribute to bacterial multiplication and can be a vehicle for pathogens to humans,(⁴4 Forsythe SJ. Microbiologia da segurança dos alimentos. 2rd ed. Porto Alegre: Artmed; 2013. 607p. Português.) increasing the risk of food-borne diseases.

Raw beef is reported to be one of the main vehicles for the transmission of food-borne diseases.(⁵5 Who. World Health Organization. Food Safety [Internet]. 2020 Abr 30 [citado 2021 Nov 8]. Disponível em: https://www.who.int/news-room/fact-sheets/detail/food-safety
https://www.who.int/news-room/fact-sheet... ) However, the contribution of meat to such diseases varies from country to country and is dependent on three main factors: the transmitted pathogenic agent, the consumption per capita of beef products and meat cooking and consumption habits in the country.(⁶6 Rhoades JR, Duffy G, Koutsoumanis K. Prevalence and concentration of verocytotoxigenic Escherichia coli, Salmonella enterica and Listeria monocytogenes in the beef production chain: A review. Food Microbiol [Internet]. 2009 Jun;26(4):357-76. Disponível em: https://doi.org/10.1016/j.fm.2008.10.012
https://doi.org/10.1016/j.fm.2008.10.012... ) Epidemiological data reveal that meat was one of the most incriminated in food-borne illness outbreaks in Brazil, according for 5.3% of cases.(⁷7 Brasil. Agência Nacional de Vigilância Sanitária. Surtos de Doenças Transmitidas por Alimentos no Brasil: Informe 2018. 2019 Jun 2 [citado 2021 Dez 12]. Disponível em: portalarquivos2.saude.gov.br ) Some characteristics of retail establishments are considered improper practices that contribute significantly to bacterial development in meat, such as a lack of training of product handlers in good practices, a lack of hygiene in the work area, the use of poorly cleaned utensils and equipment, inadequate temperatures and cross-contamination.(⁸8 Araújo Júnior GM, Pedrosa KYF, Silva HT, Bezerra DC, Coimbra VCS, Improta CTR, et al. Condições de comercialização da carne bovina em mercados municipais e percepção de atores sociais sobre a qualidade. Brazilian Journal of Development [Internet]. 2020 Mar 26;6(3):15369-86. Disponível em: https://doi.org/10.34117/bjdv6n3-421
https://doi.org/10.34117/bjdv6n3-421...

9 ISO. International Organization for Standardization. ISO 6579:2002:24 microbiology of food and animal feeding stuffs: horizontal method for the detection of 25 Salmonella spp. Switzerland. 2002. Disponível em: https://s27415.pcdn.co/wp-content/uploads/2020/01/64ER20-7/Microbial/3-ISO6579-2017-Microbiology-of-the-Food-Chain-Horizontal-Method-for-the-Detection-Enumeration-and-Serotyping-of-Salmonella.pdf. Inglês.
https://s27415.pcdn.co/wp-content/upload...

10 Skyberg JA, Logue CM, Nolan LK. Virulence Genotyping of Salmonella spp. with Multiplex PCR. Avian Dis [Internet]. 2006 Mar;50(1):77-81. Disponível em: https://doi.org/10.1637/7417.1
https://doi.org/10.1637/7417.1...

11 Meng JH, et al. Pathogenic Escherichia coli. In: Downes FP.; Ito K. 2. ed. Compendium 17 of methods for the microbiological examination of foods. Washington: American Public Health Association; 2001. p.331-342. Inglês.

12 Paton JC, Paton AW. Pathogenesis and Diagnosis of Shiga Toxin-Producing Escherichia coli Infections. Clin Microbiol Rev [Internet]. 1998 Jul 1;11(3):450-79. Disponível em: https://doi.org/10.1128/CMR.11.3.450
https://doi.org/10.1128/CMR.11.3.450...

13 Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Instrução Normativa nº 62, de 26 de agosto de 2003. Métodos Analíticos Oficiais para Análises Microbiológicas para Controle de Produtos de Origem Animal e Água. Diário Oficial da União. 2003 Ago. Seção 1. Português.-⁴14 CLSI. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility document M100-S26. 26th ed. Wayne: Clinical and Laboratory Standards Institute; 2016, 177 p. Inglês.)

The aim of the present study was to evaluate the hygienic quality of beef sold at supermarkets, butcher shops and public markets in the city of Campo Grande (state of Mato Grosso do Sul, Brazil) through the phenotypic and genotypic characterization of Salmonella spp. and Shiga toxin-producing Escherichia coli (STEC) as well as the investigation and quantification of Staphylococcus aureus.

Material and Methods

Sample collection

During the period from August 2016 to August 2018, 71 beef samples were collected from different supermarkets, butcher shops and public markets chosen randomly in the city of Campo Grande. The samples were acquired in an approximate quantity of 300 grams each. All products were weighed and wrapped by employees of the establishment using their standard materials in the traditional form of sale to reproduce what normally occurs in the merchant/consumer relationship. Samples were obtained from the butcher section of the stores or directly from refrigerated shelves near the butcher section. All samples were transported in coolers containing recyclable ice.

Preparation of initial sample

A total of 225 mL of 1% buffered peptone water (BPW) were added to 25 ± 0.2 g of each meat sample homogenized for approximately 60 seconds in a “stomacher” and incubated at 37 ± 1º C for 18 ± 2 h. This was considered the initial sample (dilution: 10^-1) for all techniques described below.

Detection of Salmonella spp.

For the detection of Salmonella spp. in the meat samples, the method described in the International Organization for Standardization (ISO 6579:2002)(⁹9 ISO. International Organization for Standardization. ISO 6579:2002:24 microbiology of food and animal feeding stuffs: horizontal method for the detection of 25 Salmonella spp. Switzerland. 2002. Disponível em: https://s27415.pcdn.co/wp-content/uploads/2020/01/64ER20-7/Microbial/3-ISO6579-2017-Microbiology-of-the-Food-Chain-Horizontal-Method-for-the-Detection-Enumeration-and-Serotyping-of-Salmonella.pdf. Inglês.
https://s27415.pcdn.co/wp-content/upload... ) was used with modifications. After enrichment (with BPW), selection (with Muller-Kauffmann tetrathionate broth with novobiocin and Rappaport-Vassiliadis soya broth) and differentiation (with xylose-lysine-deoxycholate agar and Salmonella-Shigella agar), colonies suspected of being Salmonella spp. isolated in nutrient agar were submitted to complementary biochemical tests (indole, urea, motility, lysine decarboxylation, H₂S production, methyl red, Voges-Proskauer, carbohydrate fermentation, citrate and β‑galactosidase).

PCR for confirmation of Salmonella spp.

After incubation at 37 °C for 18-24 horas, strains of Salmonella spp. were sown in TSA medium. A portion of this culture was transferred to microtubes containing 100 μL of sterilized ultrapure water (Milli-Q, Millipore) and centrifuged at 14000 x g for 3 seconds. The extraction of bacterial DNA was performed using the DNeasy Blood & Tissue Kit (QIAGEN, Valencia, CA, USA) following the manufacturer’s instructions. The isolated strains of Salmonella spp. were investigated for the presence of the virulence gene invA, based on Skyberg et al.(¹⁰10 Skyberg JA, Logue CM, Nolan LK. Virulence Genotyping of Salmonella spp. with Multiplex PCR. Avian Dis [Internet]. 2006 Mar;50(1):77-81. Disponível em: https://doi.org/10.1637/7417.1
https://doi.org/10.1637/7417.1... ) The amplified products were applied to 1.5% agarose gel in TBE 0.5 X followed by electrophoresis for approximately 40 minutes at 70 V in a horizontal cube containing TBE 0.5 X. The gel was stained with SYBR Gold (Invitrogen, USA) and the image was recorded using a photodocumentation system.

Detection of Shiga toxin-producing Escherichia coli

The method described in the Compendium of Methods for the Microbiological Examination of Foods (2001)(¹¹11 Meng JH, et al. Pathogenic Escherichia coli. In: Downes FP.; Ito K. 2. ed. Compendium 17 of methods for the microbiological examination of foods. Washington: American Public Health Association; 2001. p.331-342. Inglês.) was used for the detection of STEC in the beef samples.

PCR for investigation of toxin-producing genes

Strains confirmed as E. coli were submitted to PCR for the investigation of the stx1 and stx2 genes following the method described by Paton & Paton.(¹²12 Paton JC, Paton AW. Pathogenesis and Diagnosis of Shiga Toxin-Producing Escherichia coli Infections. Clin Microbiol Rev [Internet]. 1998 Jul 1;11(3):450-79. Disponível em: https://doi.org/10.1128/CMR.11.3.450
https://doi.org/10.1128/CMR.11.3.450... ) The isolated collected from the beef samples and control strains were sown in BHI broth and incubated at 35 °C for 18-24 h. Aliquots of 1 mL of broth were submitted to centrifugation (14,000 x g) for two minutes. Bacterial DNA extraction was performed using the DNeasy Blood & Tissue Kit (QIAGEN, Valencia, CA, USA) following the manufacturer’s instructions. For multiplex PCR, a solution was prepared containing 2.5 µL of Taq buffer 10x, 0.75 µL of MgCl₂ (50 mM), 1.0 µL of dNTP (5 mM), 0.15 µL de Taq DNA polymerase and 3 µL of DNA (approximately 20 ng), with the addition of four pairs of primers (IDT, Integrated DNA Technologies, USA) at concentrations of 10 pmoles and free DNase and RNase ultrapure water (Invitrogen, USA) for a final reaction volume of 25 µL. The amplified products were applied to 1.0% agarose gel in TBE 1 X followed by electrophoresis for approximately 60 minutes at 100 V in a horizontal cube containing TBE 1 X. The gel was stained with SYBR Gold (Invitrogen, USA) and the image was recorded using a photodocumentation system.

Staphylococcus aureus count

The detection and quantification of Staphylococcus aureus were performed using the method described in Normative Instruction n° 62, from August 2003 - Official Analytical Methods for Microbiological Analyses for the Control of Products of an Animal Origin and Water.(¹³13 Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Instrução Normativa nº 62, de 26 de agosto de 2003. Métodos Analíticos Oficiais para Análises Microbiológicas para Controle de Produtos de Origem Animal e Água. Diário Oficial da União. 2003 Ago. Seção 1. Português.)

Antimicrobial susceptibility

The antimicrobial susceptibility of the strains of Salmonella spp. and Staphylococcus aureus was determined according to the Clinical and Laboratory Standards Institute,(¹⁴14 CLSI. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility document M100-S26. 26th ed. Wayne: Clinical and Laboratory Standards Institute; 2016, 177 p. Inglês.) employing the following antimicrobials: cefepime (30 µg), ciprofloxacin (5 µg), chloramphenicol (30 µg), gentamicin (10 µg) and tetracycline (30 µg). Ampicillin (10 µg) and penicillin (10 µg) were also used for Salmonella spp. and Staphylococcus aureus, respectively. The results of the susceptibility profile were interpreted according to the manufacturer’s instructions. Descriptive statistical analysis was performed of sensitivity and resistance to the antimicrobials with the calculation of absolute and relative frequencies. Multiple antibiotic resistance (MAR) was determined following the method described by Krumperman.(¹⁵15 Krumperman PH. Multiple antibiotic resistance indexing of Escherichia coli to identify high-risk sources of fecal contamination of foods. ASM Journals [Internet]. 1983 Jul 1;46(1):165-70. Disponível em: https://doi.org/10.1128/aem.46.1.165-170.1983
https://doi.org/10.1128/aem.46.1.165-170... )

Control strains

Strains from the Health Surveillance Reference Microorganism Collection (CRMVS, FIOCRUZ-INCQS, Rio de Janeiro, RJ, Brazil) were used as negative and positive controls for all techniques: Escherichia coli INCQS 00033 (ATCC 25922), Escherichia coli INCQS 00171 (CDC EDL-933), Salmonella enterica subsp. enterica serovar Enteritidis INCQS 00258 (ATCC 13076) and Salmonella enterica subsp. enterica serovar Typhimurium INCQS 00150 (ATCC 14028). The Staphylococcus aureus ATCC 25923 strain was also used.

Results and Discussion

Among the 71 samples of beef acquired from 17 different establishments, five (7.04%) were positive for Salmonella spp. These five samples were from two supermarkets (A and I) (Table 1). Several studies have reported the occurrence of this pathogen in raw meat sold at retail establishments, with rates ranging from 7.10% to 86.67%.(¹⁷17 Thung TY, Radu S, Mahyudin NA, Rukayadi Y, Zakaria Z, Mazlan N, et al. Prevalence, Virulence Genes and Antimicrobial Resistance Profiles of Salmonella Serovars from Retail Beef in Selangor, Malaysia. Frontiers in Microbiology [Internet] 2018 Jan 11;8: 2697. Disponível em: https://doi.org/10.3389/fmicb.2017.02697
https://doi.org/10.3389/fmicb.2017.02697... ,¹⁸18 Santos PDM, Widmer KW, Rivera WL. PCR-based detection and serovar identification of Salmonella in retail meat collected from wet markets in Metro Manila, Philippines. Plos One [Internet]. 2020 Set 30;15(9):e0239457. Disponível em: https://doi.org/10.1371/journal.pone.0239457
https://doi.org/10.1371/journal.pone.023... ,¹⁹19 Bergamo G, Demoliner F, Timm CD, Carvalho NR, Helbig E, Gandra EA. Formação de biofilmes e resistência a antimicrobianos de isolados de Salmonella spp. Ciência Animal Brasileira [Internet]. 2020 Fev 5;21: e-48029. Disponível em: https://doi.org/10.1590/1809-6891v21e-48029
https://doi.org/10.1590/1809-6891v21e-48... ,²⁰20 Bernardes W da S, Andrade MA, Santos GA, Cardozo SP. Avaliação microbiológica de carne bovina moída de diferentes estabelecimentos comerciais da cidade de Mineiros, Goiás. Braz. J Dev [Internet]. 2020 Mai;6(5):29812-21. Disponível em: https://doi.org/10.34117/bjdv6n5-437
https://doi.org/10.34117/bjdv6n5-437... ,²¹21 Ekli R, Adzitey F, Huda N. Prevalence of resistant Salmonella spp. isolated from raw meat and liver of cattle in the Wa Municipality of Ghana. IOP Conf Ser Earth Environ Sci [Internet]. 2019 Jul 1;287(1):012006. Disponível em: https://doi.org/10.1088/1755-1315/287/1/012006
https://doi.org/10.1088/1755-1315/287/1/... ) This bacterium in meat products poses a risk to consumer health(¹⁶16 EFSA. European Food Safety Authority. Salmonella [Internet]. 2021 [citado 2021 Abr 11]. Disponível em: https://www.efsa.europa.eu/en/topics/topic/salmonella
https://www.efsa.europa.eu/en/topics/top... ) and may demonstrate improper conditions in the obtainment, processing, handling and/or sale of the raw material.(²²22 Silva AA, Amorim BO, Souza MN, Batista CA, Ritter DO, Lanzarin M. Avaliação da qualidade higiênico-sanitária de carne bovina moída exposto à venda. Braz. J Dev [Internet]. 2020 Mar;6(3):10513-25. Disponível em: https://doi.org/10.34117/bjdv6n3-070
https://doi.org/10.34117/bjdv6n3-070... ) Hussain et al.(²³23 Hussain MA, Wang W, Sun, C Gu, L Liu, Z Yu, T, et al. Molecular Characterization of pathogenic Salmonella spp from raw beef in Karachi, Pakistan. Antibiotics [Internet]. 2020 Fev 10; 9(2): 1-15. Disponível em: https://doi.org/10.3390/antibiotics902007
https://doi.org/10.3390/antibiotics90200... ) reported the absence of this microorganism in beef samples from supermarkets with the use of good hygiene practices.

Brazilian legislation determines the absence of Salmonella spp. in 25 grams of raw beef analyzed,(¹1 Brasil. Agência Nacional de Vigilância Sanitária. Instrução Normativa nº 60, de 23 de dezembro de 2019. Estabelece as listas de padrões microbiológicos para alimentos. Diário Oficial da União. 2019 Dez 26. Seção 1. Português.) indicating that the positive meat samples found in the present study were not safe for consumption. The presence of this pathogen in food can cause gastroenteritis, fever and stomach cramps and can lead to more severe cases, especially in children, older people and immunosuppressed individuals.(²⁴24 CDC. Center for Disease Control and Prevention. Salmonella and Food [Internet] .2021 Set 2 [citado 2021 Fev 13]. Disponível em: https://www.cdc.gov/foodsafety/communication/salmonella-food.html#:~:text=Salmonella%20can%20be%20found%20in,it%20can%20make%20you%20sick.
https://www.cdc.gov/foodsafety/communica... )

None of the samples tested in this study was positive for Shiga toxin-producing E. coli (STEC) (Table 1). Only one biochemically positive E. coli isolate was found, which was tested using PCR for the Stx1 and Stx2 genes associated with virulence, but did not present specific fragments for Stx genes. Most of the cases and outbreaks caused by STEC have been attributed to the consumption of beef and pork.(²⁵24 Assis DCS, da Silva TML, Brito RF, da Silva LCG, Lima WG, Brito JCM. Shiga toxin-producing Escherichia coli (STEC) in bovine meat and meat products over the last 15 years in Brazil: A systematic review and meta-analysis. Meat Science [Internet]. 2021 Mar;173:108394. Disponível em: https://doi.org/10.1016/j.meatsci.2020.108394
https://doi.org/10.1016/j.meatsci.2020.1... ,²⁶25 Stephan R, Schumacher S. Resistance patterns of non-O157 Shiga toxinproducing Escherichia coli (STEC) strains isolated from animals, food and asymptomatic human carriers in Switzerland. Letters in Applied Microbiology [Internet]. 2001, 32, 114-117. Disponível em: https://doi.org/10.1046/j.1472-765x.2001.00867.x
https://doi.org/10.1046/j.1472-765x.2001... ) The two Shiga enterotoxins (stx1 and stx2) produced by this bacterial line are responsible for clinical manifestations in patients, such as bloody diarrhea and hemolytic uremic syndrome.(²⁷26 Irino K, Kato MAMF, Vaz TMI, Ramos II, Souza MAC, Cruz AS, Gomes TAT, Vieira MAM, Guth BEC. Serotypes and virulence markers of Shiga toxin-producing Escherichia coli (STEC) isolated from dairy cattle in São Paulo state, Brazil. Veterinary Microbiology [Internet]. 2005, 105, 29-36. Disponível em: https://doi.org/10.1016/j.vetmic.2004.08.007
https://doi.org/10.1016/j.vetmic.2004.08... ,³⁰29 Ristori CA, Rowlands REG, Martins CG, Barbosa ML, dos Santos LF, Jakabi M, et al. Assessment of consumer exposure to Salmonella spp., Campylobacter spp., and Shiga Toxin-Producing Escherichia coli in meat products at retail in the city of São Paulo, Brazil. Foodborne Pathog Dis [Internet]. 2017 Ago;14(8):447-53. Disponível em: https://doi.org/10.1089/fpd.2016.2270
https://doi.org/10.1089/fpd.2016.2270... ) The absence or low prevalence of STEC in beef has also been reported in previous studies.(²⁴24 CDC. Center for Disease Control and Prevention. Salmonella and Food [Internet] .2021 Set 2 [citado 2021 Fev 13]. Disponível em: https://www.cdc.gov/foodsafety/communication/salmonella-food.html#:~:text=Salmonella%20can%20be%20found%20in,it%20can%20make%20you%20sick.
https://www.cdc.gov/foodsafety/communica... ,²⁸27 Who. World Health Organization. E. coli [Internet]. 2018 Fev 7 [citado 2021 Fev 12]. Disponível em: https://www.who.int/news-room/fact-sheets/detail/e-coli
https://www.who.int/news-room/fact-sheet... ,²⁹28 Castro VS, Teixeira LAC, Rodrigues D dos P, dos Santos LF, Conte-Junior CA, Figueiredo EE de S. Occurrence and antimicrobial resistance of E. coli non-O157 isolated from beef in Mato Grosso, Brazil. Trop Anim Health Prod [Internet]. 2019 Jan 19;51(5):1117-23.,³⁰29 Ristori CA, Rowlands REG, Martins CG, Barbosa ML, dos Santos LF, Jakabi M, et al. Assessment of consumer exposure to Salmonella spp., Campylobacter spp., and Shiga Toxin-Producing Escherichia coli in meat products at retail in the city of São Paulo, Brazil. Foodborne Pathog Dis [Internet]. 2017 Ago;14(8):447-53. Disponível em: https://doi.org/10.1089/fpd.2016.2270
https://doi.org/10.1089/fpd.2016.2270... ) One reason for the absence of these strains in meat may be the capacity of this bacterium to enter a viable but non-culturable (VBNC) state, which hinders its detection using conventional methods.(³¹30 Nobili G, Franconieri I, La Bella G, Basanisi MG, La Salandra G. Prevalence of Verocytotoxigenic Escherichia coli strains isolated from raw beef in southern Italy. Int J Food Microbiol [Internet]. 2017 Set;257:201-5. Disponível em: https://doi.org/10.1089/fpd.2016.2270
https://doi.org/10.1089/fpd.2016.2270... ) Meyer-Broseta et al.(³²31 Ding T, Suo Y, Xiang Q, Zhao X, Chen S, Ye X, et al. Significance of viable but nonculturable Escherichia coli: induction, detection, and control. J Microbiol Biotechnol [Internet]. 2017 Mar 28;27(3):417-28. Disponível em: https://doi.org/10.4014/jmb.1609.09063
https://doi.org/10.4014/jmb.1609.09063... ) argue that the prevalence of cattle contaminated by strains of STEC is likely underestimated due to inefficient sampling procedures.

Regarding Staphylococcus aureus, 25.35% (18/71) of the samples were positive, with counts ranging from 1.0 x 10² to 4.3 x 10⁴ colony-forming units (CFUs)/g (Table 1). Likewise, Naas et al.(³³32 Meyer-Broseta, S., Bastian, S.N., Arné, P.D., Cerf, O. & Sanaa, M.. Review of epidemiological surveys on the prevalence of contamination of healthy cattle with Escherichia coli serogroup O157:H7. International Journal of Hygiene and Environmental Health. [Internet]. 2001. 203(4), 347-361. Disponível em: https://doi.org/10.1078/1438-4639-4410041
https://doi.org/10.1078/1438-4639-441004... ) identified the presence of this bacterium in 35.5% of raw beef samples found at retail establishments. Baghbaderani et al.(³⁴33 Naas HT, Edarhoby RA, Garbaj AM, Azwai SM, Abolghait SK, Gammoudi FT, et al. Occurrence, characterization, and antibiogram of Staphylococcus aureus in meat, meat products, and some seafood from Libyan retail markets. Veterinary World [Internet]. 2019 Jun;12(6):925-31. Disponível em: https://doi.org/10.14202/vetworld.2019.925-931
https://doi.org/10.14202/vetworld.2019.9... ) related the high incidence of S. aureus in beef to poor hygiene practices at retail establishments and the excessive, inadequate handling of these products. Although Brazilian legislation does not determine limits for the presence of this pathogen in raw beef,(¹1 Brasil. Agência Nacional de Vigilância Sanitária. Instrução Normativa nº 60, de 23 de dezembro de 2019. Estabelece as listas de padrões microbiológicos para alimentos. Diário Oficial da União. 2019 Dez 26. Seção 1. Português.) the investigation of S. aureus in food products can serve as an indicator of the hygiene and processing practices of commercial establishments.(³⁵34 Baghbaderani ZT, Shakerian A, Rahimi E. Phenotypic and genotypic assessment of antibiotic resistance of Staphylococcus aureus bacteria isolated from retail meat. Infect Drug Resistance [Internet]. 2020 Mai 7;13:1339-49. Disponível em: https://doi.org/10.2147/IDR.S241189
https://doi.org/10.2147/IDR.S241189... ) S. aureus counts up to 10³ CFUs/g may indicate inappropriate hygiene and/or ineffective processing, whereas counts between 10³ and 10⁴ CFUs/g suggest a public health risk and counts of 10⁵ CFUs/g are considered critical, indicating an epidemiological risk, as the production of enterotoxins by the bacterium can occur at this quantity.(³⁶35 CDC. Center for Disease Control and Prevention. Staphylococcal (Staph) Food Poisoning [Internet]. 2018 Ago 9 [citado 2021 Mai 1]. Disponível em: https://www.cdc.gov/foodsafety/diseases/staphylococcal.html#:~:text=Staph%20bacteria%20are%20killed%20by,risky%20if%20contaminated%20with%20Staph.
https://www.cdc.gov/foodsafety/diseases/... )

The analysis of the susceptibility of Staphylococcus aureus isolates to antimicrobials (Figure 1) revealed 62.5% resistance to penicillin (10 µg). However, 100% sensitivity to cefepime (30 µg), ciprofloxacin (5 µg) and gentamicin (10 µg) was found. Among all isolates, the multiple antibiotic resistance (MAR) index ranged from 0.16 to 1.6. Other studies also report the resistance of S. aureus isolates to β-lactam antibiotics, including penicillin(³³32 Meyer-Broseta, S., Bastian, S.N., Arné, P.D., Cerf, O. & Sanaa, M.. Review of epidemiological surveys on the prevalence of contamination of healthy cattle with Escherichia coli serogroup O157:H7. International Journal of Hygiene and Environmental Health. [Internet]. 2001. 203(4), 347-361. Disponível em: https://doi.org/10.1078/1438-4639-4410041
https://doi.org/10.1078/1438-4639-441004... ,³⁶35 CDC. Center for Disease Control and Prevention. Staphylococcal (Staph) Food Poisoning [Internet]. 2018 Ago 9 [citado 2021 Mai 1]. Disponível em: https://www.cdc.gov/foodsafety/diseases/staphylococcal.html#:~:text=Staph%20bacteria%20are%20killed%20by,risky%20if%20contaminated%20with%20Staph.
https://www.cdc.gov/foodsafety/diseases/... ) as well as sensitivity to aminoglycosides, quinolones and tetracyclines.(³⁴33 Naas HT, Edarhoby RA, Garbaj AM, Azwai SM, Abolghait SK, Gammoudi FT, et al. Occurrence, characterization, and antibiogram of Staphylococcus aureus in meat, meat products, and some seafood from Libyan retail markets. Veterinary World [Internet]. 2019 Jun;12(6):925-31. Disponível em: https://doi.org/10.14202/vetworld.2019.925-931
https://doi.org/10.14202/vetworld.2019.9... , ³⁷36 ICMSF. International Committee on Microbiological Specification for Food. Microrganisms in food. 1- Their significance and methods of enumeration. 2. ed. Toronto: University Press, 2000. 439 p. Inglês.) Most isolates (87.5%) were sensitive to chloramphenicol (30 µg), which is in agreement with results described in the study conducted by Irkin et al.,(³⁷36 ICMSF. International Committee on Microbiological Specification for Food. Microrganisms in food. 1- Their significance and methods of enumeration. 2. ed. Toronto: University Press, 2000. 439 p. Inglês.) in which all S. aureus isolates obtained from meat products were sensitive to this antibiotic.

Regarding isolates of Salmonella spp, the MAR index ranged from 0.16 to 0.33. All of these isolates (100%) were sensitive to ampicillin (10 µg), ciprofloxacin (5 µg) and gentamicin (10 µg) (Figure 2). Moreover, 80% exhibited resistance to tetracycline (30 µg).

The sensitivity profile to antimicrobials enables the screening of the propagation of multi-resistant strains.(³⁸37 Irkin R, Bozkurt B, Tumen G. Determination of the prevalence of Salmonella spp. and S. aureus in meat products by Real-Time PCR and testing their antibiotic susceptibility*. Med Weter [Internet]. 2021;77(06):6533-2021. Disponível em: https://doi.org/10.21521/mw.6533
https://doi.org/10.21521/mw.6533... ,³⁹38 Olsen JE, Brown DJ, Skov MN, Christensen JP. Bacterial typing methods suitable for epidemiological analysis applications in investigations of salmonellosis among livestock. Veterinary Quarterly [Internet]. 1993, 15(4), 125-35. Disponível em: https://doi.org/10.1080/01652176.1993.9694390
https://doi.org/10.1080/01652176.1993.96... ) The occurrence of multi-resistance strains of Salmonella spp. in meat at retail establishments has been reported in some studies.¹⁷17 Thung TY, Radu S, Mahyudin NA, Rukayadi Y, Zakaria Z, Mazlan N, et al. Prevalence, Virulence Genes and Antimicrobial Resistance Profiles of Salmonella Serovars from Retail Beef in Selangor, Malaysia. Frontiers in Microbiology [Internet] 2018 Jan 11;8: 2697. Disponível em: https://doi.org/10.3389/fmicb.2017.02697
https://doi.org/10.3389/fmicb.2017.02697... ,¹⁹19 Bergamo G, Demoliner F, Timm CD, Carvalho NR, Helbig E, Gandra EA. Formação de biofilmes e resistência a antimicrobianos de isolados de Salmonella spp. Ciência Animal Brasileira [Internet]. 2020 Fev 5;21: e-48029. Disponível em: https://doi.org/10.1590/1809-6891v21e-48029
https://doi.org/10.1590/1809-6891v21e-48... The high percentage of sensitivity found among the isolates in the present study explains the absence of these strains in the samples analyzed. Likewise, Ekli et al.(²¹21 Ekli R, Adzitey F, Huda N. Prevalence of resistant Salmonella spp. isolated from raw meat and liver of cattle in the Wa Municipality of Ghana. IOP Conf Ser Earth Environ Sci [Internet]. 2019 Jul 1;287(1):012006. Disponível em: https://doi.org/10.1088/1755-1315/287/1/012006
https://doi.org/10.1088/1755-1315/287/1/... ) reported the inhibition of isolates of Salmonella spp. in beef when testing gentamicin and ciprofloxacin. Bergamo et al.(¹⁹19 Bergamo G, Demoliner F, Timm CD, Carvalho NR, Helbig E, Gandra EA. Formação de biofilmes e resistência a antimicrobianos de isolados de Salmonella spp. Ciência Animal Brasileira [Internet]. 2020 Fev 5;21: e-48029. Disponível em: https://doi.org/10.1590/1809-6891v21e-48029
https://doi.org/10.1590/1809-6891v21e-48... ) and Thung et al.(¹⁷17 Thung TY, Radu S, Mahyudin NA, Rukayadi Y, Zakaria Z, Mazlan N, et al. Prevalence, Virulence Genes and Antimicrobial Resistance Profiles of Salmonella Serovars from Retail Beef in Selangor, Malaysia. Frontiers in Microbiology [Internet] 2018 Jan 11;8: 2697. Disponível em: https://doi.org/10.3389/fmicb.2017.02697
https://doi.org/10.3389/fmicb.2017.02697... ) also reported susceptibility to these antimicrobials. This pathogen has lower resistance to fluroquinolone and aminoglycoside antibiotics compared to other enterobacteria.(⁴⁰39 Oueslati W, Rjeibi MR, Mhadhbi M, Jbeli M, Zrelli S, Ettriqui A. Prevalence, virulence and antibiotic susceptibility of Salmonella spp. strains, isolated from beef in Greater Tunis (Tunisia). Meat Science [Internet]. 2016, 119, 154-9. Disponível em: https://doi.org/10.1016/j.meatsci.2016.04.037
https://doi.org/10.1016/j.meatsci.2016.0... )

Conclusion

The presence of Salmonella spp. and Staphylococcus aureus in beef sold at supermarkets poses a direct risk for consumers and may indicate the improper handling of this food. In ten of the 17 establishments sampled, at least one sample of meat was positive for one of the two pathogens studied, underscoring the need for the adoption of more rigorous hygiene practices to reduce the occurrence of contamination of the final product. The only strain of E. coli isolated did not have the stx1 or stx2 genes associated with the virulence of this bacterium. The isolates presented variability in terms of sensitivity to antimicrobials, exhibiting high sensitivity to the majority of antibiotics tested. However, the resistance to some antibiotics underscores the risk of these contaminated foods for consumers.

Acknowledgments

The authors are grateful to Universidade Católica Dom Bosco, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq [National Council of Scientific and Technological Development]) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES [Coordination for the Advancement of Higher Education Personnel]) for financial, personal and physical support.

References

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