Journal of Food and Nutrition Research
ISSN (Print): 2333-1119 ISSN (Online): 2333-1240 Website: http://www.sciepub.com/journal/jfnr Editor-in-chief: Prabhat Kumar Mandal
Open Access
Journal Browser
Go
Journal of Food and Nutrition Research. 2020, 8(1), 63-73
DOI: 10.12691/jfnr-8-1-9
Open AccessArticle

Prevalence of Enterobacteriaceae on Ready to Eat Salads, Drinking Water and Surfaces in Food Markets of Maputo, Mozambique

Glória Alberto Manhique1, 2, , Claudia Titze Hessel1, Erika M DU Plessis3, Stefani Machado Lopes1, Susana de Oliveira Elias1, Eduardo César Tondo1 and Lise Korten3

1Laboratory of Food Microbiology and Food Control, Institute of Food Science and Technology, Federal University of Rio Grande do Sul - ICTA /UFRGS, 9500, Bento Gonçalves Avenue, building 43212, Campus do Vale, Agronomy, Porto Alegre, RS, Brazil

2Technical Higher School - (ESTEC-Mozambique), João Raposo Beirão Street, 135, PO Box, 3276, Maputo/Mozambique

3Centre of Excellence in Food Security, Department of plant and Soil Sciences, University of Pretoria, Hatfield, Pretoria 0002, South Africa

Pub. Date: January 26, 2020

Cite this paper:
Glória Alberto Manhique, Claudia Titze Hessel, Erika M DU Plessis, Stefani Machado Lopes, Susana de Oliveira Elias, Eduardo César Tondo and Lise Korten. Prevalence of Enterobacteriaceae on Ready to Eat Salads, Drinking Water and Surfaces in Food Markets of Maputo, Mozambique. Journal of Food and Nutrition Research. 2020; 8(1):63-73. doi: 10.12691/jfnr-8-1-9

Abstract

Vegetable salads constitute an important component of many meals worldwide. However there is concern for their safety and microbiological quality because they have been implicated in outbreaks of many foodborne diseases, especially in developing countries. In Mozambique, the knowledge of the microbiological quality and virulence genes of bacterial isolates from ready-to-eat (RTE) salads is limited. This study aimed to evaluate the prevalence of Enterobacteriaceae on RTE lettuce, drinking water and surfaces in food markets of Maputo, Mozambique. A total of 35 samples of RTE lettuce salads and 42 drinking water samples were collected from 35 food vendors, in addition to 105 swabs of hands, knives and bowls from seven markets in Maputo City, Mozambique. The prevalence of Enterobacteriaceae bacterial isolates from the collected samples was determined using plate counts method following ISO 21528-2 and ISO 21528-1 (for drinking water). The purified isolates were identified using a matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF-MS). A total of 219 isolates were obtained. Enterobacter isolates (45.2%) were the predominant species. Enterobacteriaceae counts ranged from 0.52 to 6.98log CFU/g. There was no statistically significant correlation between bacteriological counts on RTE lettuce salads and swabs. However, there were significant differences among the numbers of Enterobacteriaceae detected in water for other samples. The prevalence of Escherichia coli was observed in fewer samples, a remarkable tendency of the presence of this bacterium was found in the utensils. The E. coli isolates obtained in this study tested negative for the presence of virulence genes (stx1F, stx1R, stx2F, stx2R). These findings provide valuable background information that can support food safety decisions and confirm that the vast majority of vendors do not sanitize utensils effectively.

Keywords:
food markets indicators MALDI-TOF-MS hygiene quality foodborne pathogens

Creative CommonsThis work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

References:

[1]  Mir, S. A., Shah, M. A., Mir, M. M., Dar, B. N., Greiner, R., & Roohinejad, S. (2018). Microbiological contamination of ready-to-eat vegetable salads in developing countries and potential solutions in the supply chain to control microbial pathogens. Food Control, 85, 235-244.
 
[2]  FDA. (2018). FDA Food Safety Modernization Act (FSMA). Retrieved from https://www.fda.gov/Food/GuidanceRegulation/FSMA/default.htm.
 
[3]  Inyinbor, A. A., Bello, O. S., Oluyori, A. P., Inyinbor, H. E., & Fadiji, A. E. (2019). Wastewater conservation and reuse in quality vegetable cultivation: Overview, challenges and future prospects. Food Control, 98(September 2018), 489-500.
 
[4]  Losio, M. N., Pavoni, E., Bilei, S., Bertasi, B., Bove, D., Capuano, F., … De Medici, D. (2015). Microbiological survey of raw and ready-to-eat leafy green vegetables marketed in Italy. International Journal of Food Microbiology, 210, 88-91.
 
[5]  Tambekar, D. H., & Mundhada, R. H. (2006). Bacteriological quality of salad vegetables sold in Amravati City (India). Journal of Biological Sciences.
 
[6]  Hilborn, E. D., Mermin, J. H., Mshar, P. A., Hadler, J. L., Voetsch, A., Wojtkunski, C., … Slutsker, L. (1999). A multistate outbreak of Escherichia coli O157:H7 infections associated with consumption of mesclun lettuce. Archives of Internal Medicine, 159(15), 1758-1764.
 
[7]  Johnson, R. (2019). Foodborne Illnesses and Outbreaks from Fresh Produce.
 
[8]  Marder, E. P., Griffin, P. M., Cieslak, P. R., Dunn, J., Hurd, S., Jervis, R., … Geissler, A. L. (2018). Preliminary Incidence and Trends of Infections with Pathogens Transmitted Commonly Through Food — Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2006-2017. Morbidity and Mortality Weekly Report Cases, 67(11), 324-328.
 
[9]  FAO/WHO. (2008). Microbiological hazards in fresh fruits and vegetables. Food and Agriculture Organization of the United Nations / World Health Organization.
 
[10]  Van de Venter, T. (2000). Emerging food-borne diseases: a global responsibility. Fna|ana, 26, 4-13.
 
[11]  WHO. (2019). Food safety. Retrieved December 26, 2019, from https://www.who.int/news-room/fact-sheets/detail/food-safety.
 
[12]  Faour-Klingbeil, D., Kuri, V., & Todd, E. (2015). Investigating a link of two different types of food business management to the food safety knowledge, attitudes and practices of food handlers in Beirut, Lebanon. Food Control, 55, 166-175.
 
[13]  Abakari, G., Cobbina, S. J., & Yeleliere, E. (2018). Microbial quality of ready-to-eat vegetable salads vended in the central business district of tamale, Ghana. International Journal of Food Contamination, 5(1).
 
[14]  CFS. (2014). Microbiological Guidelines for Food (Vol. 2014). Queensway, Hong Kong.
 
[15]  Bernasconi, C., Daverio, E., & Ghiani, M. (2003). Microbiology Dimension in EU Water Directives. Ispra.
 
[16]  Baylis, C., Uyttendaele, M., Joosten, H., Davies, A., & Heinz, H. J. (2011). The Enterobacteriaceae and their significance to the food industry. ILSI Europe Report Series. Brussels.
 
[17]  Patel, A. K., Singhania, R. R., Pandey, A., Joshi, V. K., Nigam, P. S., & Soccol, C. R. (2014). Enterobacteriaceae, Coliforms and E.Coli: Introduction. Encyclopedia of Food Microbiology: Second Edition, 1, 659-66.
 
[18]  Smith, J. L., & Fratamico, P. M. (2015). Escherichia coli and Other Enterobacteriaceae: Food Poisoning and Health Effects. Encyclopedia of Food and Health (1st ed.). Elsevier Ltd.
 
[19]  Nagarjun, P. A., & Rao, P. N. (2015). Original Research Article Identification of Novel Food Borne Pathogen , Enterobacteriaceae Bacterium from Fresh Vegetables and Egg Products. International Journal of Current Microbiology and Applied Sciences, 4(7), 54-64.
 
[20]  Alamer, S., Chinnappan, R., & Zourob, M. (2017). Development of Rapid Immuno-based Nanosensors for the Detection of Pathogenic Bacteria in Poultry Processing Plants. Procedia Technology, 27, 23-26.
 
[21]  Elmerdahl Olsen, J. (2000). DNA-based methods for detection of food-borne bacterial pathogens. Food Research International, 33(3-4), 257-266.
 
[22]  Health Protection Agency. (2004). Enumeration of Enterobacteriaceae by the colony count technique. National Standard Method, F 23(1), 1-11.
 
[23]  Cantón, R., & Gómez G. de la Pedrosa, E. (2017). Economic impact of rapid diagnostic methods in Clinical Microbiology: Price of the test or overall clinical impact. Enfermedades Infecciosas y Microbiologia Clinica (English Ed.), 35(10), 659-666.
 
[24]  Cox, K. L. (2011). Immunoassay Development, Optimization and Validation Flow Chart. ImmunoAssay Methods, (Md), 1-38.
 
[25]  Darwish, I. A. (2006). Immunoassay Methods and their Applications in Pharmaceutical Analysis: Basic Methodology and Recent Advances. International Journal of Biomedical Science: IJBS, 2(3), 217-35.
 
[26]  De Boer, E., & Beumer, R. R. (1999). Methodology for detection and typing of foodborne microorganisms. International Journal of Food Microbiology, 50(1-2), 119-130.
 
[27]  Xu, M., Wang, R., & Li, Y. (2017). Electrochemical biosensors for rapid detection of Escherichia coli O157:H7. Talanta, 162(October 2016), 511-522.
 
[28]  Zhao, X., Lin, C. W., Wang, J., & Oh, D. H. (2014). Advances in rapid detection methods for foodborne pathogens. Journal of Microbiology and Biotechnology, 24(3), 297-312.
 
[29]  Bizzini, A., & Greub, G. (2010). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, a revolution in clinical microbial identification. Clinical Microbiology and Infection, 16(11), 1614-1619.
 
[30]  Croxatto, A., Prod’hom, G., & Greub, G. (2012). Applications of MALDI-TOF mass spectrometry in clinical diagnostic microbiology. FEMS Microbiology Reviews, 36(2), 380-407.
 
[31]  Lartigue, M. F. (2013). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for bacterial strain characterization. Infection, Genetics and Evolution, 13(1), 230-235.
 
[32]  Murray, P. R. (2010). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry: Usefulness for taxonomy and epidemiology. Clinical Microbiology and Infection, 16(11), 1626-1630.
 
[33]  NT, M., & I, B. (2015). MALDI-TOF Mass Spectrometry as a Tool for Epidemiological Outbreak Analysis – Can it Work? Journal of Medical Diagnostic Methods, 04(04).
 
[34]  Rodríguez-Sánchez, B., Alcalá, L., Marín, M., Ruiz, A., Alonso, E., & Bouza, E. (2016). Evaluation of MALDI-TOF MS (Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry) for routine identification of anaerobic bacteria. Anaerobe, 42, 101-107.
 
[35]  Angeletti, S. (2017, July 1). Matrix assisted laser desorption time of flight mass spectrometry (MALDI-TOF MS) in clinical microbiology. Journal of Microbiological Methods. Elsevier B.V.
 
[36]  Cattani, M. E., Posse, T., Hermes, R. L., & Kaufman, S. C. (2015). Identificación rápida de microorganismos de frascos de hemocultivos por espectrometría de masas. Comparación de 2 procedimientos diagnósticos. Revista Argentina de Microbiologia, 47(3), 190-195.
 
[37]  Faron, M. L., Buchan, B. W., & Ledeboer, N. A. (2019). Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Use with Positive Blood Cultures: Methodology, Performance, and Optimization. Journal of Clinical Microbiology, 32(1), 1-29.
 
[38]  Steensels, D., Verhaegen, J., & Lagrou, K. (2011, May). Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for the identifi cation of bacteria and yeasts in a clinical microbiological laboratory: A review. Acta Clinica Belgica.
 
[39]  Yang, Y., Lin, Y., & Qiao, L. (2018). Direct MALDI-TOF MS Identification of Bacterial Mixtures. Analytical Chemistry, 90(17), 10400-10408.
 
[40]  Macaza, B. S. (2017). Avaliação da qualidade e segurança microbiológica de alimentos de rua vendidos nos mercados municipais da cidade de Nampula, Moçambique. Mestrado em Alimentação Coletiva. Universidade do Porto.
 
[41]  Shiningeni, D., Chimwamurombe, P., Shilangale, R., & Misihairabgwi, J. (2019). Prevalence of pathogenic bacteria in street vended ready-to-eat meats in Windhoek, Namibia. Meat Science, 148, 223-228.
 
[42]  Puerta-García, A., & Mateos-Rodríguez, F. (2010). Enterobacterias. Medicine, 10(51), 3426-3431.
 
[43]  Cordier, J.-L. (2006). Enterobacteriaceae. Emerging Foodborne Pathogens.
 
[44]  Sahuquillo-Arce, J. M., Chouman-Arcas, R., Molina-Moreno, J. M., Hernández-Cabezas, A., Frasquet-Artés, J., & López-Hontangas, J. L. (2017). Capnophilic Enterobacteriaceae. Diagnostic Microbiology and Infectious Disease, 87(4), 318-319.
 
[45]  Bagley, S. T. (1985). Habitat association of Klebsiella species. Infection Control.
 
[46]  Eugene Sanders, W. E., & Sanders, C. C. (1997). Enterobacter spp.: Pathogens poised to flourish at the turn of the century. Clinical Microbiology Reviews, 10(2), 220-241.
 
[47]  Guentzel, M. N. (1996). Escherichia, Klebsiella, Enterobacter, Serratia, Citrobacter,and Proteus. Medical Microbiology. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21413290.
 
[48]  Liu, S., & Kilonzo-Nthenge, A. (2017). Prevalence of multidrug-resistant bacteria from U.S.-grown and imported fresh produce retailed in chain supermarkets and ethnic stores of Davidson County, Tennessee. Journal of Food Protection, 80(3), 506-514.
 
[49]  Paudyal, N., Anihouvi, V., Hounhouigan, J., Matsheka, M. I., Sekwati-Monang, B., Amoa-Awua, W., … Fang, W. (2017). Prevalence of foodborne pathogens in food from selected African countries - A meta-analysis. International Journal of Food Microbiology, 249, 35-43.
 
[50]  Puspanadan, S., Afsah-Hejri, L., Loo, Y. ., Nillian, E., Kuan, C. ., Goh, S. G., … Nishibuchi, M. (2012). Detection of Klebsiella pneumoniae in raw vegetables using Most Probable Number-Polymerase Chain Reaction (MPN-PCR). International Food Research Journal, 19(4), 1757-1762.
 
[51]  WHO. (2011). Guidelines for Drinking-water Quality (Fourth). Switzerland: WHO.
 
[52]  Dos Reis, R. S., & Horn, F. (2010). Enteropathogenic Escherichia coli, Samonella, Shigella and Yersinia: Cellular aspects of host-bacteria interactions in enteric diseases. Gut Pathogens, 2(1).
 
[53]  Ssemanda, J. N., Reij, M., Bagabe, M. C., Muvunyi, C. M., Joosten, H., & Zwietering, M. H. (2017). Indicator microorganisms in fresh vegetables from “farm to fork” in Rwanda. Food Control, 75, 126-133.
 
[54]  ICMSF. (2006). A Simplified Guide to Understanding and Using Food Safety Objectives and Performance Objectives. ICMSF.
 
[55]  Najafi, M. B. H., & Bahreini, M. (2012). Microbiological Quality of Mixed Fresh-Cut Vegetable Salads and Mixed Ready- to-Eat Fresh Herbs in Mashhad , Iran. International Conference on Nutrition and Food Sciences IPCBEE, 39(2012), 62-66. Retrieved from http://ipcbee.com/vol39/012-ICNFS2012-N022.pdf.
 
[56]  Denis, N., Zhang, H., Leroux, A., Trudel, R., & Bietlot, H. (2016). Prevalence and trends of bacterial contamination in fresh fruits and vegetables sold at retail in Canada. Food Control, 67, 225-234.
 
[57]  Kundu, A., Wuertz, S., & Smith, W. A. (2018). Quantitative microbial risk assessment to estimate the risk of diarrheal diseases from fresh produce consumption in India. Food Microbiology, 75, 95-102.
 
[58]  Food Standards Australia New Zealand. (2018). Compendium of microbiological criteria for food. Compendium of Microbiological Criteria for Food.
 
[59]  Azevedo, P. A. A., Furlan, J. P. R., Oliveira-Silva, M., Nakamura-Silva, R., Gomes, C. N., Costa, K. R. C., … Pitondo-Silva, A. (2018). Detection of virulence and β-lactamase encoding genes in Enterobacter aerogenes and Enterobacter cloacae clinical isolates from Brazil. Brazilian Journal of Microbiology, 49, 224-228.
 
[60]  Soltan Dallal, M. M., Shojaei, M., Sharifi Yazdi, M. K., & Vahedi, S. (2015). Microbial contamination of fresh vegetable and salad samples consumed in Tehran, Iran. Journal of Food Quality and Hazards Control, 2(4), 139-143.
 
[61]  Tallon, P. A. M., Magajna, B., Lofranco, C., & Leung, K. A. M. T. I. N. (2005). MICROBIAL INDICATORS OF FAECAL CONTAMINATION IN WATER : A CURRENT PERSPECTIVE Ensuring the safety of drinking water is an ongoing process . In developed coun- tries , drinking water regulations require the monitoring of numerous chemical and microbiologic. Public Health, 166(Table I), 139-166.
 
[62]  Chauhan, A., Goyal, P., Varma, A., & Jindal, T. (2017). Microbiological evaluation of drinking water sold by roadside vendors of Delhi, India. Applied Water Science, 7(4), 1635-1644.
 
[63]  Onyango, A. E., Okoth, M. W., Kunyanga, C. N., & Aliwa, B. O. (2018). Microbiological Quality and Contamination Level of Water Sources in Isiolo County in Kenya. Journal of Environmental and Public Health, 2018.
 
[64]  Yousefi, M., Saleh, H. N., Yaseri, M., Mahvi, A. H., Soleimani, H., Saeedi, Z., … Mohammadi, A. A. (2018). Data on microbiological quality assessment of rural drinking water supplies in Poldasht county. Data in Brief, 17, 763-769.
 
[65]  WHO. (1997). Guidelines for drinking-water quality (Vol. 3). Geneva.
 
[66]  WHO. (2018a). Drinking-water. Retrieved September 21, 2018, from http://www.who.int/news-room/fact-sheets/detail/drinking-water.
 
[67]  Jafari, K., Mohammadi, A. A., Heidari, Z., Asghari, F. B., Radfard, M., Yousefi, M., & Shams, M. (2018). Data on microbiological quality assessment of rural drinking water supplies in Tiran County, Isfahan province, Iran. Data in Brief, 18, 1122-1126.
 
[68]  Dewaal, C. S., Robert, N., Witmer, J., & Tian, X. A. (2010). A Comparison of the Burden of Foodborne and Waterborne Diseases in Three World Regions , 2008. Food Protection Trends, 30(8), 483-490.
 
[69]  Mengel, M. A., Delrieu, I., Heyerdahl, L., & Gessner, B. D. (2014). Cholera Outbreaks in Africa (pp. 117-144).
 
[70]  Nienie, A. B., Sivalingam, P., Laffite, A., Ngelinkoto, P., Otamonga, J. P., Matand, A., … Poté, J. (2017). Microbiological quality of water in a city with persistent and recurrent waterborne diseases under tropical sub-rural conditions: The case of Kikwit City, Democratic Republic of the Congo. International Journal of Hygiene and Environmental Health, 220(5), 820-828.
 
[71]  WHO. (2018b). Guidelines on sanitation and health. World Health Organization. Retrieved from
 
[72]  https://apps.who.int/iris/bitstream/handle/10665/274939/9789241514705-eng.pdf?ua=1.
 
[73]  Lues, J. F. R., & Van Tonder, I. (2007). The occurrence of indicator bacteria on hands and aprons of food handlers in the delicatessen sections of a retail group. Food Control, 18(4), 326-332.
 
[74]  Kilonzo-Nthenge, A., Rotich, E., Godwin, S., Nahashon, S., & Chen, F. (2012). Prevalence and antimicrobial resistance of cronobacter sakazakii isolated from domestic kitchens in middle Tennessee, United States. Journal of Food Protection, 75(8), 1512-1517.
 
[75]  Rakhshkhorshid, M., Rakhshkhorshid, A., & Belarak, D. (2016). Survey of cooking utensils and dishes microbial contamination rate in the cafeteria of Zahedan University of medical sciences, 2015. International Journal of Biomedical and Healthcare Science, 6(2), 187-193.
 
[76]  Alum, Akanele, E., Mgbo, S., Chukwu, O., & Ahudie, C. M. (2016). Microbiological Contamination Of Food: The Mechanisms, Impacts And Prevention. International Journal of Scientific & Technology Research, 5(3), 65-78.
 
[77]  Nasrolahei, M., Mirshafiee, S., Kholdi, S., Salehian, M., & Nasrolahei, M. (2017). Bacterial assessment of food handlers in Sari City, Mazandaran Province, north of Iran. Journal of Infection and Public Health, 10(2), 171-176.
 
[78]  Honua, M. H. M. (2018). The bacterial contamination of food handlers hands in Wad madani city restaurants, Sudan. International Journal Of Community Medicine And Public Health, 5(4), 1270.
 
[79]  Mengist, A., Mengistu, G., & Reta, A. (2018). Prevalence and antimicrobial susceptibility pattern of Salmonella and Shigella among food handlers in catering establishments at Debre Markos University, Northwest Ethiopia. International Journal of Infectious Diseases, 75, 74-79.
 
[80]  Gebreyesus, A., Adane, K., Negash, L., Asmelash, T., Belay, S., Alemu, M., & Saravanan, M. (2014). Prevalence of Salmonella typhi and intestinal parasites among food handlers in Mekelle University student cafeteria, Mekelle, Ethiopia. Food Control, 44, 45-48.
 
[81]  Alhashimi, H. M. M., Ahmed, M. M., & Mustafa, J. M. (2017). Nasal carriage of enterotoxigenic Staphylococcus aureus among food handlers in Kerbala city. Karbala International Journal of Modern Science, 3(2), 69-74.
 
[82]  Castro, A., Santos, C., Meireles, H., Silva, J., & Teixeira, P. (2016). Food handlers as potential sources of dissemination of virulent strains of Staphylococcus aureus in the community. Journal of Infection and Public Health, 9(2), 153-160.
 
[83]  Karaye, G., Karaye, K., & Kaze, P. (2019). Detection of Escherichia Coli in Freshly Harvested Spinach Samples Collected from Five Different Markets in Zaria. American Journal of Biomedical Science & Research, 4(2), 112-115.
 
[84]  Reuben, C. R., & Makut, M. D. (2014). Occurrence of Escherichia coli O157 : H7 in vegetables grown and sold in Lafia metropolis , Nigeria. Wordl Hournal of Microbiology, 1(3), 17-21.
 
[85]  Saeed, A. Y. (2013). Detection of Escherichia coli O157 in vegetables. IOSR Journal of Agriculture and Veterinary Science, 6(2), 16-18.
 
[86]  Shakerian, A., Rahimi, E., & Emad, P. (2016). Vegetables and restaurant salads as a reservoir for Shiga toxigenic Escherichia coli: Distribution of virulence factors, O-serogroups, and antibiotic resistance properties. Journal of Food Protection, 79(7), 1154-1160.
 
[87]  Maistro, L. C., Miya, N. T. N., Sant’Ana, A. S., & Pereira, J. L. (2012). Microbiological quality and safety of minimally processed vegetables marketed in Campinas, SP - Brazil, as assessed by traditional and alternative methods. Food Control, 28(2), 258-264.
 
[88]  Uzeh, R. E., & Adepoju, A. (2013). Incidence and survival of Escherichia coli O157: H7 and Listeria monocytogenes on salad vegetables. International Food Research Journal, 20(4), 1921-1925.
 
[89]  Entani, E., Asai, M., Tsujihata, S., Tsukamoto, Y., & Ohta, M. (1998). Antibacterial action of vinegar against food-borne pathogenic bacteria including Escherichia coli O157:H7. Journal of Food Protection, 61(8), 953-959.
 
[90]  Lee, S. Y., Rhee, M. S., Dougherty, R. H., & Kang, D. H. (2010). Antagonistic effect of acetic acid and salt for inactivating Escherichia coli O157:H7 in cucumber puree. Journal of Applied Microbiology, 108(4), 1361-1368.
 
[91]  Sulaiman, M. A., Musa, B., Paul, M., Aliyu, M. S., & Tijjani, M. B. (2016). Potential Risk of Transmitting Escherichia coli O157 : H7 through Some Vegetables Sold in Zaria Metropolis. Ujmr, 1(1), 169-174.