PREVALENCE OF ENTEROCOCCUS SPECIES IN CHICKEN MEAT IN SHARKIA GOVERNORATE

Document Type : Original Article

Author

Food Control Department, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44519, Egypt.

Abstract

ABSTRACT
A total of 175 samples of fresh chicken breast, chicken thigh, chicken liver, chicken gizzard, chicken heart, cloacal skin and neck skin (25for each) were randomly collected from different markets and poultry shops at variable sanitation levels in Zagazig city. All collected samples were immediately transferred in an icebox container, aseptically handled and moved promptly to postgraduate student laboratory, Food Control department, Faculty of Veterinary Medicine, Zagazig University, Egypt. The bacteriological examination was applied for enumeration and isolation Enterococcus species.The enterococci detected in chicken samples within different percentages ranged from 15/25(60%) in chicken heart to 25/25(100%) in cloacal skin. The descending prevalence arranged cloacal skin > neck skin > gizzard > liver > thigh > breast > heart. The counts of enterococci ranged from 2.12 to 5.15, 3.19 to 5.64, 3.54 to 5.95, 3.68 to 6.32, 3.11 to 6.26, 4.82 to 6.3 and 3.24 to 6.7 with mean values 3.04 ±0.37, 3.47 ±0.48, 4.05 ±0.38, 4.15 ±0.41, 3.72 ±0.54, 5.03 ±0.13 and 4.8 ±0.25log 10 CFU/gin examined chicken breast, thigh, liver, gizzard, heart, cloacal skin and neck skin, respectively.

Highlights

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Keywords

Main Subjects


Egypt. J. of Appl. Sci., 34 (12) 2019                                              317-323

 

PREVALENCE OF ENTEROCOCCUS SPECIES IN CHICKEN MEAT IN SHARKIA GOVERNORATE

Rasha M.EL-Bayomi1 ;Heba Ahmed Abdallah1;

RehamRagab Abo Elazam1

andElsaid A. Eldaly1

Food Control Department, Faculty of Veterinary Medicine,

Zagazig University, Zagazig 44519, Egypt.

Key Words: Enterococci, Chicken meat, Chicken liver, Enterococcus faecalis, Chicken thigh

ABSTRACT

A total of 175 samples of fresh chicken breast, chicken thigh, chicken liver, chicken gizzard, chicken heart, cloacal skin and neck skin (25for each) were randomly collected from different markets and poultry shops at variable sanitation levels in Zagazig city. All collected samples were immediately transferred in an icebox container, aseptically handled and moved promptly to postgraduate student laboratory, Food Control department, Faculty of Veterinary Medicine, Zagazig University, Egypt. The bacteriological examination was applied for enumeration and isolation Enterococcus species.The enterococci detected in chicken samples within different percentages ranged from 15/25(60%) in chicken heart to 25/25(100%) in cloacal skin. The descending prevalence arranged cloacal skin > neck skin > gizzard > liver > thigh > breast > heart. The counts of enterococci ranged from 2.12 to 5.15, 3.19 to 5.64, 3.54 to 5.95, 3.68 to 6.32, 3.11 to 6.26, 4.82 to 6.3 and 3.24 to 6.7 with mean values 3.04 ±0.37, 3.47 ±0.48, 4.05 ±0.38, 4.15 ±0.41, 3.72 ±0.54, 5.03 ±0.13 and 4.8 ±0.25log 10 CFU/gin examined chicken breast, thigh, liver, gizzard, heart, cloacal skin and neck skin, respectively.

1.INTRODUCTION

Poultry meat products constitute an excellent source of high quality, easily prepared, cooked and digested animal protein, which contains all essential aminoacids besides many vitamins and minerals which are required for human development, hence it represents an important food article in most countries and has a considerable share in Egyptian’s diet for its competitive price with that of other meats (Hussein et al.,2018). Chicken meat is characterized by a lower caloric value as it contains less fat, which is rich in unsaturated fattyacids, so it can be used for feeding young children and some patients. Also they are low in price with a comparison to beef and mutton.

318                                                   Egypt. J. of Appl. Sci., 34 (12) 2019              

 

The consumption of poultry meat is increasing every year and consumers want asafe and a good quality product without the presence of pathogenic microorganisms.Enterococci are Gram-positive, oval cocci, facultative anaerobic bacteria and belong to the group of lactic acid bacteria. Most species are resilient and versatile, being able to survive at 6.5% NaCl, at pH 9.6 and at a wide range of temperatures (10 to 45ºC), with the optimum growth at 35-37ºC (Ludwig et al., 2009). Initially, Enterococcus spp. were considered as harmless commensal inhabitants of the gastrointestinal tract of humans, widely used in the food industry as probiotic or starter cultures (Moreno et al., 2006). However, for the last two decades, enterococci became one of the most common pathogens to be associated with healthcare-associated infections. Enterococci is the dominant commensal in the chicken gut microbiome and an expected contaminant of postharvest or retail chicken (Jackson et al., 2015). The study conducted to evaluate the rate of chicken and giblets contamination with enterococcus species.

2. MATERIALS AND METHODS

2.1- Samples Collection:

A total of 225 samples of fresh chicken breast, chicken thigh, chicken liver, chicken gizzard, chicken heart, cloacal skin and neck skin (25for each) were randomly collected from different markets and poultry shops at variable sanitation levels in Zagazig city. All collected samples were immediately transferred in an icebox container, aseptically handled and moved promptly to postgraduate student laboratory, Food Control department, Faculty of Veterinary Medicine, Zagazig University, Egypt. The bacteriological examination was applied for enumeration and isolation Enterococcus species.

2.2- Preparation of samples and serial dilution according to  ISO 6887-2:(2003) :

Twenty five grams of each sample was homogenized aseptically for 1 min with 225 ml of 0.1 % peptone water in a stomacher (Colworth, 400) then serially dilutedto 10-fold in the same diluent.

2.3- Enterococci count: according to ISO 7899-2 (2000)

Enumeration of Enterococci was carried out on a bile esculin ager (BEA) Himedia (M340). The agar was inoculated by spreading 0.1 ml of the decimal dilution onto the surface. The agar plates were incubated for 24 hrs at 37 ± 0.5°C aerobically.  typical black colonies on the underlying black agar with colony diameters of 1 mm were enumerated as total Enterococci. The Identification of Enterococcus species carried according to Cruickshank et al.(1975)

Egypt. J. of Appl. Sci., 34 (12) 2019                       319

 

3. RESULTS AND DISCUSSION:

Even though it is known that enterococci are ubiquitous organism in the gut, it is one of the emerging organism causing nosocomial infections in humans. Recent studies confirmed enterococci contamination in a wide range of foods including cheese, sausages, meat, milk, and cereals due to improper handling (Koluman et al., 2009). Studies conducted by Olsen et al. (2012) have provided strong evidence that enterococci originating from foods of animal origin had a remarkable degree of similarity in virulence characteristics with human isolates implicating animal meat as an important source for virulent enterococci strains for human colonization.

Table (1) Prevalence of Enterococcus in examined chicken samples(n = 25 of each).

Samples

Number

Percentage

Chicken breast

16

64%

Chichen thigh

19

76%

Chicken liver

21

84%

Chicken gizzard

22

88%

Chicken heart

15

60%

Cloacal skin

25

100%

Neck skin

23

92%

Prevalence of Enterococci in chicken samples:

The data in table 1 and figure 1declared that enterococci detected in chicken samples within different percentages ranged from 15/25(60%) in chicken heart to 25/25(100%) in cloacal skin. The descending prevalence arranged cloacal skin > neck skin > gizzard > liver > thigh > breast > heart. The high prevalence in chicken samples attributed to presence of enterococci in the digestive tract of chicken supports a presumption of meat contamination during the slaughter process in poultry processing plant (Farı´aset al., 1999). The resistance of enterococci to pasteurization temperatures (they belong to the most thermo tolerant microorganisms among non-sporulating bacteria) may tolerate the scalding water temperature (Moreno et al., 2006).

Enterococci previously detected from raw food samples 97% in pork and 100 ground beef (Hayes et al., 2003), frozen chicken 45.2% (Tansuphasiriet al., 2006),retail chicken 95.0%, ground turkey 94.4% , ground beef 92.7%, and pork 85.8% (Tyson et al., 2018). Commensal bacteria, including Enterococcus spp. in commercial livestock and poultry, could contaminate the food chain during processing or find their way into the environment (Diarra et al., 2007). Because of their relative abundance and their resistance to environmental adversity, enterococci have been proposed as indicator indicators for the hygienic quality of food and water (Pierson et al. 2007).

320Egypt. J. of Appl. Sci., 34 (12) 2019              

 

Table (2) Statistical results of Enterococcus count log 10 CFU/g  of examined chicken samples(n = 25 of each).

Samples

Minimum

Maximum

Mean ±SD

Chicken breast

2.12

5.15

3.04 ±0.37c

Chichen thigh

3.19

5.64

3.47 ±0.48bc

Chicken liver

3.54

5.95

4.05 ±0.38b

Chicken gizzard

3.68

6.32

4.15 ±0.41b

Chicken heart

3.11

6.26

3.72 ±0.54bc

Cloacal skin

4.82

6.3

5.03 ±0.13a

Neck skin

3.24

6.7

4.8 ±0.25ab

Means of the same columns carrying different superscript letters are significantly different (P< 0.05).

SE: Standard Error.

The data in table 2 showed that the counts of enterococci ranged from 2.12 to 5.15, 3.19 to 5.64, 3.54 to 5.95, 3.68 to 6.32, 3.11 to 6.26, 4.82 to 6.3 and 3.24 to 6.7 with mean values 3.04 ±0.37, 3.47 ±0.48, 4.05 ±0.38, 4.15 ±0.41, 3.72 ±0.54, 5.03 ±0.13 and 4.8 ±0.25log 10 CFU/gin examined chicken breast, thigh, liver, gizzard, heart, cloacal skin and neck skin, respectively. Enterococci were counted in different food of animal origin 0.5 x 101 and 7.1 x102 CFU/g of minced meat (Klein et al., 1998), 1.2 × 103 – 6.2 × 104 CFU/g and from 0–104 CFU/g in chilled and frozen meat (Šustáčková et al.,  2004), (3.18 log CFU/g)  in organic chicken meat, (2.06 log CFU/g) conventional chicken meat and (1.23 log CFU/g) conventional turkey meat (Miranda et al., 2007).

Cloacal skin significantly higher (p< 0.05) than other examined samples, which attributed to the contamination with the fecal and cecal content during evisceration these results, supported by the finding of Diarra et al., (2010)whom recorded that enterococcus counts were 6.82 ± 0.27 and 5.53± 0.31 log CFU/g of fecal and cecal samples, respectively. Moreover, Enterococci are found in the gastrointestinal tracts of animals, birds, and humans, as well as in soil and water (Hancock and Gilmore 2006). In the human intestine, the density of enterococci ranges from 5 to 8 log CFU/g of intestinal content (Tannock and Cook 2002).

  1. REFERENCES

Cruickshank, R. ;J.Duguid, ;B.Marmion and R. Swain (1975): Medical Microbiology 12th, ed., Edinburg, London and New York.

Egypt. J. of Appl. Sci., 34 (12) 2019                                                    321

 

Diarra, M.S. ; F.G. Silversides ; F. Diarrassouba ; J. Pritchard ; L. Masson and R. Brousseau(2007): Impact of feed supplementation with antimicrobial agents on growth performance of broiler chickens, clostridium perfringens and enterococcus counts, and antibiotic resistance phenotypes and distribution of antimicrobial resistance determinants in Escherichia Coli isolates. Appl Environ Microbiol, 73: 6566-6576

Diarra, M.S. ; H.Rempel ; J. Champagne ; L. Masson ;J. Pritchard and E.Topp (2010):Distribution of Antimicrobial Resistance and Virulence Genes in Enterococcus spp. and Characterization of Isolates from Broiler Chickens. Applied and Environmental Microbiology, 76 (24): 8033–8043.

Farı´as, M.E. ;M.Nun˜ez de Kairuz ;F.Sesma ;J. Palacios ; de Ruiz A.P. Holgadoand G. Oliver (1999): Inhibition of Listeria monocytogenes by thebacteriocinenterocin CRL35 during goat cheese making. Milchwis-senschaft54,30 – 32

Hayes, T. ; K. Haston; M. Tsui; A. Hoang ; C. Haeffeleand A Vonk(2003):Atrazine-induced hermaphroditism at 0.1 ppb in American leopard frogs (Ranapipiens): laboratory and field evidence. Environ Health Perspect.,111 (4): 568-75.

Hussein, M. A., El-Ghareeb, W. R., & Nasr, M. A. (2018): The effect of rosemary extract and lactic acid on the quality of refrigerated broiler fillets. Journal of food science and technology55(12), 5025-5034.

ISO 6887-2: (2003): Microbiology of food and animal feeding stuffs — Preparation of test samples, initial suspension and decimal dilutions for microbiological examination — Part 1-3: Specific rules for the preparation of meat and meat products.

ISO 7899-2 (2000): Water quality -- Detection and enumeration of intestinal enterococci -- Part 2: Membrane filtration method. Geneva, Switzerland.

Jackson, R.C. ; G.M. McFarquhar ;A. Fridlind and R. Atlas(2015): The dependence of cirrus gamma size distributions expressed as volumes in N0-λ-μ phase space and bulk cloud properties on environmental conditions: Results from Small Ice Particles in Cirrus Experiment (SPARTICUS). J. Geophys. Res. Atmos., 120(19): 10351-10377.

322                                                   Egypt. J. of Appl. Sci., 34 (12) 2019              

 

Hancock, L.E. and M.S.Gilmore (2006).Pathogenicity ofEnterococci. In Fischetti RPMNVA, Ferretti JJ, PortnoyDA, Rood JI, eds., Gram-positive pathogens. ASM.Press, Washington, DC, p 299–311.

Klein, J.G. ;R. Ettenson and M.D.Morris (1998):“The animosity model of foreign product purchase: an empirical test in The People’s Republic of China”,Journal of Marketing, 62 (1): 89-100

Koluman, A., Akan, L. S. C., &Akiroglu, F. P. (2009): Occurrence and antimicrobial resistance of enterococci in retail foods. Food Control, 20: 281-283.

Ludwig, W. ;K.H. Schleifer andW.B. Whitman (2009): Family IV. Enterococcaceae fam. nov. In: Vos P., Garrity G. M., Jones D., Krieg N. R., Ludwig W., Rainey F.A., Schleifer K.-H. and Whitman W.B. (Eds) Bergey's Manual of Systematic Bacteriology, Vol. 3, The Firmicutes. (2nd ed.). (pp. 594-623). New York: Springer.

Miranda, J.M. ;M.Guarddon ;A. Mondragon ; B.I. Vázquez ; C.A. Fente ;A. Cepedaand C.M. Franco (2007): Antimicrobial resistance in Enterococcus spp. strains isolated from organic chicken, conventional chicken, and turkey meat: a comparative survey. Journal of food protection70 (4): 1021-1024.‏

Moreno, M.F. ;P.Sarantinopoulos ;E.Tsakalidou and  L. De Vuyst (2006): The role and application of enterococci in food and health. International Journal of Food Microbiology, 106(1): 1-24.

Olsen, R.H. ;H.C. Schønheyder ;H. Christensen andM. Bisgaard (2012): Enterococcus faecalis of human and poultry origin share virulence genes supporting the zoonotic potential of E. faecalis. Zoonoses and Public Health, 59: 256-263.

Pierson, M.D. ; D.L. Zink and L.M. Smoot (2007): Indicator microorganisms and microbiological criteria, p. 69–85. In M. P. Doyle and L. R. Beuchat (ed.), Food microbiology: fundamentals and frontiers, 3rd ed. ASM Press, Washington, DC.

Šustáčková, A. ;E.Nápravníková andJ. Schlegelová (2004): Antimicrobial resistance of Enterococcus spp. isolates from raw beef and meat products. Folia Microbiologica49(4): 411-417.

Egypt. J. of Appl. Sci., 34 (12) 2019                                                    323

 

Tannock, G.W. and G. Cook (2002): Enterococci as members of the intestinal microflora of humans, p. 101–132. In M. S. Gilmore, D. B. Clewell, P. Courvalin, G. M. Dunny, B. E. Murray, and L. B. Rice (ed.), The enterococci: pathogenesis, molecular biology, and antibiotic resistance. ASM Press, Washington, DC.

Tansuphasiri, U. ;D.Khaminthakul and W. Pandii (2006): Antibiotic resistance of enterococci isolated from frozen foods and environmental water.Southeast Asian J Trope MED Public Health.,37 (1): 162-170.

Tyson, J.R. ; N.J. O'Neil ; M. Jain ; H.E. Olsen ; P. Hieter and T.P. Snutch (2018):MinION-based long-read sequencing and assembly extends the Caenorhabditiselegans reference genome. Genome Res., 28(2): 266–274.

مدى تواجد أجناس المکورات السبحیة فى لحوم الدجاج بمحافظة الشرقیة

رشا محمد البیومى1 ، هبة أحمد عبدالله2،ریهام رجب أبوالعزم1 و السعید أبوزید الدالى1

1 قسم مراقبة الأغذیة ، کلیة الطب البیطرى ، الزقازیق مصر.

2 قسم الامراض المشترکة، کلیة الطب البیطرى ، جامعة الزقازیق

تم جمع ما مجموعه 175 عینة من صدور الدجاج الطازج ، فخذ الدجاج ، کبد الدجاج ، قانصة الدجاج ، قلب الدجاج ، وجلد المزرق وجلد العنق (25 لکل منهما) بشکل عشوائی من الأسواق المختلفة ومحلات الدواجن فی مستویات صحیة مختلفة  فی مدینة الزقازیق. تم نقل جمیع العینات التی تم جمعها ونقلها مبردة ، وتم التعامل معها بطریقة معقمة ونقلها على الفور إلى مختبر طلاب الدراسات العلیا ، قسم مراقبة الأغذیة ، کلیة الطب البیطری ، جامعة الزقازیق ، مصر.  تراوحت المکورات المعویة التى تم تحدیدها فی عینات الدجاج ضمن بنسب مختلفة من 15/25 (60٪) فی قلب الدجاج إلى 25/25 (100٪) فی جلد المزرق. وکان الترتیب التنازلی جلد المزرق> جلد العنق> القانصة> الکبد> الفخذ> الصدور> القلب. تراوحت أعداد المکورات المعویة من 2.12 إلى 5.15 ومن 3.19 إلى 5.64 ومن 3.54 إلى 5.95 ومن 3.68 إلى 6.32 ومن 3.11 إلى 6.26 ومن 4.82 إلى 6.3 ومن 3.24 إلى 6.7 مع متوسط القیم 3.04 ± 0.37 و 3.47 ± 0.48 و 4.05 ± 0.38 و 4.15 ± 0.41 ، 3.72 ± 0.54 ، 5.03 ± 0.13 و 4.8 ± 0.25 وحدة لوغاریتمیة/جرام  فی صدر الدجاج الذی تم فحصه ، الفخذ ، الکبد ، القانصة ، القلب ، جلد المزرق وجلد العنق ، على التوالی. وتم تصنیفها عن طریق الأختبارات الکیمیائیة لأنواع المکورات المعویة أنه تم اکتشاف E. faecalis و E.faecium و E. durans و E. avium و E. hirae فی 69 (48.9 ٪) و 50 (35.5 ٪) و 16 (11.4 ٪) و 3 ( 2.1 ٪) و 3 (2.1 ٪) ، على التوالی.

 

  1. REFERENCES

Cruickshank, R. ;J.Duguid, ;B.Marmion and R. Swain (1975): Medical Microbiology 12th, ed., Edinburg, London and New York.

Egypt. J. of Appl. Sci., 34 (12) 2019                                                    321

 

Diarra, M.S. ; F.G. Silversides ; F. Diarrassouba ; J. Pritchard ; L. Masson and R. Brousseau(2007): Impact of feed supplementation with antimicrobial agents on growth performance of broiler chickens, clostridium perfringens and enterococcus counts, and antibiotic resistance phenotypes and distribution of antimicrobial resistance determinants in Escherichia Coli isolates. Appl Environ Microbiol, 73: 6566-6576

Diarra, M.S. ; H.Rempel ; J. Champagne ; L. Masson ;J. Pritchard and E.Topp (2010):Distribution of Antimicrobial Resistance and Virulence Genes in Enterococcus spp. and Characterization of Isolates from Broiler Chickens. Applied and Environmental Microbiology, 76 (24): 8033–8043.

Farı´as, M.E. ;M.Nun˜ez de Kairuz ;F.Sesma ;J. Palacios ; de Ruiz A.P. Holgadoand G. Oliver (1999): Inhibition of Listeria monocytogenes by thebacteriocinenterocin CRL35 during goat cheese making. Milchwis-senschaft54,30 – 32

Hayes, T. ; K. Haston; M. Tsui; A. Hoang ; C. Haeffeleand A Vonk(2003):Atrazine-induced hermaphroditism at 0.1 ppb in American leopard frogs (Ranapipiens): laboratory and field evidence. Environ Health Perspect.,111 (4): 568-75.

Hussein, M. A., El-Ghareeb, W. R., & Nasr, M. A. (2018): The effect of rosemary extract and lactic acid on the quality of refrigerated broiler fillets. Journal of food science and technology55(12), 5025-5034.

ISO 6887-2: (2003): Microbiology of food and animal feeding stuffs — Preparation of test samples, initial suspension and decimal dilutions for microbiological examination — Part 1-3: Specific rules for the preparation of meat and meat products.

ISO 7899-2 (2000): Water quality -- Detection and enumeration of intestinal enterococci -- Part 2: Membrane filtration method. Geneva, Switzerland.

Jackson, R.C. ; G.M. McFarquhar ;A. Fridlind and R. Atlas(2015): The dependence of cirrus gamma size distributions expressed as volumes in N0-λ-μ phase space and bulk cloud properties on environmental conditions: Results from Small Ice Particles in Cirrus Experiment (SPARTICUS). J. Geophys. Res. Atmos., 120(19): 10351-10377.

322                                                   Egypt. J. of Appl. Sci., 34 (12) 2019              

 

Hancock, L.E. and M.S.Gilmore (2006).Pathogenicity ofEnterococci. In Fischetti RPMNVA, Ferretti JJ, PortnoyDA, Rood JI, eds., Gram-positive pathogens. ASM.Press, Washington, DC, p 299–311.

Klein, J.G. ;R. Ettenson and M.D.Morris (1998):“The animosity model of foreign product purchase: an empirical test in The People’s Republic of China”,Journal of Marketing, 62 (1): 89-100

Koluman, A., Akan, L. S. C., &Akiroglu, F. P. (2009): Occurrence and antimicrobial resistance of enterococci in retail foods. Food Control, 20: 281-283.

Ludwig, W. ;K.H. Schleifer andW.B. Whitman (2009): Family IV. Enterococcaceae fam. nov. In: Vos P., Garrity G. M., Jones D., Krieg N. R., Ludwig W., Rainey F.A., Schleifer K.-H. and Whitman W.B. (Eds) Bergey''''''''''''''''''''''''''''''''s Manual of Systematic Bacteriology, Vol. 3, The Firmicutes. (2nd ed.). (pp. 594-623). New York: Springer.

Miranda, J.M. ;M.Guarddon ;A. Mondragon ; B.I. Vázquez ; C.A. Fente ;A. Cepedaand C.M. Franco (2007): Antimicrobial resistance in Enterococcus spp. strains isolated from organic chicken, conventional chicken, and turkey meat: a comparative survey. Journal of food protection70 (4): 1021-1024.‏

Moreno, M.F. ;P.Sarantinopoulos ;E.Tsakalidou and  L. De Vuyst (2006): The role and application of enterococci in food and health. International Journal of Food Microbiology, 106(1): 1-24.

Olsen, R.H. ;H.C. Schønheyder ;H. Christensen andM. Bisgaard (2012): Enterococcus faecalis of human and poultry origin share virulence genes supporting the zoonotic potential of E. faecalis. Zoonoses and Public Health, 59: 256-263.

Pierson, M.D. ; D.L. Zink and L.M. Smoot (2007): Indicator microorganisms and microbiological criteria, p. 69–85. In M. P. Doyle and L. R. Beuchat (ed.), Food microbiology: fundamentals and frontiers, 3rd ed. ASM Press, Washington, DC.

Šustáčková, A. ;E.Nápravníková andJ. Schlegelová (2004): Antimicrobial resistance of Enterococcus spp. isolates from raw beef and meat products. Folia Microbiologica49(4): 411-417.

Egypt. J. of Appl. Sci., 34 (12) 2019                                                    323

 

Tannock, G.W. and G. Cook (2002): Enterococci as members of the intestinal microflora of humans, p. 101–132. In M. S. Gilmore, D. B. Clewell, P. Courvalin, G. M. Dunny, B. E. Murray, and L. B. Rice (ed.), The enterococci: pathogenesis, molecular biology, and antibiotic resistance. ASM Press, Washington, DC.

Tansuphasiri, U. ;D.Khaminthakul and W. Pandii (2006): Antibiotic resistance of enterococci isolated from frozen foods and environmental water.Southeast Asian J Trope MED Public Health.,37 (1): 162-170.

Tyson, J.R. ; N.J. O''''''''''''''''''''''''''''''''Neil ; M. Jain ; H.E. Olsen ; P. Hieter and T.P. Snutch (2018):MinION-based long-read sequencing and assembly extends the Caenorhabditiselegans reference genome. Genome Res., 28(2): 266–274.