- Email: [email protected]
Identification of micrococcaceae isolated from goat's milk and cheese in the Poitou-Charentes region
International
Journal of
Food Microbiology 30 (1996) 373-378
Short communication
Identification of micrococcaceae isolated from goat’s milk and cheese in the Poitou-Charentes region C. Vernozy Rozanda,*, C. Mazuy”, G. Perrinb, F. Haond”, M. Bes”, Y. Brun”, J. Fleurette” “Unitt de Microbiologic, .kpidkmiologie Moltkulaire, Bourgelat, B.P. 83, F-69280 “Station Rkgionale Caprine ‘Centre National de REfGence des
l&ColeNationale VSrinaire de Lyon, I avenue Marcy l’l?toile, France de Niort, Niort, France Staphylocoques, Lyon, France
Received 30 November 1994; revised 1 July 1995; accepted 26 July 1995
Abstract
One hundred and ninety strains of coagulase-negative staphylococci were isolated from goat’s milk, whey and cheese at various stages of manufacture. Sixteen different coagulase negative Staphylococci (CNS) species were recovered, 3 of which were predominant: Staphylococcus simulans, Staphylococcus epidermidis and Staphylococcus xylosus.
The prevalent species were recovered at least at two different stages of cheese manufacturing, suggesting a better adaptation to the environment. After 15 days of ripening, the cheeses showed lower counts of Micrococcaceae. Keywords: Coagulase-negative
* Corresponding
staphylococci;
author. Telephone:
Milk; Cheese; Goat
+ 33 78872553; fax: + 33 78872554.
0168-1605/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved PII SO168-1605(96)00953-l
314
C. Vernozy Rozand et al. / ht. J. Food Microbiology 30 (1996) 373-378
1. Introductiml Most goat’s milk cheeses in France are produced in the Poitou-Charentes region. Bacteriological standards have been established for the manufacture of goat’s raw milk cheese including Staphylococcus aureus counts of less than 100 CFU per gm of cheese. Coagulase-negative staphylococci pose no public health risk and are not mentioned in the regulations. However, enterotoxigenicity of coagulase negative staphylococci isolated from goat’s milk has been reported (Valle et al., 1990; Orden et al., 1992). Coagulase-negative staphylococci have often been isolated from goat’s milk, with or without association of mastitis (Smith and Roguinsky, 1977; Petersen, 1981; Lerondelle and Pcnttrel, 1984; Poutrel, 1984; De Buyser et al., 1987; Harvey and Gilmour, 1985; B&Ii-Madani et al., 1992). The object of this study was to’ identify the dominant species of coagulase-negative staphylococci in goat’s milk cheese and investigate the possible differences in the distribution of Micrococcaceae species in milk, whey and cheese.
2. Materials and methods
2.1. Samp Iing Eighteen batches of semi-processed raw goat-milk cheeses were investigated in the Poitou-Charentes region. Samples were obtained from each of the following steps of processing: the milk used for cheese making; the curds of the day of milk curdling (cheese day 0 = LC DO); whey at curdling; cheeses at 7 days after curdling (LC D7) and 15 days after curdling (LC D15). Twenty-two processed cheeses sampled 15 days after curdling, corresponding to 22 different cheese makings, were also analysed. 2.2. Bacteriological analyses 2.2.1. Isolation of strains
Twenty-five ,ul of milk or whey were inoculated by streaking onto Staphylococcus Selective media No. 110 act to CHAPMAN (ref 5469, Merck, Darmstadt, Germany). Ten grams of cheese surface and interior were homogenized with 90 ml tryptone salt (tryptone 1,0 g, NaCl 8,5 g, HZ0 1 000 ml); 0.1 ml were surface spread on the agar medium. The plates were incubated for 72 h at 37°C. Subculturing onto trypto-casein soya agar (ref 64554, Sanofi Diagnostics Pasteur, Marnes la Coquette, France) was carried out for each type of colony encountered. Only pure cultures of Gram-positive and catalase-positive cocci were retained for identification as described below. 2.2.2. IdentiJications
Three tests were used to differentiate Micrococci and Staphylococci: (i) acid production from glycerol (Schleifer and K.loos (1975)) and Brun and Bes (1990)), on
C. Vernozy Rozand et al. /ht.
J. Food Microbiology 30 (1996) 373-378
315
Bacto purple agar (ref 0228-17-7, Difco, Detroit, Michigan, USA) containing 1% glycerol; (ii) susceptibility to lysozyme (Schleifer and Kloos, 1975) using MuellerHinton medium (ref 51075, bioMCrieux, Marcy l’Etoile, France) to which a drop of 400 pgg/ml lysozyme solution (ref L.6876, Sigma chemical, CO, PO box, 14508 St Louis, MO 63178 USA) was added; (iii) and susceptibility to nitrofurantoin (Hebert and Caillet, 1983) examined on Mueller-Hinton medium (bioMCrieux) with discs contained 300 rug of nitrofurantoin (ref 68678, Sanofi Diagnostics Pasteur). For identification of isolates to species level, the following tests were carried out: (i) coagulase using rabbit plasma (bioMerieux), according to the tube method of Vuillemin et al. (1985); (ii) the Staphylase test@ (ref DR 595A, Oxoid, Unipath limited, Wade Road, Basingstoke, Hampshire, RG24 8PW, England); (iii) novobiocin susceptibility using discs containing 5 pg novobiocin (ref 56350, Sanofi Diagnostics Pasteur, Marnes la Coquette, France), according to the technique of Almeida and Jorgensen (1982) and (iv) the ID 32 STAPH system (ref 32500, bioMCrieux, Marcy l’Etoile, France) including 26 substrates.
3. Results and discussion The colonies of Gram-positive and catalase-positive cocci observed varied as follows. For the milk samples examined, five showed only one type of colony, 11 revealed 2-3 different types of colonies and two revealed five different types of colonies. For nine of the 18 whey samples examined, Micrococcuceae were not detected; three samples revealed only one type of colony, five showed two different types of colonies and one showed three different types of colonies. On day 0 and 7, the cheeses contained two to four different types of colonies, whereas on day 15, only one colony type was seen. Of the 233 strains isolated, 190 were coagulase-negative staphylococci, 22 were coagulase positive, and 21 were micrococci (Table 1). The coagulase-positive Staphylococci all belonged to the S. aureus. Three of the 16 different coagulase negative staphylococci species detected appeared predominant (Table 2) i.e. S. simulans (51 strains); S. epidermidis (31 strains) and S. xylosus (20 strains). Table 1
C.N.S.b
C.P.S.’ Micrococcus spp
Milk (18)
Whey (IS)”
Cheese (76)”
Total (112)”
39 3
18 1
133 18
190 22
5
2
14
21
“No. of samples. %Z.N.S., coagulase-negative staphylococci. ‘C.P.S., coagulase-positive staphylococci.
376
C. Vernozy Rozand et al. 1 Int. J. Food Microbiology
30 (19%)
373-378
Table 2
Species
Milk
Whey
C* Day 0
C* Day 7
C* Day15
Total
1
1 3 0 1 17 0 1 0 0 2 0 0 1 16 2
3 2 2 18
4 1 50
0 0 0 1 2 2 0 0 0 0 3 1 0 10 0 3 4 8 34
0 5 0 0 4 1 0 1 0 1 1 0 0 22 3 1 3 7 49
2 10 1 2 31 4 1 1 7 6 9 1 1 51 6 20 16 21 190
CNS” S. auricularis S. capitis S. chromogenes S. cohnii S. epidermidis S. equorum S. gallinarum S. hominis S. lentus S. lugdunensis S. saprophyticus S. sciuri S. schleiferi S. simulans S. warneri s. xylosus S. xylosus/S. equorum
0
Unidentifed Staphylococcus Total CNS
1 2 0 0 7 0 0 0 I 3 0 0 0 1 0 12 3 3 39
Staphylococcus
3
8
0
10
22
0
0 0 1 0 2 3
0 2 2 0 1 5
1 2 0 0 3 6
1 5 4 2 9 21
aureus
Micrococcus M. nishinomiyaensis h4. roseus M. lylae M. varians unidentified Micrococcus
Total Micrococcus C*, lactic cheese. CNS**, coagulase-negative
1 1 0 3 5
0
1 0 1 1 0 0 0 0 5 0 0 2
1
staphylococci.
A further 16 strains in the S.xylosus/S.equorum group were isolated. Twenty-one coagulase negative staphylococci were unidentifiable. Staphylococcus simulans was identified in 16 different batches of cheese manufacturing; in seven of them, it was detected at two different stages and in seven others at three different stages of the cheese manufacturing. (results not shown). Strains of S. xylosus, S. equorum and S. xylosuslequorum were recovered from 15 batches; in six of them at two different stages of manufacture; in six others at three different stages and two others at four different stages (results not shown). Staphylococcus epidermidis were found in 15 batches; in three of them at two different stages of manufacture; in five at three other different stages and one at four different stages. The other coagulase-negative staphylococci identified were detected mostly at only one stage of manufacture (results not shown).
C. Vemozy Rozand et al. /ht.
J. Food Microbiology 30 (1996) 373-378
311
During the ripening, dry matter and pH of the cheeses varied from 20.3% to 44.2% and from 4.43% to 4.49%, respectively (unpublished results). The results obtained are similar to those found by Poutrel (1984), De Buyser et al. (1987) and Harvey and Gilmour (1988). No S. cuprae were detected during the present study, although this species had been recovered by the authors just mentioned above and by Bedidi-Madani et al. (1992) and Valle et al. (1991). This diverging result may be explained by the use of a selective medium that did not allow the recovery of S. caprae. Eleven percent of the coagulase-negative staphylococci could not be identified by the identification tests used. This percentage is close to that reported in other studies of goat’s milk (Poutrel, 1984; Perrin-Coullioud et al., 1991; Deinhoffer and Pernthaner, 1993). The predominant species, S. simulans, S. epidermidis and S. xylosus, were recovered at different stages of cheese manufacture indicating that they are welladapted to the cheese environment, i.e. pH, water activity, NaCl and nutrients (Tatini, 1973, Stadhouders et al., 1978, Santos and Genigeorgis, 1981).
Acknowledgements This work was supported by a grant’ from the Ministry of Agriculture and Fisheries and also by funds from bioMCrieux.The authors wish to thank Sylvie Ray-Gueniot for her contribution to this study.
References Almeida, R.F. and Jorgensen, J.M. (1982) Use of Mueller-Hinton agar to determine novobiocin susceptibility of coagulase negative staphylococci. J. Clin. Microbial. 16, 1155-l 156. Bedidi-Madani, N., Richard, Y., Borges, E. and Lerondelle, C. (1992) Identification et sensibilite aux antibiotiques des staphylocoques coagulase negative isoles de lait de chevre. Revue Med. Vet. 143, 539-545. Brun, Y. and Bes, M. (1990) Methodes diagnostiques des staphylocoques coagulase-ntgatifs. Med. Mal. Inf. Tome 2, Hors s&e Mars, 16-23. De Buyser, M.L., Dilasser, F., Hummel, R. and Bergdoll, M.S. (1987) Enterotoxin and toxic-shock syndrome toxin 1 production by staphylococci isolated from goats-milk. Int. J. Food Microbial. 5, 301-309. Deinhoffer, M. and Pernthaner, A. (1993) Differentiation of staphylococci from ewe and goat milk samples. Dtsch. tierlrztl. Wschr. 100, 234-236. Harvey, J. and Gilmour, A. (1985) Application of current methods for isolation and identification of staphylococci in raw bovine milk. J. Appl. Bacterial. 59, 2077221. Harvey, J. and Gilmour, A. (1988) Isolation and characterisation of staphylococci from goats milk produced in Northern Ireland. Lett. Appl. Microbial. 7, 79982. Hebert, J.P. and Caillet, R. (1983) Differentiation entre Microcoques et Staphylocoques par l’etude de la sensibilite a la nitrofurantome (N(SNitro-2furfurylidene-lamino-(hydrantoi’ne)). Pathol. Biol. 3 1. 214-216. Lerondelle, C. and Poutrel, B. (1984) Characteristics of non clinical mammary infections of goats. Ann. Rech. Vet. 15. 105-112.
378
C. Vernozy Rozand et al. / Int. J. Food Microbiology 30 (19%) 373-378
Orden, J.A., Goyache, J., Hemandez, J., Domenech, A., Suarez, G. and Gomez-Lucia, E. (1992) Production of staphylococcal enterotoxins and TSST 1 by coagulase negative staphyiocoeci isolated from ruminant mastitis. J. Vet. Med. 3. 39, 144-148. Perrin-Coullioud, I., Martel, J.L., Brouillet, P. and Fedida, M. (1991) Identificatiop et sensibilite aux antibiotiques des diverses esp&es de staphylocoques asso&& a des mammites bovines inapparentes et subcliniques. Revue Med. Vet. 142, 39-47. Petersen, K.E. (1981) Cell content in goat’s milk. Acta Vet. Stand. 22, 226-237. Poutrel, B. (1984) Udder infection of goats by coagulase negative staphylococci. Vet. Microbial. 9, 131-137. Santos, E.C. and Genigeorgis, C. (1981) Survival and growth of Staphylococcus aureus in commercially manufactured Brazilian Minas cheese. J. Food Protect. 44, 177-183. Schleifer, K.H. and Kloos, W.E. (1975) A simple test system for the separation of Staphylococci from Micrococci. J. Chn. Microbial. 1, 337-338. Smith, M.C. and Roguinsky, M. (1977) Mastitis and other diseases of the goat’s udder. J.A.M.V.A. 171, 1241-1248. Stadhouders, J., Cordes, M.M.O. and Schouwenburg-Van Foeken, A.W.J. (1978) The effect of manufacturing conditions on the development of staphylococci in cheese. Their inhibition by starter bacteria. Neth. Milk Dairy J. 32, 193-203. Tatini, S.R. (1973) Influence of food environments on growth of Staphylococcus aweus and.production of various enterotoxins. J. Milk Food Technol. 36, 559-563. Valle, J., Gomez-Lucia, E., Piriz, S., Goyache, J., Orden, J.A. and Vadillo, S. (1990) Enterotoxin production by staphylococci isolated from healthy goats. Appl. Env. Microbial. 56, 1323-1326. Valle, J., Piriz, S. and Vadillo, S. (1991) Staphylococci isolated from healthy goats. J. Vet. Med. B. 38, 81-89. Vuillemin, N., Dupeyron, C., Tabone, L. and Lelvan, G. (1985) Genre Micrococcus. Evolution de la taxonomie et identification. Rev. Inst. Pasteur Lyon 18, 279-299.
Journal of
Food Microbiology 30 (1996) 373-378
Short communication
Identification of micrococcaceae isolated from goat’s milk and cheese in the Poitou-Charentes region C. Vernozy Rozanda,*, C. Mazuy”, G. Perrinb, F. Haond”, M. Bes”, Y. Brun”, J. Fleurette” “Unitt de Microbiologic, .kpidkmiologie Moltkulaire, Bourgelat, B.P. 83, F-69280 “Station Rkgionale Caprine ‘Centre National de REfGence des
l&ColeNationale VSrinaire de Lyon, I avenue Marcy l’l?toile, France de Niort, Niort, France Staphylocoques, Lyon, France
Received 30 November 1994; revised 1 July 1995; accepted 26 July 1995
Abstract
One hundred and ninety strains of coagulase-negative staphylococci were isolated from goat’s milk, whey and cheese at various stages of manufacture. Sixteen different coagulase negative Staphylococci (CNS) species were recovered, 3 of which were predominant: Staphylococcus simulans, Staphylococcus epidermidis and Staphylococcus xylosus.
The prevalent species were recovered at least at two different stages of cheese manufacturing, suggesting a better adaptation to the environment. After 15 days of ripening, the cheeses showed lower counts of Micrococcaceae. Keywords: Coagulase-negative
* Corresponding
staphylococci;
author. Telephone:
Milk; Cheese; Goat
+ 33 78872553; fax: + 33 78872554.
0168-1605/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved PII SO168-1605(96)00953-l
314
C. Vernozy Rozand et al. / ht. J. Food Microbiology 30 (1996) 373-378
1. Introductiml Most goat’s milk cheeses in France are produced in the Poitou-Charentes region. Bacteriological standards have been established for the manufacture of goat’s raw milk cheese including Staphylococcus aureus counts of less than 100 CFU per gm of cheese. Coagulase-negative staphylococci pose no public health risk and are not mentioned in the regulations. However, enterotoxigenicity of coagulase negative staphylococci isolated from goat’s milk has been reported (Valle et al., 1990; Orden et al., 1992). Coagulase-negative staphylococci have often been isolated from goat’s milk, with or without association of mastitis (Smith and Roguinsky, 1977; Petersen, 1981; Lerondelle and Pcnttrel, 1984; Poutrel, 1984; De Buyser et al., 1987; Harvey and Gilmour, 1985; B&Ii-Madani et al., 1992). The object of this study was to’ identify the dominant species of coagulase-negative staphylococci in goat’s milk cheese and investigate the possible differences in the distribution of Micrococcaceae species in milk, whey and cheese.
2. Materials and methods
2.1. Samp Iing Eighteen batches of semi-processed raw goat-milk cheeses were investigated in the Poitou-Charentes region. Samples were obtained from each of the following steps of processing: the milk used for cheese making; the curds of the day of milk curdling (cheese day 0 = LC DO); whey at curdling; cheeses at 7 days after curdling (LC D7) and 15 days after curdling (LC D15). Twenty-two processed cheeses sampled 15 days after curdling, corresponding to 22 different cheese makings, were also analysed. 2.2. Bacteriological analyses 2.2.1. Isolation of strains
Twenty-five ,ul of milk or whey were inoculated by streaking onto Staphylococcus Selective media No. 110 act to CHAPMAN (ref 5469, Merck, Darmstadt, Germany). Ten grams of cheese surface and interior were homogenized with 90 ml tryptone salt (tryptone 1,0 g, NaCl 8,5 g, HZ0 1 000 ml); 0.1 ml were surface spread on the agar medium. The plates were incubated for 72 h at 37°C. Subculturing onto trypto-casein soya agar (ref 64554, Sanofi Diagnostics Pasteur, Marnes la Coquette, France) was carried out for each type of colony encountered. Only pure cultures of Gram-positive and catalase-positive cocci were retained for identification as described below. 2.2.2. IdentiJications
Three tests were used to differentiate Micrococci and Staphylococci: (i) acid production from glycerol (Schleifer and K.loos (1975)) and Brun and Bes (1990)), on
C. Vernozy Rozand et al. /ht.
J. Food Microbiology 30 (1996) 373-378
315
Bacto purple agar (ref 0228-17-7, Difco, Detroit, Michigan, USA) containing 1% glycerol; (ii) susceptibility to lysozyme (Schleifer and Kloos, 1975) using MuellerHinton medium (ref 51075, bioMCrieux, Marcy l’Etoile, France) to which a drop of 400 pgg/ml lysozyme solution (ref L.6876, Sigma chemical, CO, PO box, 14508 St Louis, MO 63178 USA) was added; (iii) and susceptibility to nitrofurantoin (Hebert and Caillet, 1983) examined on Mueller-Hinton medium (bioMCrieux) with discs contained 300 rug of nitrofurantoin (ref 68678, Sanofi Diagnostics Pasteur). For identification of isolates to species level, the following tests were carried out: (i) coagulase using rabbit plasma (bioMerieux), according to the tube method of Vuillemin et al. (1985); (ii) the Staphylase test@ (ref DR 595A, Oxoid, Unipath limited, Wade Road, Basingstoke, Hampshire, RG24 8PW, England); (iii) novobiocin susceptibility using discs containing 5 pg novobiocin (ref 56350, Sanofi Diagnostics Pasteur, Marnes la Coquette, France), according to the technique of Almeida and Jorgensen (1982) and (iv) the ID 32 STAPH system (ref 32500, bioMCrieux, Marcy l’Etoile, France) including 26 substrates.
3. Results and discussion The colonies of Gram-positive and catalase-positive cocci observed varied as follows. For the milk samples examined, five showed only one type of colony, 11 revealed 2-3 different types of colonies and two revealed five different types of colonies. For nine of the 18 whey samples examined, Micrococcuceae were not detected; three samples revealed only one type of colony, five showed two different types of colonies and one showed three different types of colonies. On day 0 and 7, the cheeses contained two to four different types of colonies, whereas on day 15, only one colony type was seen. Of the 233 strains isolated, 190 were coagulase-negative staphylococci, 22 were coagulase positive, and 21 were micrococci (Table 1). The coagulase-positive Staphylococci all belonged to the S. aureus. Three of the 16 different coagulase negative staphylococci species detected appeared predominant (Table 2) i.e. S. simulans (51 strains); S. epidermidis (31 strains) and S. xylosus (20 strains). Table 1
C.N.S.b
C.P.S.’ Micrococcus spp
Milk (18)
Whey (IS)”
Cheese (76)”
Total (112)”
39 3
18 1
133 18
190 22
5
2
14
21
“No. of samples. %Z.N.S., coagulase-negative staphylococci. ‘C.P.S., coagulase-positive staphylococci.
376
C. Vernozy Rozand et al. 1 Int. J. Food Microbiology
30 (19%)
373-378
Table 2
Species
Milk
Whey
C* Day 0
C* Day 7
C* Day15
Total
1
1 3 0 1 17 0 1 0 0 2 0 0 1 16 2
3 2 2 18
4 1 50
0 0 0 1 2 2 0 0 0 0 3 1 0 10 0 3 4 8 34
0 5 0 0 4 1 0 1 0 1 1 0 0 22 3 1 3 7 49
2 10 1 2 31 4 1 1 7 6 9 1 1 51 6 20 16 21 190
CNS” S. auricularis S. capitis S. chromogenes S. cohnii S. epidermidis S. equorum S. gallinarum S. hominis S. lentus S. lugdunensis S. saprophyticus S. sciuri S. schleiferi S. simulans S. warneri s. xylosus S. xylosus/S. equorum
0
Unidentifed Staphylococcus Total CNS
1 2 0 0 7 0 0 0 I 3 0 0 0 1 0 12 3 3 39
Staphylococcus
3
8
0
10
22
0
0 0 1 0 2 3
0 2 2 0 1 5
1 2 0 0 3 6
1 5 4 2 9 21
aureus
Micrococcus M. nishinomiyaensis h4. roseus M. lylae M. varians unidentified Micrococcus
Total Micrococcus C*, lactic cheese. CNS**, coagulase-negative
1 1 0 3 5
0
1 0 1 1 0 0 0 0 5 0 0 2
1
staphylococci.
A further 16 strains in the S.xylosus/S.equorum group were isolated. Twenty-one coagulase negative staphylococci were unidentifiable. Staphylococcus simulans was identified in 16 different batches of cheese manufacturing; in seven of them, it was detected at two different stages and in seven others at three different stages of the cheese manufacturing. (results not shown). Strains of S. xylosus, S. equorum and S. xylosuslequorum were recovered from 15 batches; in six of them at two different stages of manufacture; in six others at three different stages and two others at four different stages (results not shown). Staphylococcus epidermidis were found in 15 batches; in three of them at two different stages of manufacture; in five at three other different stages and one at four different stages. The other coagulase-negative staphylococci identified were detected mostly at only one stage of manufacture (results not shown).
C. Vemozy Rozand et al. /ht.
J. Food Microbiology 30 (1996) 373-378
311
During the ripening, dry matter and pH of the cheeses varied from 20.3% to 44.2% and from 4.43% to 4.49%, respectively (unpublished results). The results obtained are similar to those found by Poutrel (1984), De Buyser et al. (1987) and Harvey and Gilmour (1988). No S. cuprae were detected during the present study, although this species had been recovered by the authors just mentioned above and by Bedidi-Madani et al. (1992) and Valle et al. (1991). This diverging result may be explained by the use of a selective medium that did not allow the recovery of S. caprae. Eleven percent of the coagulase-negative staphylococci could not be identified by the identification tests used. This percentage is close to that reported in other studies of goat’s milk (Poutrel, 1984; Perrin-Coullioud et al., 1991; Deinhoffer and Pernthaner, 1993). The predominant species, S. simulans, S. epidermidis and S. xylosus, were recovered at different stages of cheese manufacture indicating that they are welladapted to the cheese environment, i.e. pH, water activity, NaCl and nutrients (Tatini, 1973, Stadhouders et al., 1978, Santos and Genigeorgis, 1981).
Acknowledgements This work was supported by a grant’ from the Ministry of Agriculture and Fisheries and also by funds from bioMCrieux.The authors wish to thank Sylvie Ray-Gueniot for her contribution to this study.
References Almeida, R.F. and Jorgensen, J.M. (1982) Use of Mueller-Hinton agar to determine novobiocin susceptibility of coagulase negative staphylococci. J. Clin. Microbial. 16, 1155-l 156. Bedidi-Madani, N., Richard, Y., Borges, E. and Lerondelle, C. (1992) Identification et sensibilite aux antibiotiques des staphylocoques coagulase negative isoles de lait de chevre. Revue Med. Vet. 143, 539-545. Brun, Y. and Bes, M. (1990) Methodes diagnostiques des staphylocoques coagulase-ntgatifs. Med. Mal. Inf. Tome 2, Hors s&e Mars, 16-23. De Buyser, M.L., Dilasser, F., Hummel, R. and Bergdoll, M.S. (1987) Enterotoxin and toxic-shock syndrome toxin 1 production by staphylococci isolated from goats-milk. Int. J. Food Microbial. 5, 301-309. Deinhoffer, M. and Pernthaner, A. (1993) Differentiation of staphylococci from ewe and goat milk samples. Dtsch. tierlrztl. Wschr. 100, 234-236. Harvey, J. and Gilmour, A. (1985) Application of current methods for isolation and identification of staphylococci in raw bovine milk. J. Appl. Bacterial. 59, 2077221. Harvey, J. and Gilmour, A. (1988) Isolation and characterisation of staphylococci from goats milk produced in Northern Ireland. Lett. Appl. Microbial. 7, 79982. Hebert, J.P. and Caillet, R. (1983) Differentiation entre Microcoques et Staphylocoques par l’etude de la sensibilite a la nitrofurantome (N(SNitro-2furfurylidene-lamino-(hydrantoi’ne)). Pathol. Biol. 3 1. 214-216. Lerondelle, C. and Poutrel, B. (1984) Characteristics of non clinical mammary infections of goats. Ann. Rech. Vet. 15. 105-112.
378
C. Vernozy Rozand et al. / Int. J. Food Microbiology 30 (19%) 373-378
Orden, J.A., Goyache, J., Hemandez, J., Domenech, A., Suarez, G. and Gomez-Lucia, E. (1992) Production of staphylococcal enterotoxins and TSST 1 by coagulase negative staphyiocoeci isolated from ruminant mastitis. J. Vet. Med. 3. 39, 144-148. Perrin-Coullioud, I., Martel, J.L., Brouillet, P. and Fedida, M. (1991) Identificatiop et sensibilite aux antibiotiques des diverses esp&es de staphylocoques asso&& a des mammites bovines inapparentes et subcliniques. Revue Med. Vet. 142, 39-47. Petersen, K.E. (1981) Cell content in goat’s milk. Acta Vet. Stand. 22, 226-237. Poutrel, B. (1984) Udder infection of goats by coagulase negative staphylococci. Vet. Microbial. 9, 131-137. Santos, E.C. and Genigeorgis, C. (1981) Survival and growth of Staphylococcus aureus in commercially manufactured Brazilian Minas cheese. J. Food Protect. 44, 177-183. Schleifer, K.H. and Kloos, W.E. (1975) A simple test system for the separation of Staphylococci from Micrococci. J. Chn. Microbial. 1, 337-338. Smith, M.C. and Roguinsky, M. (1977) Mastitis and other diseases of the goat’s udder. J.A.M.V.A. 171, 1241-1248. Stadhouders, J., Cordes, M.M.O. and Schouwenburg-Van Foeken, A.W.J. (1978) The effect of manufacturing conditions on the development of staphylococci in cheese. Their inhibition by starter bacteria. Neth. Milk Dairy J. 32, 193-203. Tatini, S.R. (1973) Influence of food environments on growth of Staphylococcus aweus and.production of various enterotoxins. J. Milk Food Technol. 36, 559-563. Valle, J., Gomez-Lucia, E., Piriz, S., Goyache, J., Orden, J.A. and Vadillo, S. (1990) Enterotoxin production by staphylococci isolated from healthy goats. Appl. Env. Microbial. 56, 1323-1326. Valle, J., Piriz, S. and Vadillo, S. (1991) Staphylococci isolated from healthy goats. J. Vet. Med. B. 38, 81-89. Vuillemin, N., Dupeyron, C., Tabone, L. and Lelvan, G. (1985) Genre Micrococcus. Evolution de la taxonomie et identification. Rev. Inst. Pasteur Lyon 18, 279-299.