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Antibiotics in Milk from Farms
1766
J O U R N A L OF D A I R Y S C I E N C E
A n t i b i o t i c s in Milk from Farms F. J. DoA~
Department of Dairy SeiencG The Pennsylvania State University~ University Par]~ When the mammary glands of dairy cows are treated with antibiotic preparations in an effort to control or eliminate infections, the milk from such udders will contain objectionable quantities of these drugs for several milkings (1, 2, 3, 10, 14). The amounts present, of course, will vary with the concentration and kind of antibiotic introduced, the carrier or vehicle employed in the preparation, the amount of milk drawn from the gland, and the time interval between treatment and milking (l, 3). The milk may appear normal in every respect to the producer but the small amounts of antibiotic or antibiotics present, even when diluted with milk from untreated cows, are very often sufficient to cause trouble in the dairy plant receiving the milk (3). They may also be sufficient to cause undesirable effects in milk consumers who are particularly sensitive to these drugs (14). Furthermore, suspicions are being aroused that products made from lnilk containing antibiotics may contain infectious organisms that are antibiotic resistant and if implanted in human tissues are difficult for physicians to treat
(6, 12). The Dairy Plant Problem Just as antibiotics will destroy or imwtivate some of the more common organisms causing mastitic infections in the udders of cows, so will they also destroy or inactivate most of the organisms used for developing acidity, flavor and curd character in cultured buttermilk, cultured cream, and a wide variety of cheese (1,3). The quality of all these products is dependent on the activity and normal functioning of the bacterial cultures used in the manufacturing processes. If the cultures do not act normally, it is either impossible to make the product at all or the product finally obtained is of poor quality and variable character (13). Such inferior dairy products, if salable, bring a h)wer 1)rice and certainly affect consumption adversely. Many dairies and cheese plants during the last ,~ to ]0 years have had m<)re difficulty than was formerly experienced in manufacturing cultured dairy products because of the failure of cultures to ripen milk. Doubtless antibiotics in the nlilk supply have n<)t been the cause of all the starter difficulties and failures experienced in this period, but there is little question but that they have been responsible for a significant proportion. The only process used in the making of cultured dairy products and eheeses that might be expected to inactivate or destroy antibiotics in milk is that of pasteurization. Several
investigators (-i, 7, 8, 9) have shown, however, that the antibiotics commonly used for mastitis treatment, when in milk, are not significantly affected by the usual pasteurization heat treatments. Temperatures over boiling do reduce activities from 30 to 75%, but such temperatures also tend to caramelize the milk, alter its curd qualities, and render it unfit for the products in question.
Public Health Hazard The medical literature has reported many cases of acute sensitivity to antibiotics among humans. Some people can not tolerate even very small quantities of these drugs whether they be injected by syringe or ingested by way of food. The levels of antibiotics sometimes found in milk are definitely dangerous to them. It is becoming increasingly evident that the indiscriminate use of antibiotics by humans is dangerous. Schneierson, Mt. Sinai Hospital, New York (11) states that the use of antibiotics for trivial aihuents may gradually build up a sensitivity, even in individuals who show great tolerance initially, thereby ruling out their use at a later time when a serious infection might make their employment vitally important. He further states that it is now well recognized that the residual effects of continued consumption of, or treatment with, antibiotics upsets the normal bacterial flora relationships of the body. It permits antibioticresistant organisms, previously harmless, to multiply, flourish, acquire virulence, and establish themselves as invaders. This often permits normally innocent molds to attack the umuth, rectum, vagina, and lungs, and the new infections are usually much harder to treat than the infection which invited the use of an antibiotic in the first place. Another angle to the public health aspect of antibiotic residues in milk is that dairy foods made from such milk amy contain unusual antibiotic-resistant strains of infectious bacteria capable of causing illness in humans. This suspicion was voiced in a Canadian note recently published in the Journal of the American Medical Association (6). I t was stated that when micrococei and streptococci, resistant to antibiotics, are encountered in patients with no history of hospitalization or antibiotic therapy, the cause may be found in the consumption of foods that contain such antibioticresistant bacteria. I n support of this idea the findings of Thatcher and Simon were mentioned. These workers (12) examined 100 specimens of cheese obtained from the Canadian retail market. Sixty-seven per cent of the streptococci isolated and 15% of the mieroceocci were
OUR INDUSTRY TODAY
f o u n d to be resistant to penicillin. The study. revealed thtlt the organisms isolated were most ~ f t e n resistant to penicillin and dihydrostreptomyein, the two drugs most f r e q u e n t l y used in treating cows for mastitis. The F e d e r a l F o o d and D r u g Administration, in a statement of policy issued F e b r u a r y 18, 1953 (5), recognized the health hazard of antibiotics in foods and the possibility that their eonsmnption may cause sensitization of con.sumers and may also result in the emergence of strains of pathogenic organisms resistant to antibiotics. The F.D.A. statement asserts that the direct or indirect addition of such drugs to foods nmy be deemed an adulteration under the food laws. The presence of antibiotics in nfilk coming f r o m the f a r m is therefore illegal m~d is classified as an adulteration. Prevalence
of A n t i b i o t i c s i n M i l k
Increasing amounts of antibiotics are being used in the treatment of mastitis, dosages are larger, and m a n y milk producers fail to use the necessary care in keeping the milk f r o m treated udders off the market until the antibiotic disappears. This requires at least six milkings f o r the more commonly used drugs (l~f). There is also the possibility that antibiotics m a y be directly added to milk in an effort to reduce the number of viable bacteria. That the problem is becoming more acute seenls evident f'ronl an ]?.D.A. survey completed early in 1955. This indicated that 11.6% of 474 smuples of milk, collected nation-wide, contained measurable mnounts of penicillin (1~). A survey made a year earlier found only 3.2% of 94 samples positive. I t lnight be emphasiz, ed that of the 474 samples in the latest survey only 22 were raw milk and of these only one contained an antibiotic. This might be taken to indicate that the vendors of raw milk are much more careful with the milk leaving the f a r m than are those who ship to pasteurizing plants.
pen, nfilk and dairy products might receive a blast of unfavorable comment and criticism that would undo all the favorable publicity on food value that has been built up over the years. The time seems ripe f o r d a i r y producers~ dealers, and m a n u f a c t u r e r s to take a long, hard h)ok at the antibiotic problem with the idea of reversing present trends. Unless this is done, there is an increasing likelihood that the industry may be p u t in an embarrassing and damaging position in the eyes of the public. REFERENCES (1) BELL, W. B., FLORA, C. C., REAVE,S, F. M., AND' ]:~OLDA~VAY,C. W. Aureomycin Concentration in Milk Following Intra Mammary Infusion and Its Effect on Starter Activity. J. Dairy Sei., 34: 675. 1951. (2) t~aYAN, C. S. Problems Created for the Dairy Industry by Antibiotic Mastltis Treatment. Mich. Agr. Expt. Sta., Quart. BMI., 33: 223. 1951. (3) CLAYBAUGt{,O. A., AND NELSON, F. E. The
(4) (5) (6) (7)
(8) (9)
(10)
Threat to the Dairy Industry The promiscuous and ill-considered use of antibiotics in t r e a t i n g mastitis in d a i r y cows, which seems on the increase, coupled with carelessness in keeping milk from such cows off the market, m a y be looked upon as a serious t h r e a t to the d a i r y industry. First, because antibiotics in the milk supply make high quality cultured dairy products impossible of a t t a i n m e n t m~d m a y eventually seriously affect consmnption of these products. Second, because the increasing incidence and concentrat i o n of antibiotics in milk and dairy products nmy create a health hazard which will become more generally recognized. I f this should hap-
1767
(11)
(12)
(13)
(14)
Effect of Antibiotics in Milk: A Review. J. Milk and Food Teeh~ol. 14: 155. 1951. DOAN, F. J. Antibiotics in Milk. Milk Dealer, 40 (1): 102. 1950. Federal Register 18 F. R. 1077. Feb. 25, 1952. Foreign Notes (Canada). J. Am. Med. Assoc., 159: 1788. 1955. HOOD, E. G., AND KATZNELSON,H. TiLe Effect of Penicillin on Acid Producing Ability of Starters. Can. Dairy Ice Cream J., 28 (3): 32. 1949. HUNT~, G. J. E. The Effect of Penicillin in Milk on the Manufacture of Cheddar Cheese. J. Dairy Researck, 15: 235. 1949. I~RIENt(E., W. A. Effects on Acid Production by Lactic Starters of Various Drugs in Milk from Mastitis Treated Cows. Butter, Cheese and Dairy Products J., 41 (7): 32. 1950. RANDALL,W. A., DURBIN, C. G., WILMER., J., AND COLLINS, J. H. Antibiotics Concentration and Duration in Animal Tissue and Body Fluids. I. Blood Serum and Milk of Cows. Antibiotics Anneal 195354, Medical Encyclopedia, Inc., New York. SCHNE,IEP~SON, S. S. H'~zards of Antibiotics. Consumer Reports, 18 (4) : 162. 1953. THATCtIER, F. S., AND SII~[ON, W. The Resistance of Staphylococei and Streptococci Isolated from Cheese to Various Antibiotics. Can. J. Public Health, 46: 407. 1955. TIIO~AS, S. ]~., AND PANES, J. J. Further Studies on the Effects of Penicillin in Milk Used for the Manufacture of Cheshire Cheese. J. Soe. Dairy Technol., 9 (2): 87. 1956. WELCH, HE;NaY, JESTEII, W. ~., AND BuR'rON, M. Antibiotics in Fluid Milk. Antibiotics and Chemotherapy, 5 (10): 571. 1955.
J O U R N A L OF D A I R Y S C I E N C E
A n t i b i o t i c s in Milk from Farms F. J. DoA~
Department of Dairy SeiencG The Pennsylvania State University~ University Par]~ When the mammary glands of dairy cows are treated with antibiotic preparations in an effort to control or eliminate infections, the milk from such udders will contain objectionable quantities of these drugs for several milkings (1, 2, 3, 10, 14). The amounts present, of course, will vary with the concentration and kind of antibiotic introduced, the carrier or vehicle employed in the preparation, the amount of milk drawn from the gland, and the time interval between treatment and milking (l, 3). The milk may appear normal in every respect to the producer but the small amounts of antibiotic or antibiotics present, even when diluted with milk from untreated cows, are very often sufficient to cause trouble in the dairy plant receiving the milk (3). They may also be sufficient to cause undesirable effects in milk consumers who are particularly sensitive to these drugs (14). Furthermore, suspicions are being aroused that products made from lnilk containing antibiotics may contain infectious organisms that are antibiotic resistant and if implanted in human tissues are difficult for physicians to treat
(6, 12). The Dairy Plant Problem Just as antibiotics will destroy or imwtivate some of the more common organisms causing mastitic infections in the udders of cows, so will they also destroy or inactivate most of the organisms used for developing acidity, flavor and curd character in cultured buttermilk, cultured cream, and a wide variety of cheese (1,3). The quality of all these products is dependent on the activity and normal functioning of the bacterial cultures used in the manufacturing processes. If the cultures do not act normally, it is either impossible to make the product at all or the product finally obtained is of poor quality and variable character (13). Such inferior dairy products, if salable, bring a h)wer 1)rice and certainly affect consumption adversely. Many dairies and cheese plants during the last ,~ to ]0 years have had m<)re difficulty than was formerly experienced in manufacturing cultured dairy products because of the failure of cultures to ripen milk. Doubtless antibiotics in the nlilk supply have n<)t been the cause of all the starter difficulties and failures experienced in this period, but there is little question but that they have been responsible for a significant proportion. The only process used in the making of cultured dairy products and eheeses that might be expected to inactivate or destroy antibiotics in milk is that of pasteurization. Several
investigators (-i, 7, 8, 9) have shown, however, that the antibiotics commonly used for mastitis treatment, when in milk, are not significantly affected by the usual pasteurization heat treatments. Temperatures over boiling do reduce activities from 30 to 75%, but such temperatures also tend to caramelize the milk, alter its curd qualities, and render it unfit for the products in question.
Public Health Hazard The medical literature has reported many cases of acute sensitivity to antibiotics among humans. Some people can not tolerate even very small quantities of these drugs whether they be injected by syringe or ingested by way of food. The levels of antibiotics sometimes found in milk are definitely dangerous to them. It is becoming increasingly evident that the indiscriminate use of antibiotics by humans is dangerous. Schneierson, Mt. Sinai Hospital, New York (11) states that the use of antibiotics for trivial aihuents may gradually build up a sensitivity, even in individuals who show great tolerance initially, thereby ruling out their use at a later time when a serious infection might make their employment vitally important. He further states that it is now well recognized that the residual effects of continued consumption of, or treatment with, antibiotics upsets the normal bacterial flora relationships of the body. It permits antibioticresistant organisms, previously harmless, to multiply, flourish, acquire virulence, and establish themselves as invaders. This often permits normally innocent molds to attack the umuth, rectum, vagina, and lungs, and the new infections are usually much harder to treat than the infection which invited the use of an antibiotic in the first place. Another angle to the public health aspect of antibiotic residues in milk is that dairy foods made from such milk amy contain unusual antibiotic-resistant strains of infectious bacteria capable of causing illness in humans. This suspicion was voiced in a Canadian note recently published in the Journal of the American Medical Association (6). I t was stated that when micrococei and streptococci, resistant to antibiotics, are encountered in patients with no history of hospitalization or antibiotic therapy, the cause may be found in the consumption of foods that contain such antibioticresistant bacteria. I n support of this idea the findings of Thatcher and Simon were mentioned. These workers (12) examined 100 specimens of cheese obtained from the Canadian retail market. Sixty-seven per cent of the streptococci isolated and 15% of the mieroceocci were
OUR INDUSTRY TODAY
f o u n d to be resistant to penicillin. The study. revealed thtlt the organisms isolated were most ~ f t e n resistant to penicillin and dihydrostreptomyein, the two drugs most f r e q u e n t l y used in treating cows for mastitis. The F e d e r a l F o o d and D r u g Administration, in a statement of policy issued F e b r u a r y 18, 1953 (5), recognized the health hazard of antibiotics in foods and the possibility that their eonsmnption may cause sensitization of con.sumers and may also result in the emergence of strains of pathogenic organisms resistant to antibiotics. The F.D.A. statement asserts that the direct or indirect addition of such drugs to foods nmy be deemed an adulteration under the food laws. The presence of antibiotics in nfilk coming f r o m the f a r m is therefore illegal m~d is classified as an adulteration. Prevalence
of A n t i b i o t i c s i n M i l k
Increasing amounts of antibiotics are being used in the treatment of mastitis, dosages are larger, and m a n y milk producers fail to use the necessary care in keeping the milk f r o m treated udders off the market until the antibiotic disappears. This requires at least six milkings f o r the more commonly used drugs (l~f). There is also the possibility that antibiotics m a y be directly added to milk in an effort to reduce the number of viable bacteria. That the problem is becoming more acute seenls evident f'ronl an ]?.D.A. survey completed early in 1955. This indicated that 11.6% of 474 smuples of milk, collected nation-wide, contained measurable mnounts of penicillin (1~). A survey made a year earlier found only 3.2% of 94 samples positive. I t lnight be emphasiz, ed that of the 474 samples in the latest survey only 22 were raw milk and of these only one contained an antibiotic. This might be taken to indicate that the vendors of raw milk are much more careful with the milk leaving the f a r m than are those who ship to pasteurizing plants.
pen, nfilk and dairy products might receive a blast of unfavorable comment and criticism that would undo all the favorable publicity on food value that has been built up over the years. The time seems ripe f o r d a i r y producers~ dealers, and m a n u f a c t u r e r s to take a long, hard h)ok at the antibiotic problem with the idea of reversing present trends. Unless this is done, there is an increasing likelihood that the industry may be p u t in an embarrassing and damaging position in the eyes of the public. REFERENCES (1) BELL, W. B., FLORA, C. C., REAVE,S, F. M., AND' ]:~OLDA~VAY,C. W. Aureomycin Concentration in Milk Following Intra Mammary Infusion and Its Effect on Starter Activity. J. Dairy Sei., 34: 675. 1951. (2) t~aYAN, C. S. Problems Created for the Dairy Industry by Antibiotic Mastltis Treatment. Mich. Agr. Expt. Sta., Quart. BMI., 33: 223. 1951. (3) CLAYBAUGt{,O. A., AND NELSON, F. E. The
(4) (5) (6) (7)
(8) (9)
(10)
Threat to the Dairy Industry The promiscuous and ill-considered use of antibiotics in t r e a t i n g mastitis in d a i r y cows, which seems on the increase, coupled with carelessness in keeping milk from such cows off the market, m a y be looked upon as a serious t h r e a t to the d a i r y industry. First, because antibiotics in the milk supply make high quality cultured dairy products impossible of a t t a i n m e n t m~d m a y eventually seriously affect consmnption of these products. Second, because the increasing incidence and concentrat i o n of antibiotics in milk and dairy products nmy create a health hazard which will become more generally recognized. I f this should hap-
1767
(11)
(12)
(13)
(14)
Effect of Antibiotics in Milk: A Review. J. Milk and Food Teeh~ol. 14: 155. 1951. DOAN, F. J. Antibiotics in Milk. Milk Dealer, 40 (1): 102. 1950. Federal Register 18 F. R. 1077. Feb. 25, 1952. Foreign Notes (Canada). J. Am. Med. Assoc., 159: 1788. 1955. HOOD, E. G., AND KATZNELSON,H. TiLe Effect of Penicillin on Acid Producing Ability of Starters. Can. Dairy Ice Cream J., 28 (3): 32. 1949. HUNT~, G. J. E. The Effect of Penicillin in Milk on the Manufacture of Cheddar Cheese. J. Dairy Researck, 15: 235. 1949. I~RIENt(E., W. A. Effects on Acid Production by Lactic Starters of Various Drugs in Milk from Mastitis Treated Cows. Butter, Cheese and Dairy Products J., 41 (7): 32. 1950. RANDALL,W. A., DURBIN, C. G., WILMER., J., AND COLLINS, J. H. Antibiotics Concentration and Duration in Animal Tissue and Body Fluids. I. Blood Serum and Milk of Cows. Antibiotics Anneal 195354, Medical Encyclopedia, Inc., New York. SCHNE,IEP~SON, S. S. H'~zards of Antibiotics. Consumer Reports, 18 (4) : 162. 1953. THATCtIER, F. S., AND SII~[ON, W. The Resistance of Staphylococei and Streptococci Isolated from Cheese to Various Antibiotics. Can. J. Public Health, 46: 407. 1955. TIIO~AS, S. ]~., AND PANES, J. J. Further Studies on the Effects of Penicillin in Milk Used for the Manufacture of Cheshire Cheese. J. Soe. Dairy Technol., 9 (2): 87. 1956. WELCH, HE;NaY, JESTEII, W. ~., AND BuR'rON, M. Antibiotics in Fluid Milk. Antibiotics and Chemotherapy, 5 (10): 571. 1955.