The Incidence of Listeria Monocytogenis in Pasteurized and Unpasteurized (Raw) Milk in Two Districts of Albania During a Period of 3 Years (2006–2008)

Abstract

ISEE-0429 Abstract: Listeriosis, a bacterial infection caused by Listeria Monocytogenes, is prevalent in newborns and immunocompromised adults, particularly in pregnant women as approximately one-third of Listeriosis cases occur during pregnancy. The bacteria are generally resistant to common food preservation methods. This study presents the first known case of Listeria Monocytogenes detection in Albania. The study was conducted on the two largest dairy producing districts by periodically (3 years, 2006–2008) analyzing 240 milk samples, of which 168 unpasteurized (raw) milk samples from tanker trucks and 72 pasteurized bottled-milk samples. The isolation and identification of Listeria monocytogenes in milk samples was according to the ISO 11290–1 method. All pasteurized bottling milk samples (72) tested negative for L. monocytogenes. From the 168 unpasteurized (raw) milk samples, 22% (37 samples) tested positive for L. monocytogenes; and 78% (131 samples) tested negative. The number of bacteria in the positive samples was based on the recommended (low) level of 100 cfu/mL. From the 37 positive samples; 2 samples contained 10 cfu/ml, under the recommended level, 28 samples contained 100 cfu/ml on the recommended level, and 7 samples contained 1000 cfu/ml, much over the recommended level. The biochemical test of positive samples identified three stereotypes of L. monocytogenes. In conclusion, pasteurization provides an effective method for short-term milk preservation, whereas the incidence of L. monocytogenes in unpasteurized (raw) milk is possibly the result of poor animal health and lack of hygiene in animal farms. The results and conclusions were used in recommending the improvement of hygiene in animal farms, periodic control of animal health and the improvement of existing legislation to the Ministry of Health and to the Ministry of the Agriculture.