Prevalence of Soil-borne Listeria monocytogenes in selected district of Punjab province, Pakistan

Abstract

Distribution of Listeria monocytogenes across Punjab province, Pakistan Listeriosis, caused by Listeria monocytogenes (Lm), has zoonotic implications and results in encephalitis, meningitis and abortions. The organism exists in the environment (soil) in abundance and thus, serves as a potential source of contamination to crops, vegetables, water and animals. We determined the genome based distribution of L. monocytogenes (hly gene) in selected districts of Punjab province, Pakistan. A total of 970 soil samples were processed independently by real-time PCR and an association between occurrences in soil was correlated to several categorical variables. The genome was detected in 17 samples (1.75%, 95 % CI: ±0.5), each originating from different location across districts under study. A more number of soil samples were detected in district Attock followed by Sheikhupura, Faisalabad, Sargodha, Sahiwal and Lahore. The odds for occurrence of Lm were more at places near water source [2.85, CI:95% (0.9256, 8.831) p=0.05] and having more than 1000 animals per village [3.32, CI:95% (1.077, 10.27) p=0.02]. The study concludes presence of Lm in the soil of study districts and, thus could be a potential source of disease in human and animal. Future studies are required to identify a causal relationship between presence of bacterium in soil to seroconversion in animal and human, and prevalent serotype across a wide geographical areas across Pakistan. Keywords: Listeria monocytogenes, Pakistan, hly gene, soil Effect of Soil chemistry on distribution of Listeria monocytogenes across Punjab province, Pakistan Comparative study was carried out to ascertain the effect of various soil physicochemical factors with the presence of Listeria monocytogenes (LM) in soil. A total of 34 soil samples (n=17 positive for LM and n=17 negative for LM) were collected from nine districts of Punjab province, Pakistan and their soil chemistry was performed respectively by following standard protocols. Various factors like pH, moisture, total soluble salts, phosphorous (P), copper (Cu), chromium(Cr), nickel (Ni), manganese (Mn), cobalt (Co), lead (Pb), cadmium (Cd), iron (Fe), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), nitrogen (N), electrical conductivity, silt, sand, clay and organic matter were studied. Upon statistical analysis significant association (P<0.05) was observed for clay and organic matter with the presence of LM in soil. Whereas other factors like silt, sand, pH, soluble salts, nitrogen, phosphorus, nickel, cadmium, copper, manganese, calcium, magnesium, lead, sodium, zinc and potassium failed to produce any significant association (P>0.05) with presence of LM in soil. Key words: Chemical factors, Listeria monocytogenes, soil, metal, Pakistan