Abstract
In Bangladesh, human sludge from dry pit latrines is commonly applied directly to agricultural lands as manure. This study was conducted to investigate the presence of antibiotic resistance, virulence factors and plasmid contents of E. coli strains isolated from sludge samples. E. coli were isolated from human feces from closed pit latrines and identified by culture method. Antibiotic susceptibility patterns of the isolates were determined by Standard Kirby-Bauer disk diffusion method. Pathogenic genes and antibiotic resistance genes of ESBL producing isolates were determined by PCR assay. Of the 34 samples tested, 76.5% contained E. coli. Of 72 E. coli isolates, 76.4% were resistant to at least one of the 12 antibiotics tested and 47.2% isolates were resistant to three or four classes of antibiotics. Around 18% isolates were extended spectrum β- lactamase producing and of them 6 were positive for blaTEM specific gene, 4 for blaCTX-M gene, 1 for blaOXA gene and 2 for both blaTEM and blaCTX-M genes. Moreover, among 72 isolates, 4.2% carried virulence genes of enterotoxigenic E. coli; two isolates were positive for st and one was positive for both st and lt genes. In addition, 59.7% of the isolates contained plasmids (range 1.4 to 140 MDa) of which 19.5% isolates contained a single plasmid and 40.2% contained multiple plasmids. The presence of pathogenic, drug resistant E. coli in human sludge necessitates a regular surveillance before using as a biofertilizer.
Highlights
In Bangladesh, human sludge from dry pit latrines is commonly applied directly to agricultural lands as manure
To test whether fecal sludge samples are positive for the presence of E. coli or not, first we performed conventional plate culture method using mTEC agar plate
Multiple colonies were selected from the positive samples based on proper match with the positive control and later sample redundancy was removed by antibiotic resistance pattern
Summary
In Bangladesh, human sludge from dry pit latrines is commonly applied directly to agricultural lands as manure. Land application and or disposal of both human and cattle wastes of fecal origin is becoming a routine procedure in many areas of the world [1,2] The use of such wastes in agricultural farming might spread antibiotic resistant bacteria to humans if the wastes are contaminated, as several research have proven [3,4]. Farmers of low income countries tend to use human feces as fertilizer due to availability and lower cost [9]. They face the greatest risk of suffering from diseases if such fecal sludge is not treated well before applying to the field. Due to rain, flood and poor sanitation, ponds and rivers become contaminated from
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