Virulence, Antimicrobial Resistance and Biofilm Production of Escherichia coli Isolates from Healthy Broiler Chickens in Western Algeria

The aim of this study was to assess the virulence, antimicrobial resistance and biofilm production of Escherichia coli strains isolated from healthy broiler chickens in Western Algeria. E. coli strains (n = 18) were identified by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry. Susceptibility to 10 antibiotics was determined by standard methods. Virulence and extended-spectrum β-lactamase (ESBL) genes were detected by PCR. The biofilm production was evaluated by microplate assay. All the isolates were negative for the major virulence/toxin genes tested (rfbE, fliC, eaeA, stx1), except one was stx2-positive. However, all were resistant to at least three antibiotics. Ten strains were ESBL-positive. Seven carried the β-lactamase bla_TEM gene only and two co-harbored bla_TEM and bla_CTX-M-1 genes. One carried the bla_SHV gene. Among the seven strains harboring bla_TEM only, six had putative enteroaggregative genes. Two contained irp2, two contained both irp2 and astA, one contained astA and another contained aggR, astA and irp2 genes. All isolates carrying ESBL genes were non-biofilm producers, except one weak producer. The ESBL-negative isolates were moderate biofilm producers and, among them, two harbored astA, two irp2, and one aggR, astA and irp2 genes. This study highlights the spread of antimicrobial-resistant E. coli strains from healthy broiler chickens in Western Algeria.

Development of SYBR Green real-time PCR for diagnosis of fasciolosis in sheep

Fasciolosis is commonly diagnosed by microscopic detection of egg following sedimentation. However, this technique is time-consuming when a large number of samples must be processed and requires sufficient experience. Quantitative real-time PCR based on the detection of liver fluke ribosomal DNA in feces has been introduced, which is more accurate and liable to reflect the presence of flukes in hosts. This study aimed to develop an efficient molecular detection method in laboratory diagnosis. A cross-sectional study of 250 sheep was performed to detect Fasciola hepatica infections using gold standard microscopic detection, conventional PCR and real-time PCR. Both conventional and real-time PCRs targeted the internal transcribed spacer 2 (ITS-2). A composite reference standard(CRS) was used to analyze the sensitivity and specificity of three methods. Furthermore, the minimal amount of plasmid DNA detected by the real-time PCR was 1.67 pg plasmid DNA (equivalent to 1.1 × 10⁶ copies). In conclusion, a highly sensitive and specific method for fasciolosis in sheep was developed.