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Molecular epidemiology of human and animal ecovariants of Escherichia coli from different regions of Nigeria were studied using their antibiotic susceptibility patterns, plasmid profile and pulsed-field gel electrophoresis (PFGE). E. coli was isolated using eosin methylene blue agar (EMB) and identified by conventional microbiological technique. The isolates were tested against 14 antibiotics using the disc diffusion method. PFGE was performed using XbaI as restriction enzyme according to pulse net protocol. Overall, 42 different antibiotics resistance clusters were observed, with each isolate showing resistance to at least four or more drugs tested. Fingerprinting of 140 isolates by PFGE technique and subsequent cluster analysis revealed a diverse E. coli population belonging to 47 distinct subtypes. Cluster analysis of the 120 KB plasmid bearing isolates indicated that these isolates belonged to one unique clonal group with ≥80% genetic similarity to each other, their animal or human origin, geographical distribution and clinical or non-clinical source notwithstanding. The sharing of drug resistant strains between human and animal population has shown that identical clones are circulating among human and animal population in the study area.

The effect of neuraminidase on synaptic transmission was studied at cholinergic and noncholinergic contacts in the buccal and cerebral ganglion of Ap]lysia. The amplitudes of monosynaptic unitary postsynaptic potentials generated by intracellular stimulation of identified presynaptic neurones were measured as indication for the efficacy of synaptic transmission. Neuraminidase was either intrasomatically injected into a presynaptic neurone, or the whole ganglion was incubated with the enzyme. Intrasomatic injection of the enzyme resulted in complete failure of synaptic transmission. This effect occurred independently of the transmitter used. The synaptic failure was presynaptic in origin. The biophysical characteristics of an injected neurone, particularly the amplitude and propagation of its action potential, did not appear to be affected by neuraminidase. Synaptic transmission and biophysical membrane properties were unaffected by extracellular neuraminidase. We conclude that the synaptic blockade is due to the enzyme's action inside the presynaptic nerve ending. It seems most likely that neuraminidase cleaves sialic-acid-containing-compounds associated with the nerve terminal surface membrane, probably thus causing failure of transmitter release.

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