Laboratory systems research

Following on from the PFGE report of isolates to the end of 2008 (PFGE Typing of Meat
Isolates of E. coli O157:H7 in New Zealand; ESR, March 2009), this report describes the
results of PFGE analysis of an additional 55 E. coli O157:H7 isolates from meat received by ESR to 1 October 2009, and includes nine isolates associated with the
AgResearch/AsureQuality “Investigating E. coli O157:H7 False Positives” project.

From March to September 2006, 25 isolates were uploaded to the PulseNet USA E. coli O157:H7 pulsed field gel electrophoresis (PFGE) database with the XbaI:BlnI pattern EXHX01.0074:EXHA26.0569. Although this pattern is relatively common in the US database, this number of isolates suggests a potential common source outbreak. USDA-FSIS found E. coli O157:H7 isolates from two meat-processing plants with two similar XbaI:BlnI patterns (EXHX01.0074:EXHA26.0569 and EXHX01.1401:EXHA26.0569). One common link between these meat-processing plants is that both sourced some of their meat from New Zealand.

The molecular typing by PFGE has now been completed on all E. coli O157:H7 isolates
from young calves, bovine, veal, prime beef, and human cases included in the 2006 PFGE
Emergency Response typing project as well as prime beef and veal isolates submitted to
ESR up to July 24th 2008. The PulseNet Aotearoa (New Zealand) E. coli database contains
723 NZ E. coli O157:H7 isolates, including 411 human, 189 meat, 118 animal, and 4
environmental isolates.

This document reports on a recent survey for pYV-positive Y. enterocolitica (YeP+) on retail raw pork using a new rapid and sensitive method developed at ESR to both detect (presence/absence) and enumerate (by most probable number method) this pathogen.

This report details the available methods for the detection of coagulase-producing staphylococci and their enterotoxins that could be applied at various stages during cheese production from the view of their possible use by small cheese makers.

Since April 2007, a testing programme has been in place at New Zealand poultry primary
processing plants to determine the Campylobacter spp. status of birds entering primary
processing, and carcasses at the end of processing. The end of processing testing includes
rinsing of carcasses taken after the immersion chiller, plating of a rinse subsample, and
counting of Campylobacter colonies, if present.