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.