Human Salmonella Isolates, 2012

Saturday 29th July 2017


Summary

There were 1106 human Salmonella isolates confirmed in 2012 (2011 n= 1095). S. Typhimurium phage type RDNC-May 06 remained the predominant serotype, representing 6.6% of total isolates (7% 2011). Several Salmonella serotypes showed an increase this year in comparison with 2011 with the most significant increase observed in S. Montevideo (0.1% in 2011 to 2.4% in 2012) and S. Typhimurium phage type 108/170 (0.3% in 2011 to 1.5% in 2011).

Salmonella Enteritidis phage type 9a/11: Further typing was performed on isolates previously confirmed as Salmonella Enteritidis phage type 9a. The typing results revealed that some isolates previously reported as S.  Enteritidis phage type 9a were in fact phage type 11.

Significant Outbreaks and/or Clusters:

Salmonella Typhimurium phage type 23:  A cluster of 13 cases was detected in the Auckland region during the months of January-March . PFGE analysis was performed on human and bovine isolates.  The bovine (Waikato) isolates had 3 distinct PFGE profiles, one of which was indistinguishable from the human cases (Auckland). This profile was also shown to be present in 2009, both in bovine (Waikato) and human isolates (Auckland region). No common source was identified.

Salmonella Typhimurium phage type 160: A cluster of 4 cases was detected in the Otago-Southland regions during the month of January. Cases were aged between 73-84 years old. No common source was identified.

Salmonella Saintpaul:
·    A cluster of 4 cases was detected in the Otago region during the month of January. This serotype is common in the South Island, i.e. between 74-80% of the S. Saintpaul isolates confirmed in the last couple of years were from the South Island.
·    An increase in Salmonella Saintpaul was also noticed in the South Island during the month of March. Three isolates of S. Saintpaul were also confirmed from reptile (http://www.surv.esr.cri.nz/enteric_reference/nonhuman_salmonella.php?we_objectID=2970) during that month.

Salmonella Infantis: An increase in Salmonella Infantis was noticed in the Wellington-Hutt region where 5 cases were confirmed during the month of February. Only one case was confirmed in the Wellington-Hutt region during the same period last year.

Salmonella Typhimurium phage type 193: Four cases were confirmed in the Waikato region during the month of April. The isolates were sent to the Antibiotic Reference Laboratory at ESR for susceptibility testing as overseas this phage type has been associated with multiple antibiotic resistance. The four Waikato isolates were fully susceptible to all antibiotics tested.
 
Salmonella Typhimurium phage type 197: This phage type was first isolated in New Zealand in 2005 from a case who had recently travelled overseas. Out of the 6 cases which have been confirmed since 2005, 4 have been from the Auckland region. An additional 3 cases were confirmed during the month of April from the Auckland region.

National cluster of Salmonellosis linked to imported contaminated tahini
Pulsed-Field Gel Electrophoresis (PFGE) typing was performed on case isolates associated with this outbreak , of which 3 Salmonella serotypes were identified. 17 cases have been microbiologically linked to imported contaminated tahini

S. Montevideo
·    17 cases confirmed - 12 with an indistinguishable PFGE “cluster” profile. The outbreak PFGE profile was indistinguishable from the Salmonella Montevideo isolated from unopened tubs of tahini (sesame seed paste) sourced from the warehouse of the Auckland distributor.
·    Cases were reported from the following DHBs: Bay of Plenty, Waikato, Auckland, Northland, Waitemata and Hawke’s Bay.
·    Interviews with cases using hypothesis generating questionnaires established that Middle Eastern food had been consumed prior to becoming ill.
·    Six non-human isolates of S. Montevideo were confirmed from meat/bone meal in March 2012 and one from bovine in February 2012.
·    Molecular typing was performed on S. Montevideo human and non-human isolates and the “outbreak” PFGE profile was distinguishable from the bovine and poultry isolates that had been previously identified in NZ. This “outbreak” PFGE profile was sent to CDC for comparison. CDC had previously seen this PFGE profile which had been associated with a recent outbreak in September 2012 and for which no epidemiological  link was found.
·    The implicated product was traced forward to trade (cafes, takeaway restaurants), wholesale and retail providers. A trade withdrawal was initiated prior to confirmation of Salmonella contamination; a consumer-level recall commenced on 18/12/2012. All remaining product is on hold. Food Act Officers are following up the trade withdrawal to ensure product has been removed from sale.
·    Recall information: http://www.foodsmart.govt.nz/elibrary/consumer/gesas-tahini-recall.htm
·    Salmonella Montevideo, S. Maastricht and S. Mbandaka were isolated from unopened tubs of tahini (sesame seed paste) sourced from the warehouse of the Auckland distributor.

S. Mbandaka
·    3 cases confirmed from Auckland DHB with a PFGE profile indistinguishable from the Salmonella Mbandaka isolated from unopened tubs of tahini.
·    The PFGE profile of the S. Mbandaka isolated from tahini was distinguishable to bovine and poultry PFGE profiles that had been previously identified in NZ.

S. Maastricht
·    1 case confirmed from Auckland DHB with a PFGE profile indistinguishable from the Salmonella Maastricht isolated from unopened tubs of tahini.
·    S. Maastricht has not been identified in New Zealand previously to this outbreak.

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Human Salmonella Isolates, 2012

 

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Human Salmonella Isolates, 2012

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