Assignment of serotype to Salmonella enterica isolates obtained from poultry and their environment in southern Brazil

Published on: 11/01/2016
Author/s : M. Pulido-Landinez 1,2; R. Sanchez-Ingunza 3; J. Guard 3 and V. Pinheiro do Nascimento 2. / 1 Avian Pathology Laboratory, College of Veterinary Medicine, National University of Colombia, Bogota, Colombia; 2 Avian Diagnostic and Research Center, College of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Brazil; 3 United States Department of Agriculture, Agricultural Research Service, Athens, GA, USA.

  Introduction Brazil currently ranks as the major exporter of chicken meat in the world with markets in more than 150 countries. Salmonella enterica (Salm. enterica) is one of the most important bacterial pathogens that can cause foodborne illness (Schroeder et al. 2006). It is often transmitted to people by eggs and other poultry products (Hogue et al. 1997). The Brazilian poultry industr...

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November 1, 2016
Unfortunately not all countries have the means to perform the PCR for the sero typing of Salmonella. This study shows the necessity for poultry producers to perform a survey of the epidemiological situation of Salmonella in their operations at least once yearly. The presence of Salmonella enteritidis in the chicks means that the breeders could have been affected or else can it be the strain of a LIVE SE vaccine?
A monitoring of Salmonella in the broilers can be done with the overshoes at 17 to 20 days old. But, the serotyping is EXPENSIVE. There are 2 500 salmonella strains. So, a positive culture does not mean that there is a risk of PATHOGENIC salmonella for humans. Be careful of the communication. People can be very scared just by the name of Salmonella. Remember the episode in the UK where a Minister had to resign due to a communication.
November 2, 2016

Regarding the comment of Dr. Ismet Mamode it is import to clarify some concepts.

Firstly, we should communicate that not all Salmonella serovars have the same importance for public health and we must concentrate in the control of some that are the most pathogenic and frequent in human diseases. In fact, in practice it would be impossible to eradicate all 2,500 serovars.
Secondly, modern live SE vaccines can be easily differentiated from wild SE strains using simple kits accessible to any simple bacteriological laboratory.

Thirdly, the best way to bacteriologically monitor the entrance of salmonelas is in 1-old-day chicks before they enter in the farm. Pooled samples of egg-yolk and liver with gallbladder or even meconium are the best way.

Best regards,
Dr. Horacio Raúl Terzolo

Ahmed Sayed Hamouda Ahmed Sayed Hamouda
Doctor of Veterinary Medicine
November 18, 2016
First of all thank you very much for this valuable work ,my opinion is to put international strategy to control salmonella not to eradicate salmonella we have to start typing according to the ISR and and define epidemiological map and start a vaccination program using vector vaccine.
Prof.Dr. Hamouda A.S.
Professor of Poultry Disease Cairo university Egypt
Specialist in Salmonella
November 18, 2016
Hi all, thanks for the constructive comments. In regards to the availability of PCR, used thermocyclers can be acquired at very low cost and the cost of primers is trivial. We don't even have to send ISR products out for sequencing to see that we get positive bands for Salmonella enterica subspecis I. Since the capability to conduct PCR is the basis of so many tests today, a laboratory that does not have this capability should work on acquiring it. It is used across so many disease of poultry! If a scientist is in a country where it is extremely difficult to acquire such equipment and materials, and I know there are problems beyond my imagination out there, then partnering with another country's academic or even public health institutions might be possible.

We developed the ISR method to overcome many problems associated with cost of either very expensive Luminex based equipment and the cost of antisera, Neogen picked up the basis of ISR for their "Neoseek" service, but it is not necessary to purchase Neoseek if a laboratory is comfortable with PCR. I don't think we can get serotyping of Salmonella any cheaper, because we are targeting only 1 genomic region with both forward and reverse directions required for most accuracy (2 sequencing reactions per PCR amplified product obtained from a suspect culture). There is a cost of sequencing, but it can be reduced through establishing collaborations and maximizing numbers of samples processed per 96 well plate (48 isolates X 2 sequence directions).

The biggest impact we have seen is that it is letting a lot of countries do Salmonella serotyping. Martha Pulido-Landinez further improved the technique to allow DNA to be spotted on filter paper. This means that you don't have to send living culture all packaged in a box, you can just mail a letter to a collaborator with the filter paper inside!

Please don't hesitate to contact me again.

Jean Guard, DVM, PhD
Veterinary Medical Officer
US Dept of Agriculture
US National Poultry Research Center
950 College Station Rd
Athens, GA 30605

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