A Fifteen-Year Report of Serotype Distribution and Antimicrobial Resistance of Salmonella in the Philippines

Main Article Content

Sonia Sia
Marietta Lagrada
Agnettah Olorosa
Marilyn Limas
Manuel Jamoralin Jr.
Polle Krystie Macaranas
June Gayeta
Melissa Ana Masim
Ferissa Buensalida Ablola
Celia Carlos


Background. Salmonella enterica ser. Typhi and Salmonella enterica ser. Paratyphi are agents of typhoid fever, a severe systemic disease, which remains to be a public health concern in the Philippines. Infection due to non-typhoidal Salmonella (NTS), on the other hand, most often results in a self-limiting acute gastroenteritis but may result in invasive disease in some cases.  There is scarcity of information on the Salmonella serotypes in the Philippines which limits understanding of the distribution, transmission and antimicrobial resistance of these bacteria.

Objective. This study describes the serotype distribution and antimicrobial resistance of Salmonella in the Philippines over a 15-year period.

Methodolgy. Salmonella isolates were collected through the Philippine Department of Health-Antimicrobial Resistance Surveillance Program (DOH-ARSP) from January 1, 2004 to December 31, 2018. The isolates were serotyped using Sven Gard method for slide agglutination using antigens from Denka Seiken (Japan), and S and A serotest (Thailand). Antigenic formula obtained were classified according to White-Kauffmann-LeMinor scheme. Antimicrobial susceptibility testing for ampicillin, ceftriaxone, cefotaxime, chloramphenicol, ciprofloxacin, and trimethoprim-sulfamethoxazole, were performed using both automated and conventional methods (Kirby Bauer disk diffusion and gradient diffusion method). Antimicrobial susceptibility results were interpreted using Clinical and Laboratory Standards Institute (CLSI) 2018 interpretive criteria (M100Ed28E).

Results. A total of 2,387 isolates were collected from human specimens during the 15-year study period. There were 69 serotypes of Salmonella identified with the most common being Salmonella enterica ser. Typhi: n=1895 (79.39%), Salmonella enterica ser. Enteritidis: n=182 (7.62%), Salmonella enterica ser. Typhimurium: n=87 (3.64%), Salmonella enterica ser.  Weltevreden: n=24 (1.00%), Salmonella enterica ser. Paratyphi A: n=17 (0.71%), Salmonella enterica ser. Stanley: n=17 (0.71%), Salmonella  enterica ser. Anatum: n=13 (0.54%), Salmonella enterica ser. Heidelberg: n=12 (0.50%), Salmonella enterica ser. Choleraesuis var. Kunzendorf: n=9 (0.38%). The multidrug resistant Salmonella serotypes reported in this study were mostly resistant to ampicillin, cefotaxime, ciprofloxacin combinations.

Conclusion. This present study showed that prevailing Salmonella serotypes in the Philippines were similar with Salmonella serotypes reported from other Asian countries. Typhoidal isolates were high among 6-17 years old and were mostly from males. The antimicrobial resistance rates for typhoidal Salmonella isolates to ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, ciprofloxacin, ceftriaxone and cefotaxime were lower compared with the antimicrobial resistance rates for non-typhoidal Salmonella isolates. Multidrug resistance for both Salmonella Typhi and NTS were relatively low. Continued and enhanced surveillance is needed to monitor the rising levels of antimicrobial resistance, determine risk factors and exposures associated with Salmonella Typhi and NTS infection to guide prevention and control measures.

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How to Cite
Sia, S., Lagrada, M., Olorosa, A., Limas, M., Jamoralin Jr., M., Macaranas, P. K., Gayeta, J., Masim, M. A., Ablola, F. B., & Carlos, C. (2020). A Fifteen-Year Report of Serotype Distribution and Antimicrobial Resistance of Salmonella in the Philippines. Philippine Journal of Pathology, 5(1). Retrieved from https://philippinejournalofpathology.org/index.php/PJP/article/view/169
Original Articles
Author Biographies

Sonia Sia, Research Institute for Tropical Medicine-Department of Health, Philippines

Medical Specialist IV

Head, Antimicrobial Surveillance Reference Laboratory

Marietta Lagrada, Research Institute for Tropical Medicine-Department of Health, Philippines

Medical Technologist V

Laboratory Supervisor, Antimicrobial Resistance Surveillance Reference Laboratory

Agnettah Olorosa, Research Institute for Tropical Medicine-Department of Health, Philippines

Medical Technologist IV, Laboratory Technical Staff

Antimicrobial Resistance Surveillance Reference Laboratory

Marilyn Limas, Research Institute for Tropical Medicine-Department of Health, Philippines

Senior Science ResearchSpecialist, Laboratory Technical Staff

Antimicrobial Resistance Surveillance Reference Laboratory

Manuel Jamoralin Jr., Research Institute for Tropical Medicine-Department of Health, Philippines

Senior Science Research Specialist, Laboratory Technical Staff

Antimicrobial Resistance Surveillance Reference Laboratory

Polle Krystie Macaranas, Research Institute for Tropical Medicine-Department of Health, Philippines

Senior Science Research Specialist, Laboratory Technical Staff

Antimicrobial Resistance Surveillance Reference Laboratory

June Gayeta, Research Institute for Tropical Medicine-Department of Health, Philippines

Senior Science Research Specialist, Laboratory Technical Staff, Data Manager

Antimicrobial Resistance Surveillance Reference Laboratory

Melissa Ana Masim, Research Institute for Tropical Medicine-Department of Health, Philippines

Science Research Specialist II, Data Management Officer

Antimicrobial Resistance Surveillance Reference Laboratory

Celia Carlos, Research Institute for Tropical Medicine - Department of Health, Philippines

Chair, Antimicrobial Resistance Surveillance Program

Antimicrobial Resistance Surveillance Reference Laboratory


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