Factors Associated with Testing Methods Used to Diagnose Non-typhoidal Salmonella Restricted; Files Only

Cole, Matthew (Fall 2017)

Permanent URL: https://etd.library.emory.edu/concern/etds/j6731377h?locale=en
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Abstract

Background: Since 2012, culture-independent diagnostic testing (CIDT) for non-typhoidal Salmonella has increased in Georgia (GA). The number of salmonellosis cases diagnosed by only CIDT has doubled from 186 in 2014 to 392 in 2016. CIDTs are cheap, fast, and help create better estimates for disease burden, but also carry the risk of creating false-positives and rarely send isolates for analysis by public health laboratories. Data on demographics, clinical, and exposure is collected by active surveillance of the GA Department of Public Health (GDPH) Foodborne Active Surveillance Network (FoodNet). The impact of testing method on hospitalization status and timely reporting to public health has not been assessed.

Methods: Demographic, clinical, and exposure characteristics of non-typhoidal Salmonella cases tested only by culture and CIDT were compared from 2014 – 2016. Two multivariate logistic regression models were fitted to assess the relationship between testing methods on hospitalization status and timely reporting.

Results: From 2014 – 2016, 6470 cases of salmonellosis with complete demographic information were reported to GDPH. Of these, 5765 (89%) were diagnosed by culture or reflex culture; and 705 (11%) were diagnosed only with CIDT. And 3051 (53%) patients diagnosed with culture and 162 (23%) patients diagnosed with CIDT only were hospitalized. Finally, 3175 (55%) salmonellosis cases diagnosed with culture and 461 (65%) diagnosed with CIDT only were reported to public health within seven days of symptom onset.

CIDT-diagnosed patients were more likely to be < 5 years of age (67%) while culture-tested cases tended to be white and reside outside of metro Atlanta. There were no significant differences observed in gender or ethnicity.

After adjusting for region and age, CIDTs were more likely to be sent within seven days compared to culture. Effect modification was identified by region and age and after adjustments, patients with CIDTs were less likely to be hospitalized than those cultured.

 

Conclusions: CIDT usage continues to increase in GA and benefit public health by quicker reporting time and rapid treatment for patients to avoid hospitalization. But CIDT usage also limits GDPH’s ability to conduct outbreak investigations.  GDPH should continue to monitor if CIDT usage effects the instance or investigation of foodborne disease outbreaks.

Table of Contents

Table of Contents

 

Chapter I: Literature Review…………………………………………………………………1

Chapter II: Manuscript……………………………………………………………………….8

Introduction…………………………………………………………………………..8

Methods……………………………………………………………………………..10

Results………………………………………………………………………………12

Discussion…………………………………………………………………………..14

References…………………………………………………………………………..18

Tables……………………………………………………………………………….20

Figures………………………………………………………………………………23

Appendix……………………………………………………………………………25

 

Chapter III: Summary, Public Health Implications, Possible Future Directions…………...27

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