1. Evaluation of an Electricity-free, Culture-based Approach for Detecting Typhoidal Salmonella Bacteremia during Enteric Fever in a High Burden, Resource-limited Setting.
- Author
-
Andrews, Jason R., Prajapati, Krishna G., Eypper, Elizabeth, Shrestha, Poojan, Shakya, Mila, Pathak, Kamal R., Joshi, Niva, Tiwari, Priyanka, Risal, Manisha, Koirala, Samir, Karkey, Abhilasha, Dongol, Sabina, Wen, Shawn, Smith, Amy B., Maru, Duncan, Basnyat, Buddha, Baker, Stephen, Farrar, Jeremy, Ryan, Edward T., and Hohmann, Elizabeth
- Subjects
TYPHOID fever ,RESOURCE-limited settings ,BACTEREMIA ,SALMONELLA enterica serovar Typhi ,DIAGNOSTIC microbiology ,GRAM-negative bacteria - Abstract
Background: In many rural areas at risk for enteric fever, there are few data on Salmonella enterica serotypes Typhi (S. Typhi) and Paratyphi (S. Paratyphi) incidence, due to limited laboratory capacity for microbiologic culture. Here, we describe an approach that permits recovery of the causative agents of enteric fever in such settings. This approach involves the use of an electricity-free incubator based upon use of phase-change materials. We compared this against conventional blood culture for detection of typhoidal Salmonella. Methodology/Principal Findings: Three hundred and four patients with undifferentiated fever attending the outpatient and emergency departments of a public hospital in the Kathmandu Valley of Nepal were recruited. Conventional blood culture was compared against an electricity-free culture approach. Blood from 66 (21.7%) patients tested positive for a Gram-negative bacterium by at least one of the two methods. Sixty-five (21.4%) patients tested blood culture positive for S. Typhi (30; 9.9%) or S. Paratyphi A (35; 11.5%). From the 65 individuals with culture-confirmed enteric fever, 55 (84.6%) were identified by the conventional blood culture and 60 (92.3%) were identified by the experimental method. Median time-to-positivity was 2 days for both procedures. The experimental approach was falsely positive due to probable skin contaminants in 2 of 239 individuals (0.8%). The percentages of positive and negative agreement for diagnosis of enteric fever were 90.9% (95% CI: 80.0%–97.0%) and 96.0% (92.7%–98.1%), respectively. After initial incubation, Salmonella isolates could be readily recovered from blood culture bottles maintained at room temperature for six months. Conclusions/Significance: A simple culture approach based upon a phase-change incubator can be used to isolate agents of enteric fever. This approach could be used as a surveillance tool to assess incidence and drug resistance of the etiologic agents of enteric fever in settings without reliable local access to electricity or local diagnostic microbiology laboratories. Author Summary: Every year, 20 million people worldwide suffer from typhoid, a bacterial infection spread by contaminated food and water, and over 200,000 die from the infection. However, few data are available on the prevalence and antimicrobial resistance profiles of the causative agents of typhoid, especially in settings without reliable access to laboratories and electricity. Here, we describe an approach that permits recovery of the causative agents of typhoid that requires no electricity, laboratory infrastructure, or specialized laboratory personnel at the site of patient contact. This approach involves the use of an electricity-free incubator, consisting of an insulated container and reusable packets filled with a chemical that upon warming in hot water or direct sun, maintains 38°C for 24 hours. We used blood culture bottles with a color indicator that signals growth of bacteria and an antibiotic that selects for Gram-negative bacteria. We validated this approach in a clinical study among individuals with fever presenting to a hospital in urban Nepal, demonstrating that the approach performed comparably to conventional blood culture for isolating the bacteria causing typhoid. Such an approach would permit an estimate of the burden of typhoid in areas where such data are lacking, which could inform control strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF