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EVALUATING THE POTENTIAL SOURCES OF HELICOBACTER PYLORI IN SAN JUAN BAY AND RÍO GRANDE DE LOÍZA ESTUARIES OF PUERTO RICO

Abstract

Fecal contamination of recreational waters can increase the risk of human pathogen exposure and may originate from multiple sources, including human sewage leaks/overflows, stormwater runoff, and animal waste. Because Helicobacter pylori is a widespread human pathogen suspected to transmit through contaminated food or water, this study evaluated H. pylori in Puerto Rico environmental waters and tested whether detections aligned with host-associated fecal markers. We hypothesized that if H. pylori occurrence reflected recent fecal inputs, H. pylori would bepositively associated with the presence of at least one host marker (human, dog, or horse), helping infer the most likely contributing source. Environmental water samples collected in Puerto Rico were provided as pre-filtered membrane samples and processed upon arrival in the laboratory. DNA was extracted from each filter using established environmental protocols to ensure consistent recovery of microbial material. Following extraction, DNA concentration and purity were evaluated with a NanoDrop spectrophotometer to confirm that the samples met quality standards appropriate for quantitative PCR (qPCR). qPCR assays were then carried out to detect H. pylori. Additional qPCR assays were performed for human-, dog-, and horse-associated microbial source tracking markers (and a Leptospira marker) to allow comparison and correlation testing. After amplification, threshold cycle (Ct) values were compiled and converted into presence/absence data. Across 72 samples (including field and laboratory controls), H. pylori DNA was detected in 12 samples (16.7%). Fisher’s exact analyses showed no significant associations between H. pylori positivity and any additional markers tested, indicating that in this dataset H. pylori detection did not track strongly with the host-associated signals measured and underscoring the complexity of linking pathogen detection to specific contamination sources in recreational waters.

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