Hawaiʻi Water Quality report published in Antibiotics Journal

The article Environmental Surveillance and Characterization of Antibiotic Resistant Staphylococcus aureus at Coastal Beaches and Rivers on the Island of Hawai‘i was published in the August edition of the journal Antibiotics. UH Hilo Gradutae Tyler J. Gerken is a co-author of the study, along with: Marilyn C. Roberts, Philip Dykema, Geoff Melly, Darren Lucas, Vanessa De Los Santos, Joenice Gonzalez, Patrick Butaye, and Tracy N. Wiegner.


Staphylococcus aureus are human facultative pathogenic bacteria and can be found as contaminants in the environment. The study was conducted to determine whether methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) isolated from coastal beach and river waters, anchialine pools, sand, and wastewater on the Island of Hawai‘i, Hawai‘i, are a potential health risk.


Water and sand samples were collected multiple times at 36 stations across the three most populous districts in Hawai‘i County, including the most populated district, Hilo, and the less populated ones of South Kohala, North Kona, and Puna. Hilo stations were chosen adjacent to and within the Hilo Bay watershed, spanning ~12 km of coastline, including the Wailuku and Wailoa Rivers and Honoli‘i Stream. A majority of households in Hilo rely on decentralized wastewater management, where ~8700 cesspools leak ~21.2 million liters/day into groundwater, which contaminates nearshore coastal waters. In Hilo, there is a wastewater treatment plant that utilizes a series of gravity-fed systems with pump stations and provides primary and secondary treatment, where effluent is discharged offshore via an ocean outfall. As a result of heavy rainfall, cesspool seepage and sewage overflows periodically occur representing a potential health hazard and thus, sewage was sampled.

Map of the regions surveyed, on each part of Hawaiʻi IslandMap of the regions surveyed, on each part of Hawaiʻi Island

Twenty-one samples were collected from three regions on Hawai‘i Island from July to December 2020 during the COVID-19 pandemic and were characterized using whole-genome sequencing (WGS). Of the 361 samples, 98.1% were positive for Staphylococcus spp. and 7.2% were S. aureus positive (n = 26); nine MRSA and 27 MSSA strains were characterized; multiple isolates were chosen from the same sample in two sand and seven coastal beach water samples. The nine MRSA isolates were multi-drug resistant (6–9 genes) sequence type (ST) 8, clonal complex (CC) 8, SCCmec type IVa (USA300 clone), and were clonally related (0–16 SNP differences), and carried 16–19 virulence factors. The 27 MSSA isolates were grouped into eight CCs and 12 STs. Seventy-eight percent of the MSSA isolates carried 1–5 different antibiotic resistance genes and carried 5–19 virulence factors.

Map showing sample collection locations on Hawaiʻi IslandMap showing sample collection locations on Hawaiʻi Island


Ninety-eight percent (354/361) of the samples were positive for Staphylococcus spp. We found S. aureus in coastal beach and river waters, anchialine pools, and sand at locations with limited human activity on the island of Hawai‘i. This may be a public health hazard.

The MRSA, despite being isolated from two different districts on the island, were clonally related and thus, probably indigenous to the region, as they were also clonally related to strains previously isolated in Hawai‘i. Overall, this indicates that colonization of S. aureus strains may occur at coastal beaches and may, subsequently, spread in the community and cause infections. Additional genomic information of currently circulating strains infecting humans on the island of Hawai‘i are necessary to bring more clarity to the situation.