Risk factors for infection with pathogenic and antimicrobial-resistant fecal bacteria in northern elephant seals in California.
OBJECTIVE
The goal of this study was to identify potential environmental and demographic factors associated with Campylobacter jejuni (C. jejuni), Salmonella enterica (Salmonella spp.), and antimicrobial-resistant Escherichia coli (E. coli) infection in northern elephant seals stranded along the California coastline.


METHODS
E. coli, Salmonella spp., and C. jejuni were isolated from rectal swabs from 196 juvenile northern elephant seals, which were found stranded and alive along the California coast and brought to The Marine Mammal Center in Sausalito, California, for rehabilitation. Gender, weight, county where the animal stranded, month stranded, coastal human population density, exposure to sewage outfall or freshwater outflow (river or stream), and cumulative precipitation in the previous 24 hours, seven days, 30 days, 90 days, and 180 days were analyzed as potential risk factors for infection.


RESULTS
The odds of C. jejuni and antimicrobial-resistant E. coli were higher in feces of seals stranded at sites with higher levels of freshwater outflow compared with lower levels of freshwater outflow. The odds of Salmonella spp. in feces were 5.4 times greater in seals stranded in locations with lower levels of 30-day cumulative precipitation, along with substantially lower odds of Salmonella shedding for seals stranded in Monterey or Santa Cruz county compared with seals stranded in regions further north or south of this central California location.


CONCLUSIONS
Juvenile northern elephant seals that have entered the water are being colonized by antimicrobial-resistant and pathogenic fecal bacteria that may be acquired from terrestrial sources transmitted via river and surface waters.
Stoddard
Robyn A
RA
Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA. StoddardR@tmmc.org
Atwill
Edward R
ER
Gulland
Frances M D
FM
Miller
Melissa A
MA
Dabritz
Haydee A
HA
Paradies
Dave M
DM
Worcester
Karen R
KR
Jang
Spencer
S
Lawrence
Judy
J
Byrne
Barbara A
BA
Conrad
Patricia A
PA
D000818:Animals; D002140:California / Q000453:epidemiology; D002169:Campylobacter Infections / Q000453:epidemiology* / Q000662:veterinary*; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000302:isolation & purification; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D005618:Fresh Water; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012481:Salmonella Infections, Animal / Q000453:epidemiology*; D019779:Salmonella enterica / Q000187:drug effects* / Q000302:isolation & purification; D046048:Seals, Earless / Q000382:microbiology*; D012722:Sewage; D014730:Veterinary Medicine; D014871:Water Microbiology
D012722:Sewage