Skip to main content
ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Infectious Bacterial Diseases Research » Research » Publications at this Location » Publication #301599
Title: Antibiotic efficacy in eliminating leptospiruria in California sea lions (Zalophus californianus) stranding with leptospirosis

Author
item PRAGER, K - University Of California
item Alt, David
item BUHNERKEMPE, MICHAEL - University Of California
item GREIG, DENISE - Marine Mammal Center
item GALLOWAY, RENEE - Centers For Disease Control And Prevention (CDC) - United States
item WU, QINGZHONG - National Oceanic & Atmospheric Administration (NOAA)
item GULLAND, FRANCES - Marine Mammal Center
item LLOYD-SMITH, JAMES - University Of California

Submitted to: Aquatic Mammals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2015
Publication Date: 6/1/2015
Citation: Prager, K.C., Alt, D.P., Buhnerkempe, M.G., Greig, D.J., Galloway, R.L., Wu, Q., Gulland, F.M., Lloyd-Smith, J.O. 2015. Antibiotic efficacy in eliminating leptospiruria in California sea lions (Zalophus californianus) stranding with leptospirosis. Aquatic Mammals. 41(2):203-212.

Interpretive Summary: Leptospira spp are pathogens that can cause clinical illness in livestock, humans and wildlife. A disease syndrome in sea lions has been linked to infection with Leptospira. Effectiveness of current methods for treatment of this infection is unknown. A case study was conducted using 14 California sea lions in a rehabilitation center to evaluate the effectiveness of antibiotic treatment of leptospirosis. Leptospiruria (urinary shedding of leptospires) was assessed using samples collected over time during rehabilitation. Analysis of serum chemistry samples was also used to assess recovery of normal kidney function. Testing was also conducted on serum to check for the presence of anti-Leptospira antibody titers. Animals were initially treated for varying periods with antibiotics from the penicillin family, with some animals receiving additional antibiotics to treat other medical conditions. Presence of leptospires in the urine was evaluated using PCR, as all urine cultures were negative. Leptospiruria persisted beyond the initial course of penicillin family antibiotics in all sea lions, beyond the last treatment in 11/14 sea lions, and beyond recovery of normal kidney function in 13/14 sea lions. Shedding was more likely to stop in animals receiving antibiotics for a greater duration, especially if coverage was uninterrupted. An antibiotic protocol using penicillin family antibiotics commonly used to treat leptospirosis in rehabilitating California sea lions does not eliminate leptospiruria as determined by real-time PCR. This study shows that better antibiotic treatment protocols are needed for marine mammals suffering from the zoonotic disease leptospirosis, an important issue for both marine mammals and for public health.

Technical Abstract: Infection of California sea lions with leptospirosis can result in stranding and death of the animals. Shedding of the infectious organism contributes to spread of the disease to other animals and also poses a threat to human health. This is both for the public interacting with stranded animals and for animal workers involved in their rehabilitation. A prospective case study was conducted using 14 California sea lions in a rehabilitation center to evaluate the efficacy of antibiotic treatment of leptospirosis in sea lions. Leptospiruria (urinary shedding of leptospires) was assessed by real-time PCR of urine and culture, with persistence assessed using longitudinally collected samples. Serum chemistry of longitudinally collected samples was used to assess recovery of normal renal function. Microscopic agglutination testing (MAT) was performed on admit sera to assess anti-Leptospira antibody titers. Animals were initially treated for 5 – 17 days (median=11, mean=10.8) with antibiotics from the penicillin family, with some receiving additional antibiotics to treat other medical conditions. Presence of leptospiruria was assessed using PCR, as all urine cultures were negative. Leptospiruria persisted for at least 8 – 86 days (median=45, mean=46.8), continued beyond the initial course of penicillin family antibiotics in all sea lions, beyond the last antibiotic dose in 11/14 sea lions, and beyond recovery of renal function in 13/14 sea lions. Cessation of leptospiruria was more likely in animals that received antibiotics for a greater duration, especially if coverage was uninterrupted. MAT reactivity patterns were consistent with L. interrogans serovar Pomona infection frequently observed in this population. An antibiotic protocol commonly used to treat leptospirosis in rehabilitating California sea lions does not eliminate leptospiruria as determined by real-time PCR. Protocols given for a longer duration and including other antibiotics may be effective.