Case-Control Study To Determine whether River Water Can Spread Tetracycline Resistance to Unexposed Impala ( Aepyceros melampus ) in Kruger National Park (South Africa)

Abstract

A case-control study was performed in the Kruger National Park (KNP), South Africa, to find out whether impala (Aepyceros melampus) were more likely to harbor tetracycline-resistant Escherichia coli (TREC) in their feces when they drank from rivers that contained these bacteria than when they drank from rivers that were uncontaminated with TREC. The following five perennial rivers were selected: the Crocodile, the Letaba, the Olifants, the Sabie, and the Sand. Samples of river water (n ‫؍‬ 33) and feces (n ‫؍‬ 209), collected at 11 different sites, were cultured for E. coli. The resulting colonies were screened for tetracycline resistance by use of the Lederberg replica plating method (breakpoint, 4 mg/liter). A resistant and/or a susceptible isolate was then selected from each sample and subjected to the CLSI MIC broth microdilution test for tetracyclines. Among the 21 water specimens contaminated by E. coli, 19.05% (n ‫؍‬ 4) were found to be resistant by the MIC method (breakpoint, >8 mg/liter). This led to the Crocodile, Olifants, and Letaba rivers being classified as TREC positive. Among the 209 impala feces sampled, 191 were positive for the presence of E. coli (91.38%). Within these (n ‫؍‬ 191), 9.95% (n ‫؍‬ 19) of the isolates were shown to be TREC by the MIC method. It was found that 1.11% (n ‫؍‬ 1) of the E. coli isolates cultured from the feces of the control group (n ‫؍‬ 90) were TREC, in comparison with 17.82% (n ‫؍‬ 18) of those in feces from the exposed group (n ‫؍‬ 101). The calculation of the odds ratio showed that impala drinking from TREC-contaminated rivers were 19.3 (2.63 to 141.69) times more likely to be infected with TREC than were unexposed impala. This is a significant finding, indicating that surface water could be a possible source of antimicrobial resistance in naïve animal populations and that impala could act as sentinels for antimicrobial resistance.

FROM WHENCE THEY CAME—ANTIBIOTIC-RESISTANTESCHERICHIA COLIIN AFRICAN WILDLIFE

“…In this manner, water can act as a powerful exposure medium for the introduction of antimicrobial resistance into naïve populations (Mariano et al 2009). Human fecal material can enter waterways with stormwater runoff, sewage system breaks, or flooding of septic tanks (McCarthy et al 2004), as well as direct defecation and pollution from livestock and wildlife when animals congregate around water resources.…”

Yeasts from Macrobrachium amazonicum: a focus on antifungal susceptibility and virulence factors of Candida spp.

“…Based on this, crustaceans, including M. amazonicum , and fishes can be used as sentinels for the occurrence of resistant yeasts in the environment. Several animal species have been reported as sentinels for the occurrence of resistant bacteria in the wild, including predatory fishes (Blackburn et al , 2010) and terrestrian mammals (Routman et al , 1985; Costa et al , 2008; Mariano et al , 2009). Interestingly, all of these authors reported that the occurrence of resistant bacteria was associated with the close relationship between these wild animals or their environment and human beings and that water was the main vehicle for spreading chemical compounds involved in the development of resistance.…”

The Relationships between Somatic Cells and Isoleucine, Leucine and Tyrosine Content in Cow Milk

“…The sample size was calculated using the formula n = Z 2 * p * (1 − p)/C 2 , where Z is the Z-value (e.g., 1.96 for a 95% confidence level), p is the expected prevalence, expressed as a decimal and C is the confidence interval, expressed as a decimal [17]. With an expected prevalence of 50% (0.5), a confidence interval of 10 and a confidence level of 0.95 a sample size of 63 animals is then required.…”