Antibiotic-resistance patterns of enteric bacteria of wild mammals on the Krakatau Islands and West Java, Indonesia

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Abstract
Apart from feral pigs on Panjang, rats (Rattus rattus and Rattus tiomanicus) and bats (various families, genera and species) are the only mammals resident on the Karkatau Islands. The two species of rat occur on separate islands, R. rattus omn Rakata and R. tiomanicus on Panjang and Sertung. Both occur on Java. Of the two genera of bats examined, species of Cynopterus were found on Java and all the Krakatau islands, whereas Myotis muricola muricola was detected only on Java and Rakata. The main faecal bacteria of these mammals were shown to be Escherichia coli and species of Klebsiella, Enterobacter and Citrobacter, with other bacteria (e.g. Proteus sp., Pseudomonas sp., Aeromonas sp., Serratis sp., Proteus/Providencia sp., Morganella sp. and Streptococcus faecalis) being present in only a minority of individuals. Significant differences were noted between the faecal floras of the two rat species. E. coli was always present in R. rattus, but was less frequent in R. tiomanicus (p < 0.05), whereas species of Klebsiella and Citrobacter were less frequent in R. rattus than in R. tiomanicus (p < 0.05). Differences between the faecal floras of the two bat genera were less significant, with the four main faecal bacteria being present in each genus. However, some individual M. muricola muricola yielded S. faecalis, Morganella sp. and Proteus/Providencia sp. whereas species of Cynopterus did not (p < 0.05). S. faecalis was detected in rats and the bat M. muricola muricola on Java, but not in mammals on the Krakataus. This may be related to the absence of humans and their domesticated animals on the Krakatau islands. Only on Java did rats carry tetracycline-resistant E. coli or tetracycline-resistant species of Klebsiella. This may be related to the widespread use of tetracycline by humans on Java, where tetracycline is available without medical supervision. Isolates of E. coli from rats on Panjang were more resistant to chloramphenicol than were E. coli isolated from rats on the other islands of the Krakatau group, and isolates of Klebsiella from bats on Panjang were more resistant to sulphamethoxazole than were Klebsiella species isolated from bats on Rakata. The reason for faecal bacteria from Panjang mammals being more antibiotic resistant than those from mammals on other islands of the group is unclear, but may be related to differences in diet and vegetation, or the presence of feral pigs on Panjang only.