Panton-Valentine leukocidin does play a role in the early stage of Staphylococcus aureus skin infections: a rabbit model.

Despite epidemiological data linking necrotizing skin infections with the production of Panton-Valentine leukocidin (PVL), the contribution of this toxin to the virulence of S. aureus has been highly discussed as a result of inconclusive results of in vivo studies. However, the majority of these results originate from experiments using mice, an animal species which neutrophils--the major target cells for PVL--are highly insensitive to the action of this leukocidin. In contrast, the rabbit neutrophils have been shown to be as sensitive to PVL action as human cells, making the rabbit a better experimental animal to explore the PVL role. In this study we examined whether PVL contributes to S. aureus pathogenicity by means of a rabbit skin infection model. The rabbits were injected intradermally with 10(8) cfu of either a PVL positive community-associated methicillin-resistant S. aureus isolate, its isogenic PVL knockout or a PVL complemented knockout strain, and the development of skin lesions was observed. While all strains induced skin infection, the wild type strain produced larger lesions and a higher degree of skin necrosis compared to the PVL knockout strain in the first week after the infection. The PVL expression in the rabbits was indirectly confirmed by a raise in the serum titer of anti-LukS-PV antibodies observed only in the rabbits infected with PVL positive strains. These results indicate that the rabbit model is more suitable for studying the role of PVL in staphylococcal diseases than other animal models. Further, they support the epidemiological link between PVL producing S. aureus strains and necrotizing skin infections.

Mixed Giardia duodenalis assemblage A, B, C and E infections in pet chinchillas (Chinchilla lanigera) in Flanders (Belgium).

Worldwide there is an increasing trend to keep exotic animals as pets. In contrast to domestic animals, few studies have addressed the importance of infectious diseases of these exotic animals harbor. Chinchillas are host to Giardia, but prevalence studies are scarce. Moreover, little is known about their role as a zoonotic reservoir for Giardia. Therefore, the objective of the present study was (1) to study the occurrence of Giardia in pet chinchillas, (2) to identify risk factors and (3) to determine the role of these animals as potential zoonotic reservoir. To this end, pet chinchillas (Chinchilla lanigera) from both pet owners and breeders in Flanders (Belgium) were screened for the presence of Giardia spp. using a sedimentation flotation technique. A questionnaire was distributed among the pet owners to identify putative risk factors. A subset of the Giardiaisolates was characterized by direct sequencing of the ß-giardin gene. In addition, assemblage specific PCRs targeting the triose phosphate isomerase (tpi) gene were performed. Of the 80 chinchillas screened, 53 (66.3%) excreted cysts of Giardia. Youngsters and animals participating in shows were significantly more at risk for infection. A total of 22 isolates were characterized. Direct sequencing of the ß-giardin gene solely revealed the presence of G. duodenalis assemblage B. The assemblage specific PCRs confirmed these findings, but also revealed the presence of assemblage A (11 samples), C (15 samples) and E (2 samples). This study indicates that multiple Giardia spp. are highly prevalent in pet chinchillas and that these animals are a potential reservoir for zoonotic transmission. In addition, the results highlight the benefit of using an assemblage specific PCR in molecular studies as mixed infections are likely to be missed using conventional PCR approaches.