Necrotizing fasciitis in captive juvenileCrocodylus porosuscaused byStreptococcus agalactiae: an outbreak and review of the animal and human literature

Abstract

We observed an outbreak of necrotizing fasciitis associated with Streptococcus agalactiae infection in a group of juvenile saltwater crocodiles (Crocodylus porosus). We undertook screening of crocodiles and the environment to clarify the source of the outbreak and evaluated the isolates cultured from post-mortem specimens with molecular methods to assess clonality and the presence of known group B streptococcal virulence determinants. The isolates were indistinguishable by pulsed-field gel electrophoresis. They were a typical serotype Ia strain with the Calpha-like protein gene, epsilon (or alp1), the mobile genetic elements IS381 ISSag1 and ISSag2, and belonged to multi-locus sequence type (ST) 23. All of these characteristics suggest they were probably of human origin. We review the medical and veterinary literature relating to S. agalactiae necrotizing fasciitis, epidemiology and virulence determinants.

Serotype distribution and antimicrobial susceptibilities of Streptococcus agalactiae isolated from infected cultured tilapia (Oreochromis niloticus) in Thailand: Nine-year perspective

“…To date, only serotypes Ia, Ib and III have been previously reported in fish (Vandamme et al, 1997;Evans et al, 2008;Suanyuk et al, 2008;Suwannasang et al, 2014). GBS is an emerging zoonotic agent isolated from piscine, dolphin, bovine, crocodile, camel and human sources (Ip et al, 2006;Bishop et al, 2007;Evans et al, 2008;Fischer et al, 2013). Multilocus sequence typing (MLST) of some GBS isolates from fish in Asia, including Thailand, indicated that these belong to sequence type (ST)-7/serotype Ia and ST-283/serosubtype III-4, which are associated with invasive disease of humans in Asia (Evans et al, 2008;Delannoy et al, 2013;Kayansamruaj et al, 2014).…”

“…GBS is an emerging zoonotic agent isolated from terrestrial and aquatic animals (Martinez et al, 2000;Duremdez et al, 2004;Bishop et al, 2007;Evans et al, 2008;Suanyuk et al, 2008;Fischer et al, 2013). In order to treat bacterial diseases in cultured tilapia, oxytetracycline is permitted for use in Thai aquaculture (Baoprasertkul et al, 2012).…”

On the origin of Group B Streptococcus from disease outbreaks in wild marine fish in Australia

“…Contrary to the piscine isolates, the crocodile strain, QMA0336, isolated on a farm in the Northern Territory (Darwin) from a case of necrotizing fasciitis in a captive juvenile Crocodylus porosus (Bishop et al, 2007) is unrelated to the ST-261 group. It was identified as ST-23, serotype Ia, as were the two human isolates included in our study, collected from two cases of infection in Townsville, QMA0355 and QMA0357, which all belong to CC 23 ( Fig.…”

“…ST-23 is one of the major successful clones identified worldwide, the serotype Ia is associated in humans (Brochet et al, 2006), serotype III in dairy cattle (Brochet et al, 2006;Skov Sorensen et al, 2010), and it has been isolated from Scottish pinniped also serotype Ia, suggesting a possible transmission from human to grey seals via contaminated surface water (Delannoy et al, 2013). Establishing an unambiguous human origin of the Australian ST-23 serotype Ia in juvenile crocodiles remains to be confirmed (Bishop et al, 2007).…”

“…agalactiae is also a significant bacterial pathogen of humans, causing septicaemia and meningitis in newborn babies and disease in immuno-compromised humans (Dermer et al, 2004). It also causes mastitis in cows, and disease in wild and captive saltwater crocodiles, dolphins, frogs and lizards (Amborski et al, 1983;Bishop et al, 2007;Evans et al, 2006b;Hetzel et al, 2003;Keefe, 1997;Zappulli et al, 2005).…”