Acinetobacter johnsonii and Acinetobacter lwoffii - the emerging fish pathogens

Abstract

The aim of this study was to characterise Acinetobacter sp. isolated from fish. Eight isolates obtained from diseased rainbow trout and common carp cultured in Poland were analysed. The isolates were identified using API 20 NE system as Acinetobacter sp. Afterwards, they were identified by sequencing 16S rDNA gene fragment. The bacteria were identified as A. johnsonii (two isolates), A. lwoffii (two isolates), A. junii/johnsonii (one isolate), A. calcoaceticus (one isolate), and Acinetobacter sp. (two isolates). The drug resistance of isolates was examined. The majority of the isolates were resistant to ampicilin, amoxicillin, and cephalothin and all demonstrated sensitivity to fluoroquinolones, except of one isolate. Two isolates were selected for the experimental infection of trout and carp to confirm their pathogenicity. Experimentally infected fish showed disease symptoms similar to those observed in fish naturally infected with these bacteria. This is the first report concerning pathogenicity of A. johnsonii for rainbow trout and A. lwoffii for common carp. These bacteria were regarded as emerging opportunistic pathogens of fish farmed in Poland. Acinetobacter strains are commonly known as microorganisms transmitting the antibiotic resistance genes. Therefore, they might have a great impact on the resistance transfer in aquaculture.

Structure of the O-specific polysaccharide from the lipopolysaccharide of Aeromonas sobria strain Pt312

“…sobria strain Pt312 was isolated from a kidney of rainbow trout without disease symptoms during an outbreak of motile aeromonad septicemia (MAS) on a Polish trout farm and identified to the species level by restriction analysis of 16S rRNA gene amplified by polymerase chain reaction. 11 Based on virulence-associated markers (hemolytic, gelatinolytic, and caseinolytic activities), strain Pt312 was classified as avirulent for fish, as reported previously. 11 For LPS analysis, A. sobria strain Pt312 was obtained from the collection of the Department of Fish Diseases, National Veterinary Research Institute (Puławy, Poland).…”

“…11 Based on virulence-associated markers (hemolytic, gelatinolytic, and caseinolytic activities), strain Pt312 was classified as avirulent for fish, as reported previously. 11 For LPS analysis, A. sobria strain Pt312 was obtained from the collection of the Department of Fish Diseases, National Veterinary Research Institute (Puławy, Poland). The bacteria were cultivated in tryptic soy broth (TSB) at 28°C for 72 h. The cells were harvested by low speed centrifugation (8000g, 20 min).…”

“…[14][15][16] Here, we report on the structural studies of the OPS liberated from the LPS of Aeromonas sobria strain Pt312, which was isolated from a kidney of apparently healthy rainbow trout (Oncorhynchus mykiss Walbaum) during an outbreak of motile aeromonad septicemia (MAS) on a Polish trout farm. 11 …”

“…However, a lot of commercial fish farms are economically compromised because of the increased Aeromonas infection incidence rates. 11 Since it has been shown that Aeromonas bacteria are able to persist in drinking water for more than one year and there have been a number of well-documented cases of transmission of these bacteria through aquatic weeds, a potential route of entry into fish and consequently into the human body should be considered as a possible public health risk. 12 Although relatively little attention has been given to bacterial pathogens of fish, some aspects of virulence mechanisms including the role of cell-surface components in pathogenicity have been investigated.…”

Bacterial and parasitic factors diagnosed in eel farmed in Poland in the years 2010-2014

“…Zakres metodyki badań ZHW w Olsztynie jest opracowany zgodnie z wymaganiami dla laboratoriów w strukturze Państwowej Inspekcji Weterynaryjnej, zgodnie z przyjętymi zasadami i wymaganiami systemu zarządzania jakością (1,10,11). W analizowanym okresie przebadano łącznie 73 próby ryb (pr, 100%).…”