Staphylococcus warneri and Shewanella putrefaciens Coinfection in Siberian Sturgeon (Acipenser baerii) and Hybrid Sturgeon (Huso huso x Acipenser baerii)Submit Manuscript | http://medcraveonline.com IntroductionFish are in continuous contact with microorganisms in the water and sediment, which influences the microbial species diversity on their skin, gills and alimentary tract [1]. Although all microorganisms are part of the normal aquatic environment, some opportunistic pathogens cause bacterial diseases in fish with high mortality rates [2]. Examples are several Gram-positive and Gram-negative bacteria including Staphylococcus warneri (S. warneri) and Shewanella putrefaciens (S. putrefaciens) [3].From pond water samples at a fish farm, Newaj-Fyzul et al. [4] isolated Gram-positive bacteria identified as Staphylococcus spp. In the belief of Musharrafieh et al. [5] S. warneri is a part of the normal fish microflora, but Gil et al. [6] were the first to describe a disease on rainbow trouts caused by S. warneri, which makes it an opportunistic pathogen. Thereafter, Metin et al. [7] also reported S. warneri infection in rainbow trouts.S. putrefaciens is a Gram-negative facultatively anaerobic bacterium from the Shewanellaceae family. It is usually isolated from sea water, sediment and marine fish [8,9]. The first outbreak of disease caused by S. putrefaciens was described by Saeed et al. [10]. Kozinska & Pekala [8] and Pekala et al.[11] also reported S. putrefaciens infection in fish.The present study describes the first case of S. warneri and S. putrefaciens co-infection in Siberian sturgeons (Acipenser baerii) and hybrid sturgeons (Huso huso x Acipenser baerii). Case PresentationOn a sturgeon farm with recirculation aquaculture systems in North Bulgaria, an average daily mortality of 30 fish has occurred in September 2015 among fish weighing 200-800 g. In this study, a total of 10 fish were used (5 Siberian and 5 hybrid sturgeons).Gross anatomy findings consisted in ulcerations, 1 to 1.5cm in diameter (Figure 1) on the skin and multiple haemorrhages on the ventral part of the body. After dissection of the abdominal cavity, yellow-tinted muscles with multiple haemorrhages were observed (Figure 2). The spleen was hyperemic. The liver was of yellow ochre colour, frail consistency and surface petechial haemorrhages. Small gray-yellowish nodules were detected in some areas. Mesenteric blood vessels were hyperemic, and intestines were filled with bloody liquid content.The specimens for histopathological examination were fixed in 10% neutral formalin and processed by routine histology techniques [12,13]. Cross sections (4 μm) were stained with haematoxylin-eosin (H/E).For microbiology examination, samples from skin lesions, liver, spleen and intestines were collected and cultured on tryptic soy agar (Fluca, India) supplemented with 5% defibrinated ovine blood (TSBA), MacConkey agar (NCIPD, Bulgaria) and GSP agar (Merck, Germany). Plates were incubated aerobically at 37 °C for 24-48 h. In addition, the samples were cul...

This study aimed to investigate the presence of Staphylococcus spp. and Staphylococcus aureus in raw cow milk samples taken from peddlers of five regions in Bulgaria. The results showed that all 44 samples tested were positive for Staphylococcus spp. All isolates were tested for coagulase production and subjected to PCR analysis. PCR amplification of 16S rRNA and nuc genes found the presence of Staphylococcus aureus in 23 (52.3%) of a total of 44 raw milk samples. The number of Staphylococcus spp. ranged from 3x102 to 1.08x106 cfu/ml, and that of Staphylococcus aureus from 1.5x102 to 3.19x105 cfu/ml. It is concluded that control over the hygiene of handling and processing raw milk is essential for its safety.