Isolation and antimicrobial susceptibility of Streptococcus castoreus isolated from carcasses of European beavers (Castor fiber) in Germany.

Streptococcus (S.) castoreus was isolated from seven beavers (Castor fiber), which were found dead in the federal state of Brandenburg, Germany, and submitted to the Berlin-Brandenburg State laboratory for post mortem diagnostics. The isolates originated from various inflammatory processes where they were associated with other Gram negative and Gram positive aerobic and/or anaerobic bacteria (i. e. Actinobacillus sp., species of the Actinomycetaceae family, coliform bacteria, Fusobacterium sp., Prevotella sp.), but also from cloacal swabs. Testing their antimicrobial susceptibility, all S. castoreus isolates and the type strain S. castoreus (DSM 17536) were classified as being susceptible to penicillin G, ampicillin, amoxicillin-clavulanic acid, 1st generation cephalosporins, erythromycin, tetracycline, and chloramphenicole but intermediate to gentamicin. Considering both the polymicrobial flora isolated from the inflamed tissues and the fact that antimicrobials of a narrow spectrum (namely penicillins, 1st generation cephalosporins, macrolids and lincosamids) can be toxic to rodents, chloramphenicol might be a suitable drug for treatment of beavers suffering from S. castoreus (mixed)-bacterial infections.

Changes in faecal bacteria and metabolic parameters in foals during the first six weeks of life.

Many foals develop diarrhoea within the first two weeks of life which has been suggested to coincide with postpartum oestrus in their dams. To analyse the pathogenesis of this diarrhoea we have determined faecal bacteria in foals and their dams (n=30 each), and serum IGF-1 and γ-globulins for 6 weeks after birth. In addition, effects of ß-carotene supplementation to mares (group 1: 1000 mg/day, n=15, group 2: control, n=15) on diarrhoea in foals were studied. Diarrhoea occurred in 92 and 79% of foals in groups 1 and 2, respectively, but was not correlated with oestrus in mares. Beta-carotene supplementation was without effect on foal diarrhoea. In mares, bacterial flora remained stable. The percentage of foals with cultures positive for E. coli was low at birth but increased within one day, the percentage positive for Enterococcus sp. was low for 10 days and for Streptococcus sp. and Staphylococcus sp. was low for 2-4 weeks. By 4 weeks of age, bacterial flora in foals resembled an adult pattern. Concentration of serum IGF-1 was low at birth (group 1: 149 ± 11, group 2: 166 ± 17ng/ml), increased after day 1 (day 7 group 1: 384 ± 30, group 2: 372 ± 36) but at no time differed between groups. Serum γ-globulin concentration in foals was low before colostrum intake and highest on day 1 (p<0.001 over time). In conclusion, neonatal diarrhoea in foals does not coincide with postpartum oestrus in their dams but with changes in intestinal bacteria and is not influenced by ß-carotene supplementation given to mares.

[Characterisation of a phenotypic monophasic variant belonging to Salmonella enterica subsp. enterica serovar Typhimurium from wild birds and its possible transmission to cats and humans]. / Charakterisierung einer phänotypisch monophasischen Variante von Salmonella enterica subsp. enterica Serovar Typhimurium bei Wildvögeln und deren mögliche Ubertragung auf Hauskatzen und Menschen.

In the last two years The National Salmonella Reference Laboratory (NRL-Salm) received an accumulating number of salmonellae with sero-formula 4,12:-:1,2 isolated from perished wild birds, particularly siskins. Within these strains flagellar antigen of the first phase was phenotypically not detectable. By PCR a fragment could be amplified coding specifically for the H:i-flagellar antigen. Consequently, this is a phenotypically monophasic variant of Salmonella enterica subsp. enterica serovar Typhimurium var. copenhagen with the sero-formula 4,12:-:1,2. Phage-typing showed most of the isolates belonged to phage type DT40. Some other strains harboured the same lysis pattern but could not assign to a definite phage type. Those strains are designated as RDNC (react with phages but does not conform with definite or provisorial types). Pulsed field gel-electrophoresis (PFGE) confirmed those two lineages of the monophasic variant. Phage type DT40 isolates from humans or cats, able to express both flagellar antigens, did not differ in genotypic properties from those not able to express the flagellar antigen of the first phase. Salmonella strains with identical genotypic characteristics have been isolated from wild birds, human cases particular infants and also cats. This refers to a direct or indirect transmission of the pathogen from wild bird to human. By eating or getting in contact with contaminated birds domestic cats could play an important role as vehicle between bird and human.

Response of Streptococcus suis to iron-restricted growth conditions at high and low oxygen availability.

Streptococcus suis (S. suis) is an important pathogen in pigs and has to overcome strict iron limitations in its host environment. Here, we studied iron-restricted growth of a highly virulent S. suis strain in vitro at aerobic and CO2-enriched growth conditions. At both conditions, depleting of iron in the culture medium with nitrilotriacetic acid (NTA) resulted in decreased growth rates and down regulation of several proteins. Sensitivity to NTA was significantly higher at aerobic versus CO2-enriched conditions. Growth could not be restored by addition of host iron sources such as ferritin, hemin, hemoglobin, lactoferrin or transferrin. Accordingly, S. suis was not able to produce detectable amounts of siderophores. On the other hand, growth at iron-restricted conditions was fully restored by addition of Mn2+ (at aerobic and CO2-enriched conditions) or Mg2+ (only at CO2-enriched conditions). In conclusion our results suggest that, unlike many other bacteria, S. suis adapts to iron restricted conditions by a change in its metabolism in order to replace Fe2+ by Mn2+ or Mg2+ rather than by expressing specific iron uptake systems.

Identification and characterization of two temperature-induced surface-associated proteins of Streptococcus suis with high homologies to members of the Arginine Deiminase system of Streptococcus pyogenes.

The present study was performed to identify stress-induced putative virulence proteins of Streptococcus suis. For this, protein expression patterns of streptococci grown at 32, 37, and 42 degrees C were compared by one- and two-dimensional gel electrophoresis. Temperature shifts from 32 and 37 to 42 degrees C induced expression of two cell wall-associated proteins with apparent molecular masses of approximately 47 and 53 kDa. Amino-terminal sequence analysis of the two proteins indicated homologies of the 47-kDa protein with an ornithine carbamoyltransferase (OCT) from Streptococcus pyogenes and of the 53-kDa protein with the streptococcal acid glycoprotein (SAGP) from S. pyogenes, an arginine deiminase (AD) recently proposed as a putative virulence factor. Cloning and sequencing the genes encoding the putative OCT and AD of S. suis, octS and adiS, respectively, revealed that they had 81.2 (octS) and 80.2% (adiS) identity with the respective genes of S. pyogenes. Both genes belong to the AD system, also found in other bacteria. Southern hybridization analysis demonstrated the presence of the adiS gene in all 42 serotype 2 and 9 S. suis strains tested. In 9 of these 42 strains, selected randomly, we confirmed expression of the AdiS protein, homologous to SAGP, by immunoblot analysis using a specific antiserum against the SAGP of S. pyogenes. In all strains AD activity was detected. Furthermore, by immunoelectron microscopy using the anti-S. pyogenes SAGP antiserum we were able to demonstrate that the AdiS protein is expressed on the streptococcal surface in association with the capsular polysaccharides but is not coexpressed with them.