Özgür Çelebi

The Use of Germinants to Potentiate the Sensitivity of Bacillus anthracis Spores to Peracetic Acid

Elimination of Bacillus anthracis spores from the environment is a difficult and costly process due in part to the toxicity of current sporicidal agents. For this reason we investigated the ability of the spore germinants L-alanine (100 mM) and inosine (5 mM) to reduce the concentration of peracetic acid (PAA) required to inactivate B. anthracis spores. While L-alanine significantly enhanced (p = 0.0085) the bactericidal activity of 500 ppm PAA the same was not true for inosine suggesting some form of negative interaction. In contrast the germinant combination proved most effective at 100 ppm PAA (p = 0.0009). To determine if we could achieve similar results in soil we treated soil collected from the burial site of an anthrax infected animal which had been supplemented with spores of the Sterne strain of B. anthracis to increase the level of contamination to 104 spores/g. Treatment with germinants followed 1 h later by 5000 ppm PAA eliminated all of the spores. In contrast direct treatment of the animal burial site using this approach delivered using a back pack sprayer had no detectable effect on the level of B. anthracis contamination or on total culturable bacterial numbers over the course of the experiment. It did trigger a significant, but temporary, reduction (p < 0.0001) in the total spore count suggesting that germination had been triggered under real world conditions. In conclusion, we have shown that the application of germinants increase the sensitivity of bacterial spores to PAA. While the results of the single field trial were inconclusive, the study highlighted the potential of this approach and the challenges faced when attempting to perform real world studies on B. anthracis spores contaminated sites.

The effect of prolonged storage on the virulence of isolates of Bacillus anthracis obtained from environmental and animal sources in the Kars Region of Turkey.

The stability of the plasmid-mediated virulence factors of Bacillus anthracis, a tripartite toxin located on pXO1 and an antiphagocytic capsule encoded by genes located on pXO2, following long-term storage was investigated. A collection of 159 isolates of B. anthracis were collected from the Kars region of Turkey between 2000 and 2013 and stored at -20°C in Brucella broth supplemented with 20% glycerine. A total of 142 isolates were recovered of which one failed to express a capsule upon primary culture. A further 35 isolates yielded a mixture of mucoid and non-mucoid colonies; the majority of which had lost the pXO2 plasmid as determined by PCR analysis. Results would suggest that pXO2 is more unstable than pXO1 and that this instability increases with the length of storage. It is possible that the pXO2-deficient isolates of B. anthracis described here could be developed into a vaccine to treat at risk animals in the Kars region as many animal vaccines are based upon pXO2 deficiency.

RAPID IMMUNOFILTRATION ASSAY AS A FIELD DIAGNOSTIC TOOL FOR OVINE BRUCELLOSIS

This work describes the development of two rapid immunofiltration assays, enzymatic (ERIFA) and non-enzymatic (NERIFA), for the rapid detection of ovine anti-Brucella antibodies. Brucella abortus lipopolysaccharide and total bacterial extract were dotted separately as diagnostic antigens on a nitrocellulose filter-membrane of the individual assay unit along with a third dot of purified sheep IgG as an internal control. The assays diagnostic performance was evaluated in comparison with a modified rose bengal test (mRBT) and an indirect enzyme-linked immunosorbent assay (ELISA) through usage of 590 serum samples from healthy, vaccinated, or infected sheep. The ERIFA and indirect ELISA were found to be significantly more sensitive than NERIFA, while mRBT was determined to be statistically equivalent to NERIFA. A perfect agreement (κ = 0.984) and a statistical equivalence to indirect ELISA suggest that the bi-antigenic ERIFA can be used as an “individual rapid ELISA” for screening ovine anti-Brucella antibody both in the field and in limited laboratory conditions.

The role of staphylococci in subclinical mastitis of cows and lytic phage isolation against to Staphylococcus aureus

Aim: This study was conducted to determine the role of Staphylococcus in the formation of subclinical mastitis in cows and to isolate the phage against isolated Staphylococcus aureus strains. Materials and Methods: In this study, 400 milk cows were screened by California Mastitis Test (CMT) for subclinical mastitis and 235 udders of 96 cows, which were determined to be positive, were evaluated for Staphylococcus. Milk samples were evaluated using conventional and molecular methods. In addition, phage isolation studies were performed against S. aureus strains causing mastitis. Results: At the result of cultural examination, of 235 milk samples that were found as positive for mastitis by CMT, a total of 117 (49.7%) Staphylococcus spp. were isolated as a distribution of 74 (63.24%) coagulase-positive staphylococci and 43 (36.75%) coagulase-negative staphylococci. Of these isolates, 76 (64.95%) were characterized as S. aureus both conventional and molecular techniques. Lytic bacteriophages against two S. aureus strains which were isolated from mastitic milk samples were obtained from wastewater samples. Conclusion: The results of this study show that a significant portion of subclinical mastitis was formed by staphylococci. In addition, phage isolation against S. aureus strains isolated can be considered as one of the steps to be applied in the prophylaxis and treatment of such infections.

The mismatched isolation of Brucella strains from nomic hosts

Bulgular: Onaltı koyun örneğinin 15’i B. melitensis ve 14 sığır örneğinin 13’ü B. abortus olarak identifiye edildi. İlginçtir ki, koyun aborte fötusten izole edilen bir suş B. abortus ve sığırdan izole edilen bir suş B. melitensis olarak tanımlandı. Bununla birlikte, koyun fötusundan elde edilen bir suş bütün fenotipik özellikleri yönünden Brucella cinsine benzer karakterde olmasına rağmen genotipik olarak (ne Real Time PCR ne de Bruce-Ladder PCR) Brucella spp. olarak doğrulanamadı ve ileride karakterize edilmek üzere Ochrobactrum spp. şüpheli olarak saklandı.

Protection of farm goats by combinations of recombinant peptides and formalin inactivated spores from a lethal Bacillus anthracis challenge under field conditions

BackgroundBacillus (B.) anthracis, the causal agent of anthrax, is effectively controlled by the Sterne live spore vaccine (34F2) in animals. However, live spore vaccines are not suitable for simultaneous vaccination and antibiotic treatment of animals being at risk of infection in an outbreak situation. Non-living vaccines could close this gap.ResultsIn this study a combination of recombinant protective antigen and recombinant Bacillus collagen-like antigen (rBclA) with or without formalin inactivated spores (FIS), targeted at raising an immune response against both the toxins and the spore of B. anthracis, was tested for immunogenicity and protectiveness in goats. Two groups of goats received from local farmers of the Kars region of Turkey were immunized thrice in three weeks intervals and challenged together with non-vaccinated controls with virulent B. anthracis, four weeks after last immunization. In spite of low or none measurable toxin neutralizing antibodies and a surprisingly low immune response to the rBclA, 80% of the goats receiving the complete vaccine were protected against a lethal challenge. Moreover, the course of antibody responses indicates that a two-step vaccination schedule could be sufficient for protection.ConclusionThe combination of recombinant protein antigens and FIS induces a protective immune response in goats. The non-living nature of this vaccine would allow for a concomitant antibiotic treatment and vaccination procedure. Further studies should clarify how this vaccine candidate performs in a post infection scenario controlled by antibiotics.

Virulence plasmid stability in environmentally occurring Bacillus anthracis from North East Turkey

The Bacillus anthracis virulence plasmid pXO2, which encodes for a polypeptide capsule, can be lost during long term laboratory storage. To determine if pXO2 is lost in nature we screened B. anthracis isolates obtained from B. anthracis spores from contaminated animal burial sites in Turkey for their ability to express a capsule upon primary culture. A total of 672 B. anthracis colonies were examined of which ten produced a mixed mucoid (capsule +ve)/non-mucoid (capsule −ve) phenotype and a further one colony yielded non-mucoid colonies upon repeated culture. Screening by PCR using pXO2 specific primers revealed that seven of these isolates had eliminated the plasmid. Of the four colonies which were positive by PCR, one regained the ability to express a capsule upon repeated culture suggesting that the defect was reversible. This is an important observation as capsule expression is a principal marker of virulence and in the absence of PCR serves as a key diagnostic marker. The results of this preliminary study suggest that pXO2 is lost in nature and that further studies are need to determine the mechanisms by which this occurs.