Tetracycline resistance phenotypes and genotypes of coagulase-negative staphylococcal isolates from bubaline mastitis in Egypt.

AIM: This study was devoted to elucidate the tetracycline resistance of coagulase-negative staphylococci (CNS) derived from normal and subclinical mastitic (SCM) buffaloes' milk in Egypt. MATERIALS AND METHODS: A total of 81 milk samples from 46 normal buffalo milk samples and 35 SCM buffalo milk samples at private dairy farms of Egypt were used in this study. CNS were identified using phenotypic and molecular methods (polymerase chain reaction [PCR]). CNS isolates were tested for tetracycline resistance using routine methods and multiplex PCR targeting tetracycline (tet) resistance genes followed by sequencing of positive PCR products and phylogenetic analysis. RESULTS: Isolation and identification of 28 (34.5%) CNS from normal and SCM buffaloes' milk, namely, Staphylococcus intermedius (39.2%), Staphylococcus xylosus (25.0%), Staphylococcus epidermidis (10.7%), Staphylococcus hominis (10.7%), and 3.5% to each of Staphylococcus sciuri, Staphylococcus hyicus, Staphylococcus lugdunensis, and Staphylococcus simulans. Using nested PCR, all the 28 CNS isolates revealed positive for 16srRNA gene specific for genus staphylococci and negative for thermonuclease (nuc) gene specific for Staphylococcus aureus species. The presence of tetracycline resistance-encoding genes (tetK, tetL, tetM, and tetO) was detected by multiplex PCR. All isolates were negative for tetL, M, and O genes while 14 (50%) CNS isolates were positive for tetK gene, namely, S. lugdunensis (100%), S. hominis (100%), S. epidermidis (66.6%), S. intermedius (45.4%), and S. xylosus (42.8%). Nucleotide sequencing of tetK gene followed by phylogenetic analysis showed the high homology between our CNS isolates genes of tetracycline resistance with S. aureus isolates including Egyptian ones. This proves the transfer of the tetracycline resistance encoding genes between coagulase-negative and coagulase positive Staphylococcus spp. CONCLUSION: CNS isolates have distinguishingly high resistance to tetracycline. Abundant tetracycline usage for mastitis treatment leads to the spread of genetic resistance mechanisms inside CNS strains and among all Staphylococcus spp. Consequently, tetracycline is not effective anymore.

Protective efficacy of a prime-boost protocol using H5-DNA plasmid as prime and inactivated H5N2 vaccine as the booster against the Egyptian avian influenza challenge virus.

In this study, a recombinant DNA plasmid was constructed, encoding for HA1 of a selected Egyptian H5N1 virus (isolated during the 2012 outbreaks). In the immunization and challenge experiments, SPF chickens received 1 or 2 doses of H5-DNA plasmid prime, and boosted with the inactivated H5N2 vaccine. Haemagglutination inhibition (HI) titers, protection levels, and the magnitude of virus shedding were compared to that of the chickens that received either DNA plasmid or inactivated H5N2 vaccine alone. H5N1 virus A/chicken/Egypt/128s/2012 (H5N1) highly pathogenic avian influenza (HPAI) clade 2.2.1/C was used for the challenge. Chickens immunized with 1 or 2 doses of H5-DNA vaccine failed to overcome the challenge with 0% and 10% protection, respectively. Quantitative real-time reverse transcription-PCR revealed virus shedding of 2.2 x 104 PCR copies/ml 3 days post challenge (dpc) in the only surviving bird from the group that received 2 doses of plasmid. However, chickens immunized with 1 or 2 doses of H5-DNA plasmid as prime and inactivated H5N2 vaccine as booster, showed 80% protection after challenge, with a viral shedding of 1.2 x 104 PCR copies/ml (1 dose) and 1.6 x 104 PCR copies/ml (2 doses) 3 dpc. The surviving birds in both groups did not shed the virus at 5 and 7 dpc. In H5N2-vaccinated chickens, protection levels were 70% with relatively high virus shedding (1.8 x 104 PCR copies/ml) 3 dpc. HI titers were protective to the surviving chickens. This study reports the efficacy of H5-DNA plasmid to augment reduction in viral shedding and to provide better protection when applied in a prime-boost program with the inactivated AI vaccine.

Emergence of foot-and-mouth disease virus SAT 2 in Egypt during 2012.

The epidemiology of foot-and-mouth disease (FMD) in North Africa is complicated by the co-circulation of endemic FMD viruses (FMDV), as well as sporadic incursions of exotic viral strains from the Middle East and Sub-Saharan Africa. This report describes the molecular characterization of SAT 2 FMD viruses that have caused widespread field outbreaks of FMD in Egypt during February and March 2012. Phylogenetic analysis showed that viruses from these outbreaks fell into two distinct lineages within the SAT 2 topotype VII, which were distinct from a contemporary SAT 2 lineage of the same toptype from Libya. These were the first FMD outbreaks due to this serotype in Egypt since 1950 and required the development of a tailored real-time reverse-transcription PCR assay that can be used in the laboratory to distinguish FMD viruses of these lineages from other endemic FMD viruses that might be present in North Africa. These data highlight the ease by which FMDV can cross international boundaries and emphasize the importance of deploying systems to continuously monitor the global epidemiology of this disease.

Effect of some antioxidants on canola plants grown under soil salt stress condition.

In this study, two field experiments were carried out during the two growing seasons (2005-2006 and 2006-2007) to investigate the role of some applied antioxidants (spermine 10 mg L(-1) and ascorbic acid 200 mg L(-1)) in counteracting the harmful effect of soil salinity stress (10.1 or 14.6 dS m(-1)) on canola plants. Growth characters, yield and its components as well as biochemical constituents were studied in the two growing seasons. The results showed that all growth characters including; plant height, leaves number and area/plant, shoot and root dry weight as well as yield and its components including; fruit number/plant, number of fruiting branches, seed number/fruit, seed yield/plant and seed oil content of canola plant were decreased with increasing soil salt level (A2) comparing with (A1). On the other hand, applied antioxidants spermine 10 mg L(-1) and ascorbic acid 200 mg L(-1)) increased growth and yield of canola plant during the two growing seasons. However, the applied antioxidants were more effective under the first soil salt condition (A1) soil salt stress levels (A2) decreased each of photosynthetic pigments, K and P contents, while increased proline, soluble sugar, ascorbic acid, Na and Cl contents compared with (A1). On the other hand, applied antioxidants increased each of photosynthetic pigments, proline, soluble sugar, N, K and P contents, while decreased Na and Cl contents in canola plant under soil salt stress (A1 and A2) during the two growing seasons. It could be concluded that applied antioxidants could counteract the harmful effect of salt soil stress on growth, yield and biochemical constituents of canola plant.

Quantitaion of collagen in the wall of contracted schistosomal bladder.

Biochemical assay of vesical collagen was carried out in six cases of contracted schistosomal bladders and five controls. It revealed 11.52 and 9.56 per cent of collagen by weight respectively. Detrusor myopathy seems to be more important than fibrosis. Quantitation of the muscle mass in these cases is needed.