No abstract

The aim of this work was to (i) determine the chemical composition of the essential oils of six spices widely cultivated in Egypt (Origanum syriacum, Majorana hortensis, Rosmarinus officinalis, Cymbopogon citratus, Thymus vulgaris, and Artemisia annua); (ii) determine the antioxidant activity of the Egyptian essential oils by means of five different antioxidant tests; and (iii) determine the effectiveness of these essential oils on the inhibition of Listeria innocua CECT 910. There is a great variability in the chemical composition of essential oils obtained from the six Egyptian aromatic plants. Overall, thyme (highest percentage of inhibition of DPPH radical: 89.40%) and oregano (highest percentage of inhibition of TBARS: 85.79) essential oils presented the best antioxidant profiles, whereas marjoram, lemongrass, and artemisia were highly effective in metal chelating but had a pro-oxidative behavior by Rancimat induction test. Lemongrass essential oil showed the highest antibacterial activity against L. innocua with an inhibition zone of 49.00 mm, followed in effectiveness by thyme, marjoram, and oregano.

Background and Aim:Mastitis is one of the most vital noteworthy monetary risks to dairy ranchers and affects reproductive performance in dairy cattle. However, subclinical mastitis (SCM) negatively affects milk quality and quantity and associated with economic losses as clinical mastitis. It is recognizable only by additional testing. Somatic cell count (SCC) is currently used worldwide for the screening of intramammary infection (IMI) infections. However, somatic cells (SC) are affected by numerous factors and not always correlate with infection of the udder. Therefore, the aim of the present study was to evaluate the milk amyloid A (MAA) in the milk of normal and SCM cows and compare the sensitivity of both MAA secretion and SCC in response to mammary gland bacterial infection.Materials and Methods:A total of 272 quarter milk samples collected from 68 Friesian cows after clinical examination for detection of clinical mastitis were employed in this study. All quarter milk samples (272) were subjected to bacteriological examination, while SCs were assessed in samples (220). Following SCC estimation and bacteriological examination, the apparently normal quarter milk samples were categorized into 7 groups and MAA concentration was estimated in normal and subclinical mastitic milk samples.Results:Prevalence of clinical mastitis was 19.12 % (52 quarters), while 80.88 % (220 quarters) were clinically healthy with normal milk secretion. Of those 220 clinically healthy quarter milk samples, 72 (32.73%) showed SCM as detected by SCC (SCC ≥500,000 cells/ml). The most prevalent bacteria detected in this study were streptococci (48.53%), Staphylococcus aureus (29.41%), Escherichia coli (36.76%), and coagulase-negative staphylococci (11.76%). Results of MAA estimation revealed a strong correlation between MAA secretion level and SCC in agreement with the bacteriological examination. Interestingly, there was a prompt increase in MAA concentration in Group III (G III) (group of milk samples had SCC ≤200,000 cells/ml and bacteriologically positive) than Group I (G I) (group of milk samples with SCC ≤500,000 cells/ml and bacteriologically negative), as MAA concentration in G III was about 4 times its concentration in G I.Conclusion:Our study provides a strong evidence for the significance of MAA measurement in milk during SCM, and MAA is more sensitive to IMI than SCC. This can be attributed to rapid and sensitive marker of inflammation. The advantage of MAA over other diagnostic markers of SCM is attributed the minute or even undetectable level of MAA in the milk of healthy animals, it is not influenced by factors other than mastitis, and could be estimated in preserved samples. Therefore, we recommend that estimation of MAA concentration in milk is a more useful diagnostic tool than SCC to detect SCM and to monitor the udder health in dairy cattle.

The ability of biofilm formation seems to play an essential role in the virulence of coagulase-negative staphylococci (CNS). The present work aimed to: (a) evaluate the biofilm-forming ability of different strains of CNS field isolates; (b) evaluate their virulence potential through the assessment of the Madin-Darby canine kidney (MDCK) cytotoxicity assay; (c) determine the frequency of biofilm-associated genes among these CNS isolates. Biofilm markers associated with biofilm formation and MDCK cells cytotoxicity were compared to find possible associations with pathogenicity. CNS isolates (n = 94) belonging to 11 different species were tested for slime production using the tube test (TA) and the Congo red agar plate test (CRA), while the presence of icaA and icaD genes were evaluated by d-PCR. Two points were addressed for the first time: (1) the specific relationship between slime phenotype and icaD gene expression; (2) the specific relationship between slime phenotype, icaAD genes, and MDCK cytotoxicity. The proportion of biofilm-positive/icaD-positive versus biofilm-positive/icaD-negative strains was 9:0 and 9:0 (81.8%) by the TA and CRA, which clearly indicates that icaD was a more reliable gene to be accounted for in the biofilm formation. MDCK recorded a higher proportion than that recorded by the CRA and TA results (MDCK-positive/icaD-positive versus MDCK-positive/icaD-negative 10:0, 90.9%). Evaluation of the ica operon, CRA plate test, TA, and MDCK can contribute to the high clinical impact in the management of antibiotic therapy, in infections associated with devices in veterinary medicine, the dairy industry, and food processing.

Background and Aim: Lumpy skin disease (LSD), is a highly infectious viral disease of cattle, caused by LSD virus (LSDV) which belongs to the genus Capripoxvirus of family Poxviridae. In the summer of 2017, skin lesions suggestive of LSD were observed in cattle at several governorates in Egypt. This study aimed to detect LSDV in cattle specimens using rapid serological and molecular diagnostic assays. Materials and Methods: A total of 46 skin biopsies and uncoagulated blood samples were collected from cattle with LSD suggestive clinical signs, as well as 290 coagulated whole blood samples from cattle without skin lesion in different governorates in Egypt during the summer of 2017. Skin biopsies were used for virus isolation from the chorioallantoic membrane of 11-day-old specific pathogen-free embryonated chicken eggs (SPF-ECEs). LSDV was identified using conventional polymerase chain reaction (PCR), real-time PCR (RT-PCR), and fluorescent antibody technique (FAT) with specific hyperimmune serum against LSDV. Cattle sera were examined using indirect FAT (IFAT) and indirect enzyme-linked immunosorbent assay (ELISA). Results: Skin nodules and sitfast lesions were significant clinical signs observed in all LSD suspect cattle. SPF-ECEs, from which positive isolations were made and it showed characteristic inflammatory and focal white pock lesions. The isolated viruses were identified as LSDV by FAT, conventional gel-based PCR, and RT-PCR. Among the skin biopsies and corresponding blood samples, LSDV-positive samples percentage were 39.13 and 36.95 by RT-PCR, followed 34.78 and 28.26 by conventional PCR and then 32.6 and 26.8 by FAT, respectively. The total positive percentage of LSDV antibody detected in cattle serum samples were 17.93 and 14.48 by indirect ELISA and IFAT. Conclusion: LSDV was detected and identified in skin biopsies and corresponding blood samples of naturally infected cattle, more LSDV-positive samples were detected by RT-PCR, followed by conventional PCR and then FAT. The indirect ELISA detected more antibody-positive samples than the IFAT from cattle serum samples. The RT-PCR assay is simple, sensitive, rapid, and reliable for the detection of LSDV in blood and skin nodule biopsies of suspected cattle.

The aim of this study was to examine the genetically mediated antimicrobial resistance in 94 coagulase-negative staphylococcal (CNS) milk isolates (buffalo, n = 88, and cow, n = 6), and to determine whether antimicrobial resistance profiles differed between bacterial species. Our analysis of 94 CNS isolates from milk confirmed the well-established multiresistant character of staphylococci in the dairy setting. Resistance against oxacillin, ciprofloxacin and cefoxitin was most frequently observed. Eleven CNS species isolated from buffalo's and cow's milk samples were 100% sensitive to gentamicin, erythromycin, clindamycin and ciprofloxacin. Resistance to oxacillin was attributed to the mecA gene in 44.7% of the oxacillin-resistant isolates. The mecA gene was detected in Staphylococcus intermedius, epidermidis, hominis, hyicus, caprae, sciuri, lugdunensis and xylosus while totally absent in chromogenes, simulans and lentus. Of the 11 CNS species, S. epidermidis, S. lugdunensis, S. hominis, S. xylosus and S. intermedius were the only species that exhibited multiple resistance.

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.

No abstract