Abstract
One of the most important pathogens that threaten human health all over the world is Staphylococcus spp. characterization and identification of such pathogen considers a useful tool to control of some serious problems resulting by these bacteria. Therefore one hundred and twenty samples including blood, urine, abscess, semen, pus, sputum, ears, vaginal and spit swabs were collected from patients of Tanta University Hospital and outpatient clinics. A total of 126 Gram positive bacterial isolates were obtained from these clinical specimens. Of these isolates 107 bacterial strains were identified as Staphylococcus spp and 15 strains identified as Streptococcus spp in addition to 4 strains were identified as Enterococcus spp, preliminary identification was conducted on the basis of colony characteristics such as Gram staining, pigment production, hemolysis, catalase activity, coagulase test and fermentation of manitol sugar. Out of these strains, 30.95% have the potency to make alpha hemolysis while 30.95% have the ability to make beta hemolysis and 38.09% posse the capacity to make gamma hemolysis on blood agar medium. Beta hemolysis Staphylococcus spp were selected for study of some virulence factors on basis of coagulase production in which 17.24% of Staphylococcus spp were coagulase positive and 82.76% were coagulase negative Staphylococcus spp. Studying the susceptibility pattern of these strains to some commercial antibiotics was carried out. Further future studies are recommended to investigate the effect of some natural compounds on gene regulation that responsible for hemolysis process.
Highlights
One of the most important Gram positive medical bacteria is Staphylococcus aureus
A total of 126 gram positive bacterial isolates were obtained from several clinical specimens that collected from different sources
Of these isolates 107 (85%) bacterial strains were preliminary identified as Staphylococcus spp and 15 (12%) strains identified as Streptococcus spp in addition to 4 (3%) strains were identified as Enterococcus spp
Summary
One of the most important Gram positive medical bacteria is Staphylococcus aureus. Its opportunistic pathogens for human and animal responsible for fatal disease like nosocomial and community-associated infections which make high morbidity and mortality rate. S. aureus appear as large yellow or white colonies on nutrient rich agar media This pathogen can produce carotenoid pigments which imparts the yellow color on its colonies, so the term aureus refers to Latin word the color of gold. This yellow pigments act as antioxidant that protect this strain from the host’s immune system. The medical importance of this strain is due to production of virulence factors, surface proteins, enzymes, toxins and biofilm formation in addition to rapid development of drug resistance (Abu-elghait 2016)-Bacterial resistance to antibiotics is an issue that has led to the search for new antibacterial approaches. Drugs targeting virulence is an alternative approach to treat infections with resistant bacteria (Escaich, 2008)
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