Online ISSN: 2515-8260

Keywords : virulence factors

Staphylococcus aureus: An Overview of Discovery, Characteristics, Epidemiology, Virulence Factors and Antimicrobial Sensitivity

Narin A Rasheed; Nawfal R Hussein

European Journal of Molecular & Clinical Medicine, 2021, Volume 8, Issue 3, Pages 1160-1183

Staphylococcus aureus is an important infectious pathogen in health sector and communities. S. aureus was first described by the Scottish surgeon Alexander Ogaston in surgical abscess in 1881. It causes various infections ranged between simple to life threating infections. Owing potent toxins and other virulence factors enabled the bacteria to be very virulent. Additionally, acquisition of antimicrobial resistant genes increased the challenge in treating the infections caused by bacteria especially methicillin resistant S. aureus strains (MRSA) that are often multidrug resistant strains. The circulation of MRSA between health settings and communities resulted in changing even the genetic map for the strains in both places. Vancomycin was used for years and still acts as the drug of choice for treating MRSA infections but recently the resistance to vancomycin has risen and vancomycin resistant S. aureus were recorded. Consequently, different regimes were used like combination of antibiotics to reduce the resistance rate to antibiotics if they were used as a single drug and practiced the control measures at health settings to reduce the spread of MRSA strains. At last, global health organizations call for research and finding new antibiotics agents and put MRSA on the top list of infectious agents that need more antibiotics.


Hala Mohammed Majeed; Bashar Sadeq Noomi; Marwan Q. AL-Samarraie

European Journal of Molecular & Clinical Medicine, 2020, Volume 7, Issue 9, Pages 68-74

Enterococcus faecalis form an important population of commensal bacteria and have been reported to possess numerous virulence factors considered significantly important in exacerbating diseases caused by them. Objectives: The present study was conducted to evaluates the presence of virulence factors and antibiotic susceptibility among Enterococcus faecalis isolated from sheep. Methods: The study included the collection of 50 samples (25 Milk samples collected from the udder was washed and the teats were disinfected and dried using alcohol, the first milk drop removed. 5ml of milk collected on aseptic tube and 25 Feces samples collected from sheep diarrhea from rectal by aseptic gloves. (from October 2018 to March 2019 ) and transported to laboratory as soon as possible in sterile Brain heart infusion broth that incubated at 37 C for at least 24-28 hours to increasing chances of isolation. Enterococcus faecalis that were recognized by cultural characteristics, Gram stain, and biochemical reactions. Results: The results of the laboratory cultural of 50 cotton swabs used s show that the isolation rate of Enterococcus spp. were 32% and 56% from milk and feaces respectively. the result of PCR test for detection of Enterococcus faecalis: show that the Enterococcus faecalis detected in rate of 66.6% from total Enterococcus spp. While the result of Enterococcus faecalis virulence factors showed that the Surface proteins, Gelatinase and Hemolysin were 75%, 33.3%, 25.5% respectively. Results of antibiotic sensitivity test showed the most bacterial isolated sensitive Nitrofurantoin , Imipenem and Nalidixic acid were 91.6%,83.3% and 58.3% % respectively Conclusion: We report that our simple modification of the existing multiplex PCR had increased the detection of the enterococcal virulence genes. Predominance of virulence genes was in order of Surface proteins, Gelatinase and Hemolysin were 75%, 33.3%, 25.5%. This modified PCR protocol could be useful to resolve the problem of decreased detection of virulence determinants in enterococci.

Study Of Some Virulence Factors And Virulence Genes Produced By Gram (+Ve) And Gram (-Ve) Cocci Isolated From Clinical Samples In Al-Anbar Province/Iraq

Rawaa Turki Abdul Ghafoor; Asst. prof. Hana Abdel Latif Yassin

European Journal of Molecular & Clinical Medicine, 2020, Volume 7, Issue 9, Pages 535-547

This study aimed to isolate the G (+ve) and G(-ve) cocci from different clinical samples and study some virulence factors and virulence genes produced by them .
In this study, (177) samples were collected from different clinical sources, including (49) blood samples, (43) urine samples, (30) pus swabs, (40) cervical swabs and (15) sputum samples from patients attending Ramadi Teaching Hospital for Maternity and Children, Ramadi Teaching Hospital in Ramadi in Al-Anbar province/Iraq during the period from 19/12/2018 to 12/5/2019, and (203) isolates were identified as Gram (+ve) and Gram (-ve) bacteria, then (166) Gram (+ve) and Gram (-ve) cocci were chosen as study samples.
After diagnosis of the isolates, results of Gram staining showed that the highest number and percentage of Gram positive and Gram negative bacteria were from urine samples 48(28.9%) followed by blood samples 44(26.5%) then pus swab and cervical isolates 37(22.3%) and 23(13.9%) respectively, while the lowest number and percentage of isolates were from sputum 14(8.4%). Staphylococcus aureus showed the highest number and percentage of isolates 48(28.9%). For gram (-ve) cocci, only (10.4%) of Neisseria gonorrhea was isolated from urine samples and (14.2%) of Moraxella catarrhalis was isolated from sputum samples
Regarding virulence factor production, the hemolysin producer isolates were the highest 103(62.04%), and results of hemolysin producing bacteria was S.aureus, S.hominis, S.haemolyticus, S.chromogenes, S.xylosu and S.warneri showed (100%) beta hemolysis, while only one isolate of the genus Micrococcus was beta-hemolytic all isolates of Streptococcus pyogenes and Streptococcus agalactiae showed (100%) beta hemolysis (β), whereas the isolates of Strept. pneumoniae, Aerococcus urinae and Aerococcus viridans showed (100%) partial or alpha (α) type hemolysis, and (8) isolates of E.faecalis showed complete hemolysis (β-haemolysis).
All S. aureus isolates were (100%) gelatinase producers Kocuria kristinae was (100%) producer, all Strep. pyogenes, Strep. Agalactiae, Strep. Anginosus, Strep. Lc. lactis lactis and Strep.mitis isolates showed (100%) ability to produce this enzyme, The (24) isolates of the genus Enterococcus bacteria were (100%) able to produce the enzyme gelatinize, including (19) E.faecalis isolates and (5) E. faecium. As for the genus Gram (-ve) cocci, two isolates of Moraxella catarrhalis showed (100%) ability to produce the gelatinase enzyme.
The number and percentage of urease enzyme producers were 49(29.51%), where 38(79.16%) of S.aureus isolates were able to produce it. Also, 3(17.64%) of S.hominis isolates were able to produce it, while only one isolate of S.lentus (20%) was able to produce it. Moreover, both S.xylosus and S.warneri isolates were (100%) urease-producers.
From the total (166) isolates, 20(12.04%) isolates formed biofilms. E.faecalis bacteria was the most biofilm-producing isolate 9(47.36%), followed by S.aureus bacteria 3(6.25%) then
S. lentus isolates (40%), while Kocuria rosea bacteria produced biofilm as 1(100%), Strep.pneumoniae and Strep.pyogenes produced as 1( 25%) for each isolate, and 1(50%) for Strep. anginosus isolate, whereas Strep.salivarius and Strep.mitis produced biofilm as 1(100%) isolate for each of them.
Also (100%) of the virulence genes icaC, srtC, and Emm were detected in S.aureus, E.faecalis and Strep.pyogenes isolates, which produced strong, moderate and weak biofilm types by using the PCR technology.