Virulence Factors in Methicillin-Resistant <i>Staphylococcus aureus</i> Isolated from ICU Units in Brazil

Abstract

Species of Staphylococcus are common in hospital infection (HI). Methicillin resistant S. aureus(MRSA) has also become a serious problem in Brazilian HI. The aim of this study was to characterize the pathogenicity of methicillin-resistant S. aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) isolated in public hospitals. The clinical isolates were obtained from intensive care unit. The MRSA and MSSA strains were genotyped by PCR for detection genes related to virulence factors. Moreover, the strains were tested for biofilm formation and cytokine induction in macrophages. Three strains of MRSA (9.68%) expressed the Sea gene, one (3.23%) Seb, 17 (54.84%) Spa and seven (22.58%) had PVL. Two MSSA strains (2.98%) expressed the Sea gene, three (4.48%) Seb, 18 (26.87%) Spa and 11 (16.42%) showed positive results for the PVL gene. There was no expression of Sec and CflA between MRSA and MSSA strains. Among MRSA and MSSA isolates, none statistical differences were observed in biofilm production. The analysis of cytokine induction in the inflammatory response of J774 macrophages by MRSA and MSSA isolates did not show statistical difference. Understanding the mechanisms of pathogenesis of S. aureus could provide important clues for both preventing and treating infection caused by these organisms.

<b>Distinct strains of <i>Staphylococcus aureus</i> lead to different inflammatory response patterns in a murine model of intradermal infection

“…Preview studies have shown that MRSA strains have more virulence genes than MSSA strains, which can explain the higher intensity of the inflammatory response developed by the MRSA strain (Lim, Yeo, Suhaili, & Thong, 2012). Moreover, the MRSA strain studied in this paper was analyzed and its virulence factors were identified as Spa, PVL and Sea genes as well as it is a strong producer of biofilm (Souza et al, 2014). Figure 1.…”

Methicillin-Resistant Staphylococcus Aureus (MRSA): Prevalence and Antimicrobial Sensitivity Pattern among Outdoor and Indoor Patients Dhaka City Hospital, Bangladesh

“…14 (1.45%), as well as we were not identified (no growth) 797 (82.67%) ( Fig. 2 and Table 3) [17][18][19].…”

“…Science 1960s, S. aureus initially described, on the other hand, S. aureus, is principally amalgamated with skin, skin glands and mucous membrane of warmblooded animals so an adaptable microbe as well as a frequent invader of animals, and humans [3]. The organism is favour nosocomial bacteria implicate with several infections, including pneumonia, septic arthritis, osteomyelitis, endocarditis, toxic-shock syndrome and food poisoning [4][5][6][7]. Many scientists are of the opinion that, (healthcare associated methicillinresistant S. aureus, HA-MRSA), the burden of MRSA colonisation and infection has recently enlarged to further ecological slot [8].…”

The Production of Biofilm from Methicillin Resistant Staphylococcus Aureus Isolated from Post-Surgical Operation Inflammation

“…The results as shown in Figure 2 that revealed the sixty-eight isolates were 100% resistant to Cefotaxime while 97% of isolates were resistant to Oxacillin which considers the alternative antibiotic of methicillin and in detection of MRSA isolates according to the recommendation of [18].The resistance of isolates for remaining antibiotics were; Ceftriaxone 99%, Cefipime 97%, Cefoxitin and ampicillin 87% , Penicillin79%, Nalidixicacid 75%, erythromycin 65 , azithromycin 43% , ciprofloxacin 26% ,trimethoprim 25% , vancomycin and gentamycin 19% , Meropenem 18% , Rifampin 15% ,Trimethoprim-sulfamethoxazole 13% , doxycycline 10% , clindamycin 9%, chloramphenicol 6% , amikacin 4% ,while all 68 isolates were sensitive to Nitrofurantoin. The results of antibiotic sensitivity showed high resistance of isolates to β-1000bp 500bp 276bp lactam antibiotics this resistance may due to the presence of β-lactamase enzymes ( that are involved in bacterial resistance to beta-lactam antibiotics) that hydrolyzed the β-lactam ring and inactivating the antibiotic [32] or due to the expression of mecA gene or blaZ gene that produced by S.aureus isolates or other alternative mechanisms [33]. Results of the current study showed that all S.aureus isolates have resistance to at least 8 antibiotics of different groups(MDR) that corresponds with the study of [34] and [35] were approved the multiple drug resistance of clinical isolates of S.aureus in Baghdad in percentage 100%, while [36] reported that 61% of clinical isolates were multiple drug resistance (MDR).…”