Emergence Of Methicillin-resistant Strains Research Articles

Portulaca oleracea L. organic acid extract inhibits persistent methicillin-resistant Staphylococcus aureus in vitro and in vivo.

Staphylococcus aureus continues to be one of the most important pathogens capable of causing a wide range of infections in different sites of the body in humans and livestock. With the emergence of methicillin-resistant strains and the introduction of strict laws on antibiotic usage in animals, antibiotic replacement therapy has become increasingly popular. Previous studies have shown that Portulaca oleracea L. extract exerts a certain degree of bacteriostatic effect, although the active ingredients are unknown. In the present study, the antibacterial activity of the organic acid of P. oleracea (OAPO) against S. aureus was examined using a series of experiments, including the minimum inhibitory concentration, growth curve, and bacteriostasis curve. In vitro antibacterial mechanisms were evaluated based on the integrity and permeability of the cell wall and membrane, scanning electron microscopy, and soluble protein content. A mouse skin wound recovery model was used to verify the antibacterial effects of OAPO on S. aureus in vivo. The results showed that OAPO not only improved skin wound recovery but also decreased the bacterial load in skin wounds. Moreover, the number of inflammatory cells and cytokines decreased in the OAPO-treated groups. In summary, this study reports a botanical extract that can inhibit S. aureus in vitro and in vivo, indicating the potential use of OAPO to prevent and control S. aureus infection in the near future.

210 Eosinophil-derived IL-17 protects against epicutaneous Staphylococcus aureus infections

Staphylococcus aureus is the predominant cause of skin and soft tissue infections in humans and with the emergence of methicillin-resistant strains, has prompted the need for alternatives to antibiotics through a better understanding of host immune responses. IL-17-mediated immunity is crucial for host defense against S. aureus skin infections, but the immune cells involved are not entirely defined. Recently, eosinophils were identified to produce IL-17 during fungal infections. However, the role of eosinophils in IL-17-mediated immunity against S. aureus skin infections is unexplored. To investigate the role of eosinophils against S. aureus skin infections, wildtype (wt) and eosinophil-deficient mice were epicutaneously exposed to a bioluminescent strain of S. aureus and bacterial burden monitored over time. Eosinophil-deficient mice had increased bacterial burden compared to wt mice, suggesting that eosinophils contributed to host defense against S. aureus. Next, we used an IL-17A-tdTomato x IL-17F-GFP dual reporter mouse with flow cytometry to determine whether eosinophils produced IL-17A or IL-17F during S. aureus infection. Interestingly, ∼50% of IL-17A-producing cells in the S. aureus-exposed skin were eosinophils, whereas eosinophils did not produce IL-17F. To test whether eosinophil-derived IL-17 protects against S. aureus skin infections, eosinophils were adoptively transferred into IL-17A/F-deficient mice treated with neutralizing mAb against IL-17A+F or an isotype control. Indeed, eosinophils restored the host defense defect in IL-17A/F-deficient mice, but not in the presence of IL-17A+F mAbs, indicating that eosinophil-derived IL-17 promoted host defense. Taken together, we uncovered a novel mechanism whereby eosinophil-derived IL-17 protects against S. aureus skin infections, which has implications in the development of immune-based therapies against S. aureus and potentially other skin infections.

Prevalence and Factors Associated with Wound Colonisation by Staphylococcus Species at Tertiary Care Hospital: A Cross-sectional Study

Introduction: The Staphylococcus species do not directly cause infection but invade an already existing wound and causing extensive tissue necrosis and enlarging an already existing wound. The human host factor plays a major role in the pathogenesis by making a suitable environment for pathogens, like diabetic mellitus, hypertension, and so on. The emergence of methicillin resistant strains worsens the clinical output and very few therapeutic alternatives are left to treat such infections. Aim: The present study was attempted to see the relation of Staphylococcus species with host factors among wound infections. Materials and Methods: The specimens taken from various types of wound infection were screened for Staphylococcusspecies as per standard microbiological guidelines. The clinical history of the patients were taken from the ‘patient’s case record form’ and Medical Record Department (MRD) section. The data was statistically analysed, p-value ≤0.05 was considered significant. Results: A total of 421 Staphylococcus species were isolated from various clinical samples, out of which 159 (37.7%) were isolated from wound infections. Of which 142 (89.3%) were S.aureus and 17 (10.7%) were S.epidermidis. Diabetic mellitus 29 (18.2%) and hypertension 11 (7%) were found to be a major host factor facilitating the infection. Methicillin Resistant Staphylococcus aureus (MRSA) was 100 (62.9%) while Methicillin Resistant Staphylococcus epidermidis (MRSE) was not found in the single strain. Inducible clindamycin resistant strains among wound infection were found to be 58 (36.5%). Conclusion: Staphylococcal wound infections should be carefully treated to prevent microbial spread especially in immune-compromised patients, better patient recovery, and reducing healthcare costs.

Biofilm-Forming Methicillin-Resistant Staphylococcus aureus Survive in Kupffer Cells and Exhibit High Virulence in Mice.

Although Staphylococcus aureus is part of the normal body flora, heavy usage of antibiotics has resulted in the emergence of methicillin-resistant strains (MRSA). MRSA can form biofilms and cause indwelling foreign body infections, bacteremia, soft tissue infections, endocarditis, and osteomyelitis. Using an in vitro assay, we screened 173 clinical blood isolates of MRSA and selected 20 high-biofilm formers (H-BF) and low-biofilm formers (L-BF). These were intravenously administered to mice and the general condition of mice, the distribution of bacteria, and biofilm in the liver, lung, spleen, and kidney were investigated. MRSA count was the highest in the liver, especially within Kupffer cells, which were positive for acid polysaccharides that are associated with intracellular biofilm. After 24 h, the general condition of the mice worsened significantly in the H-BF group. In the liver, bacterial deposition and aggregation and the biofilm-forming spot number were all significantly greater for H-BF group than for L-BF. CFU analysis revealed that bacteria in the H-BF group survived for long periods in the liver. These results indicate that the biofilm-forming ability of MRSA is a crucial factor for intracellular persistence, which could lead to chronic infections.

A Review on Community Acquired Methicillin Resistant Staphylococcus aureus an Emerging Infectious Disease

Methicillin resistant Staphylococcus aureus (MRSA) has emerged as a community acquired infection in the past decade. Molecular studies showed that HCA-MRSA and CA-MRSA represent different organisms that produced different clinical syndromes .MRSA infection is associated with high morbidity, mortality, longer hospital stay and economic burden worldwide. All over the world, the dissemination of a few distinct clones of CA-MRSA has resulted in an increase in skin and soft tissue infections and necrotizing pneumonia, without defined risk factors. There has been link to fluroquinolone (FQ) exposure to epidemic CA-MRSA strains obtained from subjects with nasal colonization. Low socioeconomic status may be one common link among the identified high-risk groups, although many patients with CA-MRSA infections have no risk factor. CA-MRSA isolates are characterized by the presence of SCCmec type IV or type V. S.aureus clones ST30, ST80, CC75 and ST 93 has been documented in some countries. These clones are likely to provide insights into the emergence of methicillin resistant strains of S.aureus. CA-MRSA is readily disseminated in the hospitals and may cause outbreaks of infection .It is suggested that the use of the few effective antibiotic agent should be restricted

Population Genetic Structure of the Staphylococcus intermedius Group: Insights into agr Diversification and the Emergence of Methicillin-Resistant Strains

Population Genetic Structure of the <i>Staphylococcus intermedius</i> Group: Insights into <i>agr</i> Diversification and the Emergence of Methicillin-Resistant Strains

Glycopeptide resistance in gram-positive pathogens.

The rapid emergence of vancomycin-resistant enterococci as significant nosocomial pathogens during the 1990’s has dramatically influenced our awareness of the threat posed by drug resistant microorganisms. Vancomycin was first introduced in the 1960’s, but it’s use was initially limited due to concerns regarding toxicity until the emergence of methicillin resistant strains of staphylococci during the 1980’s. By the late 1980’s, vancomycin was frequently the only reliable therapeutic alternative for nosocomial staphylococcal infections, and both appropriate and inappropriate usage mushroomed. At Thomas Jefferson University Hospital in Philadelphia, annual parenteral vancomycin usage increased from 6 kg/year in 1986 to over 20 kg/year in 1990. Although a number of unusual organisms such as Leuconostoc, Pediococcus and Lactobacillus spp. have long been known to be resistant to vancomycin, these have primarily been laboratory curiosities and have never posed a major clinical problem. However, the appearance of acquired vancomycin resistance in the clinically important pathogen Enterococcus was not anticipated.