Evaluation of Methicillin-Resistance Rates among Community-associated Staphylococcus aureus Infections in Korean Military Personnel

Prevalence of Selected Immune Evasion Genes and Clonal Diversity in Methicillin-Susceptible Staphylococcus aureus Isolated from Nasal Carriers and Outpatients with Cut Wound Infections

Staphylococcus aureus, being one of the most common human pathogens, is responsible for infections in both hospital and community settings. Its virulence is attributed to its ability to evade the immune system by producing immune evasion (IE) proteins. The aim of this study was to detect the frequency of selected IE genes (spin, sbi, sea, sak, chp, scin, sep, ecb), belonging to the immune evasion cluster (IEC), and IEC types in 86 methicillin-susceptible S. aureus (MSSA) strains isolated from unrelated outpatients. In order to determine the diversity of analyzed strains, the phylogenetic relatedness was also determined. All strains were examined for the presence of IE genes using polymerase chain reaction assay. To analyze the clonal relatedness of S. aureus, pulsed-field gel electrophoresis (PFGE) was performed. All analyzed strains harbored the scn gene, followed by sbi (95.4%), ecb (91.7%), spin (89.5%), sak (83.7%), chp (67.4%), sep (67.4%) and sea (5.8%). Seventy-three (84.9%) S. aureus strains were classified into IEC types, of which, IEC type F was most commonly observed. IEC type A was not detected. PFGE results showed no association between clonal relatedness and the presence of IE genes/IEC types. In conclusion, the abundant and so diverse repertoire of genes determining invasion in analyzed strains may prove the fact that these strains are highly advanced and adapted to evade the host immune response.

Prevalence pattern of MRSA from a rural medical college of North India: A cause of concern

Introduction:

Methicillin-resistant Staphylococcus aureus (MRSA) has become a global challenge. The shift of this organism form hospital settings to community setting and increasing resistance to non-β-lactams antibiotics have further aggravated the crisis. This trend in MRSA has necessitated the knowledge and sensitization about this agent among physicians in rural and peripheral settings.

Material and Methods:

Present study was undertaken at Department of Microbiology at rural medical college of North India from January 2017 to December 2019 (3 years). All the clinical samples collected with aseptic precautions were processed as per standard protocol. All the Staphylococcus aureus isolates cultured were subjected to antimicrobial susceptibility testing as per CLSI guidelines 2019. Screening for MRSA was done by CLSI recommended methods, such as cefoxitin disc (30 μg), oxacillin disc (1 μg), and oxacillin screen agar as per CLSI recommendation.

Results:

A steady increase in number of MRSA isolates was observed from year 2017 to 2019 with overall prevalence being 33.7%. Most MRSA isolates were obtained from pus samples. Cefoxitin disc diffusion method is a dependable detection method compared to oxacillin disc diffusion and oxacillin screen agar for identification of MRSA.

Conclusion:

The rising trend of MRSA impresses upon the acute need of stringent infection control practices namely strict compliance to hand hygiene, prevention of misuse and overuse of antibiotics and a continuous surveillance program for MRSA. Also sensitization about this agent among the primary health physician is the need of hour to implement the control measures and limit its spread in communities.