MRSA

Syn ORSA / CRSA

Introduction• Any strain of S. Aureus that has developed resistance to Beta-Lactam

Antibiotics

• Natural Selection

• No change in Virulence ; ‘Difficult-to-treat’

• HA vs CA

• Known since 1963 ; Outbreak investigation by CDC in LA County Prison in 2001

• Commonly colonizes Ant Nares, Respiratory Tract, Urinary Tract, open wounds, IV catheters

Genetic Basis for Resistance

Acquisition of Extrachromosomal Genetic Elements via Plasmids, TGEs in MSSA of :

– mecA (Resistance Genes for Transpeptidases)

– SCCmec (Genomic Island / Staphylococcal Cassette Chromosome)

– ACME (Virulence factor / Arginine Catabolic Mobile Element)

– Strains : EMRSA15/16 & ST5/250 MRSA I-IV

Predisposition• Hospitals (Nosocomial)

– Open wounds– Invasive devices– Immunocompromised indls– Diabetics– Institutionalization

• Prisons

• Old-age homes / Orphanages

• Children

• Contact & Team Sports (‘Turf Burns’ / Shared Eq)

• IVDUs

• Unregulated Antibiotic usage (esp Quinolones)

• Veterinarians, livestock handlers (CC398 var), and pet owners

Clinical Features

• Preceding Prodromal / Constitutional symptoms

• Small Papules / Superficial Folliculitis / Impetigo resembling IBR painful , deeper lesions viz Carbunculosis, Abscess, Cellulitis

• 75% CA-MRSA + HA-MRSA - skin and soft tissue

• 25% highly virulent strains predominantly can cause Septicemia, TSS, Necrotizing Fasciitis, Pyomyositis, Necrotizing Pneumonia, IE, Osteomyelitis, Septic Arthritis

• Toxin-mediated (Panton-Van Leukocidin PVL, Hemolysin Gamma Hig, Phenol Soluble Modulin PSM)

• a

• aa

• aa

Diagnosis

• Clinical (High index of suspicion)

• Culture (Blood / Sputum / Pus )

• NAATs (PCRs / LCRs / TMA / bDNA)

• Latex Agglutination Test for PBP2a imparts the ability of S. aureus to be resistant to oxacillin

TreatmentCA-MRSA > HA-MRSA (S)

• SULPHA DRUGS (SEPTRAN)

• TETRACYCLINES (DOXYCYCLINES)

• LINCOSAMIDES (CLINDAMYCIN)

• GLYCOPEPTIDES (VANCOMYCIN / TEICOPLANIN) VISA

• OXAZOLIDINONES (LINEZOLID)

• PRISTINAMYCINS (QUINPRISTIN+DALFOPRISTIN)

• LIPOPEPTIDES (DAPTOMYCIN)

• GLYCYLCLINES (TIGICYCLINE)

RESEARCH / EXPERIMENTAL

• Antibiotics under trial :TELAVANCIN, DALBAVANCIN, CEFTAROLENE, CEFTABAPROLENE,

TOREZOLID, NEMONOXACIN

• PLATENSIMYCIN , a natural antibiotic, under investigation 2006 ; from Streptomyces)

• Medical grade Honey viz ULMO 90 / MANUKA 25 tried in 2010 (activity of hydrogen peroxide, methylglyoxal, and a novel compound named Bee Defensin-1)

• Ocean-dwelling living sponges produce compounds make MRSA more susceptible to antibiotics

• Semi-toxic fungi/mushrooms excrete broad spectrum antibiotics– The psychedelic mushroom Psilocybe Semilanteacae has

been shown to strongly inhibit the growth of Staphylococcus aureus

• Cannabinoids– Cannabidiol (CBD) Tetrahydrocannabinol (THC)– Cannabinol (CBN), Cannabichromene (CBC)

• Phage therapy

• MDT

Prevention

• Screening (Nasal Cultures)

• Hand-Washing / Good hygiene

• Surface Sanitization

• Copper Coating (C11000 / C19700 / C4400)

• Biomedical Waste Management

• Restricted Antibiotic Usage

• Decolonization (04-Point-Technique)

THANK YOU