mrsa

MANAGEMENT AND PREVENTION OF MRSA : 

MANAGEMENT AND PREVENTION OF MRSA Dr H.R.V.Rajkumar Consultant Microbiologist & Director – Lab Services Kamineni Hospitals Ltd, L B Nagar, Hyderabad.

MRSA : 

MRSA Methicillin-resistant Staphylococcus aureus. Methicillin resistance implies resistance to all penicillins, cephalosporins, carbapenems and beta lactam/beta lactamase inhibitor combinations such as ampicillin/sulbactam, amoxycillin/clavulanic acid, piperacillin/tazotactam, and ticarcillin/clavulanic acid regardless of the in vitro test results.

MRSA : 

MRSA Hospital associated MRSA isolates often are multiply resistant to other commonly used antimicrobial agents, including erythromycin, clindamycin and tetracycline. Community associated MRSA isolates are often resistant only to beta lactam agents and erythromycin

Why are MRSA important? : 

Why are MRSA important? Pathogenicity Limited treatment options MRSA are transmissible Some strains of MRSA – known as epidemic strains or EMRSA – are more easily spread. 16 epidemic strains are identified and the commonest to affect hospitals are EMRSA-15 and EMRSA-16.

Testing for MRSA (Recommendations of CLSI) : 

Testing for MRSA (Recommendations of CLSI) Oxacillin disc diffusion test (using 1µg of oxacillin disc) Oxacillin MIC tests Cefoxitin disc diffusion test Latex agglutination test for PBP 2a (Rapid method) mec A gene - PCR

CLSI breakpoints for S.aureus and CONS : 

CLSI breakpoints for S.aureus and CONS INTERPRETIVE CRITERIA (in µg/ml) FOR OXACILLIN MIC TESTS INTERPRETIVE CRITERIA (in mm) FOR OXACILLIN DISK DIFFUSION TESTS INTERPRETIVE CRITERIA (in mm) FOR CEFOXITIN DISK DIFFUSION TEST

Why oxacillin and cefoxitin tested instead of methicillin : 

Why oxacillin and cefoxitin tested instead of methicillin Oxacillin maintains its activity during storage better than methicillin Oxacillin detects heteroresistant strains better than methicillin Cefoxitin is an better inducer of the mecA gene and disk diffusion tests using cefoxitin gives clearer endpoints and are easier to read than tests with oxacillin.

CONTROL OF MRSA : 

CONTROL OF MRSA

Slide 9: 

“Relax – MRSA will get you before the Swine flu”

Screening of patients for MRSA : 

Screening of patients for MRSA Swabs from nose, lesions or wounds, manipulated sites, intravenous and stoma sites, tracheostomies, perineum/groin, urine from catheterized patients and sputum if available. Other specimens include – umbilicus in infants, faeces and vaginal swabs, axilla and skin of the buttock area in the elderly.

Carriage of MRSA by HCWs : 

Carriage of MRSA by HCWs Transient carriage – when the MRSA can be isolated from staff noses or fingers after duty but not before their next day’s duty. Most important mode of spread of MRSA Short term nasal carriage – Where MRSA carriage can be detected on two consecutive screens Persistent nasal carriage

Treatment of carriers : 

Treatment of carriers Nasal carriage Mupirocin (paraffin base) applied to the anterior nares 3 times daily for 5-7 days. Prolonged application should be avoided. Strains of MRSA with low level (MIC 8-256 mg/l) and high level (>256 mg/l) mupirocin resistance are already emerging. At least one month should elapse before repeating a course of mupirocin treatment of skin infections

Treatment of carriers : 

Treatment of carriers Nasal carriage Other topical agents include – 1% chlorhexidine or 0.5% neomycin Systemic therapy with rifampicin in exceptional circumstances along with other antibiotics. Difficult to distinguish failure to eradicate MRSA from re-colonization with the same strain.

Treatment of carriers : 

Treatment of carriers Intact skin Daily bathing for 3 consecutive days with chlorhexidine, hexachlorophane, triclosan or povidone-iodine detergents. Direct application of the antiseptic detergent to the skin is more effective in reducing skin colonization than adding concentrates to bath water. Hexachlorophane powder can be applied to the axillae and groin of adults if these are colonized

Treatment of carriers : 

Treatment of carriers Skin lesions Mupirocin in a polyethylene glycol base – applied to skin lesions such as eczema and small superficial pressure sores. Should not be used on large burns or large raw areas because PEG is nephrotoxic and may be absorbed. Mupirocin in a paraffin base can be used instead. Murpirocin ointment is not suitable for the insertion sites of central venous catheters or other plastic devices because PEG may cause damage to catheter material.

Systemic treatment of infections : 

Systemic treatment of infections Glycopeptides Vancomycin Highly purified and less toxic preparations are available Although used in clinical practice vancomycin/aminoglycoside combinations do not have proved synergy for both MRSA and MSSA. Poor penetration through meninges.

Systemic treatment of infections : 

Systemic treatment of infections Glycopeptides Teicoplanin Greater lipophilicity than vancomycin Linezolid Active against MRSA, VRE and PRSP Effective orally Blood counts should be monitored

Systemic treatment of infections : 

Systemic treatment of infections Rifampicin Useful in CNS infections, Bone infections and Endocarditis. Should always be used with other anti staphylococcal agents and should never be used alone. Beta lactam/BLI combinations (Augmentin, Pip+Taz) Not effective against MRSA

Systemic treatment of infections : 

Systemic treatment of infections Quinupristin/dalfopristin Derived from the streptogramins pristinamycin IA and IIB Belong to the family of macrolides-lincosamides-streptogramins The drugs are present in a fixed 30:70 ratio and are synergistic. Other newer agents Daptomycin, LY333328 (glycopeptide) and semi synthetic tetracyclines (glycylcylines)

Emerging threats : 

Emerging threats Vancomycin-Intermediate Staphylococcus aureus (VISA) First reported from Japan 1997 and later from USA and other countries. Have reduced susceptibility to vancomycin (MIC 4-8 µg/ml) All strains of S.aureus with vancomycin MIC of ≥ 4 µg/ml should be considered candidate strains for VISA. Disc diffusion test should not be used to detect vancomycin susceptibility and instead E test should be used. Vancomycin-resistant Staphylococcus aureus (VRSA) First reported in the USA in Michigan in July 2002. MIC ≥ 32 µg/ml. Heteroresistant strains are already emerging.

Standard infection control precautions for MRSA : 

Standard infection control precautions for MRSA Cover all cuts, abrasions and lesions – especially those on hands and forearms – with a water proof dressing Maintain hand hygeine Soap and water are usually adequate Alcohol hand rub can be used instead if hands are socially/visibly clean.

Standard infection control precautions for MRSA : 

Standard infection control precautions for MRSA Maintaining cleanliness of the patient environment (not effective in slowing outbreaks) Use of gowns and aprons (no proved value) Use of gloves (effective if changed between patients) Dispose of waste safely Maintain a safe staff to patient ratio Avoid overcrowding patients Avoid unnecessary patient transfers between wards Pre identification of carriers and previously infected patients (with total isolation, effective)

Slide 24: 

Thank you