This document discusses Methicillin-resistant Staphylococcus aureus (MRSA), including types (community-acquired and hospital-acquired), resistance mechanisms, infections it commonly causes, and treatment guidelines. MRSA is resistant to many antibiotics. Recommended treatments include vancomycin, daptomycin, linezolid, clindamycin, and combining antibiotics with rifampin. For infections like osteomyelitis and implant infections, guidelines recommend antibiotics along with surgical debridement and drainage. Duration of treatment depends on infection type and severity but is typically several weeks.

1. Dr. giridhar boyapati

2. Classification of staph. aureus
1. M.S.S.A
2. B.R.S.A
3. M.R.S.A
4. G.I.S.A

3. METHICILLIN
 Narrow spectrum beta-lactumantibiotic
 Semi synthetic penicillin
 Only i.v use
 Resistant to hydrolysis by beta lactamases
 Adverse effects :interstitial nephritis
 No longer in clinical use.

4. Methicillin resistance
mec A gene
 Acquired probably from coagulase negative
staphylococci
 S.A : penicilins > PBP-2 on cell wall
 MRSA : mec A gene encodes for PBP-2A which is
resistant to binding by penicillins

5. Methicillin resistance
 MRSA resistant to
1. penicillins
2. cephalosporins except ceftaroline
3. carbapenams
4. Flouroquilonolones
5. macrolides ( erythro, clarythro, azithro)

6. Types of MRSA
 1. COMMUNITY-ACQUIRED MRSA
 2. HOSPITAL-ACQUIRED MRSA

7. HA -MRSA
 Health care exposure required ( extensive antibiotic
therapy, admission in icu, endo-trachealtube,central
venous catheter, long duration hospital stay.)
 Presentation : bacteremia,pneumonia
 Toxin production: rare
 Highly drug resistant

8. CA -MRSA
 No health care exposure
 Presentation : asymptomatic colonization, SSTI,
bacteremia,pneumonia
 Toxin production is common
 Less drug resistant

9. .
Treatment
Protocol

10. DRUGS
 1. CLINDAMYCIN
 2. TETRACYCLINES : DOXYCYCLINE/
MINOCYCLINE
 3. TMP/SMX
 4. RIFAMPICIN
 5. LINEZOLID
 6. VANCOMYCIN
 7. Daptomycin
 8. Ceftaroline

11. Assymptomatic nasal colonization
 29% of individuals have MSSA
 1.5% have MRSA
 NO active treatment required

12. UNCOMPLICATED ABSCESS
 Incision & Drainage alone
 Antibiotic therapy not required
 Wound is left open

13. Complicated abscess
 Severe or extensive disease
 Systemic illness
 Associated comorbidities or immunosuppression
 Extremes of age
 Difficulty to drain the abscess
 Septic phlebitis
 Antibiotics for 5 to 10 days

14. Recurrent MRSA infections
 Environmental & personal hygiene
 Decolonization strategies
1. nasal decolonization: topical mupirocin
2. topical body decolonization : 4%chlorhexidine,
dilute bleech baths
3. oral antibiotis not routinely recommended.

15. Uncomplicated bacteremia
 Antibiotics for 2 weeks
 MIC testing for vancomycin and at least 1alternative
agent

16. Complicated bacteremia
 Positive echocardiogram (IE)
 Indwelling prosthetic material (valves,shunts)
 Positive blood culture even 4 days of antibiotic therapy
 Evidence of metastatic foci
 Antibiotics for 4 -6 weeks

17. Bacteriuria
 24-34% of patients with bacteremia also develop
bacteriuria.
 Bacteremia+Bacteriuria = high mortality

18. MRSA Pneumonia
 High mortality
 Treated with
linozolid
vancomycin
Daptomycin is contraindicated
Antibiotics for 7- 21 days

19. MRSA Endocarditis
Intravenous vancomycin or daptomycin (6 mg/kg iv)
for 6 weeks is recommended.
Some experts recommend higher dosages of
daptomycin (8 to 10 mg/kg iv ).
Adding gentamicin or rifampin to vancomycin is not
recommended in patients with bacteremia or native
valve infective endocarditis.

20.  Patients with infective endocarditis and a prosthetic
valve should be treated with:
Intravenous vancomycin + rifampicin+ gentamicin
for a minimum of 6 weeks.
 Early evaluation for valve replacement surgery is
recommended.

21. MRSA MENINGITIS
 Intravenous vancomycin for 2 weeks.
 Some experts recommend adding rifampin
 BRAIN ABSCESS, SUBDURAL EMPYEMA, AND
SPINAL EPIDURAL ABSCESS
 Neurosurgical evaluation for incision and drainage is
recommended
 Intravenous vancomycin for 4-6 weeks

22. MRSA infection in
Orthopaedic
surgery

23. .
Nearly half of the entire surgical site infections are
caused by staphylococci.
Of these 81% are Staph. aureus, and 63% are
resistant to methicillin.
The rate of methicillin resistance is higher in
orthopaedic units compared to other medical
specialities.
MRSA produces biofilm and becomes more
resistant to antibiotics.

25. MRSA infections
 Superficial
surface exudates
surface wound
Deep
Bacteraemia
Joint Aspirate
Bone/Soft Tissue specimens/ Surgical Implant
Deep wound/intra-operative swabs

26. Prevalence of MRSA to be
1.6% within an orthopaedic
department
0.3% within the general
hospital setting
The SENTRY study showed that although
the overall numbers of staphylococcal
infections within an orthopaedic setting
were low in comparison with those in

27. IDSA guidelines for
treatment of
MRSA infections

28. MRSA osteomylitis
 Surgical debridement and drainage of associated soft tissue
abscesses.
 Administration of antibiotic: Parenteral, oral, or initial
parenteral therapy followed by oral therapy may be used
 Antibiotics available for parenteral administration include
IV vancomycin and daptomycin 6 mg/kg/dose IV
 Oral : TMP-SMX 4 mg/kg/dose BD + rifampin 600 mg OD
linezolid 600 mg twice daily,
clindamycin 600 mg every 8 h .

29. Some experts recommend the addition of rifampin
600 mg daily or 300–450 mg twice daily to the
antibiotic chosen above.
For patients with concurrent bacteremia , rifampin
should be added after clearance of bacteremia.
 The optimal duration of therapy for MRSA
osteomyelitis is A minimum 8-week course is
recommended
 Additional 1–3 months ( for chronic infection or if
debridement is not performed) of oral rifampin-based
combination therapy with TMP-SMX,
doxycycline, minocycline, clindamycin, or a
fluoroquinolone.

30. o MRI with gadolinium is the imaging modality
of choice, particularly for detection of early
osteomyelitis and associated soft-tissue
disease .
 ESR and/or CRP level may be helpful to guide
response to therapy

31. SEPTIC ARTHRITIS
 Arthrotomy and drainage
 3-4 week course therapy recommended

32. Implant related infections
 Early-onset (less than 2months after surgery)
 Acute hematogenous prosthetic joint infections
involving a stable implant
 Short duration of symptoms (three weeks or less)
 Debridement (but device retention),
Parenteral therapy + rifampin , followed by rifampin
plus a fluoroquinolone, TMP/SMX, a tetracycline, or
clindamycin for 3 months for hips and 6 months for
knees.

33.  Late (> 2 mos postop):
 Implant is unstable,
 later onset infection or > 3wks symptoms
 Remove hardware and administer antibiotics .

34. Spinal implant related infections
 Early onset spinal implant infections (30 days or less
after surgery)
 Implants in an actively infected site,
Parenteral therapy plus rifampin followed by
prolonged oral therapy is recommended.
The optimal duration of parenteral and oral
therapy is unclear;
Oral therapy should be continued until spinal
fusion has occurred.

35.  For late-onset infections (more than 30 days after
surgery), device removal is recommended.
 Long-term oral suppressive antibiotics (e.g.,
TMP/SMX, a tetracycline, a fluoroquinolone in
conjunction with rifampin, clindamycin ) with or
without rifampin may be considered, particularly if
device removal is not possible

36. MRSA IN CHILDREN
 Vancomycin is recommended in children with acute
hematogenous MRSA osteomyelitis and septic
arthritis.
 If the patient is stable without ongoing bacteremia or
intravascular infection, clindamycin can be used.
 The duration of therapy should be individualized, but
a minimum of
3-4 weeks is for septic arthritis
4-6 weeks for osteomyelitis.
 Daptomycin and linezolid are alternative therapies