Changing Epidemiology of Staphylococcal Infections

 1st report 1940s    penicillinase-producing strains of Staphylococcus Hospital setting High risk patient (IVDU, chronic indwelling catheter)

 Upward trend in the prevalence of community-acquired MRSA strains in low risk patients  community-acquired MRSA skin and soft tissue infections increased 6.84 fold  from 24.0 cases per 100,000 people in 2000 to 164.2 cases per 100,000 people in 2005 Arch Intern Med. 2007;167:1026-33.

 similar trends of increasing prevalences of community-acquired MRSA, with the conclusions being that this is now the predominant organism in skin and soft-tissue infections N Engl J Med. 2005;352:1436-44.

 there is currently no systematic surveillance for antibiotic-resistant organisms in the community setting, the true prevalence of this organism is difficult to ascertain

Resistant Surgical Site Infections

 Fulkerson et al.

 The susceptibilities of Staphylococcus epidermidis and Staphylococcus aureus to cefazolin were only 44% and 74%  These Staphylococcus epidermidis and Staphylococcus aureus infections were 100% sensitive to vancomycin J Bone Joint Surg Am. 2006;88:1231-7.

 Phillips et al.

   1987~2001, 5947 hip replacements & 4788 knee replacements Infection rate 0.57% & 0.86 % Prophylaxis : cefuroxime    (resistant rate 29%) MRSA (3/3) Pseudomonas aeruginosa (3/3) coagulase-negative Staphylococcus (11/27) J Bone Joint Surg Br. 2006;88:943-8.

  The recommended prophylactic antibiotic agents, cefazolin and cefuroxime, lacked activity against MRSA and MRSE. The prevalences of these organisms as causes of infections are increasing according to the antibiogram data of numerous hospitals

Prophylactic Antibiotics in Institutions with High Bacterial Resistance

  Use Vancomycin as prophylactic A/B (alone or combination)  controversial Recommendations for the use of intravenous antibiotic prophylaxis in primary total joint arthroplasty. AAOS.2004

  Clindamycin or vancomycin may be used for patients with a confirmed b-lactam allergy Vancomycin may be used in patients with known colonization with MRSA or in facilities with recent MRSA outbreaks

 The use of prophylactic antibiotics in orthopaedic medicine and the emergence of vancomycin-resistant bacteria. AAOS. 2002  Vancomycin may be appropriate as a prophylactic antimicrobial for patients undergoing joint replacement at institutions that have identified a significant prevalence (e.g., >10-20 percent ) of MRSA and MRSE among orthopaedic patients

 The Hospital Infection Control Practices Advisory Committee guideline  a high frequency of MRSA infection at an institution should influence the use of vancomycin for prophylaxis

Vancomycin

   A large tricyclic glycopeptide molecule Bactericidal action is a result of the inhibition of bacterial cell wall synthesis Active against most gram-positive organisms  Staphylococcus aureus, Staphylococcus epidermidis, streptococci, enterococci, and Clostridium

  Reaches high concentrations in bone, synovial tissue, and muscle within minutes Adverse reactions     Red man syndrome (5~13%)  a pruritic, erythematous rash   occasionally accompanied by hypotension its rapid infusion and histamine release Nephrotoxicity, ototoxicity < 1% Reversible neutropenia Drug fever Daptomycin should be considered as an alternative

  For prophylaxis, its infusion should begin one to two hours before initiation of the operation within one hour for cefazolin  repeat administration is recommended in six to twelve hours Dose: 10~15 mg/kg

 Cardiac surgery     Prophylaxis with Cefazolin vs. Vancomycin Infection rate: no difference Difference in the types of surgical site infection The choice of prophylaxis changed the flora of infections but not the rate of infections Clin Infect Dis. 2004;38:1706-15.

  Ritter et al.

  Orthopedics. 1989;12:1333-6.

A single dose of vancomycin and gentamicin preoperatively  safe and effective no early infections in this case series Savarese et al.

 Chir Organi Mov. 1999;84:247-51.

1 g of vancomycin given one hour before and six hours after the operation

Vancomycin resistance

   The first staphylococci with reduced susceptibility to vancomycin  Vancomycin-intermediate Staphylococcus aureus Morb Mortal Wkly Rep. 1997;46:624-6.

Vancomycin resistant Staphylococcus aureus  Occur infrequently Morb Mortal Wkly Rep. 2002;51:565-7.

Newer A/B  linezolid, quinupristin/dalfopristin, daptomycin, and tigecycline

Role of Screening for Methicillin Resistant Staphylococcus aureus

  Patients may be screened to determine whether they are colonized with drug resistant bacteria Robicsek et al.

Ann Intern Med. 2008;148:409-18  reported a reduction by more than half in health care-associated MRSA

  Perl et al.   N Engl J Med. 2002;346:1871-7.

No significant reduction of surgical site infections by Staphylococcus aureus nasal mupirocin did reduce the rate of infections among patients who were previously Staphylococcus aureus carriers Kalmeijer et al.  Clin Infect Dis. 2002;35:353-8.

Five (1.6%) of 315 cases in the mupirocin group compared with eight (2.7%) of 299 in the placebo group, which was not a significant difference

 on preoperative nasal decolonization in patients undergoing orthopaedic joint replacement procedures Clin Orthop Relat Res. 2008;466:1349-55.

Clin Orthop Relat Res. 2008;466:1343-8

Local Antibiotic Prophylaxis

  Aminioglycosides  cause bacterial cell death by an intracellular mechanism, binding to a 30S subunit of the ribosome and thereby inhibiting protein synthesis Buchholz et al.

 addition of aminoglycoside antibiotics to Palacos bone cement in a large series of exchange arthroplasties Bone Joint Surg Br. 1981;63:342-53.

  Josefsson et al.

  a series of 1688 consecutive total hip arthroplasties followed for ten years it might be beneficial to use parenteral antibiotics and antibiotic bone cement concurrently FDA   Clin Orthop Relat Res. 1981;159:194-200.

Clin Orthop Relat Res. 1990;253:173-8.

premixed antibiotic bone cement for prophylaxis in a second-stage re-implantation but not as prophylaxis in routine primary arthroplasties

Overview

   Low prevalence of surgical site infections associated with hip and knee arthroplasty  difficult to study Reduction in infections  Measures related to operative technique  Operating-room environment For the last three decades, the cephalosporins (cefazolin and cefuroxime) have been the preferred antimicrobials

 Increasing rates of community-acquired infections  cefazolin or cefuroxime alone might not be the appropriate prophylaxis in all surgical settings    Staphylococcus aureus resistance to cefazolin is 50% Staphylococcus epidermidis resistance to cefazolin is 70% Vancomycin along with Cefazolin

Thanks for your attention