03. Staphylococcal bacteremia by ucfm2005

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									Staphylococcal bacteremia




     Shannon Galvin, M.D.
     August 2006
        Staph bacteremia
Overview
Clinical syndromes
How to treat
Complications
GPC in blood
Other positive cultures
             Bacteremia
Nosocomial
   Most common pathogen—Staph epi
   2nd Staph aureus—20% of nosocomial
   bacteremias
   Risk factors—IV catheters, severe pneumonia,
   surgical wound, foreign body, dialysis
Community acquired
   More likely to have IVDU, epidural abscess
   Australia 2005 49% of staph bacteremias
   community onset, 12% of these MRSA
Wisplinghoff et al. Clin Infect Dis. 2004 Aug; 39(3)
           Coag neg Staph
Consider as a pathogen when…
 2 or more positive cultures from different
 sites
 Clinical findings of infection especially in
 immunocompromised patient
 Similar genotype from different time points
 Isolated from a sterile site—joint, CSF
 especially if prosthetic device present
 (shunt, artificial joint)
     Staph aureus bacteremia
Serious life threatening infection
30% mortality
20% severe metastatic complications

Any positive culture for Staph aureus from a
 sterile site must be treated
5147
Staphylococcus aureus
                 MRSA
UNC antibiogram 2004
Staph aureus-57% oxacillin susceptible



Nationwide approx 53% ICU, 46% inpatient
 31% outpatient isolates were MRSA
                     MRSA
Is MRSA more virulent than MSSA?
Unclear, but patients with MRSA bacteremia tend
   to have higher morbidity and mortality
   Efficacy of therapy-vanc inferior to
   nafcillin/oxacillin
       MSSA relapse 19% vanc vs 0% nafcillin Chang
     Medicine 2003
      MRSA independent poor prognostic factor in
      Staph endocarditis
  Differences in host populations
            Community MRSA
   Defined as seen in patients with no health care contact
   in past year and positive cultures within 48 hours of
   admission or in outpatient setting
   Seems especially prevalent in military personnel
   Presents as soft tissue abscess- ―bug bite‖ that can be
   progressive and associated with bacteremia
   Always check sensitivities
   Initially can use trimethoprim-sulfamethoxazole or
   Clindamycin- however resistance to this is inducible,
   make sure a D-test is performed
Vancomycin for serious infections
Linezolid also an option
7824
D- test Blunting of the clindamycin susceptibility zone adjacent to the erythromycin zone
        Clinical syndromes
Catheter associated infections
Endocarditis versus Bacteremia
Suppurative complications
– Vertebral osteomyelitis and discitis
– Septic arthritis
– Splenic abscess
– Meningitis
– Deep tissue abscess
           Complications
Patients at highest risk for complications
– Absence of identifiable focus
– > 3days of positive cultures (OR 5.58)



Clinical examination underestimates the
 frequency of complications
           Complications
Endocarditis
Vertebral osteomyelitis/discitis
Septic arthritis
Splenic abscess
Mycotic aneurysms
Meningitis
Tissue abscess
 Risk of endocarditis with Staph
           bacteremia

Series of patients with S. aureus
bacteremia
– 25% had endocarditis by TEE
– 7% by TTE
Definite infective endocarditis
  Pathological criteria
    Microorganisms demonstrated by culture or histological examination of a
vegetation, a vegetation that has embolized, or an intracardiac abscess specimen; or
    Pathological lesions; vegetation or intracardiac abscess confirmed by histological
examination showing active endocarditis
  Clinical criteria
     2 major criteria; or
     1 major criterion and 3 minor criteria; or
     5 minor criteria
  Possible IE
     1 major criterion and 1 minor criterion; or
     3 minor criteria
  Rejected
     Firm alternative diagnosis explaining evidence of IE; or
     Resolution of IE syndrome with antibiotic therapy for <4 days; or
    No pathological evidence of IE at surgery or autopsy, with antibiotic therapy for <4
days; or
     Does not meet criteria for possible IE as above
Major criteria
   Blood culture positive for IE
     Typical microorganisms consistent with IE from 2 separate blood cultures: Viridans
streptococci, Streptococcus bovis, HACEK group, Staphylococcus aureus; or
community-acquired enterococci in the absence of a primary focus; or
     Microorganisms consistent with IE from persistently positive blood cultures defined
as follows: At least 2 positive cultures of blood samples drawn >12 h apart; or all of 3 or
a majority of 4 separate cultures of blood (with first and last sample drawn at least 1 h
apart)
     Single positive blood culture for Coxiella burnetii or anti–phase 1 IgG
antibody titer >1:800
  Evidence of endocardial involvement
      Echocardiogram positive for IE (TEE recommended for patients with prosthetic
valves, rated at least "possible IE" by clinical criteria, or complicated IE
[paravalvular abscess]; TTE as first test in other patients) defined as follows:
oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant
jets, or on implanted material in the absence of an alternative anatomic explanation; or
abscess; or new partial dehiscence of prosthetic valve; new valvular regurgitation
(worsening or changing or preexisting murmur not sufficient)
Minor criteria
  Predisposition, predisposing heart condition, or IDU
  Fever, temperature >38°C
  Vascular phenomena, major arterial emboli, septic pulmonary infarcts, mycotic
aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway’s lesions
  Immunologic phenomena: glomerulonephritis, Osler’s nodes, Roth’s spots, and
rheumatoid factor
  Microbiological evidence: positive blood culture but does not meet a major criterion as
noted above* or serological evidence of active infection with organism consistent with IE
  Echocardiographic minor criteria eliminated
                     TTE vs TEE
Catheter associated Staph bacteremia-
estimated probability of endocarditis 3-4%
here TTE is cost effective
Unexplained bacteremia-estimated risk of
endocarditis 4-50% but for Staph probably
exceeds 25% here TEE is cost effective
Heidenreich PA et al. Echocardiography in patients with suspected
endocarditis: a cost effective analyis
  Chang FY, MacDonald BB, Peacock JE Jr, Musher DM, Triplett P,
           Mylotte JM, O'Donnell A, Wagener MM, Yu VL.
A prospective multicenter study of Staphylococcus aureus bacteremia:
incidence of endocarditis, risk factors for mortality, and clinical impact
                      of methicillin resistance.

           Medicine (Baltimore). 2003 Sep;82(5):322-32
 Observational study of 505 pts with Staph bacteremia
 13% had found to have endocarditis
  – 21% of community acquired bacteremias, 5% hospital acquired, 12% of
    dialysis acquired
  MRSA pts had more persistent bactermia, MRSA an independent
    predictor of death from endocarditis
  Positive blood cultures at day 3, valvular heart disease, IVDU,
    community acquired source, or unknown source risks for having
    endocarditis
  31% 30 day mortality for endocarditis, 21% others
 Van Hal SJ, Mathur G, Kelly J, Aronis C, Cranney GB, Jones PD. The role of
transthoracic echocardiography in excluding left sided infective endocarditis in

    Staphylococcus aureus bacteraemia. J Infect. 2005 Oct;51(3):218-21.

      Retrospective study of 125/800 pts at a single
      center who had both TTE and TEE.
      Negative likelihood ratio 0.33 for endocarditis
      with normal TTE

      Endocarditis by TEE was found in less than 2%
      of patients without embolic phenomena with
      normal (no valvular lesions, and no or trivial
      regurgitation) echo
Management of catheter-related Staphylococcus aureus bacteremia:
            when may sonographic study be unnecessary?
Pigrau C, Rodriguez D, Planes AM, Almirante B, Larrosa N, Ribera E,
      Gavalda J, Pahissa A. Eur J Clin Microbiol Infect Dis. 2003
                            Dec;22(12):713-9.
  213 episodes of bacteremia were registered and 167 (78.4%) were
  nosocomial. Among these, 87 (52.1%) were catheter-related
  Staphylococcus aureus bacteremia and 20 were primary nosocomial
  bacteremia. Endocarditis was diagnosed during the acute episode in
  7/107 of these patients (2 by persistent fever after catheter removal
  and 5 by metastatic foci; 3 of them also had cardiac risk factors) and
  confirmed with transesophageal echocardiography. Among the
  84/87 catheter-related Staphylococcus aureus bacteremia and 16/20
  primary nosocomial bacteremia patients who did not develop
  endocarditis, 31 patients died during the acute episode (16 due to
  sepsis despite initiation of antibiotic treatment and 15 due to the
  underlying disease) and five had osteoarticular foci. 64 episodes
  were considered to be uncomplicated bacteremia (no cardiac risk
  factors, persistent fever, metastatic foci, or clinical signs of
  endocarditis) and were treated with 10-14 days of high-dose
  antistaphylococcal antibiotics. Echocardiography was not mandatory
  in these patients. Of the 64 uncomplicated episodes, 62 were
  followed for at least 3 months and none relapsed or developed
  endocarditis
           Complications
Endocarditis
Vertebral osteomyelitis/discitis
Septic arthritis
Splenic abscess
Mycotic aneurysms
Meningitis
Tissue abscess
       Principles of treatment
Remove focus-<18% treatment success if focus
  remains
Drain fluid collections
Replace/remove prosthetic device if possible
High risk of endocarditis-need echo
  TTE for line infections with no embolic
  stigmata???, TEE for all others vs TEE for all
Vertebral osteo/deep soft tissue abscess often
  overlooked-may require imaging
                 Treatment
  Simple bacteremia—focus removed, neg echo,
  normal heart valves, repeat cultures at 3 days
  negative—14 days
  Complicated-positive blood cultures at 3 days,
  continued fevers-consider imaging for osteo/soft
  tissue focus—treat for 3-4 weeks
Endocarditis-treat for 4-6 weeks
Osteo/abscess-drain focus treat for 4-8 weeks
                Daptomycin
Daptomycin 6mg/kg daily n=124 vs antiStaph PCN/Vanc
plus gent (n=122)
At 42 days ―successful outcome‖ 44% dapto vs 41%
showing noninferiority
Failure to reach successful outcome included death,
clinical or microbiologic failure, or discontinuation of
study drug due to adverse event or failure
Higher rate of microbiologic failure in daptomycin
More adverse renal events in standard therapy
Reduced susceptibility noted in daptomycin and vanc not
in oxacillin treated subjects
CK elevations in 6% of daptomycin treated subjects
                   Shorr AF, Kunkel MJ, Kollef M.
Linezolid versus vancomycin for Staphylococcus aureus bacteraemia:
               pooled analysis of randomized studies.

         J Antimicrob Chemother. 2005 Nov;56(5):923-9.
 Meta-analysis
 Clinical cure 14 (56%) of 25 linezolid
 recipients and 13 (46%) of 28 vancomycin
 recipients (OR, 1.47; 95% CI, 0.50-4.34).
 Microbiological success occurred in 41
 (69%) of 59 linezolid recipients and 41
 (73%) of 56 vancomycin recipients (OR,
 0.83; 95% CI, 0.37-1.87
 Numerous case reports of Staph aureus
 developing linezolid resistance on therapy
          Always treat
Any Staph aureus—blood, CSF, urine,
most body fluids
Any fungus in blood, CSF
GNR in blood

								
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