Download Objectives for Staph aureus bacteremia discussion

Resident Version
Staphylococcus aureus bacteremia module
Created by Dr. Wendy Gerstein
updated 10/2010
Objectives:
1) Recognize two clinical differences and implications between spontaneous and
catheter related S. aureus bacteremia.
2) List the criteria for type and duration of therapy for S. aureus bacteremia.
3) Recognize three common complications associated with S. aureus bacteremia.
References:
1) Mermel LA, Farr BM, Sheretz RJ et al. Guidelines for the Management of
Intravascular Catheter-Related Infections. CID 2001:32 (1 May) 1249-1272.
2) Rosen AB, Fowler VG Jr, Corey GR et al. Cost-effectiveness of transesophageal
echocardiography to determine the duration of therapy for intravascular catheterassociated Staphylococcus aureus bacteremia. Ann Intern Med. 1999; 130:810-20
Case:
HPI: Mr. T is a 56 yo male with a history of severe COPD (on home O2 and chronic
steroids), DM, HTN, DVT/PE, who come to the ED complaining of dysuria, hematuria,
left sided back pain, suprapubic abdominal pain, and fever/chills for the past 2 days. He
was seen in ED the day prior to admission, given IV ciprofloxacin for presumed
UTI/pyelonephritis, and sent home with oral ciprofloxacin. He took one dose but was
unable to tolerate it because of emesis. He has had emesis x 7 the day of admission. Mr.
T has just finished a steroid taper 5 days ago and feels like he is more SOB and has more
productive cough with yellowish sputum.
PMH
Severe COPD--(FEV1 1.36, 35% predicted, on home O2, on chronic steroids)
HTN
DM--hga1c 5.5
GERD
PE 5 years ago and DVT 12 years ago--on chronic coumadin therapy
BPH
GI bleed 2 years ago: friable nodule found at GE junction by EGD, negative biopsy.
MRSA UTI 10 months prior
SH
Lives in Portales with his wife. Denies tobacco or drug use; h/o heavy ETOH abuse and
quit 7 years ago. Used to drink a 5th of vodka every day for 7 years.
FMH
Mother: died age 65 lung ca
Dad: died age 65 of CAD
CHF in siblings
ALLERGIES
NKDA
OUTPATIENT MEDICATIONS
Inhaler for COPD
Ciprofloxacin 500 mg po bid
Citalopram 40 mg 1 po q day
Insulin NPH 5 units q bedtime, insulin ss before meals.
Irbesartan 150 mg 1 po q day
Lovastatin 10 mg 1 po q day
Oxycodone 5 mg 1 po tid for pain
Pantoprazole 40 mg 1 po bid
Prednisone 10 mg 1 po q day
Spironalactone 25 mg 1 po bid
Warfarin
PE:
BP 104/54, P 108, RR 14, T 102.8, O2 94% 3L NC
General: AAO x 3, NAD
HEENT: PERRLA, EOMI, pharynx w/ post nasal drainage, no LAD, neck supple,
thyroid normal.
Lungs: scattered crackles, prolonged expiratory phase, and few scattered wheezes.
CV: RRR no m/r/g, no JVD, no s3/4, equal dp/radial pulses
Abd: soft, non-distended, mild suprapubic tenderness, +bs
Back: L CVA tenderness
Ext: No C/C/E
Neuro: CN 2-12 grossly intact, motor/strength in 4 extremities grossly intact
LABS
WBC/H/H/Plt:18.8/16/48/96-->plt 145 in 2/06
Na/K/Cl/CO2/BUN/Cr/Glc:130/3.8/98/25/12/1.1/139
Ca/Mg:8.3/1.7
TP/Alb/AST/ALT/AP/TB:6.1/3.1/29/47/61/0.9
CXR: poor quality portable, hypoventilation, B basilar atelectasis
blood/urine cultures pending
UA (initial ED visit): nitrite +, mod LCE, 102 wbc, 18 rbc
UA day of admission: nitrite -, trace LCE, 25 WBC, 150 ketones
What is your initial impression or diagnosis based on presentation and above data?
Hospital Course:
Patient admitted with diagnosis of pyelonephritis, and inability to tolerate PO
antibiotics. Patient was started on IV ciprofloxacin, and also treated for a COPD
exacerbation with steroids and nebulizers. By hospital day 2, patient was improved, and
urine and blood cultures were still negative. Approximately 5 hours after his discharge,
the medical team was notified that 1/4 blood cultures were growing gram positive cocci
in clusters. Medical team was concerned due to h/o MRSA UTI, but was unable to
contact patient at home. The next morning 4/4 blood cultures were growing S. aureus
with sensitivities pending. Team reached patient and wife as they were traveling home.
Wife stated that her husband was still doing OK, but he felt a little weaker than yesterday,
and patient returned to be readmitted.
What is the next step in managing this patient?
What is the most likely source of the MRSA bacteremia?
What further evaluation is warranted?
Outline for discussion
Community-acquired (spontaneous) S. aureus bacteremia:
(Of note, there is a separate module for endocarditis)
A) Epidemiology
 Leading cause of community-acquired bacteremia.
 It is a marker for complicated disease: >40% of patients have metastatic
disease and in one study 60% had endocarditis.
 It has significant mortality associated with it: 20-40% depending upon
underlying comorbities.
B) Risk factors:
 IVDU
 Indwelling foreign body/prosthesis
 Underlying medical conditions (HIV, hemodialysis patients, diabetes,
malignancy, nasal carriers).
C) Management/workup:
 Look for deep focus of infection (osteomyelitis, abscess, endocarditis, prosthetic
infection), and drain or debride if possible.
 Repeat blood cultures until documented clearance of bacteremia.
 Remove any associated hardware or prosthesis if feasible.
 All patients with S. aureus bacteremia should have a transthoracic
echocardiogram (TTE).
Transesophageal echocardiogram (TEE) to rule out vegetation has been proven to
be cost effective; perform if feasible unless 6 weeks of therapy is already going to
be given for other known deep focus of infection. If signs of endocarditis are
present, TEE helps evaluate for complications (embolic phenomenon, chf, size of
vegetation).
D) Treatment:
 Methicillin sensitive S. aureus (MSSA)
o nafcillin 2 grams iv q 4 hours is drug of choice.
o Cefazolin 2 grams iv q 8 hours if patient with h/o type 4 beta-lactam
allergy.
o Vancomycin 30mg/kg per day divided over 8-12 hour dosing if patient
with type 1 beta-lactam allergy (follow troughs aiming for level of 1520).
o Linezolid is 3rd line therapy if patient refuses IV (600mg po bid). You can
also use oral dicloxacillin if patient leaves AMA (linezolid needs
monitoring).
 Methicillin resistant S. aureus (MRSA)
o Vancomycin 30mg/kg per day divided over 8-12 hour dosing, follow
troughs aiming for level of 15-20.
o Daptomycin 6mg/kg q 24 hours is an alternative treatment for MRSA,
need to monitor for elevated CPK.
E) Duration of therapy:
 Duration (minimum is 14 days) depends on presence or absence of the following:
o Removable focus
o Response to initial therapy (blood culture results at three days)
o Presence of prosthesis, deep focus, or endocarditis.
F) Complications of bacteremia:
o Relapse rate of bacteremia is 9.4% with endocarditis, or if vancomycin used.
o Septic thrombosis, endocarditis, purulent pericarditis (seen in HIV patients), deep
abscesses, prosthetic infection, vertebral osteomyelitis, septic arthritis (RA),
septic pulmonary emboli, bacteriuria (look for source of S. aureus bacteriuria
such as endocarditis, renal abscess, prostatitis).
G) Catheter-related S. aureus bacteremia:
o Diagnosis: catheter tip culture positive (quantitative or semi-quantitative) and
blood culture positive for same organism, or peripheral blood culture and blood
culture from catheter positive with same organism. Clinical findings tend to be
unreliable.
o Mortality rate for catheter associated S. aureus bacteremia is lower than for
community-acquired: 8.2%. Much fewer develop endocarditis compared to
community-acquired S. aureus bacteremia
o Central venous catheters accounts for >90% of catheter infections (less common
with tunneled/implantable catheters).
o Treatment:
o If CVC, remove and treat with antibiotic (vancomycin or nafcillin
depending on organism and allergies) for 14 days minimum (assuming
TTE/TEE negative for vegetation, and no clinical evidence of deep
infection or embolic phenomenon). If unable to get TEE, base duration on
clinical picture and TTE results.
o If TEE positive, treat as endocarditis with 6 weeks of appropriate therapy
o Tunneled/implantable catheter infection: if complicated, remove catheter.
If non-complicated, can attempt salvage therapy (<50% success) with
antibiotic lock therapy for 2 weeks in addition to systemic antibiotics,
although guidelines always recommend removing due to high failure rate.
o Complications are similar to community-acquired S. aureus bacteremia:
endocarditis, osteomyelitis, septic thrombosis, deep tissue space infection
(liver, kidney, spleen), epidural abscess.
Review questions
1) 38 yo male with past medical history significant for end stage renal disease, on
dialysis, who had a permacatheter placed 2 weeks prior to admission due to failure of his
fistula (it clotted off). Two days prior to admission patient noted fevers/chills/diarrhea
and pus coming out of permacath site. 2 sets of blood cultures are drawn, patient is
dialyzed, one dose of vancomycin is given, and permacatheter is removed.
The patient improves, but blood cultures from admission grow Staphylococcus aureus
that is methicillin resistant. Patient has a new permacatheter placed, and repeat blood
cultures are negative. Physical exam is negative for any signs of endocarditis, patient is
afebrile with normal exam, normal wbc, old permacath site has healed well, and he is
anxious to go home.
Which of the following is the most appropriate management of this patient?
A. With negative blood cultures and a new permacatheter placed, patient does not need
any more studies or therapy and is safe to discharge home.
B. Patient is safe to go home with no further diagnostic studies, but will need the IV
vancomycin for 2 weeks with dialysis.
C. Obtain a transthoracic echocardiogram – if negative, patient does not need any more
therapy.
D. Obtain a transesophageal echocardiogram. If negative for endocarditis, continue the
IV vancomycin for 2 weeks.
E. Obtain a transesophageal echocardiogram. If negative for endocarditis can discontinue
antibiotics.
2) An IVDU presents with right-sided endocarditis and is growing methicillin sensitive S.
aureus in their blood cultures.
Standard of care treatment is:
A) 4 weeks of IV vancomycin and low-dose (q 8 hour) gentamicin
B) 2 weeks of IV vancomycin
C) 4 weeks of IV nafcillin
D) 2 weeks of IV nafcillin plus low-dose (q 8 hour) gentamicin
E) 4 weeks of oral ciprofloxacin plus rifampin
3) A 45 yo male had a right knee prosthesis placed 6 weeks ago, and now presents with
increasing knee pain for two weeks, swelling, purulent drainage from wound,
fevers/rigors, and malaise. Physical exam is notable for temperature of 39 C, bp 90/50, p
110, RR 16. R knee wound has dehisced with greenish discharge, and surrounding edema
and erythema is present, with pain with palpation or any movement. Patient was started
empirically on IV vancomycin at time of admission. Blood cultures drawn prior to
antibiotics are now growing methicillin-sensitive S. aureus. The next most appropriate
management is:
A) Continue IV vancomycin, contact orthopedics for removal of hardware, and treat for 6
week with vancomycin.
B) Switch to IV nafcillin, contact orthopedics for removal of hardware, and treat for 6
weeks with nafcillin.
C) Switch to IV nafcillin, contact orthopedics for irrigation and debridement of knee,
continue antibiotics for 6-8 weeks.
D) Switch to IV nafcillin for duration of hospitalization, contact orthopedics for irrigation
and debridement of knee, and send home on oral suppressive therapy with ciprofloxacin
and rifampin indefinitely.
E) Continue IV vancomycin, add rifampin, contact orthopedics for irrigation and
debridement of knee, and treat for 6-8 weeks with vancomycin and rifampin.
Post Module Evaluation
Please place completed evaluation in an interdepartmental mail envelope and address to
Dr. Wendy Gerstein, Department of Medicine, VAMC (111).
1) Topic of module:__________________________
2) On a scale of 1-5, how effective was this module for learning this topic? _________
(1= not effective at all, 5 = extremely effective)
3) Were there any obvious errors, confusing data, or omissions? Please list/comment
below:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
4) Was the attending involved in the teaching of this module? Yes/no (please circle).
5) Please provide any further comments/feedback about this module, or the inpatient
curriculum in general:
6) Please circle one:
Attending
Resident (R2/R3)
Intern
Medical student