Publication/Presentation Date



Hospital-wide Impact of Mandatory Infectious Disease Consultation on Staphylococcus aureus Septicemia

Amanda Guth1

Amy Slenker MD1,2

1Department of Infectious Diseases, Lehigh Valley Health Network

2Research Scholar Program Mentor


Staphylococcus aureus bacteremia (SAB) is associated with considerable morbidity mortality1. Mandatory Infectious Diseases (ID) consultation for SAB was introduced to the Lehigh Valley Health Network in order to improve the care of SAB patients at both the Cedar Crest and Muhlenberg campuses. This study sought to determine if mandatory ID consultation improves adherence to published guidelines on quality-of-care indicators and improves outcomes of patients with SAB. A retrospective study was conducted comparing 179 SAB patients from the pre-intervention period (January 2013 through December 2013), to 197 SAB patients from the intervention period (May 2014 through May 2015). Comparison of the pre-intervention and intervention group revealed that the incidence of ID consultation was similar between the two groups (98% vs 98%, p=NS); however, there was a significant improvement in appropriate duration of treatment (72% vs 91%, p=0.009), and appropriate antibiotic deescalation in patients with methicillin-sensitive SAB (37% vs. 53%, p=0.012) between the pre-intervention and intervention groups. The implementation of mandatory ID consultation resulted in improvement in the quality of care for SAB patients. Though the sample size was small and the duration of this study short, this quality improvement study is useful in examining the factors that lead to better patient care and aid in the advancement of standard-of-care protocols for SAB patients hospital-wide.


Staphylococcus aureus bacteremia (SAB) is a major human pathogen that causes a wide-range of clinical infections.6 It is a leading cause of bacteremia and infective endocarditis, as well osteoarticular, skin and soft tissue, and device-related infections.6 It is also one of the main contributors to both hospital and community-onset bloodstream infections worldwide.5 SAB continues to grow in number and complexity as a consequence of advances in patient care and the pathogen’s ability to adapt to a changing environment.7 It is associated with considerable morbidity and 10%-30% mortality1.

ID consultations for SAB have been shown to improve outcomes, including: increased cure rates2, decreased mortality3, and improved compliance with treatment standards-of-care4. ID consultation has also been shown to improve adherence to six quality-of-care indicators (QCI): performance of follow-up blood cultures, performance of echocardiography, appropriate antibiotic choice, particularly de-escalation to a β-lactam in methicillin-sensitive SAB, length of therapy, early source control (removal of infected intravenous catheters or drainage of abscess), and adjustment of vancomycin dosing5.

Lehigh Valley Health Network instituted mandatory ID consultations for patients with SAB on May 12, 2014. The purpose of this quality improvement project was to evaluate the impact of ID consultation on the management and outcome in patients with SAB.


276 patients from Lehigh Valley Cedar Crest (CC) and Muhlenberg (MHC) campuses had positive S. aureus blood cultures and met the predefined study inclusion criteria. Patients were identified from ICD-9 codes indicating “methicillin-sensitive S. aureus (MSSA) septicemia” or “methicillin-resistant S.aureus (MRSA) septicemia.” In addition, the microbiology laboratory provided a list of all positive S. aureus blood cultures during the study period to cross-reference so that every instance of SAB was reviewed for possible inclusion.

The following patients were excluded from analysis: (1) less than eighteen years of age, (2) had polymicrobial bacteremia, (3) if they refused treatment, or (4) experienced death, transfer, or initiation of hospice care within 24 hours of positive S. aureus blood cultures.

179 patients were identified from January 1st 2013 to December 31st 2013, prior to the institution of mandatory ID SAB consultation, and 197 patients were identified from May 12, 2014 to May 11, 2015, the intervention period. During the intervention period, all positive blood culture reports for MSSA or MRSA were entered into the microbiology system with the notation “An Infectious Disease consult is indicated for patients identified with Staphylococcus aureus bacteremia.” Positive S. aureus blood cultures were faxed to the ID office for notification. If no consult request was received from the patient’s primary physician within 24 hours of the positive blood culture, the ID specialist contacted the attending of record directly to request involvement in the patient’s care.

The cohorts were evaluated using two databases that were constructed using Microsoft Access, one that captured pre-intervention patients and the other that captured intervention patients.

The patients’ medical records were reviewed for demographic data, features of S. aureus bacteremia, details regarding treatment, and outcomes. These categories were chosen and defined by a cohort of previous studies that have found these features to be either attributing factors to the development of S. aureus bacteremia or good evaluators of quality-of-care.1, 2, 3, 4, 5

All variables were then compared an analyzed using the Mann-Whitney or t test test on Minitab 17.


The characteristics of patients with Staphylococcus aureus bacteremia were very similar between the two groups. There was a notable exception of female-predominance in the pre-intervention group (46% vs 33%, p=0.007), and an increased the number of community-acquired infections in the intervention period (62% vs 45%, 0.003) (Table 1).

Most of the particular features of S. aureus infection in the pre-intervention and intervention patients were similar (Table 2). However, there were significantly more endocarditis patients in the intervention period than there were during the pre-intervention period (28% vs 21%, p=0.009). Data from prior studies suggest that infective endocarditis is associated with community-acquired infections.8

ID consultation in the period prior to the introduction of mandatory SAB consultations was quite robust (98%) with little room for improvement. Despite this, during the intervention period, there was a significant improvement in the duration of appropriate antibiotic duration (72% vs. 91%, p=0.009). In addition, there was a significant improvement in appropriate deescalation to a β–lactam antibiotic in methicillin-sensitive SAB (37 vs. 53%, p=0.012) as well as improvement in the time to de-escalation in hours (64 vs 41, p=0.0001) . Performance of echocardiography, another quality-of-care indicator showed a trend toward improved adherence (83% vs. 92%, p=0.126), with a significant increase in the number of transesophageal echocardiograms performed (37% vs. 56%, p=0.0026, Table 3).

Interestingly, there was a significant difference between the amount of patients receiving follow up blood cultures 48-96 hours after a positive blood culture during the pre-intervention period versus the intervention period (89% vs 77%, p=0.042, Table 3). This needs to be looked at more closely; as often, repeat blood cultures are taken within a more narrow time frame (24-48 hours) with improvements in early laboratory identification of the infecting organism. The quality-of-care indicator from the literature cites a specific time frame, likely as a refection of older techniques in which the Staphylococcus aureus organism is not identified as readily. A future evaluation of the data will look for if repeat blood cultures were ever taken without the noted time constraint of 48-96 hours later.

There was no significant difference in outcome measures between the two groups for hospital length of stay, attributable mortality (48% vs 66%, p=0.149) and 14-day and 30-day mortality. There was a significant difference in all-cause mortality between the two cohorts (32% vs 19%, p=0.0281) (Table 4).


The incidence of ID consultation did not change during the pre-intervention and intervention periods. Despite this, the program introducing mandatory ID consults did aid in improving adherence to quality-of-care indicators, particularly appropriate duration of antibiotics and appropriate and timely de-escalation of antibiotics in patients with methicillin-sensitive SAB. Even with the mandatory ID consultation protocol in place, four patients never received an ID consult (Table 3). This is likely secondary to human error as the microbiology laboratory technicians are responsible for faxing positive SAB blood cultures to the ID office for review. In the future, an automatic facsimile will be sent whenever SAB is identified in order to improve the rate of ID consultation for SAB to 100%.

There was a significant difference in the number of female patients between the two cohorts. However, there is no literature to support an association of gender with Staphylococcus aureus bacteremia. This is most likely a confounding result from the study’s small data size, but it should be examined further in future analyses.

All-cause mortality was significantly improved in the intervention group, however, that is most likely a reflection of the short duration of follow-up with patients from the intervention period. The intervention data collection ended May 11th, 2015 and thus 2 months have lapsed since this period versus 19 months for the pre-intervention group.

This study was a retrospective chart review to aid in the quality improvement of patients with SAB. It does have limitations that should be taken into account. This was a short duration, small, retrospective cohort study. However, the introduction of a mandatory program is helpful to a hospital as large as Lehigh Valley Health Network as it aids to bring a more standardized method of care to patients on a much grander scale.

In conclusion, this study’s results continues to add to the evidence that shows mandatory ID consultation improves clinical management, increases adherence to quality-of-care indicators, and potentially improves outcomes with patients who have Staphylococcus aureus bacteremia (SAB). A future challenge for the ID division is to continue improving this protocol and to ensure that it is effective in enhancing patient care.


  1. Chang, Feng-Yee, MacDonald BB, Peacock JE Jr, et al. A prospective multicenter study of Staphylococcus aureus bacteremia: incidence of endocarditis, risk factors for mortality, and clinical impact of methicillin resistance. Medicine. 82(5):322-32, 2003 Sep.
  2. Outcome of Staphylococcus aureus bacteremia according to compliance with recommendations of Infectious diseases specialists: experience with 244 patients. Clin Infect Dis 1998; 27:478.
  3. Infectious diseases consultation lowers mortality from Staphylococcus aureus bacteremia. Medicine (Baltimore) 2009; 88:263.
  4. Impact of routine infectious diseases service consultation on the evaluation, management, and outcomes of Staphylococcus aureus bacteremia. Clin Infect Dis 2008; 46:1000
  5. Lopez-Cortes LE, Del Toro MD, Galvez-Acebal J, et al. Impact of an evidence-based bundle intervention in the quality-of-care management and outcome of Staphylococcus aureus bacteremia. Clin Infect Dis. 2013; 57:1225.
  6. Tong SYC, Davis JS, Eichenberger E, Holland TL, Fowler VG, Jr. 27 May 2015. Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management. Clin Microbiol Rev 2015; 10.1128/CMR.00134-14.
  7. Boucher HW, Corey RG. Epidemiology of methicillin-resistant Staphylococcus aureus. Clin Infect Dis 2008; 46:5
  8. Kim SH, Kim KH, Kim HB et al. Outcome of vancomycin treatment in patients with methicillin-susceptible Staphylococcus aureus bacteremia. Antimicrobial Agents and Chemotherapy 2008: 52:192


Pre-Intervention Period (n=179)

Intervention Period (n=197)


Age, median years (IQR)

64 (54-78)

68 (52-76)



83 (46)

65 (33)



152 (85)

180 (91)



At risk for endocarditis

44 (25)

62 (31)



19 (11)

22 (11)


Cardiovascular prosthesis

31 (17)

32 (16)


Diabetes mellitus

89 (50)

80 (40)



13 (7)

19 (10)



28 (16)

18 (9)



22 (12)

9 (5)


Orthopedic prosthesis

23 (13)

23 (12)



14 (8)

20 (10)


APACHE II Score, mean




Pitt Bacteremia Score, mean




How Acquired




80 (45)

74 (41)

25 (14)

122 (62)

62 (31)

12 (6)




Penicillin allergy

28 (16)

28 (14)


Table 1: Characteristics of Patients with Staphylococcus aureus Bacteremia

Data presented as number of patients (%) unless otherwise specified.

Abbreviations: COPD, chronic obstructive pulmonary disease; MRSA, methicillin-resistant S. aureus.

±Congenital heart defects, artificial heart valves, implanted cardiac device, prior infective endocarditis, rheumatic fever, and intravenous drug abuse.

Community-acquired: within 72 hours of admit in a patient without extensive healthcare contact,; healthcare-associated: within 72 hours of extensive contact with healthcare system (nursing home, organ transplantation, hemodialysis, presence of indwelling intravascular catheter, surgery within 30 days) ;hospital-acquired: >72 hours after hospitalization.

Table 2: Features of Staphylococcus aureus Bacteremia Infection

Pre-Intervention Period (n=179)

Intervention Period (n=197)


Source of Infection

Intravascular catheter

Skin and soft tissue infection





30 (17)

28 (16)

36 (20)

13 (7)

26 (15)

38 (22)

19 (11)

37 (19)

38 (20)

25 (13)

46 (23)

32 (16








75 (42)

70 (36)


Fevers ≥72 hours after antibiotics

5 (3)

0 (0)


Complicated Bacteremia§

156 (87)

155 (79)


Persistent Bacteremia°

6 (3)

3 (2)


Recurrent Bacteremia

5 (3)

11 (6)


Metastatic Infection

26 (15)

20 (10)





38 (21)

27 (15)

11 (6)

55 (28)

30 (15)

25 (13)




Data presented as number of patients (%) unless otherwise specified.

Abbreviations: MRSA, methicillin-resistant S. aureus.

±Congenital heart defects, artificial heart valves, implanted cardiac device, prior infective endocarditis, rheumatic fever, IVDA

Other, respiratory tract infection, endovascular infection other than catheter, urinary tract infection, central nervous system infection

Community-acquired: within 72 hours of admit in a patient without extensive healthcare contact,; healthcare-associated: within 72 hours of extensive contact with healthcare system (nursing home, organ transplantation, hemodialysis, presence of indwelling intravascular catheter, surgery within 30 days); hospital-acquired: >72 hours after hospitalization.

Table 3: Infectious Diseases (ID) Consultation and Adherence to Quality-of-Care Indicators

Pre-Intervention Period (n=179)

Intervention Period (n=197)


ID Consult

176 (98)

193 (98)


Days to ID consult, mean

0 (0-1)

0 (0-1)


Follow-up blood cultures obtained

159 (89)

151 (77)


Early source control

46 (82)

29 (85)


Echocardiography performed

149 (83)

182 (92)



143 (80)

150 (76)



66 (37)

108 (56)


Treatment duration, median days (IQR)

28 (14-42)

29 (19-42)


Appropriate duration§

109 (72)

152 (91)


Appropriate deescalation±

66 (37)

105 (53)


Hours to deescalation, median (IQR)°

64 (42-83)

41 (20-60)


Data presented as number of patients (%) unless otherwise specified

Abbreviations: TTE=transthoracic echocardiogram; TEE= echocardiogram

¶Removal of source of infection (nonpermanent vascular catheter, abscess drainage <72 >hours, or hemodialysis graft); 56 patients in total requiring source removal for the pre-intervention period and 34 patients total for the intervention period

±Applicable only to MSSA patients: de-escalation appropriate if within 24 hours of sensitivity results made available; beta lactams are better for MSSA patients than vancomycin, so if antibiotics are deescalated quicker from vancomycin to beta lactams in MSSA patients, they will have better outcomes

°Time in hours from first antibiotic to de-escalation to B-lactam antibiotics when MSSA and non-allergic patient

§In days, appropriate if patient on antibiotics ≥14 days for uncomplicated bacteremia, ≥28 days for complicated bacteremia, and ≥42 days for endocarditis

Table 4: Outcomes of Patients with Staphylococcus aureus Bacteremia

Pre-Intervention Period (n=179)

Intervention Period (n=197)


Length of hospitalization, median days (IQR)

12 (7-19)

13 (8-21)


Attributable mortality°

28 (48)

25 (66)


All-cause mortality

58 (32)

38 (19)


14 days

18 (31)

16 (42)


30 days

8 (13)

8 (21)


Data presented as number of patients (%) unless otherwise specified

°58 patients died from the pre-intervention period and 38 patients died from the intervention period


Mentor: Amy Slenker, MD


Research Scholars (Acknowledgements and Co-authored Publications), Research Scholars - Posters

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