271 Growing Prevalence of Providencia stuartii at Detroit Medical Center, 2005-2009

Saturday, April 2, 2011
Trinity Ballroom (Hilton Anatole)
Kayoko Hayakawa, MD, PhD , Detroit Medical Center, Wayne State University, Detroit, MI
Jason M. Pogue, PharmD , Detroit Medical Center, Wayne State University, Detroit, MI
Paul R. Lephart, PhD , Detroit Medical Center, Wayne State University, Detroit, MI
Sarwan Kumar, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Ryan P. Mynatt, PharmD , Detroit Medical Center, Wayne State University, Detroit, MI
Jing J. Zhao, PharmD , Detroit Medical Center, Wayne State University, Detroit, MI
Teena Chopra, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Sorabh Dhar, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Jack D. Sobel, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Keith S. Kaye, MD, MPH , Detroit Medical Center, Wayne State University, Detroit, MI
Dror Marchaim, MD , Detroit Medical Center, Wayne State University, Detroit, MI

Background: Providencia stuartii is usually a urinary pathogen isolated from patients residing in healthcare facilities and can also be a cause of bacteremia. P. stuartii is associated with both intrinsic and acquired resistance determinants. Tigecycline and colistin are sometimes the only available agents that retain activity against certain multi-drug resistant (MDR) Gram-negative pathogens, but both have poor activity against Providencia spp. 

Objective: The objective of this study was to determine if increasing use of tigecycline and colistin in our health system was associated with increasing prevalence of P. stuartii.

Methods: Trend analysis of the prevalence of P. stuartii at the Detroit Medical Center (DMC), an 8-hospital healthcare system with over 2,200 inpatient beds, was conducted from 2005-2009. A broth micro-dilution MicroscanŽ automated system was used for species identification and antibiotic susceptibility testing. Antibiograms and all cultures processing were conducted according to CLSI criteria. Defined daily doses (DDD) of tigecycline and colistin for the study period were obtained from pharmacy data.

Results: During the 5-year study period, the prevalence of P. stuartii at the DMC significantly increased (Table) (p for trend < 0.001). Tigecycline's and colistin's DDDs also increased significantly during the study period (p for trend < 0.001). The increase in P. stuartii was associated with the increased use of colistin, although this was not statistically significant (r=0.6, p=0.28). No significant association was found between the increase of P. stuartii and the use of tigecycline.

 Conclusions: The prevalence of P. stuartii at the DMC increased significantly during the 5-year study period and was correlated with the increased use of colistin. This association might be due to the broad spectrum activity of colistin against gram-negative bacteria, and lack of activity against P. stuartii.

Table I - P. stuartii antibiogram, Detroit Medical Center, 2005-2009

Yr

P. stuartii No. of isolates

P. stuartii  No. of cases/1,000 Pt days

Susceptibility prevalence (%)

DDD

AMP

Pip/ Tazo

CZL

CRX

CTR

CAZ

CFP

AZT

MER

AMK

GEN

CIP

Trim/ Sulfa

COL DDD

TIG DDD

2005

168

0.52

12

96

9

53

98

95

98

98

100

100

35

34

65

0

0

2006

171

0.5

18

95

17

60

98

90

98

95

100

99

47

32

66

185

363

2007

139

0.41

19

98

14

61

98

96

96

90

100

98

43

32

71

1994

1745

2008

217

0.65

9

98

8

46

99

95

93

96

100

100

41

30

59

5138

1059

2009

288

0.91

16

98

12

44

93

95

93

94

100

100

40

28

60

4459

1105

AMP: Ampicillin; Pip/Tazo: Piperacillin/Tazobactam; CZL: Cefazolin; CRX: Cefuroxime; CTR: Ceftriaxone; CAZ: Ceftazidime; CFP: Cefepime; AZT: Aztreonam; MER: Meropenem; AMK: Amikacin; GEN: Gentamicin; CIP: Ciprofloxacin; Trim/Sulfa:Trimethoprim/Sulfamethoxazole; COL: Colistin; TIG: Tigecycline.