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 (
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 (
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.