Emergency Department Antimicrobial Treatment of Uncomplicated Urinary Tract Infections in Regions with Resistance

Tools



Introduction

Background

Current recommendations for treatment of uncomplicated urinary tract infections are based on in-vitro susceptibility.

Objective

To determine whether empiric antibiotic management of uncomplicated urinary tract infections presenting to the Emergency department is justified by our in-vivo Escherichia coli resistance rates. The study was conducted at an inner city hospital in the Bronx seeing 100,000 patients per year.

Methods

A retrospective analysis of 1050 urine cultures of patients presenting to the emergency department over a 1 year period was performed. Excluded patients were those less than 18 years of age or older than 65 years of age, patients with immunosuppression, diabetes mellitus, neurogenic bladder or recent admission to hospital. There were 752 patients that met inclusion criteria.

Results

There were 323 positive urine cultures (46.9%) and 365 (53.1%) negative.  Escherichia coli represented 247 (35.9%) of the positive urinary isolates.  The resistance rate for Escherichia coli to trimpethoprim-sulfamethoxazole was found to be 24.9%.

Conclusion

Empriric antibiotic treatment of urinary tract infection with a floroquinolone is justified in this patient population.  Recommendations have been made to use a floroquinolone for the empiric management of UTI in regions with rates of resistance to Escherichia coli >20%. The current recommendations based on in-vitro susceptibility are supported by our in-vivo susceptibility data.

Uncomplicated community-acquired urinary tract infections (UTI’s) are among the most common infections in women. 1   UTI accounts for over 6 million patient visits to physicians per year in the United States, approximately one fifth of those visits are to Emergency Departments.  Current management of these infections is usually empiric without susceptibility testing to guide therapy. 1   Antimicrobial resistance among pathogens has been increasing, leading to specific recommendations for antimicrobial therapy in regions with high rates of resistance. 3 4   The most significant change in resistance among uropathogens has been the increase in prevalence of resistance to trimethoprim-sulfamethoxazole (TMP-SMX). 1   Due to such an increase in resistance TMP-SMX is no longer the current drug of choice in specific regions. 1

The reports identifying regions of resistance have focused on in vitro resistance of uropathogens to TMP-SMX, the clinical significance of this resistance has not been well studied. 4 5   Therefore implications for health care providers are not yet clear.  The objective of this study is to evaluate resistance rates for the community and assess efficacy of empiric antimicrobial therapy based on susceptibility testing.

Methods

Data Extraction

Data on physician emergency department empiric antimicrobial therapy and prescription behavior were derived from the electronic patient record system (Horizon Patient Folder).  We searched the database files for women aged 18-65 who visited the emergency department from January 2005 to January 2006 and were diagnosed with acute cystitis [International Classification of Diseases, Ninth Revision (ICD-9) code 590-0] or UTI, site unspecified (ICD-9 599-0) and treated empirically with an antibiotic.  Patients with urologic structural abnormalities, diabetes mellitus, immuno-suppression, or recent hospitalizations were excluded.

Susceptibility Data/Prescription Data

Susceptibility data and prescription data for the period of January 2005 to January 2006 was retrieved from electronic files from the HBO system computers at St. Barnabas Hospital Bronx NY.

Table 1. Distribution of UTI Culture Types
UTI FREQUENCY PERCENT
Positive 323 46.9
E. coli 247 35.9
E. faecalis 2 0.3
Staph. saprophyticus 11 1.6
Staph. Aureus 9 1.3
Staph. unknown 7 1.0
Multiple 14 2.0
Klebsiella pneumoniae 12 1.7
Hemolytic Strep, grp B 8 1.2
Hemolytic Strep, grp A 1 0.1
Proteus mirabilis 7 1.0
C.koseri 2 0.3
Negative 365 53.1
Total 688 100.0

 

Table 2. Distribution of Culture Type in UTI+ Cases
UTI FREQUENCY PERCENT
E. coli 247 76.5
E. faecal 2 0.6
Staph. saprophyticus 11 3.4
Staph. Aureus 9 2.8
Staph. unknown 7 2.2
Multiple 14 4.3
Klebsiella pneumoniae 12 3.7
Hemolytic Strep, grp B 8 2.5
Hemolytic Strep, grp A 1 0.3
Proteus mirabilis 7 2.2
STD 3 0.9
C. koseri 2 0.6
Total 323 100.0

 

Table 3. Number and Percentage of Resistant Isolates in UTI+ Cases
BACT
RIM
CEPH
ALO
SPORIN
QUIN
OLONE
PENI
CILLIN
AMINO
GLYCO
SIDE
AZTRE
ONAM
ERYTH
ROMY
CIN
IMI
PENEM
TOTAL
POSITIVE
SAMPLES
Escherichia 66 6 6 129 9 2 0 0 24 .9
E. coli, E. faecalis 26.5% 2.4% 2.4% 51.8% 3.6% 0.8% 0.0% 0.0%
Staphylococcus 2 18 7 27 1 0 15 1 27
S.aureus, S.saprophyticus, S. unknown 7.4% 66.7% 25.9% 100.0% 3.7% 0.0% 55.6% 3.7%
Multiple 1 0 0 2 0 0 0 0 14
multiple organisms identified 7.1% 0.0% 0.0% 14.3% 0.0% 0.0% 0.0% 0.0%
Klebsiella pneumoniae 4 0 0 12 0 0 0 0 12
33.3% 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0%
Other 0 0 0 4 0 4 0 0 21
Hemolytic strep group B, group A, P. mirabilis, STD, C.koseri 0.0% 0.0% 0.0% 19.0% 0.0% 19.0% 0.0% 0.0%
Total Resistant Isolates 73 24 13 174 10 6 15 1 323
% of total resistant isolates 22.6% 7.4% 4.0% 53.9% 3.1% 1.9% 4.6% 0.3%

 

Table 4.Outpatient Prescriptions of UTI+ Cases
PRESCRIPTION FREQUENCY PERCENT
Levaquin 243 75.2
Levaquin+any other drug 24 7.4
Vantin 12 3.7
Bactrim 8 2.5
Ciprofloxicin 7 2.2
Other (macrobid, keflex, augmentin, pyr, reglan) 10 3.1
None 19 5.9
Total 323 100.0

Table IV: summarizes outpatient prescriptions provided to patients being discharged from Emergency Department.  Levofloxacin remains the most common outpatient prescription (82.6%) provided in our institution.  Levofloxacin has become the most common prescription prescribed by Emergency Department for management of uncomplicated UTI’s’

Discussion

The susceptibility patterns of uropathogens causing acute uncomplicated UTI’s’ are changing, reducing the safety and accuracy of empiric therapy for affected patients. 1   To complicate matters this change is not uniform from region to region.  The Infectious Disease Society of America (IDSA) guidelines published for treatment of uncomplicated UTI are based on in-vitro susceptibility data, this data has come into question in regard to its application clinically.

The guidelines suggest use of this in-vitro data susceptibility to guide management.  Much of this in-vitro data comes from laboratory based surveys that often do not reflect sex, age, clinical syndrome, or location (inpatient versus outpatient) of the patients from whom the urine specimen was collected.

Therefore the reported rates of resistance may vary depending on whether the study sample consists primarily of outpatients with uncomplicated UTI’s or patients with complicated nonsocial UTI’s.

The data presented here clearly define the study sample as women with uncomplicated community acquired UTI.  The data shows that our population can be classified as a high risk population for Escherichia coli Trimethoprim-Sulfamethoxazole resistance (24.9% in-vivo).  In this population the use of floroquinolones is certainly recommended and justified based on results.

In light of the growing Floroquinolone resistance, the feasibility or performing in-vivo studies in areas with in-vitro resistance to trimethoprim-sulfamethoxazole should be evaluated.  This may further guide our empiric antimicrobial management of community acquired urinary tract infections in women.

The results of our data agree with current in-vitro resistance rates for this region.  More in-vivo studies would have to be completed in order to use the in-vitro resistance rates with higher certainty.

Prescription outpatient practice by emergency medicine physicians treated 93% isolates. Floroquinolones were prescribed 82% of the time for treatment of community acquired urinary tract infections.  Resistance rates of Escherichia coli to Floroquinolones are increasing from reported results in 2002 (2%).  Our study calculated a 6% resistance rate to Floroquinolones.  Current strategies to target empirical antibiotic prescribing in clinically suspected, uncomplicated UTI require review.

References

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