Infectious Diseases

Assessment of nationally recommended antibiotics for treatment of UTI in U.S.-Mexico border emergency departments

a b s t r a c t

Background: Urinary tract infections seen in the emergency department are commonly treated as an out- patient with oral antibiotics. Given that antibiotics are available for over-the-counter purchase in Mexico, there is speculation that potential misuse and overuse of antibiotics in United States-Mexico border areas could lead to an- tibiotic resistance patterns that would render some Empiric treatments for UTIs less effective. The purpose of this study was to examine the effectiveness of Infectious Disease Society of America guideline-recommended an- tibiotics for treatment of outpatient UTI diagnosed in the emergency department. Data were collected from a county hospital on the U.S.-Mexico border with a metropolitan area of over 2 million people. Secondary analysis included frequency of urine culture isolated, resistance rates of urine pathogens, and prescriber habits.

Methods: This study was a retrospective chart review of adult patients diagnosed and treated for UTI from August 1, 2019, to February 29, 2020. Culture results of included patients were analyzed against in vitro-tested antibiotics. Bac- terial isolate frequency, resistance rates, and prescribing habits were collected.

Results: A total of 985 patient charts were reviewed, of which 520 patients met inclusion criteria for analysis of pre- scribing habits. Of these, 329 positive bacterial culture growths were included in the analysis of antibiotic resistance rates. Oral antibiotics with comparatively lower resistance rates were amoxicillin/clavulanate, cefdinir, cefuroxime, and nitrofurantoin. Oral antibiotics with notably high resistance rates included trimethoprim-sulfamethoxazole (TMP-SMX), tetracycline, ciprofloxacin, levofloxacin, and cephalexin. Nitrofurantoin was prescribed most frequently for outpatient treatment of UTI/cystitis (41.6%) while cephalexin was the most commonly prescribed antibiotic for outpatient treatment of pyelonephritis (50%).

Conclusion: Our findings suggest that, while part of standard IDSA guidelines, fluoroquinolones and TMP-SMX are not ideal Empiric antibiotics for treatment of outpatient UTI in the U.S.-Mexico border region studied due to high resistance rates. Although not listed as first line agents per current IDSA recommendations, 2nd and 3rd generation cephalospo- rins, and amoxicillin/clavulanate would be acceptable options given resistance patterns demonstrated in accordance with IDSA allowance for tailoring selection to local resistance. Nitrofurantoin appears to be consistent with recommen- dations and demonstrates a favorable resistance profile for treatment of outpatient UTI within this region.

(C) 2022

  1. Introduction

urinary tract infections seen in the emergency department (ED) are commonly treated on an outpatient basis with oral antibiotics [1,2]. Even if cultures are performed, patient follow-up with emergency rooms tends to be poor. For this reason, effectiveness of the empiric

* Corresponding author at: Department of Emergency Medicine, 210 N Rick Francis St. Suite 302 F, El Paso, TX 79905, USA.

E-mail address: [email protected] (S.B. Crawford).

antibiotic selection is paramount to avoid possible treatment failure and development of Antimicrobial resistance. The Infectious Disease So- ciety of America (IDSA) provides evidence-based recommendations for outpatient treatment of uncomplicated cystitis and pyelonephritis in women (Table 1) [3]. Due to the over-the-counter availability of antibi- otics in Mexico, there is speculation that potential misuse and overuse of antibiotics in United States-Mexico border areas could create a caus- ative relationship with antibiotic resistance, rendering empiric treat- ments for UTIs less effective.

https://doi.org/10.1016/j.ajem.2022.08.023

0735-6757/(C) 2022

Table 1

Summary of IDSA recommendations for outpatient treatment of UTI in women.

Type of UTI Antibiotic Duration

access hospital with an annual census of 60,000 patients serving a pre- dominantly Hispanic population in the El Paso, Texas, and Ciudad Juarez, Mexico border region. The hospital system’s research compliance depart-

Acute Uncomplicated Cystitis

1st line Nitrofurantoin 100 mg twice daily 5 days TMP-SMX 160/800 mg twice daily 3 days Fosfomycin 3 g Once

2nd line Fluoroquinolones 3 days

ment identified eligible charts for patients diagnosed in the ED during the study period with the following ICD10 codes: N39.0-UTI, N30-Cystitis, N10-Pyelonephritis, N34-Urethritis, R82.81-Pyuria.

Pyelonephritis 1st

Beta-lactams 3-7 days

line Ciprofloxacin 500 mg twice daily 7 days Levofloxacin 750 mg once daily 5 days TMP-SMX 160/800 mg twice daily 14 days

2.2. Patient selection

Patient charts were manually screened and evaluated based on inclu-

2nd line Beta-lactams 10-14

days

IDSA – Infectious Disease Society of America; TMP-SMX -Trimethoprim-Sulfamethoxazole.

Although the development of antibiotic resistance along the United States-Mexico border is a well-documented problem, there is limited available literature investigating its extent and clinical consequences [4-7]. Previous literature has highlighted an increase in antibiotic resis- tance rates amongst U.S.-Mexico border areas over the years, with out- patient urinary quinolone resistant E. coli having shown a 3-fold increase over a six year time period [5]. In addition, antibiotic resistance has been shown to be more common in patients initially treated in Mexico when compared to the United States alone [4]. Furthermore, re- cent travel from Mexico has also been shown to result in a statistically significant failure of empiric antibiotic treatment of UTI in U.S.-Mexico border emergency departments when compared to those who did not report recent travel [6]. With international travel and healthcare utiliza- tion being a common occurrence between U.S.-Mexico border regions, it is imperative to further investigate the extent and clinical consequences of antibiotic resistance amongst these areas and determine if alternative empiric treatment of UTI is warranted.

With over 2 million residents in the region, El Paso, Texas, and Ciudad Juarez, Mexico, make up the second largest United States- Mexico border population and may provide a Representative sample for antibiotic resistance patterns for other border areas [8,9]. Many medications, including antibiotics and injectable formulations of medi- cations, are available for purchase without a prescription in Mexican pharmacies. A 2001 study found approximately half of the El Paso resi- dents surveyed obtained medications from Mexico within the past year [10]. In addition, antibiotics comprise the largest percentage of medica- tions purchased from Ciudad Juarez pharmacies, with 65% being pur- chased without a prescription [11]. Combined with the fact that there are roughly 3 million monthly border crossings between the two areas and cross-border utilization of healthcare services being a relatively common occurrence, there are concerns that overuse and misuse of an- tibiotics may result in decreased efficacy of routinely prescribed antibi- otics for treatment of UTI [12-14]. To our knowledge, this is the first study to investigate and report antibiotic resistance patterns for outpa- tient treatment of patients diagnosed with UTI in emergency depart- ments in the El Paso, Texas, and Ciudad Juarez, Mexico, border region.

The primary purpose of this study was to examine the effectiveness of IDSA guideline-recommended antibiotics for outpatient treatment of acute uncomplicated UTI diagnosed in ED patients in the El Paso, Texas, and Ciudad Juarez, Mexico, border region. Secondary outcomes in- cluded assessing the spectra, frequencies, and resistance rates of urine culture isolates, and prescribing habits of providers in this region.

  1. Methods
    1. Study design

This study was a retrospective chart review of patients diagnosed with and treated for UTI from August 1, 2019, to February 29, 2020, in EDs within the county hospital system. The system includes the main critical

sion and exclusion criteria (Fig. 1). Adult females aged 18 years or older who were diagnosed with UTI, discharged and treated with outpatient antibiotics, and had urine cultures taken with susceptibility testing were included in this study. Excluded patients included individuals who were pregnant, had urological abnormalities, had history of recurrent UTI, had history of immunosuppressive disease or immunosuppressive pharmaco- logic therapy, were admitted to the hospital after diagnosis of UTI, re- ceived treatment from another facility prior to arrival, or were older than 89 years of age. Recurrent UTI was defined as three UTIs in the prior twelve months treated within the county hospital system.

    1. Data collection

Information extracted from charts included patient demographics, date seen in the ED, relevant ICD code, Treatment regimen, and urine culture results with susceptibilities. To assess prescribing habits of healthcare providers, antibiotic identity and duration of therapy were compared to IDSA recommendations. The frequency of multidrug resis- tant organisms (MDROs) relative to total pathogens studied was addi- tionally calculated. MDROs of interest that were documented included methicillin resistant Staphylococcus aureus (MRSA), extended spectrum beta lactamase producing organisms (ESBLs), vancomycin resistant Staphylococcus aureus (VRSA), vancomycin resistant Enterococcus (VRE), and carbapenem resistant Enterobacterales (CRE).

    1. Statistical analysis

Using G*Power version 3.1.9.4, an a priori power analysis was com- pleted to determine study sample size for a t-test with differences in means when study data is compared to a constant. For this two-sided analysis, the effect size (d) was set at 0.5, alpha at 0.05 and power at

0.95. It was determined that a sample size of 326 culture growths was required.

  1. Results
    1. Study cohort

The hospital system’s research compliance department identified 985 charts for adult female patients diagnosed with UTI per ICD10 codes in the ED during the designated study period. Of the 985 patient charts, 520 patients met the study inclusion criteria (Fig. 1). Of these, 196 subjects had cultures producing no growth. All 520 subjects were included in the analysis of prescribing habits of providers. Of the 520 in- cluded patients, 324 patients yielded a combined 329 positive bacterial growth cultures that were included in the analysis of antibiotic resis- tance rates. The average patient age was 46 years old (IQR 28-61). Acute UTI and cystitis made up roughly 90% of total diagnoses (n = 466) and were combined for analysis of lower uncomplicated UTI, with pyelonephritis representing the remaining 10% (n = 54) repre- senting analysis of upper UTI.

    1. Identities and frequencies of organisms cultured

Bacterial isolates and their frequencies of isolation are presented in Table 2. Escherichia coli was the most frequent bacterial isolate, followed

Image of Fig. 1.

Fig. 1.. Flow diagram for patient chart inclusion.

by Klebsiella pneumoniae and Proteus mirabilis. Twenty-six cultured iso- lates were MDROs, making up 7.3% of total isolates. This included one MRSA and 24 ESBL-producing Gram-negative Enterobacterales, includ- ing 24 E. coli isolates and a single Klebsiella pneumoniae isolate. Table 2 summarizes the identities, frequencies, and MDRO characteristics of all cultured isolates.

A summary of antibiotic susceptibility testing is presented in Table 3. Oral antibiotics with notably higher resistance rates included TMP-SMX, doxycycline, cephalexin, and fluoroquinolones, while cefuroxime, cefdinir, nitrofurantoin and amoxicillin/clavulanate had comparatively lower resistance rates. Since the studied institution did not conduct sus- ceptibility testing directly with cephalexin or other oral third-generation cephalosporins such as cefdinir or cefpodoxime, comparable first and third-generation cephalosporins were used as surrogates. Cefazolin was

Table 2

Identities, frequencies, and percentages of total isolates cultured.

Organism cultured

Number cultured

% of Total isolates

ESBL positive

Escherichia coli

268

81.5

23

Klebsiella pneumoniae

32

9.7

1

Proteus mirabilis

8

2.4

0

Citrobacter spp.

6

1.8

0

Enterobacter spp.

3

0.9

0

Enterococcus faecalis

3

0.9

N/A

Kluyvera spp.

2

0.6

0

Pseudomonas aeruginosa

1

0.3

0

Morganella sp.

1

0.3

0

Other Proteus sp.

1

0.3

0

Other Klebsiella sp.

1

0.3

0

MSSA

1

0.3

N/A

MRSA

1

0.3

N/A

GBS

1

0.3

N/A

Totals

329

100

24

MSSA – Methicillin susceptible Staphylococcus aureus. MRSA – Methicillin resistant Staphylococcus aureus. GBS – group B Streptococcus.

ESBL – Extended Spectrum Beta-Lactamase. N/A – Not applicable.

used as a first-generation cephalosporin surrogate for cephalexin; and ceftriaxone, a third-generation cephalosporin, was used as a surrogate for oral third-generation cephalosporins. Due to differences between test- ing platforms, which changed in the middle of our study period, cefazolin susceptibilities were not available for 56 cultured isolates; for these, ceph- alothin was used as a surrogate for first-generation cephalosporin spec- trum of activity.

    1. Prescribing habits

A summary of provider prescribing habits is provided in Table 4. Nitrofurantoin was prescribed most often for outpatient treatment of UTI/cystitis (41.3%) while cephalexin was prescribed most often for out- patient treatment of pyelonephritis (49.1%). Higher than recommended duration of therapy was identified in 57.4% of outpatient antibiotics for treatment of UTI/cystitis, while only 1.1% of prescriptions were lower than the recommended duration. Outpatient antibiotics for treatment of pyelonephritis were prescribed for higher than recommended dura- tion of therapy in 5.8% of patients, while 33.3% of prescriptions were lower than recommended duration. In addition to their outpatient pre- scriptions, 35% of patients diagnosed with pyelonephritis and 13% of pa- tients diagnosed with acute UTI/cystitis were given doses of ceftriaxone in the emergency department prior to discharge. A summary of empiric antibiotic efficacy based on subsequent culture susceptibility patterns is provided in Table 5. Overall resistance rates and likely treatment failure based off subsequent culture susceptibilities patterns was 12.3% for UTI/ cystitis and 20.5% for pyelonephritis.

  1. Discussion

Appropriate empiric selection of antibiotics for treatment of UTI is paramount for preventing treatment failure, minimizing side effects, and preventing development of antibiotic resistance. Compared to cur- rent literature, the results of this study showed comparatively high uropathogen resistance rates to first-generation cephalosporins (20.9%), TMP-SMX (28.5%), and fluoroquinolones (19.6-21.1%), while resistance rates to second and third-generation cephalosporins (12.1%, 7.7%), nitrofurantoin (6.4%), and amoxicillin/clavulanate (7.1%) were comparatively lower [3]. When compared to U.S. national resistance

Table 3

Summary of antibiotic susceptibilities.

Antibiotic

Antibiotic class

Total tested

Not tested

(S)a

(I)b

(R)c

Cultures

n (%)

Cultures

n (%)

Cultures

n (%)

Amoxicillin/Clavulanate

Aminopenicillin + Beta lactamase inhibitor

326

3

260/326 (79.7)

43/326 (13.2)

23/326 (7.1)

Piperacillin/Tazobactam

Extended Spectrum Penicillin + Beta lactamase inhibitor

323

6

308/323 (95.4)

12/323 (3.7)

3/323 (0.9)

Cefazolin/Cephalothind

1st Generation Cephalosporin

321

8

251/321 (78.2)

3/321 (0.9)

67/321 (20.9)

Cefuroxime

2nd Generation Cephalosporin

322

7

278/322 (86.3)

5/322 (1.6)

39/322 (12.1)

Ceftriaxone

3rd Generation Cephalosporin

322

7

297/322 (92.3)

0/322 (0.0)

25/322 (7.7)

Cefepime

4th Generation Cephalosporin

322

7

299/322 (92.9)

0/322 (0.0)

23/322 (7.1)

Ertapenem

Carbapenem

323

6

323/323 (100)

0/323 (0.0)

0/323 (0.0)

Ciprofloxacin

Fluoroquinolone

327

2

257/327 (78.6)

1/327 (0.3)

69/327 (21.1)

Levofloxacin

Fluoroquinolone

327

2

258/327 (78.9)

5/327 (1.5)

64/327 (19.6)

Nitrofurantoin

Nitrofuran

328

1

290/328 (88.4)

17/328 (5.2)

21/328 (6.4)

Tetracycline

Tetracycline

321

8

222/321 (69.2)

4/321 (1.2)

95/321 (29.6)

TMP-SMXe

Sulfonamide

326

3

233/326 (71.5)

0/326 (0.0)

93/326 (28.5)

Note: Percentages calculated as a portion of total tested.

a S, susceptible.

b I, intermediate.

c R, resistant.

d Cefazolin or cephalothin tested as proxy for 1st generation cephalosporins.

e Trimethoprim-sulfamethoxazole.

rates of patient populations with similar community-acquired UTIs, U.S.-Mexico border region uropathogenic antibiotic resistance patterns appear to be higher for most antibiotics; a finding mirrored by the re- sults in this study [15-18]. In contrast, when compared to Mexico, U.S.-Mexico border cities appear to have lower uropathogen resistance rates, with community-acquired Escherichia Coli resistance rates to TMP-SMX and fluoroquinolones being reported as high as 62% and re- sistance rates to first-generation cephalosporins being reported as high as 97% [19,20]. These findings would suggest that, although U.S.- Mexico border cities experience resistance patterns that render some empiric options ineffective, they remain below resistance patterns seen in Mexico.

Per IDSA guidelines, TMP-SMX should not be used empirically for treatment of UTI in areas where resistance rates are greater than 20% [3]. In addition, IDSA guidelines recommend against the usage of fluoro- quinolone monotherapy for the empiric treatment of outpatient pyelo- nephritis if resistance rates exceed 10% [3]. The results of this study are consistent with other existing literature investigating antibiotic resis- tance of U.S.-Mexico border areas, suggesting that routine empiric op- tions for treatment of UTI such as fluoroquinolones and TMP/SMX are suboptimal selections for these regions [5,6]. Despite resistance rates being higher than national comparative data in patient populations with similar community-acquired UTI, the findings of this study simi- larly suggest that nitrofurantoin, second-generation cephalosporins, third-generation cephalosporins, and amoxicillin/clavulanate are pre- ferred empiric options for treating UTI in the El Paso, United States, Ciudad Juarez, Mexico region and possibly other U.S.-Mexico border re- gions due to their low resistance rates when compared to other avail- able antibiotics [15-18]. As mentioned previously, it is possible that potential overuse and misuse of antibiotics acquired without a prescrip- tion in Mexico contributes to resistance rates seen in these regions. In addition, with cross-border utilization being a relatively common occur- rence at the U.S.-Mexico border, it is possible that individuals could be- come colonized with resistant organisms and transmit them upon returning to their country of origin as reported in previous literature [10,11,13,14,21,22]. It is also possible that the social and ecological fac- tors of these areas play some role in resistance patterns seen in U.S.- Mexico border regions. Fuentes et al. found that antibiotics were present in 92% of both water and soil samples taken from areas surrounding the Rio Grande River in the El Paso, Texas, Ciudad Juarez, Mexico border [7]. In addition, authors found that 64.08% of samples contained bacteria resistant to at least two synergistic antibiotic combinations and 14.79% percent were found to be resistant to 20 or more individual

antibiotics [7]. With the Rio Grande River being a common terminal point for wastewater from treatment plants and runoff, it is possible for people inhabiting these areas or using them for recreational pur- poses to become colonized by these resistant pathogens and continue to spread them throughout the community.

When assessing current prescribing habits, only 43.8% (n = 204/466) of patients being treated for UTI/cystitis received IDSA recommended first-line therapy, while 11.1% (n = 6/54) of patients being treated for py- elonephritis received IDSA recommended first-line therapy. In spite of this, the empiric selections picked by providers resulted in resistant cultures for only 12.3% of prescriptions for treatment of UTI/cystitis and 20.5% of pre- scriptions for treatment of pyelonephritis. This is possibly attributed to providers trained at these academic emergency departments being edu- cated on community antibiotic resistance rates, highlighting the impor- tance of provider awareness and utilization of local antibiograms when selecting therapy. TMP-SMX and fluoroquinolones, two first-line empiric options for treatment of both cystitis and pyelonephritis that had two of the highest resistance rates amongst all antibiotics, were only prescribed for 10.3% (n = 48/466) of patients with UTI/cystitis and 11.1% (n = 6/54) of patients with pyelonephritis. However, cephalexin was selected 32.4% of the time by providers for treatment of UTI/cystitis and 50% of the time for treatment of pyelonephritis despite the resistance rates for our compa- rable surrogate first-generation cephalosporin antibiotics totaling to 20.9%. With Medication Safety and cost having been shown to have a large influ- ence on physician prescribing habits, cephalexin’s favorable low cost and side effect profile compared to other empiric options could be a possible reason for its selection [23-25]. Nitrofurantoin was prescribed at the highest rate for UTI/cystitis; while amoxicillin/clavulanate, cefuroxime, and cefdinir combined prescribing rates were only 14.3% for UTI/cystitis and 35.2% for pyelonephritis treated outpatient despite low resistance rates. Given the patterns of susceptibility encountered, further provider education in the region may be appropriate to increase use of these med- ications despite their absence from current ISDA guidelines. These findings also highlight the importance of provider usage of local antibiograms to appropriately prescribe effective empiric antibiotics and prevent treatment failure.

Finally, duration of therapy is an important component of antibiotic stewardship. Providers in our study were found to have prescribed on average a higher days’ supply than IDSA recommends for all antibiotics in the outpatient treatment of UTI/cystitis, while also prescribing a lower days’ supply for outpatient treatment of pyelonephritis. Therapy of insufficient duration can lead to treatment failure, relapse of the con- dition, and increased antibiotic resistance, while excessive duration can

Table 5

Prescriptions under recommended duration (%)

N/Ad

Summary of empiric antibiotic efficacy based on subsequent culture susceptibility results.

UTI Cystitis Pyelonephritis

Empiric antibiotic Prescriptions yielding positive growth cultures

Prescriptions longer than recommended duration (%)

26.0

100.0

100.0

N/Ad N/A 0.0

N/A N/Ad 100.0

N/Ad 33.3

culture yielding pathogen resistant to empiric selection

Prescriptions yielding positive growth cultures

Culture yielding pathogen resistant to empiric selection

Amoxicillin/Clavulanate 2 0 NP NP

Cephalexin 104 18 21 6

N/Ad

0.0

0.0

0.0

N/Ad N/A 75.0

N/A N/Ad 0.0

N/Ad 5.8

Cefuroxime 38 7 11 0

Cefdinir 4 0 1 0

Cefpodoxime 2 0 NP NP

IDSAa Recommended duration of therapy (days)

Ciprofloxacin 18 3 NP NP

Levofloxacin 5 0 3 1

Nitrofurantoin 103 4 1 1

Doxycycline 2 1 1 0

TMP-SMX 7 2 1 0

10-14

10-14

10-14

10-14

10-14

7

5

NR

NRc 14

NRc

Totals 285 35 39 8

Percent resistant to Empiric therapy

Pyelonephritis

Prescriptionsn (%)

12.3% 20.5%

NP – Not prescribed; TMP-SMX – Trimethoprim-Sulfamethoxazole.

0 (0.0)

27 (50.0)

18 (33.3)

1 (1.9)

0 (0.0)

0 (0.0)

4 (7.4)

2 (3.7)

0 (0.0)

2 (3.7)

0 (0.0)

54

lead to unfavorable adverse effects. Spellberg and colleagues found that each day over the recommended duration that antibiotics are pre- scribed increases the patients’ likelihood of experiencing adverse effects by 5% [26]. Additionally, Vogel and colleagues found no therapeutic dif- ference between a 7-day course and a 3-day course of ciprofloxacin for the treatment of acute UTIs. However, the 7-day course had a statisti- cally significant increase in adverse effects [27]. Unnecessary and inap- propriate antibiotics for urinary tract infections have also been shown to increase the likelihood of a patient developing an antibiotic-resistant pathogen within 12 months of initial treatment [28]. Antibiotic practices have been demonstrated on a larger scale to impact the community as a whole; a meta-analysis found that medical practices with longer pre- scription durations and increased Prescription rates had higher resistant rates within their respective areas [28]. A possible reason for antibiotics being prescribed for a longer duration than expected (3-5 days) in Cys- titis/UTI and may be related to automated options within the electronic prescribing system of the medical record. Review of the default dosing and duration options for both cephalexin and nitrofurantoin showed the default options for both to be 7, 10 or 14 days. While individual selec- tion and adjustment are feasible, it is possible that some providers use the default dosing option without taking the additional time for customized prescribing. For example, the electronic prescription system has some of these antibiotic options designed to match pre-determined dosing and quantity packages that are sold at a lower cost by some pharmacies. These kits may not be specifically tailored to the clinical indication. Pro- vider fear of patient complication and poor prognosis has also been asso- ciated with overprescribing, and could thus be another possible explanation for increased duration of antibiotics [25].

UTI/Cystitis

Prescriptions n (%)

IDSAa Recommended duration of therapy (days)

Prescriptions longer than recommended duration (%)

Prescriptions shorter than recommended duration (%)

Aminopenicillin + Beta lactamase inhibitor

1st Generation Cephalosporin 2nd Generation Cephalosporin 3rd Generation Cephalosporin 3rd Generation Cephalosporin Fluoroquinolone Fluoroquinolone

Nitrofuran Tetracycline Sulfonamide Phosphonic Acid

3 (0.6)

3-7

0.0

33.3

151 (32.4)

57 (12.2)

7 (1.5)

3 (0.6)

33 (7.1)

6 (1.3)

194 (41.6)

2 (0.5)

9 (2.0)

1 (0.2)

466

3-7

3-7

3-7

3-7

3

3

5

NRc 3

1

40.4

33.3

0.0

33.3

97.0

100.0

74.2

N/A 66.7

0.0

57.8

0.0

0.0

0.0

0.0

0.0

0.0

2.6

N/Ad 0.0

0.0

1.3

This study has limitations that would affect generalizability. Our findings for the El Paso, Texas-Ciudad Juarez, Mexico, region may not be applicable to all southern border area emergency departments. As the study only examined patients who were discharged from the ED and treated with outpatient antibiotics, our findings may not be gener- alizable to complicated UTIs or those requiring inpatient treatment. An additional limitation is that like many laboratories, the institutional lab- oratory did not directly test susceptibility for cephalexin, which ac- counted for 32.1% of the antibiotics prescribed for UTI/cystitis and 50% of the antibiotics prescribed for pyelonephritis, but instead uses cefazolin or cephalothin as surrogates; a practice recommended by the Clinical and Laboratory Standards Institute (CLSI) guidelines [29]. Simi- larly, cefdinir and cefpodoxime resistance were inferred by resistance testing to ceftriaxone, another third-generation cephalosporin with a similar spectrum of activity. Furthermore, the study’s assessment of

Table 4

Assessment of provider prescribing habits.

Antibiotic

Antibiotic Class

Amoxicillin/Clavulanate

Cephalexin Cefuroxime Cefdinir Cefpodoxime Ciprofloxacin Levofloxacin Nitrofurantoin Doxycycline TMP-SMXb

Fosfomycin Totals

a Infectious Disease Society of America.

b

Trimethoprim-Sulfamethoxazole.

c No IDSA Recommendation.

d Not Applicable.

prescribing habits did not take the cost of the antibiotic, patient’s insur- ance status, or patient’s allergies into account; each of which could im- pact the manner in which antibiotics were prescribed. Finally, patient prior antibiotic usage if self-prescribed and purchased from Mexican pharmacies was not known due to the retrospective nature of the study.

  1. Conclusion

The study findings suggest that, while part of standard IDSA guide- lines, fluoroquinolones and TMP-SMX are not ideal empiric antibiotics for treatment of outpatient UTIs in the studied U.S.-Mexico border re- gion, due to high resistance rates. Although not listed as first line agents, per current IDSA recommendations, 2nd and 3rd generation cephalo- sporins and amoxicillin/clavulanate would be acceptable options given the resistance patterns demonstrated. Nitrofurantoin appears to be con- sistent with recommendations and demonstrates a favorable resistance profile for treatment of outpatient UTI within this region. These findings also highlight the importance of provider usage of local antibiograms to appropriately prescribe effective empiric antibiotics and prevent treat- ment failure.

Sources of funding

This research did not receive any specific grant from funding agen- cies in the public, commercial, or not-for-profit sectors.

Credit authorship contribution statement

William H. Davis: Writing – review & editing, Writing – original draft, Investigation, Formal analysis, Data curation, Conceptualization. Matthew R. Magee: Writing – review & editing, Writing – original draft, Methodology, Investigation, Formal analysis, Data curation, Con- ceptualization. Stormy M. Monks: Writing – review & editing, Writing

  • original draft, Supervision, Formal analysis. K. Aaron Geno: Writing
  • review & editing, Writing – original draft, Formal analysis. Scott B. Crawford: Writing – review & editing, Supervision, Project administra- tion, Methodology, Conceptualization.

Declaration of Competing Interest

All authors declare they have no conflict of interest or relevant finan- cial relationship related to the presented research.

Acknowledgements

None.

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