Discordant Antibiotics in Pediatric UTI

Urinary tract infections (UTIs) are one of the most common reasons for pediatric hospitalizations.1 Bacterial infections require prompt treatment with appropriate antimicrobial agents. Results from culture and susceptibility testing, however, are often unavailable until 48 hours after initial presentation. Therefore, the clinician must select antimicrobials empirically, basing decisions on likely pathogens and local resistance patterns.2 This decision is challenging because the effect of treatment delay on clinical outcomes is difficult to determine and resistance among uropathogens is increasing. Resistance rates have doubled over the past several years.3, 4 For common first‐line antibiotics, such as ampicillin and trimethoprim‐sulfamethoxazole, resistance rates for Escherichia coli, the most common uropathogen, exceed 25%.4, 5 While resistance to third‐generation cephalosporins remains low, rates in the United States have increased from <1% in 1999 to 4% in 2010. International data shows much higher resistance rates for cephalosporins in general.6, 7 This high prevalence of resistance may prompt the use of broad‐spectrum antibiotics for patients with UTI. For example, the use of third‐generation cephalosporins for UTI has doubled in recent years.3 Untreated, UTIs can lead to serious illness, but the consequences of inadequate initial antibiotic coverage are unknown.8, 9

Discordant antibiotic therapy, initial antibiotic therapy to which the causative bacterium is not susceptible, occurs in up to 9% of children hospitalized for UTI.10 However, there is reason to believe that discordant therapy may matter less for UTIs than for infections at other sites. First, in adults hospitalized with UTIs, discordant initial therapy did not affect the time to resolution of symptoms.11, 12 Second, most antibiotics used to treat UTIs are renally excreted and, thus, antibiotic concentrations at the site of infection are higher than can be achieved in the serum or cerebrospinal fluid.13 The Clinical and Laboratory Standard Institute has acknowledged that traditional susceptibility breakpoints may be too conservative for some non‐central nervous system infections; such as non‐central nervous system infections caused by Streptococcus pneumoniae.14

As resistance rates increase, more patients are likely to be treated with discordant therapy. Therefore, we sought to identify the clinical consequences of discordant antimicrobial therapy for patients hospitalized with a UTI.

METHODS

RESULTS

Of the initial 460 cases with positive urine culture growth at any time during admission, 216 met inclusion criteria for a laboratory‐confirmed UTI from urine culture completed at admission. The median age was 2.46 years (IQR: 0.27,8.89). In the study population, 25.0% were male, 31.0% were receiving prophylactic antibiotics, 13.0% had any grade of VUR, and 16.7% had abnormal GU anatomy (Table 1). A total of 82.4% of patients were treated with concordant initial therapy, 10.2% with discordant initial therapy, and 7.4% received delayed initial antibiotic therapy. There were no significant differences between the groups for any of the covariates. Discordant antibiotic cases ranged from 4.9% to 21.7% across hospitals.

The most common causative organisms were E. coli (65.7%) and Klebsiella spp (9.7%) (Table 2). The most common initial antibiotics were a third‐generation cephalosporin (39.1%), combination of ampicillin and a third‐ or fourth‐generation cephalosporin (16.7%), and combination of ampicillin with gentamicin (11.1%). A third‐generation cephalosporin was the initial antibiotic for 46.1% of the E. coli and 56.9% of Klebsiella spp UTIs. Resistance to third‐generation cephalosporins but carbapenem susceptibility was noted for 4.5% of E. coli and 7.7% of Klebsiella spp isolates. Patients with UTIs caused by Klebsiella spp, mixed organisms, and Enterobacter spp were more likely to receive discordant antibiotic therapy. Patients with Enterobacter spp and mixed‐organism UTIs were more likely to have delayed antibiotic therapy. Nineteen patients (8.8%) had positive blood cultures. Fifteen (6.9%) required intensive care unit (ICU) admission during hospitalization.

Unadjusted results are shown in Supporting Appendix 1, in the online version of this article. In the adjusted analysis, discordant antibiotic therapy was associated with a significantly longer LOS, compared with concordant therapy for all UTIs and for all UTIs caused by a single organism (Table 3). In adjusted analysis, discordant therapy was also associated with a 3.1 day (IQR: 2.0, 4.7) longer length of stay compared with concordant therapy for all E. coli UTIs.

Time to fever resolution was analyzed for patients with a documented fever at presentation for each treatment subgroup. One hundred thirty‐six patients were febrile at admission and 122 were febrile beyond the first recorded vital signs. Fever was present at admission in 60% of the concordant group and 55% of the discordant group (P = 0.6). The median duration of fever was 48 hours for the concordant group (n = 107; IQR: 24, 240) and 78 hours for the discordant group (n = 12; IQR: 48, 132). All patients were afebrile at discharge. Differences in fever duration between treatment groups were not statistically significant (P = 0.7).

DISCUSSION

Across 5 children's hospitals, 1 out of every 10 children hospitalized for UTI received discordant initial antibiotic therapy. Children receiving discordant antibiotic therapy had a 1.8 day longer LOS when compared with those on concordant therapy. However, there was no significant difference in time to fever resolution between the groups, suggesting that the increase in LOS was not explained by increased fever duration.

The overall rate of discordant therapy in this study is consistent with prior studies, as was the more common association of discordant therapy with non‐E. coli UTIs.10 According to the Kids' Inpatient Database 2009, there are 48,100 annual admissions for patients less than 20 years of age with a discharge diagnosis code of UTI in the United States.1 This suggests that nearly 4800 children with UTI could be affected by discordant therapy annually.

Children treated with discordant antibiotic therapy had a significantly longer LOS compared to those treated with concordant therapy. However, differences in time to fever resolution between the groups were not statistically significant. While resolution of fever may suggest clinical improvement and adequate empiric therapy, the lack of association with antibiotic concordance was not unexpected, since the relationship between fever resolution, clinical improvement, and LOS is complex and thus challenging to measure.21 These results support the notion that fever resolution alone may not be an adequate measure of clinical response.

It is possible that variability in discharge decision‐making may contribute to increased length of stay. Some clinicians may delay a patient's discharge until complete resolution of symptoms or knowledge of susceptibilities, while others may discharge patients that are still febrile and/or still receiving empiric antibiotics. Evidence‐based guidelines that address the appropriate time to discharge a patient with UTI are lacking. The American Academy of Pediatrics provides recommendations for use of parenteral antibiotics and hospital admission for patients with UTI, but does not address discharge decision‐making or patient management in the setting of discordant antibiotic therapy.2, 21

This study must be interpreted in the context of several limitations. First, our primary and secondary outcomes, LOS and fever duration, were surrogate measures for clinical response. We were not able to measure all clinical factors that may contribute to LOS, such as the patient's ability to tolerate oral fluids and antibiotics. Also, there may have been too few patients to detect a clinically important difference in fever duration between the concordant and discordant groups, especially for individual organisms. Although we did find a significant difference in LOS between patients treated with concordant compared with discordant therapy, there may be residual confounding from unobserved differences. This confounding, in conjunction with the small sample size, may cause us to underestimate the magnitude of the difference in LOS resulting from discordant therapy. Second, short‐term outcomes such as ICU admission were not investigated in this study; however, the proportion of patients admitted to the ICU in our population was quite small, precluding its use as a meaningful outcome measure. Third, the potential benefits to patients who were not exposed to unnecessary antibiotics, or harm to those that were exposed, could not be measured. Finally, our study was obtained using data from 5 free‐standing tertiary care pediatric facilities, thereby limiting its generalizability to other settings. Still, our rates of prophylactic antibiotic use, VUR, and GU abnormalities are similar to others reported in tertiary care children's hospitals, and we accounted for these covariates in our model.2225

As the frequency of infections caused by resistant bacteria increase, so will the number of patients receiving discordant antibiotics for UTI, compounding the challenge of empiric antimicrobial selection. Further research is needed to better understand how discordant initial antibiotic therapy contributes to LOS and whether it is associated with adverse short‐ and long‐term clinical outcomes. Such research could also aid in weighing the risk of broader‐spectrum prescribing on antimicrobial resistance patterns. While we identified an association between discordant initial antibiotic therapy and LOS, we were unable to determine the ideal empiric antibiotic therapy for patients hospitalized with UTI. Further investigation is needed to inform local and national practice guidelines for empiric antibiotic selection in patients with UTIs. This may also be an opportunity to decrease discordant empiric antibiotic selection, perhaps through use of antibiograms that stratify patients based on known factors, to lead to more specific initial therapy.

CONCLUSIONS

This study demonstrates that discordant antibiotic selection for UTI at admission is associated with longer hospital stay, but not fever duration. The full clinical consequences of discordant therapy, and the effects on length of stay, need to be better understood. Our findings, taken in combination with careful consideration of patient characteristics and prior history, may provide an opportunity to improve the hospital care for patients with UTIs.

Urinary tract infections (UTIs) are one of the most common reasons for pediatric hospitalizations.1 Bacterial infections require prompt treatment with appropriate antimicrobial agents. Results from culture and susceptibility testing, however, are often unavailable until 48 hours after initial presentation. Therefore, the clinician must select antimicrobials empirically, basing decisions on likely pathogens and local resistance patterns.2 This decision is challenging because the effect of treatment delay on clinical outcomes is difficult to determine and resistance among uropathogens is increasing. Resistance rates have doubled over the past several years.3, 4 For common first‐line antibiotics, such as ampicillin and trimethoprim‐sulfamethoxazole, resistance rates for Escherichia coli, the most common uropathogen, exceed 25%.4, 5 While resistance to third‐generation cephalosporins remains low, rates in the United States have increased from <1% in 1999 to 4% in 2010. International data shows much higher resistance rates for cephalosporins in general.6, 7 This high prevalence of resistance may prompt the use of broad‐spectrum antibiotics for patients with UTI. For example, the use of third‐generation cephalosporins for UTI has doubled in recent years.3 Untreated, UTIs can lead to serious illness, but the consequences of inadequate initial antibiotic coverage are unknown.8, 9

Discordant antibiotic therapy, initial antibiotic therapy to which the causative bacterium is not susceptible, occurs in up to 9% of children hospitalized for UTI.10 However, there is reason to believe that discordant therapy may matter less for UTIs than for infections at other sites. First, in adults hospitalized with UTIs, discordant initial therapy did not affect the time to resolution of symptoms.11, 12 Second, most antibiotics used to treat UTIs are renally excreted and, thus, antibiotic concentrations at the site of infection are higher than can be achieved in the serum or cerebrospinal fluid.13 The Clinical and Laboratory Standard Institute has acknowledged that traditional susceptibility breakpoints may be too conservative for some non‐central nervous system infections; such as non‐central nervous system infections caused by Streptococcus pneumoniae.14

As resistance rates increase, more patients are likely to be treated with discordant therapy. Therefore, we sought to identify the clinical consequences of discordant antimicrobial therapy for patients hospitalized with a UTI.

METHODS

RESULTS

Of the initial 460 cases with positive urine culture growth at any time during admission, 216 met inclusion criteria for a laboratory‐confirmed UTI from urine culture completed at admission. The median age was 2.46 years (IQR: 0.27,8.89). In the study population, 25.0% were male, 31.0% were receiving prophylactic antibiotics, 13.0% had any grade of VUR, and 16.7% had abnormal GU anatomy (Table 1). A total of 82.4% of patients were treated with concordant initial therapy, 10.2% with discordant initial therapy, and 7.4% received delayed initial antibiotic therapy. There were no significant differences between the groups for any of the covariates. Discordant antibiotic cases ranged from 4.9% to 21.7% across hospitals.

The most common causative organisms were E. coli (65.7%) and Klebsiella spp (9.7%) (Table 2). The most common initial antibiotics were a third‐generation cephalosporin (39.1%), combination of ampicillin and a third‐ or fourth‐generation cephalosporin (16.7%), and combination of ampicillin with gentamicin (11.1%). A third‐generation cephalosporin was the initial antibiotic for 46.1% of the E. coli and 56.9% of Klebsiella spp UTIs. Resistance to third‐generation cephalosporins but carbapenem susceptibility was noted for 4.5% of E. coli and 7.7% of Klebsiella spp isolates. Patients with UTIs caused by Klebsiella spp, mixed organisms, and Enterobacter spp were more likely to receive discordant antibiotic therapy. Patients with Enterobacter spp and mixed‐organism UTIs were more likely to have delayed antibiotic therapy. Nineteen patients (8.8%) had positive blood cultures. Fifteen (6.9%) required intensive care unit (ICU) admission during hospitalization.

Unadjusted results are shown in Supporting Appendix 1, in the online version of this article. In the adjusted analysis, discordant antibiotic therapy was associated with a significantly longer LOS, compared with concordant therapy for all UTIs and for all UTIs caused by a single organism (Table 3). In adjusted analysis, discordant therapy was also associated with a 3.1 day (IQR: 2.0, 4.7) longer length of stay compared with concordant therapy for all E. coli UTIs.

Time to fever resolution was analyzed for patients with a documented fever at presentation for each treatment subgroup. One hundred thirty‐six patients were febrile at admission and 122 were febrile beyond the first recorded vital signs. Fever was present at admission in 60% of the concordant group and 55% of the discordant group (P = 0.6). The median duration of fever was 48 hours for the concordant group (n = 107; IQR: 24, 240) and 78 hours for the discordant group (n = 12; IQR: 48, 132). All patients were afebrile at discharge. Differences in fever duration between treatment groups were not statistically significant (P = 0.7).

DISCUSSION

Across 5 children's hospitals, 1 out of every 10 children hospitalized for UTI received discordant initial antibiotic therapy. Children receiving discordant antibiotic therapy had a 1.8 day longer LOS when compared with those on concordant therapy. However, there was no significant difference in time to fever resolution between the groups, suggesting that the increase in LOS was not explained by increased fever duration.

The overall rate of discordant therapy in this study is consistent with prior studies, as was the more common association of discordant therapy with non‐E. coli UTIs.10 According to the Kids' Inpatient Database 2009, there are 48,100 annual admissions for patients less than 20 years of age with a discharge diagnosis code of UTI in the United States.1 This suggests that nearly 4800 children with UTI could be affected by discordant therapy annually.

Children treated with discordant antibiotic therapy had a significantly longer LOS compared to those treated with concordant therapy. However, differences in time to fever resolution between the groups were not statistically significant. While resolution of fever may suggest clinical improvement and adequate empiric therapy, the lack of association with antibiotic concordance was not unexpected, since the relationship between fever resolution, clinical improvement, and LOS is complex and thus challenging to measure.21 These results support the notion that fever resolution alone may not be an adequate measure of clinical response.

It is possible that variability in discharge decision‐making may contribute to increased length of stay. Some clinicians may delay a patient's discharge until complete resolution of symptoms or knowledge of susceptibilities, while others may discharge patients that are still febrile and/or still receiving empiric antibiotics. Evidence‐based guidelines that address the appropriate time to discharge a patient with UTI are lacking. The American Academy of Pediatrics provides recommendations for use of parenteral antibiotics and hospital admission for patients with UTI, but does not address discharge decision‐making or patient management in the setting of discordant antibiotic therapy.2, 21

This study must be interpreted in the context of several limitations. First, our primary and secondary outcomes, LOS and fever duration, were surrogate measures for clinical response. We were not able to measure all clinical factors that may contribute to LOS, such as the patient's ability to tolerate oral fluids and antibiotics. Also, there may have been too few patients to detect a clinically important difference in fever duration between the concordant and discordant groups, especially for individual organisms. Although we did find a significant difference in LOS between patients treated with concordant compared with discordant therapy, there may be residual confounding from unobserved differences. This confounding, in conjunction with the small sample size, may cause us to underestimate the magnitude of the difference in LOS resulting from discordant therapy. Second, short‐term outcomes such as ICU admission were not investigated in this study; however, the proportion of patients admitted to the ICU in our population was quite small, precluding its use as a meaningful outcome measure. Third, the potential benefits to patients who were not exposed to unnecessary antibiotics, or harm to those that were exposed, could not be measured. Finally, our study was obtained using data from 5 free‐standing tertiary care pediatric facilities, thereby limiting its generalizability to other settings. Still, our rates of prophylactic antibiotic use, VUR, and GU abnormalities are similar to others reported in tertiary care children's hospitals, and we accounted for these covariates in our model.2225

As the frequency of infections caused by resistant bacteria increase, so will the number of patients receiving discordant antibiotics for UTI, compounding the challenge of empiric antimicrobial selection. Further research is needed to better understand how discordant initial antibiotic therapy contributes to LOS and whether it is associated with adverse short‐ and long‐term clinical outcomes. Such research could also aid in weighing the risk of broader‐spectrum prescribing on antimicrobial resistance patterns. While we identified an association between discordant initial antibiotic therapy and LOS, we were unable to determine the ideal empiric antibiotic therapy for patients hospitalized with UTI. Further investigation is needed to inform local and national practice guidelines for empiric antibiotic selection in patients with UTIs. This may also be an opportunity to decrease discordant empiric antibiotic selection, perhaps through use of antibiograms that stratify patients based on known factors, to lead to more specific initial therapy.

CONCLUSIONS

This study demonstrates that discordant antibiotic selection for UTI at admission is associated with longer hospital stay, but not fever duration. The full clinical consequences of discordant therapy, and the effects on length of stay, need to be better understood. Our findings, taken in combination with careful consideration of patient characteristics and prior history, may provide an opportunity to improve the hospital care for patients with UTIs.

Urinary tract infections (UTIs) are one of the most common reasons for pediatric hospitalizations.1 Bacterial infections require prompt treatment with appropriate antimicrobial agents. Results from culture and susceptibility testing, however, are often unavailable until 48 hours after initial presentation. Therefore, the clinician must select antimicrobials empirically, basing decisions on likely pathogens and local resistance patterns.2 This decision is challenging because the effect of treatment delay on clinical outcomes is difficult to determine and resistance among uropathogens is increasing. Resistance rates have doubled over the past several years.3, 4 For common first‐line antibiotics, such as ampicillin and trimethoprim‐sulfamethoxazole, resistance rates for Escherichia coli, the most common uropathogen, exceed 25%.4, 5 While resistance to third‐generation cephalosporins remains low, rates in the United States have increased from <1% in 1999 to 4% in 2010. International data shows much higher resistance rates for cephalosporins in general.6, 7 This high prevalence of resistance may prompt the use of broad‐spectrum antibiotics for patients with UTI. For example, the use of third‐generation cephalosporins for UTI has doubled in recent years.3 Untreated, UTIs can lead to serious illness, but the consequences of inadequate initial antibiotic coverage are unknown.8, 9

Discordant antibiotic therapy, initial antibiotic therapy to which the causative bacterium is not susceptible, occurs in up to 9% of children hospitalized for UTI.10 However, there is reason to believe that discordant therapy may matter less for UTIs than for infections at other sites. First, in adults hospitalized with UTIs, discordant initial therapy did not affect the time to resolution of symptoms.11, 12 Second, most antibiotics used to treat UTIs are renally excreted and, thus, antibiotic concentrations at the site of infection are higher than can be achieved in the serum or cerebrospinal fluid.13 The Clinical and Laboratory Standard Institute has acknowledged that traditional susceptibility breakpoints may be too conservative for some non‐central nervous system infections; such as non‐central nervous system infections caused by Streptococcus pneumoniae.14

As resistance rates increase, more patients are likely to be treated with discordant therapy. Therefore, we sought to identify the clinical consequences of discordant antimicrobial therapy for patients hospitalized with a UTI.

METHODS

RESULTS

Of the initial 460 cases with positive urine culture growth at any time during admission, 216 met inclusion criteria for a laboratory‐confirmed UTI from urine culture completed at admission. The median age was 2.46 years (IQR: 0.27,8.89). In the study population, 25.0% were male, 31.0% were receiving prophylactic antibiotics, 13.0% had any grade of VUR, and 16.7% had abnormal GU anatomy (Table 1). A total of 82.4% of patients were treated with concordant initial therapy, 10.2% with discordant initial therapy, and 7.4% received delayed initial antibiotic therapy. There were no significant differences between the groups for any of the covariates. Discordant antibiotic cases ranged from 4.9% to 21.7% across hospitals.

The most common causative organisms were E. coli (65.7%) and Klebsiella spp (9.7%) (Table 2). The most common initial antibiotics were a third‐generation cephalosporin (39.1%), combination of ampicillin and a third‐ or fourth‐generation cephalosporin (16.7%), and combination of ampicillin with gentamicin (11.1%). A third‐generation cephalosporin was the initial antibiotic for 46.1% of the E. coli and 56.9% of Klebsiella spp UTIs. Resistance to third‐generation cephalosporins but carbapenem susceptibility was noted for 4.5% of E. coli and 7.7% of Klebsiella spp isolates. Patients with UTIs caused by Klebsiella spp, mixed organisms, and Enterobacter spp were more likely to receive discordant antibiotic therapy. Patients with Enterobacter spp and mixed‐organism UTIs were more likely to have delayed antibiotic therapy. Nineteen patients (8.8%) had positive blood cultures. Fifteen (6.9%) required intensive care unit (ICU) admission during hospitalization.

Unadjusted results are shown in Supporting Appendix 1, in the online version of this article. In the adjusted analysis, discordant antibiotic therapy was associated with a significantly longer LOS, compared with concordant therapy for all UTIs and for all UTIs caused by a single organism (Table 3). In adjusted analysis, discordant therapy was also associated with a 3.1 day (IQR: 2.0, 4.7) longer length of stay compared with concordant therapy for all E. coli UTIs.

Time to fever resolution was analyzed for patients with a documented fever at presentation for each treatment subgroup. One hundred thirty‐six patients were febrile at admission and 122 were febrile beyond the first recorded vital signs. Fever was present at admission in 60% of the concordant group and 55% of the discordant group (P = 0.6). The median duration of fever was 48 hours for the concordant group (n = 107; IQR: 24, 240) and 78 hours for the discordant group (n = 12; IQR: 48, 132). All patients were afebrile at discharge. Differences in fever duration between treatment groups were not statistically significant (P = 0.7).

DISCUSSION

Across 5 children's hospitals, 1 out of every 10 children hospitalized for UTI received discordant initial antibiotic therapy. Children receiving discordant antibiotic therapy had a 1.8 day longer LOS when compared with those on concordant therapy. However, there was no significant difference in time to fever resolution between the groups, suggesting that the increase in LOS was not explained by increased fever duration.

The overall rate of discordant therapy in this study is consistent with prior studies, as was the more common association of discordant therapy with non‐E. coli UTIs.10 According to the Kids' Inpatient Database 2009, there are 48,100 annual admissions for patients less than 20 years of age with a discharge diagnosis code of UTI in the United States.1 This suggests that nearly 4800 children with UTI could be affected by discordant therapy annually.

Children treated with discordant antibiotic therapy had a significantly longer LOS compared to those treated with concordant therapy. However, differences in time to fever resolution between the groups were not statistically significant. While resolution of fever may suggest clinical improvement and adequate empiric therapy, the lack of association with antibiotic concordance was not unexpected, since the relationship between fever resolution, clinical improvement, and LOS is complex and thus challenging to measure.21 These results support the notion that fever resolution alone may not be an adequate measure of clinical response.

It is possible that variability in discharge decision‐making may contribute to increased length of stay. Some clinicians may delay a patient's discharge until complete resolution of symptoms or knowledge of susceptibilities, while others may discharge patients that are still febrile and/or still receiving empiric antibiotics. Evidence‐based guidelines that address the appropriate time to discharge a patient with UTI are lacking. The American Academy of Pediatrics provides recommendations for use of parenteral antibiotics and hospital admission for patients with UTI, but does not address discharge decision‐making or patient management in the setting of discordant antibiotic therapy.2, 21

This study must be interpreted in the context of several limitations. First, our primary and secondary outcomes, LOS and fever duration, were surrogate measures for clinical response. We were not able to measure all clinical factors that may contribute to LOS, such as the patient's ability to tolerate oral fluids and antibiotics. Also, there may have been too few patients to detect a clinically important difference in fever duration between the concordant and discordant groups, especially for individual organisms. Although we did find a significant difference in LOS between patients treated with concordant compared with discordant therapy, there may be residual confounding from unobserved differences. This confounding, in conjunction with the small sample size, may cause us to underestimate the magnitude of the difference in LOS resulting from discordant therapy. Second, short‐term outcomes such as ICU admission were not investigated in this study; however, the proportion of patients admitted to the ICU in our population was quite small, precluding its use as a meaningful outcome measure. Third, the potential benefits to patients who were not exposed to unnecessary antibiotics, or harm to those that were exposed, could not be measured. Finally, our study was obtained using data from 5 free‐standing tertiary care pediatric facilities, thereby limiting its generalizability to other settings. Still, our rates of prophylactic antibiotic use, VUR, and GU abnormalities are similar to others reported in tertiary care children's hospitals, and we accounted for these covariates in our model.2225

As the frequency of infections caused by resistant bacteria increase, so will the number of patients receiving discordant antibiotics for UTI, compounding the challenge of empiric antimicrobial selection. Further research is needed to better understand how discordant initial antibiotic therapy contributes to LOS and whether it is associated with adverse short‐ and long‐term clinical outcomes. Such research could also aid in weighing the risk of broader‐spectrum prescribing on antimicrobial resistance patterns. While we identified an association between discordant initial antibiotic therapy and LOS, we were unable to determine the ideal empiric antibiotic therapy for patients hospitalized with UTI. Further investigation is needed to inform local and national practice guidelines for empiric antibiotic selection in patients with UTIs. This may also be an opportunity to decrease discordant empiric antibiotic selection, perhaps through use of antibiograms that stratify patients based on known factors, to lead to more specific initial therapy.

CONCLUSIONS

This study demonstrates that discordant antibiotic selection for UTI at admission is associated with longer hospital stay, but not fever duration. The full clinical consequences of discordant therapy, and the effects on length of stay, need to be better understood. Our findings, taken in combination with careful consideration of patient characteristics and prior history, may provide an opportunity to improve the hospital care for patients with UTIs.