A randomized, controlled trial of prulifloxacin as conversion therapy after intravenous carbapenem in the treatment of acute pyelonephritis caused by third generation cephalosporin resistant pathogens: A pilot study

Abstract The efficacy of converting to oral fluoroquinolones after initial intravenous antibiotics for the treatment of acute pyelonephritis (APN) caused by the third‐generation cephalosporin resistant Enterobacteriaceae (3‐GCrEC) needs to be investigated. The objective was to compare the clinical and bacteriological outcome of oral prulifloxacin with intravenous ertapenem for the treatment of APN caused by 3‐GCrEC. A pilot, randomized controlled trial of patients with APN caused by 3‐GCrEC was conducted at two hospitals from August 2015 to December 2020. Any intravenous antimicrobial drug was initially permitted for empirical therapy. On day 4, adult patients (aged >18 years) with either non‐bacteremic or bacteremic APN were eligible for the study if their infection was caused by 3‐GCrEC susceptible to the study drugs. The patients were randomly assigned to receive either oral prulifloxacin or intravenous ertapenem. The total duration of antimicrobial therapy was 14 days. Of the 21 enrolled patients, 11 were treated with prulifloxacin, and 10 were treated with ertapenem. At the test of cure visit, there was no statistically significant difference between the patients with overall clinical success who were treated with prulifloxacin (90.9%) and those treated with ertapenem (100%, p = 0.999). In addition, there was no statistically significant difference in microbiological eradication between the prulifloxacin and ertapenem groups (100% vs. 100%, p = 0.999). The converting to oral prulifloxacin after intravenous antibiotics therapy appears to be an alternative option for treatment of APN caused by 3‐GCrEC. A further large randomized controlled trial should be investigated.


INTRODUCTION
][4] Intravenous ertapenem is the drug of choice for the treatment of patients with acute pyelonephritis (APN) caused by 3-GCrEC. 5Ertapenem, which is a beta-lactam antibiotics, inhibits the cell wall synthesis of bacteria. 6he overutilization of carbapenems has been associated with an increasing incidence of carbapenem-resistant Enterobacteriaceae. 7One of the recommended strategies by the guideline to reduce the overuse of intravenous carbapenems is to convert from intravenous to oral antimicrobial therapy. 8This change could help reduce the incidence of antibiotic resistance.This strategy involves initially treating patients with intravenous antibiotics for the first 2-3 days until they are clinically stable, and then transitioning them to oral medication. 8,9The advantages of antibiotic conversion therapy included reducing the length of hospital stays, decreasing the duration of intravenous therapy, and lowering the cost of medical care. 8,9][12] Fluoroquinolones might be used as a carbapenem-sparing therapy for infections caused by 3-GCrEC, if there is susceptibility to fluoroquinolones from in vitro antibiotic susceptibility tests.Prulifloxacin, which is a fluoroquinolone, interferes with DNA synthesis by inhibiting topoisomerases II and IV. 13 Prulifloxacin is bactericidal and has a broad spectrum of activity against bacteria of the order Enterobacterales. 13The previous studies reported the in vitro activity of prulifloxacin was generally greater than that of ciprofloxacin and other fluoroquinolones against isolates of Gram-negative bacteria, including E. coli, Klebsiella spp. 14,15In addition, some bacterial isolates were resistant to ciprofloxacin but susceptible to prulifloxacin. 14The exact mechanism by which prulifloxacin can overcome resistance to other fluoroquinolones is not yet understood.It could be explained by prulifloxacin was not the substrate of the AcrAB-TolC efflux pump. 16After oral administration, prulifloxacin is rapidly and extensively converted into its active metabolite, ulifloxacin. 17The proportion of prulifloxacin's peak urinary concentration to the minimum inhibitory concentration breakpoint (2 μg/mL) is more than 10 times higher. 17,18The duration during which prulifloxacin's urinary concentration remains more

WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?
Carbapenems are the drug of choice for treatment of patients with acute pyelonephritis (APN) caused by third-generation cephalosporin-resistant Enterobacteriaceae (3-GCrEC).However, there are little data regarding the clinical efficacy of oral prulifloxacin for the conversion after intravenous antibiotic for treatment of APN caused by 3-GCrEC.

WHAT QUESTION DID THIS STUDY ADDRESS?
Can oral prulifloxacin be used for the conversion after intravenous antibiotic for treatment of patients with APN caused by 3-GCrEC?

WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?
Prulifloxacin demonstrated a high overall clinical success and a high microbiological eradication.Because of the limited statistical power of the study, these results cannot be interpreted that converting to oral prulifloxacin after intravenous antibiotic is as effective as intravenous ertapenem.

HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?
The converting to oral prulifloxacin after intravenous antibiotics appears to be an alternative drug for treatment of APN caused by 3-GCrEC.A further large randomized controlled trial should be investigated.than five times above the minimum inhibitory concentration (MIC) breakpoint (2 μg/mL) is 24 h. 17This value can be used to predict the efficacy of prulifloxacin for definitive treatment in patients with urinary tract infections. 18In addition, prulifloxacin has been reported to be efficacious for the treatment of patients with urinary tract infections. 13Furthermore, studies from Thailand have shown that prulifloxacin is active against some isolations of 3-GCrEC. 19,20Thus, converting to oral prulifloxacin after intravenous antibiotic has the potential to be used for treatment of APN caused by 3-GCrEC.However, there are little data regarding the clinical efficacy of fluoroquinolones for the definitive treatment of APN caused by 3-GCrEC.The aim of this study was to compare the clinical and microbiological outcome of two groups of patients, patients treated with ertapenem versus patients treated with prulifloxacin, for the definitive treatment of APN caused by 3-GCrEC.

Study design
This prospective, open-label, randomized controlled trial was conducted at two hospitals in Bangkok, Thailand, Taksin hospital, and Bhumirajanagarindra Kidney Institute Hospital, from August 2015 to December 2020.Written consent was obtained from all patients.The protocol was approved by the Institutional Review Board, Faculty of Dentistry and Faculty of Pharmacy, Mahidol University, Thailand, with reference number 2015/017.0105,and the Bangkok Metropolitan Administration Human Research Ethics Committee, with reference number U024h/58.This study was registered at the Thai Clinical Trials Registry, with the reference number TCTR20181202002.Eligible patients were stratified according to the diagnosis of APN, with or without bacteremia.On day 4, when the results of urine culture and blood culture were reported, patients were enrolled and randomized 1:1 to receive intravenous ertapenem or oral prulifloxacin.Randomization was performed using a computer-generated random number allocation schedule with a block of four.

Study population
Adult patients (aged >18 years) with either non-bacteremic APN or bacteremic APN were eligible for the study if the infection was caused by 3-GCrEC susceptible to the study drugs.Additional inclusion criteria were that patients (1) required intravenous antimicrobial therapy; and (2) did not have clinical worsening after the initiation of empirical antimicrobial therapy.Patients with fever (body temperature ≥37.8°C, or <36°C) were diagnosed with APN if they had signs and symptoms compatible with the criteria and no other recognized cause.The criteria for APN were pyuria (≥10 white blood cells per high power field), urinary syndrome (dysuria, urgency, or urinary frequency), flank pain, costovertebral angle tenderness, and a positive urine culture of 10 4 colonyforming units/mL.Exclusion criteria were pregnancy or lactation in women, a history of allergy to fluoroquinolones or beta-lactams, treatment with antiretroviral drugs or systemic immunosuppressive drugs, including corticosteroids, the need for concomitant antimicrobial drugs in addition to the study therapy, the need of surgery for urinary tract obstruction, serious diseases leading to a shortened lifespan of no more than 72 h, neutropenia (absolute neutrophil counts ≤500 cells/μL), and a creatinine clearance (CrCl) of less than 20 mL/min.

Study intervention
The flow of antimicrobial treatment, clinical, and microbiological assessments is shown in Figure 1.All patients, whether they had non-bacteremic or bacteremic APN, initially received any intravenous antimicrobial drugs for the first 3 days of treatment.On day 4, all patients were randomized to receive either intravenous ertapenem or oral prulifloxacin.All patients without bacteremia were prescribed intravenous ertapenem on day 4. Patients without bacteremia were monitored between day 4 and day 7 for criteria that would allow them to transition from intravenous to oral therapy.If the patients met these criteria on any day within this timeframe, they were assigned to receive the study drugs as soon as possible.However, if the criteria were met on day 4, they received the study drugs immediately.Eligible patients with bacteremic APN were prescribed intravenous ertapenem between day 4 and day 7.The patients with bacteremic APN who met the criteria for conversion from intravenous to oral therapy on day 8 were assigned to receive the study drugs.All patients, both non-bacteremic and bacteremic, were monitored until day 8 for criteria for conversion from intravenous to oral therapy.If all patients did not meet the criteria on day 8, they were excluded from the study.
After the assignment of study drugs, patients could complete their therapy either in the hospital or at home.Outpatient parenteral antimicrobial therapy was also permitted.All patients had to be candidates for conversion from intravenous to oral therapy.The criteria for conversion from intravenous to oral therapy included all of the following: (1) afebrile (body temperature 36-37.7°C);(2)  hemodynamically stable; (3) improvement in signs, symptoms, and leukocytosis; (4) resolution of nausea and vomiting; and (5) ability to adequately absorb oral medications or food.For patients with bacteremic APN, an additional criterion for conversion was that the blood culture collected on day 4 reported no growth.The total duration of antimicrobial treatment for all patients was 14 days.The study drugs were renally adjusted according to CrCl, which was estimated for all patients using the Cockcroft-Gault formula.Carbapenem dosing was administered according to the Micromedex electronic databases. 21The dosage for patients with a CrCl greater than 40 mL/min receiving prulifloxacin was 400 mg orally once daily.For patients with a CrCl of 20-40 mL/min, the dosage was 200 mg orally once daily.Prulifloxacin was taken orally before a meal.

Clinical and microbiological assessment
On the day of enrollment, the laboratory evaluation included complete blood count (CBC), blood urea nitrogen (BUN), serum creatinine (Scr), electrolytes, and a urine pregnancy test for patients of child-bearing potential.
Additionally, a blood culture was also performed on the day of enrollment for patients with bacteremic APN.The clinical response was assessed at the time of transitioning to oral medication (on any day between day 4 and 7), on any day between day 15 and 21 (test of cure [TOC] visit), and on any day between day 29 and 42 (late follow-up [LFC] visit), with the laboratory evaluation including: CBC, urinalysis (UA), and urine culture (UC) at the time of transitioning to oral medication; CBC, BUN, Scr, electrolytes, UA, and UC at the TOC visit; and CBC, UA, and UC at the LFC visit.The symptom and compliance to oral prulifloxacin assessments were performed over the entire study period by interviewing the patients at the hospital, or via the telephone in cases where patients were discharged.Any adverse events were evaluated by a physician.
Pathogens isolated from urine and blood specimens were identified at the microbiology laboratory of the study hospital.All isolates were tested for in vitro susceptibility according to the guidelines of the Clinical Laboratory Standard Institute (CLSI). 22In vitro susceptibility testing of all isolates was performed using the disk diffusion methods.The CLSI has not published an in vitro susceptibility test for prulifloxacin, and in vitro susceptibility to The flow of antimicrobial treatment, clinical and microbiological assessments.ATB, antibiotic; BUN, blood urea nitrogen; CBC, complete blood count; H/C, hemoculture; IV, intravenous; LFC, Late follow up; Scr, serum creatinine; TOC, test of cure; UA, urinalysis; UC, urine culture; UPT, urine pregnancy test.this agent was therefore determined by a disk diffusion method.The zone diameter breakpoint for prulifloxacin-susceptible isolates was greater than or equal to 16 mm (MIC ≤2 μg/mL). 19The manufacturer of the disks with prulifloxacin was the Eiken chemical Co., Ltd.

outcomes
At the TOC visit, the clinical response was assessed as overall clinical success, failure, or indeterminate.Overall clinical success included a cure and a clinical improvement, where a cure was defined as the resolution of all pretreatment signs and symptoms, whereas clinical improvement was defined as the persistence of a few pretreatment signs and symptoms, but no fever (body temperature 36-37.7°C).Failure was defined as having a fever (body temperature ≥37.8°C, or <36°C) and the persistence or progression of most pretreatment signs and symptoms.Indeterminate was applicable to patients lost for follow-up or who had died from other causes.The primary clinical outcome was overall clinical success at the TOC visit, and the secondary clinical outcome was recurrent infection at the LFC visit.Recurrent infection was defined as the new onset of signs and symptoms of APN after the TOC visit or at the LFC visit.Bacteriological outcomes were assessed as eradication, super bacterial infection, and indeterminate, using a quantitative urine culture at the TOC visit and the LFC visit.Eradication of the original uropathogen was defined as the urine containing less than 10 4 CFU/mL.Super bacterial infection was defined when greater than or equal to 10 4 CFU/mL of an uropathogen that was different from baseline pathogen grew during therapy.Additionally, in cases where the same pathogen grew at the TOC and LFC visits, super bacterial infection was assigned if the pathogen demonstrated increased resistance, or different antimicrobial susceptibility.Persistence was defined as the original uropathogen growing by greater than or equal to 10 4 CFU/mL.

Statistical analysis
Continuous variables are presented as the median and interquartile range and are compared in each group using the Mann-Whitney U test.Categorical variables are presented as percentages and are compared in each group using the Fisher's exact test or Pearson's chi-square test.The intention to treat principle was used for all analyses.All p values were two-tailed, and p values less than 0.05 were considered statistically significant.SPSS for Windows (version 23 software package; SPSS Inc.) was used for the analysis.

RESULTS
Of the 21 randomized patients, 11 were treated with prulifloxacin and 10 were treated with ertapenem (Figure 2).The patient characteristics are shown in Table 1.There were no statistically significant differences in baseline characteristics between patients treated with prulifloxacin and patients treated with ertapenem, except that the proportion of patients with diabetes mellitus was significantly higher in the group treated with prulifloxacin compared to the group treated with ertapenem (81.8% vs. 30%, p = 0.03).All patients treated with prulifloxacin had compliance rates of 100%.There were two causative uropathogens, E. coli and P. mirabilis, identified in one patient in the ertapenem group.The distribution of  group had indwelling urinary catheters.In the prulifloxacin group, the mean (SD) duration of intravenous therapy for patients without bacteremia was 4.3 (1.1) days, whereas for patients with bacteremia, it was 7 days.The clinical and bacteriological outcomes are shown in Table 3.The reasons for the missing data in patients at the TOC visit and LFC visit were explained in the Appendix S1.At the TOC visit, there was no statistically significant difference in overall clinical success between patients treated with prulifloxacin and patients treated with ertapenem (90.9% vs. 100%, p = 0.999), and there was also no statistically significant difference in microbiological eradication between patients in the two groups (100% vs. 100%, p = 0.999).Similarly, among super bacterial infection, no difference was noted between the prulifloxacin group and the ertapenem group (40% vs. 40%, p = 0.999).The detail about the pathogen responsible for the super bacterial infection is shown in the Table S1.
At the LFC visit, there was no statistically significant difference in recurrent infection between patients treated with prulifloxacin and those treated with ertapenem (0% vs. 10%, p = 0.999), and no difference in microbiological eradication was noted between the two groups (100% vs. 100%, p = 0.999).P. aeruginosa was a causative pathogen among patients with recurrent infection in the ertapenem group.Similarly, among super bacterial infection, no difference was noted between the prulifloxacin group and the ertapenem group (70% vs. 75%, p = 0.999).Between the TOC and LFC visits, patients in both groups did not receive antibiotics, except for two patients in the prulifloxacin group.One patient was classified as a treatment failure due to recurrent infection.Another patient was classified as clinical improvement.This patient had no fever and was subsequently diagnosed with cystitis.
Adverse events occurred in one patient in the prulifloxacin group; however, this adverse event did not relate to prulifloxacin.The patient developed congestive heart failure on day 9 of treatment, prulifloxacin was discontinued, and no additional antimicrobial drug was prescribed for treatment.The patient was cured, and no recurrent infection was observed.

DISCUSSION
Our results showed that there was no statistically significant difference in overall clinical success and microbiological eradication among patients treated with prulifloxacin and those treated with ertapenem: the overall clinical success was 90.9% of the patients treated with prulifloxacin  Note: The in vitro testing was performed using the disc diffusion method. 22Antibiotic resistance was defined as the inhibition zone diameter each drug to be compatible with resistant according to the Clinical Laboratory Standard Institute. 22The in vitro testing of cefoperazone/sulbactam was performed using inhibition zone diameter of cefoperazone according to the Clinical Laboratory Standard Institute. 22breviations: n, number of strains that demonstrated resistance in each group; N, total number of strains in each group.
T A B L E 2 Antibiotic resistance patterns of 22 pathogens.and 100% of those treated with ertapenem.The cause of treatment failure in one patient treated with prulifloxacin was that the patient could not void after undergoing orthopedic surgery; however, the urine culture (UC) of this patient at the time of failure indicated no growth.All patients in this study had a negative UC or recovered clinically before assignment to receive either intravenous ertapenem or oral prulifloxacin.4][25] The guidelines recommended that duration of treatment was 7-14 days for patients with uncomplicated acute pyelonephritis. 1,10In addition, the failure rates of microbiological cure and clinical cure were significantly higher among patients receiving antibiotics for 3 days than patients receiving antibiotics for 14 days. 26Therefore, definitive treatment, either with oral prulifloxacin or ertapenem, is an important consideration to achieve better outcomes.Similarly, the results of previous randomized controlled trials showed no difference in clinical cure rate between patients treated definitely with fluoroquinolones and patients treated with ertapenem for APN caused by ESBL producing E. coli. 23Furthermore, a retrospective study showed that the mortality rate was no different among patients treated empirically with fluoroquinolones and those treated empirically with carbapenems. 27The majority of patients treated with fluoroquinolones in this study and in previous studies had non-severe infections. 23,27With regard to patients with severe infection, there are reports that patients treated empirically with carbapenems had a better mortality outcome compared with those treated empirically with ciprofloxacin. 28,29Another situation that impacts on treatment success was the ability to achieve an adequate concentration of ciprofloxacin at the site of infection. 28,29This study enrolled patients whose infections were caused by a pathogen that is susceptible to prulifloxacin; after oral prulifloxacin administration, the drug concentrations in the urine are high enough to eradicate the pathogen. 17,18ur study found there were no statistically significant differences in recurrent infection and microbiological eradication between patients treated with prulifloxacin and those treated with ertapenem, which is concordant with the results of a previous randomized controlled trial. 23Our study found that the microbiological eradication rate in the two treatment groups was higher than There were two causative uropathogens identified in three patients in the prulifloxacin group.c There were two causative uropathogens identified in one patient in the ertapenem group.reported in the previous randomized controlled trial. 23This could be explained by the difference in the definition of microbiological eradication: the previous study defined microbiological eradication as no growth in UC, whereas our study defined it as greater than or equal to 10 4 CFU/mL of an original uropathogen at the time to diagnosis being reduced to less than 10 4 CFU/ mL. 23For super bacterial infection in the prulifloxacin group at the TOC visit, ESBL producing E. coli was detected in three patients, and E. faecium was detected in one patient; meanwhile, in the ertapenem group at the TOC visit, E. faecium was detected in three patients, and A. baumanii was detected in two patients.This might be because ertapenem was not active against those pathogens. 30None of the patients with super bacterial infection had any symptoms that were compatible with APN, and these positive UCs were classified as asymptomatic bacteriuria.
Our study is the first well-designed randomized trolled trial comparing the efficacy in two group: patients treated with ertapenem versus patients treated with prulifloxacin, for the definitive treatment of patients with non-bacteremic APN or patients with bacteremic APN caused by 3-GCrEC.Moreover, our study was designed to evaluate recurrent APN, 2-4 weeks after the end of treatment.However, only a small number of patients were included in this study.The explanation of this limitation of less sample size was incidence of increasing resistance rates in 3-GCrEC every year.In addition, the large number of hospital beds needed to be provided for patients with coronavirus disease 2019 (COVID-19) after the COVID-19 pandemic.
Prulifloxacin demonstrated a high overall clinical success, which was consistent with the results from previous randomized controlled trials. 23An oral prulifloxacin might be considered as an alternative drug for treatment of APN caused by 3-GCrEC.Conversion from intravenous to oral antibiotic therapy could decrease the length of hospital stay.Because of the limited statistical power of the study, these results cannot be interpreted that converting to oral prulifloxacin is as effective as intravenous ertapenem.A further large randomized controlled trial should be performed.In conclusion, converting to oral prulifloxacin after intravenous antibiotics seems to demonstrate a high success rate of clinical outcome, and microbiological outcome in comparison with intravenous ertapenem.

T A B L E 1
Baseline characteristics of enrolled patients.