Cefmetazole as an Alternative to Carbapenems Against Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Infections Based on In Vitro and In Vivo Pharmacokinetics/Pharmacodynamics Experiments

Comparative effectiveness of cefmetazole versus carbapenems and piperacillin/tazobactam as initial therapy for bacteremic acute cholangitis: A retrospective study

INTRODUCTION

Carbapenems and piperacillin/tazobactam (PIPC/TAZ) are commonly used as the initial therapy to treat extended-spectrum β-lactamase (ESBL)-producing Enterobacterales in acute cholangitis. However, the overuse of these antibiotics contributes to the spread of antimicrobial resistance. Cefmetazole (CMZ) is stable to hydrolysis by ESBLs, so it may be an alternative to carbapenems and PIPC/TAZ. However, the effectiveness of CMZ compared with that of carbapenems and PIPC/TAZ as the initial therapy for acute cholangitis is unknown.

METHODS

We conducted a retrospective cohort study at a university hospital between April 1, 2014, and December 31, 2022. Patients with bacteremic acute cholangitis who received CMZ, carbapenems, or PIPC/TAZ as the initial therapy were included. The patients were divided into a CMZ group and a carbapenems or PIPC/TAZ (CP) group to compare patient outcomes.

RESULTS

A total of 99 patients (54 in the CMZ group and 45 in the CP group) were analyzed. The baseline characteristics of the patients were similar and 30-day mortality did not differ between groups (4% vs. 7%, P = 0.66). However, the CMZ group had a shorter length of stay (LOS) (8 days vs. 15 days, P < 0.001) and lower mean antibiotic cost (98.92 USD vs. 269.49 USD, P < 0.001) than the CP group.

CONCLUSIONS

In bacteremic acute cholangitis, initial therapy with CMZ may contribute to a shorter LOS and lower antibiotic costs than treatment with carbapenems and PIPC/TAZ, without worsening patient outcomes.

Pharmacokinetics/pharmacodynamics analysis and establishment of optimal dosing regimens using unbound cefmetazole concentration for patients infected with Extended-Spectrum β-lactamase producing Enterobacterales (ESBL-E)

STUDY OBJECTIVE

Establish methods for measuring cefmetazole (CMZ) concentrations conduct a pharmacokinetic/pharmacodynamic (PK/PD) analysis using unbound CMZ concentrations for extended-spectrum β-lactamase producing enterobacterales (ESBL-E) and investigate optimal dosing regimens for not undergoing hemodialysis (non-HD) and undergoing hemodialysis (HD) patients.

DESIGN

Prospective observational study.

PATIENTS

Included patients treated with CMZ who provided written informed consent and were admitted to the Tokyo Bay Urayasu Ichikawa Medical Center between August 2021 and July 2022.

MEASUREMENTS

Total and Unbound CMZ concentration was measured by high-performance liquid chromatography (HPLC) with solid-phase extraction and ultrafiltration.

SETTING

Determining the CMZ dosing regimen involved modified creatinine clearance (CLCR ) with measured body weight (BW) using the Cockcroft-Gault equation. For non-HD patients, blood samples were collected during at least three points. For patients undergoing HD, 1 g was administered via intravenous infusion, or rapid intravenous injection after HD, or 30 min before the end of HD. Blood samples were collected before HD (pre-HD), and 1 and 3 h after starting HD and post-HD. All blood samples were collected at steady-state. Patient information was collected from electronic medical records. An unbound PK model was constructed for the non-HD patients. A nomogram was constructed using Monte Carlo simulations with a 90% probability of target attainment at 70% free time above the minimum inhibitory concentration (MIC). For the HD patients, a nomogram was used to determine the optimal dosing regimen for each HD schedule.

MAIN RESULTS

CMZ measurement methods were established. A model analysis of unbound PK in 37 non-HD patients incorporated creatinine clearance (CLCR ) using the Cockcroft-Gault equation, albumin (ALB) for clearance and body weight (BW) for the volume of distribution. In Monte Carlo simulations, nomograms corresponding to the MIC (known and unknown) were generated for each covariate. Using the nomogram, non-HD patients with an ESBL-E MIC of 8 mg/L, a BW of 60 kg, an ALB of 25 g/L, and a CLCR of 60 mL/min required administration of 2 g every 6 h (1- and 3-h infusions). Unbound PK model parameters were calculated for 7 HD patients, and the optimal dosing regimens following PK/PD were determined for each HD schedule. In HD patients, the regimen after and during HD was established using a treatment that was effective up to an ESBL-E MIC of 4 mg/L.

CONCLUSIONS

The nomogram for CMZ regimens established by PK/PD analysis of measured CMZ concentrations enables optimal CMZ dosing for ESBL-E-infected patients.

Effect of Different Approaches to Antimicrobial Therapy with Cefmetazole and Meropenem on the Time to Defervescence in Non-Severe Extended-Spectrum β-Lactamase-Producing Escherichia coli Bacteremia

Carbapenems are antimicrobial agents commonly used to treat extended-spectrum β-lactamase (ESBL)-producing bacteria. Although cefmetazole (CMZ) is considered effective for ESBL-producing Escherichia coli (ESBL-EC) bacteremia, previous studies showed its limitations, including the influence of the initial antimicrobial agent. Here, we examined the effects of different approaches to antimicrobial therapy with CMZ and meropenem (MEPM) on the time to defervescence in ESBL-EC bacteremia. Notably, the influence of previous antimicrobial agents was excluded. Inpatients with ESBL-EC detected in blood cultures between April 2018 and March 2023 were included and assigned to CMZ (n = 14), MEPM (n = 8), de-escalation to CMZ (dCMZ; n = 9), or escalation to MEPM (eMEPM; n = 11) groups. The median time to defervescence was 3.5, 1.0, 2.0, and 4.0 days in the CMZ, MEPM, dCMZ, and eMEPM groups, respectively, with no significant differences. Cox proportional hazards analysis showed a significant difference in the hazard ratio (95% confidence interval) of 0.378 (0.145-0.984) for the time to defervescence with CMZ versus MEPM (p = 0.046). The extent of a delayed time to defervescence is greater with early CMZ administration than with MEPM administration in patients with non-severe ESBL-EC bacteremia.

In vivo Pharmacokinetic/Pharmacodynamic Analysis of the Efficacy of the Cefepime/Nacubactam Combination Against β-Lactamase-Producing Enterobacterales based on the Instantaneous MIC Concept

PURPOSE

Nacubactam (NAC) is a novel diazabicyclooctane β-lactamase inhibitor used in combination with cefepime (CFPM). In this study, we aimed to determine the target pharmacokinetics (PK) and pharmacodynamics (PD) values of CFPM/NAC in mice infected with β-lactamase-producing Enterobacterales, such as the carbapenemase-producing Enterobacterales.

METHODS

Three strains of β-lactamase-producing Enterobacterales, Klebsiella pneumoniae MSC 21444, Escherichia coli MSC 20662, and K. pneumoniae ATCC BAA-1898, were used for checkerboard assays and fractionation studies and dose-range studies. A PK study was performed in neutropenic mice. Additionally, PK/PD analysis was performed based on the instantaneous minimum inhibitory concentration (MICi) concept.

RESULTS

Checkerboard measurements revealed that higher NAC concentrations decreased the CFPM MIC in a concentration-dependent manner. In all tested strains, fT > MICi calculated from the PK experiments showed a high correlation with the mean change in the bacterial count of thigh-infected mice in the in vivo PD study, suggesting that fT > MICi is an optimal PK/PD parameter for monitoring the CFPM/NAC combination. The target fT > MICi values for CFPM/NAC to achieve a bacteriostatic effect, 1-log10-kill, and 2-log10-kill values were 30, 49, and 94%, respectively.

CONCLUSIONS

Our results indicate that fT > MICi is a PK/PD parameter is suitable for monitoring the CFPM/NAC combination. The minimum target value for achieving a static effect against β-lactamase-producing Enterobacterales is 30%.

Prevalence, antibiotic resistance, and virulence gene profile of Escherichia coli strains shared between food and other sources in Africa: A systematic review

Background and Aim

Foodborne diseases caused by Escherichia coli are prevalent globally. Treatment is challenging due to antibiotic resistance in bacteria, except for foodborne infections due to Shiga toxin-producing E. coli, for which treatment is symptomatic. Several studies have been conducted in Africa on antibiotic resistance of E. coli isolated from several sources. The prevalence and distribution of resistant pathogenic E. coli isolated from food, human, and animal sources and environmental samples and their virulence gene profiles were systematically reviewed.

Materials and Methods

Bibliographic searches were performed using four databases. Research articles published between 2000 and 2022 on antibiotic susceptibility and virulence gene profile of E. coli isolated from food and other sources were selected.

Results

In total, 64 articles were selected from 14 African countries: 45% of the studies were conducted on food, 34% on animal samples, 21% on human disease surveillance, and 13% on environmental samples. According to these studies, E. coli is resistant to ~50 antimicrobial agents, multidrug-resistant, and can transmit at least 37 types of virulence genes. Polymerase chain reaction was used to characterize E. coli and determine virulence genes.

Conclusion

A significant variation in epidemiological data was noticed within countries, authors, and sources (settings). These results can be used as an updated database for monitoring E. coli resistance in Africa. More studies using state-of-the-art equipment are needed to determine all resistance and virulence genes in pathogenic E. coli isolated in Africa.

Pharmacokinetic-pharmacodynamic analysis of cefmetazole against extended-spectrum β-lactamase-producing Enterobacteriaceae in dogs using Monte Carlo Simulation

Introduction

The spread of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) is a serious concern in companion animal medicine owing to their ability to develop multidrug resistance. Cefmetazole (CMZ) is a candidate drug for treating ESBL-E infections; however, its regimen in dogs has not been established. In this study, we investigated the pharmacokinetic (PK) indices of CMZ in dogs and performed PK-pharmacodynamic (PD) analyses using Monte Carlo Simulation (MCS).

Methods

In total, six healthy dogs received an intravenous bolus dose of CMZ (40 mg/kg body weight). Serum CMZ concentrations were evaluated using liquid chromatography-mass spectrometry, and PK indices were determined based on non-compartmental analysis. The PK-PD cut-off (COPD) values were calculated as the highest minimum inhibitory concentration (MIC) that achieved ≥90% probability of target attainment for a target value of unbounded drug concentration exceeding 40% of the dosing interval. The cumulative fraction of response (CFR) was calculated based on the MIC distribution of wild-type ESBL-E from companion animals.

Results

The area under the concentration-time curve and elimination half-time were 103.36 ± 7.49 mg·h/L and 0.84 ± 0.07 h, respectively. MCS analysis revealed that COPD values for regimens of 40 mg/kg q12, q8h, and q6h were ≤ 0.5, ≤2, and ≤ 4 μg/mL, respectively. A regimen of 40 mg/kg q6h was estimated to achieve a CFR of 80-90% for Escherichia coli and Klebsiella pneumoniae. By contrast, all regimens exhibited a CFR of ≤70% for Proteus mirabilis and Enterobacter cloacae.

Discussion

We conclude that CMZ at 40 mg/kg q6h could be a viable treatment regimen for dogs infected with ESBL-producing Escherichia coli and Klebsiella pneumoniae.

Antimicrobial Efficacy Evaluations of Metronidazole against Clostridioides difficile Infection using Fecal Pharmacokinetic and Pharmacodynamic Analyses

OBJECTIVES

The pharmacokinetics/pharmacodynamics (PK/PD) characteristics of metronidazole (MNZ) in Clostridioides difficile infection (CDI) remain unclear. We aimed to determine the PK/PD characteristics of MNZ using a fecal PK/PD analysis model.

METHODS

Susceptibility testing, time-kill studies, and post-antibiotic effect (PAE) measurements were performed to evaluate in vitro PD profiles. MNZ was subcutaneously administered to mice infected with C. difficile ATCC® 43255 to evaluate in vivo PK and PD profiles, followed by determining fecal PK/PD indices with target value.

RESULTS

MNZ exerted concentration-dependent bactericidal activities with minimum inhibitory concentration (MIC) and PAE being 0.79 µg/mL and 4.8 h, respectively, against C. difficile ATCC® 43255. The reduction in vegetative cells in feces and treatment outcomes were most closely correlated with the ratio of the area under the fecal drug concentration-time curve from 0 to 24 h to the MIC (fecal AUC24/MIC). The target value of fecal AUC24/MIC to achieve a 1 log10 reduction in vegetative cells was 188. Upon meeting the target value, high survival rates (94.5%) and low clinical sickness score grading (5.2) were achieved in the CDI mouse models.

CONCLUSIONS

The PK/PD index and its target value of MNZ for CDI treatment was fecal AUC24/MIC ≥ 188. These findings may contribute to the effective clinical use of MNZ.

In vivo Pharmacokinetics/Pharmacodynamics Profiles for Appropriate Doses of Cefditoren pivoxil against S. pneumoniae in Murine Lung-Infection Model

PURPOSE

Cefditoren, the active form of cefditoren pivoxil, is an oral cephalosporin antimicrobial drug. Although cefditoren exhibits high antimicrobial activity against Streptococcus pneumoniae, its pharmacokinetics/pharmacodynamics (PK/PD) characteristics remain unknown. This study aimed to determine its PK/PD parameter with target values for cefditoren against S. pneumoniae in S. pneumoniae lung-infected mice and to simulate MIC range of S. pneumoniae that can be expected to be treated at approved cefditoren doses in human using population pharmacokinetic (PPK) data from patients.

METHODS

Susceptibility testing and time-kill assays against S. pneumoniae ATCC® 49619 were performed for in vitro PD evaluation. Based on the results of a PK study in healthy mice and PD studies in S. pneumoniae lung-infected mice, optimal PK/PD parameters were determined using the correlation curve between the PK/PD parameters and lung bacterial count changes. The target value was calculated to achieve a 2 log10 reduction in the lung bacterial counts.

RESULTS

In vitro PD evaluation showed that cefditoren had a potent antimicrobial effect against S. pneumoniae in a time-dependent manner at concentrations above the MIC. In PK/PD analyses, both fAUC24/MIC and fCmax/MIC were well correlated with bactericidal efficacy, achieving 2 log10-kill with fAUC24/MIC ≥ 63 and fCmax/MIC ≥ 16.

CONCLUSIONS

Cefditoren pivoxil has good therapeutic efficacy against acute pneumonia caused by S. pneumoniae with a MIC ≤ 0.031-0.063 mg/L at approved doses in adults and children.

Pharmacokinetics of cefmetazole in plasma, peritoneal fluid, peritoneum, and subcutaneous adipose tissue of patients scheduled for lower gastrointestinal surgery: Dosing considerations based on site-specific pharmacodynamic target attainment

INTRODUCTION

Cefmetazole (CMZ) has gained interest as a carbapenem-sparing alternative to the epidemic of extended-spectrum β-lactamase (ESBL)-producing Enterobacterales (ESBL-E). In this study, we investigated the pharmacokinetics (PK) of CMZ in plasma, peritoneal fluid, peritoneum, and subcutaneous adipose tissue to assess the dosing regimen needed to achieve pharmacodynamic (PD) goals at the target site.

METHODS

Patients scheduled for elective lower gastrointestinal surgery were intravenously administered CMZ. Plasma, peritoneal fluid, peritoneum, and subcutaneous adipose tissue samples were collected after CMZ infusion and during the surgery, and CMZ concentrations were measured. The non-compartmental and compartmental PK parameters were estimated and used to evaluate site-specific PD target attainment.

RESULTS

A total of 38 plasma, 27 peritoneal fluid, 36 peritoneum, and 38 subcutaneous adipose tissue samples were collected from 10 patients. The non-compartmental PK analysis revealed the ratios of the mean area under the drug concentration-time curve (AUC_0-3.5 h) of peritoneal fluid-to-plasma, peritoneum-to-plasma, and subcutaneous adipose tissue-to-plasma were 0.60, 0.36, and 0.11, respectively. The site-specific PD target attainment analyses based on the breakpoints for ESBL-E per the Japanese surgical site infection (SSI) surveillance (MIC₉₀ = 8 mg/L) revealed that 2 g CMZ every 3.5 h achieved desired bactericidal effect at all sites and 2 g CMZ every 6 h achieved PD goals at peritoneum and peritoneal fluid.

CONCLUSION

These findings clarify the PK of CMZ in abdominal tissues and could help decide optimal dosing regimens to treat intra-abdominal infection and prophylaxis of SSI.

Differences in Pharmacokinetic/Pharmacodynamic Parameters of Tedizolid Against VRE and MRSA

PURPOSE

Vancomycin-resistant enterococci (VRE) have recently become a major cause of nosocomial infections and a global public health concern. Tedizolid exhibits powerful antibacterial activity against VRE in vitro, but its pharmacokinetic/pharmacodynamic (PK/PD) parameters remain unclear. Therefore, we aimed to determine the PK/PD indices of tedizolid action on VRE and the mechanisms underlying the PK/PD indices differences of tedizolid against VRE and methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

Optimal PK/PD target values of tedizolid were determined in vitro, based on time-kill curves and post-antibiotic effects (PAEs), and in vivo, using mouse models of thigh infection with VRE and MRSA strains.

RESULTS

The tedizolid bactericidal activity on VRE and MRSA was time-dependent. Correlations were closest between fAUC₂₄/MIC and the tedizolid PK/PD index against MRSA and VRE. To achieve 1 log₁₀ kill tedizolid fAUC₂₄/MIC in neutropenic mouse models of thigh infection with VRE and MRSA should be 14.2 and 138.5, respectively. The PAEs of tedizolid against VRE and MRSA were 2.39 and 0.99 h, respectively.

CONCLUSION

Tedizolid showed bactericidal effects against VRE even in neutropenic mice unlike MRSA, which could be attributed to its longer PAE against VRE. Hence, we hypothesize that tedizolid treatment against VRE infections is promising for achieving therapeutic success in clinical.

Fecal pharmacokinetics/pharmacodynamics characteristics of fidaxomicin and vancomycin against Clostridioides difficile infection elucidated by in vivo feces-based infectious evaluation models

OBJECTIVES

The pharmacokinetics (PK)/pharmacodynamics (PD; PK/PD) characteristics of fidaxomicin (FDX) and vancomycin (VCM) against Clostridioides difficile infection (CDI) are yet to be elucidated because of the lack of an established PK/PD analysis method for intestinal infections and unabsorbed oral drugs. Here, we developed a feces-based PK/PD analysis method and determined the fecal PK/PD index, with target values of FDX and VCM against CDI.

METHODS

The antimicrobial susceptibility, time-kill curves, and post-antibiotic effects (PAEs) of FDX and VCM against C. difficile were determined in vitro. The optimal fecal PK/PD indices, with target values, were determined from the results of PK and PD studies involving 5-week-old female C57BL/6J mice infected with C. difficile ATCC® 43255. The minimum inhibitory concentration (MIC) breakpoints for C. difficile were estimated based on clinical data concerning fecal antibiotic concentrations in patients with CDI.

RESULTS

FDX and VCM inhibited C. difficile growth via time-dependent antibacterial activity and exerted PAEs. In the CDI mouse model experiments, the changes in C. difficile load and clinical cures (72-hour survival rates and clinical sickness score grading) were most highly correlated with the ratio of area under the fecal drug concentration-time curve to MIC (AUC_0→∞/MIC). The target AUC_0→∞/MIC values of FDX and VCM for 3 log₁₀ reduction in C. difficile load was 13,173 and 8,308, respectively. The MIC breakpoints of FDX and VCM for C. difficile was estimated to be 1.0 and 2.0 μg/mL, respectively.

CONCLUSIONS

The developed in vivo feces-based PK/PD analysis method elucidated the optimal fecal PK/PD index, with target values of FDX and VCM against CDI.

Concentration-Dependent Activity of Pazufloxacin against Pseudomonas aeruginosa: An In Vivo Pharmacokinetic/Pharmacodynamic Study

The bacterium Pseudomonas aeruginosa is known to be associated with nosocomial infections around the world. Pazufloxacin, a potent DNA gyrase inhibitor, is known to be an effective drug candidate. However, it has not been clarified whether the pharmacokinetic (PK)/pharmacodynamic (PD) of pazufloxacin was effective against P. aeruginosa. Herein, we demonstrated that the PK/PD index of pazufloxacin against P. aeruginosa infection is used to optimize the dosing regiments. We constructed an in vivo infection model by infecting P. aeruginosa into the thigh of a mouse to determine the PD, and we measured the serum concentration of pazufloxacin to construct the PK model using high-performance liquid chromatography. The therapeutic efficacy of pazufloxacin was correlated with the ratio of the area under the free concentration time curve at 24 h to the minimum inhibitory concentration (fAUC24/MIC), and the maximum free concentration to the MIC (fCmax/MIC). Each contribution rate (R2) was 0.72 and 0.65, respectively, whereas the time at which the free drug concentration remained above the MIC (R2 = 0.28). The target value of pazufloxacin fAUC24/MIC for stasis was 46.1, for 1 log10 it was 63.8, and for 2 log10 it was 100.8. Moreover, fCmax/MIC for stasis was 5.5, for 1 log10 it was 7.1, and for 2 log10 it was 10.8. We demonstrated that the in vivo concentration-dependent activity of pazufloxacin was effective against the P. aeruginosa infection, and successfully made the PK/PD model sufficiently bactericidal. The PK/PD model will be beneficial in preventing the spread of nosocomial infections.

Extended-spectrum-beta-lactamases and carbapenemase-producing Klebsiella pneumoniae isolated from fresh produce farms in different governorates of Egypt

Background and Aim: Fresh produce farms represents a major source of concern since they are becoming increasingly antibiotic resistant. This study aimed to investigate t he occurrence of carbapenemase and extended-spectrum-beta-lactamases (ESBL) - producing genes in Klebsiella pneumoniae isolated from fresh produce farms in Egypt, irrigation water, and people working in these fields. Materials and Methods: One hundred tomatoes from typical farms were collected in plastic bags. The study also included 20 surface-water samples from different irrigation watersheds in fresh produce farms, as well as 50 feces samples from farmworkers. Suspected K. pneumoniae was grown on Eosin Methylene Blue agar for 24 h before being biochemically identified using the RapID ONE test. PCR was used to detect carbapenemase (blaKPC, blaOXA-48, and blaNDM) and ESBL (blaSHV, blaTEM, and blaCTX) expressing genes on isolates. Results: K. pneumoniae was identified in 30% of water and 10% of worker samples, while only one isolate was found in tomato samples. One of the six irrigation water isolates tested positive for carbapenem-resistant NDM. In contrast, two isolates tested positive for ESBL determinants, one of which was blaSHV and the other having both blaSHV and blaTEM genes. Two of the five K. pneumoniae isolates from farmworkers were positive for blaNDM, with one isolate also testing positive for blaSHV and blaTEM. The blaOXA-48 gene was also discovered in the carbapenem-resistant K. pneumoniae tomato isolate used in this study. Conclusion: Carbapenemase- and ESBL-producing K. pneumoniae were found in fresh produce farms, implying that these resistance genes were being passed down to Egyptian consumers.