Therapeutic drug monitoring of six contraindicated/co-administered drugs by simple and green RP-HPLC-PDA; application to spiked human plasma

Therapeutic drug monitoring is an important clinical testing of the drugs to monitor their concentrations in plasma in order to guarantee their optimal impact, and to avoid any side effects resulting from drug-drug interactions. A green reversed-phase high-performance liquid chromatographic method using a photodiode array detector (RP-HPLC-PDA) was developed for the simultaneous determination of three carbapenem antibiotics (Imipenem, ertapenem, and meropenem) with the co-formulated drug (cilastatin) and contraindicated drugs (probenecid and warfarin) in spiked human plasma. The separation was achieved at 25 °C using a gradient elution of a mixture of mobile phase A: methanol and mobile phase B: phosphate buffer (pH 3.0). The photodiode array detector was adjusted at 220 nm. Bioanalytical method validation was carried out as per the FDA guidelines, and the method showed good linearity ranges for the six drugs that included their Cmax levels along with low limits of quantification. Based on the results, the method was found to be accurate and precise; with high % recovery and good % RSD, respectively. The method was successfully applied to spiked human plasma, signifying a good potential to be implemented in future TDM studies of these drugs when co-administered together.

Antimicrobial activity of eravacycline and other comparative agents on aerobic and anaerobic bacterial pathogens in Taiwan: A clinical microbiological study

OBJECTIVES

Eravacycline, a new tetracycline derivative, exhibits broad-spectrum antimicrobial susceptibility. This study aimed to comprehensively investigate in vitro activities of eravacycline, tigecycline, and ertapenem against various Gram-positive, Gram-negative, and anaerobic bacteria.

METHODS

Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method. The following bacterial species were collected: vancomycin-sensitive (VS) Enterococci species, vancomycin-resistant Enterococci species (VRE), Staphylococcus aureus, Streptococcus anginosus, Bacteroides species, Clostridioides difficile, Clostridium innocuum, Clostridium perfringens, Parabacteroides distasonis, and Stenotrophomonas maltophilia.

RESULTS

We found that eravacycline exhibited superior in vitro activity compared to tigecycline and ertapenem. Notably, it exhibited the lowest MIC90 for several bacterial species, including VS E. faecalis (0.12 µg/mL), VS E. faecium (0.12 µg/mL), and others. Besides, VRE was susceptible to eravacycline (MIC90:0.12 µg/mL) and tigecycline (MIC90:0.12 µg/mL), but was all resistant to ertapenem (MIC90 > 64 µg/mL). S. aureus was also susceptible to eravacycline (MIC90:0.5 µg/mL) as well as tigecycline (MIC90:1.0 µg/mL). Furthermore, S. anginosus showed higher susceptibility to eravacycline (MIC90:2.0 µg/mL) and tigecycline (MIC90:4.0 µg/mL), but lower to ertapenem (MIC90:32.0 µg/mL). Eravacycline and tigecycline also demonstrated good susceptibility to anaerobes, including Bacteroides species (susceptibility rate: 100%), P. distasonis (100%), C. difficile (94.1‒100%), C. innocuum (94.1‒96.1%), and C. perfringens (88.9‒96.3%). For S. maltophilia, both tigecycline and eravacycline showed an MIC90 of 2 µg/mL. A moderate-to-strong correlation (rho = 0.608-0.804, P < 0.001) was noted between the MIC values of eravacycline and tigecycline against various bacterial species.

CONCLUSIONS

Our study highlights the potential of eravacycline as an effective treatment option for multidrug-resistant bacterial infections.

Acute Thrombocytosis in a Patient Treated with Ertapenem

Ertapenem, a carbapenem-type beta-lactam antibiotic, demonstrates broad-spectrum efficacy against a wide range of Gram-positive and Gram-negative bacteria, including aerobes and anaerobes. Importantly, it demonstrates resistance to virtually all beta-lactamases, including the extended spectrum beta-lactamases (ESBLs). Haematologic complications such as thrombocytosis, haemolysis, anaemia, and neutropenia are infrequent side effects associated with this drug. In this report, we present a rare case of ertapenem-induced thrombocytosis in a 62-year-old female patient who was admitted for a complicated urinary tract infection caused by Escherichia coli.

LEARNING POINTS

Ertapenem was identified as the most likely cause of thrombocytosis.Discontinuing ertapenem normalised the platelet count.It is crucial for physicians to identify and address causes of thrombocytosis, particularly when related to medications, to avoid inadvertent complications and to ensure effective patient care.

Ertapenem combined with metronidazole for treatment of complex abdominal infections: Efficacy and impact on serum inflammatory indicators and T lymphocyte subsets

BACKGROUND

Complex intra-abdominal infections (cIAIs), often associated with abdominal trauma, have a complex etiology, are acute and severe, and have a high risk. They are an important cause of death in patients with abdominal trauma. Safe and effective treatment strategies are the factors affecting the prognosis of such patients.

AIM

To investigate the efficacy and safey of ertapenem combined with metronidazole in the treatment of cIAIs as well as the impact on serum inflammatory markers and T lymphocyte subsets, recovery status, and treatment costs.

METHODS

A total of 92 patients with cIAIs treated at our hospital from June 2021 to January 2023 were randomly divided into a control group and a study group, with 46 cases in each group. After admission, both groups received puncture drainage, continuous double-cannula irrigation, anti-infection therapy, organ function support, nutritional support, and other treatments. On this basis, the control group was treated with piperacillin/tazobactam combined with metronidazole, while the study group was treated with ertapenem combined with metronidazole. The therapeutic effects, recovery conditions, treatment costs, serum inflammatory indicators [procalcitonin (PCT), Toll-like receptor 4 (TLR-4), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP)], T lymphocyte subsets (CD3⁺, CD4⁺, and CD4⁺/CD8⁺ ratio), acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score, sequential organ failure assessment (SOFA) score, adverse reactions, and bacterial culture results were compared between the two groups.

RESULTS

The total effective rate of the study group was 93.48%, significantly higher than that of the control group (78.26%; P < 0.05). After 3 d and 7 d of treatment, the levels of serum PCT, TLR-4, TNF-α, and CRP in the study group were significantly lower and the levels of serum CD3⁺ and CD4⁺ T lymphocytes and CD4⁺/CD8⁺ ratio were significantly higher than those of the control group (P < 0.05). The APACHEⅡ score and SOFA score of the study group were significantly lower than those of the control group after 3 d and 7 d of treatment (P < 0.05). The time to fever resolution, ICU stay duration, and hospital stay in the study group were significantly shorter than those of the control group, and the costs of drugs and other resources were less than those of the control group (P < 0.05). The incidence of adverse reactions in the study group was 4.35%, significantly lower than that of the control group (17.39%; P < 0.05). There was no significant difference in the distribution of pathogenic bacteria between the two groups before and after treatment (P > 0.05).

CONCLUSION

Ertapenem combined with metronidazole is effective in the treatment of cIAIs, which can reduce inflammation, improve immune function, control disease progression, reduce the risk of organ failure, reduce the economic burden of patients, and improve treatment safety.

Perianal abscess in children: an evaluation of microbiological etiology and the effectiveness of antibiotics

PURPOSE

We aimed to evaluate the demographic characteristics of children with perianal abscess, distribution of microbiological etiology, antibiotic susceptibility, and identify the effectiveness and coverage of antibiotics due to culture results.

METHODS

A retrospective study was designed to evaluate pediatric patients with perianal abscesses between January 2013 and December 2022.

RESULTS

A total of 197 episodes in 135 patients were evaluated. The median age of the patients was 10 months (22 days-17 years). The isolated microorganisms were Gram-positive bacteria in 56 (28.4%) patients and Gram-negative bacteria in 141 (71.6%) patients. The most common isolated species was Escherichia coli (n = 70, 35.5%), followed by Klebsiella spp. (n = 48, 24.4%), Staphylococcus aureus (n = 37, 18.9%), and Enterobacter spp. (n = 9, 4.5%). Forthy-two percent (n = 58) of isolates were positive for extended-spectrum beta-lactamase, 8% (n = 11) were carbapenem-resistant in Gram-negative bacteria, and 37.5% (n = 21) were methicillin-resistant, 7.1% (n = 4) were vancomycin-resistant in Gram-positive bacteria. According to bacterial culture results, ertapenem plus glycopeptide had the highest antimicrobial coverage rate (92.3%), followed by ertapenem plus clindamycin (89.8%), ertapenem (81.7%), third-generation cephalosporin plus glycopeptide (82.2%), third-generation cephalosporin plus clindamycin (69.5%).

CONCLUSION

Ertapenem can be a good choice in the empirical treatment of perianal abscesses in children due to its high coverage rate.

Proteomics profiling of ertapenem challenged major porin deficient carbapenem-resistant Klebsiella pneumoniae

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an urgent threat to human health. Major outer membrane proteins (OMPs) porin mutation is one important resistance mechanism of CRKP, and may also affect the inhibition activity of β-lactam and β-lactamase inhibitor combinations. The ertapenem-resistant K. pneumoniae strain 2018B120 with major porin mutations was isolated from a clinical patient. Genomic and time-series proteomic analyses were conducted to retrieve the ertapenem-challenged response of 2018B120. The abundance changing of proteins from PTS systems， ABC transporters, the autoinducer 2 (AI-2) quorum sensing system, and antioxidant systems can be observed. Overexpression of alternative porins was also noticed to balance major porins' defection. These findings added a detailed regulation network in bacterial resistance mechanisms and gave new insights into bypass adaptation mechanisms the porin deficient bacteria adopted under carbapenem antibiotics pressure. SIGNIFICANCE: Outer membrane porins deficiency is an important mechanism of carbapenem resistance in K. pneumoniae. Comprehensive genomic and proteomic profiling of an ertapenem-resistant K. pneumoniae strain 2018B120 gives a detailed systematic regulation network in bacterial resistance mechanisms. Overexpression of alternative porins to balance major porins' defection was noticed, giving new insights into bypass adaptation mechanisms of porin deficient bacteria.

Probable ertapenem-induced encephalopathy; case report and suggested alternatives for chronic prostatitis

Ertapenem is a carbapenem antibiotic usually reserved for complicated infections. Drug-induced neurotoxicity is a rare adverse reaction associated with ertapenem, and may be directly related to its chemical structure. We report a case of a 64-year-old male with a hematological history and chronic prostatitis that was admitted to hospital for gait instability, clumsiness, dysarthria and tremors. He started ertapenem intravenous 1 g once daily a week prior to admission. Creatinine clearance calculation by the Cockcroft-Gault method was 52 mL/min and total protein levels were low. Ertapenem's administration was discontinued and the patient's neurological symptoms improved dramatically just one day after. The result of the Naranjo Scale was six, suggesting a probable adverse drug reaction. We discussed if he could receive meropenem in case of severe infection such as septic shock. Considering the patient's medical history, the chemical structure of meropenem and the fact that there are almost no reported cases of neurotoxicity from this drug, we assume that meropenem could be used in case of severe infection in patients with history of neurotoxicity caused by ertapenem if no added risk factors are present, such as renal failure.

Utility of Silver-nanoparticles for Nano Spectrofluorimetric Determination of Meropenem and Ertapenem: Bio-analytical Validation

Bio-analytical, nano-quantitative spectrofluorimetric estimation of two non-classical β-lactam antibiotics; meropenem (MP) and ertapenem (EP) is presented. The method is based on the enhancement of the fluorescence intensity of MP-Eu³⁺/EP-Eu³⁺ with silver nanoparticles (AgNPs). AgNPs were synthesized and characterized by UV and transmission electron microscope (TEM). The plasmon resonance produced an intense absorption maximum at 398.0 nm. TEM micrograph showed the particle morphology with an average particles size of 13.0 ± 2.95 nm. The fluorescence intensities were measured against blank reagents at λem of 396.0 nm and 405.0 nm after excitation at λex 305.0 nm and 303.0 nm for MP and EP, respectively. Under optimum conditions, the relative fluorescence intensity showed a good linear relationship with the concentration ranges of 4.0-14.0 and 4.0 -12.0 ng/mL with excellent correlation coefficients of 0.9998 and 0.9997, and limit of detection of 0.84 and 0.86 ng/mL for MP and EP, respectively. The method was successfully applied for direct analysis of MP and EP in their drug substances and pharmaceutical vials. The significant, sensitivity and practicality of the method facilitated MP detection in real plasma samples. Bio-analytical validation was performed according to FDA. The method was rectilinear over the ranges of, 5.0 -75.0 μg/mL plasma. Interestingly, this described system has a promising benefit for various applications exploiting the dramatically enhanced-fluorescence occurrence.

An outbreak of ertapenem-resistant, carbapenemase-negative and porin-deficient ESBL-producing Klebsiella pneumoniae complex

Introduction

Carbapenem-resistant Klebsiella pneumoniae is an emerging healthcare-associated pathogen with dynamic molecular epidemiology. This study presents a retrospective analysis of the distribution and antibiotic resistance patterns of ertapenem-resistant ESBL-producing K. pneumoniae strains recovered during an outbreak from 2012 to 2014 in a Croatian University hospital.

Methods

We aimed to estimate genetic relatedness of clinical isolates and underlying mechanisms that conferred the ertapenem-resistant phenotype.

Results

Expression analysis of genes involved in the antibiotic resistance showed reduced expression of major non-selective porin channel OmpK35. Reduced expression of OmpK36 porin channel in isolates resistant to at least one more carbapenem, apart from the ertapenem, was found to a lesser degree. Pulsed-field gel electrophoresis analysis of genomic DNA revealed that almost all isolates belonged to the same genetic clone.

Conclusions

Caution regarding ertapenem-resistant, carbapenemase-negative porin-deficient mutants of K. pneumoniae is required as they are widespread, and under selective pressure this could result in a local clonal outbreak.

Campylobacter fetus aortitis in a patient with HIV

A 36-year-old man with well controlled HIV developed Campylobacter fetus aortitis. To prevent aortic rupture, emergent surgical resection and neo-aortoiliac replacement with his left femoral vein was conducted. After surgical intervention, he was successfully treated with intravenous ertapenem for 6 weeks followed by oral amoxicillin for 3 months.

Investigation of the presence of carbapenemases in carbapenem-resistant Klebsiella pneumoniae strains by MALDI-TOF MS (matrix-assisted laser desorption ionization-time of flight mass spectrometry) and comparison with real-time PCR method

PURPOSE

We aimed to develop a new procedure for rapid detection of the carbapenemase activity using MALDI-TOF MS, and to determine the sensitivity and specificity of the method. Also, we aimed to determine the distribution of carbapenemase genes among the K.pneumoniae strains isolated in our hospital using real-time PCR.

METHOD

Between January 2017-February 2019; K. pneumoniae strains(n = 74) isolated from blood culture samples were included. Klebsiella pneumoniae NCTC 13438 was used as a positive control and Escherichia coli ATCC 25922 as a negative control. First, Imipenem, meropenem, and ertapenem MIC values of strains were determined. Then bla_KPC, bla_OXA-48, and/or bla_NDM genes were investigated with PCR. Carbapenemase activity was investigated in strains with the newly developed method using MALDI-TOF MS. The performance of the new method was evaluated for both the second and fourth hours of the incubation period.

RESULTS

While 65 strains were found resistant to tested carbapenems, nine of them were susceptible. Of the 65 resistant strains, 57 had bla_OXA-48, 15 had bla_NDM, and four had bla_KPC genes. Bla_OXA-48 and bla_NDM genes were detected together in 11 strains. Bla_OXA-48, bla_NDM, and bla_KPC genes were not detected in any of the susceptible strains. The sensitivity and specificity of MALDI-TOF MS at the second hour were 83.1% and 100%, respectively. At the fourth hour, the sensitivity and specificity of MALDI-TOF MS were 100%. No false-positive results were observed.

CONCLUSION

The sensitivity of the method at the fourth hour was better than the second hour. The false-negative results observed in the second hour disappeared when the incubation period was extended to 4 h. MALDI-TOF MS which is still under development is a fast, cost-effective, promising method for the detection of carbapenemase activity.

Comparison of ertapenem non-susceptibility with 2-mercaptopropionic acid phenotypic tests in predicting NDM-1 and IMP-1 production in clinical isolates of Escherichia coli

Background:

A routine phenotypic test has not been recommended for the detection of metallo-β-lactamases (MBLs) producing Enterobacteriaceae species such as Escherichia coli. The current study was conducted to compare the 2-mercaptopropionic acid (2-MPA) phenotypic method and ertapenem non-susceptibility test with polymerase chain reaction in predicting the production of MBLs in clinical isolates of E. coli.

Methods:

Antimicrobial susceptibility test for beta-lactam antibiotics were performed by disk diffusion method. All isolates which showed inhibition zones of ≤ 22 mm for CAZ and ≤ 27 mm for CTX were considered potential MBLs producing isolates. The production of MBLs was confirmed using 2-MPA compound. Also, susceptibility to ertapenem was evaluated in all isolates. Conventional PCR was performed to detect blaIMP-1 and/or blaNDM-1 genes in all potential MBLs producing E. coli isolates.

Results:

Of 259, 138 (53.3%) isolates were potential MBLs producing bacteria. One hundred and fifteen out of 138 (83.3%) isolates were susceptible to ertapenem. MBLs production was confirmed in 75/138 (54.4%) isolates by 2-MPA phenotypic method. The blaNDM-1 or/and blaIMP-1 genes were found in 30/75(40%) and 39/115(33.9%) isolates which were confirmed by 2-MPA and were susceptible to ertapenem, respectively. The sensitivity of 2-MPA method and ertapenem non-susceptibility test compared with PCR were 65.2% and 15.2%, and the specificity was 52.1% versus 82.6%, respectively.

Conclusion:

This study demonstrated that the 2-MPA phenotypic method does not have acceptable sensitivity and specificity in comparison with PCR, but its results are more reliable for the detection of MBL producing E. coli isolates compared with non-susceptibility to ertapenem.

The effect of prophylaxis with ertapenem versus cefuroxime/metronidazole on intestinal carriage of carbapenem-resistant or third-generation-cephalosporin-resistant Enterobacterales after colorectal surgery

OBJECTIVES

Compared to cephalosporin-based prophylaxis, ertapenem prophylaxis lowers the risk of surgical site infection among carriers of extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PEs) undergoing colorectal surgery. We aimed to determine whether ertapenem prophylaxis leads to increased postoperative colonization with carbapenem-resistant Enterobacterales (CREs) and third-generation-cephalosporin-resistant Enterobacterales (3GCR-Es).

METHODS

This study was nested within a quality improvement study of prophylaxis for ESBL-PE carriers undergoing colorectal surgery. Patients were screened 4-6 days after surgery for carriage of ESBL-PEs or other 3GCR-Es and CREs. When CREs were detected, pre- and postsurgical clones were compared using Fourier-transform infrared (FT-IR) spectroscopy.

RESULTS

The sample consisted of 56 patients who carried ESBL-PEs before surgery and received cefuroxime/metronidazole prophylaxis (Group 1), 66 who carried ESBL-PEs before surgery and received ertapenem (Group 2), and 103 ESBL-PE non-carriers who received cefuroxime/metronidazole prophylaxis (Group 3). CRE carriage was detected postoperatively in one patient (1.5%) in Group 2 versus eight patients (14.3%) in Group 1 (RD -12.8%; 95%CI -22.4% to -3.1%). For seven out of nine patients, preoperative ESBL-PE and postoperative CRE isolates were compared; in five of them, the pre- and postoperative clones were identical. Postoperative 3GCR-E carriage was detected in 37 patients (56.1%) in Group 2 versus 46 patients in Group 1 (82.1%) (aRD -20.7%, 95%CI -37.3% to -4.1%).

CONCLUSIONS

Among ESBL-PE carriers undergoing colorectal surgery, detection of short-term postsurgical colonization by CREs and 3GCR-Es was significantly lower among patients who received ertapenem prophylaxis than those who received cephalosporin-metronidazole prophylaxis. Resistance development in a colonizing bacterial clone, rather than carbapenemase acquisition, was the major mechanism of carbapenem resistance.

Escherichia fergusonii in a patient with a traumatic amputation of the right pelvic limb

El nombre de Escherichia fergusonii es en honor del microbiólogo William H. Ferguson. Es un bacilo gramnegativo, móvil, oxidasa negativo, catalasa positivo, reductor de nitrato y fermentador, oportunista que se asocia a infecciones de sitio quirúrgico. Una niña de 12 años fue remitida a un servicio de urgencias ortopédicas en la Ciudad de México con amputación traumática de la extremidad pélvica derecha. Tenía exposición ósea y requirió varios desbridamientos quirúrgicos. En el hueso y el tejido muscular se aisló E. fergusonii solo resistente a trimetoprima-sulfametoxazol y ampicilina, más otros gérmenes. Recibió un mes de ertapenem más ampicilina, con marcada mejoría.

The name of Escherichia fergusonii was in honor of the microbiologist William H. Ferguson. It is a gram-negative rod, motile, oxidase negative,catalase positive, nitrate reducing and fermenter. Opportunistic that is associated with surgical site infections. A 12-year-old girl was referred to an orthopedic emergency department in Mexico City with a traumatic amputation of the right leg, she had bone exposure and required several surgical debridements. From bone and soft tissue samples we isolated E. fergusonii only resistant to trimethoprim sulfamethoxazole and ampicillin, and other germs. She received a month of ertapenem plus ampicillin with marked improvement.

Ertapenem and Faropenem against Mycobacterium tuberculosis: in vitro testing and comparison by macro and microdilution

Background

Interest in carbapenems has been rising in the last few years due to the emergence of drug resistant tuberculosis. Ertapenem (ETP), given once a day parenteral, and faropenem (FAR), oral, have a better administration profile than meropenem (MEM), imipenem (IPM) and doripenem (DOR). The addition of amoxicillin-clavulanate (AMC) inhibits the hydrolysis by the carbapenemase present in Mycobacterium tuberculosis (MTB).

The aim of this study was to determine the in vitro activity of ETP and FAR against susceptible and resistant clinical MTB strains by two widely use methodologies, the BACTEC960 MGIT and microdilution.

Results

19 clinical isolates with different susceptibility profiles and H37Rv were included. Minimal inhibitory concentration (MIC) testing was performed using two methods of different concentrations of ETP and FAR with and without AMC.

MIC50 was 2 and 8 for FAR with and without AMC by both methods. MIC90 was > 16 and > 8 by microdilution and MGIT respectively and did not change after AMC addition.

18/20 samples were resistant to the highest concentration of ETP, with and without AMC. Half of the samples had some susceptibility to FAR; addition of AMC further reduced the MIC level in seven isolates.

10/20 isolates showed susceptibility to FAR and the addition of AMC further reduced the MIC in 7 isolates. However, most of the MICs were near the limit of effectiveness (8 μg/mL).

Resistance to FAR was associated with resistance to MEM (p = 0.04) but not to resistance profiles of other drugs, including M/XDR status.

Conclusions

The lack of ETP activity may be associated with its degradation, independent of carbapenemase, during incubation.

No susceptibility pattern to traditional drugs can predict susceptibility to FAR and susceptibility testing is not routinely available. PK/PD studies are needed as reaching the concentrations tested in these experiments may be challenging.

This work highlighted some of the limitations of carbapenem use. More evidence is needed to clarify their true impact in TB treatment and outcome, considering the financial burden, complications and microbiota changes associated with their use.

A Physiologically Based Pharmacokinetic Model of Ertapenem in Pediatric Patients With Renal Impairment

Ertapenem is a widely used antibiotic; however, its pharmacokinetics has not been fully evaluated in children with renal impairment. A physiologically based pharmacokinetic (PBPK) model of ertapenem was established and validated to simulate its disposition in the healthy population and adults with renal impairment, as well as to predict the exposure in pediatric patients with renal impairment. The simulated PBPK modeling results and the observed data of ertapenem after intravenous administration of various regimens were consistent according to the fold error values of less than 2. Furthermore, %T > MIC of ertapenem was evaluated using the PBPK model. The C_max was not significantly changed in pediatric patients with renal impairment compared to healthy children. However, the AUC was 1.42-fold, 1.84-fold, 2.37-fold, and 3.52-fold higher in mild, moderate, severe renal impairment, and end-stage renal disease, respectively, than that in healthy children and the doses of ertapenem were reduced to 13 mg/kg b.i.d, 9 mg/kg b.i.d, 6 mg/kg b.i.d, and 5 mg/kg b.i.d, respectively. The probability of achieving 40%T > MIC (MIC ≤ 4 μg/mL) was nearly 100% throughout the recommended dosing interval. In conclusion, our model can be used as a tool to generate better predictions for the most effective ertapenem dosing in pediatric patients.

Validation and clinical application of a multiplex high performance liquid chromatography - tandem mass spectrometry assay for the monitoring of plasma concentrations of 12 antibiotics in patients with severe bacterial infections

OBJECTIVE

Unpredictable pharmacokinetics of antibiotics in patients with life-threatening bacterial infections is associated with drug under- or overdosing. Therapeutic drug monitoring (TDM) may guide dosing adjustment aimed at maximizing antibacterial efficacy and minimizing toxicity. Rapid and accurate analytical methods are key for real-time TDM. Our objective was to develop a robust high-performance liquid chromatography-tandem mass spectrometry method (HPLC-MS/MS) for multiplex quantification of plasma concentrations of 12 antibiotics: imipenem/cilastatin, meropenem, ertapenem, cefepime, ceftazidime, ceftriaxone, piperacillin/tazobactam, amoxicillin, flucloxacillin, rifampicin, daptomycin.

METHODS

A single extraction procedure consisting in methanol plasma protein precipitation and H₂O dilution was used for all analytes. After chromatographic separation on an Acquity UPLC HSS-T3 2.1 × 50 mm, 1.8 µm (Waters®) column, quantification was performed by electro-spray ionisation-triple quadrupole mass spectrometry with selected reaction monitoring detection. Antibiotics were divided in two pools of calibration according to the frequency of analyses requests in the hospital routine antibiotic TDM program. Stable isotopically-labelled analogues were used as internal standards. A single analytical run lasted less than 9 min.

RESULTS

The method was validated based on FDA recommendations, including assessment of extraction yield (96-113.8%), matrix effects, and analytical recovery (86.3-99.6%). The method was sensitive (lower limits of quantification 0.02-0.5 µg/mL), accurate (intra/inter-assay bias -11.3 to +12.7%) and precise (intra/inter-assay CVs 2.1-11.5%) over the clinically relevant plasma concentration ranges (upper limits of quantification 20-160 µg/mL). The application of the TDM assay was illustrated with clinical cases that highlight the impact on patients' management of an analytical assay providing information with short turn-around time on antibiotic plasma concentration.

CONCLUSION

This simple, robust high-throughput multiplex HPLC-MS/MS assay for simultaneous quantification of plasma concentrations of 12 daily used antibiotics is optimally suited for clinically efficient real-time TDM.

Evaluation of alternative antibiotics for susceptibility of gonococcal isolates from China

The efficacy of the currently recommended first-line treatments for gonococcal infections - ceftriaxone monotherapy or ceftriaxone/azithromycin dual therapy - is waning rapidly, and efficient alternative antimicrobials are needed urgently to ensure that future treatment of gonorrhoea remains available. As such, the aim of this study was to screen alternative clinically approved antimicrobials for in-vitro activity against Neisseria gonorrhoeae. The susceptibility levels of 504 clinical isolates from Zhejiang Province, China to ertapenem, tigecycline, gentamicin, fosfomycin, gemifloxacin, doxycycline and rifampicin were investigated using the agar dilution method. The presence of resistance determinants was identified by polymerase chain reaction and sequencing. The minimum inhibitory concentration inhibiting 90% of growth (MIC₉₀) was 0.06 mg/L for ertapenem, 0.25 mg/L for tigecycline, 16 mg/L for doxycycline, 4 mg/L for gemifloxacin, 16 mg/L for gentamicin, 32 mg/L for fosfomycin and 128 mg/L for rifampicin. All strains appeared to be susceptible to tigecycline (MIC ≤0.5 mg/L), while a poor correlation between tigecycline and tetracycline susceptibility was observed, indicating that tetracycline resistance determinants have little impact on tigecycline susceptibility. For ertapenem, 30 isolates showed an MIC >0.125 mg/L, but the correlation between ertapenem and ceftriaxone susceptibility was low and only two strains showed an MIC >0.125 mg/L for both antibiotics. Therefore, it appeared that most ceftriaxone-resistant isolates were still susceptible to ertapenem. In conclusion, tigecycline and ertapenem showed good activity against N. gonorrhoeae and limited cross-resistance with previously used antibiotics. Therefore, they might be interesting candidates for further evaluation of their suitability as alternative antigonococcal therapies.

Clinical outcomes following treatment of Enterobacter species pneumonia with piperacillin/tazobactam compared to cefepime or ertapenem

BACKGROUND

Enterobacter spp. are a common cause of nosocomial pneumonia and treatment can be complicated by AmpC resistance. Carbapenems are the treatment of choice; however, alternatives are needed. Cefepime has been shown to be non-inferior to carbapenems. There are limited data to support the use of piperacillin/tazobactam. The objective of this study was to determine if piperacillin/tazobactam is non-inferior to cefepime or ertapenem for Enterobacter pneumonia treatment.

OBJECTIVES

To compare the rate of clinical cure in patients with Enterobacter pneumonia receiving definitive treatment with piperacillin/tazobactam, cefepime, or ertapenem. Secondary outcomes included hospital mortality, infection-related length of stay, duration of mechanical ventilation, recurrent pneumonia, and resistance.

METHODS

Retrospective, single-center study.

RESULTS

Of 114 patients included, 59 received definitive treatment with piperacillin/tazobactam and 55 received cefepime or ertapenem. There was no difference in the proportion of patients who achieved clinical cure in the piperacillin/tazobactam group compared to the cefepime or ertapenem group (76.3% vs. 87.3%, P = 0.13). Treatment group was not associated with clinical cure when controlling for confounders in multivariable logistic regression (adjusted odds ratio [OR] 0.59, 95% confidence interval [CI] 0.15-2.37). The rate of recurrent pneumonia was 11.4% in the piperacillin/tazobactam group and 6.7% in the cefepime or ertapenem group (P = 0.48). Other secondary outcomes did not differ between the groups.

CONCLUSIONS

In this retrospective study of patients with Enterobacter pneumonia, clinical cure with piperacillin/tazobactam was comparable to that with cefepime or ertapenem; however, a prospective trial with a larger population is needed to determine if definitive treatment with piperacillin/tazobactam is non-inferior to definitive treatment with cefepime or ertapenem.

Management of carbapenem-resistant Enterobacteriaceae infections

BACKGROUND

Carbapenem resistance is defined as in vitro non-susceptibility to any carbapenem and/or documented production of a carbapenemase. This feature has rapidly spread worldwide among clinical isolates of Enterobacteriaceae, mostly Klebsiella spp., and is associated with diverse molecular mechanisms. Carbapenem resistance is often associated with resistance to all traditional β-lactams and other classes of antibiotics, denoting a typical example of an extensively drug-resistant phenotype.

OBJECTIVES

To summarize and interpret in a balanced manner the most clinically relevant data in terms of carbapenem-resistant Enterobacteriaceae (CRE) infection management.

SOURCES

Data were extracted by PubMed and clinicaltrials.gov search and manual scrutiny among references of analysed articles.

CONTENT

Features of newer and older, rediscovered antimicrobial options for CRE are described. Observational studies and randomized clinical trials (RCT) of CRE treatment are summarized, with a specific focus on the effects of monotherapy compared with combination treatment.

IMPLICATIONS

The available evidence on the current management of CRE mostly comes from observational, non-comparative, retrospective, small studies, with a high risk of selection bias. Very little evidence comes from RCT. Conflicting results of RCT and observational studies call for caution before combination therapies are deemed superior to monotherapy. Data on newer agents have spurred enthusiasm but remain limited as concerns severe CRE infections. A balanced approach should guide the clinician in the choice of old or new drugs, and of monotherapies or combination regimens. Efforts should be made to perform adequately sized clinical trials answering well-defined research questions.

Hypermucoviscous polymyxin-resistant Klebsiella pneumoniae from Kolkata, India: Genomic and phenotypic analysis

OBJECTIVES

Here we report the draft genome sequence of a colistin-resistant hypermucoviscous Klebsiella pneumoniae isolated from a hospitalised patient with acute kidney injury in Kolkata, India.

METHODS

Whole genomic DNA was sequenced using an Illumina HiSeq platform. The generated reads were de novo assembled using SPAdes v.3.7.1. Genome annotation was performed using the NCBI Prokaryote Genome Annotation Pipeline (PGAP) v.4.6. The sequence type (ST), capsular type, antimicrobial resistance and virulence-related genes were predicted from the genome sequence.

RESULTS

Klebsiella pneumoniae KP26 belonged to ST147. The assembly comprised 63 contigs (>1000 bp) with a total read length of 5 560 935 bp and a total of 5399 coding sequences. The isolate was resistant to most β-lactams, aminoglycosides, quinolones, fosfomycin, trimethoprim, sulphonamides and polymyxins. No mcr genes were detected in the genome.

CONCLUSION

Isolate KP26 is a hypermucoviscous, multidrug-resistant K. pneumoniae strain that may represent an emerging high-risk clone associated with severe infections in India.

The 1-β-methyl group confers a lower affinity of l,d-transpeptidase LdtMt2 for ertapenem than for imipenem

L,D-transpeptidases, widely distributed in bacteria and even in the difficult-to-treat ESKAPE pathogens, can confer antibacterial resistance against the traditional β-lactam antibiotics through bypass of the 4 → 3 transpeptide linkage. Ldt_Mt2, a l,d-transpeptidase in Mycobacteria tuberculosis, is essential for bacterial virulence and is considered as a potential anti-tuberculosis target inhibited by carbapenems. Diverse interaction modes between carbapenems and Ldt_Mt2 have been reported, there are only limited evidences to validate those interaction modes. Herein, we identified the stable binding states of two carbapenems, imipenem and ertapenem, via crystallographic and biochemical studies, discovered that they adopt similar binding conformations. We further demonstrate the absence of the 1-β-methyl group in imipenem and the presence of both Y308 and Y318 residues in Ldt_Mt2 synergistically resulted in one order of magnitude higher affinity for imipenem than ertapenem. Our study provides a structural basis for the rational drug design and evolvement of novel carbapenems against bacterial L,D-transpeptidases.

Ertapenem for osteoarticular infections in obese patients: a pharmacokinetic study of plasma and bone concentrations

PURPOSE

Ertapenem is used off-label to treat osteoarticular infections but there are few pharmacokinetic (PK) data to guide optimal dosing strategies in patients who may be obese with multiple co-morbidities including diabetes and peripheral vascular disease.

METHODS

Participants undergoing lower limb amputation or elective joint arthroplasty received a dose of intravenous ertapenem prior to surgery. Eight plasma samples were collected over 24 h, together with at least one bone sample per patient. Ertapenem concentrations in plasma and bone were measured using liquid-chromatography/mass-spectroscopy and analysed using non-linear mixed effects PK modelling.

RESULTS

Plasma and bone concentrations were obtained from 10 participants. The final population PK model showed that a fat free body mass was the most appropriate body size adjustment. Ertapenem diffused rapidly into bone but concentrations throughout the 24 h dosing period were on average 40-fold higher in plasma, corresponding to a bone to plasma ratio of 0.025, and highly variable between individuals. Simulations demonstrated a high probability of target attainment (PTA) for free plasma concentrations when the minimum inhibitory concentrations (MIC) were ≤ 0.25 mg/L. By contrast, at MICs of 0.5 mg/L and ≥ 1 mg/L, the fractions of patients attaining this target was ~ 80% and 40%, respectively. In bone, the PTA was ≤ 45% when the MIC was ≥ 0.25 mg/L.

CONCLUSION

Local bone and free plasma concentrations appear adequate for osteoarticular infections where Enterobacteriaceae are the main causative pathogens, but for Staphylococcus aureus and other bacteria, conventional dosing may lead to inadequate PTA.

Ertapenem-associated neurotoxicity in the spinal cord injury (SCI) population: A case series

Context Ertapenem, a broad spectrum carbapenem antibiotic, is used often in Spinal Cord Injury (SCI) patients due to increased risk factors for multi-drug resistant (MDR) infections in this population. Neurotoxicity, specifically seizures, due to ertapenem is a known adverse effect and has been described previously. Other manifestations such as delirium and visual hallucinations have rarely been reported, and no literature, to the best of our knowledge, specifically describes these effects solely in the SCI population. Findings Four cases of mental status changes and hallucinations in SCI patients attributed to ertapenem therapy are described. Onset of symptoms began between one and six days following initiation of ertapenem and resolved between two to 42 days following discontinuation. Based on the Naranjo probability scale, a probable relationship exists between the adverse events and ertapenem for three out of the four cases. Possible overestimation of renal function and hypoalbuminemia may be contributing factors to the noted adverse reactions. Conclusion/Clinical Relevance The cases described highlight the importance of recognizing ertapenem-associated hallucinations in SCI patients. The population is particularly vulnerable due to risk factors for MDR infections necessitating ertapenem use, possible overestimation of renal function, and a high prevalence of hypoalbuminemia.

Double carbapenem as a rescue strategy for the treatment of severe carbapenemase-producing Klebsiella pneumoniae infections: a two-center, matched case-control study

Background

Recent reports have suggested the efficacy of a double carbapenem (DC) combination, including ertapenem, for the treatment of carbapenem-resistant Klebsiella pneumoniae (CR-Kp) infections. We aimed to evaluate the clinical impact of such a regimen in critically ill patients.

Methods

This case–control (1:2), observational, two-center study involved critically ill adults with a microbiologically documented CR-Kp invasive infection treated with the DC regimen matched with those receiving a standard treatment (ST) (i.e., colistin, tigecycline, or gentamicin).

Results

The primary end point was 28-day mortality. Secondary outcomes were clinical cure, microbiological eradication, duration of mechanical ventilation and of vasopressors, and 90-day mortality. Forty-eight patients treated with DC were matched with 96 controls. Occurrence of septic shock at infection and high procalcitonin levels were significantly more frequent in patients receiving DC treatment (p < 0.01). The 28-day mortality was significantly higher in patients receiving ST compared with the DC group (47.9% vs 29.2%, p = 0.04). Similarly, clinical cure and microbiological eradication were significantly higher when DC was used in patients infected with CR-Kp strains resistant to colistin (13/20 (65%) vs 10/32 (31.3%), p = 0.03 and 11/19 (57.9%) vs 7/27 (25.9%), p = 0.04, respectively). In the logistic regression and multivariate Cox-regression models, the DC regimen was associated with a reduction in 28-day mortality (OR 0.33, 95% CI 0.13–0.87 and OR 0.43, 95% CI 0.23–0.79, respectively).

Conclusions

Improved 28-day mortality was associated with the DC regimen compared with ST for severe CR-Kp infections. A randomized trial is needed to confirm these observational results.

Trial registration

ClinicalTrials.gov NCT03094494. Registered 28 March 2017.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1769-z) contains supplementary material, which is available to authorized users.

Randomized controlled trial of piperacillin-tazobactam, cefepime and ertapenem for the treatment of urinary tract infection caused by extended-spectrum beta-lactamase-producing Escherichia coli

BACKGROUND

Due to limited therapeutic options, the spread of extended-spectrum beta-lactamases (ESBLs) have become a major public health concern. We conducted a prospective, randomized, open-label comparison of the therapeutic efficacy of piperacillin-tazobactam (PTZ), cefepime, and ertapenem in febrile nosocomial urinary tract infection with ESBL-producing Escherichia coli (ESBL-EC).

METHODS

This study was conducted at three university hospitals between January 2013 and August 2015. Hospitalized adult patients presenting with fever were screened for healthcare-associated urinary tract infection (HA-UTI). When ESBL-EC was solely detected and susceptible to a randomized antibiotic in vitro, the case was included in the final analysis. Participants were treated for 10-14 days with PTZ, cefepime, or ertapenem.

RESULTS

A total of 66 participants were evenly assigned to the PTZ and ertapenem treatment groups. After the recruitment of six participants, assignment to the cefepime treatment group was stopped because of an unexpectedly high treatment failure rate. The baseline characteristics of these participants did not differ from participants in other treatment groups. The clinical and microbiological response to PTZ treatment was estimated to be 94% and was similar to the response to ertapenem treatment. The efficacy of cefepime was 33.3%. In the cefepime group, age, Charlson comorbidity index, genotype, and minimal inhibitory concentration (MIC) did not significantly affect the success of treatment. Similarly, genotype seemed to be irrelevant with respect to clinical outcome in the PTZ group. Expired cases tended to involve septic shock with a high Charlson comorbidity index and high MIC.

CONCLUSION

Results from this study suggest that PTZ is effective in the treatment of urinary tract infection caused by ESBL-EC when the in vitro test indicates susceptibility. In addition, cefepime should not be used as an alternative treatment for urinary tract infection caused by ESBL-EC.

TRIAL REGISTRATION

The trial was registered with the Clinical Research Information Service of Korea Centers for Disease Control and Prevention. (KCT0001895).

Resistance among Gram-negative ESKAPE pathogens isolated from hospitalized patients with intra-abdominal and urinary tract infections in Latin American countries: SMART 2013-2015

Gram-negative ESKAPE pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are important etiologic agents of nosocomial infection that are frequently resistant to broad-spectrum antimicrobial agents. Gram-negative ESKAPE pathogens were collected from hospitalized patients in 11 Latin American countries from 2013 to 2015 as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART) global surveillance program. In total, 2113 isolates from intra-abdominal infections (IAI) and 970 isolates from urinary tract infections (UTI) were tested against antimicrobial agents using standardized CLSI broth microdilution methodology. Of the agents tested, amikacin demonstrated the highest rates of susceptibility (%) for K. pneumoniae (92.2, 92.3), Enterobacter spp. (97.5, 92.1), and P. aeruginosa (85.3, 75.2) isolates from both IAI and UTI, respectively. Ertapenem (68.5, 62.6) and imipenem (79.2, 75.9) showed substantially higher rates of susceptibility (%) than other β-lactams, including piperacillin-tazobactam (35.9, 37.4) against ESBL-positive isolates of K. pneumoniae from IAI and UTI, respectively. Rates of susceptibility to all agents tested against A. baumannii were ≤30.9%. Gram-negative ESKAPE pathogens isolated from Latin America demonstrated compromised in vitro susceptibility to commonly prescribed broad-spectrum, parenteral antimicrobial agents. Continued surveillance is warranted. New antimicrobial agents with potent activity against Gram-negative ESKAPE pathogens are urgently needed.

Efficacy and safety of de-escalation therapy to ertapenem for treatment of infections caused by extended-spectrum-β-lactamase-producing Enterobacteriaceae: an open-label randomized controlled trial

Background

Carbapenem antibiotics are considered the treatment of choice for serious extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria (GNB) infections. The study objectives were to evaluate efficacy and safety of de-escalation therapy to ertapenem for treatment of infections caused by extended-spectrum-β-lactamase-producing Enterobacteriaceae.

Methods

We conducted a randomized controlled trial of adult patients with documented ESBL-producing Enterobacteriaceae infections who had received any group 2 carbapenem for less than 96 h. In the intervention group, the previously-prescribed group 2 carbapenem was de-escalated to ertapenem. In the control group, the group 2 carbapenem was continued.

Results

During June 2011–December 2014, 32 patients were randomized to the de-escalation group and 34 to the control group. Most common sites of infection were urinary tract infection (42%). Characteristics of both groups were comparable. By using a 15% predefined margin, ertapenem was non-inferior to control group regarding the clinical cure rate (%Δ = 14.0 [95% confidence interval: −2.4 to 31.1]), the microbiological eradication rate (%Δ = 4.1 [−5.0 to 13.4]), and the superimposed infection rate (%Δ = −16.5 [−38.4 to 5.3]). Patients in the de-escalation group had a significantly lower 28-day mortality rate (9.4% vs. 29.4%; P = .05), a significantly shorter median length of stay (16.5 days [4.0–73.25] vs. 20.0 days [1.0–112.25]; P = .04), and a significantly lower defined daily dose of carbapenem use (12.9 ± 8.9 vs. 18.4 ± 12.6; P = .05).

Conclusions

Ertapenem could be safely used as de-escalation therapy for ESBL-producing Enterobacteriaceae infections, once the susceptibility profiles are known. Future studies are needed to investigate ertapenem efficacy against ESBL-producing Enterobacteriaceae pneumonia to determine its applicability in life-threatening conditions.

Trial registration

ClinicalTrials.gov identifier: NCT01297842. Registered on 14 February 2011. First patient enrolled on 27 June 2011.

Role of piperacillin/tazobactam as a carbapenem-sparing antibiotic for treatment of acute pyelonephritis due to extended-spectrum β-lactamase-producing Escherichia coli

Extended-spectrum β-lactamase-producing Escherichia coli (ESBL-Ec) is a frequent cause of acute pyelonephritis (APN), requiring carbapenem therapy. However, alternatives to carbapenems are needed due to the emergence of carbapenemase-producing micro-organisms. The purpose of this study was to compare the clinical efficacy of piperacillin/tazobactam (TZP) versus ertapenem in the treatment of adult patients with APN caused by ESBL-Ec. A retrospective observational study of APN caused by ESBL-Ec susceptible to TZP was performed at a university-affiliated hospital in the Republic of Korea between February 2011 and June 2013. All adult patients initially treated with in vitro-active TZP were compared with those treated with ertapenem to evaluate antibiotic clinical efficacy. The primary endpoint was treatment failure, defined as a composite of in-hospital mortality, change of initial antibiotic regimen and microbiological eradication failure. During the study period, 68 patients prescribed TZP and 82 patients prescribed ertapenem were eligible for inclusion in the study. There was no significant difference between the two treatment groups in the occurrence of in-hospital mortality, change of initial antibiotic regimen or microbiological eradication failure. In the multivariate analyses, predictors associated with treatment failure included septic shock [odds ratio (OR) = 4.27, 95% confidence interval (CI) 1.66-10.99] and recent administration of immunosuppressive agents (OR = 2.84, 95% CI 1.02-7.91). However, the type of antibiotic was not associated with treatment failure. TZP could be an effective alternative to ertapenem for the treatment of APN caused by ESBL-Ec, sparing carbapenem consumption in the multidrug-resistant era.

Cross-reactivity and Tolerability of Ertapenem in Patients With IgE-Mediated Hypersensitivity to β-Lactams

BACKGROUND AND OBJECTIVE

Administration of carbapenems to β-lactam-allergic patients has always been considered potentially harmful because of a 47.4% rate of cross-reactivity to imipenem reported in a single study. Nevertheless, recent studies have shown that the rate of cross-reactivity of imipenem and meropenem with penicillins is lower than 1%. The aim of this study was to evaluate the possibility of using ertapenem in patients with an established IgE-mediated β-lactam allergy.

PATIENTS AND METHODS

We studied all participants who came to our allergy unit and had a clinical history of immediate hypersensitivity reactions to β-lactams. The inclusion criteria were a positive skin test result to at least 1 β-lactam molecule and/or positive specific IgE (when available). All participants underwent immediate-type skin tests with several β-lactam molecules including ertapenem. Challenges with intravenous ertapenem were performed on 2 different days in patients with negative skin test results.

RESULTS

We examined 49 patients with a clinical history of immediate reactions to β-lactams. All the patients had positive skin tests and/or positive specific IgE to at least 1 β-lactam reagent and negative carbapenem skin tests. Thirty-six patients agreed to undergo the challenges and 35 tolerated the full dose of ertapenem.

CONCLUSIONS

The practice of avoiding carbapenems in patients with β-lactam allergy should be abandoned considering the very low rate of cross-reactivity. β-Lactam-allergic patients who need ertapenem therapy should undergo skin tests and, if negative, a graded challenge to assess tolerability.

Plasma and intraprostatic concentrations of ertapenem following preoperative single dose administration: a single-centre prospective experience and clinical implications-the ERTAPRO study

The incidence of urinary tract infections caused by extended-spectrum β-lactamase (ESBL)-producing pathogens is increasing. These infections are associated with a long hospital stay in patients undergoing urological procedures. We aimed to demonstrate that significant intraprostatic diffusion of ertapenem is achieved after a single preoperative administration. A referred sample of 19 patients requiring surgery for benign prostatic hyperplasia was prospectively included. Patients received a 1 g intravenous (i.v.) dose of ertapenem 1 h (n = 10, group A) or 12 h (n = 9, group B) before blood and prostatic samples were collected. Plasma and intraprostatic concentrations of ertapenem were measured using LC-MS/MS. Intraprostatic concentrations were considered satisfactory when higher than the MIC90 value of urinary-targeted pathogens perioperatively and for 40% of the dosing interval. The Wilcoxon test and a pharmacokinetic predictive model were used. Median plasma concentrations of ertapenem were 144.3 mg/L (95% CI 126.5-157.9) in group A and 30.7 mg/L (95% CI 22.9-36.4) in group B (P < 0.001); median intraprostatic concentrations were 16.6 mg/L (95% CI 13.3-31.4 mg/L) and 4.2 mg/L (95% CI 3.1-4.9 mg/L), respectively (P < 0.001), which were above the MIC90 values of bacteria, including ESBL-producers, during surgery and for 40% of the dosing interval. The plasma-to-prostate concentration ratio was not significantly different between groups (P = 0.97). Single-dose i.v. ertapenem reached satisfactory intraprostatic concentrations, suggesting that it could be a relevant prophylactic strategy for carriers of ESBL-producing bacteria undergoing prostatic procedures, which needs to be confirmed by further prospective trials.

Ertapenem in outpatient parenteral antimicrobial therapy for complicated urinary tract infections

BACKGROUND

Ertapenem is a broad-spectrum antibiotic that is increasingly being utilized. Its dosing convenience renders it suitable for outpatient therapy, and its pharmacokinetic characteristics favour its use against complicated urinary tract infections (cUTIs). Despite this, sufficient clinical data are lacking for its use against cUTIs in the outpatient setting. We assessed the microbiological and clinical cure rates associated with ertapenem treatment for cUTIs in two outpatient parenteral antimicrobial therapy (OPAT) departments.

METHODS

We undertook a prospective observational study of adult patients who received ertapenem for cUTIs between August 2010 and August 2014. Data on patient characteristics, clinical progress and microbiological results were collected and analysed.

RESULTS

Sixty-one patients were enrolled. The median age was 59 years (range 24, 83) and 61% were male. The most common diagnoses were pyelonephritis (39%) and prostatitis (15%). The most common causative organism was Escherichia coli (67%). Extended-spectrum β-lactamase (ESBL)-producing organisms were detected in 72% of infections. Microbiological cure was achieved in 67% overall, and was less likely in those with Klebsiella pneumoniae infection (OR = 0.21 [95%CI: 0.05 to 0.85] p = 0.029). Clinical cure was observed in 92% of patients.

CONCLUSION

In this study of treating cUTIs with ertapenem, we have demonstrated good clinical outcomes. A lower than expected microbiological cure rate was observed in those with Klebsiella pneumoniae infection.

Ertapenem usage in cancer patients with and without neutropenia: a report on 97 cases from a comprehensive cancer center

PURPOSE

Ertapenem is being increasingly utilized in cancer patients, but published data regarding its usage are limited. Our objective was to describe the various indications for ertapenem therapy and its safety and efficacy in cancer patients.

METHODS

We conducted a retrospective cohort study of cancer patients who received monotherapy with ertapenem for at least 72 h, between January 2007 and February 2013.

RESULTS

Among 97 unique patients who received ertapenem monotherapy, the most common indications were: (1) To facilitate discharge from the hospital of stable patients still requiring antimicrobial therapy (46 %). (2) Primary therapy of various documented infections (bacteremia, pneumonia, urinary tract infection, skin and skin structure infection) with ertapenem (28 %). (3) De-escalation from a different broad-spectrum agent or regimen to ertapenem within the hospital setting in patients not ready for discharge (25 %). The median age of the 97 patients studied was 59 years (range 9-87 years) with 52 % being men. Most patients had underlying hematologic malignancies (54 %), and 7 % were recipients of hematopoietic stem cell transplantation. Twenty-nine patients (30 %) were neutropenic, 26 % were diabetic, and 6 % had chronic lung disease. Primary ertapenem monotherapy was successful in all patients, de-escalation in 95.8 % of patients, and the strategy of discharge on outpatient therapy with ertapenem in 95.6 % of patients. Patients failing de-escalation or early discharge responded to alternative regimens. We documented no significant ertapenem associated toxicity or adverse events.

CONCLUSIONS

Ertapenem appears to be safe and effective for several indications in cancer patients.

Different antimicrobial susceptibility testing methods to detect ertapenem resistance in Enterobacteriaceae: VITEK2, MicroScan, Etest, disk diffusion, and broth microdilution

We investigated different antimicrobial susceptibility testing methods to detect ertapenem resistance in Enterobacteriaceae. A total of 72 Enterobacteriaceae isolates were collected from a clinical microbiology laboratory of a tertiary university hospital, all of which were detected ertapenem resistance by the VITEK2 system. Bacterial identification and antimicrobial susceptibility were determined using the VITEK2. Ertapenem susceptibility test was performed using the MicroScan, Etest and a disk diffusion test. Ertapenem MICs were confirmed using the broth microdilution (BMD). Sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) of each method for the detection of ertapenem resistance were calculated. Carbapenemases and AmpC β-lactamase were screened using phenotypic methods. Among the 72 isolates, 20 isolates (27.8%) were resistant to ertapenem. Etest showed high sensitivity and specificity (85.0% and 88.5%, respectively) and excellent concordance with BMD. The disk diffusion test had the lowest sensitivity of 50.0%. The VITEK2 showed the lowest essential and categorical agreement (30.5% and 27.8%, respectively). The MicroScan showed relatively good agreement with BMD compared to the VITEK2. Most category disagreements were minor errors. There were 3 very major errors in both the MicroScan and disk diffusion test. Only 1 isolate was positive for carbapenemase screening test and all of the isolates were positive for AmpC screening test. In conclusion, the detection of ertapenem resistance in Enterobacteriaceae has limitations using routine testing such as an automated system or disk diffusion. Confirmation of results by an additional MIC test is recommended for accurate resistance results of ertapenem.

Nosocomial extended-spectrum beta-lactamase-producing Klebsiella pneumoniae bacteremia in hemodialysis patients and the implications for antibiotic therapy

BACKGROUND

In the face of increasing treatment options for extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-Kp) hemodialysis (HD) access-related bacteremia, the difference in clinical effectiveness between ertapenem and flomoxef remains unclear. We conducted this retrospective study to determine their efficacies and treatment outcomes.

METHODS

Patients on maintenance HD with fistula-, graft-, or catheter-related ESBL-Kp bacteremia were enrolled. Data related to clinical features and antibiotic treatments were collected. Outcome was determined by mortality resulting from bacteremia during the 14-day period after the collection of the first positive blood culture for flomoxef-susceptible ESBL-Kp.

RESULTS

The 64 patients studied had severe septicemia as determined by the Pitt bacteremia score; 50% (32/64) were in the intensive care unit (ICU) at the time of bacteremia. Old age (>65 years; 57.8%), malnutrition (albumin<3.5g/dl; 92.2%), a history of severe illnesses (defined by shock, intubation, or ICU stay; 82.5%), and prolonged hospitalization prior to the onset of bacteremia (>30 days; 75%) were also highly prevalent. The study population comprised nine fistula-, 10 graft-, and 45 HD catheter-related bacteremia cases, and the mortality rate was high (38/64, 59.4%). The mortality rate was significantly higher in the flomoxef treatment group than in the ertapenem treatment group (22/30, 73% vs. 16/34, 47%, p<0.05). Among patients with catheter-related bacteremia, multivariate analyses revealed that flomoxef use (odds ratio (OR) 2.52, 95% confidence interval (CI) 1.34-35.17) and Pitt bacteremia score (OR 4.37, 95% CI 1.28-5.26) were independently associated with mortality.

CONCLUSIONS

In accordance with our previous study, our results have demonstrated the inferiority of flomoxef to carbapenems in the treatment of HD access-related ESBL-Kp bacteremia and provide an insight into the possibility of using ertapenem rather than flomoxef as an initial or de-escalating therapy for infections caused by ESBL-producing bacteria.

Clinical Efficacy of Ertapenem for Recurrent Cystitis Caused by Multidrug-Resistant Extended-Spectrum β-Lactamase-Producing Escherichia coli in Female Outpatients

Purpose

To evaluate the clinical outcomes of ertapenem administered as an outpatient parenteral antibiotic therapy for intractable cystitis caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli.

Materials and Methods

We retrospectively reviewed a case series of 3 years of therapeutic experience with ertapenem for intractable recurrent cystitis caused by ESBL-producing E. coli. Ertapenem 1 g/d was parenterally administered to the patients on an outpatient basis until the acquisition of symptomatic improvement and negative conversion of urine culture. Demographic and clinical characteristics of patients, antimicrobial resistance, and clinical response data were analyzed from the patients' medical records.

Results

During the course of this study, a total of 383 patients were diagnosed with cystitis, and 24 of them showed ESBL-producing E. coli (6.26%). The mean treatment duration of all patients was 8.5 days. The early clinical and microbiological cure rates 0 to 7 days after the end of treatment were 91.7% (22/24) and 90.9% (20/22), respectively. The late clinical and microbiological cure rates 4 to 6 weeks after the end of treatment were 72.2% (13/18) at both time points.

Conclusions

Parenteral ertapenem treatment can be an effective and well-tolerated treatment option for intractable recurrent cystitis by multidrug-resistant ESBL-producing E. coli.

Phase 3 study comparing tigecycline and ertapenem in patients with diabetic foot infections with and without osteomyelitis

A phase 3, randomized, double-blind trial was conducted in subjects with diabetic foot infections without osteomyelitis (primary study) or with osteomyelitis (substudy) to determine the efficacy and safety of parenteral (intravenous [iv]) tigecycline (150 mg once-daily) versus 1 g once-daily iv ertapenem ± vancomycin. Among 944 subjects in the primary study who received ≥1 dose of study drug, >85% had type 2 diabetes; ~90% had Perfusion, Extent, Depth/tissue loss, Infection, and Sensation infection grade 2 or 3; and ~20% reported prior antibiotic failure. For the clinically evaluable population at test-of-cure, 77.5% of tigecycline- and 82.5% of ertapenem ± vancomycin-treated subjects were cured. Corresponding rates for the clinical modified intent-to-treat population were 71.4% and 77.9%, respectively. Clinical cure rates in the substudy were low (<36%) for a subset of tigecycline-treated subjects with osteomyelitis. Nausea and vomiting occurred significantly more often after tigecycline treatment (P = 0.003 and P < 0.001, respectively), resulting in significantly higher discontinuation rates in the primary study (nausea P = 0.007, vomiting P < 0.001). In the primary study, tigecycline did not meet criteria for noninferiority compared with ertapenem ± vancomycin in the treatment of subjects with diabetic foot infections.

Evaluation of the potential impact of a carbapenem de-escalation program in an academic healthcare system

The primary objective of this analysis was to evaluate group 2 carbapenem usage and to model the impact that a formalized de-escalation protocol to ertapenem could potentially have on group 2 carbapenem usage in the hope of alleviating the selective pressure on Acinetobacter and Pseudomonas. This analysis was conducted in three hospitals within the Detroit Medical Center in 2009. Patients were considered candidates for de-escalation of carbapenem therapy when a group 2 carbapenem was utilized to treat Enterobacteriaceae, such as extended spectrum β-lactamase (ESBL)-producing organisms, or if cultures were negative in non-intensive care unit (ICU) patients. In total, 179 patients (28%) and 1074 patient-days (29%) were deemed eligible for de-escalation according to our pre-defined criteria. We concluded that preferential utilization of ertapenem in appropriate patients warranting carbapenem therapy has the potential to significantly decrease group 2 carbapenem usage at our institution.

Discordance in the minimal inhibitory concentrations of ertapenem for Enterobacter cloacae: Vitek 2 system versus Etest and agar dilution methods

Our objective was to compare the ertapenem minimal inhibitory concentrations (MICs) for Enterobacter cloacae isolates categorized intermediate or resistant to ertapenem when measured with the Vitek 2 system, with the MICs for these isolates when measured by two methods performed in agar medium: the Etest and agar plate dilution method (APDM). Overall, 50 E. cloacae isolates were included in the study. The mean MIC of ertapenem was 2.92±1.77μg/ml according to the Vitek 2 system, 0.94±0.84μg/ml according to the Etest strips, and 0.93±0.62μg/ml according to the APDM. Furthermore, the MICs determined by the Vitek 2 system were higher than the MICs determined by the two other methods for 96% of strains. Lastly, according to the Etest strips and APDM, 42% of E. cloacae were susceptible to ertapenem. No carbapenemase was identified by the screening method used. Using the Vitek 2 system to determine ertapenem MICs for E. cloacae can have potential consequences in terms of additional carbapenemase-detecting tests and antimicrobial therapy. It would be interesting to determine if the Vitek 2 system is more effective for the detection of carbapenemase producers with low-level carbapenem resistance than the two methods performed in agar medium.

Susceptibility of gram-negative aerobic bacilli from intra-abdominal pathogens to antimicrobial agents collected in the United States during 2011

OBJECTIVES

During 2011, a total of 1442 gram-negative pathogens from intra-abdominal infections were collected as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART) from 19 hospital sites within the United States. Susceptibility to ertapenem and comparators and molecular analysis of ertapenem resistant isolates was performed.

METHODS

Extended-spectrum beta-lactamase ESBL (ESBL) isolates were determined using the Clinical and Laboratory Standards Institute's recommended phenotypic test. Isolates were identified to the species level, and tested for antimicrobial susceptibility using custom MicroScan dehydrated broth microdilution panels ESBLs and carbapenemases were characterized using the Check-Points microarray. Strain typing of Klebsiella pneumoniae was performed by rep-PCR on the DiversiLab System.

RESULTS

The majority of isolates were Escherichia coli (36%), K. pneumoniae (18.6%), Pseudomonas aeruginosa (12.1%) and Enterobacter cloacae (8.4%). Incidence of ESBL-positive isolates was 12.7%, 9.7%, 3.6% and 3.1% for K. pneumoniae, E. coli, Proteus mirabilis and Klebsiella oxytoca, respectively. Against the majority of isolates and species tested, the most active antibiotics were amikacin, ertapenem, and imipenem, with the carbapenems being the most active in vitro, including against ESBL-positive isolates of E. coli. All other antibiotics exhibited diminished activity. Against K. pneumoniae, the carbapenems were notably less active against ESBL-positive isolates though their activity against this sub-population was still the highest of all antibiotics tested; however, 41.1% (14 of 34) of the phenotypically ESBL-positive K. pneumoniae co-produced a carbapenemase (KPC2 or KPC3), and >90% of the isolates producing only an ESBL remained susceptible to ertapenem.

CONCLUSIONS

Further monitoring of susceptibility of intra-abdominal isolates is warranted due to limited therapeutic options available to physicians.

Effect of experimentally induced hypovolemia on ertapenem tissue distribution using microdialysis in rats

Hypovolemia is a common event in critical care patients that may affect drug distribution and elimination. In order to better understand this issue the effect of hypovolemia on the plasma protein binding and tissue distribution of ertapenem was investigated in rats using microdialysis. Microdialysis probes were inserted into the jugular vein and hind leg muscle. Ertapenem recoveries in muscle and blood were determined in each rat by retrodialysis by drug before drug administration. Hypovolemia was induced in 6 rats by removing 40% of the initial blood volume over 30 min. Ertapenem was infused intravenously at a dose of 40 mg kg(-1) over 30 min, and microdialysis samples were collected for 310 min. The unbound concentration profiles in muscle and blood were virtually superimposed in both groups except at early time points. The ratios of the area under the concentration-time curve (AUC) for tissue to the AUC for blood were 0.7±0.2 and 0.8±0.2 for control and hypovolemic rats, respectively. Hypovolemia induced a 40% decrease in the clearance of ertapenem, with no statistically significant alteration of its volume of distribution. This study showed that ertapenem elimination was altered in hypovolemic rats, probably due to decreased renal blood flow, but its distribution characteristics were not. Unbound concentrations of ertapenem in blood and muscle were always virtually identical.

Design, synthesis, and evaluation of prodrugs of ertapenem

Carbapenems are intravenous lifesaving hospital antibiotics. Once patients leave the hospital, they are sent home with antibiotics other than carbapenems since they cannot be administered orally due to lack of oral absorption primarily because of very highly polarity. A prodrug approach is a bona fide strategy to improve oral absorption of compounds. Design and synthesis, in vitro and in vivo evaluation of diversified prodrugs of ertapenem, one of the only once daily dosed carbapenems is described. Many of the prodrugs prepared for evaluation are rapidly hydrolyzed in rat plasma. Only bis-(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl (medoxomil) ester prodrug was rapidly hydrolyzed in most of the plasmas including rat, human, dog, and monkey. Although the rate of conversion of ertapenem diethyl ester prodrug (6) was slow in in vitro plasma hydrolysis, it showed the best in vivo pharmacokinetic profile in dog by an intraduodenal dosing giving >31% total oral absorption.

[Microbiology of diabetic foot infections: role of ertapenem]

Many patients with diabetes develop foot ulcers that are very susceptible to infections which may place the patients at risk for lower-limb amputation. Such infections require adequate management with antibiotics. The authors performed a systematic analysis and critical review of studies with the dual aim of assessing bacterial profiles and antimicrobial susceptibility patterns in patients with diabetic foot infections using various methods for sample collection and evaluating the safety and efficacy of ertapenem as initial empirical treatment for such infections. Following a selection of only studies with adequate description of methods for pathogen isolation and antibiogram determination, nine studies were included. The need for adequate prospective multicenter studies to assess the value of empirical antibiotic regimens for diabetic foot became evident and the conclusions were as follows: proper identification of causative agents, appropriate antibiotic therapy and management of complications in these infections are essential to achieve a successful outcome; the sampling procedure is extremely important in the evaluation of the microbial flora of the foot ulcer; susceptibility testing should be performed routinely at least for those species with unpredictable resistance; and ertapenem has been shown to be useful in the treatment of a wide range of moderate-to-severe lower extremity infections in a broad spectrum of patients.

Fluoroquinolone resistance among gram-negative urinary tract pathogens: global smart program results, 2009-2010

OBJECTIVES

To determine the rates of fluoroquinolone resistant (FQR) in gram-negative bacilli urinary tract infections (UTIs) in a global population.

METHODS

The Study for Monitoring Antimicrobial Resistance Trends (SMART) collected 1,116 FQR gram-negative urinary pathogens from hospitalized patients in 33 countries during 2009-2010. Amikacin, ertapenem, and imipenem were the most active agents tested against FQR UTI pathogens, including extended-spectrum beta-lactamase producers.

RESULTS

FQR rates vary widely country to country with a range of 6% to 75%. Regional FQR rates were 23.5% in North America, 29.4% in Europe, 33.2% in Asia, 38.7% in Latin America, and 25.5% in the South Pacific.

CONCLUSIONS

These observations suggest that fluoroquinolones may no longer be effective as first-line therapy for gram-negative UTI in hospitalized patients.

Comparison of ertapenem and ceftriaxone therapy for acute pyelonephritis and other complicated urinary tract infections in Korean adults: a randomized, double-blind, multicenter trial

The efficacy and safety of ertapenem, 1 g once daily, were compared with that of ceftriaxone, 2 g once daily, for the treatment of adults with acute pyelonephritis (APN) and complicated urinary tract infections (cUTIs) in a prospective, multicenter, double-blinded, randomized study. After ≥ 3 days of parenteral study therapy, patients could be switched to an oral agent. Of 271 patients who were initially stratified by APN (n = 210) or other cUTIs (n = 61), 66 (48.9%) in the ertapenem group and 71 (52.2%) in the ceftriaxone group were microbiologically evaluable. The mean duration of parenteral and total therapy, respectively, was 5.6 and 13.8 days for ertapenem and 5.8 and 13.8 days for ceftriaxone. The most common pathogen was Escherichia coli. At the primary efficacy endpoint 5-9 days after treatment, 58 (87.9%) patients in the ertapenem group and 63 (88.7%) in the ceftriaxone had a favorable microbiological response. When compared by stratum and severity, the outcomes in the two groups were equivalent. The frequency and severity of drug-related adverse events were generally similar in both treatment groups. The results indicate that ertapenem is highly effective and safe for the treatment of APN and cUTIs.