Comparison of BD Phoenix and disk diffusion to broth microdilution for determining cefepime susceptibility among carbapenem-resistant Enterobacterales.

There are increasing reports of carbapenem-resistant Enterobacterales (CRE) that test as cefepime-susceptible (S) or susceptible-dose dependent (SDD). However, there are no data to compare the cefepime testing performance of BD Phoenix automated susceptibility system (BD Phoenix) and disk diffusion (DD) relative to reference broth microdilution (BMD) against carbapenemase-producing (CPblaKPC-CRE) and non-producing (non-CP CRE) isolates. Cefepime susceptibility results were interpreted according to CLSI M100Ed32. Essential agreement (EA), categorical agreement (CA), minor errors (miEs), major errors (MEs), and very major errors (VMEs) were calculated for BD Phoenix (NMIC-306 Gram-negative panel) and DD relative to BMD. Correlates were also analyzed by the error rate-bounded method. EA and CA for CPblaKPC-CRE isolates (n = 64) were <90% with BD Phoenix while among non-CP CRE isolates (n = 58), EA and CA were 96.6%, and 79.3%, respectively. CA was <90% with DD for both cohorts. No ME or VME was observed for either isolate cohort; however, miEs were >10% for CPblaKPC-CRE and non-CP CRE with BD Phoenix and DD tests. For error rate-bounded method, miEs were <40% for IHigh + 1 to ILow - 1 ranges for CPblaKPC-CRE and non-CP CRE with BD Phoenix. Regarding disk diffusion, miEs were unacceptable for all MIC ranges among CPblaKPC-CRE. For non-CP CRE isolates, only IHigh + 1 to ILow - 1 range was acceptable at 37.2%. Using this challenge set of genotypic-phenotypic discordant CRE, the BD Phoenix MICs and DD susceptibility results trended higher (toward SDD and resistant phenotypes) relative to reference BMD results yielding lower CA. These results were more prominent among CPblaKPC-CRE than non-CP CRE.

Assessing the impact of meropenem exposure on ceftolozane/tazobactam-resistance development in Pseudomonas aeruginosa using in vitro serial passage.

BACKGROUND: Patients infected with difficult-to-treat Pseudomonas aeruginosa are likely to receive meropenem (MEM) empirically before escalation to ceftolozane/tazobactam (C/T). We assessed whether pre-exposure to MEM affected C/T resistance development on C/T exposure. MATERIALS AND METHODS: Nine clinical P. aeruginosa isolates were exposed to MEM 16 mg/L for 72 h. Then, isolates were serially passaged in the presence of C/T (concentration of 10 mg/L) for 72 h as two groups: an MEM-exposed group inoculated with MEM pre-exposed isolates and a non-MEM control group. At 24 h intervals, samples were plated on drug-free and drug-containing agar (C/T concentration 16/8 mg/L) and incubated to quantify bacterial densities (log10 cfu/mL). Growth on C/T agar indicated resistance development, and resistant population was calculated by dividing the cfu/mL on C/T plates by the cfu/mL on drug-free agar. RESULTS: At 72 h, resistant populations were detected in 6/9 isolates. In five isolates, MEM exposure significantly increased the prevalence of ceftolozane/tazobactam-resistance development; the percentages of resistance population were 100%, 100%, 53.5%, 31% and 3% for the MEM-exposed versus 0%, 0%, 2%, 0.35% and ≤0.0003% in the unexposed groups. One isolate had a similar resistant population at 72 h between the two groups. The remaining isolates showed no development of resistance, regardless of previous MEM exposure. CONCLUSIONS: MEM exposure may pre-dispose to C/T resistance development and thus limit the therapeutic utility of this ß-lactam/ß-lactamase inhibitor. Resistance may be a result of stress exposure or molecular-level mutations conferring cross-resistance. Further in vivo studies are needed to assess clinical implications of these findings.

Differential frequency of persister cells in clinically derived isolates of Pseudomonas aeruginosa after exposure to cefiderocol and ceftolozane/tazobactam.

BACKGROUND: Bacterial persistence is a phenomenon whereby a subpopulation of bacteria survive high concentrations of an active antibiotic in the absence of phenotypic alterations. Persisters are associated with chronic and recurrent infections for pathogens including Pseudomonas aeruginosa. Understanding persister profiles of newer antibiotics such as cefiderocol and ceftolozane/tazobactam against P. aeruginosa is warranted as these agents generally target difficult-to-treat infections. METHODS: Persister formation was assessed using in vitro assays against nine clinical P. aeruginosa isolates exposed to cefiderocol or ceftolozane/tazobactam. Quantitative persister assays were performed using a stationary phase of bacteria challenged with 10-fold MIC drug concentrations. Persisters were quantitated as the percent persisters at 24 h and the log ratio (LR) difference in AUC for cfu for each antibiotic alone compared with growth control. The tolerance disc test (TDtest) was used to qualitatively detect persisters. RESULTS: Percent persisters at 24 h was lower with cefiderocol compared with ceftolozane/tazobactam for six of the nine tested isolates. Eight of the nine isolates had higher reduction in LR for cefiderocol groups, suggesting an overall higher and more rapid bacterial reduction in cefiderocol groups. For cefiderocol, five of the nine tested isolates lacked regrowth after replacement with glucose disc, suggesting no persistence via the TDtest. For ceftolozane/tazobactam, three isolates lacked persister formation. CONCLUSIONS: Cefiderocol resulted in less bacterial persistence relative to ceftolozane/tazobactam against nine clinical P. aeruginosa isolates. Cefiderocol's siderophore mechanism may be advantageous over ceftolozane/tazobactam through enhanced anti-persister effects. Clinical correlation of these findings is warranted as persisters can lead to antibiotic resistance and treatment failure.

In vitro synergy of the combination of sulbactam-durlobactam and cefepime at clinically relevant concentrations against A. baumannii, P. aeruginosa and Enterobacterales.

BACKGROUND: Sulbactam-durlobactam is a potent combination active against Acinetobacter baumannii; however, it lacks activity against other nosocomial pathogens. Cefepime is a common first-line therapy for hospital/ventilator-associated pneumonia caused by Gram-negative pathogens including Pseudomonas aeruginosa and Enterobacterales. With increasing resistance to cefepime, and the significant proportion of polymicrobial nosocomial infections, effective therapy for infections caused by Acinetobacter baumannii, P. aeruginosa and Enterobacterales is needed. This study investigated the in vitro synergy of sulbactam-durlobactam plus cefepime against relevant pathogens. METHODS: Static time-kills assays were performed in duplicate against 14 cefepime-resistant isolates (A. baumannii, n = 4; P. aeruginosa, n = 4; Escherichia coli, n = 3; Klebsiella pneumoniae, n = 3). One WT K. pneumoniae isolate was included. Antibiotic concentrations simulated the free-steady state average concentration of clinically administered doses in patients. RESULTS: Sulbactam-durlobactam alone showed significant activity against A. baumannii consistent with the MIC values. Sulbactam-durlobactam plus cefepime showed synergy against one A. baumannii isolate with an elevated MIC to sulbactam-durlobactam (32 mg/L). Against all P. aeruginosa isolates, synergy was observed with sulbactam-durlobactam plus cefepime. For the Enterobacterales, one E. coli isolate demonstrated synergy while the others were indifferent due to significant kill from sulbactam-durlobactam alone. The combination of sulbactam-durlobactam plus cefepime showed synergy against one of the K. pneumoniae and additive effects against the other two K. pneumoniae tested. No antagonism was observed in any isolates including the WT strain. CONCLUSIONS: Synergy and no antagonism was observed with a combination of sulbactam-durlobactam and cefepime; further in vivo pharmacokinetic/pharmacodynamics data and clinical correlation are necessary to support our findings.

Cefepime in vivo activity against carbapenem-resistant Enterobacterales that test as cefepime susceptible or susceptible-dose dependent in vitro: implications for clinical microbiology laboratory and clinicians.

BACKGROUND: Carbapenem-resistant Enterobacterales (CRE) are a public health concern. Among these isolates, there are reports of isolates that test as cefepime susceptible or susceptible-dose dependent (SDD) in vitro despite presence of a carbapenemase. This study aimed to evaluate the pharmacokinetic/pharmacodynamic profile of cefepime against carbapenemase-producing (CP-CRE) and non-producing (non-CP-CRE) isolates with a range of cefepime MICs. METHODS: Reference broth microdilution and modified carbapenem inactivation method (mCIM) were performed on genotypically characterized clinical CRE isolates. Ultimately, CP-CRE (n = 21; blaKPC) and non-CP-CRE (n = 19) isolates with a distribution of cefepime MICs (≤0.5 to >256 mg/L) were utilized in the murine thigh infection model. Mice were treated with cefepime human-simulated regimens (HSRs) representative of a standard dose (1 g q12h 0.5 h infusion) or the SDD dose (2 g q8h 0.5 h infusion). Efficacy was assessed as the change in bacterial growth at 24 h compared with 0 h control, where ≥1 log bacterial reduction is considered translational value for clinical efficacy. RESULTS: Among both cohorts of CRE isolates, i.e. CP-CRE and non-CP-CRE, that tested as SDD to cefepime in vitro, 1 log bacterial reduction was not attainable with cefepime. Further blunting of cefepime efficacy was observed among CP-CRE isolates compared with non-CP-CRE across both susceptible and SDD categories. CONCLUSIONS: Data indicate to avoid cefepime for the treatment of serious infections caused by CRE isolates that test as cefepime susceptible or SDD. Data also provide evidence that isolates with the same antibiotic MIC may have different pharmacokinetic/pharmacodynamic profiles due to their antimicrobial resistance mechanism.

Relative bioavailability of crushed tebipenem administered through a nasogastric tube with and without enteral feeding.

OBJECTIVE: Tebipenem pivoxil hydrobromide is an orally bioavailable carbapenem prodrug of the active agent tebipenem with broad-spectrum activity against drug-resistant Enterobacterales. This study aimed to evaluate the relative bioavailability of crushed tebipenem tablets administered via nasogastric tube (NGT) with or without concomitant enteral feeds. METHODS: This Phase 1, open label study randomized 12 healthy subjects to receive a crushed tebipenem tablet via NGT (n = 6) or via NGT with concomitant Osmolite® enteral feeds (n = 6) on Study Day 1, followed by oral administration of tebipenem whole tablet (reference formulation) on Study Day 2. Tebipenem plasma concentrations were measured by LC with mass spectrometry. Bioequivalence was determined using pharmacokinetic parameters derived through non-compartmental analyses. RESULTS: Mean ±â€ŠSD tebipenem pharmacokinetic parameters in plasma for subjects who received a crushed tablet via NGT (relative to whole tablet) and a crushed tablet with enteral feeds (relative to whole tablet) were as follows: maximum total plasma concentration (Cmax), 11.1 ±â€Š3.9 (12 ±â€Š3.4) and 10.2 ±â€Š1.9 (10 ±â€Š4) mg/L; area under the curve (AUC0-8), 17.5 ±â€Š3.5 (17.9 ±â€Š2.3) and 15 ±â€Š4.3 (13.4 ±â€Š5.3) mg•h/L. Using the 90% CI criteria, Cmaxand AUC0-8 values for tebipenem were found to be bioequivalent following alternative methods of administration compared with oral dosing of the whole tablet. The three methods of administration were well tolerated. CONCLUSION: Results demonstrate that tebipenem maintained bioequivalence when crushed and administered via NGT with and without accompanying enteral feeds in healthy subjects, relative to whole tablet oral administration. Data therefore support alternative methods of tebipenem administration depending on patient condition.

Protective Effect of TRPM8 against Indomethacin-Induced Small Intestinal Injury via the Release of Calcitonin Gene-Related Peptide in Mice.

Transient receptor potential melastatin 8 (TRPM8) is a non-selective cation channel activated by mild cooling and chemical agents including menthol. Nonsteroidal anti-inflammatory drugs have antipyretic, analgesic effects, and they can cause stomach and small intestinal injury. The current study investigated the role of TRPM8 in the pathogenesis of indomethacin-induced small intestinal injury. In male TRPM8-deficient (TRPM8KO) and wild-type (WT) mice, intestinal injury was induced via the subcutaneous administration of indomethacin. In addition, the effect of WS-12, a specific TRPM8 agonist, was examined in TRPM8KO and WT mice with indomethacin-induced intestinal injury. TRPM8KO mice had a significantly higher intestinal ulcerogenic response to indomethacin than WT mice. The repeated administration of WS-12 significantly attenuated the severity of intestinal injury in WT mice. However, this response was abrogated in TRPM8KO mice. Furthermore, in TRPM8-enhanced green fluorescent protein (EGFP) transgenic mice, which express EGFP under the direction of TRPM8 promoter, the EGFP signals in the indomethacin-treated intestinal mucosa were upregulated. Further, the EGFP signals were commonly found in calcitonin gene-related peptide (CGRP)-positive sensory afferent neurons and partly colocalized with substance P (SP)-positive neurons in the small intestine. The intestinal CGRP-positive neurons were significantly upregulated after the administration of indomethacin in WT mice. Nevertheless, this response was abrogated in TRPM8KO mice. In contrast, indomethacin increased the expression of intestinal SP-positive neurons in not only WT mice but also TRPM8KO mice. Thus, TRPM8 has a protective effect against indomethacin-induced small intestinal injury. This response may be mediated by the upregulation of CGRP, rather than SP.

Effect of Blood Product Resuscitation on Cefazolin Pharmacokinetics in Trauma Patients.

Background: Antibiotics are frequently administered prophylactically to trauma patients with various injury patterns to prevent infectious complications. Trauma patients may also require large volume resuscitation with blood products. Limited data are available to support antibiotic dosing recommendations in this population. We hypothesized that we would be able to develop a population pharmacokinetic model of cefazolin, a frequently used antibiotic in the trauma scenario, from remnant blood samples by pharmacokinetic analysis of trauma patients. Methods: Remnant plasma from standard of care chemistry/hematology assessments was retrieved within 48 h of collection and assayed to determine cefazolin concentrations. Population pharmacokinetic analyses were conducted in Pmetrics using R. Linear regression was conducted to assess the effect of blood product resuscitation volume on cefazolin pharmacokinetic parameters. Results: Cefazolin concentrations best fitted a two-compartment model (Akaike information criterion: 443.9). The mean ± standard deviation parameters were total body clearance (4.3 ± 1.9L), volume of the central compartment (Vc: 7.7 ± 6.9L), and intercompartment transfer constants (k12: 1.3 ± 0.98 h-1, k21: 0.6 ± 0.45 h-1). No statistical relationships were observed between blood products, volume of blood products, and cefazolin clearance or Vc (R2: 0.0004-0.21, p = 0.08-0.95). Using a 5,000-patient Monte Carlo simulation, 2 g with repeated dosing every 2 h until end of surgery was required to achieve 93.2% probability of 100% free time above the minimum inhibitory concentration (MIC) (fT > MIC) at the ECOFF value for Staphylococcus aureus (2 mg/L). Conclusions: In these 15 trauma patients receiving blood transfusion, no relationship with blood volume resuscitation and cefazolin pharmacokinetics was observed. On the basis of this pharmacokinetic model, frequent cefazolin doses are required to maintain 100% fT > MIC.

Physical compatibility of sulbactam/durlobactam with select intravenous drugs during simulated Y-site administration.

PURPOSE: Sulbactam/durlobactam is a combination antibiotic designed to target Acinetobacter baumannii, including carbapenem-resistant and multidrug-resistant strains. The objective of this study was to determine the physical compatibility of sulbactam/durlobactam solution during simulated Y-site administration with 95 intravenous (IV) drugs. METHODS: Vials of sulbactam/durlobactam solution were diluted in 0.9% sodium chloride injection to a volume of 100 mL (the final concentration of both drugs was 15 mg/mL). All other IV drugs were reconstituted according to the manufacturer's recommendations and diluted with 0.9% sodium chloride injection to the upper range of concentrations used clinically or tested undiluted as intended for administration. Y-site conditions were simulated by mixing 5 mL of sulbactam/durlobactam with 5 mL of the tested drug solutions in a 1:1 ratio. Solutions were inspected for physical characteristics (clarity, color, and Tyndall effect), turbidity, and pH changes before admixture, immediately post admixture, and over 4 hours. Incompatibility was defined as any observed precipitation, significant color change, positive Tyndall test, or turbidity change of ≥0.5 nephelometric turbidity unit during the observation period. RESULTS: Sulbactam/durlobactam was physically compatible with 38 out of 42 antimicrobials tested (90.5%) and compatible overall with 86 of 95 drugs tested (90.5%). Incompatibility was observed with albumin, amiodarone hydrochloride, ceftaroline fosamil, ciprofloxacin, daptomycin, levofloxacin, phenytoin sodium, vecuronium, and propofol. CONCLUSION: The Y-site compatibility of sulbactam/durlobactam with 95 IV drugs was described. These compatibility data will assist pharmacists and nurses to safely coordinate administration of IV medications with sulbactam/durlobactam.

Validation of Cefiderocol Package Insert Dosing Recommendation for Patients Receiving Continuous Renal Replacement Therapy: A Prospective Multicenter Pharmacokinetic Study.

Background: Cefiderocol is the first antibiotic with effluent flow rate-based dosing recommendations outlined in the product label for patients receiving continuous renal replacement therapy (CRRT). We aimed to investigate the population pharmacokinetics of cefiderocol among patients receiving CRRT and validate these dosing recommendations. Methods: A multicenter, prospective cefiderocol pharmacokinetic study among intensive care unit patients receiving CRRT was conducted (2022-2023). Blood sampling was performed at steady-state and cefiderocol concentrations were assayed by validated liquid chromatography-tandem mass spectrometry. Population pharmacokinetic analyses were conducted in Pmetrics using R software. The free time above the minimum inhibitory concentration (f T > MIC) and total daily area under the concentration time curve (AUCdaily) were calculated. Results: Fourteen patients with effluent flow rates ranging from 2.1 to 5.1 L/h were enrolled. Cefiderocol concentrations best fitted a 2-compartment model. Mean ± standard deviation (SD) parameter estimates for clearance, central compartment volume, and intercompartment transfer constants (k12 and k21) were 3.5 ± 1.5 L/hour, 10.7 ± 8.4 L, 3.9 ± 1.8 hours-1, and 2.2 ± 2.2 hours-1, respectively. With simulations based on product label dosing recommendations, all patients achieved 100% fT > MIC up to MIC 8 mg/L with an AUCdaily (mean ± SD) of 1444 ± 423 mg × hour/L. Cefiderocol was well tolerated among the 14 patients. Conclusions: The current package insert dosing recommendations resulted in pharmacodynamically optimized cefiderocol exposures. Cefiderocol concentrations exceeded relevant MIC breakpoints in all patients at each effluent flow rate, and AUCdaily was within the range observed in patients in the phase 3 clinical trials, suggestive of a safe and therapeutic drug profile.

3D-Printed Microfluidics Potential in Combating Future and Current Pandemics (COVID-19).

Coronavirus disease (COVID-19) emerged in China in December 2019. In March 2020, the WHO declared it a pandemic leading to worldwide lockdowns and travel restrictions. By May, it infected 4,789,205 and killed 318,789 people. This led to severe shortages in the medical sector besides devastating socio-economic effects. Many technologies such as artificial intelligence (AI), virtual reality (VR), microfluidics, 3D printing, and 3D scanning can step into contain the virus and hinder its extensive spread. This article aims to explore the potentials of 3D printing and microfluidic in accelerating the diagnosis and monitoring of the disease and fulfilling the shortages of personal protective equipment (PPE) and medical equipment. It highlights the main applications of 3D printers and microfluidics in providing PPE (masks, respirators, face shields, goggles, and isolation chambers/hoods), supportive care (respiratory equipment) and diagnostic supplies (sampling swabs & lab-on-chip) to ease the COVID-19 pressures. Also, the cost of such technology and regulation considerations are addressed. We conclude that 3D printing provided reusable and low-cost solutions to mitigate the shortages. However, safety, sterility, and compatibility with environmental protection standards need to be guaranteed through standardization and assessment by regulatory bodies. Finally, lessons learned from this pandemic can also help the world prepare for upcoming outbreaks.