Ampicillin-Sulbactam for Carbapenem-Susceptible Acinetobacter baumannii Pneumonia: A Case for High-Dose, Continuous Infusion Dosing Strategy in the Trauma ICU.

Background: The optimal ampicillin-sulbactam dosing regimen for carbapenem-susceptible Acinetobacter baumannii isolates in critically ill trauma patients has not been clearly defined. One strategy to provide the adequate sulbactam dose includes high-dose continuous infusion. Case(s) Description: We present three cases of critically ill trauma patients with augmented renal clearance treated with high-dose ampicillin-sulbactam through an intravenous continuous infusion for ventilator-associated pneumonia. All A. baumannii isolates were susceptible to sulbactam with low minimum inhibitory concentrations. All achieved clinical cure at the end of therapy and no recurrent pneumonia was noted. No clinically substantial adverse effect attributable to ampicillin-sulbactam therapy occurred. Discussion: There is limited evidence to endorse high-dose, continuous infusion ampicillin-sulbactam for treatment of infections caused by carbapenem-susceptible A. baumannii. This report presents three critically ill trauma patients with augmented renal clearance that achieved positive clinical outcomes with higher doses of ampicillin-sulbactam administered through a continuous infusion.

A systematic review of the pharmacokinetics and pharmacodynamics of novel beta-lactams and beta-lactam with beta-lactamase inhibitor combinations for the treatment of pneumonia caused by carbapenem-resistant Gram-negative bacteria.

BACKGROUND: Novel beta-lactams show activity against many multidrug-resistant Gram-negative bacteria that cause severe lung infections. Understanding pharmacokinetic/pharmacodynamic characteristics of these agents may help optimise outcomes in the treatment of pneumonia. OBJECTIVES: To describe and appraise studies that report pulmonary pharmacokinetic and pharmacodynamic data of cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam and meropenem/vaborbactam. METHODS: MEDLINE (PubMed), Embase, Web of Science and Scopus libraries were used for the literature search. Pulmonary population pharmacokinetic and pharmacokinetic/ pharmacodynamic studies on adult patients receiving cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam, and meropenem/vaborbactam published in peer-reviewed journals were included. Two independent authors screened, reviewed, and extracted data from included articles. A reporting guideline for clinical pharmacokinetic studies (ClinPK statement) was used for bias assessment. Relevant outcomes were included, such as population pharmacokinetic parameters and probability of target attainment of dosing regimens. RESULTS: Twenty-four articles were included. There was heterogeneity in study methods and reporting of results, with diversity across studies in adhering to the ClinPK statement checklist. Ceftolozane/tazobactam was the most studied agent. Only two studies collected epithelial lining fluid samples from patients with pneumonia. All the other phase I studies enrolled healthy subjects. Significant population heterogeneity was evident among available population pharmacokinetic models. Probabilities of target attainment rates above 90% using current licensed dosing regiments were reported in most studies. CONCLUSIONS: Although lung pharmacokinetics was rarely described, this review observed high target attainment using plasma pharmacokinetic data for all novel beta-lactams. Future studies should describe lung pharmacokinetics in patient populations at risk of carbapenem-resistant pathogen infections.

Piperacillin-Tazobactam versus Cefotaxime as Empiric Treatment for Febrile Urinary Tract Infection in Hospitalized Children.

BACKGROUND: According to international pediatric urinary tract infection (UTI) guidelines, selecting ampicillin/sulbactam or amoxicillin/clavulanate is recommended as the first-line treatment for pediatric UTI. In Korea, elevated resistance to ampicillin and ampicillin/sulbactam has resulted in the widespread use of third-generation cephalosporins for treating pediatric UTIs. This study aims to compare the efficacy of piperacillin-tazobactam (TZP) and cefotaxime (CTX) as first-line treatments in hospitalized children with UTIs. MATERIALS AND METHODS: The study, conducted at Jeju National University Hospital, retrospectively analyzed medical records of children hospitalized for febrile UTIs between 2014 and 2017. UTI diagnosis included unexplained fever, abnormal urinalysis, and the presence of significant uropathogens. Treatment responses, recurrence, and antimicrobial susceptibility were assessed. RESULTS: Out of 323 patients, 220 met the inclusion criteria. Demographics and clinical characteristics were similar between TZP and CTX groups. For children aged ≥3 months, no significant differences were found in treatment responses and recurrence. Extended-spectrum beta-lactamase (ESBL)-positive strains were associated with recurrence in those <3 months. CONCLUSION: In Korea, escalating resistance to empirical antibiotics has led to the adoption of broad-spectrum empirical treatment. TZP emerged as a viable alternative to CTX for hospitalized children aged ≥3 months with UTIs. Consideration of ESBL-positive strains and individualized approaches for those <3 months are crucial.

Delabelling beta-lactam allergy.

Background: Hypersensitivity to beta-lactam (BL) antibiotics is one of the most frequent reported drug allergies. In our population, it is common to find labels of BL allergy in electronic medical records (EMRs) that have not been assessed. The objective of our study was to detect patients with beta-lactam allergy labels in their EMRs and to assess how many of them are false after a correct diagnostic evaluation. Methods: A multicentre prospective study was performed with patients labelled as allergic to BLs in their EMRs in the previous 5 years. Demographical and clinical data, as well as variables regarding the BL allergy label and the characteristics of the index reaction from clinical history and EMRs, were recorded. Then, diagnostic assessments including clinical history, skin tests (STs), and drug provocation tests (DPTs) were conducted in order to confirm or exclude the diagnosis of BL allergy. Results: A total of 249 patients completed the study, of which 160 (64.3%) were women with a median age of 57 years (interquartile range [IQR], 45-68). The most frequent BL allergy labels detected were for penicillin (124), amoxicillin/clavulanic acid (61), and amoxicillin (54). Of the 204 patients who underwent STs, 20.1% were positive. DPTs were performed in 224 patients, showing good tolerance in 87.1% of cases. After the allergy diagnosis work-up, 186 patients (74.7%) were diagnosed as non-allergic to BL antibiotics. Conclusion: In our study population, the number of patients labelled as allergic to BLs in their EMRs was similar to that in previously published studies, with proportions near to 75%-80% being falsely labelled as allergic to BLs.

Towards pharmacokinetic boosting of phenoxymethylpenicillin (penicillin-V) using probenecid for the treatment of bacterial infections.

In the face of increasing antimicrobial tolerance and resistance there is a global obligation to optimise oral antimicrobial dosing strategies including narrow spectrum penicillins, such as penicillin-V. We conducted a randomised, crossover study in healthy volunteers to characterise the influence of probenecid on penicillin-V pharmacokinetics and estimate the pharmacodynamics against Streptococcus pneumoniae. Twenty participants took six doses of penicillin-V (250 mg, 500 mg or 750 mg four times daily) with and without probenecid. Total and free concentrations of penicillin-V and probenecid were measured at two timepoints. A pharmacokinetic model was developed, and the probability of target attainment (PTA) calculated. The mean difference (95% CI) between penicillin-V alone and in combination with probenecid for serum total and free penicillin-V concentrations was significantly different at both timepoints (total: 45 min 4.32 (3.20-5.32) mg/L p < 0.001, 180 min 2.2 (1.58-3.25) mg/L p < 0.001; free: 45 min 1.15 (0.88-1.42) mg/L p < 0.001, 180 min 0.5 (0.35-0.76) mg/L p < 0.001). There was no difference between the timepoints in probenecid concentrations. PTA analysis shows probenecid allows a fourfold increase in MIC cover. Addition of probenecid was safe and well tolerated. The data support further research into improved dosing structures for complex outpatient therapy and might also be used to address penicillin supply shortages.

A comparison of antibiotic resistance genes and mobile genetic elements in wild and captive Himalayan vultures.

As the most widely distributed scavenger birds on the Qinghai-Tibetan Plateau, Himalayan vultures (Gyps himalayensis) feed on the carcasses of various wild and domestic animals, facing the dual selection pressure of pathogens and antibiotics and are suitable biological sentinel species for monitoring antibiotic resistance genes (ARGs). This study used metagenomic sequencing to comparatively investigate the ARGs and mobile genetic elements (MGEs) of wild and captive Himalayan vultures. Overall, the resistome of Himalayan vultures contained 414 ARG subtypes resistant to 20 ARG types, with abundances ranging from 0.01 to 1,493.60 ppm. The most abundant resistance type was beta-lactam (175 subtypes), followed by multidrug resistance genes with 68 subtypes. Decreases in the abundance of macrolide-lincosamide-streptogramin (MLS) resistance genes were observed in the wild group compared with the zoo group. A total of 75 genera (five phyla) of bacteria were predicted to be the hosts of ARGs in Himalayan vultures, and the clinical (102 ARGs) and high-risk ARGs (35 Rank I and 56 Rank II ARGs) were also analyzed. Among these ARGs, twenty-two clinical ARGs, nine Rank I ARG subtypes, sixteen Rank II ARG subtypes were found to differ significantly between the two groups. Five types of MGEs (128 subtypes) were found in Himalayan vultures. Plasmids (62 subtypes) and transposases (44 subtypes) were found to be the main MGE types. Efflux pump and antibiotic deactivation were the main resistance mechanisms of ARGs in Himalayan vultures. Decreases in the abundance of cellular protection were identified in wild Himalayan vultures compared with the captive Himalayan vultures. Procrustes analysis and the co-occurrence networks analysis revealed different patterns of correlations among gut microbes, ARGs, and MGEs in wild and captive Himalayan vultures. This study is the first step in describing the characterization of the ARGs in the gut of Himalayan vultures and highlights the need to pay more attention to scavenging birds.

An enantioselective formal synthesis of thienamycin.

Thienamycin is a carbapenem antibiotic with potent activity against gram-negative and gram-positive bacteria. Due to its promising activity but lack of chemical stability, thienamycin serves as inspiration for new synthetic antibiotic scaffolds. In this study, we report a nine-step enantioselective formal synthesis of thienamycin. Our route utilizes an asymmetric reduction, enabled by NaBH4 and D-tartaric acid, followed by a series of diastereoselective reactions to access the key azetidinone precursor to thienamycin. This azetidinone precursor could be used as an intermediate to further develop and expand the scope of next-generation beta-lactam antibiotic scaffolds.

Detection of antibiotic resistant Enterobacterales in commercial raw pet food: a preliminary study.

Introduction: Raw diets have become popular in companion animal nutrition, but these diets may be contaminated with harmful bacteria because heat processing is not utilized to mitigate pathogens during the production process. We analyzed 24 commercially available frozen raw canine and feline diets for extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E). Methods: Samples were incubated in tryptic soy broth augmented with 50 µg/mL ampicillin to enrich for ESBL-E. ESBL-E were isolated using CHROMagar ESBL plates and isolate identification and antibiotic susceptibility testing were confirmed using the VITEK®2 instrument. Results: ESBL-E were isolated from 42% (10/24) of raw diets, with E. coli, Enterobacter cloacae complex and Klebsiella pneumoniae predominating. Most ESBL-E isolates (71%, 32/45) were multidrug-resistant. Direct plating of samples onto tryptic soy agar yielded bacterial counts >6 log10 for 2 samples from two different manufacturers. Conclusion: This preliminary study justifies further investigation into the potential contribution of raw diets to the dissemination of antibiotic resistant bacteria in companion animals and domestic living spaces.

Evolution towards extremely high ß-lactam resistance in Mycobacterium abscessus outbreak strains.

Treatment of Mycobacterium abscessus pulmonary disease requires multiple antibiotics including intravenous ß-lactams (e.g., imipenem, meropenem). M. abscessus produces a ß-lactamase (BlaMab) that inactivates ß-lactam drugs but less efficiently carbapenems. Due to intrinsic and acquired resistance in M. abscessus and poor clinical outcomes, it is critical to understand the development of antibiotic resistance both within the host and in the setting of outbreaks. We compared serial longitudinally collected M. abscessus subsp. massiliense isolates from the index case of a CF center outbreak and four outbreak-related strains. We found strikingly high imipenem resistance in the later patient isolates, including the outbreak strain (MIC >512 µg/ml). The phenomenon was recapitulated upon exposure of intracellular bacteria to imipenem. Addition of the ß-lactamase inhibitor avibactam abrogated the resistant phenotype. Imipenem resistance was caused by an increase in ß-lactamase activity and increased bla Mab mRNA level. Concurrent increase in transcription of preceding ppiA gene indicated upregulation of the entire operon in the resistant strains. Deletion of the porin mspA coincided with the first increase in MIC (from 8 to 32 µg/ml). A frameshift mutation in msp2 responsible for the rough colony morphology, and a SNP in ATP-dependent helicase hrpA co-occurred with the second increase in MIC (from 32 to 256 µg/ml). Increased BlaMab expression and enzymatic activity may have been due to altered regulation of the ppiA-bla Mab operon by the mutated HrpA alone, or in combination with other genes described above. This work supports using carbapenem/ß-lactamase inhibitor combinations for treating M. abscessus, particularly imipenem resistant strains.

Implementation and outcomes of beta-lactam allergy management protocol at a comprehensive cancer center.

PURPOSE: Beta-lactam allergy (BLA) is associated with increased broad-spectrum antibiotic (Br-ABX) use and worse clinical outcomes. We evaluated our hospital-wide BLA protocol (BLA-P) that used following categories: intolerance, low-risk, and high-risk. METHODS: Hospitalized adult patients with listed BLA during 10/2021-12/2022 were eligible. Exclusions were critically ill, surgical, hospice or comfort care, or non-verbal patients. Assessment was counted each time a pharmacist evaluated BLA. Interventions were no further action (high-risk allergy, patient refusal, unstable clinical status), updated allergy label, or delabeled. Delabeling was done either based on antibiotic history (direct-delabeling), or via test-dose challenge for low-risk patients. Br-ABX usage was compared in the unique delabeled patients: the empiric antibiotic use 90 days post-delabeling versus pre-delabeling using McNemar test (SPSS). RESULTS: A total of 700 assessments in 631 patients were identified. 441 assessments in 377 patients (median 63 years-old, 41% male, 50% hematological cancer) met inclusion criteria. The assessments revealed 9% intolerance, 55% low-risk, 23% high-risk and 13% unknown reaction. Interventions resulted in no further action 7%, updated label 72%, and delabeling 21%. 65% of the delabeling was via direct-delabeling and 35% test-dose challenge. Among patients who received a test-dose challenge, 36/36(97%) had no documented allergic reactions, and 1/26(3%) developed a mild rash. The use of aztreonam (pre-delabeling 28% vs. post-delabeling 1.2%, p < 0.001) and meropenem (13% vs. 2.4%, p = 0.022) significantly decreased while cefepime (24% vs. 50%, p = 0.001) and piperacillin-tazobactam (3.7% vs. 22%, p < 0.001) increased after delabeling. CONCLUSION: BLA-P led to 21% delabeling, which resulted in increased preferred Br-ABX and decrease in aztreonam/meropenem use among delabeled patients.

Influence of ß-lactam pharmacodynamics on the systems microbiology of gram-positive and gram-negative polymicrobial communities.

Objectives: We sought to evaluate the pharmacodynamics of ß-lactam antibacterials against polymicrobial communities of clinically relevant gram-positive and gram-negative pathogens. Methods: Two Enterococcus faecalis isolates, two Staphylococcus aureus isolates, and three Escherichia coli isolates with varying ß-lactamase production were evaluated in static time-killing experiments. Each gram-positive isolate was exposed to a concentration array of ampicillin (E. faecalis) or cefazolin (S. aureus) alone and during co-culture with an E. coli isolate that was ß-lactamase-deficient, produced TEM-1, or produced KPC-3/TEM-1B. The results of the time-killing experiments were summarized using an integrated pharmacokinetic/pharmacodynamics analysis as well as mathematical modelling to fully characterize the antibacterial pharmacodynamics. Results: In the integrated analysis, the maximum killing of ampicillin (Emax) against both E. faecalis isolates was ≥ 4.11 during monoculture experiments or co-culture with ß-lactamase-deficient E. coli, whereas the Emax was reduced to ≤ 1.54 during co-culture with ß-lactamase-producing E. coli. In comparison to monoculture experiments, culturing S. aureus with KPC-producing E. coli resulted in reductions of the cefazolin Emax from 3.25 and 3.71 down to 2.02 and 2.98, respectively. Two mathematical models were created to describe the interactions between E. coli and either E. faecalis or S. aureus. When in co-culture with E. coli, S. aureus experienced a reduction in its cefazolin Kmax by 24.8% (23.1%RSE). Similarly, ß-lactamase-producing E. coli preferentially protected the ampicillin-resistant E. faecalis subpopulation, reducing Kmax,r by 90.1% (14%RSE). Discussion: ß-lactamase-producing E. coli were capable of protecting S. aureus and E. faecalis from exposure to ß-lactam antibacterials.

The Rising Tide of Antibiotic Resistance: A Study on Extended-Spectrum Beta-Lactamase and Carbapenem-Resistant Escherichia coli and Klebsiella pneumoniae.

BACKGROUND: The global spread of extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant Enterobacterales (CRE) poses a significant concern. Acquisition of antimicrobial resistance genes leads to resistance against several antibiotics, limiting treatment options. We aimed to study ESBL-producing and CRE transmission in clinical settings. METHODS: From clinical samples, 227 ESBL-producing and CRE isolates were obtained. The isolates were cultured on bacterial media and confirmed by VITEK 2. Antibiograms were tested against several antibiotics using VITEK 2. The acquired resistance genes were identified by PCR. RESULTS: Of the 227 clinical isolates, 145 (63.8%) were Klebsiella pneumoniae and 82 (36.1%) were Escherichia coli; 76 (33.4%) isolates were detected in urine, 57 (25.1%) in pus swabs, and 53 (23.3%) in blood samples. A total of 58 (70.7%) ESBL-producing E. coli were resistant to beta-lactams, except for carbapenems, and 17.2% were amikacin-resistant; 29.2% of E. coli isolates were resistant to carbapenems. A total of 106 (73.1%) ESBL-producing K. pneumoniae were resistant to all beta-lactams, except for carbapenems, and 66.9% to ciprofloxacin; 38 (26.2%) K. pneumoniae were resistant to carbapenems. Colistin emerged as the most effective antibiotic against both bacterial types. Twelve (20.6%) E. coli isolates were positive for blaCTX-M, 11 (18.9%) for blaTEM, and 8 (33.3%) for blaNDM. Forty-six (52.3%) K. pneumoniae isolates had blaCTX-M, 27 (18.6%) blaTEM, and 26 (68.4%) blaNDM. CONCLUSION: This study found a high prevalence of drug-resistant ESBL-producing and CRE, highlighting the need for targeted antibiotic use to combat resistance.

Meropenem/Vaborbactam-A Mechanistic Review for Insight into Future Development of Combinational Therapies.

Beta-lactam antibiotics have been a major climacteric in medicine for being the first bactericidal compound available for clinical use. They have continually been prescribed since their development in the 1940s, and their application has saved an immeasurable number of lives. With such immense use, the rise in antibiotic resistance has truncated the clinical efficacy of these compounds. Nevertheless, the synergism of combinational antibiotic therapy has allowed these drugs to burgeon once again. Here, the development of meropenem with vaborbactam-a recently FDA-approved beta-lactam combinational therapy-is reviewed in terms of structure rationale, activity gamut, pharmacodynamic/pharmacokinetic properties, and toxicity to provide insight into the future development of analogous therapies.

Preventing New Gram-negative Resistance Through Beta-lactam De-escalation in Hospitalized Patients With Sepsis: A Retrospective Cohort Study.

BACKGROUND: Whether antibiotic de-escalation reduces the risk of subsequent antibiotic resistance is uncertain. We sought to determine if beta-lactam (BL) antibiotic de-escalation is associated with decreased incidence of new Gram-negative resistance in hospitalized patients with sepsis. METHODS: In a retrospective cohort study, patients with sepsis who were treated with at least 3 consecutive days of BL antibiotics, the first 2 days of which were with a broad-spectrum BL agent defined as a spectrum score (SS) of ≥7 were enrolled. Patients were grouped into three categories: (1) de-escalation of beta-lactam spectrum score (BLSS), (2) no change in BLSS, or (3) escalation of BLSS. The primary outcome was the isolation of a new drug-resistant Gram-negative bacteria from a clinical culture within 60 days of cohort entry. Fine-Gray proportional hazards regression modeling while accounting for in-hospital death as a competing risk was performed. FINDINGS: Six hundred forty-four patients of 7742 (8.3%) patients developed new gram-negative resistance. The mean time to resistance was 23.7 days yielding an incidence rate of 1.85 (95% confidence interval [CI]: 1.71-2.00) per 1000 patient-days. The lowest incidence rate was observed in the de-escalated group 1.42 (95% CI: 1.16-1.68) per 1000 patient-days. Statistically significant reductions in the development of new gram-negative resistance were associated with BL de-escalation compared to no-change (hazards ratio (HR) 0.59 [95% CI: .48-.73]). CONCLUSIONS: De-escalation was associated with a decreased risk of new resistance development compared to no change. This represents the largest study to date showing the utility of de-escalation in the prevention of antimicrobial resistance.

[Penicillin allergy-Truth or duty?] / Penicillinallergie ­ Wahrheit oder Pflicht?

The beta-lactam antibiotics are some of the safest and best-tolerated antibiotic agents; however, many patients have reported allergies against penicillin. All beta-lactam antibiotics are only restrictively prescribed for these patients and alternative antibiotics are increasingly given, which carries the risk of negative clinical results and socioeconomic sequelae; however, over 95% of patients who reported an allergy to penicillin show a negative result in the allergy tests for penicillin and this antibiotic can safely be prescribed. The use of sensitive and specific instruments for identification of false penicillin allergies should be an important topic within the framework of antibiotic stewardship. Anesthesists can play a central role in the reduction of the enormous individual and public health burden associated with the classification of penicillin allergy by taking an appropriate medical history and a risk stratification for the identification of patients with a penicillin allergy. This overview article presents a possible delabelling algorithm within the framework of the clarification of a beta-lactam antibiotic allergy. The focus is on a structured allergy anamnesis using the penicillin allergy, five or fewer years ago, anaphylaxis/angioedema, severe cutaneous adverse reaction (SCAR) and treatment required for allergy episode (PEN-FAST) score.

Case Commentary: Dual ß-lactam as part of regimen to treat Mycobacterium abscessus lung disease.

Individuals with compromised lung function and immunity are susceptible to developing chronic Mycobacterium abscessus infection. Current treatment recommendations typically involve using one ß-lactam antibiotic in combination with non-ß-lactam antibiotics. However, a recent case study (B. Becken, K. M. Dousa, J. L. Johnson, S. M. Holland, and R. A. Bonomo, Antimicrob Agents Chemother 68:e00319-24, 2024, https://doi.org/10.1128/aac.00319-24) demonstrated successful treatment of chronic M. abscessus lung disease in a child using two ß-lactam antibiotics simultaneously. This commentary reviews the emerging evidence and outstanding questions regarding dual ß-lactam therapy for M. abscessus infections.

Management and Implications of Beta-Lactam Allergies.

Beta-lactam antibiotics are essential components in the current antimicrobial treatment strategy, playing a crucial role in ambulatory patients and hospitalized patients. Despite their prominent therapeutic index, the use of beta-lactam can lead to adverse effects, with allergic reactions being the most concerning because of their severity. Additionally, the phenomenon of cross-reactivity may occur among various beta-lactam families, with side chains significantly contributing to immunological recognition, making these structures often responsible for the cross-allergic reactivity of beta-lactams. Tools to assess beta-lactam allergy include taking a patient's medical history, performing skin tests, and conducting provocation tests. This research aims to analyze the relevant aspects related to the safe administration of beta-lactam antibiotics in hospitalized patients as well as provide knowledge on the proper management of patients with such hypersensitivity, by doing systemic research. This research was made using Google Scholar and keywords such as "Beta-lactam allergy," "Hypersensitivity," "Cross-reactivity," "Desensitization," and "Beta-lactam allergy management." In conclusion, substituting a beta-lactam antibiotic with an alternative antibiotic may not always be the best management option for these patients, as it may lead to more adverse effects, be less effective, and prolong hospitalization time. It may also result in higher rates of antibiotic-resistant infections and increased medical costs, as these alternatives are often more expensive. However, an alternative within the beta-lactam family can be sought by conducting the appropriate analyses. Although cross-reactivity does not always occur among all beta-lactams, potential cross-reactivity should always be considered.

Challenging dogmas: Intravenous versus oral beta-lactam antibiotic provocation tests.

Background: Drug provocation tests (DPT) are considered the gold standard procedure to ascertain the diagnosis of beta-lactam (BL) allergy. Regarding route of administration, current recommendations prioritize oral challenges, considering them safer, and reserving the intravenous route for drugs for which this is the only formulation. Objective: To compare in terms of tolerance and safety two protocols of BL DPT, using an oral protocol (OR-DPT) and an intravenous protocol (IV-DPT). Methods: A descriptive, retrospective study was performed, including adult patients who underwent IV-DPT or OR-DPT for suspected immediate or delayed hypersensitivity to BL antibiotics, over a period of 4 years (between January 2018 and December 2021). Demographical data, index hypersensivity reactions' characteristics and tolerance to DPT were reviewed. Results: A total of 1036 patients underwent DPT, mean age of 56.8 (standard deviation, SD, 17.8) years, 655 were women (63.2%). Immediate drug hypersensitivity reactions (DHR) had occurred in 564 of patients (54.4%). OR-DPT were performed in 439 (42.4%) and IV-DPT in 597 (57.6%). The frequency of reactions during DPT, regardless of the route used, was low (3.6%): only 16 (3.6%) in OR-DPT and 21 (3.5%) in IV-DPT. From IV-DPT, 16 out 21 DHR during DPT were immediate compared with 4 out of 16 in OR-DPT. Adjusted relative risk of developing a hypersensitivity reaction during IV-DPT versus OR-DPT was 1.13 (95% confidence interval (CI)0.57-2.22). Conclusion: The results suggest that OR-DPT and IV-DPT are both safe procedures when adequately performed. However, IV-DPT protocols showed a higher rate of immediate DHR during DPT probably due to the selection of basal high-risk patients to undergo IV-DPT. In conclusion, IV-DPT may be considered as an option for challenges in drug-allergy studies, entailing a precise administration.

The New Delhi metallo-ß-lactamase-1 biosensor rapidly and accurately detected antibiotic plasma concentrations in cefuroxime-treated patients.

OBJECTIVES: Therapeutic drug monitoring (TDM) of ß-lactam antibiotics in critically ill patients may benefit dose optimisation, thus improving therapeutic outcomes. However, rapidly and accurately detecting these antibiotics in blood remains a challenge. This research group recently developed a thermometric biosensor called the New Delhi metallo-ß-lactamase-1 (NDM-1) biosensor, which detects multiple classes of ß-lactam antibiotics in spiked plasma samples. METHODS: This study assessed the NDM-1 biosensor's effectiveness in detecting plasma concentrations of ß-lactam antibiotics in treated patients. Seven patients receiving cefuroxime were studied. Plasma samples collected pre- and post-antibiotic treatment were analysed using the NDM-1 biosensor and compared with liquid chromatography coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). RESULTS: The biosensor detected plasma samples without dilution, and a brief pre-treatment using a polyvinylidene fluoride filter significantly lowered matrix effects, reducing the running time to 5-8 minutes per sample. The assay's linear range for cefuroxime (6.25-200 mg/L) covered target concentrations during the trough phase of pharmacokinetics in critically ill patients. The pharmacokinetic properties of cefuroxime in treated patients determined by the NDM-1 biosensor and the UPLC-MS/MS were comparable, and the cefuroxime plasma concentrations measured by the two methods showed statistically good consistency. CONCLUSION: These data demonstrate that the NDM-1 biosensor assay is a fast, sensitive, and accurate method for detecting cefuroxime plasma concentrations in treated patients and highlights the NDM-1 biosensor as a promising tool for on-site TDM of ß-lactam antibiotics in critically ill patients.

Systematic Review of Beta-Lactam vs. Beta-Lactam plus Aminoglycoside Combination Therapy in Neutropenic Cancer Patients.

We performed a systematic review of studies that compared beta-lactams vs. beta-lactams plus aminoglycosides for the treatment of febrile neutropenia in cancer patients. METHOD: We searched CENTRAL, MEDLINE, and Embase for studies published up to October 2023, and randomized controlled trials (RCTs) that compared anti-Pseudomonas aeruginosa beta-lactam monotherapy with any combination of an anti-Pseudomonas aeruginosa beta-lactam and an aminoglycoside were included. RESULT: The all-cause mortality rate of combination therapy showed no significant differences compared with that of monotherapy (RR 0.99, 95% CI 0.84 to 1.16, high certainty of evidence). Infection-related mortality rates showed that combination therapy had a small positive impact compared with the intervention with monotherapy (RR 0.83, 95% CI 0.66 to 1.05, high certainty of evidence). Regarding treatment failure, combination therapy showed no significant differences compared with monotherapy (RR 0.99, 95% CI 0.94 to 1.03, low certainty of evidence). In the sensitivity analysis, the treatment failure data published between 2010 and 2019 showed better outcomes in the same beta-lactam group (RR 1.10 [95% CI, 1.01-1.19]). Renal failure was more frequent with combination therapy of any daily dosing regimen (RR 0.46, 95% CI 0.36 to 0.60, high certainty of evidence). CONCLUSION: We found combining aminoglycosides with a narrow-spectrum beta-lactam did not spare the use of broad-spectrum antibiotics. Few studies included antibiotic-resistant bacteria and a detailed investigation of aminoglycoside serum levels, and studies that combined the same beta-lactams showed only a minimal impact with the combination therapy. In the future, studies that include the profile of antibiotic-resistant bacteria and the monitoring of serum aminoglycoside levels will be required.