Potential involvement of beta-lactamase homologous proteins in resistance to beta-lactam antibiotics in gram-negative bacteria of the ESKAPEE group

BACKGROUND

Enzymatic degradation mediated by beta-lactamases constitutes one of the primary mechanisms of resistance to beta-lactam antibiotics in gram-negative bacteria. This enzyme family comprises four molecular classes, categorized into serine beta-lactamases (Classes A, C, and D) and zinc-dependent metallo-beta-lactamases (Class B). Gram-negative bacteria producing beta-lactamase are of significant concern, particularly due to their prevalence in nosocomial infections. A comprehensive understanding of the evolution and dissemination of this enzyme family is essential for effective control of these pathogens. In this study, we conducted the prospecting, phylogenetic analysis, and in silico analysis of beta-lactamases and homologous proteins identified in 1827 bacterial genomes with phenotypic data on beta-lactam resistance. These genomes were distributed among Klebsiella pneumoniae (45%), Acinetobacter baumannii (31%), Pseudomonas aeruginosa (14%), Escherichia coli (6%), and Enterobacter spp. (4%). Using an HMM profile and searching for conserved domains, we mined 2514, 8733, 5424, and 2957 proteins for molecular classes A, B, C, and D, respectively. This set of proteins encompasses canonical subfamilies of beta-lactamases as well as hypothetical proteins and other functional groups. Canonical beta-lactamases were found to be phylogenetically distant from hypothetical proteins, which, in turn, are closer to other representatives of the penicillin-binding-protein (PBP-like) and metallo-beta-lactamase (MBL) families. The catalytic amino acid residues characteristic of beta-lactamases were identified from the sequence alignment and revealed that motifs are less conserved in homologous groups than in beta-lactamases. After comparing the frequency of protein groups in genomes of resistant strains with those of sensitive ones applying Fisher's exact test and relative risk, it was observed that some groups of homologous proteins to classes B and C are more common in the genomes of resistant strains, particularly to carbapenems. We identified the beta-lactamase-like domain widely distributed in gram-negative species of the ESKAPEE group, which highlights its importance in the context of beta-lactam resistance. Some hypothetical homologous proteins have been shown to potentially possess promiscuous activity against beta-lactam antibiotics, however, they do not appear to expressly determine the resistance phenotype. The selective pressure due to the widespread use of antibiotics may favor the optimization of these functions for specialized resistance enzymes.

EAACI/ENDA position paper on drug provocation testing

In drug hypersensitivity, drug provocation testing (DPT), also called drug challenge, is the gold standard for investigation. In recent years, risk stratification has become an important tool for adjusting the diagnostic strategy to the perceived risk, whilst still maintaining a high level of safety for the patient. Skin tests are recommended before DPT but may be omitted in low-risk patients. The task force suggests a strict definition of such low-risk patients in children and adults. Based on experience and evidence from studies of allergy to beta-lactam antibiotics, an algorithm on how to adjust DPT to the risk, and when to omit skin tests before DPT, is presented. For other antibiotics, non-steroidal anti-inflammatory drugs and other drugs, skin tests are poorly validated and DPT is frequently necessary. We recommend performing DPT with chemotherapeutics and biologicals to avoid unnecessary desensitization procedures and DPT with skin tests negative contrast media. We suggest DPT with anesthetics only in highly specialized centers. Specifics of DPT to proton pump inhibitors, anticonvulsants and corticosteroids are discussed. This position paper provides general recommendations and guidance on optimizing use of DPT, whilst balancing benefits with patient safety and optimizing the use of the limited available resources.

Patient Adherence to Written Instructions following Complete Allergological Evaluation for Suspected Beta-Lactam Allergy: A Tertiary Hospital Study in Greece

BACKGROUND

Beta-lactam (BL) antibiotics are among the most prescribed groups of drugs worldwide and have been implicated in a variety of allergic reactions. There is a paucity of literature regarding patient adherence to prescribed instructions following comprehensive allergy assessments.

OBJECTIVE

The objective was to follow up the clinical course of BL allergy in patients who underwent thorough allergological investigation for suspected BL allergy at a tertiary hospital and ascertain patients' compliance with the provided written instructions.

MATERIALS

An observational study in patients referred for suspected BL allergy who underwent a comprehensive allergy workup (in vivo ± in vitro tests, DPT in culprit and/or alternative BL) and who subsequently received written instructions was conducted. Data on the nature of the reported drug hypersensitivity reaction, the culprit BL drug, the allergological workup, and the detailed instructions provided in a written drug allergy report were collected retrospectively. Patients' compliance with the instructions was recorded by a telephone survey using a pre-defined questionnaire.

RESULTS

Among the 212 patients meeting the inclusion criteria, 87 patients (72.4% women; mean age 50.1 years; age range 6-84 years) responded to the telephone survey and were included in this study. Surprisingly, 45 out of 87 (51.7%) patients did not adhere to the written instructions. The primary factor contributing to non-compliance was the fear of re-occurrence of a drug-induced allergic reaction (personal and/or triggered by their treating physician reluctance), accounting for 77.7% of cases. The analysis demonstrated that the initial reaction's severity and type, as well as the outcomes of skin testing, did not correlate with compliance to instructions (p > 0.05). Surprisingly enough, a drug provocation test (DPT), irrespectively of the result, emerged as a negative predictor for adherence, with only 40.6% of DPT patients complying compared to 77.8% of those who did not undergo DPT (p = 0.005; odds ratio = 0.195; 95% confidence interval: 0.058-0.655). Variables such as performing DPT with alternative or incriminated drugs or the result of the DPT (positive-negative) were not associated with patient compliance. Conversely, the type of instructions provided exhibited a noteworthy correlation with compliance. Patients who were explicitly instructed to entirely avoid all BL antibiotics demonstrated markedly higher adherence rates (83.3%) compared to those who were advised to have a partial or complete release of BLs (31.8% and 58.1%, respectively; p < 0.05). Notably, among compliant patients who received either the original culprit drug or the alternative (32 out of 87, 36.7%), no allergic reactions were reported. In contrast, among the 12 patients with written avoidance of all BLs, subsequent BL intake led to immediate reactions (Grade I and IV) in 2 patients (16.6%).

CONCLUSIONS

A notable disparity in patient adherence to written instructions prohibiting or releasing beta-lactams was demonstrated. Less than half of the patients ultimately complied with the provided instructions, underscoring the need for tailored patients' education and strategies to improve adherence in the management of suspected BL allergy.

24/7 Therapeutic Drug Monitoring of Beta-Lactam Antibiotics with CLAM-2000

BACKGROUND

The aim of this study was to evaluate the CLAM-2000 automated preanalytical sample preparation module with integrated liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) as a method for 24/7 therapeutic drug monitoring (TDM) of beta-lactam antibiotics in routine clinical diagnostics.

METHODS

Method validation was performed using quality control samples. Method comparison was performed with routine samples from patients treated with beta-lactam antibiotics.

RESULTS

The determination of piperacillin, meropenem, ceftazidime, flucloxacillin, and cefotaxime was performed using D5-piperacillin and D6-meropenem as internal standards. The linearity of the method was within the therapeutic range of beta-lactam antibiotics. The imprecision and accuracy data obtained from quality control samples were within 15%, and the imprecision of patient samples on the instrument was less than the 5% coefficient of variation (CV). Internal standards stored in the instrument at 9 °C for at least one week were stable, which facilitated reagent use and storage.

CONCLUSION

The CLAM-2000 (Shimadzu, Kyoto, Japan) provides reproducible results as an established routine instrument and is a useful tool for 24/7 TDM of beta-lactam antibiotics in routine clinical diagnostics.

Stability of 10 Beta-Lactam Antibiotics in Human Plasma at Different Storage Conditions

BACKGROUND

Recently, several studies have assessed the effects of therapeutic drug monitoring of frequently prescribed beta-lactam antibiotics, for which they were quantified in human plasma samples. Beta-lactams are considered unstable, leading to extra challenges in quantification. Therefore, to ensure sample stability and minimize sample degradation before analysis, stability studies are crucial. This study investigated the stability of 10 frequently used beta-lactam antibiotics in human plasma at relevant storage conditions for clinical use.

METHODS

Amoxicillin, benzylpenicillin, cefotaxime, ceftazidime, ceftriaxone, cefuroxime, flucloxacillin, imipenem, meropenem, and piperacillin were analyzed using ultraperformance convergence chromatography tandem mass spectrometry and liquid chromatography tandem mass spectrometry. Their short-term and long-term stabilities were investigated by measuring quality control samples at low and high concentrations against freshly prepared calibration standards. Measured concentrations at each time point were compared with the concentrations at T = 0. Antibiotics were considered stable if recovery results were between 85% and 115%.

RESULTS

Short-term stability results indicated ceftriaxone, cefuroxime, and meropenem to be stable up to 24 hours at room temperature. All evaluated antibiotics, except imipenem, were stable on ice in a cool box for 24 hours. Amoxicillin, benzylpenicillin, and piperacillin were stable for 24 hours at 4-6°C. Cefotaxime, ceftazidime, cefuroxime, and meropenem were stable at 4-6°C up to 72 hours. Ceftriaxone and flucloxacillin were stable for 1 week at 4-6°C. Long-term stability results showed that all antibiotics were stable up to 1 year at -80°C, except imipenem and piperacillin, which were stable for 6 months at -80°C.

CONCLUSIONS

Plasma samples for amoxicillin, benzylpenicillin, cefotaxime, ceftazidime, flucloxacillin, and piperacillin may be stored for a maximum of 24 hours in a cool box. Refrigeration is suitable for plasma samples of amoxicillin, benzylpenicillin, meropenem, and piperacillin for up to 24 hours and cefotaxime, ceftriaxone, ceftazidime and cefuroxime for 72 hours. Plasma samples for imipenem should be frozen directly at -80°C. For long-term storage, plasma samples can be stored at -80°C for a maximum of 6 months for imipenem and piperacillin and 12 months for all other evaluated antibiotics.

Association between HLA alleles and beta-lactam antibiotics-related severe cutaneous adverse reactions

Introduction: Beta-lactam antibiotics are one of the most common causes of antibiotics-related severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reactions with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP). Recent evidence demonstrated that the human leukocyte antigen (HLA) polymorphisms play important roles in the development of drug-related SCARs. This study aimed to extensively characterize the associations between HLA genetic polymorphisms and several phenotypes of SCARs related to beta-lactam antibiotics. Methods: Thirty-one Thai patients with beta-lactam antibiotics-related SCARs were enrolled in the study. A total of 183 unrelated native Thai subjects without any evidence of drug allergy were recruited as the control group. Genotyping of HLA class I and class II alleles was performed. Results: Six HLA alleles including HLA-A*01:01, HLA-B*50:01, HLA-C*06:02, HLA-DRB1*15:01, HLA-DQA1*03:01, and HLA-DQB1*03:02, were significantly associated with beta-lactam antibiotics-related SCARs. The highest risk of SCARs was observed in patients with the HLA-B*50:01 allele (OR = 12.6, 95% CI = 1.1-142.9, p = 0.042), followed by the HLA-DQB1*03:02 allele (OR = 5.8, 95% CI = 1.5-22.0, p = 0.012) and the HLA-C*06:02 allele (OR = 5.7, 95% CI = 1.6-19.9, p = 0.011). According to the phenotypes of SCARs related to beta-lactam antibiotics, the higher risk of SJS/TEN was observed in patients with HLA-A*03:02, HLA-B*46:02 (OR = 17.5, 95% CI = 1.5-201.6, p = 0.033), HLA-A*02:06, HLA-B*57:01 (OR = 9.5, 95% CI = 1.3-71.5, p = 0.028), HLA-DQB1*03:02 (OR = 7.5, 95% CI = 1.8-30.9, p = 0.008), or HLA-C*06:02 (OR = 4.9, 95% CI = 1.1-21.4, p = 0.008). While eight HLA alleles including HLA-A*02:05, HLA-A*02:11, HLA-B*37:01, HLA-B*38:01, HLA-B*50:01, HLA-C*06:02, HLA-C*03:09, and HLA-DRB1*15:01 were associated with AGEP, the highest risk of AGEP was observed in patients with the HLA-B*50:01 allele (OR = 60.7, 95% CI = 4.8-765.00, p = 0.005). Among the four HLA alleles associated with DRESS including HLA-C*04:06, HLA-DRB1*04:05, HLA-DRB1*11:01, and HLA-DQB1*04:01, the HLA-C*04:06 allele had the highest risk of beta-lactam antibiotics-related DRESS (OR = 60.0, 95% CI = 3.0-1202.1, p = 0.043). However, these associations did not achieve statistical significance after Bonferroni's correction. Apart from the HLA risk alleles, the HLA-A*02:07 allele appeared to be a protective factor against beta-lactam antibiotic-related SCARs (OR = 0.1, 95% CI = 0.0-0.5, p = 3.7 × 10-4, Pc = 0.012). Conclusion: This study demonstrated the candidate HLA alleles that are significantly associated with several phenotypes of beta-lactam antibiotics-related SCARs. However, whether the HLA alleles observed in this study can be used as valid genetic markers for SCARs related to beta-lactam antibiotics needs to be further explored in other ethnicities and larger cohort studies.

Prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae among clinical isolates in Turaif general hospital, northern borders- Saudi Arabia

INTRODUCTION

Enterobacteriaceae that produce extended-spectrum beta-lactamase (ESBL) are quickly spreading, posing a threat to world healthcare.

METHODOLOGY

138 gram-negative bacteria were collected from different samples (stool, urine, wound, blood, tracheal aspirate, catheter tip, vaginal swab, sputum, and tracheal aspirate) from hospitalized patients. Samples were subcultured and identified in accordance with their biochemical reactions and culture characteristics. Against all the isolated Enterobacteriaceae, an antimicrobial susceptibility test was performed. VITEK®2 system, phenotypic confirmation, and Double-Disk Synergy Test (DDST) had been utilized to identify the ESBLs.

RESULTS

Of the 138 samples studied, the prevalence of ESBL-producing infections among the clinical samples of the present study was 26.8 % (n = 37). E. coli was the commonest ESΒL producer at 51.4% (n = 19) followed by K. pneumoniae at 27% (n = 10). The potential risk factors for the ESBL development that produces bacteria were as follows, patients with the presence of indwelling devices, previous history of hospital admission, and usage of antibiotics. ESBL is statistically (p ≤ 0.05) higher among the patients with indwelling devices, ICU admission, who had a previous hospital admission in the last 6 months as well as who was given antibiotics (quinolones and/or cephalosporins) in the last 6 months. One hundred thirty-two (95.7%) of ESBL isolates were resistant to amoxicillin, while the lowest resistance was for fosfomycin (15.2%).

CONCLUSIONS

ESBL-producing Enterobacteriaceae are highly prevalent in Turaif General Hospital setting with some potential risk factors. A strict policy to be made available on the usage of antimicrobials in hospitals and clinics should be established.

Genome-Wide Transposon Mutagenesis Screens Identify Group A Streptococcus Genes Affecting Susceptibility to β-Lactam Antibiotics

Group A streptococcus (GAS) is a Gram-positive human bacterial pathogen responsible for more than 700 million infections annually worldwide. Beta-lactam antibiotics are the primary agents used to treat GAS infections. Naturally occurring GAS clinical isolates with decreased susceptibility to beta-lactam antibiotics attributed to mutations in PBP2X have recently been documented. This prompted us to perform a genome-wide screen to identify GAS genes that alter beta-lactam susceptibility in vitro. Using saturated transposon mutagenesis, we screened for GAS gene mutations conferring altered in vitro susceptibility to penicillin G and/or ceftriaxone, two beta-lactam antibiotics commonly used to treat GAS infections. In the aggregate, we found that inactivating mutations in 150 GAS genes are associated with altered susceptibility to penicillin G and/or ceftriaxone. Many of the genes identified were previously not known to alter beta-lactam susceptibility or affect cell wall biosynthesis. Using isogenic mutant strains, we confirmed that inactivation of clpX (Clp protease ATP-binding subunit) or cppA (CppA proteinase) resulted in decreased in vitro susceptibility to penicillin G and ceftriaxone. Deletion of murA1 (UDP-N-acetylglucosamine 1-carboxyvinyltransferase) conferred increased susceptibility to ceftriaxone. Our results provide new information about the GAS genes affecting susceptibility to beta-lactam antibiotics. IMPORTANCE Beta-lactam antibiotics are the primary drugs prescribed to treat infections caused by group A streptococcus (GAS), an important human pathogen. However, the molecular mechanisms of GAS interactions with beta-lactam antibiotics are not fully understood. In this study, we performed a genome-wide mutagenesis screen to identify GAS mutations conferring altered susceptibility to beta-lactam antibiotics. In the aggregate, we discovered that mutations in 150 GAS genes were associated with altered beta-lactam susceptibility. Many identified genes were previously not known to alter beta-lactam susceptibility or affect cell wall biosynthesis. Our results provide new information about the molecular mechanisms of GAS interaction with beta-lactam antibiotics.

β-lactam precision dosing in critically ill children: Current state and knowledge gaps

There has been emerging interest in implementing therapeutic drug monitoring and model-informed precision dosing of β-lactam antibiotics in critically ill patients, including children. Despite a position paper endorsed by multiple international societies that support these efforts in critically ill adults, implementation of β-lactam precision dosing has not been widely adopted. In this review, we highlight what is known about β-lactam antibiotic pharmacokinetics and pharmacodynamics in critically ill children. We also define the knowledge gaps that present barriers to acceptance and implementation of precision dosing of β-lactam antibiotics in critically ill children: a lack of consensus on which subpopulations would benefit most from precision dosing and the uncertainty of how precision dosing changes outcomes. We conclude with opportunities for further research to close these knowledge gaps.

Effectiveness and Safety of Beta-Lactam Antibiotics with and without Therapeutic Drug Monitoring in Patients with Pseudomonas aeruginosa Pneumonia or Bloodstream Infection

This objective of this study was to compare clinical outcomes in hospitalized patients with Pseudomonas aeruginosa pneumonia (PNA) or bloodstream infection (BSI) receiving beta-lactam antibiotic (BLA) infusions with and without the guidance of therapeutic drug monitoring (TDM). A retrospective, parallel cohort study was conducted at two academic medical centers between December 2015 and January 2020, UF Shands Gainesville, which uses BLA TDM for select patients (BLA TDM), and UF Health Jacksonville, which does not use BLA TDM (No-BLA TDM). All hospitalized adult patients with respiratory or blood culture positive for P. aeruginosa who met diagnosis criteria for lower respiratory tract infection with a positive P. aeruginosa respiratory culture and who received ≥48 h of intravenous BLA with in vitro susceptibility within 72 h of positive culture collection were included. The primary outcome was a composite of presumed treatment failure defined as the presence of any of the following from index-positive P. aeruginosa culture collection to the end of BLA therapy: all-cause mortality, escalation of and/or additional antimicrobial therapy for P. aeruginosa infection after 48 h of treatment with susceptible BLA due to worsening clinical status, or transfer to a higher level of care (i.e., the intensive care unit [ICU]). Analyses were adjusted for possible confounding with inverse probability of treatment weighting (IPTW). Two-hundred patients were included (BLA TDM, n = 95; No-BLA TDM, n = 105). In IPTW-adjusted analysis of the primary composite endpoint, BLA TDM demonstrated a significant decrease in presumed treatment failure compared to No-BLA TDM (adjusted odds ratio [aOR] 0.037, 95% confidence interval [CI] [0.013 to 0.107]; P < 0.001). BLA TDM had more 30-, 60- and 90-day infection-related readmissions ([aOR], 11.301, 95% CI (3.595 to 35.516); aOR 10.389, 95% CI [2.496 to 43.239], and aOR 24.970, 95% CI [6.703 to 93.028]) in IPTW analyses. For both unadjusted and IPTW-adjusted cohorts, there was no significant difference in hospital and ICU length of stay, adverse effects while on BLA, or microbiological eradication between BLA TDM and No-BLA TDM. In hospitalized adult patients with P. aeruginosa PNA or BSI, the use of TDM-guided BLA infusions decreased the odds of presumed treatment failure compared to patients receiving BLA infusions without TDM guidance. Future studies should evaluate BLA TDM impact on readmission.

Why We May Need Higher Doses of Beta-Lactam Antibiotics: Introducing the 'Maximum Tolerable Dose'

The surge in antimicrobial resistance and the limited availability of new antimicrobial drugs has fueled the interest in optimizing antibiotic dosing. An ideal dosing regimen leads to maximal bacterial cell kill, whilst minimizing the risk of toxicity or antimicrobial resistance. For beta-lactam antibiotics specifically, PK/PD-based considerations have led to the widespread adoption of prolonged infusion. The rationale behind prolonged infusion is increasing the percentage of time the beta-lactam antibiotic concentration remains above the minimal inhibitory concentration (%fT>MIC). The ultimate goal of prolonged infusion of beta-lactam antibiotics is to improve the outcome of infectious diseases. However, merely increasing target attainment (or the %fT>MIC) is unlikely to lead to improved clinical outcome for several reasons. First, the PK/PD index and target are dynamic entities. Changing the PK (as is the case if prolonged instead of intermittent infusion is used) will result in different PK/PD targets and even PK/PD indices necessary to obtain the same level of bacterial cell kill. Second, the minimal inhibitory concentration is not a good denominator to describe either the emergence of resistance or toxicity. Therefore, we believe a different approach to antibiotic dosing is necessary. In this perspective, we introduce the concept of the maximum tolerable dose (MTD). This MTD is the highest dose of an antimicrobial drug deemed safe for the patient. The goal of the MTD is to maximize bacterial cell kill and minimize the risk of antimicrobial resistance and toxicity. Unfortunately, data about what beta-lactam antibiotic levels are associated with toxicity and how beta-lactam antibiotic toxicity should be measured are limited. This perspective is, therefore, a plea to invest in research aimed at deciphering the dose−response relationship between beta-lactam antibiotic drug concentrations and toxicity. In this regard, we provide a theoretical approach of how increasing uremic toxin concentrations could be used as a quantifiable marker of beta-lactam antibiotic toxicity.

Results of patch testing in Acute generalized exanthematous pustulosis (AGEP): a literature review

The literature on positive patch test results in acute generalized exanthematous pustulosis (AGEP) is reviewed. 93 drugs were identified that have together caused 259 positive patch tests in 248 patients suffering from AGEP. The drug classes causing the highest number of reactions are beta-lactam antibiotics (25.9%), other antibiotics (20.8%), iodinated contrast media (7.3%) and corticosteroids (5.4%), together accounting for nearly 60% of all reactions. The highest number of reactions to individual drugs was to amoxicillin (n=36), followed by pristinamycin (n=25), diltiazem (n=14), amoxicillin-clavulanic acid (n=13), clindamycin (n=11) and iomeprol (n=8); 59 of the 93 drugs each caused a single case only. The "Top-10" drugs together caused over 50% of all reactions. The sensitivity of patch testing (percentage of positive reactions) in patients with AGEP is largely unknown, but may generally be around 50%, which also applies to pristinamycin. Patch testing in AGEP appears to be safe, although mild recurrence of AGEP skin symptoms or other rashes may occur occasionally. Clinical aspects of AGEP, including epidemiology, etiology and pathophysiology, clinical features, histology, treatment, and prognosis are briefly presented, as are diagnosing the disease and identifying the culprit drugs with patch tests, intradermal tests, in vitro tests, and challenge tests. This article is protected by copyright. All rights reserved.

Amoxicillin Haptenation of α-Enolase is Modulated by Active Site Occupancy and Acetylation

Allergic reactions to antibiotics are a major concern in the clinic. ß-lactam antibiotics are the class most frequently reported to cause hypersensitivity reactions. One of the mechanisms involved in this outcome is the modification of proteins by covalent binding of the drug (haptenation). Hence, interest in identifying the corresponding serum and cellular protein targets arises. Importantly, haptenation susceptibility and extent can be modulated by the context, including factors affecting protein conformation or the occurrence of other posttranslational modifications. We previously identified the glycolytic enzyme α-enolase as a target for haptenation by amoxicillin, both in cells and in the extracellular milieu. Here, we performed an in vitro study to analyze amoxicillin haptenation of α-enolase using gel-based and activity assays. Moreover, the possible interplay or interference between amoxicillin haptenation and acetylation of α-enolase was studied in 1D- and 2D-gels that showed decreased haptenation and displacement of the haptenation signal to lower pI spots after chemical acetylation of the protein, respectively. In addition, the peptide containing lysine 239 was identified by mass spectrometry as the amoxicillin target sequence on α-enolase, thus suggesting a selective haptenation under our conditions. The putative amoxicillin binding site and the surrounding interactions were investigated using the α-enolase crystal structure and molecular docking. Altogether, the results obtained provide the basis for the design of novel diagnostic tools or approaches in the study of amoxicillin-induced allergic reactions.

Comparative Prevalence of Acute Kidney Injury in Chinese Patients Receiving Vancomycin with Concurrent β-Lactam Antibiotics: A Retrospective Cohort Study

PURPOSE

The combination of vancomycin and piperacillin/tazobactam (VAN + PTZ) provides a broad spectrum of activity against multiple pathogens. However, a major issue in previous research concerned significant nephrotoxicity associated with this drug combination, and most studies have been conducted in American and European countries, with no similar data available from China. Therefore, this study evaluated the nephrotoxic effects of VAN + PTZ in a large-scale Chinese cohort to determine the prevalence of acute kidney injury (AKI) in this population by comparing PTZ and vancomycin monotherapies and the combined use of vancomycin and β-lactam antibiotics.

METHODS

This retrospective cohort study identified adult patients who received vancomycin either as monotherapy or in combination with PTZ or carbapenem (VAN + CAR) for at least 48 hours at Jiangsu Province Hospital from January 1, 2017, to December 31, 2018. Patients were also evaluated for the development of AKI, defined according to the Kidney Disease Improving Global Outcome criteria. Duration of vancomycin exposure, steady-state trough vancomycin concentrations, and other risk factors for AKI were assessed. A Bayesian network meta-analysis was conducted to validate our results and comparatively evaluate the nephrotoxicity of β-lactam antibiotics in combination with vancomycin.

FINDINGS

In all, 752 patients were included in the present study. The prevalence of AKI was higher in the VAN + PTZ group than in the VAN and VAN + CAR groups (15.2% vs 4.0% and 6.0%, respectively). After adjustment for confounding factors, VAN + PTZ was still related to AKI (odds ratio [OR] = 4.37; 95% CI, 1.65-11.59; P = 0.003). The network meta-analysis indicated that VAN + PTZ was associated with a significantly higher risk for AKI than was VAN (OR = 3.23; 95% CI, 2.50-4.35), PTZ (OR = 2.86; 95% CI, 1.92-4.12), VAN + cefepime (FEP) (OR = 2.37; 95% CI, 1.80-3.19), or VAN + CAR (OR = 2.28; 95% CI, 1.64-3.21). However, there was no significant difference with respect to AKI prevalence among the VAN, PTZ, VAN + FEP, and VAN + CAR groups.

IMPLICATIONS

The prevalence of AKI was higher with VAN + PTZ therapy than with VAN or PTZ monotherapy or with the concurrent use of VAN and FEP or CAR in our study. Clinicians should adequately assess renal function and consider this differential risk for nephrotoxicity when choosing empiric antibiotics in hospitalized patients to minimize the rates of AKI.

Association of Virulence Genes with Antibiotic Resistance in Pakistani Uropathogenic E. coli Isolates

BACKGROUND

Escherichia coli various strains can cause alarmingly serious infections. Countries like Pakistan harbour the class of bacteria with one of the highest rates of resistance, but very little has been done to explore their genetic pool.

OBJECTIVES

This study was designed to find out the frequency of virulence genes of Uropathogenic E. coli and their association with antibiotic resistance along with the evolutionary adaptation of the selected gene through the phylogenetic tree.

METHODS

Isolates from 120 urinary tract infected patients were collected. Antibiotic sensitivity was detected by the disk diffusion method and DNA extraction was done by the boiling lysis method followed by PCR-based detection of virulence genes. The final results were analysed using the chi-square test.

RESULTS

The isolates were found to be least susceptible to nalidixic acid, followed by ampicillin, cotrimoxazole, cefotaxime, ciprofloxacin, aztreonam, amoxicillin, gentamycin, nitrofurantoin and imipenem. The iucC was the most common virulence gene among the resistant isolates. About 86% of the collected samples were found to be multi-drug resistant. Statistical analysis revealed a significant association between the iucC gene and resistance to ampicillin (P=0.03) and amoxicillin (P=0.04), and also between fimH and resistance to aztreonam (P=0.03).

CONCLUSION

This study unravels the uncharted virulence genes of UPEC in our community for the very first time. We report a high frequency of the iucC and fimH virulence genes. This, along with their positive association with resistance to beta-lactam antibiotics in the studied community, indicates their important role in the development of complicated UTIs.

A new HPLC-MS/MS analytical method for quantification of tazobactam, piperacillin, and meropenem in human plasma

A simple and fast high-performance liquid chromatography with tandem mass spectrometry method for quantification of tazobactam, piperacillin, and meropenem in human plasma has been developed and validated. Simple sample preparation with a volume of 10 μL was done by protein precipitation with a mixture of methanol-acetonitrile-water (6:2:2, v/v/v). Chromatographic separation was achieved on a Luna column with a precolumn security guard by gradient elution using a mobile phase consisting of water with the addition of 0.1% formic acid (component A) and mixture methanol-acetonitrile (8:2, v/v) with the addition of 0.1% formic acid (component B). The run time was 2.7 min. The lower limits of detection and lower limits of quantification were for piperacillin 0.03 and 0.1 mg/L, for meropenem 0.04 and 0.2 mg/L and for tazobactam 0.16 and 0.5 mg/L. The validated method was used for therapeutic monitoring of tazobactam, piperacillin, and meropenem in samples of patients treated in the intensive care unit.

Clinical Relevance of Antibiotic Susceptibility Profiles for Screening Gram-negative Microorganisms Resistant to Beta-Lactam Antibiotics

The increasing resistance to antibiotics is compromising the empirical treatment of infections caused by resistant bacteria. Rapid, efficient, and clinically applicable phenotypic methods are needed for their detection. This study examines the phenotypic behavior of β-lactam-resistant Gram-negative bacteria grown on ChromID ESBL medium with ertapenem, cefoxitin, and cefepime disks, reports on the coloration of colonies, and establishes a halo diameter breakpoint for the detection of carbapenemase-producing bacteria. We studied 186 β-lactam-resistant Gram-negative microorganisms (77 with extended spectrum beta lactamase (ESBL), 97 with carbapenemases, and 12 with AmpC β-lactamases (AmpC)). Susceptibility profiles of Gram-negative bacteria that produced ESBL, AmpC, and carbapenemases were similar to the expected profiles, with some differences in the response to cefepime of ESBL-producing microorganisms. Coloration values did not differ from those described by the manufacturer of ChromID ESBL medium. In the screening of carbapenemase production, inhibition halo diameter breakpoints for antibiotic resistance were 18 mm for Enterobacterales and ertapenem, 18 mm for Pseudomonas and cefepime, and 16 mm for Acinetobacter baumannii and cefepime. This innovative phenotypic approach is highly relevant to clinical laboratories, combining susceptibility profiles with detection by coloration of high-priority resistant microorganisms such as carbapenemase-producing A. baumannii, carbapenemase-producing Pseudomonas spp., and ESBL and/or carbapenemase-producing Enterobacterales.

Omics Approaches Applied to Penicillium chrysogenum and Penicillin Production: Revealing the Secrets of Improved Productivity

Penicillin biosynthesis by Penicillium chrysogenum is one of the best-characterized biological processes from the genetic, molecular, biochemical, and subcellular points of view. Several omics studies have been carried out in this filamentous fungus during the last decade, which have contributed to gathering a deep knowledge about the molecular mechanisms underlying improved productivity in industrial strains. The information provided by these studies is extremely useful for enhancing the production of penicillin or other bioactive secondary metabolites by means of Biotechnology or Synthetic Biology.

Guideline on diagnostic procedures for suspected hypersensitivity to beta-lactam antibiotics: Guideline of the German Society for Allergology and Clinical Immunology (DGAKI) in collaboration with the German Society of Allergology (AeDA), German Society for Pediatric Allergology and Environmental Medicine (GPA), the German Contact Dermatitis Research Group (DKG), the Austrian Society for Allergology and Immunology (ÖGAI), and the Paul-Ehrlich Society for Chemotherapy (PEG)

This guideline on diagnostic procedures for suspected beta-lactam antibiotic (BLA) hypersensitivity was written by the German and Austrian professional associations for allergology, and the Paul-Ehrlich Society for Chemotherapy in a consensus procedure according to the criteria of the German Association of Scientific Medical Societies. BLA such as penicillins and cephalosporins represent the drug group that most frequently triggers drug allergies. However, the frequency of reports of suspected allergy in patient histories clearly exceeds the number of confirmed cases. The large number of suspected BLA allergies has a significant impact on, e.g., the quality of treatment received by the individual patient and the costs to society as a whole. Allergies to BLA are based on different immunological mechanisms and often manifest as maculopapular exanthema, as well as anaphylaxis; and there are also a number of less frequent special clinical manifestations of drug allergic reactions. All BLA have a beta-lactam ring. BLA are categorized into different classes: penicillins, cephalosporins, carbapenems, monobactams, and beta-lactamase inhibitors with different chemical structures. Knowledge of possible cross-reactivity is of considerable clinical significance. Whereas allergy to the common beta-lactam ring occurs in only a small percentage of all BLA allergic patients, cross-reactivity due to side chain similarities, such as aminopenicillins and aminocephalosporins, and even methoxyimino cephalosporins, are more common. However, the overall picture is complex and its elucidation may require further research. Diagnostic procedures used in BLA allergy are usually made up of four components: patient history, laboratory diagnostics, skin testing (which is particularly important), and drug provocation testing. The diagnostic approach - even in cases where the need to administer a BLA is acute - is guided by patient history and risk - benefit ratio in the individual case. Here again, further studies are required to extend the present state of knowledge. Performing allergy testing for suspected BLA hypersensitivity is urgently recommended not only in the interests of providing the patient with good medical care, but also due to the immense impact of putative BLA allergies on society as a whole.

Identification of 2'-O-methylation Site by Investigating Multi-feature Extracting Techniques

BACKGROUND

RNA methylation is a reversible post-transcriptional modification involving numerous biological processes. Ribose 2'-O-methylation is part of RNA methylation. It has shown that ribose 2'-O-methylation plays an important role in immune recognition and other pathogenesis.

OBJECTIVE

We aim to design a computational method to identify 2'-O-methylation.

METHODS

Different from the experimental method, we propose a computational workflow to identify the methylation site based on the multi-feature extracting algorithm.

RESULTS

With a voting procedure based on 7 best feature-classifier combinations, we achieved Accuracy of 76.5% in 10-fold cross-validation. Furthermore, we optimized features and input the optimized features into SVM. As a result, the AUC reached to 0.813.

CONCLUSION

The RNA sample, especially the negative samples, used in this study are more objective and strict, so we obtained more representative results than state-of-arts studies.

Evaluation of studies on extended versus standard infusion of beta-lactam antibiotics

PURPOSE

To summarize the current literature on the use and clinical efficacy of extended-infusion (EI) beta-lactam antibiotics, including piperacillin-tazobactam, meropenem, and cefepime.

SUMMARY

Gram-negative infections are a serious concern among hospitalized patients and require innovative pharmacokinetic dosing strategies to achieve clinical success, especially as the emergence of resistant gram-negative pathogens has outpaced the development of new antibiotics. Beta-lactam antibiotics exhibit time-dependent activity, which means that optimal efficacy is achieved when free drug concentrations stay above the minimum inhibitory concentration for an extended duration of the recommended dosage interval. EI piperacillin-tazobactam therapy has demonstrated improved clinical outcomes and decrease mortality in critically ill patients with gram-negative infections, particularly Pseudomonas aeruginosa infections. EI meropenem has shown higher therapeutic success rates for patients with febrile neutropenia and shorter intensive care unit (ICU) length of stay (LOS) with a reduction in ventilator days in patients with multidrug-resistant ventilator-associated pneumonia. However, a larger study showed no difference in clinical outcomes between standard-infusion and EI meropenem. EI cefepime has been associated with decreased mortality and shorter ICU LOS in patients with Pseudomonas aeruginosa infections. Common challenges associated with EI beta-lactam antibiotics include Y-site incompatibilities, lack of intravenous access, and tubing residuals. It is important to note that factors such as diverse patient populations and study methodology, along with various antibiotic dose regimens, may have contributed to conflicting data on EI beta-lactam therapy.

CONCLUSION

Based on most published literature, there appears to be a favorable trend toward use of EI beta-lactam therapy in clinical practice, particularly in critically ill patients with gram-negative infections.

Pharmacokinetic aspects of beta-lactam antibiotic therapy in intensive care unit patients: A one-center experience with TDM

Early and appropriate antibiotic therapy remains the key intervention for successful treatment of infection in critically ill patients, particularly in the current era of increasing antibiotic resistance. Optimization of the antimicrobial dosing regimens to achieve therapeutic plasma concentrations and concentrations at the site of infection is crucial for maximizing the therapeutic response and minimizing the risk of organ toxicity and is also an important tool to avoid the resistance emergence. Beta-lactam antibiotics have been considered relatively safe and, as opposed to aminoglycosides, therapeutic drug monitoring as a tool conventionally used primarily to minimize toxicity in drugs with narrow therapeutic window or complex pharmacokinetics, has not been provided routinely yet. However, emerging data suggest that optimal antibiotic exposure may not be achieved with traditional dosing strategies in a significant number of critically ill patients and, on the contrary, concerns about insufficient plasma concentrations leading to microbiological and clinical failure are warranted. The treatment of infections in the intensive care unit (ICU) patients is often challenging because of disease complexity, pathophysiologic alterations they undergo and reduced susceptibility of nosocomial pathogens. Therefore, it is of paramount importance to update current recommendations on dosing of beta-lactam antibiotics in severe infections and therapeutic drug monitoring may be regarded as the only exact method to ensure pharmacodynamics target achievement. Na Homolce Hospital is one of the first medical institutions in the Czech Republic where the practice of routine TDM of beta-lactam antibiotics in ICU-patients has been established. In this paper, we introduce our experience and first case reports.

Is Ciprofloxacin in Combination With Beta-lactam Antibiotics a Recipe for Thrombocytosis?: A Case Report of Thrombocytosis in a Patient Receiving Ciprofloxacin and Ceftriaxone

Thrombocytosis is defined as a platelet count greater than 400,000/mcL. We report the case of a patient who developed thrombocytosis after receiving ciprofloxacin and ceftriaxone therapy. A 73-year-old African-American female presented to the hospital with altered mental status attributed to sepsis and urinary tract infection. Patient was initiated on multiple empiric antibiotic therapy and was subsequently transitioned to ciprofloxacin and ceftriaxone at different times as definitive therapy for treatment of Escherichia coli bacteremia and Escherichia coli urinary tract infection. The patient developed thrombocytosis during and/or proximally to the administration of ciprofloxacin and ceftriaxone. A myeloproliferative source for the thrombocytosis was ruled out by the hematology/oncology team with a negative Janus kinase 2 V617F mutation assay result. In addition, other nondrug reactive sources of thrombocytosis (infection and anemia) were generally ruled out because the thrombocytosis was proximally linked with ciprofloxacin and ceftriaxone administration. The Naranjo Adverse Drug Reaction Probability Scale assigned a score of 5, indicating ciprofloxacin or ceftriaxone independently or in combination as a probable cause of thrombocytosis. This case report suggests that ciprofloxacin in combination with ceftriaxone (a beta-lactam antibiotic) may be a probable cause of thrombocytosis.

Novel Population Pharmacokinetic Approach to Explain the Differences between Cystic Fibrosis Patients and Healthy Volunteers via Protein Binding

The pharmacokinetics in patients with cystic fibrosis (CF) has long been thought to differ considerably from that in healthy volunteers. For highly protein bound β-lactams, profound pharmacokinetic differences were observed between comparatively morbid patients with CF and healthy volunteers. These differences could be explained by body weight and body composition for β-lactams with low protein binding. This study aimed to develop a novel population modeling approach to describe the pharmacokinetic differences between both subject groups by estimating protein binding. Eight patients with CF (lean body mass [LBM]: 39.8 ± 5.4kg) and six healthy volunteers (LBM: 53.1 ± 9.5kg) received 1027.5 mg cefotiam intravenously. Plasma concentrations and amounts in urine were simultaneously modelled. Unscaled total clearance and volume of distribution were 3% smaller in patients with CF compared to those in healthy volunteers. After allometric scaling by LBM to account for body size and composition, the remaining pharmacokinetic differences were explained by estimating the unbound fraction of cefotiam in plasma. The latter was fixed to 50% in male and estimated as 54.5% in female healthy volunteers as well as 56.3% in male and 74.4% in female patients with CF. This novel approach holds promise for characterizing the pharmacokinetics in special patient populations with altered protein binding.

Plasticity of Escherichia coli cell wall metabolism promotes fitness and antibiotic resistance across environmental conditions

Although the peptidoglycan cell wall is an essential structural and morphological feature of most bacterial cells, the extracytoplasmic enzymes involved in its synthesis are frequently dispensable under standard culture conditions. By modulating a single growth parameter-extracellular pH-we discovered a subset of these so-called 'redundant' enzymes in Escherichia coli are required for maximal fitness across pH environments. Among these pH specialists are the class A penicillin binding proteins PBP1a and PBP1b; defects in these enzymes attenuate growth in alkaline and acidic conditions, respectively. Genetic, biochemical, and cytological studies demonstrate that synthase activity is required for cell wall integrity across a wide pH range and influences pH-dependent changes in resistance to cell wall active antibiotics. Altogether, our findings reveal previously thought to be redundant enzymes are instead specialized for distinct environmental niches. This specialization may ensure robust growth and cell wall integrity in a wide range of conditions.

Editorial note

This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Paper-Based Enzyme Competition Assay for Detecting Falsified β-Lactam Antibiotics

Falsified and substandard antibiotics are a growing worldwide problem that leads to increased patient mortality and decreased trust in healthcare, and contributes to antimicrobial resistance. Monitoring falsified antibiotics is difficult because most falsified pharmaceuticals are most commonly found in developing countries, where detecting the active ingredient is difficult due to lack of access to complex instrumentation. Herein, we describe the development and optimization of a microfluidic paper-based analytical device (μPAD) to detect the active ingredient in the most falsified class of antibiotics, β-lactams. The assay is based on enzyme competition, making it the first demonstrated competitive enzyme assay reported in paper-based devices. The assay uses nitrocefin, a chromogenic substrate, to compete with β-lactam antibiotics in a reaction with β-lactamase. A yellow color indicates legitimate drugs, while a color change from yellow to red indicates falsified drugs. In addition to testing for the active ingredient, another section of the device was added to test the sample pH to further verify results and identify common falsified ingredients like aspirin or baking soda. Calibration curves for four different antibiotics, including cefazolin, have been generated making it the first paper-based device capable of detecting both cephalosporin and penicillin antibiotics. The μPAD has also been tested with common falsified ingredients and four antibiotics in tablet or injectable form, demonstrating its potential for in-field falsified antibiotic testing.

Targeting the Nonmevalonate Pathway in Burkholderia cenocepacia Increases Susceptibility to Certain β-Lactam Antibiotics

The nonmevalonate pathway is the sole pathway for isoprenoid biosynthesis in Burkholderia cenocepacia and is possibly a novel target for the development of antibacterial chemotherapy. The goals of the present study were to evaluate the essentiality of dxr, the second gene of the nonmevalonate pathway, in B. cenocepacia and to determine whether interfering with the nonmevalonate pathway increases susceptibility toward antibiotics. To this end, a rhamnose-inducible conditional dxr knockdown mutant of B. cenocepacia strain K56-2 (B. cenocepacia K56-2dxr) was constructed, using a plasmid which enables the delivery of a rhamnose-inducible promoter in the chromosome. Expression of dxr is essential for bacterial growth; the growth defect observed in the dxr mutant could be complemented by expressing dxr in trans under the control of a constitutive promoter, but not by providing 2-C-methyl-d-erythritol-4-phosphate, the reaction product of DXR (1-deoxy-d-xylulose 5-phosphate reductoisomerase). B. cenocepacia K56-2dxr showed markedly increased susceptibility to the β-lactam antibiotics aztreonam, ceftazidime, and cefotaxime, while susceptibility to other antibiotics was not (or was much less) affected; this increased susceptibility could also be complemented by in trans expression of dxr A similarly increased susceptibility was observed when antibiotics were combined with FR900098, a known DXR inhibitor. Our data confirm that the nonmevalonate pathway is essential in B. cenocepacia and suggest that combining potent DXR inhibitors with selected β-lactam antibiotics is a useful strategy to combat B. cenocepacia infections.

Covariate determinants of effective dosing regimens for time-dependent beta-lactam antibiotics for critically ill patients

AIMS

Critically ill patients undergoing aggressive fluid resuscitation and treated empirically with hydrosoluble time-dependent beta-lactam antibiotics are at risk for sub-therapeutic plasma concentrations. The aim of this study was to assess the impact of two covariates - creatinine clearance (Cl_cr) and cumulative fluid balance (CFB) on pharmacokinetics/pharmacodynamics (PK/PD) target attainment within a week of treatment with meropenem (ME) or piperacillin/tazobactam (PIP/TZB).

METHODS

In this prospective observational pharmacokinetic (PK) study, 18 critically ill patients admitted to a surgical Intensive Care Unit (ICU) were enrolled. The primary PK/PD target was free antibiotic concentrations above MIC at 100% of the dosing interval (100%fT>MIC) to obtain maximum bactericidal activity. Drug concentration was measured using liquid chromatography-tandem mass spectrometry.

RESULTS

The treatment of both 8 septic patients with IV extended ME dosing 2 g/3 h q8 h and 10 polytraumatized patients with IV intermittent PIP/TZB dosing 4.0/0.5 g q8 h was monitored. 8/18 patients (44%) manifested augmented renal clearence (ARC) where Cl_cr ≥130 mL/min/1.73 m². Maximum changes were reported on days 2-3: the median positive CFB followed by the large median volume of distribution: Vd_me=70.3 L (41.9-101.5), Vd_pip = 46.8 L (39.7-60.0). 100%fT_me>MIC was achieved in all patients on ME (aged ≥60 years), and only in two patients (non-ARC, aged ≥65 years) out of 10 on PIP/TZB. A mixed model analysis revealed positive relationship of CFB_pip with Vd_pip (P=0.021).

CONCLUSION

Assuming that the positive correlation between CFB and Vd exists for piperacillin in the setting of the pathological state, then CFB should predict Vd_pip across subjects at each and every time point.

Danger lurking in the "unknowns": structure-to-function studies of hypothetical protein Bleg1_2437 from Bacillus lehensis G1 alkaliphile revealed an evolutionary divergent B3 metallo-beta-lactamase

The effectiveness of β-lactam antibiotics as chemotherapeutic agents to treat bacterial infections is gradually threatened with the emergence of antibiotic resistance mechanism among pathogenic bacteria through the production metallo-β-lactamase (MBL). In this study, we discovered a novel hypothetical protein (HP) termed Bleg1_2437 from the genome of alkaliphilic Bacillus lehensis G1 which exhibited MBL-like properties of B3 subclass; but evolutionary divergent from other circulating B3 MBLs. Domain and sequence analysis of HP Bleg1_2437 revealed that it contains highly conserved Zn2+-binding residues such as H54, H56, D58, H59, H131 and H191, important for catalysis, similar with the subclass B3 of MBL. Built 3-D Bleg1_2437 structure exhibited an αββα sandwich layer similar to the well-conserved global topology of MBL superfamily. Other features include a ceiling and floor in the model which are important for accommodation and orientation of β-lactam antibiotics docked to the protein model showed interactions at varying degrees with residues in the binding pocket of Bleg1_2437. Hydrolysis activity towards several β-lactam antibiotics was proven through an in vitro assay using purified recombinant Bleg1_2437 protein. These findings highlight the presence of a clinically important and evolutionary divergent antibiotics-degrading enzyme within the pools of uncharacterized HPs.

Genetic variants associated with drugs-induced immediate hypersensitivity reactions: a PRISMA-compliant systematic review

Drug hypersensitivity includes allergic (AR) and nonallergic reactions (NARs) influenced by genetic predisposition. We performed a systematic review of genetic predictors of IgE-mediated AR and NAR with MEDLINE and PubMed search engine between January 1966 and December 2014. Among 3110 citations, the search selected 53 studies, 42 of which remained eligible. These eligible studies have evaluated genetic determinants of immediate reactions (IR) to beta-lactams (n = 19), NAR against aspirin (n = 12) and other nonsteroidal anti-inflammatory drugs (NSAIDs) (n = 8), and IR to biologics (n = 3). We reported two genomewide association studies and four case-control studies on candidate genes validated by replication. Genes involved in IR to beta-lactams belonged to HLA type 2 antigen processing, IgE production, atopy, and inflammation, including 4 genes validated by replications, HLA-DRA, ILR4, NOD2, and LGALS3. Genes involved in NAR to aspirin belonged to arachidonic acid pathway, membrane-spanning 4A gene family, histamine production pathway, and pro-inflammatory cytokines, while those involved in NAR to all NSAIDs belonged to arachidonic acid pathway and HLA antigen processing pathway. ALOX5 was a common predictor of studies on NAR to both aspirin and NSAIDs. Although these first conclusions could be drawn, this review highlights also the lack of reliable data and the need for replicating studies in contrasted populations, taking into account worldwide allele frequencies, gene-gene interactions, and contrasted situations of environmental exposure.

Three-times-weekly, post-dialysis cefepime therapy in patients on maintenance hemodialysis: a retrospective study

BACKGROUND

In hemodialysis patients, post-dialysis treatment with intravenous antibiotics permits even severe infections to be managed on an outpatient basis. Cefepime is a fourth-generation cephalosporin with a broad spectrum of action in monotherapy. We report on the pharmacokinetics of cefepime in post-dialysis therapy.

METHODS

Since June 2012, twelve infections were treated with post-dialysis cefepime in 9 patients on high-flux hemodialysis. The initial post-dialysis dose of cefepime was approximately 15 mg/kg. The following doses were adapted according to the trough serum levels obtained before the subsequent dialysis in order to be above the EUCAST breakpoints for susceptible organisms and above the MIC90. Residual plasma concentrations were determined before (n = 30) and after (n = 17) dialysis by liquid chromatography-mass spectrometry.

RESULTS

Overall, the mean ± SD dose of cefepime was 920 ± 270 mg (14.5 ± 5.1 mg/kg), but it was significantly lower before the 48 h interval (775 ± 210 mg or 12.7 ± 4.5 mg/kg) compared to the 72 h interval (1125 ± 225 mg or 17.2 ± 4.9 mg/kg) (p < 0.05). The mean trough pre-dialysis concentrations were 10.7 ± 3.9 mg/l and 11.3 ± 5.6 mg/l at 48 and 72 h, respectively. These levels always largely exceeded the EUCAST susceptibility breakpoints for all the targeted bacteria (>1 mg/l) with the exception of Pseudomonas aeruginosa (>8 mg/l). Cefepime concentrations were higher in anuric patients compared to those with preserved diuresis (15.6 ± 3.5 vs 9.25 ± 3.6 mg/l; p < 0.001) and decreased on average by 81 % during dialysis (from 10.5 ± 3.7 to 1.96 ± 1.2 mg/l; p < 0.001). The clinical outcome of all patients was good.

CONCLUSIONS

Outpatient treatment with cefepime administered post-dialysis three-times-weekly was effective and well-tolerated in our patients. According to our data, in patients infected by highly susceptible pathogens a fixed dose of cefepime of 1 g before every 48-h interval and of 1.5 g before every 72-h interval should be recommended, without need of routine monitoring of the cefepime blood levels. In patients having an infection with less susceptibles pathogens as P. aeruginosa, and particularly in those among them exhibiting residual renal function, higher initial doses are necessary (1.5 g before a 48-h interval and 2.0 g before a 72-h interval) with adaption according to the subsequent pre-dialysis trough serum levels.

Dissociation of cephamycin C and clavulanic acid biosynthesis by 1,3-diaminopropane in Streptomyces clavuligerus

Streptomyces clavuligerus produces simultaneously cephamycin C (CephC) and clavulanic acid (CA). Adding 1,3-diaminopropane to culture medium stimulates production of beta-lactam antibiotics. However, there are no studies on the influence of this diamine on coordinated production of CephC and CA. This study indicates that 1,3-diaminopropane can dissociate CephC and CA productions. Results indicated that low diamine concentrations (below 1.25 g l(-1)) in culture medium increased CA production by 200%, but not that of CephC. Conversely, CephC production increased by 300% when 10 g l(-1) 1,3-diaminopropane was added to culture medium. Addition of just L-lysine (18.3 g l(-1)) to culture medium increased both biocompounds. On the other hand, while L-lysine plus 7.5 g l(-1) 1,3-diaminopropane increased volumetric production of CephC by 1100%, its impact on CA production was insignificant. The combined results suggest that extracellular concentration of 1,3-diaminopropane may trigger the dissociation of CephC and CA biosynthesis in S. clavuligerus.

Identifying opportunities in EHR to improve the quality of antibiotic allergy data

BACKGROUND

Antimicrobial resistance is a growing, global public health crisis, due in large part to the overuse and misuse of antibiotics. Understanding medication allergy data and allergy reactions that are documented in electronic health records (EHRs) can help to identify opportunities to improve the quality of documentation of beta-lactam allergies, thus potentially reducing the prescribing of alternative antibiotics.

METHODS

Medication allergies and allergy reactions recorded in the EHR for 319 051 patients seen across 32 community health centers were reviewed. Patients with a beta-lactam allergy recorded in their EHR were identified. Free text, as well as standardized allergy and allergy reaction fields, were analyzed.

RESULTS

Among patients, 9.1% (n = 29 095) had evidence of a beta-lactam allergy recorded in their EHR. Women, white, and non-Hispanic patients were more likely to have a documented allergy compared to men, black, and Hispanic patients. Among all patients with a documented beta-lactam allergy, 36.2% had an empty or missing allergy reaction description in their EHR.

CONCLUSIONS

Findings suggest that current EHR documentation practices among the health centers reviewed do not provide enough information on allergic reactions to allow providers to discern between true allergies and common, but anticipated, drug side effects. Improved EHR documentation guidance, training that reinforces the use of standardized data and more detailed recording of allergic reactions, combined with initiatives to address patient barriers including health literacy, may help to improve the accuracy of drug allergies in patients' records. These initiatives, combined with antimicrobial stewardship programs, can help to reduce inappropriate prescribing of alternative antibiotics when beta-lactam antibiotics are first-line and can be tolerated.

The prevalence and reliability of self-reported penicillin allergy in a community hospital

Background

Penicillin (PCN) accounts for most cases of antibiotic allergies. Reported PCN allergy deprives the patient from this class of antibiotics and creates hesitancy in using other beta-lactam antibiotics. The aim of this study is to report the prevalence of self-reported PCN allergy among adult patients admitted to the hospital and to examine the probable validity of these reports.

Methods

A questionnaire was conducted among 192 patients with self-reported PCN allergy who were admitted to a community hospital between July 25, 2011 and January 25, 2012. Patients admitted with an infection and treated with a beta-lactam were also followed until hospital discharge.

Results

The mean age of patients at the time of their self-reported allergic reaction was 20.3 years. The most common allergic symptoms reported in decreasing order of frequency were itchy rash, angioedema, and urticaria. Based on analysis of the questionnaires, 121 patients (63.0%) had probable PCN allergy, 54 (28.1%) had possible PCN allergy, and 17 (8.9%) were unlikely to have a PCN allergy. Fifty-one participants (26.6%) had self-reported subsequent exposure to PCN in their life. This subsequent exposure was well tolerated in 86.3% of the participants. Fifty participants (25.9%) had self-reported subsequent exposure to a first generation cephalosporin and it was well tolerated in 78.4% of them.

Conclusion

Taking a detailed history from patients with self-reported PCN allergy can help to distinguish a true PCN allergy from a false positive report of allergy and hence allow clinicians to use this important class of antibiotics when truly indicated.

Definition of the common and divergent steps in carbapenem β-lactam antibiotic biosynthesis

Approximately 50 naturally occurring carbapenem β-lactam antibiotics are known. All but one of these have been isolated from Streptomyces species and are disubstituted structural variants of a simple core that is synthesized by Pectobacterium carotovorum (Erwinia carotovora), a phylogenetically distant plant pathogen. While the biosynthesis of the simple carbapenem, (5R)-carbapen-2-em-3-carboxylic acid, is impressively efficient requiring only three enzymes, CarA, CarB and CarC, the formation of thienamycin, one of the former group of metabolites from Streptomyces, is markedly more complex. Despite their phylogenetic separation, bioinformatic analysis of the encoding gene clusters suggests that the two pathways could be related. Here we demonstrate with gene swapping, stereochemical and kinetics experiments that CarB and CarA and their S. cattleya orthologues, ThnE and ThnM, respectively, are functionally and stereochemically equivalent, although their catalytic efficiencies differ. The biosynthetic pathways, therefore, to thienamycin, and likely to the other disubstituted carbapenems, and to the simplest carbapenem, (5R)-carbapen-2-em-3-carboxylic acid, are initiated in the same manner, but share only two common steps before diverging.

Beta-lactam antibiotic sensitization and its relationship to allergic diseases in tertiary hospital nurses

Purpose

Skin allergies through type 1 and 4 hypersensitivity reactions are the most frequent manifestations of drug allergies. We had previously experienced a case of a nurse with cefotiam-induced contact urticaria syndrome. To aid in preventing the progression of drug-induced allergic disease in nurses, we conducted a survey of tertiary hospital nurses who were likely to have been exposed professionally to antibiotics.

Methods

All 539 staff nurses at a tertiary hospital were asked to respond to a questionnaire regarding antibiotic exposure. Of the 457 nurses (84.8%) who responded, 427 (79.2%) received a physical examination of the hands and 318 (59.0%) received skin prick tests with the β-lactam antibiotics cefotiam, cefoperazone, ceftizoxime, flomoxef, piperacillin and penicillin G.

Results

A positive response to at least one of the antibiotics occurred in 8 (2.6%) of the 311 subjects included in the analysis and stages 1 and 2 contact urticaria syndrome were observed in 38 (8.9%) and 3 (0.7%) of 427 nurses, respectively. The frequencies of a positive antibiotic skin test (6.9 versus 1.3%, χ²=7.15, P=0.018), stage 1 contact urticaria syndrome (14.4 versus 7.4%, χ²=4.33, P=0.038) and drug allergy (15.3 versus 3.6%, χ²=18.28, P=0.000) were higher in subjects with a positive skin allergy history than in those without. Allergic rhinitis (P=0.02, OR=3.86, CI=1.23-12.06), night cough (P=0.04, OR=3.12, CI=1.03-9.41) and food allergy (P=0.00, OR=9.90, CI=3.38-29.98) were significant risk factors for drug allergy.

Conclusions

Antibiotic sensitization and drug allergy occurred more frequently in nurses with a positive skin allergy history. Atopy may be an important risk factor for drug allergy.

Detection of Beta-Lactam Antibiotics in Bulk Tank Milk

A total of 100 raw bulk tank milk samples were tested using both the Delvotest-P agar diffusion test and the Delvo-X-Press enzyme linked immunosorbent assay (ELISA) test for beta-lactam antibiotics. Samples were spiked with various levels of different beta-lactams and detection levels were compared to the manufacturer's reported sensitivities and safe levels currently published for raw milk in Canada's Food and Drugs Regulations. In all cases, both tests met or exceeded the reported test sensitivities and all currently published safe levels, with the exception of cloxacillin on the Delvo-X-Press test only. Current safe levels for cloxacillin are 30 ng/ml; this test only detected levels of 70 ng/ml, despite the manufacturer's claim of 50 ng/ml. No false-positive or -negative samples were found using either test method. Both tests were easy to perform, but the Delvo-X-Press required more technical ability. In view of the decreased detection time offered by the Delvo-X-Press (10 min) (Delvotest-P, 2.5 h) and the test's simplicity, this test should be considered as a screening test on the dairy loading dock before milk is accepted into the plant. In addition, the Delvo-X-Press offers an increased shelf life compared with other ELISA tests, because of the separate packaging for test reagents, which is certainly advantageous for infrequent testing.