Journal of Antimicrobial Chemotherapy最新文献

Background: Increasing antibiotic resistance in Helicobacter pylori necessitates research on new active molecules. In 2017, delafloxacin, a new fluoroquinolone with chemical properties of activity under acidic conditions, was approved for treatment of community-acquired bacterial pneumonia and acute bacterial skin and soft-tissue infections. Mutations in gyrA are responsible for fluoroquinolone resistance, but certain clinical isolates of H. pylori appear to display a dual phenotype: resistance to levofloxacin associated with very low delafloxacin MICs.

Objectives: To estimate epidemiological cut-off (ECOFF) values and to identify mutations in the gyrA gene, specific to FQ resistance, without increasing the MICs of delafloxacin.

Methods: Clinical strains (n = 231) were collected in the bacteriology laboratory of Poitiers University Hospital over a 2 year period to determine the ECOFF of delafloxacin. Retrospectively, 101 clinical strains with an levofloxacin-resistant phenotype (MIC > 1 mg/L) were selected from 2018 to 2022 for delafloxacin MIC determination and QRDR (gyrA) sequencing.

Results: The estimated ECOFF of delafloxacin was ≤0.125 mg/L. No H. pylori isolate showed a levofloxacin-sensitive phenotype with a delafloxacin MIC of >0.125 mg/L. Among the levofloxacin-resistant H. pylori isolates, 53.5% had delafloxacin MICs of ≤0.125 mg/L. The N87I mutation was associated with dual levofloxacin/delafloxacin resistance (P < 0.001) in contrast to the N87K and D91N mutations (P > 0.05). Mutations D91G and D91Y were not associated with a delafloxacin resistance phenotype (P > 0.05).

Conclusions: Delafloxacin seems to be a therapeutic alternative for levofloxacin-resistant strains with greater in vitro activity. However, further clinical/biological investigations are required to determine its efficacy in H. pylori eradication.

Objectives: Pharmacodynamic parameters evaluated under conditions that simulate an infection site volume and microbial load might reveal hidden risks of resistance selection and subsequent treatment failure. The study aimed to investigate the predictive potential of MICs determined at various conditions on the antimicrobial effect and emergence of resistance.

Methods: We assessed meropenem MICs (microdilution: 0.2 mL, 5 × 105 cfu/mL; macrodilution: 2 mL, 5 × 105 cfu/mL), MICHVs (220 mL, 5 × 105 cfu/mL), MICHIs (0.2 mL, 5 × 107 cfu/mL) and MICHVIs (220 mL, 5 × 107 cfu/mL) for five Klebsiella pneumoniae strains and analysed these values alongside the results of experiments in a dynamic in vitro model. A clinically relevant meropenem dosing regimen was simulated and the starting bacterial inocula were 106 and 108 cfu/mL.

Results: The effectiveness of meropenem agreed with MICHVs for the 106 cfu/mL inoculum and with MICHIs or MICHVIs for the 108 cfu/mL inoculum. Strains characterized as resistant according to these values grew during meropenem exposure, and resistant mutants were selected.

Conclusions: Our results suggest that MICHV-based parameters may be suitable for predicting antibacterial effects and the risk of resistance development when the inoculum is 106 cfu/mL, while MICHI- or MICHVI-based parameters are suitable for these purposes when the inoculum is 108 cfu/mL. Also, the correlation between resistance selection and the MICHI-based parameter was as high as one that corresponds with a mutant prevention concentration (MPC)-based parameter; this suggests that the MPC can be replaced by the more easily determined alternative parameter MICHI.

Background: To guide antibiotic stewardship interventions, understanding for what indications antibiotics are used is essential.

Methods: In rural Burkina Faso, we measured antibiotic dispensing across all healthcare providers. From October 2021 to February 2022, we surveyed patients in Nanoro district, Burkina Faso, following visits to health centres (3), pharmacies (2), informal medicine vendors (5) and inpatients in health centres. We estimated prevalence of antibiotic use and the proportion of Watch group antibiotics by provider type and by clinical presentation, assessing compliance with WHO's AWaRe Antibiotic Book. We estimated per capita antibiotic use by multiplying prevalence of antibiotic use, mean DDD per adult treatment course, and the rate of healthcare visits per 1000 inhabitants per day, estimated from a prior household survey.

Results: Outpatient antibiotic use was more frequent after health centre visits (54.8%, of which 16.5% Watch, n = 1249) than after visits to pharmacies (26.2%, 16.3% Watch, n = 328) and informal medicine vendors (26.9%, 50.0% Watch, n = 349). The frequency of antibiotic use was highest for bronchitis (79.9% antibiotic use, of which 12.6% Watch), malaria (31.9%, 23.1% Watch), gastroenteritis (76.0%, 31.7% Watch), rhinopharyngitis (40.4%, 8.3% Watch) and undifferentiated fever (77.0%, 44.8% Watch). Compliance with WHO AWaRe guidance could have averted at least 68.4% of all Watch antibiotic use in outpatients at health centres. Community-wide, 2.9 DDD (95% CI 1.9-3.9) were used per 1000 adult inhabitants per day.

Conclusions: Most Watch antibiotic use at community level or primary care deviated from WHO guidance. Antibiotic stewardship should focus on key clinical presentations and include primary care and self-medication.

Objectives: Polymyxins are a vital class of antibiotics used to combat multidrug-resistant Gram-negative bacteria. However, their use is limited due to potential nephrotoxicity and the availability of alternative antibiotics. This review aims to examine the properties of polymyxins and the clinical advances in their use for treating infections caused by carbapenem-resistant Gram-negative bacteria (CR-GNB).

Methods: This review analyses literature on polymyxin properties and various clinical approaches, including intravenous drip infusion, nebulized or dry powder inhalation, and ointment application. Treatment efficacy in terms of bacterial eradication, cure rate and mortality rate are reviewed and evaluated.

Results: Polymyxins have been reintroduced to treat critical infections due to the increasing prevalence of CR-GNB. Clinical trials and studies have confirmed that polymyxins can effectively treat CR-GNB infections when the formulation and administration are appropriate, with acceptable levels of nephrotoxicity.

Conclusions: In the future, the development of polymyxin formulations will aim to improve their clinical effectiveness while reducing toxicity and side effects and preventing the emergence of polymyxin-resistant strains. Enhanced efficacy and minimized potential side effects can be achieved by developing new polymyxin-delivery systems that provide a smart and controlled release or customized patient administration.

Background: Infective endocarditis (IE) caused by viridans and gallolyticus group streptococci (VGS-GGS) resistant to penicillin (PEN-R; minimum inhibitory concentration ≥4 mg/L) is rare but poses therapeutic challenges.

Objectives: To describe the characteristics of patients with IE caused by PEN-R VGS-GGS, focusing on antimicrobial management.

Methods: Retrospective analysis of a prospective cohort of definite IE caused by PEN-R VGS-GGS between 2008 and 2023 in 40 Spanish hospitals. We describe clinical characteristics, management and outcome of the cases, and compare them to IE caused by VGS-GGS with susceptibility or susceptibility with increased exposure to penicillin (PEN-I).

Results: We identified nine cases of PEN-R VGS-GGS IE in a cohort of 1563 streptococcal IE (0.58%). All isolates belonged to S. mitis group. Three cases died during hospitalization and no relapse occurred at 3 months of follow-up. Compared to cases with susceptibility or PEN-I, PEN-R showed a higher rate of mitral location (78% versus 51%), surgical indication (67% versus 51%), and in-hospital mortality (33% versus 12%). Most cases (86%) showed resistance to third-generation cephalosporins. The preferred antibiotic regimen was beta-lactam-based: ceftriaxone plus gentamicin, penicillin plus gentamicin, ceftriaxone plus levofloxacin, and ceftaroline plus daptomycin. Two cases received a combination of vancomycin plus gentamicin. Levofloxacin was used in two cases in combination with ceftriaxone or daptomycin. All patients that received cardiac surgery were cured at the end of follow-up.

Conclusions: IE caused by PEN-R VGS-GGS was rare and only affected mitis group streptococci. Antibiotic combination including a beta-lactam seems to be effective in its management.

Treatment of patients with serious infections due to resistant Gram-negative bacteria remains highly problematic and has prompted clinicians to use existing antimicrobial agents in innovative ways. One approach gaining increased therapeutic use is combination therapy with IV fosfomycin. This article reviews the preclinical pharmacokinetic/pharmacodynamic (PK/PD) infection model and clinical data surrounding the use of combination therapy with IV fosfomycin for the treatment of serious infections caused by resistant Gram-negative bacteria. Data from dynamic in vitro and animal infection model studies of highly resistant Enterobacterales and non-lactose fermenters are positive and suggest IV fosfomycin in combination with a β-lactam, polymyxin or aminoglycoside produces a synergistic effect that rivals or surpasses that of other aminoglycoside- or polymyxin-containing regimens. Clinical studies performed to date primarily have involved patients with pneumonia and/or bacteraemia due to Klebsiella pneumoniae, Pseudomonas aeruginosa or Acinetobacter baumannii. Overall, the observed success rates with fosfomycin combination regimens were consistent with those reported for other combination regimens commonly used to treat these patients. In studies in which direct treatment comparisons can be derived, the results suggest that patients who received fosfomycin combination therapy had similar or improved outcomes compared with other therapies and combinations, especially when it was used in combination with a β-lactam that (1) targets PBP-3 and (2) has exceptional stability in the presence of β-lactamases. Collectively, the data indicate that combination therapy with IV fosfomycin should be considered as a potential alternative to aminoglycoside or polymyxin combinations for patients with antibiotic-resistant Gram-negative infections when benefits outweigh risks.

Objectives: To identify novel genetic elements facilitating the horizontal transfer of the oxazolidinone/phenicol resistance gene optrA and the pleuromutilin-lincosamide-streptogramin A resistance gene lsa(E) in Streptococcus suis.

Methods: The complete genomes of S. suis HB18 and two transconjugants were obtained using both the Illumina and Nanopore platforms. MICs were determined by broth microdilution. Inverse PCR was performed to identify circular forms of the novel unconventional circularizable structure (UCS), genomic island (GI) and integrative and conjugative element (ICE). Conjugation experiments assessed the transferability of optrA and lsa(E) genes in S. suis.

Results: S. suis HB18 carried a multiresistance gene cluster optrA-lsa(E)-lnu(B)-aphA-aadE-spw. This gene cluster, flanked by intact and truncated erm(B) in the same orientation, resided on a novel ICESsuHB18. Inverse PCR revealed the existence of a novel UCS, named UCS-optrA + lsa(E), which could excise the gene cluster optrA-lsa(E)-lnu(B)-aphA-aadE-spw and one copy of erm(B) from ICESsuHB18. Two transconjugants with different characteristics were obtained. In transconjugant T-JH-GI, UCS-optrA + lsa(E) excised from ICESsuHB18 inserted into the erm(B)-positive GI, designated GISsuHB18, generating the novel GISsuHB18-1. Meanwhile, in T-JH-ICE, genetic rearrangement events occurred in ICESsuHB18 and GISsuHB18, forming the novel ICESsuHB18-1.

Conclusions: This is the first report demonstrating the functionally active UCS-optrA + lsa(E) excising from ICESsuHB18 and inserting into the erm(B)-positive GISsuHB18 during the conjugation process. The location of optrA and lsa(E) on a multiresistance UCS enhances its persistence and dissemination.

Background: Studying long-term treatment outcomes of TB is time-consuming and impractical. Early and reliable biomarkers reflecting treatment response and capable of predicting long-term outcomes are urgently needed.

Objectives: To develop a pharmacometric multistate model to evaluate the link between potential predictors and long-term outcomes.

Methods: Data were obtained from two Phase II clinical trials (TMC207-C208 and TMC207-C209) with bedaquiline on top of a multidrug background regimen. Patients were typically followed throughout a 24 week investigational treatment period plus a 96 week follow-up period. A five-state multistate model (active TB, converted, recurrent TB, dropout, and death) was developed to describe observed transitions. Evaluated predictors included patient characteristics, baseline TB disease severity and on-treatment biomarkers.

Results: A fast bacterial clearance in the first 2 weeks and low TB bacterial burden at baseline increased probability to achieve conversion, whereas patients with XDR-TB were less likely to reach conversion. Higher estimated mycobacterial load at the end of 24 week treatment increased the probability of recurrence. At 120 weeks, the model predicted 55% (95% prediction interval, 50%-60%), 6.5% (4.2%-9.0%) and 7.5% (5.2%-10%) of patients in converted, recurrent TB and death states, respectively. Simulations predicted a substantial increase of recurrence after 24 weeks in patients with slow bacterial clearance regardless of baseline bacterial burden.

Conclusions: The developed multistate model successfully described TB treatment outcomes. The multistate modelling framework enables prediction of several outcomes simultaneously, and allows mechanistically sound investigation of novel promising predictors. This may help support future biomarker evaluation, clinical trial design and analysis.

Background: Implementation level of long-acting injectable agents cabotegravir/rilpivirine (LAI CAB/RPV) for human immunodeficiency virus (HIV) treatment in Italy is still not known. The aim of this study is to identify the status of implementation of LAI CAB-RPV and its barriers.

Materials and methods: A cross-sectional online survey was conducted among infectious diseases (ID) physicians and nurses belonging to the ICONA network in Italy. Three validate 4-items measures were used: Acceptability of Intervention Measure (AIM), Intervention Appropriateness Measure (IAM) and Feasibility of Intervention Measure (FIM).

Results: Out of 61 ICONA centres, 38 (62%) completed the survey: 57.9% were academic centres, 42.1% were hospital-based. In total, 104 respondents were ID physicians (57.4%), 77 were nurses (42.5%); 4.5% of all PWH followed at the 38 centres started LAI CAB/RPV at time of study. Centres taking care of >1000 PWH reported 95% application of procedures for LA implementation, higher than other centres (P = 0.009). Mean score of AIM was (16.0, standard deviation, SD, 3.3), of IAM (16.0, SD 3.0) and FIM (16.0, SD 2.9). A linear correlation was found between AIM and the number of people with HIV who started LAI CAB/RPV (25-50 versus <25, coefficient of correlation [b] 2.57, 95%CI 0.91-4.60, P = 0.004), academic versus hospital-based centres (b -1.59, 95%CI -2.76-0.110044, P = 0.007) and the absence of preliminary systematic assessment of staff (b -1.98, 95%CI -3.31-0.65, P = 0.004). Implementation barriers were not significantly different according to the number of PWH/centre.

Conclusions: LAI CAB/RPV implementation was low, with a great variability according to centre size. Tailored and centre-specific interventions to address barriers and to optimize the LA treatment implementation should be designed.