Journal of Antimicrobial Chemotherapy最新文献

Background: The rising prevalence of pretreatment drug resistance (PDR) to non-nucleoside reverse-transcriptase inhibitors threatens the effectiveness of ART. In response, the WHO recommends dolutegravir-based ART regimens due to their high genetic barrier to resistance and better treatment outcomes. This is expected to contribute to achieving the Joint United Nations Programme on HIV/AIDS (UNAIDS) target of 95% viral suppression in people on ART.

Objectives: To estimate the prevalence of PDR among adults initiating ART and assess viral suppression and acquired HIV drug resistance (ADR) among individuals receiving ART in Belize.

Patients and methods: Nationally representative cross-sectional PDR and ADR surveys were conducted between 2021 and 2022. Sixty-seven adults were included in the PDR survey, and 43 children and adolescents and 331 adults were included in the ADR survey. Demographic and clinic data and blood specimens were collected. HIV drug resistance (HIVDR) was predicted using the Stanford HIVdb tool.

Results: The prevalence of PDR to efavirenz or nevirapine in adults was 49.3% (95% CI 42.2%-56.4%) and was significantly higher in those with previous antiretroviral exposure (OR: 7.16; 95% CI 2.71-18.95; P = 0.002). Among children and adolescents receiving ART, 50.0% had viral suppression, with better rates for those receiving dolutegravir-based ART (OR: 5.31; 95% CI 3.02-9.34; P < 0.001). In adults, 79.6% achieved viral suppression. No resistance to integrase inhibitors was observed in those on dolutegravir-based ART.

Conclusions: Prioritizing dolutegravir-based ART is critical for achieving HIV epidemic control in Belize. Efforts should focus on retention in care and adherence support to prevent HIVDR.

Background: In the preclinical development of new drugs, animal models are often employed to predict their efficacy in humans, relying on translational pharmacokinetic/pharmacodynamic (PK/PD) studies. We performed in vitro experiments focusing on the comparison of plasma protein binding (PPB) and bacterial growth dynamics of clindamycin, a commonly used antimicrobial agent, across a range of drug concentrations and plasma environments.

Methods: Human, bovine and rat plasma were used for determining PPB of clindamycin at various antibiotic concentrations in buffer and media containing 20% to 70% plasma or pure plasma using ultrafiltration (UF) and equilibrium dialysis (ED). Also bacterial growth and time-kill assays were performed in Mueller-Hinton broth (MHB) containing various percentages of plasma.

Results: Protein binding of clindamycin correlated well between UF and ED. Notably, clindamycin exhibited substantially lower protein binding to rat plasma compared with human and bovine plasma. Staphylococcus aureus growth was significantly reduced in 70% human, bovine, and rat plasma after 4, 8 and 24 h compared with standard MHB. Time-kill data demonstrated that bacterial counts at both 20% and 70% plasmas were less when compared with MHB at drug concentrations lower than MIC after 4 and 8 h of incubation. For rat plasma, the difference was maintained over 24 h of incubation. Furthermore, a complete bacterial killing at 16 mg/L was observed after 24 h in 20% and 70% human and bovine plasma, but not for rat plasma.

Conclusions: Recognizing interspecies differences in PB might be essential for optimizing the translational relevance of preclinical studies.

Background: Variations in neonatal aciclovir prescribing for suspected herpes simplex virus (HSV) disease are well-known, but there are limited data describing aciclovir prescribing in older children.

Methods: Medical records of neonates (≤28 days) and children (29 days to 18 years) prescribed intravenous aciclovir for suspected HSV disease (1 January 2019-12 December 2019) in eight Australian and New Zealand hospitals were reviewed. Prescribing indication, HSV testing, aciclovir prescription details, adverse events and discharge diagnosis were recorded.

Results: 1426 received empirical aciclovir. For neonates (n = 425), the median duration was 1 day (IQR 1-3), 411/425 underwent HSV investigations and 13/425 had HSV disease (two with disseminated encephalitis, four with encephalitis and seven with skin, eye, mouth disease). Of the 1001 children, 906 were immunocompetent. 136/906 suspected of mucocutaneous disease received aciclovir for a median of 2 days (1-2), 121/136 underwent HSV testing, and 69/136 had proven disease. 770/906 received aciclovir for suspected disseminated disease or encephalitis for a median of 1 day (1-2), 556/770 underwent HSV testing, and 5/770 had disseminated disease or encephalitis. Among 95 immunocompromised children, 53/58 with suspected mucocutaneous disease had HSV testing and this was confirmed in 22. Disseminated disease or encephalitis was suspected in 37/95, HSV testing conducted in 23/37 and detected in one. The median aciclovir duration was 3 (2-7) days for immunocompromised children. Nephrotoxicity occurred in 7/1426 and 24/1426 had an extravasation injury.

Conclusion: Frequent and often unnecessary intravenous aciclovir prescribing for suspected HSV encephalitis or disseminated disease occurred in children, as evidenced by incomplete HSV investigations and only 5/770 older children having the diagnosis confirmed.

Objective: Five Phase 3 bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) clinical studies demonstrated that the efficacy of B/F/TAF was non-inferior to dolutegravir (DTG) + 2 NRTIs. We retrospectively assessed drug adherence and effect on virologic outcomes.

Methods: Studies (NCT02607930, NCT02607956, NCT03547908, NCT02603120 and NCT03110380) were double-blind, placebo-controlled and enrolled treatment-naïve or virologically suppressed adults. Adherence was calculated by pill count from returned pill bottles; virologic outcome was assessed by last on-treatment HIV-1 RNA.

Results: Altogether, 2622 participants (B/F/TAF: n = 1306; DTG + 2 NRTIs: n = 1316) were categorized as having high (≥95%), intermediate (≥85% to <95%) or low (<85%) adherence. Through Week 48, low adherence was observed in 46 (3.5%) participants in the B/F/TAF group (78% median adherence) and 69 (5.2%) in the DTG + 2 NRTI group (80% median adherence). Overall, 1287 (98.5%) participants in the B/F/TAF group and 1292 (98.2%) in the DTG + 2 NRTI group had virologic suppression (VS; HIV-1 RNA < 50 copies/mL) through Week 48. VS in participants with low adherence versus high or intermediate adherence was similar in the B/F/TAF group, but lower in the DTG + 2 NRTI group (P ≤ 0.002). Similar results were observed at Weeks 96 and 144. Two participants (<95% adherence) in the DTG + 2 NRTI group receiving DTG and abacavir/lamivudine developed M184V; there was no treatment-emergent resistance to B/F/TAF.

Conclusions: Participants with suboptimal (<85%) adherence to B/F/TAF maintained high levels of VS, whereas suboptimal DTG + 2 NRTI adherence was associated with lower VS.

Objectives: The use of mouse models of complicated urinary tract infection (cUTI) has usually been limited to a single timepoint assessment of bacterial burden. Based on longitudinal in vitro and in vivo data, we developed a pharmacokinetic-pharmacodynamic (PKPD) model to assess the efficacy of apramycin, a broad-spectrum aminoglycoside antibiotic, in mouse models of cUTI.

Methods: Two Escherichia coli strains were studied (EN591 and ATCC 700336). Apramycin exposure-effect relationships were established with in vitro time-kill data at pH 6 and pH 7.4 and in mice with cUTI. Immunocompetent mice were treated with apramycin (1.5-30 mg/kg) starting 24 h post-infection. Kidney and bladder tissue were collected 6-96 h post-infection for cfu determination. A PKPD model integrating all data was developed and simulations were performed to predict bacterial burden in humans.

Results: Treatment with apramycin reduced the bacterial load in kidneys and bladder tissue up to 4.3-log compared with vehicle control. In vitro and in vivo tissue time-course efficacy data were integrated into the PKPD model, showing 76%-98% reduction of bacterial net growth and 3- to 145-fold increase in apramycin potency in vivo compared with in vitro. Simulations suggested that an 11 mg/kg daily dose would be sufficient to achieve bacterial stasis in kidneys and bladder in humans.

Conclusions: PKPD modelling with in vitro and in vivo PK and PD data enabled simultaneous evaluation of the different components that influence drug effect, an approach that had not yet been evaluated for antibiotics in the cUTI model and that has potential to enhance model-informed drug development of antibiotics.

Objectives: In England, group B streptococci (GBS; Streptococcus agalactiae) are considered universally susceptible to penicillin. Reports from Africa, Asia, North America and a few European countries have described GBS isolates with penicillin MICs above the epidemiological cut-off (0.125 mg/L). Our aim was to characterize a penicillin-resistant GBS (PRGBS) isolate recovered in 2016 from a patient treated with long-term antimicrobials in the UK.

Methods: Antibiotic susceptibility of a referred isolate from a discharging sinus overlying a chronic prosthetic joint infection was determined using gradient strip testing for seven antibiotics. Illumina short read sequencing was carried out using a HiSeq 2500 platform to determine MLST, capsular type, to detect mutations in the pbp genes, and to compare the isolate with contemporaneous GBS isolates circulating in the UK.

Results: The GBS isolate belonged to capsular type Ia and MLST 144. We observed resistance to penicillin (MIC = 1 mg/L) and tetracycline (32 mg/L) with susceptibility to linezolid (1 mg/L), erythromycin (0.064 mg/L), clindamycin (0.064 mg/L), teicoplanin (0.064 mg/L) and vancomycin (0.25 mg/L). Deduced amino acid sequences revealed substitutions and non-synonymous changes in PBP2x and PBP2b. Genomic analysis of contemporaneous cases (n = 34) from across the UK identified single nucleotide polymorphism (SNP) variation ranged from 153-6596 SNPs.

Conclusions: We confirm the first identification of a PRGBS isolate amongst referrals to the UK's national reference laboratory. Substitutions in pbp1a, pbp2a, pbp2x and pbp2b were identified that likely developed in the face of long-term beta-lactam antibiotic use.

Objectives: The objective of this study was to identify and analyse the distribution characteristics, toxin genotyping and antimicrobial susceptibility of Clostridium perfringens and to investigate its resistance mechanisms and genetic characteristics.

Methods: The MICs of various antibiotics against C. perfringens were determined using the agar dilution method, and resistance genes and toxin genotypes were detected by PCR. Genetic relationships were analysed using MLST. WGS was conducted on the DNB system and PacBio platforms.

Results: Analysis of 36 strains of C. perfringens revealed that the major toxin types were types C and F, with 86.1% of the strains isolated from bile samples. Of these, 30.6% of the strains exhibited MDR, with resistance rates of 75.0%, 52.8% and 52.8% for penicillin, clindamycin and ampicillin, respectively; however, no resistance to metronidazole and carbapenems was observed. MLST analysis identified 29 STs, including 14 novel types. ST221 and ST498 were the dominant types. The WGS revealed that the most prevalent virulence factors are plc (100.0%), nagH (100.0%), colA (100.0%), nanJ (100.0%), entB (100%), nanH (97.0%), entA (97.0%) and nanI (90.9%). Among these factors, the primary determinants of tetracycline resistance are tetA (66.7%) and tetB (78.8%), which represent the most frequently detected antibiotic resistance genes.

Conclusions: This study indicates that the infection rate of C. perfringens is relatively high, with the majority of isolated strains exhibiting MDR. The observed high levels of antibiotic resistance, combined with the significant genetic diversity of these strains, suggest a potential public health risk.

Background: Scedosporium/Lomentospora species are ranked as the second most frequently isolated filamentous fungi from cystic fibrosis (CF) patients. Previously, we demonstrated that the minimum inhibitory concentration (MIC) for voriconazole and posaconazole increased when performed on a mucin-containing synthetic CF sputum medium (SCFM) compared to the standard medium, RPMI-1640. In this study, we have expanded the MIC comparison to four additional azoles and investigated characteristics linked to azole resistance in Scedosporium apiospermum, Scedosporium minutisporum, Scedosporium aurantiacum and Lomentospora prolificans.

Methods: MIC was assayed by CLSI protocol, efflux pump activity was assessed by rhodamine 6G and sterols were analysed by gas chromatography-mass spectrometry (GC-MS).

Results: Overall, MICs for fluconazole, itraconazole, voriconazole, posaconazole, miconazole and ketoconazole increased by least 2-fold when susceptibility tests were performed using SCFM compared to RPMI. The activity of efflux pumps was similar in both media; however, in RPMI, but not in SCFM, the activity was induced by voriconazole and fluconazole. Additionally, MICs for those antifungals decreased more noticeably in SCFM than in RPMI in the presence of the efflux pump inhibitor PaβN. The SCFM-grown cells presented fewer sterols in their composition, and consequently higher membrane fluidity, than RPMI-grown cells. GC-MS analysis demonstrated a remodulation in the sterol profile in SCFM- compared to RPMI-grown cells. Accordingly, when the MIC assay was performed in the presence of the membrane stressor NaCl (3%), the susceptibility to voriconazole and fluconazole increased more in SCFM- than RPMI-grown cells.

Conclusions: Scedosporium/Lomentospora species undergo cellular adaptations in SCFM that favours their growth in face of the challenges imposed by azole antifungals.

Objectives: To evaluate clinical impact of ceftazidime/avibactam on treating infections due to MDR Gram-negative bacteria in patients with haematological malignancies (HMs).

Methods: We conducted a retrospective, observational study at 17 Italian haematological wards that included patients with HMs receiving ceftazidime/avibactam for the treatment of suspected or proven infections. The primary endpoint was all-cause mortality 30 days after infection onset. Secondary endpoints included the development of in vitro ceftazidime/avibactam resistance, adverse reactions and infection relapse.

Results: Of 198 patients enrolled, 66 had fever of unknown origin and 132 had microbiologically proven infections (MPIs). Enterobacterales were responsible for 98 MPIs, with KPC producers accounting for 75% of these, and carbapenem-resistant Pseudomonas aeruginosa caused 25% of MPIs. The overall 30-day mortality rate was 17.7%. Infection relapse occurred in four patients with MPI. Patients who died within 30 days of infection onset tended to have pre-existing cerebrovascular diseases, a Charlson Comorbidity Index > 4 and septic shock at infection onset and had received inadequate initial antibiotic therapy. Thirty-day mortality was independently associated with septic shock at infection onset and inappropriate initial antibiotic therapy.

Conclusions: Our study provides further evidence about the effectiveness of ceftazidime/avibactam in treating infections in patients with HMs.