Comparative Bactericidal Activity Of Representative ß-Lactams Against Enterobacterales, Acinetobacter Baumannii and Pseudomonas Aeruginosa

[Posted 25/May/2022]

AUDIENCE: Infectious Disease, Internal Medicine

KEY FINDINGS: ß-Lactam sub-classes (penicillins, cephalosporins, monobactams and carbapenems) have different antibacterial effects against E. coli, K. pneumoniae, A. baumannii and P. aeruginosa. Extrapolation of in vitro pharmacodynamic findings from one species to another or one sub-class of ß-lactam to another is not justified.

BACKGROUND: There is surprisingly little comparative published data on the bactericidal action of different sub-classes of ß-lactams against aerobic Gram-negative rods, and the assumption is that all behave in the same way. Purpose of this study is to describe a systematic investigation of a representative penicillin, cephalosporin, monobactam and carbapenem against Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa.

DETAILS: Concentration-time-kill curves (TKC) were determined for three strains each of E. coli, K. pneumoniae, A. baumannii and P. aeruginosa. All strains were susceptible to the agents used. The antibiotics were piperacillin/tazobactam, ceftazidime, aztreonam and meropenem. The initial inoculum was 106 cfu/mL and TKC were determined over 48 h. The area-under-the-bacterial-kill curve to 24 h (AUBKC 24 log cfu.h/mL) and 48 h (AUBKC 48) were used to measure antibacterial effect (ABE). Population profiles before and after antibiotic exposure were recorded. Against E. coli and K. pneumoniae meropenem had a maximal ABE at >=MIC x 1 concentrations while piperacillin/tazobactam and ceftazidime had maximal effect at >=MIC x 4 and aztreonam at >=MIC x 8 concentrations. Ceftazidime, aztreonam and meropenem had less ABE against K. pneumoniae than E. coli. Against P. aeruginosa, meropenem was most bactericidal, with a maximum ABE at 8x/16 x MIC. Other ß-lactams had notably less ABE. In contrast, against A. baumannii, ceftazidime and meropenem had the greatest ABE, with a maximal effect at >=MIC x 4, concentration changes in population profiles were least apparent with E. coli.

Copyright © Oxford University Press. All rights reserved.

Source: Noel, A. R., Attwood, M., Bowker, K. E., et al. (2022). Comparative Bactericidal Activity Of Representative ß-Lactams Against Enterobacterales, Acinetobacter Baumannii and Pseudomonas Aeruginosa. Journal of Antimicrobial Chemotherapy. 2022; 77(5): 1306-1312. Published: May, 2022. DOI: 10.1093/jac/dkac026.

A Retrospective Repeated Cross-Sectional Study

[Posted 3/Oct/2025]

AUDIENCE: Family Medicine, Infectious Disease

KEY FINDINGS: Medicare beneficiaries aged 65 years and older with HIV in the USA were more likely to receive opioid prescriptions and have OUD indicators than matched beneficiaries without HIV. Findings could help guide clinical opioid prescription guidelines and public health surveillance among this vulnerable ageing population.

BACKGROUND: There is longstanding concern that people with HIV receive prescription opioids at higher rates and have a disproportionate burden of opioid use disorder (OUD) compared with their counterparts without HIV. We aimed to evaluate trends of opioid prescriptions and indicators of OUD in an understudied but growing population of older adults with HIV.

DETAILS: For this retrospective repeated cross-sectional study, authors constructed annual cohorts through a nationally representative sample of fee-for-service Medicare beneficiaries aged 65 years and older in the USA with Part D coverage (ie, prescription drug) enrolled between Jan 1, 2008, and Dec 31, 2021. Beneficiaries were eligible for inclusion in each cross-sectional cohort if they had reached the age of 65 years by Jan 1 of the calendar year and had 1 year of continuous Medicare enrolment in Part A (inpatient hospital care), B (outpatient care), and D. Beneficiaries with HIV were matched in a 1:3 ratio to beneficiaries without HIV on age, sex, race or ethnicity, US state, and dual eligibility status (Medicare and Medicaid). The main outcomes were receipt of at least one opioid prescription and any indicator of OUD (ie, formal diagnosis, medication for OUD, or opioid-related or emergency department visits) during each calendar year. Generalised estimating equations were used to estimate odds ratios (ORs) of each outcome, comparing matched beneficiaries with or without HIV. Due to data availability, our analysis of indicators of OUD was restricted to 2008-16. Across all years, 163,429 beneficiaries with HIV and 490,287 beneficiaries without HIV were included (475,516 [72.7%] were male, 178,200 [27.3%] were female; 305,776 [46.8%] were non-Hispanic White, 238,172 [36.4%] were Black [or African American], 84,128 [12.9%] were Hispanic, 8964 [1.4%] were Asian or Pacific Islander, and 16,676 [2.6%] were other races or ethnicities). During 2008-21, 57,373 (35.1%) of 163,429 people with HIV and 138,547 (28.3%) of 490,287 people without HIV received at least one opioid prescription. During 2008-16, 2408 (3.1%) of 76,637 people with HIV and 2831 (1.2%) of 229,911 people without HIV had any indicator of OUD. Across all analysed years, beneficiaries with HIV had significantly increased odds of receiving at least one opioid prescription (OR 1.38, 95% CI 1.36-1.39) and having indicators of OUD (2.61, 2.47-2.76) compared with their matched counterparts without HIV.

Copyright © The Author(s). Elsevier Ltd. All rights reserved.

Source: Shiau, S., Drago, F., Kinkade, C. W., et al. (2024). Prescription Opioid Use and Opioid Use Disorder Among Older Adults With HIV in the USA From 2008 to 2021: A Retrospective Repeated Cross-Sectional Study. The Lancet Primary Care. 2025; 1(3): 100017. Published: September, 2025. DOI: 10.1016/j.lanprc.2025.100017.

[Posted 28/Aug/2025]

AUDIENCE: Neurology, Pediatric, Neurosurgery

KEY FINDINGS: Infants up to 6 weeks of age with genetically diagnosed SMA who were treated with risdiplam before the development of clinical signs or symptoms appeared to have better functional and survival outcomes at 12 and 24 months than untreated infants in natural history studies. Larger, controlled studies with longer follow-up are needed to further understand the relative efficacy and safety of presymptomatic treatment of SMA with risdiplam.

BACKGROUND: Risdiplam, an oral pre–messenger RNA splicing modifier, is an efficacious treatment for persons with symptomatic spinal muscular atrophy (SMA). The safety and efficacy of risdiplam in presymptomatic disease are unclear.

DETAILS: Authors conducted an open-label study of daily oral risdiplam (with the dose adjusted to 0.2 mg per kilogram of body weight) in infants 1 day (birth) to 42 days of age with genetically diagnosed SMA but without strongly suggestive clinical signs or symptoms. The primary outcome, assessed in infants with two SMN2 copies and a baseline ulnar compound muscle action potential (CMAP) amplitude of at least 1.5 mV, was the ability to sit without support at month 12. Natural history studies have shown that the majority of infants with two SMN2 copies who are untreated would have a severe SMA phenotype (type 1), would never sit independently, would receive permanent ventilation and feeding support, or would die by 13 months of age. Secondary outcomes that were assessed over a period of 24 months included survival, ventilatory support, motor milestones, the development of clinically manifested SMA, feeding, and growth. A total of 26 infants with two, three, or four or more copies of SMN2 were enrolled. After 12 months of treatment, 21 infants (81%) could sit unsupported for 30 seconds, 14 (54%) could stand alone, and 11 (42%) could walk alone. A total of 4 of 5 infants (80%; 95% confidence interval, 28 to 100) with two SMN2 copies and a baseline ulnar CMAP amplitude of at least 1.5 mV were able to sit without support for at least 5 seconds. Three infants were withdrawn from the study by a parent or caregiver after the month 12 visit. Of 23 infants who completed 24 months of treatment, all were alive without the use of permanent ventilation or feeding support. Over a period of 24 months, nine treatment-related adverse events were reported in 7 infants; none of these events were serious.

Copyright © Massachusetts Medical Society. All rights reserved.

Source: Finkel, R. S., Servais, L., Vlodavets, D., et al. (2024). Risdiplam in Presymptomatic Spinal Muscular Atrophy. N Engl J Med. 2025; 393(7): 671-682. Published: August 13, 2025. DOI: 10.1056/NEJMoa2410120.

[Posted 22/Aug/2025]

AUDIENCE: All Healthcare Professionals

KEY FINDINGS:

BACKGROUND: Recurrent Respiratory Papillomatosis (RRP) is a rare and chronic condition caused by human papillomavirus (HPV) types 6 and 11. The disease leads to the formation of benign tumors in the respiratory tract, most often in the larynx, which can cause significant symptoms like voice changes and difficulty breathing. Historically, the primary treatment for RRP has been repeated surgical removal of the tumors, as there have been no approved medical therapies to address the underlying cause.

DETAILS: The U.S. Food and Drug Administration (FDA) has approved Papzimeos (zopapogene imadenovec-drba), a groundbreaking immunotherapy, for the treatment of adult patients with RRP. This therapy is a non-replicating adenoviral vector that works by stimulating a targeted immune response against the HPV-infected cells. It is administered via a subcutaneous injection and represents the first non-surgical therapeutic option for this rare disease, offering a new approach beyond traditional surgical management.

The approval of Papzimeos was based on data from a single-arm, open-label trial. The study demonstrated that 51.4% of patients who received the treatment achieved a complete response, defined as not needing any further surgical intervention for 12 months following the treatment. The clinical benefits were shown to be durable for most patients over a two-year period and correlated with the development of specific T-cells targeting HPV 6 and 11. The therapy had a favorable safety profile with no serious treatment-related adverse events.

Key information:

• First-of-its-kind Approval: Papzimeos is the first approved medical therapy for RRP.
• Novel Mechanism: It is an immunotherapy that targets the root cause of the disease, HPV-infected cells.
• Approval Pathway: The product received Orphan Drug and Breakthrough Therapy designations and was approved under Priority Review, reflecting the significant unmet medical need for RRP patients.

Source: FDA Approves First Immunotherapy for Recurrent Respiratory Papillomatosis. FDA. 2025; Published: August 14, 2025.

[Posted 21/Aug/2025]

AUDIENCE: Infectious Disease, Family Medicine

KEY FINDINGS: Authors first revealed the plasma metabolomic characteristics of H7N9 patients and found that a machine-learning model based on plasma metabolites could predict the risk of death for H7N9 in the early stage of admission.

BACKGROUND: Avian influenza such as H7N9 is currently a major global public health risk, and at present, there is a lack of relevant diagnostic and treatment markers.

DETAILS: Authors collected plasma samples from 104 confirmed H7N9 patients, 31 of whom died. Plasma metabolites were detected by UHPLC-HRMS, and a survival prediction model based on metabolites was constructed by machine-learning models. A total of 1536 metabolites were identified in the plasma samples of H7N9 patients, of which 64 metabolites were up-regulated and 35 metabolites were down-regulated in the death group. The enrichment analysis of tryptophan metabolism, porphyrin metabolism, and riboflavin metabolism were significantly up-regulated in the death group. We found that most lipids and lipid–like molecules were down-regulated in the death group, and organoheterocyclic compounds were significantly up-regulated in the death group. A machine-learning model was constructed for predicting mortality based on porphobilinogen, 5-hydroxyindole-3-acetic acid, L-kynurenine, Biliverdin, and D-dimer. The AUC on the test set was 0.929.

Copyright © The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. All rights reserved.

Source: Wang, Y., Ni, J., Huanga, M., et al. Metabolomic Profiling of Plasma Reveals Differential Disease Severity Markers in Avian Influenza A(H7N9) Infection Patients. International Journal of Infectious Diseases. 2025; 158: 107957. Published: September, 2025. DOI: 10.1016/j.ijid.2025.107957.

Immunogenicity, Safety, and Efficacy of the Vaccine H56:IC31 In Reducing the Rate of Tuberculosis Disease Recurrence In HIV-negative Adults Successfully Treated for Drug-Susceptible Pulmonary Tuberculosis: A Double-Blind, Randomised, Placebo-Controlled, Phase 2b Trial

[Posted 2/Jul/2025]

AUDIENCE: Infectious Disease, Family Medicine

KEY FINDINGS: Vaccination with H56:IC31 at treatment completion for pulmonary tuberculosis did not reduce the risk of recurrent disease. H56:IC31 was well tolerated and immunogenic but might have increased the risk of relapses by endogenous strains.

BACKGROUND: People with tuberculosis who complete treatment remain at risk of recurrent disease. The vaccine H56:IC31 has been shown to be safe and immunogenic in phase 1 and 2 studies, but whether it can reduce the risk of tuberculosis recurrence is unknown.

DETAILS: In a double-blind, randomised, placebo-controlled, phase 2b trial in South Africa (five clinical trial sites) and Tanzania (one clinical trial site), we enrolled participants aged 18-60 years, without HIV, who had completed more than 5 months (22 weeks) of treatment for drug-susceptible pulmonary tuberculosis. During trial screening (<=7 days after starting treatment), two sputum samples were obtained and frozen for later comparison to recurrent isolates by whole-genome sequencing (WGS). Eligible participants were randomly assigned (1:1; block size of four) to receive two intramuscular doses in the deltoid, 56 days apart, of H56:IC31 or placebo. After the first dose of H56:IC31 or placebo, participants were followed up until study day 421 (1 year after the second dose) and checked at each visit for tuberculosis signs and symptoms. If tuberculosis was suspected, two sputum samples were obtained: one sample was tested by automated molecular test (Xpert MTB/RIF Ultra) and sent for liquid culture; and the other sample was stored frozen for later analysis by whole-genome sequencing (WGS). At the last visit (day 421), two sputum samples were obtained from all sputum-productive participants, regardless of symptoms, to detect cases of asymptomatic tuberculosis. The primary endpoint was culture-confirmed recurrent pulmonary tuberculosis (due to relapse with the same strain, reinfection by a different strain, or indeterminate) occuring during the period starting at day 70 (14 days after the second dose) and ending on day 421 (1 year after the second dose). Vaccine efficacy against recurrent tuberculosis was derived from Cox proportional hazards models. Secondary endpoints included vaccine efficacy to prevent tuberculosis relapse or reinfection independently, as differentiated by WGS, and safety and immunogenicity outcomes (H56-specific CD4 T-cell responses and humoral anti-H56 IgG responses). Primary analysis of vaccine efficacy was based on modified intention-to-treat (mITT), in all randomly assigned participants except those with tuberculosis disease recurrence or who withdrew before day 70 (or 14 days after the second dose for those who received both doses). Safety was assessed in all randomly assigned participants who received at least one dose of vaccine or placebo. The trial was registered with ClinicalTrials.gov, NCT03512249, and is complete. 831 participants (mean age 34.7 years [SD 11.1]; 229 [28%] female and 602 [72%] male; 549 [66%] Black) were enrolled from Jan 31, 2019, to Jan 20, 2022; 415 participants were randomly assigned to receive H56:IC31 and 416 to receive placebo. Follow-up was completed by March 20, 2023 (mean follow-up duration 410.1 days [SD 82.8]). In the primary mITT analysis, recurrent tuberculosis occurred in 23 of 400 participants in the H56:IC31 group (12 relapses, eight reinfections, and three indeterminate); and in 14 of 406 in the placebo group (six relapses, seven reinfections, and one indeterminate). Vaccine efficacy for prevention of recurrence was -73.8% (95% CI -246.9 to 9.8; p=0.10). Vaccine efficacy for prevention of relapse was -116.1% (-522.2 to 16.3; p=0.11) and for prevention of reinfection was -21.1% (-245.3 to 56.5; p=0.71). 2 weeks after the planned second dose, H56:IC31 had significantly increased the frequencies of H56-specific CD4 T cells expressing interferon-γ, tumour necrosis factor, interleukin (IL)-2, or IL-17 in vaccinees (median percentage of CD4 T cells, 0.35% [IQR 0.19 to 0.57]) compared with placebo (0.11% [0.09 to 0.23]; p < 0.0001). H56-specific IgG responses were significantly higher in H56:IC31 recipients (median arbitrary units per mL, 6.84 [IQR 1.64 to 32.8]) than in placebo recipients (1.94 [1.05 to 3.86]; p < 0.0001). A greater proportion of H56:IC31 recipients had mild-to-moderate injection site reactions than placebo recipients (165 [40%] of 415 vs 78 [19%] of 416). No treatment-related serious adverse events were reported. Two participants who received H56:IC31 and six who received placebo died.

Copyright © Elsevier Ltd. All rights reserved.

Source: Borges, A. H., Russell, M., Tait, D., et al. Immunogenicity, Safety, and Efficacy of the Vaccine H56:IC31 In Reducing the Rate of Tuberculosis Disease Recurrence In HIV-negative Adults Successfully Treated for Drug-Susceptible Pulmonary Tuberculosis: A Double-Blind, Randomised, Placebo-Controlled, Phase 2b Trial. The Lancet Infectious Diseases. 2025; 25(7): 751-763. Published: July, 2025. DOI: 10.1016/S1473-3099(24)00814-4.