Lesion viral burden, multidrug-resistant superinfection, and HIV-associated haematological vulnerability in hospitalised clade Ib mpox: a prospective cohort study in Uganda

Background Mpox has shifted to sustained human-to-human transmission across Africa, yet integrated triage incorporating viral burden, bacterial co-infection, antimicrobial resistance (AMR), HIV status, and routine biomarkers remain scarce. Methods At Uganda's national mpox referral hospital, we prospectively enrolled 155 adults at 14 ± 2 days post-symptom onset; mpox was confirmed by lesion-swab qPCR (F3L), with clade assignment by whole-genome sequencing in a prespecified subset (March–April 2025). Lesion viral DNA burden was estimated using qPCR cycle threshold (Ct) values. Purulent lesions underwent EUCAST-standardised culture and susceptibility testing. Routine laboratory assessments included complete blood counts, C-reactive protein, serum chemistries, HIV serostatus, and plasma HIV-1 RNA. Findings Median age was 30 years, and 73/155 (47%) had HIV infection. Multisite pain, particularly anogenital, was highly prevalent. Among 80 participants with purulent lesions selected for clinically suspected bacterial superinfection, all yielded bacterial growth; 35/80 (43.8%) were polymicrobial and predominantly multidrug-resistant Gram-negative bacilli. Susceptibility to first-line β-lactams and fluoroquinolones was low, whereas meropenem retained activity (51/61, 84%). Lesion viral burden did not differ by HIV serostatus and showed weak correlation with HIV-1 viraemia; higher burden was associated with leucocytosis, neutrophilia with left shift, elevated CRP, and hypoalbuminaemia. Genomes clustered within Clade Ib, without segregation by HIV status or clinical severity. Interpretation Hospitalised adults with acute Clade Ib mpox in Uganda exhibited high lesion viral burden, frequent multidrug-resistant bacterial co-isolation, and an inflammatory haematological profile accentuated in participants living with HIV-1. These findings support consideration of integrating diagnostic microbiology, HIV viral load assessment, and antimicrobial stewardship into mpox case-management in endemic settings. Funding This study was supported by the Coalition for Epidemic Preparedness Innovations (CEPI; Project ID PRJ-8284).