P-431. Mycobacterium abscessus Infection in Children - A 7 Year Experience in a Tertiary Paediatric Centre in Singapore

Abstract Background Mycobacterium abscessus is a fast-growing nontuberculous mycobacterium (NTM) and can lead to infections in both immunocompetent and immunocompromised children. Our study describes the clinical characteristics and treatment outcomes of M. abscessus infection in our population.Table 1:Summary of clinical characteristics, diagnosis, treatment and outcomes*antibiotics deemed not required after child underwent surgical procedure**includes removal of central lineTable 2:M. abscessus susceptibility**Clofazimine susceptibility testing not performed locally Methods From the laboratory database, we identified children aged 0-18 years with positive cultures for M. abscessus over a 7-year-period (2018-2024) at KK Women’s and Children’s Hospital, a tertiary paediatric hospital in tropical Singapore. Clinical and microbiological data were collected.Table 3:Adverse effects and treatment outcomes in children on clofazimine-based regimens*both had infected lines removed warranting no further treatment**includes removal of central line Results There were 41 children with M. abscessus infection. Median age was 7.3 years and 41.5% were males. Cervicofacial lymphadenitis was the most common clinical manifestation (n=25, 61.0%) followed by skin and soft tissue infections of the lower limbs (n=9, 21.9%) (Table 1). Median time to positive growth of M. abscessus on bacterial culture was significantly faster at 5 days compared to mycobacterial culture at 22.5 days (p< 0.001). The majority of the isolates were sensitive to amikacin (100%) and clarithromycin (79.5%) (Table 2). All macrolide-resistant isolates were subsp. abscessus. The most common treatment regime was the combination of a macrolide and clofazimine (68.3%). While clofazimine susceptibility was not performed locally, it was used based on 100% susceptibility from past publications. Side effects of Clofazamine were uncommon and not severe (Table 3). The median antimicrobial treatment duration was 6 months. Relapse was seen in 10 cases (24.4%); 7 (17.1%) at the same site and 3 (7.3%) at different sites. Patients with relapse received 2.6 more months of antibiotics on average compared to those without relapse (p = 0.01). Almost all (97.6%) patients required surgical procedures with 17 (41.5%) needing ≥2 surgeries. Complete resolution occurred in all patients and no mortality was observed. Conclusion Mycobacterium abscessus infections can be challenging to treat in children requiring multiple surgical procedures and prolonged antimicrobial treatment. Source control with targeted antimicrobial therapy can lead to excellent outcomes. Disclosures All Authors: No reported disclosures