Bungsu et al Brunei International Medical Journal 2025;21:82-87 Brunei International Medical Journal Brunei Colorectal Cancer Awareness and Risk Education for Screening (Bru-CARES) Community Project N BUNGSU1, AS HAJI MD ALI1, A HAJI GHAZALI1, S KONG1, MK ABU BAKAR1, NA GULZAR AHMAD1, S SUHAILI1, SK ONG1,2, P HASHMET1,3, VH CHONG1,2, K KOK1, E ERDAL1, H GHANI1*

Nosocomial infection caused by Acinetobacter baumannii is common among immunocompromised patients. Treatment strategy is limited due to rapid resistance development and lack of novel antibiotic. Colistin has been the last line therapy with good in vitro activity against infections caused by multi-drug resistance A. baumannii. However, pharmacological updates are required to support dosing optimisation. This study aimed to determine the time-kill kinetic and resistance development after antibiotic exposure as well as post-antibiotic effect of colistin at different static concentrations in in vitro A. baumannii system. The static in vitro time-kill and post-antibiotic effect experiments were conducted against two clinical isolates as well as one reference isolate ATCC 19606. Time-kill and postantibiotic effect were studied at colistin concentrations ranging from 0.25MIC to 16.0MIC and 0.5MIC to 4.0MIC, respectively. Post-exposure resistance development was examined in time-kill study. Killing activity and post-antibiotic effect were in a concentration-dependent manner. However, delayed killing activity indicates colistin tolerance. Development of resistance after exposure was not detected except for the ATCC 19606 strain. Dosing suggestion based on the observations include administration of supplemental dose 3 MIU at 12 hours after loading dose, administration of maintenance dose 9 MIU in two divided doses and application of extended interval in renal adjustment dose. However, the information is applicable for non-colistin-heteroresistance A. baumannii with colistin MIC < 1.0 mg/L. As for heteroresistance and strain with colistin MIC > 1.0 mg/L, combination therapy would be the more appropriate treatment strategy.

Acute sinusitis is most often a mild self-limiting disease. However, it may progress into severe and life threatening complications. One of the commonest being orbital complication of which visual loss is a direct consequence. In this 10 year retrospective study, the nature of orbital complication, clinical presentation and treatment modalities and outcome seen in children with acute sinusitis in a tertiary referral institute were reviewed. Of six patients, there was a case of preseptal cellulitis, 4 cases of subperiosteal abscess and one case of orbital abscess. Periorbital swelling was a common presenting feature. In 5 cases this was associated with proptosis with one case of impending optic nerve compression. The value of computed tomography and opthalmological examination as a component in the management plan is highlighted. All patients were treated with intravenous antibiotics but evidence of abscess collection warranted urgent surgical drainage in 5 patients, 3 being endoscopic drainage while external approach was done for the remaining 2 patients. Thus a child exhibiting orbital complication of acute sinusitis, prompt diagnosis and treatment is essential in obtaining the best outcome for the child.