Lupe Isaia

University of Otago

 A load of CRAb – Undetected outbreaks of Carbapenem-resistant Acinetobacter baumannii in Samoa and links to other Pacific Islands

Carbapenem-resistant Acinetobacter baumannii (CR-Ab) is a critical pathogen that has become increasingly prevalent in clinical settings and difficult to treat due to its multidrug resistance (MDR). Using whole-genome sequencing (WGS), we report an undetected and prolonged outbreak of CR-Ab within the Tupua Tamasese Mea’ole Hospital (TTMH) in Samoa.  25 CR-Ab were collected between November 2017 and January 2020, from the TTMH Laboratory and from Middlemore Hospital (MMH) in New Zealand. Samples were isolated from blood, wound swabs, urine, sputum and screening swabs. All isolates belonged to sequence type (ST) 1050, and carbapenem resistance was due to acquired class D carbapenemase blaOXA-23 in addition to the intrinsic blaOXA-66. We demonstrated minimal genetic diversification between isolates, with ≤9 single nucleotide polymorphisms (SNPs) differences in the core genome from the earliest case (WS003, November 2017 from TTMH). Two isolates from patients in emergency and two from Intensive Care were identical having no SNP differences over 10 months, suggesting CR-Ab may not be limited to the hospital settings. Carriage of CR-Ab ST1050 was observed in two isolates from MMH, which varied from WS003 by 5 (January-2020) and 7 SNPs (February-2019) respectively. These results show clear linkages of CR-Ab strains from Samoa to MMH in New Zealand.  Furthermore, CR-Ab isolates from Samoa shared a common ancestor with CR-Ab strains isolated from a Brisbane Hospital outbreak that started in 2016 and continued until 2018. All CR-Ab isolates from Samoa differed by ≤14 SNPs when compared to the index patient from the outbreak in Brisbane.

These results are critical in informing infection control practises to prevent further spread of this critical pathogen within TTMH and within the Pacific.

Lupe worked for 10 years as a medical laboratory scientist in the Clinical Laboratory within the Tupua Tamasese Mea’ole Hospital, Samoa. She has a Bachelor of Medical Science and Master of Science in Medicine (Infection and Immunity) from the University of Sydney, Australia. She is a recipient of the University of Otago Pacific Doctoral Scholarship and currently in her final year of studies. Her research is focused on antibiotic resistance genes in clinical isolates from Samoa, and their phylogenetic relationships to critical pathogens isolated from Samoans in Auckland, New Zealand.


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