The burden of antimicrobial resistance in coagulase-negative staphylococci from neonates in low-income countries

Aziz, Jawaria 2026. The burden of antimicrobial resistance in coagulase-negative staphylococci from neonates in low-income countries. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Coagulase-negative staphylococci (CoNS), once largely dismissed as contaminants, are now recognised as major opportunistic pathogens of neonatal sepsis. Their capacity to form biofilms and acquire antimicrobial resistance determinants has enhanced their persistence in NICUs. BARNARDS-II was undertaken in 13 sites across Pakistan, Nigeria and Bangladesh, analysing sepsis rates in neonates (0-28 days of life). Neonates with suspected sepsis were enrolled; clinical and epidemiological data were input into REDCap. Minimum inhibitory concentration and whole-genome sequencing were performed. Over 15 CoNS species were identified from blood cultures, with S. haemolyticus, S. epidermidis and S. hominis being the most prevalent, with variable regional aetiology. S. haemolyticus and M. sciuri (EOS) were prominent in Pakistan, and S. epidermidis and S. hominis (LOS) were in Nigeria. Higher levels of AMR were seen against multiple antibiotics, with 83% resistance to gentamicin and 93% MDR in S. haemolyticus. Higher mecA carriage and elevated MICs to cefoxitin (resistant to ampicillin/β-lactam/penicillins) covered empiric treatment for neonatal sepsis recommended by WHO, followed in the absence of local infrastructure for accurate identification of sepsis-causing staphylococci. There was higher resistance in isolates from Pakistan than in Nigeria, so defining an empirical therapy by country may be a better approach. A clonal ST82 M. sciuri outbreak was identified in PIMS in 2017-2018 (BARNARDS-I, Pakistan); no CoNS outbreaks were found in any of the sites for BARNARDS-II. S. haemolyticus ST3 is a strong candidate for an ancestral lineage associated with the isolates identified in Pakistan and Nigeria. Still, evidence of dynamic localised microevolution is evident, showing higher diversity relative to other CoNS isolated in BARNARDS-II. S. haemolyticus was found to be more virulent in Galleria modelling, compared to other CoNS species. For S. epidermidis, ST2 appears to be the dominant sequence type. S. epidermidis was found to generate much denser and more robust biofilms compared to other CoNS species.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Medicine
Date of First Compliant Deposit:	22 October 2026
Last Modified:	23 Oct 2026 15:47
URI:	https://orca.cardiff.ac.uk/id/eprint/190383

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