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Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape
Hendricks, T. 2025. Assessment of Bacteriological and Immunological Markers Associated with Coagulase-Negative Staphylococci (CoNS) in Neonates at Tygerberg Hospital, Western Cape. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/...
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613775462400000 |
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| access_status_str | Open Access |
| author | Hendricks, Tharwat |
| author2 | Matukane, Siphiwe Ruthy |
| author_browse | Hendricks, Tharwat Matukane, Siphiwe Ruthy |
| author_facet | Matukane, Siphiwe Ruthy Hendricks, Tharwat |
| author_sort | Hendricks, Tharwat |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Hendricks, T. 2025. Assessment of Bacteriological and Immunological Markers Associated with Coagulase-Negative Staphylococci (CoNS) in Neonates at Tygerberg Hospital, Western Cape. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/1c9541b3-1254-41bf-8107-0a548a33662b |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132415 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:41:30.564Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132415 Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape Hendricks, Tharwat Matukane, Siphiwe Ruthy Glashoff, Richard Helmuth Stellenbosch University. Faculty of Science. Dept. of Pathology. Medical Microbiology. Biochemical markers Neonatal infections -- Immunological aspects Staphylococcal infections Septicemia in children UCTD Hendricks, T. 2025. Assessment of Bacteriological and Immunological Markers Associated with Coagulase-Negative Staphylococci (CoNS) in Neonates at Tygerberg Hospital, Western Cape. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/1c9541b3-1254-41bf-8107-0a548a33662b Thesis (MSc)--Stellenbosch University, 2025. ENGLISH ABSTRACT: Introduction: Coagulase-Negative Staphylococci (CoNS) are commonly isolated from neonatal sepsis cases. However, CoNS isolation can indicate either causation or specimen contamination as these organisms are naturally present on human skin. Several bacterial- and immune-associated virulence factors contribute to CoNS pathogenicity. This study aimed to identify and describe bacteriological and immunological markers associated with colonising and infective CoNS from neonates with confirmed CoNS-sepsis at Tygerberg Hospital, Western Cape. Methods: Six neonates were recruited from September 2023 to May 2024. Based on the study’s exclusion criteria, two neonates were excluded from further analysis. Microbiological and biochemical testing was performed on CoNS isolated from skin and blood specimens of four neonates. CoNS were speciated using Matrix-Assisted Laser Desorption/Ionisation Time-of-Flight (MALDI-TOF). Antimicrobial susceptibility, bacterial growth and biofilm formation was used to assess phenotypic virulence. To assess genetic virulence determinants, short-read and long-read whole genome sequencing was performed to identify in silico multilocus sequence types (MLST), antimicrobial resistance genes, mobile genetic elements, and virulence-associated genes. Reverse-transcription real-time PCR was used to assess the relative expression levels of three virulence-associated genes (icaADB, aap/sesF, and sesI) of infective isolates relative to those expressed in the colonising CoNS. Resistance to granulocyte and monocyte phagocytosis was assessed in the colonising and infective isolates using a whole blood flow cytometric assay. Results: Staphylococcus epidermidis (9/18, 50%) and Staphylococcus haemolyticus (4/6, 67%) were the common CoNS isolated from skin and blood specimens. Ten CoNS (six colonising and four infective) were included in this study, and all isolates were multidrug resistant, but remained susceptible to linezolid and vancomycin. Non-susceptibility to penicillin G (100%) and rifampicin (3/4, 75%) was mostly observed in the infective isolates. S. haemolyticus was more non-susceptible (non-susceptibility to >7 antibiotics) than S. epidermidis (non-susceptibility to ≤7 antibiotics). Additionally, the colonising isolates were weak biofilm-formers (OD595 = 0.209 ± 0.27), while the infective isolates were characterised as non-biofilm formers (OD595 = 0.179 ± 0.16). The resistome, mobilome, and virulome of the colonising and infective isolates were comparable, with more virulence-associated genes present in S. epidermidis genomes compared to S. haemolyticus. A three-fold and two-fold increase in the respective icaADB and aap expression was seen in infective isolates compared to the colonising isolates. Furthermore, infective CoNS isolates displayed more resistance to granulocyte phagocytosis (48.72 ± 9.27% of cells phagocytosed CoNS) and monocyte phagocytosis (50.65 ± 8.22%) compared to the colonising isolates with 62.79 ± 5.53% and 57.85 ± 4.54% phagocytosis, respectively. Conclusion: The significant differences of virulence markers detected in the colonising and infective CoNS isolates could not be deduced due to the small sample size. However, similar bacteriological virulence phenotypes and genotypes were observed, highlighting either similar pathogenic levels in the colonising and infective CoNS, or the presence of pathogenic CoNS circulating TBH that colonised neonates therein. The use of biofilm-associated gene expression (icaADB and aap genes) and resistance to phagocytosis could aid in the discrimination of significant CoNS isolation from contaminants. Lastly, S. epidermidis and S. haemolyticus isolates displayed different phenotypic and genotypic virulence profiles, suggesting the separate species investigation in future. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2025-06-06T09:13:32Z 2025-06-06T09:13:32Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132415 Stellenbosch University xv, 138 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Biochemical markers Neonatal infections -- Immunological aspects Staphylococcal infections Septicemia in children UCTD Hendricks, Tharwat Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape |
| title | Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape |
| title_full | Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape |
| title_fullStr | Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape |
| title_full_unstemmed | Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape |
| title_short | Assessment of bacteriological and immunological markers associated with coagulase-negative staphylococci (CoNS) in neonates at Tygerberg Hospital, Western Cape |
| title_sort | assessment of bacteriological and immunological markers associated with coagulase negative staphylococci cons in neonates at tygerberg hospital western cape |
| topic | Biochemical markers Neonatal infections -- Immunological aspects Staphylococcal infections Septicemia in children UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132415 |
| work_keys_str_mv | AT hendrickstharwat assessmentofbacteriologicalandimmunologicalmarkersassociatedwithcoagulasenegativestaphylococciconsinneonatesattygerberghospitalwesterncape |