Date of Publication
11-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Biology
Subject Categories
Microbiology
College
College of Science
Department/Unit
Biology
Thesis Advisor
Esperanza C. Cabrera
Defense Panel Chair
Michael B. Ples
Defense Panel Member
Glenn G. Oyong
Mariquit M. De Los Reyes
Sharon M. Villanueva
Leslie M. Dalmacio
Abstract (English)
Antimicrobial resistance in Neisseria gonorrhoeae continues to compromise effective treatment worldwide. This study characterized N. gonorrhoeae isolates from female sex workers undergoing routine health clearance, focusing on antimicrobial susceptibility, resistance-associated mutations, and selected virulence genes. From 100 cervical swabs, 25 isolates were confirmed as N. gonorrhoeae using phenotypic methods and 16S rRNA gene sequencing. Antimicrobial susceptibility testing by disc diffusion revealed 100% resistance to ceftriaxone, cefixime, azithromycin, and spectinomycin, with additional resistance to ciprofloxacin (96%), penicillin (96%), and tetracycline (88%). MIC testing confirmed complete resistance to cefixime and high resistance to ceftriaxone (96%) and azithromycin (96%). For ciprofloxacin, 60% of isolates were resistant, 36% intermediate, and 4% susceptible. Penicillin MIC results showed 28% resistance and 72% intermediate susceptibility, with no fully susceptible isolates. Tetracycline MICs demonstrated 48% resistance, 28% intermediate susceptibility, and 24% susceptibility. All isolates exhibited drug resistance, with 8% classified as multidrug-resistant and 92% as extensively drug-resistant. Molecular analysis identified mosaic penA mutations (I312A, V316M, G545S), mtrR substitutions (G45D, H86Y), gyrA D95G mutations, and porB1b alterations (G120L, A121R, A121D). No mutations were detected in the 23S rRNA gene despite phenotypic azithromycin resistance, suggesting alternative resistance mechanisms. Molecular docking supported the functional impact of these mutations on antibiotic binding. Virulence gene analysis demonstrated universal amplification of pilE (100%), absence of opa amplification (0%), and limited amplification of rfaK (24%) and lgt (28%) genes. These findings demonstrate extensive resistance and complex molecular mechanisms among asymptomatic carriers and highlight the need for strengthened molecular surveillance and updated treatment strategies.
Abstract Format
html
Abstract (Filipino)
Patuloy na kinokompromiso ng antimicrobial resistance sa Neisseria gonorrhoeae ang mabisang gamutan sa buong mundo. Sinuri sa pag-aaral na ito ang mga isolate ng N. gonorrhoeae mula sa mga babaeng sex worker na sumasailalim sa regular na health clearance. Nakatuon ang pag-aaral sa antimicrobial susceptibility, mga mutasyon na may kaugnayan sa resistensya, at mga piling virulence gene. Mula sa 100 cervical swab, 25 isolate ang nakumpirmang N. gonorrhoeae gamit ang mga pamamaraang phenotypic at 16S rRNA gene sequencing. Ipinakita ng antimicrobial susceptibility testing gamit ang disc diffusion ang 100% resistensya sa ceftriaxone, cefixime, azithromycin, at spectinomycin. Naitala rin ang karagdagang resistensya sa ciprofloxacin (96%), penicillin (96%), at tetracycline (88%). Kinumpirma ng MIC testing ang ganap na resistensya sa cefixime at mataas na antas ng resistensya sa ceftriaxone (96%) at azithromycin (96%). Para sa ciprofloxacin, 60% ng mga isolate ay resistant, 36% ay intermediate, at 4% ang susceptible. Ang mga resulta ng penicillin MIC ay nagpakita ng 28% resistensya at 72% intermediate susceptibility, kung saan walang isolate ang ganap na susceptible. Sa tetracycline MICs, naitala ang 48% resistensya, 28% intermediate susceptibility, at 24% susceptible. Lahat ng isolate ay nagpamalas ng drug resistance; 8% dito ay itinuring na multidrug-resistant at 92% ay extensively drug-resistant. Natukoy sa pagsusuring molekular ang mga mosaic penA mutation (I312A, V316M, G545S), mtrR substitution (G45D, H86Y), gyrA D95G mutation, at mga pagbabago sa porB1b (G120L, A121R, A121D). Walang mutasyon na nakita sa 23S rRNA gene sa kabila ng phenotypic azithromycin resistance. Ipinahihiwatig nito ang pagkakaroon ng mga alternatibong mekanismo ng resistensya. Sinuportahan ng molecular docking ang epektong gampanin o functional impact ng mga mutasyon na ito sa antibiotic binding. Ipinakita ng pagsusuri sa virulence gene ang universal amplification ng pilE (100%), kawalan ng opa amplification (0%), at limitadong amplification ng mga gene na rfaK (24%) at lgt (28%). Ang mga natuklasang ito ay nagpapakita ng malawakang resistensya at mga komplikadong mekanismong molekular sa mga asymptomatic carrier. Binibigyang-diin nito ang pangangailangan para sa pinaigting na molecular surveillance at mga napapanahong estratehiya sa gamutan.
Abstract Format
html
Language
English
Format
Electronic
Keywords
Neisseria gonorrhoeae; Gonorrhea--Philippines; Sex workers--Philippines
Recommended Citation
Tan, A. T. (2025). Characterization of Neisseria gonorrhoeae from female sex workers procuring work-related health clearances from the Social Hygiene Clinic of the Manila Health Department for antimicrobial resistance and virulence. Retrieved from https://animorepository.dlsu.edu.ph/etdd_bio/10
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Embargo Period
1-18-2027
