Poster Presentation 25th International Pathogenic Neisseria Conference 2026

Global surveillance for different β-lactamase alleles reveals false-positive β-lactamase isolates with blaTEM-1 gene mutations (#080)

Vincent J. Oliver 1 2 , Gilda Bocco 1 2 , Nazia Rahman 3 4 , Anjali Sapre 5 , Melissa Martin 5 , Paul Rios 6 , Ann E. Jerse 1 , Adriana Le Van 1 2
  1. Uniformed Services University, Bethesda, MD, USA
  2. Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
  3. Cherokee Nation Strategic Programs, Tulsa, OK, USA
  4. Global Emerging Infections Surveillance Branch, Armed Forces Health Surveillance Division, Silver Spring, MD, USA
  5. Multidrug Resistant Organism Repository and Surveillance Network, Walter Reed Army Institute of Research , Silver Spring, MD, USA
  6. US Naval Medical Research Unit SOUTH, Lima, Peru

The Global Emerging Infectious Surveillance Program of the U.S. Department of War, Armed Forces Health Surveillance Branch, supports a repository and reference laboratory for Neisseria gonorrhoeae (GC) isolates recovered from routine care at several overseas (OCONUS) labs though collaborative surveillance projects. Here we report the use of phenotypic data in conjunction with molecular typing and whole genome sequencing (WGS) to describe trends in the production of β-lactamase (βL) in isolates collected from seven different geographical study sites: Thailand, Philippines, Peru, Georgia, Uganda, Kenya, and Ghana.

Isolates collected from patients between 2012 and 2026 were confirmed as GC (n= 1390) using standard biochemical and serological methods. Susceptibility to eight different antibiotics was determined by Etest. βL activity was determined by nitrocefin hydrolysis. 

Sixty-three percent of isolates out of 1,390 GC positive samples were βL positive (n=879) by the nitrocefin test. WGS analysis identified five different types of βL genes encoding TEM-1, TEM-135, TEM-239, TEM-122, or TEM-22. BlaTEM-1 was the most frequently detected bla allele in all study sites but differed in percentages between 15% (Georgia) and 76% (Philippines). BlaTEM-135 was identified in 4–23% of the isolates in Thailand, Philippines, Uganda, Kenya and Peru, while blaTEM-239 was only seen in Uganda (12%) and Kenya (8.7%). BlaTEM-122 and blaTEM-22 were identified in one isolate each from Thailand and Peru, respectively.

Thirty percent of isolates from Peru harboring the blaTEM-1 gene showed only reduced susceptibility to penicillin (PenRS), while the other 70% were resistant to penicillin (PenR). WGS analysis showed genetic relatedness based on single nucleotide polymorphism (SNP)-based analysis even though they had been collected from geographically separated clinics (Lima and Iquitos), and in different years (2014-2024). Sequence data also revealed a SNP (P12S) mutation in the blaTEM-1B gene for these PenRS isolates, which is in the signal-sequence-encoding region. 

These findings highlight the importance of continued global antimicrobial resistance surveillance and examination of both phenotypic and genomic susceptibility. Furthermore, WGS allowed us to discern false positive βL isolates by detecting a mutation in the blaTEM gene in PenRS isolates and showed the spread of this clone between two geographically separated clinics in Peru.