Sexually transmitted infections (STI) are common worldwide and those caused by bacteria, in particular, are increasing. The most common bacteria causing STIs are Chlamydia trachomatis, Neisseria gonorrhoea, Mycoplasma genitalium and Treponema pallidium. STIs have varying clinical presentations including urogenital, pharyngeal and rectal involvement, alongside asymptomatic infections, which contribute to the rapid spread of infections.
The urogenital chlamydial infection caused by C. trachomatis serotypes D–K affects young adults and is the most common bacterial STI. Over the last few years, there has been a rise in N. gonorrhoeae exhibiting high-level mono-resistance and multi-resistance to commonly used antibiotics. Increased antibiotic resistance has also been observed for M. genitalium, thus complicating treatment.
Nucleic acid amplification tests (NAAT) are used for rapid detection of pathogens responsible for causing STIs. Scientists from the Division of Bacteriology are working with the Division of Infectious Disease Diagnostics (IDD) to produce CE marked quality control diagnostic reagents for use in NAAT assays. These controls are designed to mimic a low positive clinical sample and to be used during the extraction and amplification phases of the assay. The reagents produced contain heat-inactivated non-infectious whole bacterial cells of C. trachomatis (CT), N. gonorrhoeae (NG), M. genitalium (MG) G. vaginalis, H. ducreyi and Ureaplasma urealyticum.
Antimicrobial resistance (AMR) in sexually transmitted infections (STIs) is a major public health concern, with Neisseria gonorrhoeae being designated as a “high priority antibiotic resistant pathogen” by the World Health Organization (WHO). Emergence of extensively drug resistant isolates globally have led to treatment failures and thus there is an urgent need for new antibiotics. Treatment failures mostly occur in pharyngeal gonococcal infection, recognised as a common route of transmission and the development of AMR. Treating pharyngeal infection and thus breaking the chain of gonococcal transmission is a key target area in the control efforts.
With no effective vaccine available, a new approach to treat and control of gonorrhoea should be considered. In collaboration with Allicin International Ltd, we are evaluating anti-gonorrhoeal activity of an aqueous extract of allicin from garlic. This compound has previously demonstrated antimicrobial properties against various bacteria, fungi, parasites and viruses. If allicin is found to be effective against gonococci in vitro, its use as a topical treatment (mouthwash) will be investigated for treating pharyngeal infection.
We recognise the challenges ahead with the continued need to tackle STIs, particularly with the growing incidence of antimicrobial resistance and the gap that exists in standardisation of diagnostic tests. We would welcome the opportunity to collaborate on STI research and vaccine development. We have a strong background in bacterial vaccines; particularly vaccine regulation and standardisation. We are uniquely placed at the interface of vaccine development and licensure and our research group has broad skills in microbial techniques, molecular microbiology, assays relevant to vaccine regulation and population genetics. If you are interested in collaborating or in the skills or services that we can provide, please contact us.
Dr Sunil Maharajan - Scientist Dr Rory Care – Senior Scientist