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Assessment of Polyhexamethylene Biguanide Hydrochloride-Resistance in Purpureocillium Species and Development
Takako Yamamoto1, Kouichi Hosoya2, Sayaka Ban3
1R&D, Safety Science Research, Kao Corporation.
Abstract:
Purpureocillium lilacinum is an opportunistic pathogenic fungus associated with endophthalmitis and keratitis. Previously, we isolated the strain P. lilacinum IFM 63780, notable for its high resistance to polyhexamethylene biguanide hydrochloride (PHMB), a common disinfectant and antiseptic used in dermatology and ophthalmology. In this study, we assessed the drug resistance profiles within the genus Purpureocillium. The minimum inhibitory concentration of PHMB for P. lilacinum and Purpureocillium takamizusanense was significantly higher compared to other species, while susceptibilities to other antibiotics and antifungal agents were consistent across all species. We developed species-specific primers for identifying P. lilacinum (PlF/R) and P. takamizusanense (PtF/R) by targeting the β-tubulin gene. These primers effectively amplified species-specific sequences, even when used in mixed primer pairs for the multiplex PCR, and did not cross-react with other species. This rapid and straightforward method provides a highly specific and reliable approach for detecting P. lilacinum and P. takamizusanense.
Insights
Purpureocillium lilacinum and P. takamizusanense exhibit high resistance to polyhexamethylene biguanide hydrochloride (PHMB). New species-specific primers offer a reliable method for identifying these fungi, crucial for clinical diagnostics.
Area of Science:
- Medical Mycology
- Antimicrobial Resistance
- Molecular Diagnostics
Background:
- Purpureocillium lilacinum is an opportunistic pathogen causing eye infections like endophthalmitis and keratitis.
- A previously isolated strain, P. lilacinum IFM 63780, showed significant resistance to polyhexamethylene biguanide hydrochloride (PHMB), a common disinfectant.
- PHMB is widely used in dermatology and ophthalmology, making resistance a clinical concern.
Purpose of the Study:
- To investigate the drug resistance profiles of the genus Purpureocillium, focusing on PHMB.
- To develop a rapid and specific molecular method for identifying P. lilacinum and P. takamizusanense.
Main Methods:
- Determined the minimum inhibitory concentration (MIC) of PHMB for various Purpureocillium species.
- Designed and validated species-specific primers (PlF/R and PtF/R) targeting the β-tubulin gene.
- Employed multiplex PCR to assess primer specificity and cross-reactivity with other fungal species.
Main Results:
- P. lilacinum and P. takamizusanense displayed significantly higher PHMB MICs compared to other species within the genus.
- Susceptibility patterns to other antibiotics and antifungals were consistent across all tested Purpureocillium species.
- The developed primers specifically amplified target sequences, enabling accurate identification in single and multiplex PCR assays without cross-reactivity.
Conclusions:
- Certain Purpureocillium species possess inherent resistance to PHMB, necessitating careful disinfectant selection in clinical settings.
- The novel species-specific primers provide a highly sensitive, specific, and reliable tool for the rapid molecular identification of P. lilacinum and P. takamizusanense.
- This diagnostic advancement aids in the accurate detection and management of infections caused by these opportunistic fungi.
