Molecular Surveillance Of Ceftazidime (CAZ) Resistance In Melioidosis

Iris Irby

Authors:  Iris F. Irby, Monhammad Siddiqur Rahman-Khan, Yukari Fukushima, Yuki Ouchi, Yasuhiko Suzuki, Chie Nakajima, Apichai Tuanyok

Faculty Mentor:  Apichai Tuanyok

College:  College of Veterinary Medicine


Melioidosis is caused by Burkholderia pseudomallei, a Gram-negative bacterium found in soil and water in tropical regions predominantly in Southeast Asia and northern Australia. Treating melioidosis is complicated because the pathogen is resistant to most antibiotics used in the initial empirical management of sepsis, including ceftazidime. Ceftazidime (CAZ) is the primary intravenous (IV) drug of choice recommended for treating melioidosis. CAZ is a third-generation cephalosporin antibiotic with bactericidal activity. The primary goal of this project was to identify genetic and molecular basis of CAZ resistance mechanisms in a large collection of B. pseudomallei collected from a longitudinal cohort study in Thailand. This study has demonstrated that mutations of penA, a class A β-lactamase gene, can potentially cause CAZ resistance. Based on the findings from patients with treatment failures in Thailand during 1987-2007, our study has suggested strong associations between the increased minimal inhibitory concentrations of CAZ and multiple amino acid substitution (AAS) mutations in PenA and the multiplication of penA, which is one of the most common mechanisms that B. pseudomallei uses to survive the antibiotic treatment. We are currently developing real-time PCR assays to detect these mutations in clinical settings. This project will not only empower clinicians with innovative tools to monitor drug susceptibility for B. pseudomallei in real-time, but also has a significant impact on alteration of treatment(s) for melioidosis.

Poster Pitch

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Valerie Prytkova
Valerie Prytkova (@guest_856)
1 year ago


A rockstar!! I love how you give background information and tell us why your research is important! Marvelous presentation! Thank you for sharing!


Iris Irby
Iris Irby (@guest_2044)
Reply to  Valerie Prytkova
1 year ago

Thank you so much Valerie!

Nirali Pathak
Nirali Pathak (@guest_1626)
1 year ago

Hey Iris! Great thorough explanation of your project!

Iris Irby
Iris Irby (@guest_2066)
Reply to  Nirali Pathak
1 year ago

Thank you Nirali!!

Bryn Tolchinsky
Bryn Tolchinsky (@guest_3434)
1 year ago

Great work Iris! Excited to see where this project will go in the coming months. Hope you are enjoying the challenge of this project and best of luck at EPI!

Iris Irby
Iris Irby (@guest_3584)
Reply to  Bryn Tolchinsky
1 year ago

Thank you so much Bryn! I love the project and EPI. Thank you for all of your help I don’t know where I would be without you and Aleeza!

Emily In
Emily In (@guest_4234)
1 year ago

Hi Iris! This was such an interesting presentation, and your poster looks amazing! Thank you for sharing!

Iris Irby
Iris Irby (@guest_5044)
Reply to  Emily In
1 year ago

Hi Emily! Thank you!

Zak Kostamo
Zak Kostamo (@guest_4850)
1 year ago

Wow Iris, you are doing incredible. I cannot wait to see where all of this leads you. Hope you are enjoying your time at the EPI. Love the poster.

Tatiana Delaleu
Tatiana Delaleu (@guest_5670)
1 year ago

Congratulations!!! I love your poster it looks beautiful.

Iris Irby
Iris Irby (@guest_6986)
Reply to  Tatiana Delaleu
1 year ago

Thank you Tatiana!

Lindsey Kuchenbecker
Lindsey Kuchenbecker (@guest_7756)
1 year ago

Amazing job on your poster and presentation!