If you search for P Hemarajata online, you may come across Peera Hemarajata, M.D., Ph.D., D(ABMM), Assistant Director of the Public Health Laboratory at the Los Angeles (LA) County Department of Public Health instead. Although his Thai given name, พีร์, most closely translates to "P," Hemarajata was not allowed to use this translation as his first name on his passport or his U.S. visa application. At his father’s suggestion, he chose ‘Peera,’ derived from the same Sanskrit root, instead. This tension over Hemarajata’s name epitomizes his journey to both remain true to his Thai identity and assimilate to American culture. To his frustration, Americans sometimes insist on calling him Peera even when he asks to be called P, presumably because they are uncomfortable with the latter.

Hemarajata received his medical degree from Chulalongkorn University in Bangkok in 2006. He recalls being heavily involved in direct patient care by the time of his externship (similar to a medical internship in the U.S.), and rapidly realizing that he was too emotionally invested in his patients and it was beginning to affect his mental health. He began exploring career options and remembered how much he enjoyed his microbiology classes. To teach microbiology at the university level, however, he needed a Ph.D.

Hemarajata came to the U.S. in 2007 to attend graduate school at Baylor College of Medicine in Houston. “Of course, I had to deal with the casual racism on the streets, but generally I felt welcomed and accepted when I was at school,” he said of his time in Texas. “There were plenty of Asian students in my class and among the faculty as well,” he explained, a sentiment that underlines the pivotal role representation can play in inclusion. Hemarajata does remember someone rolling down their car window and yelling at him to go back to China—ironic and a lot of wasted effort considering he isn’t from China. Unfortunately, it would not be the last time he encountered this attitude.

In Dr. James Versalovic’s laboratory at Baylor, Hemarajata studied Lactobacillus reuteri, a bacterial member of the human gut microbiome and a popular species in probiotic formulations. L. reuteri tamps down inflammation in the gut by converting the amino acid L-histidine into histamine, which suppresses the production of proinflammatory cytokines, like tumor necrosis factor (TNF), by immune cells. Hemarajata worked out key details of this process, identifying Lactobacillus reuteri-specific immunoregulatory protein (RsiR) as a transciptional upregulator of the histidine decarboxylase enzyme, HdcA, and its helper protein, HdcB. He also developed a transposon mutagenesis system for L. reuteri and used it to show that disrupting the proton-chloride antiporter gene, eriC, significantly reduces histamine production. EriC helps relieve membrane potential accumulated during amino acid decarboxylation in Escherichia coli, and likely plays a similar role in L. reuteri. Understanding how L. reuteri regulates conversion of histidine to histamine can potentially lead to insight on how to stimulate this anti-inflammatory property and even how to genetically engineer better probiotic strains.

Although he felt welcome in graduate school, Hemarajata also felt tremendous pressure to fit in. A more senior student advised him to work on his English so that he would be taken seriously. “As an immigrant, I… feel I have to work harder and accomplish more in order to prove my worth. This [didn’t] really go away even after I became naturalized,” he said of acclimating to his second country. He jokes that he is losing his fluency in Thai and acknowledged that “I may have permanently lost parts of my identity as a Thai person in an attempt to build an entirely new persona.” In grad school, Hemarajata recalls curiosity from colleagues about his culture and feels sure one friend in particular likely still remembers the date of the Songkran Festival (Buddhist New Year) all these years later. He wishes that someone had pointed out at the beginning of his journey that the "values, culture and traits that formed my identity and made me different from everyone else could also make me a better scientist. … My willingness to put my best effort in everything I commit to, being gracious and humble and open to learning and criticism and treating everyone with respect—these qualities are the direct results of having been brought up in a traditional Asian household."

After Hemarajata received his Ph.D. in 2013, he went on to do a brief postdoc under Versalovic at the Texas Children’s Microbiome Center, using 16S amplicon sequencing to characterize the gut microbiome in kids with ulcerative colitis or Crohn's disease before and after fecal transplantation. However, he realized he had strayed too far from medicine. A friend told him about ASM's Subcommittee on Postgraduate Educational Programs (CPEP) fellowships, which provide training in clinical microbiology, and Hemarajata finally found his niche. In 2014, he began a CPEP-accredited Medical and Public Health Laboratory Microbiology Fellowship at the University of California, Los Angeles (UCLA) under the direction of lab director, Dr. Romney Humphries, and associate lab director and CPEP program director, Dr. Omai Garner.

Hemarajata's self-taught next generation sequencing and bioinformatics skills soon came in handy. UCLA’s clinical laboratory noticed an increase in carbapenem-resistant Enterobacteriaceae (CRE) infections, specifically involving Klebsiella pneumoniae carrying the bla_OXA-232 gene, among patients at Ronald Reagan UCLA Medical Center. By looking for procedures the patients had in common, the infection prevention team identified the likely source as 2 contaminated duodenoscopes (devices used to look at the small intestine). But it was Hemarajata and another CPEP fellow, Dr. Shaun Yang (currently UCLA's Assistant Medical Director of Clinical Microbiology), who confirmed the identity of the index patient and the chain of transmission using whole genome sequencing. The manufacturer eventually recalled the impossible-to-clean devices after additional outbreaks were linked to them.

With this taste of real-world disease tracking under his belt, Hemarajata decided to lengthen his CPEP rotation at the LA County Public Health Laboratory and sit for the California certification exam in public health microbiology. He’s been the Assistant Director of LA County’s public health lab under laboratory director Dr. Nicole Green (who is also an Asian American clinical and public health microbiologist), since 2018 and was instrumental in getting SARS-CoV-2 whole genome sequencing up and running in the lab. "We were the first local public health lab in California to be able to perform SARS-CoV-2 sequencing in-house from beginning to end, without outsourcing any part of the process," he said proudly. The lab was recently awarded more than $6.4 million from the American Rescue Plan to expand their whole genome sequencing capacity.

As a Thai person who looks East Asian (Thailand is considered Southeast Asia) during a pandemic that first came to light in China, Hemarajata said he thinks that anti-Asian sentiment has gotten worse and more frequent over the past year. Some of it has been directed at him personally, including echoes of the "go back to China" incident. Despite this atmosphere, Hemarajata said "the work I put into protecting the health and well-being of Americans is a great contribution that I am making to support the communities and country that welcomed me."