en Clinical microbiology Clinical microbiology پژوهشي Research <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Introduction</b>: Colorectal cancer (CRC) is a major global health issue. The gut microbiota has become an important factor in CRC development, with increased focus on microbes such as <i>Lactobacillus plantarum</i>. This study aimed to examine the presence and relative abundance (<i>GAPDH</i>-normalised copy number) of <i>L. plantarum</i> in colorectal tissues using a qPCR approach.</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Materials & Methods</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: </span></span></b>DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissues from three groups: tumour tissues from CRC patients (n = 50), matched adjacent normal tissues (n = 50), and normal tissues from individuals without CRC (n = 30). Species-specific primers targeting the <i>groEL</i> gene were used to measure <i>L. plantarum</i>, normalised against human <i>GAPDH</i>. Statistical analyses compared occurrence and levels across groups and assessed associations with age and sex.<span lang="FA" dir="RTL" style="font-family:"Times New Roman",serif"></span></span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Results</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: &nbsp;</span></span></b>Although bacterial load did not vary significantly across tumour, Adjacent, and Normal tissues, detection frequency was higher in tumour tissues (p = 0.0459). <i>L. plantarum</i> was also detected more often in individuals aged &ge;60 (p = 0.0024). Subgroup analysis revealed higher loads in Normal tissues of older adults and females and lower abundance in Adjacent tissues of females.</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Conclusion</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: &nbsp;</span></span></b><i>L. plantarum</i> was detected more frequently in tumour tissues despite consistent bacterial loads, indicating possible persistence rather than growth. These findings highlight age-, sex-, and tissue-specific colonisation patterns and emphasise the need for further research on the tumour-associated ecology of beneficial microbes.</span></span><br> &nbsp; Colorectal Neoplasm, Gastrointestinal Microbiome, Lactobacillus plantarum, Real-Time Polymerase Chain Reaction, Paraffin Embedding 12 23 http://jbrms.medilam.ac.ir/browse.php?a_code=A-10-747-3&slc_lang=en&sid=1 Farzaneh Korani farzanekorani@gmail.com 10031947532846008114 0009-0008-5782-3688 No Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran NayebAli Rezvani arezvani51@gmail.com 10031947532846008115 10031947532846008115 No Department of Clinical Biochemistry, Kermanshah University of Medical Sciences, Kermanshah, Iran Behrooz Sadeghi kalani Behroz.sadeghi@gmail.com 10031947532846008116 10031947532846008116 No Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran Reza Pakzad Rezapakzad2010@yahoo.com 10031947532846008117 10031947532846008117 No Department of Epidemiology, Faculty of Health, Ilam University of Medical Sciences, Ilam, Iran Parisa Asadollahi asadolahi.p@gmail.com 10031947532846008118 10031947532846008118 Yes Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran