Biotyping and genotyping of seven strains of Cutibacterium acnes

Abstract

Bacterial typing is the process of distinguishing between different strains, it is essential for epidemiology, identifying source of infection and guiding treatment. This study aimed to detect the biotypes and genotypes for seven strains of Cutibacterium acnes obtained from the University of Mosul, already isolated from individuals with acne vulgaris in Mosul city (Iraq) and diagnosed by the molecular method based on 16S rRNA gene. Accuracy in biotyping depended on which type of the sugar (ribose, erythritol and sorbitol) was consumed by C. acnes, each sugar was placed separately in culture media with 1% concentration in the presence of phenol red to detect sugar fermentation. The C. acnes isolates were cultured anaerobically for 3 days at 37 ºC. The results showed that four biotypes (I, III, IV and V) emerged in our isolates indicated by the change in color of the medium from orange to yellow depending on the fermentable sugar. The distribution percentage of bacteria among these biotype was dominated by the V biotype (42.8%), while the III biotype was percentage (28.6%) and the I and IV biotypes each took up a lesser percentage (14.3%). It is worth mentioning that the II biotype didn’t appear at all in any of the isolates. For genotype, it was based on genes (16s rRNA, ATPase, atpD, Toxin Fic family, recA, and soda), DNA was extracted and special primers were used, then they were amplified by PCR technique, after electrophoresis, the resulting bands showed that the seven isolates of C. acnes were distributed into two genotypes only. One of them is I A2 which the isolate CS6 belonged to, another genotype is a new one- it is worth noting that it is prevalent in six isolates out of seven, and contains (16s rRNA, ATPase, atpD, recA, and sodA) genes, and because it is a new genotype that was unique to our isolates in this study, we called it IV genotype. The conclusion of this study is that the biotyping and genotyping of C. acnes differed from other typing in another countries, therefore, caution should be exercised in using the appropriate treatment depending on the prevailing condition in the country and not adhering to what is known theoretically regarding the causes of infections.