Survival of different microbial strains in pure and diluted tattoo inks

Several microorganisms can be found in tattoo inks injected into the skin, despite the ink matrix being considered inhospitable to microbial growth. Studies on the microbial quality of tattoo inks have reported the presence of microorganisms in most of the samples. This study aimed to assess the survival of environmental and human microbial species, selected on the specific criteria, in tattoo inks. Undiluted sterile black ink and serial dilutions (10-fold/100-fold) were each separately seeded with four bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus pumilus, Mycobacterium fortuitum), one yeast (Candida albicans), and one mould (Fusarium solani). Their survival was periodically tested using cultural methods. No tested microorganisms were able to survive in undiluted ink, except for B. pumilus that survived up to 3 weeks. All the tested species, except for S. aureus, showed survivability for up to 10 weeks in 100-fold diluted inks, and P. aeruginosa, M. fortuitum, and C. albicans were even able to grow. B. pumilus and F. solani had good rates of survival even at the smallest dilution. The ability of microorganisms to survive and grow in tattoo inks could have health implications if contaminated ink dilutions are used during tattooing practices and stored for a long time.