An assessment of chiropractic adjustment beds as reservoirs for normal flora and infectious bacterial pathogens at a chiropractic teaching clinic

Background: Research has indicated the majority of bacteria on chiropractic adjustment beds (beds), can persist on dry inanimate surfaces for months. Thus, insufficient disinfection procedures create continuous sources of pathogens endangering patients and healthcare workers alike. This research study aimed to assess the beds as reservoirs for micro-organisms, at a chiropractic teaching clinic (clinic) in South Africa. Method: A selection of samples obtained from the headrests and armrests of the beds were serially diluted, plated in duplicate (using the spread plate technique) and incubated for 24-48 hours at 37°C. After inspection for the presence of micro-organisms, those present were enumerated to determine their quantities, the microbial build-up throughout the day, as well as the degree of the transmission from the patients to the beds during treatment. The incidence of the micro-organisms was established, along with their identities, using microscopic and macroscopic characteristics. These micro-organisms were also used to assess the efficacy of the disinfectant currently in use by the clinic. Results: Microbial growth was present on 89.4% of the beds sampled. The quantities of the micro-organisms increased significantly (p=0,027) from 7:30 am to 16:30 pm, with the median increasing from 25 colony forming units (cfu) / cm2 to 714 792 cfu/ cm2. The microbial build-up was highly significant (p<0.001), with a median of 346 cfu/ cm2 at 7:30 am and 10:30 am; increasing to 162 291 cfu/ cm2 by 13:30 pm and 250 million cfu/ cm2 by 16:30 pm. There was also a significant increase (p<0.001) in the quantity of micro-organisms during treatment with a median of 0 cfu/ cm2 before treatment that rose to 23 479 cfu/cm2 after treatment, indicating that the micro-organisms present on the beds were being deposited by the patient`s skin during the treatment. The most prevalent micro-organisms identified were Staphylococci and Serratia, with an average of 59% and 40% of colonies; while Micrococci and Bacilli were relatively uncommon. No growth was evident after 5 minutes of exposure to the disinfectant during the growth inhibition test. For the Kirby Bauer test, the average size of the zone of inhibition increased as the dilution decreased. The disinfectant is effective but more so against the Gram-positive than the Gram-negative bacteria. The disinfectant was 5,0, 5,5 and 5,6 times more effective than phenol in eradicating Staphylococci, Serratia and Bacilli, respectively. Conclusions and Recommendations: This study showed that micro-organisms were present on the beds. Staphylococci and Serratia have been implicated in many healthcare associated infections. The present disinfectant is effective, but should be used in between every patient. A different or additional disinfectant that is more effective against the Gram-negative bacteria should be considered for future use.