Objective. Explore colonization by opportunistic microorganisms organism of patients with rheumatoid arthritis (RA) during therapy with totsilizumab.

Materials and Methods. The study included 89 patients with RA (are women, mean age 57,50 ± 8,11 years and the duration of the disease 10,16 ± 7,05 years). Diagnosis of rheumatoid arthritis according to the established criteria of the American Rheumatism Association (1987). To 19 patients 6 totsilizumab infusions are carried out at a dose of 8 mg / kg during therapy with non-steroidal anti-inflammatory drugs. Comparison group consisted of 70 patients with RA without use of genetically engineered drugs in treatment. Study of the intestinal microflora, upper respiratory and urinary excretory tract conducted by bacteriological method with the release of a pure culture of conditionally pathogenic microorganisms and their identification.

Results. The quantitative and qualitative change in the resident and transient microflora was noted  in patients with RA during therapy with totsilizumab. Colonization of coagulase-negative staphylococci type S. aureus increased significantly. Frequency of detection of S. aureus in the large intestine, in the mucous membranes of the nose and in the urine increased (respectively, to 47.4%, 57.9% and 42.1%). The isolation frequency of S. aureus of these habitats in RA patients in the traditional treatment was 28.6%, 17.1% and 6.1%. totsilizumab application accompanied by a significant increase of the frequency of detection of opportunistic bacteria Enterobacteriaceae (p<0.01). Opportunistic pathogens Enterobacteriaceae were found in the intestines of 100% of patients in the application of totsilizumab  and in 25.7% of patients of the comparison group. The species composition of bacteria of the family Enterobacteriaceae species characterized by the release of Klebsiella, Enterobacter, Morganella and Proteus. The frequency allocation E. coli with changed enzymatic properties increased during therapy with totsilizumab. At 100% of the patients were allocated E. coli with low fermentative activity. In patients of comparison group these microorganisms were isolated in 58% of cases. But E. coli with reduced enzyme activity were detected in the colon of patients using the totsilizumab in smaller quantity - 4,40 ± 1,40 log 10 CFU / g,  at concentrations in the faeces of patients in the comparison group titer 7,76 ± 0,46 log 10 CFU / g.  The application of totsilizumab in RA patients was accompanied by increasing of the level of microorganisms with hemolitic  activity to  5,11 ± 0,93 log 10 CFU / g,  in the control group these figures were respectively  3,89 ± 0.86 log 10 CFU / g.  S.aureus and opportunistic bacteria of the family Enterobacteriaceae colonization of the patient's organism using totsilizumab may increase the risk of purulent infections in patients with RA. Opportunistic bacteria can stimulate the synthesis of  cytokines by activated cells of mucous intestines. Studying of features of microflora in patients with RA using totsilizumab allows to reveal the possible risk factors for infectious complications.

Conclusion. Application totsilizumab is accompanied by colonization of opportunistic pathogens in patients organism. Significantly increased frequency of  S. aureus isolation and bacteria of the family Enterobacteriaceae, that may be one of the factors of increased risk of infectious complications.