Microbiological parameters in patients with inflammatory complications after knee and hip joints endoprosthesis replacement and their diagnostic evaluation

Abstract

Introduction. Presently in the inflammatory joint diseases diagnosis and treatment microbiological examination plays a leading role. This is due to the infectious diseases frequency general increase, the hospital infections incidence rise risk, the widespread use of antimicrobial agents in medical practice and the change in the infectious foci microbiocenosises structure. Microbiological and, if necessary, serological studies of articular fluid are fundamental components of diagnosis and inflammatory joint diseases effective treatment selection. Etiological agents of inflammatory processes in joints can be microorganisms of different groups. According to the literature, up to 80% of bacterial arthritis cases cause gram-positive cocci, among which S.aureus predominates. At the same time, the number of methicillin-resistant strains of this pathogen (MRSA) increases annually. Less commonly, from the affected joints β-hemolytic streptococcus group A and other groups streptococcus, gram-negative rods, microscopic fungi and anaerobic bacteria are isolated. In view of the microorganisms biological nature characteristic, microbiological studies do not always make it possible to isolate the causative agent of infection. A major problem in bacteriological diagnostics is the periprosthetic and hematogenic infections low-grade causative microorganism, as well as subacute and chronic processes course presence. These include coagulase-negative staphylococcus (for example, Staphylococcus epidermidis) and anaerobic bacteria. Diagnostic and therapeutic difficulties can also be due to the pathogens ability to form antimicrobial therapy resistant microbial biofilms. It is reported that an antibacterial drugs uncontrolled intake, the biofilms formation, errors in the collection and transportation of biological material, can cause a situation when the joint infection infectious agent can not be detected in approximately (10-20) % of the cases.Materials and methods. The material for the studies, were synovial fluid samples collected from 64 patients of the SE "Sytenko Institute of Spine and Joint Pathology, NAMS Ukraine" clinic. The patients’diagnosis were status after knee and hip joints endoprosthesis replacement with inflammatory complications. The biological material was tested in the 2015-2017 period. The synovial material collection was conducted by the attending physician by the joint puncture method. The articular fluid withdrawn into the syringe was immediately got to a microbiological laboratory. The biological samples inoculation was carried out into a fluid thioglycollate storage medium, then to obtain the aerobic and facultative-anaerobic microorganisms pure cultures the isolate passage were conducted to Columbia blood agar, salt agar and Endo medium. Further isolated microorganisms identification was performed by standard methods in accordance with current guidelines. The microorganisms cultures were observed for 14 days. In the absence of microflora’s growth, a preliminary negative result for all synovial material was given after 5-7 days. If there was a based on the disease anamnesis and clinic suspicion on the slowly growing pathogens presence the timing of the studies was increased.The isolates sensitivity to antimicrobial agents was determined by the disc-diffusion method.In determining the microorganism’s sensitivity 29 antibacterial drugs from 8 chemical groups were used: β-lactams, fluoroquinolones, macrolides, aminoglycosides, tetracyclines, lincosamides, glycopeptides, oxazolidinones, glycylcyclines. Results and discussion. As a result of the microorganisms’ identification, 68 cultures of facultative-anaerobic bacteria and microscopic fungi were isolated from the joint fluid. 82.3% of bacterial isolates were obtained in monoculture (n = 56). Of these, 25.0% of the cultures (n = 14) were staphylococcus specieswith ability to coagulate the blood plasma (S. aureus (n = 9), S. intermedius (n = 5)), other staphylococcus isolation rate was 60.7% (S. epidermidis ( n = 21), S. haemolyticus (n = 9), S. simulans (n = 4)). Pathogenic streptococcus species was isolated from 5.4% of the samples (S. pyogenes (n = 3)). K. pneumonia cultures were isolated from 8.9% of biological material samples (n = 5). Mixed microcenosises were detected in 6 samples of the biomaterial. The cultures associations consisted of two microorganisms specieswith the associations S. intermedius - S. pyogenes, C. lusitania and C. neoformans (n = 4) prevailing. Two other microbiocenoses were represented by Candida with S. pyogenes and S. haemolyticus. The bacterial cultures sensitivity to antimicrobial agents analysis showed that allS. aureus isolates were sensitive to linezolid, levofloxacin and theceftriaxone-sulbactamcombination. Generally it was determined that the most effective drugs for gram-positive cocci are linezolid, to which 88.1% of the studied isolates are sensitive, including all S. aureus and S. haemolyticus cultures, and tigecycline, which has activity against 78.0% of gram-positive cocci isolates. The estimated aminoglycosides efficacy is 73.7%. The fluoroquinolones, carbapenems and the third generation cephalosporins with sulbactam combinations antimicrobial activity is manifested for 50% of all isolates obtained. About 30% of cultures were sensitive to lincomycin and the third generation cephalosporins - ceftriaxone, cefixime and cefoperazone.

Conclusions. 1. Microflora isolated from synovial fluid in case of the knee and hip joints is inflammatory diseases is represented by gram-positive cocci (86.8%) in most cases, gram-negative rods amount is 7.3% and fungi of Candida and Cryptococcus genera are made 5.9%. 2. The isolated microorganisms speciesantimicrobials sensitivity is characterized by individual diversity with a tendency to vancomycin resistance increasing in 44.4% of coagulase-positive staphylococcus isolates, of which 28.6% are S. aureus strains; 28.5% o are other staphylococcus speciescultures and 16.7% are S. pyogenes isolates. This indicates the exactly appropriate antibiotic therapy conducting necessity. 3. When choosing antibiotic therapy in patients in case of coxarthrosis and gonarthrosis it is recommended to take into account the bacterial isolates antibiotic resistance formation actual trends.