ABSTRACT
Due to increase in road traffic accidents resulting in compound fractures and also increase in the number of orthopaedic surgeons using implants, iatrogenic and chronic osteomyelitis is being encountered more frequently. The objective of this study was to describe clinical and microbiological characteristics of acute and chronic osteomyelitis with regard to virulence markers and antibiogram of isolates to prevent unnecessary morbidity and mortality.METHODSA total of 148 samples like pus or exudates or pieces of necrotic tissues were collected during surgery, if possible, otherwise aspirated. All samples were subjected to Gram staining and culture. Various organisms were identified by standard methods. Various virulence determinants were detected by phenotypic tests. Kirby-Bauer method was employed to perform the antimicrobial susceptibility on Mueller-Hinton agar [MHA]. For detection of methicillin-resistant Staphylococcus aureus (MRSA), MHA supplemented with 4% NaCl was used.RESULTSOut of the 148 cases studied, 110 (74.3%) were male and 38 (25.6%) were female. The predominant number of osteomyelitis cases was found in the age group of 26-30 years, of these 48.5% (16/33) occurred following orthopaedic implants and 24.2% (8/33) due to post-operative wound infections. Staphylococcus aureus was the main isolate [43.9% (58/132)]. Escherichia coli [44.4% (4/9)] was the predominant isolate in the age group 36-40 years. The only isolate in the age group 46-50 years was Pseudomonas aeruginosa [100% (2/2)]. Almost all the bones were involved in all age groups, but spine was mainly infected in the 46-50 years age group. Differences in the presence of clumping factor, DNase, phosphatase, lipase, gelatinase, and presence of haemolysis on blood agar in MRSA were statistically insignificant (p= 0.13, 0.27, 0.95, 0.22, 0.40, 0.92 respectively) as compared to MSSA strains.CONCLUSIONSMRSA strains expressing some virulence factors with multi drug resistance might play a role in pathogenesis of osteomyelitis. Therefore, novel therapeutics targeting these virulence markers, instead of conventional antibiotic therapy, as well as following new guidelines, should take place in the future that might aid in the prevention and control of MRSA infections in our hospitals
ABSTRACT
Background: The aim of this study was to find out the clinical correlation between the presence of vancomycin‑resistant genes (van A and van B) and their expression as detected by phenotypic tests in colonized patients and in clinical isolates. Materials and Methods: Enterococci were isolated from various clinical samples and also from fecal specimens of colonized patients at the time of admission, after 48 h and after 5 days of admission. Identification to species level was done using standard methods. Vancomycin susceptibility in Enterococci was detected by disc diffusion test. Minimum inhibitory concentration was determined by agar dilution method. Multiplex polymerase chain reaction (PCR) was used to detect the presence of van genes. Results: Out of all the clinical and fecal samples processed, 12.0% isolates were either vancomycin resistant or vancomycin intermediate. Further, these isolates carried van A or van B genes as confirmed by PCR methods. Expression of van A gene was found to be more in Enterococcus faecalis (28.3%) as compared to Enterococcus faecium (25.0%) in both clinical and fecal isolates. 16.6% strains of E. faecium and 15.0% strains each of E. faecalis and Enterococcus gallinarum were found to carry van B genes. The overall prevalence of vancomycin resistant Enterococci (VRE) in colonized patients was about 9.6%. Prior administration of antibiotics had significant effect (P = 0.001) on VRE carriage. Urinary tract infection was the most common infection caused by vancomycin susceptible Enterococci (VSE), 105/214 (49.0%) and VRE, 13/36 (36.1%). There was no significant difference (P = 0.112) in the distribution of VRE and VSE in different infection types. Both clinical and fecal VRE showed maximum resistance to penicillin, ampicillin, and piperacillin. Resistance to linezolid was 2.8% in clinically isolated VRE. Conclusion: VRE in our study were found to be resistant to a number of commonly used antibiotics. The frequency of isolation of vancomycin resistant E. faecalis (VRE.fs), which is highly virulent, and the number of strains harboring van A gene in our hospital setup is high and needs to be addressed.