Monitoring of opportunistic and pathogenic microorganisms in surgical departments of Dniprodzerzhynsk

Abstract

The paper presents monitoring results of the spread of opportunistic and pathogenic microorganisms in patients of surgical departments of the Dniprodzerzhynsk city hospital No 7. 1464 strains of bacteria isolated from biological material of the patients from January to December 2012 were studied. Relevant standard methods of research and data interpretation in accordance with the regulatory guidelines were used. The microorganisms’ sensitivity to antibiotics was determined by the disk diffusion method. Assessment of the resistance of isolated microorganisms to antibiotics was made with the software Whonet 5.1. At the first stage of investigation sampling biological material and inoculation in the culture medium were made. The discharges of wounds, throat, nose, ears, vagina and urethra, and also urine from patients of surgical departments were sampled for bacteriological analysis. The main substratum was 5% blood agar. There may additionally be used the selective growth media (yolk-salt agar, Endo, and Saburo). At the second stage we identify microorganisms with bacterioscopic, bacteriological and biochemical methods. Identifying microorganisms of the genus Staphylococcus was made by the reaction of lecithinase presence, plasma-coagulation reaction and the mannitol oxidation reaction. For the identification of bacteria of the family Streptococcaceae the growth pattern in 0.5% sugar medium was used. It was differentiated from bacteria of the genus Enterococcus by plating onto egg yolk agar base and milk with 0.1% methylene blue. Identification of bacteria of the Enterobacteriaceae family was made by studying their colonies on dense differential diagnostic media. Suspicious colonies were transferred on a combined medium for primary identification (Olkenitsky's medium). Then the biochemical signs of enterobacteria were studied in the minimum number of tests. The third phase of the study included the determination of the sensitivity of microorganisms to antibiotics. To do that, we use the disc diffusion method. The antibiogram tests of isolated bacterial strains used Mueller-Hinton agar. According to the data obtained we assign of microorganisms to certain category of sensitivity: sensitive, moderately resistant or resistant. Monitoring of prevalent microorganisms showed that 61% (893 of 1464) isolates were gram-positive bacteria, 696 strains of them are staphylococci. 477 of these are identified as S. aureus, representing 68.5% of all Staphylococcus. We found coagulase negative staphylococci in 192 patients, and the strains of S. haemolyticus are dominated. Strains of the family Streptococcaceae isolated from 197 patients. Among them the E. faecalis accounted for 66% of the total number of Streptococcus. Gram negative bacteria were presented by the families Enterobacteriaceae and Pseudomonaceae. Enterobacteriaceae accounted for 90.7% (518 of 571). E. coli plays the leading role and accounted for 42% of all Enterobacteriaceae. The strains of P. aeruginosa were identified in 53 patients. S. haemolyticus has played an important role as a pathogen as well as S. aureus. Its resistance to antibiotics is much higher than that of S. aureus. Although S. haemolyticus is opportunistic coagulase negative, it can be isolated from patients not only with chronic, but with acute infection. Thus nowadays the strains of S. haemolyticus gained high pathogenic and virulent properties.