Laboratory diagnosis of community-acquired bloodstream infection in therapeutic pathology.

Community-acquired bloodstream infections (CBSIs) occur in the out-of-hospital setting (44%) and increase the overall mortality from bloodstream infections (BSIs) by 7.2% per year. The development of CBSIs depends on both comorbid and polymorbid diseases and the patients' age. The causes of CBSIs are: respiratory, hepatobiliary gastrointestinal and urogenital tracts and dental interventions. The etiology of CBSIs is characterized by the isolation of coagulase-negative staphylococci (CNS) (32%), E. coli (27%). To investigate community-acquired bloodstream infection in therapeutic patients. The study included out-of-hospital patients (n=382). 4.5 ml of blood were taken intravenously into a closed vacuum system in order to obtain a buffy coat of blood, which was put on glasses for microscopy and Petri dishes with blood agar for cultivating under aerobic and anaerobic conditions. Microorganisms were identified by mass spectrometry. Microscopy of blood smears was used for rapid diagnosis of infection in the bloodstream. BSI was diagnosed in 183 (48.0%) out of 382 out-of-hospital patients. The etiology of CBSIs was studied on 297 isolated strains of microorganisms. CBSIs rather often complicated the underlying disease in women and young people. The spectrum of CBSI pathogens included aerobic and anaerobic bacteria and fungi. Gram-positive cocci with the leadership of S.epidermidis (25.7%) were more often isolated among bacteria. 70% of all isolated pathogens grew under anaerobic conditions. CBSIs were characterized by polymicrobiality (33.5%) of two to four different microorganisms in one blood culture; the species of associates of polymicrobial blood cultures are shown. Microscopic examination of blood smears revealed microorganisms in 97.1% of cases, including associations of bacteria with fungi (66.9%). CBSIs occurred after contour plastic, in diseases of the respiratory system, genitourinary system, oral cavity, skin and subcutaneous tissue. Microbiological examination of the buffy coat is an alternative microbiological method of CBSIs diagnosis, which includes microscopy and blood cultivating and has a high diagnostic efficiency (97.1% and 48% respectively). It can become an option for replacing imported blood culture automated systems.

[Possibilities of application of the liquid transport medium for capture of pathological material at laboratory diagnosis of a diphtheria infection.]

The main objective of laboratory diagnosis of a diphtheria is identification of the causative agent by means of the minimum quantity of diagnostic tests for obtaining the authentic answer in the most short time. One of the major stages is capture and delivery of pathological material on which the efficiency of carrying out and timeliness of issue of the final answer depends. Considering emergence in the market of commercial liquid transport mediums, assessment of their efficiency for diagnosis of diphtheria is advisable. In the real work the pilot studies allowing to predict efficiency of use of the commercial transport liquid medium ∑-Transwab® with the liquid medium of Ames in two systems - with the standard applicator (system 1) and with the thin extended tampon for sampling from narrow cavities - urethral and nazofarengialny are conducted (system 2). In a research used a control toxigenic strain of Corynebacterium diphtheriae of a biovar of gravis No. 665. In an experiment "imitated" operating conditions of the medical organizations for storage of tampons with pathological material on diphtheria before their transportation in laboratory - on a table at the room temperature (6 and 20 hours), in the refrigerator (6 and 20 hours), in the thermostat (6 and 20 hours). After an incubation all tampons sowed the environment for primary crops of pathological material on a blood tellurite agar.. Accounting of results was carried out in 24 and 48 hours of growth. It is established that the commercial transport liquid medium of Ames can be used for capture of pathological material on diphtheria in the second half of the working day at storage in the conditions of the refrigerator. At the same time, it is necessary to consider a tampon form as the best results on a identification of the causative agent of diphtheria have been received when using a universal tampon.

[Sensitivity of corynebacterium diphtheriae strains to antibacterial preparations].

AIM: Study the prevalence and mechanisms of resistance in circulating C. diphtheriae strains. MATERIALS AND METHODS: 664 C. diphtheriae strains isolated in 1987 - 2013 in various regions of Russia and sent to the reference center of Gabrichevsky Moscow Research Institute of Epidemiology and Microbiology were the object of the study. Antibiotic sensitivity of the strains was studied by disk-diffusion and E-test methods using 10 antimicrobial preparations. Nucleotide sequence analysis was carried out by using BLAST program and EMBL/GenBank database. RESULTS: Most of the studied strains turned out to be sensitive to all the antibacterial preparations used. 1.2% of C. diphtheriae strains turned out to be resistant to penicillin and 6.0% had intermediate level of resistance. 0.4 - 0.6% of the strains had intermediate level of resistance to macrolides, and 4.0 - 4.4% were resistant. 2.0% of the strains had multiple resistance. Erm(X)-specific PCR carried out in this study showed that all the C. diphtheriae strains resistant to macrolide antibiotics carry erm(X) gene. CONCLUSION: The results of the study indicate a fairly high level of prevalence for C. diphtheriae strains resistant to antibiotics.

[Multilocus sequencing of Corynebacterium diphtheriae strains isolated in Russia in 2002 - 2012].

AIM: Characterization of contemporary C. diphtheriae strains isolated in Russia by using multilocus DNA sequencing (MLST). MATERIALS AND METHODS: 28 toxigenic C. diphtheriae strains isolated in Russia in 2002-2012 and sent to diphtheria and pertussis reference center of Gabrichevsky Research Institute of Epidemiology and Microbiology were studied. C. diphtheriae strain genotyping was performed by using MLST based on atpA, dnaE, dnaK, fusA, leuA, odhA and rpoB gene fragments. Identification of alleles and ST was carried out according to EMBL/GenBank and PubMLST, eBurst approach was used for cluster analysis. RESULTS: By using MLST contemporary toxigenic C. diphtheriae strains isolated in Russia in 2002 - 2012 were characterized. 8 genotypes (ST41, ST5, ST8, ST28, ST25, ST44, ST-new1 and ST-new2) were identified, 3 among them were dominating--ST8, ST28 and ST-new1. Most of the toxigenic strains belong to biovar gravis and ST8. Among biovar mitis strains a higher heterogeneity by ST membership was noted, but with prevalence of ST28 strains. CONCLUSION: Use of MLST allowed to characterize contemporary circulating population of toxigenic C. diphtheriae strains isolated in Russia and showed perspective of application of this method for characterization of diphtheria causative agent population and detection of epidemically significant strains, as well as juxtaposing of them with genetic structure of foreign strains.