Approbation of russian test strips for antimicrobial susceptibility testing of microorganisms by gradient diffusion method (E-test).

The most reliable criterion for the microorganisms antibiotic susceptibility is the value of the minimum inhibitory concentration (MIC). The gradient diffusion method (epsilometric test, e-test), carried out using test strips impregnated with an antimicrobial agent, allows to obtain the quantitative value of MIC, bypassing the time-consuming steps of the traditional method of serial dilutions. We tested strips for the epsilometric test, developed at Saint-Petersburg Pasteur Institute. The quality control, carried by testing the reference strains of E. coli ATCC 25922 and S. aureus 29213, confirmed compliance of the manufacturer's declared antibiotic concentration ranges. The MIC values obtained in the study of the antibiotic susceptibility of 101 clinical isolates of microorganisms of the ESKAPE group, isolated from patients of various hospitals in St. Petersburg, were compared to 8 antimicrobial agents using tested test strips and the corresponding M.I.C. Evaluator of the Oxoid (UK). A high percentage of compliance of MIC values was demonstrated, as well as full compliance of susceptibility categories for all microorganism/antibiotic combinations. The resulting divergences in the MIC values did not exceed one step of a double serial dilution, which is permissible according to GOST R ISO 20776-1-2010. The study showed that the test strips developed at the Saint-Petersburg Pasteur Institute DNT are an acceptable alternative to import tests and, after the registration certificate will be completed, can be offered to determine the susceptibility of microorganisms to antimicrobial agents in bacteriological laboratories.

Antimicrobial resistance of Escherichia coli, isolated from children's intestinal microbiota.

Recent studies have shown that bacterial resistance existed long before antimicrobials were used in medicine, and not only pathogens are resistant to antibiotics. 511 strains of E. coli isolated from the intestinal microbiota of children aged 1 month to 17 years living in St. Petersburg were studied: the susceptibility to 15 antibiotics was determined by the disk diffusion method, as well as the susceptibility to 6 commercial bacteriophages produced by «Microgen¼ (Russia). The b-lactamase genes of molecular families TEM, SHV, OXA, and CTX-M were detected by multiplex PCR. 39,3% E. coli isolates were resistant to one or more antimicrobial classes. The proportion of multidrug resistant isolates (resistant to 3 or more classes) was 16,6%. Multidrug resistance to clinically significant antimicrobial classes (extended-spectrum cephalosporins (ESC) + fluoroquinolones + aminoglycosides) was detected in 0,8% isolates. Resistance to aminopenicillins was detected in 29,5%, ESC - 11,2%, fluoroquinolones - 13,3%, tetracycline - 20,0%, chloramphenicol - 9,8%, aminoglycosides - 2,5% isolates. b-lactam resistance was due to the beta-lactamase production: to ampicillin - the molecular family TEM (81,9%), ESC - the CTX-M molecular family (87,7%) CTX-M1 - (66%) and CTX-M9 groups (34%). 43,5% multidrug resistant E. coli isolates were susceptible to at least one of the six commercial bacteriophages produced by «Microgen¼. The study showed that the intestinal microbiota of children is an important reservoir of E. coli resistant (including multidrug resistance) to various classes of antibiotics, and bacteriophage therapy is an alternative method for eradication of antibiotic-resistant E. coli.

[Current trends in the development of resistance to clinically significant antibiotics in Salmonella (review of literature).]

Salmonella is one of the leading bacterial pathogens of acute diarrhea as well as foodborne outbreaks. Salmonellosis can occur as gastroenteritis with the development of complications and generalization of infection, also the extra intestinal diseases that require antibiotic therapy are often registered. Currently, the effectiveness of many antibiotics is reduced due to the development of resistance in Salmonella. National Salmonella surveillance systems monitor Salmonella resistance to «critically important for medicine¼ antibiotics (extended-spectrum cephalosporins and fluoroquinolones), as well as multidrug resistance. Quinoloneresistant Salmonella is considered as a high-priority resitant pathogen by the World Health Organization. The article describes the current situation on salmonellosis in the world. Foreign and Russian current data about the leading Salmonella serotypes in different regions of the world are presented. The prevalence of clinically significant resistance depending of the Salmonella serotypes in countries with state monitoring systems is shown. The authors described the leading molecular resistance mechanisms (chromosomal and plasmid mediated) and showed their prevalence in different Salmonella serotypes. The article gives the information about Salmonella successful international multidrug resistant clones with specific resistance phenotypes and genotypes. The authors describe the molecular methods for detection of resistance mechanisms, and show the necessity and significance of antimicrobial susceptibility monitoring in the epidemiological Salmonella surveillance.

[Antimicrobial resistance and clinical significant resistance mechanisms of Salmonella isolated in 2014-2018 in St.Petersburg, Russia.]

The article presents the results of antimicrobial resistance monitoring of Salmonella isolated from children and adults with diarrhea in St. Petersburg in 2014-2018. In 746 isolates of 42 serovars more than 90,0% belonged to three: S. enteritidis (79,6%), S. typhimurium (6,8%) and S. infantis (3,8%). The antimicrobial susceptibility testing (according the EUCAST) to 7 classes of antimicrobials revealed the resistance in 78,6% of Salmonella. Low-level quinolone resistance (MIC of ciprofloxacin 0,12-0,5 mg/l) was detected in 63,3% isolates (S. enteritidis -71,0%, S. typhimurium - 15,7%, S. infantis - 89,3%) and was due to five kinds of single nucleotide substitutions in gyrA: Asp87Tyr - 36,1% of studied isolates (only S. infantis); Ser83Phe - 22,2% (only S. enteritidis); Asp87Asn - 19,4% (S. enteritidis, S. typhimurium, S. hadar, S. newport); Ser83Tyr -11,1% (S. enteritidis and S. infantis) and Asp87Gly - 8,3% (only S. enteritidis). Only in one S. kentucky isolate with high-level fluoroquinolone resistance (MIC of ciprofloxacin > 8,0 mg/l) two substitutions (Ser83Phe and Asp87Asn) were detected. Two Salmonella isolates (S. typhimurium and S. corvallis) had plasmid-mediated quinolone resistance (qnrS). Extended-spectrum cephalosporin resistance was found in 6 Salmonella serovars (1,6%). The bla-genes were detected: of genetic group CTX-M1 - in 10 isolates (serovars S. typhimurium, S. enteritidis, S. abony, S. coeln and S. virchow), CTX-M2 - in 2 S. typhimurium isolates, CTX-M9 - in three S. enteritidis isolates. In one S. typhimurium CTX-M1 and CTX-M2 were detected. The gene of CMY-2 (molecular class C cephalosporinase) was revealed in two isolates (S. newport and S. enteritidis). Our study showed that Salmonella (the main bacterial pathogen of acute diarrhea in children and adults) isolated in Saint-Petersburg had antimicrobial resistance to drugs of choice for salmonellosis treatment.

[Methodical aspects of antimicrobial susceptibility testing of Salmonella (review of literature).]

Salmonella is one of the leading food-borne infection pathogen: annually in the Russian Federation about 50 thousand cases of salmonellosis are registered. Antimicrobial therapy is necessary in the case of severe infection in children under 6 years and persons over 50 years, in patients with severe accompanying disease, as well as in the case of generalization of the infection. Beta-lactam antibiotics, quinolones and azithromycin are included in the list of drugs recommended for antimicrobial therapy of salmonellosis, including typhoid fever. The effectiveness of therapy largely depends on the appropriate antimicrobial susceptibility testing: the choice of testing method, indicator antibiotics and result interpretation. Salmonella belong to the Enterobacteriacae family and are characterized by common mechanisms of resistance to quinolones and beta-lactams, but antimicrobial susceptibility testing of Salmonella to these groups of antibiotics has a number of features. The article presents current data on the susceptibility of Salmonella, including S. Typhi, to antibiotics and leading clinically significant resistance mechanisms. The methodical aspects of Salmonella antimicrobial susceptibility testing of the drugs used for the treatment of salmonellosis (quinolones, beta-lactams and azithromycin) are described in detail. Interpretation of Salmonella testing results according the modern international and Russian recommendations are presented. The authors propose the algorithms for Salmonella antimicrobial susceptibility testing of quinolones, cephalosporins and carbapenems, as well as criteria for result interpretation, allowing the detection of clinically significant mechanisms of resistance to beta-lactams (production of beta-lactamases of different molecular classes) and quinolones (chromosomal mutations and acquired resistance genes).

Hypotensive effect of retabolil correcting the concentration of aldosterone during stress exposures.

Male rats were exposed to single or repeated (19 days) cold treatment (4°C) and non-cold stress (60-min shaking on a laboratory shuttle device). Retabolil had a hypotensive effect, which was accompanied by the prevention of a stress-induced increase in the concentration of a hypertensive hormone aldosterone. Under conditions of repeated stress, these effects were realized via µ-opioid receptors. Our results suggest that retabolil can be used as a hypotensive and aldosterone-blocking agent, at least during stress exposure in animals (and probably in humans).

[Farmacological effect of retabolil on aldosterone level and arterial pressure in rats under the action of vibrations].

The experiments were performed on male rats, which were subjected to single and multiply repeated vibrations (low-frequency, horizontal, high-amplitude) analogous to the action of motor transport vibrations. It is established that the administration of retabolil produces a hypotensive effect and blocks the vibration-induced increase in the level of hypertensive hormone aldosterone. Under conditions of the multiply repeated action of vibrations, both effects were realized via micro-opioid receptors. In the case of a single action, these receptors were only involved in a hypotensive effect but not mediated in aldosterone suppression. Both these effects were absent in the control group of animals (not subjected to vibrations). Therefore, retabolil can be used as a hypotensive and aldosterone-blocking drug for vibration-induced hypertension in animals and, probably, in humans.

Effects of dehydroepiandrosterone sulfate on blood pressure and aldosterone level via µ-opioid receptors.

Dehydroepiandrosterone sulfate (30 mg/kg) produced a hypotensive effect by preventing stress-induced surge of hypertensive hormone aldosterone in rats after manifold repeated, but not single stress exposure. Both effects were realized via µ-opioid receptors. Thus, µ-opioid mechanism of blockage of aldosterone surge can underlay the hypotensive effects of dehydroepiandrosterone sulfate at least under conditions of manifold repeated exposures.

[The characteristics of biological properties of E. coli O104:H4--the causative agent of large-scale alimentary ictus in Germany may 2001].

The review presents the characteristics of E. coli O104:H4, the causative agent of large-scale alimentary ictus in Germany in spring time 2011. The antigenic characteristics and factors of E. coli pathogenicity are taken into account. The causative agent has a combination of pathogenic factors of two groups of diarrheigenic Escherichia: shigella similar toxin, specific for entero-hemorrhagic E. coli and adhesins of enteroaggregative E. coli.

[Formation by Actinomyces malachitospinus sp. nov. of a physiologically active substance that stimulates zygote formation in Mucorales]. / Obrazovanie Actinomyces malachitospinus sp. nov. fiziologicheski aktivnogo veshchestva, stimuliruiushchego formirovanie zigot u Mucorales

A new species Actinomyces malachitospinus sp. nov. is described. It has spiral catenulate spores with spines, a gray aerial mycelium, and a green colonial mycelium, and contains no soluble pigments (including melanoid pigments). The strain of Act. malachitospinus INMI 217 produces a physiologically active substance that stimulates the formation of zygotes in Phycomyces blakesleeanus.