Resistance of Escherichia coli from healthy donors and from food--an indicator of antimicrobial resistance level in the population.

Escherichia coli, being an important part of normal intestinal flora, is a frequent carrier of antimicrobial drug resistance markers and food is the most important vector of antimicrobial resistance genes between humans and animals. The aim of this study was to confirm the presence and frequency of resistance markers in Escherichia coli from intestinal flora and from food as an indicator of antimicrobial resistance level in the population. The experiment included 100 fecal Escherichia coli isolates from healthy donors, 50 isolated in 2007 and 50 in 2010, and 50 from food samples. The resistance markers were found in all groups of isolates. The resistance to ampicillin and cotrimoxazole was most commonly found. The finding of multi-drug-resistant strains and resistance to ciprofloxacin is important. The frequency of resistance markers was similar in food and feces. The results of this study show the need to introduce systematic monitoring of antimicrobial resistance of these bacteria.

[Sensitivity of bacteria to antimicrobial drugs and interpretation of results].

INTRODUCTION: The discovery of antimicrobial drugs was a turning point in the permanent conflict between the mankind and microorganisms. However, due to the wide use and misuse of antibiotics in therapy and prophylaxis of infections the mankind is threatened by an alarming rise in the resistance of bacteria to drugs. Will this phenomenon turn us back to the pre-antibiotic era? DISCUSSION: The increasing resistance of bacteria has become a global public health problem: bacteria are showing a remarkable capacity to develop different mechanisms and avoid drug effect. Mechanisms of resistance are numerous and various: production of beta-lactamases (Ambler class A): TEM-I, TEM-2 and SHV-1 and mutants of classical enzymes with extended spectrum (ESBL) (e.g. in Klebsiella spp.) which results in the resistance to the 3rd generation cephalosporines and new metallo-beta-lactamases among Pseudomonas and Acinetobacter (resistance to carbapenems). The alteration of the target enzymes (PBP) leads to the Staphylococci resistance to methicillin and the responsible gene is mecA gene). The alteration of DNA gyrase due to the mutations of gyrA, gyrB, parC genes (accumulation of multiple mutations) results in the development of resistance to fluoroquinolones); and the active efflux system - "pumping out" of the drug from the bacterial cell leads to the resistance of a wide spectrum of different antibiotics. In order to choose the most efficient drug for therapy, it is necessary to investigate susceptibility of bacteria to antimicrobial agents. For that purpose, a disc-diffusion method according to CLSl standard procedure is performed. For invasive strains it is often necessary to determine minimal inhibitory concentrations (MIC) of antimicrobials. The methods that are in use are agar-dilution methods, E-test and automated MIC determination by VITEK 2 system. CONCLUSION: By molecular-biological methods it is possible to identify the mechanisms of resistance and detect the specific genes behind it (mecA gene). The targeted therapy prevents compromising of antibiotics valuable in treatment of severe infections (carbapenems).

[Impact of vaginal and cervical colonisation/infection on preterm delivery].

BACKGROUND/AIM: Preterm delivery together with insufficient body weight and death cases in newborns is the main issue in obstetrics. About 40% of preterm delivery is caused by infections. The aim of this study was to investigate whether and which bacterial infections of genital tract can be associated with preterm delivery, and depending on when diagnosis was made. METHOD: The study involved 216 pregnant women. According to pregnancy outcome, two groups were formed. The study group involved 29 pregnant women who had preterm delivery out of which nine were examined in I trimester, eight in II trimester and 12 in III trimester. The control group involved 187 pregnant women out of which 47 were examined in I trimester, 73 in II trimester and 67 in III trimester. Bacteriological examination of vaginal and cervical swabs was done in all pregnant women. Infection was diagnosed by finding bacterial antigen in cervical swabs or positive cultures of vaginal and/or cervical swabs followed by the presence of the increased number of polymorphonuclears in direct microscopic preparation. RESULTS: The results showed that in III trimester of pregnancy vaginal bacterial infection was statistically more common (p = 0.021) in women who had preterm delivery (66.7%) in relation to women who delivered in term (29.9%). In this period of gestation the increased number of polymorphonuclears in DMP of vaginal swabs is more common in the women of the study group (75%) than in the women of the control group (43.3%). Preterm delivery was registered in 16.1% women whose microbiological analyses were done in I trimester, 9.9% women in whom microbiological analyses were done in II trimester and in 15.2% pregnant women microbiologically tested in III trimester. CONCLUSION: Based on the obtained results it could be concluded that bacterial infections of genital tract and period of gestation when infection is diagnosed have influence on reducing perinatal morbidity and mortality caused by preterm delivery.

[Mechanisms of bacterial resistance to antibiotics].

Development of bacterial resistance to antibiotics brought many problems among which the most important are infections caused by multiple resistant bacterial strains. Bacteria have amazing 'equipment' of biochemical and genetic mechanisms to ensure evolution and spread of antibacterial resistance genes. The results obtained from very important projects all around the world and in our country show that bacterial resistance to certain groups of antibiotics is very high (up to 100%), because of uncritical use of antibiotics out of these groups. Due to the development of resistant bacterial strains, we may soon run out of efficient antibiotics for some patients. Outcome of the race between science and pharmaceutical industry on one side, and bacterial adaptation trough acquisition of resistant genes on the other side, is very uncertain. Actions must be taken to slow down the evolution and spread of antibiotic resistance genes in which the major single factor is the proper use of antibiotics in human medicine, veterinary medicine and agriculture, respectively.

[Antimicrobial resistance of the bacteria isolated from blood cultures in 2007].

INTRODUCTION: Antimicrobial resistance become emerging global problem. Particularly dramatic increase in the number and type of bacteria resistant to numerous and structurally different antibiotics has taken place in the last two decades. MATERIALS AND METHODS: A total of 558 strains of different bacteria isolated from blood cultures during 2007 were tested to susceptibility to different antibiotics by disc diffusion method according to CLSI. All strains were isolated and identified in the laboratories of Microbiology Center at the Institute for Public Health in Novi Sad. A total of 7748 blood cultures were processed and microorganisms were isolated from 558 of them. Blood samples were taken from the patients hospitalized in the Institutes and Clinics of Novi Sad Clinical Center and Institute for Health Care of Children and Adolescents in Novi Sad RESULTS: The structure ofpathogens shows that the most frequent isolates are Gram-positive bacteria, above all coagulase- negative staphylococci with 285 isolates (51,1%) followed with Enterococcus spp (41 isolates - 6,8%). Percentage of resistance to Methicillin in staphylococci strains was 66,7%; all isolates was susceptible to Vancomycine. Enterococcus spp showed 13,2% resistance to Vancomycine. Among Gram-negative pathogens, we find that the most frequent is Klebsiella spp with 40 isolates (7,2%) and have high resistance to wide spectrum Cephalosporins - 82,5%. Acinetobacter spp participate with 41 isolates (7,3%) and 43,9% isolates are resistant to Imipenem Also, Pseudomonas aeruginosa (20 isolates) shows high resistance to Imipenem (40%) but lower resistance to wide spectrum Cephalosporines (27,8%). CONCLUSION: Having compared the resistance to antibiotics in 2002 and 2007 speak for the trend of growing antimicrobial resistance to the very antibiotics which are recommended as the empiric or initial therapy-wide spectrum Cephalosporins, Fluoroquinolons and Imipenem.