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Introduction. Klebsiella pneumoniae is one of the leading causes of serious hospital-acquired infections worldwide among Enterobacteriaceae species. It is the most common producer of carbapenemases in many parts of the world. Objective. The aim of the study was to determine which enzymes were responsible for resistance to carbapenems in Klebsiella pneumoniae strains isolated at the Centre of Microbiology of Public Health Institute of Vojvodina. Methods. A total of 29 Klebsiella pneumoniae non-duplicated strains resistant to at least one carbapenem isolated from clinical samples of hospitalized patients between November 1st 2013 and April 30th 2014 were studied. The species identification and susceptibility were done using VITEK 2 (bioMйrieux, Marcy-l’Йtoile, France) system. Phenotypic conformation of carbapenemase production was done by double-disc synergy test. PCR technique was performed for detection of genes encoding production of carbapenemases (blsKPC, blaVIM, bla NDM, blaOXA-48). Results. Isolates of Klebsiella pneumoniae resistant to at least one carbapenem showed positive on double- disc synergy test between meropenem and dipicolinic acid. All strains positive in phenotypic test contained blaNDM gene. In isolates resistant only to ertapenem, neither production of carbapenemases nor presence of genes encoding these enzymes were detected. Among these isolates, nine produced extended-spectrum β-lactamase. Conclusion. The presence of NDM metallo-β-lactamase was determined in all Klebsiella pneumoniae isolates resistant to at least one carbapenem.

Listeria monocytogenes is pathogenic bacterium that can contaminate food products during and after processing. As ready-to-eat food does not undergo any treatment to ensure its safety before consumption, the risk of foodborne disease must be considered if this pathogen is present in the food. As diseases caused by contaminated food are an important public health problem today, the aim of this study was to determine the prevalence of Listeria monocytogenes in different ready-to-eat food products. In the seven-month period from June 1 to December 31, 2011, a total of 1 380 food samples were examined in the Division of Sanitary Bacteriology, Center for Microbiology, Institute of Public Health of Vojvodina in Novi Sad. A total of 912 samples were analyzed for the presence of Listeria monocytogenes according to ISO 11290-2. The identity of suspected Listeria monocytogenes was confirmed using the VITEK 2 Compact system (BioMerieux, France). Out of 912 samples, Listeria monocytogenes was detected in 18 (1.97%). Listeria monocytogenes was mostly found in cooked meals (in 6 samples out of 18), sandwiches (4 samples) and frozen food, such as ice-cream and frozen vegetables (4 samples). It was also found in tofu bread spreads (2 samples), cream cheese (1 sample) and cakes (1 sample). The presence of Listeria monocytogenes in some ready-to-eat food could present a public health hazard, particularly to the high-risk population group, because of the high mortality rate associated with listeriosis and the widespread nature of the organism. Monitoring of listeriosis is essential to prevent foodborne outbreaks, and in assessing human health risk in ready-to-eat foods.

Clostridium difficile-associated diarrhea (CDAD) has been recognized as the leading cause of diarrhea worldwide. In the last five years, it has become the leading cause of diarrhea in the Clinical Center of Vojvodina (CCV) as well. The aim of this study was to determine the epidemiology and total cost of treatment for all patients with Clostridium difficile-associated diarrhea hospitalized at the Infectious Disease Clinic of the CCV; to analyze the costs of treatment with regard to therapeutic approach; to compare the costs of treatment in each year of the investigated period related to the number of patients, and to analyze the outcome of treatment. The study was retrospective, and the data were collected from the medical records of 472 patients with Clostridium difficile diarrhea treated from 2008 to 2012 and analyzed. Of the total 472 patients with CDAD, 54.23% were female and the average age was 65.84. A statistically significant majority of them had been previously treated in other hospitals and a minority in ambulatory settings (395 inpatients vs. 77 outpatients, p=0.000, p

The aim of this study is to determine the prevalence of extended spectrum beta-lactamase (ESBL) producing Klebsiella pneumoniae strains isolated from blood in children and their susceptibility to antimicrobial drugs commonly used in the therapy. The study was conducted at the Institute of Public Health of Vojvodina Province, Serbia, in a two-year period, from January 2009 to December 2010. A total of 424 non-duplicate strains were isolated from the blood of pediatric patients hospitalized in various wards in the Institute of Health Care of Children and Youth of Vojvodina Province. Fifty isolates of Klebsiella pneumoniae were reported. The frequency of isolation of Klebsiella pneumoniae was 27/222 (12.2%) and 23/202 (11.3%) isolates in 2009 and 2010, respectively. There was a high prevalence of ESBL-producing Klebsiella pneumoniae, 76% (38/50), and 17 isolates (44.7%) were multidrug resistant (MDR). Further drug resistance surveillance in hospitals and the molecular characterization of ESBL-positive isolates in our country is necessary.

The aim of this study was, for the first time in our country, to identify the capability of isolates of Sphingomonas paucimobilis to form a biofilm. In the 3-month period from January 1st to March 31st 2010, a total of 2630 samples of drinking water were microbiologically examined in the Institute of Public Health of Vojvodina, Serbia. From all examined samples of drinking water, non-fermentative Gram-negative oxidase positive bacilli were identified in 113 samples (4.30%). The bacteria isolates were identified as Sphingomonas paucimobilis (4 isolates), based on analysis by the automated VITEK 2 Compact system; biofilm formation was examined according to the modified method of Stepanović et al. (2000). All 4 Sphingomonas paucimobilis strains tested showed a strong biofilm-producing ability. Considering the potential pathogenic features of Sphingomonas paucimobilis, the presence of these strains in drinking water distribution systems is not desirable. Therefore, adequate biofilm degradation and management of drinking-water distribution networks that will guarantee microbiologically safe drinking water is recommended.

Candidemia is an important emerging nosocomial infection in patients with risk factors. Candida species from nonsterile sites can give insight into the characteristics of strains that may cause invasive disease. The aim of this study was to evaluate antifungal susceptibility of Candida blood and fecal isolates in Novi Sad, Vojvodina. During a 3-year period (2008 to 2010), 424 isolates of Candida spp. were collected, 30 bloodstream isolates and 394 strains from fecal samples. In vitro susceptibility of these isolates to five antifungal agents was established using commercial ATB FUNGUS 3 (Bio-Mérieux). Predominant species was Candida albicans (6 isolates from blood and 269 from feces). Resistance to one or more antifungal agents was less common in Candida albicans (3.63%) than in other species (24.83%). Resistance to itraconazole was the most commonly found in both groups of isolates, 9.64% strains from feces and 20% from blood samples. Twelve isolates were multiply resistant, usually to fluconazole, itraconazole, and voriconazole. Resistance to amphotericine B was extremely rare. Although resistance to antimycotics of Candida spp. is rare at present, continued surveillance of antifungal susceptibility is necessary in order to monitor trends, and to choose the right empiric therapy.

Quinolone antibiotics have been widely used in human and veterinary medicine. This has caused the development of resistance and difficulties in the treatment of complicated bacterial infections in humans. The resistance to quinolones develops due to chromosome mutations and it can also be transferred by plasmids. The target enzyme for quinolones in Gram-negative bacteria is Gyrasa A, while the target enzyme in Grampositive bacteria is mostly topoisomerase IV. Gyrase A consists of two subunits encoded by genes gyrA and gyrB. The function of the enzyme is to introduce negative super coiling in DNA and therefore is essential for the replication of bacteria. Quinolone resistance develops if point mutations at 83 and/or 87 codon are introduced on gyrA. Establishing a minimal inhibitory concentration (MIC) to this group of antimicrobials will reveal possible mutations. Recently it was discovered that quinolone resistance is transmittable by plasmid termed PMQR (plasmid mediated quinolone resistance). The target gene marked qnr encodes a pentapeptide repeat family protein. Pentapeptide repeats form sheets, involved in protein-protein interactions. Qnr protein binds to GyrA protecting the enzyme from the inhibitory effect of ciprofloxacin. The distribution of qnr related resistance is higher in humans than in animals. In poultry, however, this type of resistance is present more than in other animals. Plasmid mediated resistance contributes to the faster spread of quinolone resistance. Proper food handling will significantly contribute to decreasing the risk from infection to which people are exposed. In medical and veterinary laboratories antimicrobial resistance monitoring in clinical and environmental isolates is advised. Since correlation between antibiotics application and antimicrobial resistance is often suggested, antimicrobial use must be under strict control of the authorities both in human and in veterinary medicine. .

Background/Aim. Carbapenem resistance has escalated in medically important enterobacteria such as Klebsiella pneumoniae and Escherichia coli worldwide. Multidrug-resistant strains represent an important source of concern as effective therapeutic options of infections they cause are limited or none. There were no comprehensive studies considering the presence of carbapenemase production in enterobacteria in Serbia so far. The aim of the study was to determine carbapenemase production in hospital isolates of multidrug-resistant K. pneumoniae and E. coli in Serbia. Methods. Strains of K. pneumoniae and E. coli resistant to at least one carbapenem (imipenem, meropenem, ertapenem) were collected from November 2013 to May 2014. Isolates were obtained from clinical samples of patients treated in 14 hospitals in Serbia. Carbapenem resistance was confirmed using phenotypic tests and polymerase chain reaction (PCR) in National Reference Laboratory for Registration and Surveillance of Antimicrobial Resistance of Bacterial Strains in Novi Sad. Results. Of 129 collected strains, 121 (93.8%) were K. pneumoniae and 8 (6.2%) were E. coli. Seventy (54.3%) strains were obtained from urine, 26 (20.2%) from blood, 19 (14.7%) from wound secretions and 14 (10.9%) from lower respiratory tract secretions. Carbapenemase genes were detected in 58 (45%) isolates. The gene bla New Delhi-metallo-beta-lactamases (blaNDM) was found in 33 (27.3%) K. pneumoniae, bla oxacillinases-48 (blaOXA-48) in 10 (8.3%), bla K. pneumonia carbapenemase (blaKPC) in 1 (0.8%), and 7 (5.4%) strains harbored both blaOXA-48 and blaNDM. Seven E. coli harbored blaNDM gene. Conclusion. In Serbia, the most common type of carbapenemase in both multidrug-resistant K. pneumoniae and E. coli is NDM. Co-production of OXA-48 and NDM was found in K. pneumoniae. To our knowledge, KPC production was detected for the first time in Serbia. [ABSTRACT FROM AUTHOR]

Candidemia is an important emerging nosocomial infection in patients with risk factors. Candida species from nonsterile sites can give insight into the characteristics of strains that may cause invasive disease. The aim of this study was to evaluate antifungal susceptibility of Candida blood and fecal isolates in Novi Sad, Vojvodina. During a 3-year period (2008 to 2010), 424 isolates of Candida spp. were collected, 30 bloodstream isolates and 394 strains from fecal samples. In vitro susceptibility of these isolates to five antifungal agents was established using commercial ATB FUNGUS 3 (Bio-Mérieux). Predominant species was Candida albicans (6 isolates from blood and 269 from feces). Resistance to one or more antifungal agents was less common in Candida albicans (3.63%) than in other species (24.83%). Resistance to itraconazole was the most commonly found in both groups of isolates, 9.64% strains from feces and 20% from blood samples. Twelve isolates were multiply resistant, usually to fluconazole, itraconazole, and voriconazole. Resistance to amphotericine B was extremely rare. Although resistance to antimycotics of Candida spp. is rare at present, continued surveillance of antifungal susceptibility is necessary in order to monitor trends, and to choose the right empiric therapy. [ABSTRACT FROM AUTHOR]

Introduction Enterococci are important hospital-acquired pathogens. The most commonly isolated species of the genus, Enterococcus faecalis and Enterococcus faecium are the third to fourth-most prevalent nosocomial pathogens worldwide. The aim of this study was to determine the frequency of resistance to vancomycin and other antimicrobial agents of Enterococcus spp strains isolated from blood cultures of hospitalized patients. Material and methods During the three-year period, from 2008 to 2010, 132 strains of Enterococcus spp isolated from blood cultures of hospitalized patients were tested for their susceptibility to ampicillin, vancomycin, gentamycin (high-level resistance), erythromycin, chloramphenicol, teicoplanin, ciprofloxacin by disc diffusion method according to the Clinical and Laboratory Standards Institute recommendations. Susceptibility of vancomycin resistant E. faecium to the same antibiotics and to linezolid, quinopristin/dalfopristin and tigecyclin was determined using VITEK system. Results and discussion Resistance to vancomycin was detected in 21 (15.9%) Enterococcus spp strains. The percentage of resistance to other antimicrobial agents varied from 23.1% for chloramphenicol to 81.3% for ciproflxacin. All vancomycin resistant enterococci were identified as E. faecium and belonged to phenotype VanA. The resistance to other antibiotics was very high, except for linezolid and quinopristin/dalfopristin (4.7%). The high-level aminoglycoside resistance was 87.6% for gentamycin and 95.2% for streptomycin. All isolates were resistant to ampicillin, teicoplanin and ciprofloxacin. Conclusion The detected high frequency of multidrug-resistant isolates among vancomycin resistant enterococci is of great importance and suggests the need for further monitoring of susceptibility in order to take adequate measures to prevent and control spreading of resistant strains. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction Acinetobacter spp has become an important cause of nosocomial infections due to its great ability to survive and spread in a hospital setting and to develop resistance to many antibiotics. The aim of this study was to examine the resistance to carbapenems and other commonly used antibiotics in strains of Acinetobacter isolated from wound swabs. Material and Methods In the Laboratories of Microbiology Center at the Institute for Public Health in Novi Sad wound swabs were taken from the patients hospitalized at the Institutes and Departments of the Clinical Center of Vojvodina in Novi Sad. A total of 271 Acinetobacter spp strains were tested to susceptibility on carbapenems and other most commonly used antibiotics by disk diffusion method according to the recommendation of the Clinical and Laboratory Standards Institute. Results and Discussion Acinetobacter spp (271 isolates) developed resistance to imipenem and meropenem (67.4% and 64.4%). The resistance to both cephalosporins III and IV generation and ciprofloxacin was 100%. The resistance to ampicillin-sulbactam was 71.4%. Conclusion Our results show high resistance to carbapenems in Acinetobacter spp strains isolated from wound swabs. These facts suggest the need for continuous monitoring of susceptibility in order to take adequate measures to prevent and control spreading of resistant strains. [ABSTRACT FROM AUTHOR]

Introduction: Acinetobacter spp has become an important cause of nosocomial infections due to its great ability to survive and spread in a hospital setting and to develop resistance to many antibiotics. The aim of this study was to examine the resistance to carbapenems and other commonly used antibiotics in strains of Acinetobacter isolated from wound swabs., Material and Methods: In the Laboratories of Microbiology Center at the Institute for Public Health in Novi Sad wound swabs were taken from the patients hospitalized at the Institutes and Departments of the Clinical Center of Vojvodina in Novi Sad. A total of 271 Acinetobacter spp strains were tested to susceptibility on carbapenems and other most commonly used antibiotics by disk diffusion method according to the recommendation of the Clinical and Laboratory Standards Institute., Results and Discussion: Acinetobacter spp (271 isolates) developed resistance to imipenem and meropenem (67.4% and 64.4%). The resistance to both cephalosporins III and IV generation and ciprofloxacin was 100%. The resistance to ampicillin-sulbactam was 71.4%., Conclusion: Our results show high resistance to carbapenems in Acinetobacter spp strains isolated from wound swabs. These facts suggest the need for continuous monitoring of susceptibility in order to take adequate measures to prevent and control spreading of resistant strains.

Introduction: Enterococci are important hospital-acquired pathogens. The most commonly isolated species of the genus, Enterococcus faecalis and Enterococcus faecium are the third to fourth-most prevalent nosocomial pathogens worldwide. The aim of this study was to determine the frequency of resistance to vancomycin and other antimicrobial agents of Enterococcus spp strains isolated from blood cultures of hospitalized patients., Material and Methods: During the three-year period, from 2008 to 2010, 132 strains of Enterococcus spp isolated from blood cultures of hospitalized patients were tested for their susceptibility to ampicillin, vancomycin, gentamycin (high-level resistance), erythromycin, chloramphenicol, teicoplanin, ciprofloxacin by disc diffusion method according to the Clinical and Laboratory Standards Institute recommendations. Susceptibility of vancomycin resistant E. faecium to the same antibiotics and to linezolid, quinopristin/dalfopristin and tigecyclin was determined using VITEK system., Results and Discussion: Resistance to vancomycin was detected in 21 (15.9%) Enterococcus spp strains. The percentage of resistance to other antimicrobial agents varied from 23. l% for chloramphenicol to 81.3% for ciproflxacin. All vancomycin resistant enterococci were identified as E. faecium and belonged to phenotype VanA. The resistance to other antibiotics was very high, except for linezolid and quinopristin/dalfopristin (4.7%). The high-level aminoglycoside resistance was 87.6% for gentamycin and 95.2% for streptomycin. All isolates were resistant to ampicillin, teicoplanin and ciprofloxacin., Conclusion: The detected high frequency of multidrug-resistant isolates among vancomycin resistant enterococci is of great importance and suggests the need for further monitoring of susceptibility in order to take adequate measures to prevent and control spreading of resistant strains.

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).

Introduction: Staphylococcus aureus is a major cause of both hospital- and community-acquired infections worldwide. Since the introduction of methicillin into clinical use, methicillin-resistant S. aureus strains have emerged with increasing frequency throughout the world. The aim of the study was to determine frequency of resistance to methicillin and other most commonly used antibiotics of S aureus strains isolated from hospitalized patients., Material and Methods: During the period 1.1.-31. 12. 2007, 226 strains of S. aureus isolated from hospitalized patients were tested for their susceptibility to penicillin, methicillin, erythromycin, clindamycin, gentamycin, sulfamethoxazolle-trimethoprim, fusidic acid and vancomycin using disc diffusion technique., Results: Resistance to methicillin was detected in 20 (7.5%) S. aureus strains. All of them were susceptible to vancomycin. The resistance to other antimicrobial agents varied from 5% for sulfamethoxazolle-trimethoprim to 75% to gentamycin. Among methicillin susceptible strains, high resistance (84.1%) was found to penicillin only The resistance to other antimicrobial agents was low, ranging from 0 for fusidic acid and vancomycin to 12.2% for gentamycin., Conclusion: Our results show low rate of methicillin-resistant S. aureus strains compared to other authors "findings, but also the presence of multidrug-resistant isolates and isolates susceptible to vancomycin only These facts suggest the need for further monitoring of susceptibility in order to take adequate measures to prevent and control spreading of resistant strains.