7 research outputs found
Phenotypes and genotypes of macrolide-resistant Streptococcus pneumoniae in Serbia
Although macrolides are widely used for treating pneumococcal infections, an
increase in macrolide resistance might compromise their use. The objective of
this study was to determine the prevalence of macrolide-resistant phenotypes
and genotypes in macrolide-resistant S. pneumoniae isolates in Serbia. A
total of 228 macrolide-resistant strains isolated during the period of
2009-2012, were analyzed. Macrolide resistance phenotypes were determined by
a double disk diffusion test. The presence of macrolide resistance genes was
detected by PCR. Antibiotics susceptibilities were tested using the VITEK2
system and E test. Among the examined isolates, the MLSB phenotype which is
linked to the presence of the erm(B) gene dominated (83.3%), while the mef(A)
gene which is associated with the M phenotype, was identified in 16.7%
isolates. Over 40% of isolates expressed co-resistance to penicillin. A
multiple-resistant pattern was found in 36.4% strains, more frequently in
children. However, all strains were susceptible to telithromycin, vancomycin,
linezolid, fluoroquinolones and rifampicin. [Projekat Ministarstva nauke
Republike Srbije, br. 175039
Distribution of macrolide-resistant genes among isolates of macrolideresistant Streptococcus pyogenes and Streptococcus pneumoniae in Serbia
Macrolide resistance in Streptococcus pneumoniae and in group A streptococci
(GAS) is a significant problem worldwide. In Serbia, data on the mechanisms
of resistance and the corresponding resistance genes in streptococci are
largely lacking. Therefore, we analyzed the distribution of macrolide
resistance phenotypes and genotypes in 44 macrolideresistant GAS (MRGAS) and
50 macrolide-resistant S. pneumoniae (MRSP) isolates collected in the same
period. The double disk diffusion test and PCR were used to analyze
resistance phenotypes and resistance genes, respectively. Among MRSP, the
MLSB phenotype dominated, whereas the M phenotype was the most prevalent
among MRGAS isolates. Consequently, in MRSP, the ermB gene was the most
common (n=40, 80%), followed by the mefA gene (n=7,14%). In MRGAS strains,
mefA dominated (n=27,61%), followed by ermA (n=15, 33%) and ermB (n=3, 7%).
In 3 MRSP isolates no resistance genes were detected, while one MRGAS strain
with iMLSB phenotype harbored both ermA and mefA genes
The first nationwide multicenter study ofAcinetobacter baumanniirecovered in Serbia: emergence of OXA-72, OXA-23 and NDM-1-producing isolates
Background The worldwide emergence and clonal spread of carbapenem-resistantAcinetobacter baumannii(CRAB) is of great concern. The aim of this nationwide study was to investigate the prevalence of CRAB isolates in Serbia and to characterize underlying resistance mechanisms and their genetic relatedness. Methods Non-redundant clinical samples obtained from hospitalized patients throughout Serbia were included in the prospective, observational, multicenter study conducted from January to June 2018. Samples were initially screened for the presence ofAcinetobacter baumannii-calcoaceticus(Acb) complex using conventional bacteriological techniques. Acb complexes recovered from clinical samples obtained from inpatients with confirmed bacterial infections were further evaluated for the presence ofA. baumannii. Identification to the species level was done by the detection of thebla(OXA-51)gene andrpoBgene sequence analysis. Susceptibility testing was done by disk diffusion and broth microdilution method. CRAB isolates were tested for the presence of acquired carbapenemases(bla(OXA-24-like),bla(OXA-23-like,)bla(OXA-58-like),bla(OXA-143-like),bla(IMP),bla(VIM),bla(GIM),bla(SPM),bla(SIM),bla(NDM)) by PCR. Clonal relatedness was assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Results Acb complex was isolated in 280 out of 2401 clinical samples (11.6%). Overall,A. baumanniiwas identified in 237 out of 280 Acb complex (84.6%). CRAB prevalence was found to be 93.7% (237/222). The MIC50/MIC(90)for imipenem and meropenem were 8/ gt 32 mu g/mL and 16/ gt 32 mu g/mL, respectively. Although susceptibility was high for colistin (95.7%;n = 227) and tigecycline (75.1%;n = 178), ten isolates (4.3%) were classified as pandrug-resistant. The following carbapenemases-encoding genes were found: 98 (44.2%)bla(OXA-24-like), 76 (34.5%)bla(OXA-23-like), and 7 (3.2%)bla(NDM-1). PFGE analysis revealed six different clusters. MLST analysis identified three STs: ST2 (n = 13), ST492 (n = 14), and ST636 (n = 10). Obtained results evaluated that circulating CRAB clones in Serbia were as follows:bla(OXA66)/bla(OXA23)/ST2 (32.4%),bla(OXA66)/bla(OXA23)/bla(OXA72)/ST2 (2.7%),bla(OXA66)/bla(OXA72)/ST492 (37.8%), andbla(OXA66)/bla(OXA72)/ST636 (27.1%). Conclusion This study revealed extremely high proportions of carbapenem resistance amongA. baumanniiclinical isolates due to the emergence ofbla(OXA-72),bla(OXA-23), andbla(NDM-1)genes among CRAB isolates in Serbia and their clonal propagation
Invasive isolates of Streptococcus pneumoniae in Serbia: Antimicrobial susceptibility and serotypes
Introduction. Streptococcus pneumoniae is one of the leading causes of bacterial meningitis and sepsis. Invasive pneumococcal disease is a significant medical problem worldwide, particularly in children, due to a huge increase of pneumococcal resistance to antibiotics. Objective. The aim of the study was to investigate the antimicrobial susceptibility pattern of invasive pneumococcal isolates, as well as to determine whether decreased S. pneumoniae susceptibility to antibiotics was related to a particular serotype. Methods. Antimicrobial susceptibility to 19 antibiotics was determined in 58 invasive pneumococcal strains that were collected from seven regional centers during the period July 2009 to February 2011 in the National Reference Laboratory for streptococci and pneumococci. Results. The overall nonsusceptibility rate to penicillin was detected in 34% of pneumococcal isolates and to erythromycin in 36%. Higher resistance rates were observed among children than among adults. Penicillin resistance rate was 65% in children versus 22% in adults, while erythromycin nonsusceptibility rate was 47% in children versus 32% in adults. Co-resistance to penicillin and erythromycin was detected in 21% strains, mostly isolated from children. Multiresistance was found in one third of isolates. All strains were susceptible to vancomycin, linezolid, fluoroquinolones, telithromycin and rifampicin, while 23 (40%) isolates were susceptible to all tested antibiotics. The most common resistant serotypes were 19F and 14. Conclusion. The study has revealed that penicillin and macrolide resistance among invasive pneumococcal isolates is very high in Serbia. This emphasizes the need for continuous monitoring for invasive pneumococcal disease to document the serotype distribution and antimicrobial susceptibility pattern. [Projekat Ministarstva nauke Republike Srbije, br. 175039: Bakterije rezistentne na antibiotike u Srbiji - fenotipska i genotipska karakterizacija
Biofilm Production and Antimicrobial Resistance of Clinical and Food Isolates of Pseudomonas spp.
Due to its ubiquity, ability to form biofilms, and acquire resistance mechanisms, Pseudomonas spp. become one of the major
challenge for healthcare settings and food industry. The aims of this study were to assess the biofilm production of Pseudomonas
spp. recovered from clinical and food specimens and to evaluate their antimicrobial resistance. A total of 108
isolates of Pseudomonas spp. were included in the study, 48 being clinical isolates recovered from patients admitted to four
tertiary care hospitals throughout Serbia and 60 were isolated from the bulk tank milk samples and meat carcasses. Biofilm
production was analyzed by microtiter plate assay. Antimicrobial susceptibility was evaluated by disk diffusion method
according to the CLSI guidelines, while class A and B Ī²-lactamases encoding genes were screened by PCR. A total of 98
(90.7%) strains were biofilm producers (moderate producer: 68, 69.4%; strong producer: 8, 8.2%). Although a slightly higher
percentage of clinical isolates were biofilm producers (91.7%) compared to food isolates (90%), statistical significance was
not observed (P > 0.05). The proportion of carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates was significantly
higher among clinical (42%) isolates compared to food (1.7%) Pseudomonads (P < 0.05). The blaPER and blaNDM genes were
found in ESBL (seven isolates) and MBL (two isolates) production, respectively. In the present study, we confirmed that
biofilm formation was highly present in both clinical and food Pseudomonas spp. irrespective of the prior existence of resistance
genes. Additionally, clinical settings pose a major reservoir of MDR Pseudomonas spp. and especially CRPA isolates.We gratefully acknowledge the following persons for supplying the strains
used in this study: Snezana Jovanovic, Bojan Rakonjac, Momir Djuric,
Lidija Boskovic, Teodora Vitorovic, Snezana Delic, Branislava Kocic,
Dragana Andjelkovic
Streptococcus pneumoniae serotype distribution in Vojvodina before the introduction of pneumococcal conjugate vaccines into the national immunization program
Introduction. Streptococcus pneumoniae is the most common causative agent of
bacterial pneumonia and meningitis. Mandatory childhood immunization against
pneumococcal diseases is introduced in the new Law on Protection of
Population against Communicable Diseases in Serbia. Objective. The objective
of this study was to determine the prevalence of pneumococcal serotype
distribution in Vojvodina region before routine use of pneumococcal conjugate
vaccine in Serbia. Methods. A total of 105 isolates of Streptococcus
pneumoniae were collected in the period from January 2009 to April 2016.
Based on the results of serotyping in the National Reference Laboratory, we
analyzed distribution of circulating serotypes and coverage of conjugate and
23-valent polysaccharide pneumococcal vaccines in different age groups.
Results. Among 105 isolates, a total of 21 different serotypes of
Streptococcus pneumoniae were determined. The most frequent serotypes were 3
(21.9%), 19F (20.0%), and 14 (10.5%). The serotype coverage of pneumococcal
conjugate vaccines (PCV7, PCV10, and PCV13) was 48.6%, 54.3%, and 84.8%,
respectively, while pneumococcal polysaccharide vaccine (PPV23) covered 89.5%
of the total number of isolates in all age groups. Serotypes included in
PCV7, PCV10, and PCV13 represented 72.0%, 76.0%, and 88.0% of the total
number of isolates in children ā¤5 years, respectively. Vaccine serotype
coverage of PCV13 and PPV23 ranged from 87.1% to 90.3% in adults 50-64 years
of age, and 77.8% to 85.2% in adults ā„65 years old. Conclusion. Serotype
distribution of Streptococcus pneumoniae in the population fairly overlaps
with the serotypes contained in pneumococcal vaccines, so that implementation
of childhood immunization is justified. The study was done in the Province of
Vojvodina but the findings may be applied to Serbia as a whole. [Projekat
Ministarstva nauke Republike Srbije, br. ON 175039] <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/SARH1612678E">10.2298/SARH1612678E</a><u></b></font