Browsing by Author "Dakić, Ivana (7801457313)"

The tube test and the microtiter-plate test are the most frequently used techniques for quantifying biofilm formation, an important indicator for the pathogenicity of staphylococci. The purpose of the present study was to develop a modified microtiter-plate technique for quantification of biofilm formation. This technique involves fixing the bacterial film with methanol, staining with crystal violet, releasing the bound dye with 33% glacial acetic acid, and measuring the optical density (OD) of the solution at 570 nm by using an enzyme immunosorbent assay reader. Biofilm formation of 30 Staphylococcus strains was estimated by the tube test, the standard microtiter-plate test and the modified microtiter-plate test. The modified microtiter-plate test, as a quantitative assay, is superior to the tube test in terms of objectivity and accuracy. It is also superior to the standard microtiter-plate test because it enables indirect measuring of bacteria attached both to the bottom and to the walls of the wells, while in the standard test only the dye bound to the bacteria adhered to the bottom of the wells is spectrophotometrically registered. Highly significant differences between OD values obtained by the standard microtiter-plate test and those obtained by the modified test suggest that large number of bacteria were attached to the walls of the wells. Therefore, the modification of the standard microtiter-plate test by introduction of an additional step of decolorization by acetic acid seems to be a useful improvement of the technique. © 2000 Elsevier Science B.V.

The tube test and the microtiter-plate test are the most frequently used techniques for quantifying biofilm formation, an important indicator for the pathogenicity of staphylococci. The purpose of the present study was to develop a modified microtiter-plate technique for quantification of biofilm formation. This technique involves fixing the bacterial film with methanol, staining with crystal violet, releasing the bound dye with 33% glacial acetic acid, and measuring the optical density (OD) of the solution at 570 nm by using an enzyme immunosorbent assay reader. Biofilm formation of 30 Staphylococcus strains was estimated by the tube test, the standard microtiter-plate test and the modified microtiter-plate test. The modified microtiter-plate test, as a quantitative assay, is superior to the tube test in terms of objectivity and accuracy. It is also superior to the standard microtiter-plate test because it enables indirect measuring of bacteria attached both to the bottom and to the walls of the wells, while in the standard test only the dye bound to the bacteria adhered to the bottom of the wells is spectrophotometrically registered. Highly significant differences between OD values obtained by the standard microtiter-plate test and those obtained by the modified test suggest that large number of bacteria were attached to the walls of the wells. Therefore, the modification of the standard microtiter-plate test by introduction of an additional step of decolorization by acetic acid seems to be a useful improvement of the technique. © 2000 Elsevier Science B.V.

This study investigated the prevalence of aminoglycoside resistance and genes encoding aminoglycoside-modifying enzymes in members of the Staphylococcus sciuri group. A total of 304 S. sciuri group member isolates (284 S. sciuri, 12 S. lentus, and 8 S. vitulinus) from humans (n = 34), animals (n = 133), and environmental sources (n = 137; out-hospital and hospital environment, food) were examined for their susceptibility to amikacin, gentamicin, isepamicin, kanamycin, neomycin, netilmicin, sisomicin, streptomycin, and tobramycin. The overall prevalence of resistance to aminoglycosides was low at 12.1%. Resistance to single aminoglycosides ranged from 0% to 7.2%. The aac(6′)-Ie/ aph(2″), ant(4′)-Ia, and aph(3′)-IIIa genes, either alone or in combination, were found in 16 out of 19 isolates showing resistance to nonstreptomycin aminoglycosides. Among the 22 isolates that showed resistance to streptomycin, the genes str and ant(6)-Ia were identified in 18 and 4 isolates, respectively. © Mary Ann Liebert, Inc.

This study investigated the prevalence of aminoglycoside resistance and genes encoding aminoglycoside-modifying enzymes in members of the Staphylococcus sciuri group. A total of 304 S. sciuri group member isolates (284 S. sciuri, 12 S. lentus, and 8 S. vitulinus) from humans (n = 34), animals (n = 133), and environmental sources (n = 137; out-hospital and hospital environment, food) were examined for their susceptibility to amikacin, gentamicin, isepamicin, kanamycin, neomycin, netilmicin, sisomicin, streptomycin, and tobramycin. The overall prevalence of resistance to aminoglycosides was low at 12.1%. Resistance to single aminoglycosides ranged from 0% to 7.2%. The aac(6′)-Ie/ aph(2″), ant(4′)-Ia, and aph(3′)-IIIa genes, either alone or in combination, were found in 16 out of 19 isolates showing resistance to nonstreptomycin aminoglycosides. Among the 22 isolates that showed resistance to streptomycin, the genes str and ant(6)-Ia were identified in 18 and 4 isolates, respectively. © Mary Ann Liebert, Inc.

In this paper we report on an experimental evaluation of phenotypic and molecular methods as means for the detection of oxacillin resistance in members of the Staphylococcus sciuri group. A total of 109 S. sciuri group member isolates (92 S. sciuri isolates, 9 S. lentus isolates, and 8 S. vitulinus isolates) were tested by the disk diffusion method, the agar dilution method, the oxacillin salt-agar screening method, slide latex agglutination for PBP 2a, and PCR assay for mecA as the reference method. The mecA gene was detected in 29 S. sciuri isolates, and the true-positive and true-negative results of the other tests were defined on the basis of the presence or the absence of the mecA gene. For the different methods evaluated, the sensitivities and specificities were as follows: for the disk diffusion test with a 1-μg oxacillin disk, 100% and 55.9%, respectively; for the disk diffusion test with a 30-μg cefoxitin disk, 93.5% and 100%, respectively; for the agar dilution method, 100% and 50%, respectively; for the oxacillin salt-agar screen test (with 6 μg of oxacillin per ml and 4% NaCl) 100% and 100%, respectively; and for the slide latex agglutination test for PBP 2a, 100% and 100%, respectively. The disk diffusion test with various β-lactam antibiotics was performed to evaluate their use for the prediction of oxacillin resistance. The results indicate that meropenem, cefazolin, cefamandole, cefuroxime, cefotetan, cefoperazone, cefotaxime, ceftriaxone, moxalactam, cefaclor, and cefprozil may be used as surrogate markers of oxacillin resistance, although further studies of their use for the detection of oxacillin resistance are required. Copyright © 2006, American Society for Microbiology. All Rights Reserved.

A total of 28 staphylococcal isolates from human clinical specimens belonging to the Staphylococcus sciuri group were identified and characterized. The API Staph and ID32 STAPH correctly identified S. sciuri and S. lentus but not S. vitulinus strains. Identification to the subspecies level was possible only by a PCR-based method.

Staphylococcus sciuri is a principally animal-associated bacterial species, but its clinical relevance for humans is increasing. Our study aimed to provide the first insight into the prevalence of this bacterium in a hospital environment. A 3-month surveillance was conducted in a hospital located in Belgrade, Serbia, and 1,028 samples taken from hands of medical personnel, medical devices, and various hospital surfaces were screened for S. sciuri presence. In total, 108 isolates were obtained, which resulted in a relatively high rate of colonization (10.5%). These isolates, along with 7 S. sciuri strains previously isolated in the same hospital (n = 115), were phenotypically and genotypically characterized. Antimicrobial susceptibility testing revealed that 73% of the strains were resistant to one or more antibiotics, with 4.3% strains displaying multiresistance. Examination of 16S-23S ribosomal DNA intergenic spacer length polymorphism identified the strains at the subspecies level, and 74 (64.3%) strains of S. sciuri subsp. sciuri, 37 (32.2%) strains of S. sciuri subsp. rodentium, and 4 (3.5%) strains of S. sciuri subsp. carnaticus were established. Pulsed-field gel electrophoresis (PFGE) analysis showed 21 distinct pulsotypes, including 17 main types and 4 subtypes. One dominant cluster with 62 strains was found, while 19 (90.5%) of the PFGE types and subtypes identified had 5 or fewer strains. The predominance of small PFGE clusters suggests that the ubiquitous presence of S. sciuri in the outside environment presents the continuous source for colonization of the hospital environment. The presence of one dominant PFGE cluster of strains indicates that some S. sciuri strains may be capable for adaptation to hospital environment conditions and continuous existence in this environment. Copyright © 2005, American Society for Microbiology. All Rights Reserved.

During a 3-year study period, 32,741 urine samples were analyzed for the presence of members of the Staphylococcus sciuri group (S. sciuri, S. lentus, and S. vitulinus), and 13 isolates were identified. They presented 0.79% of the total number of coagulase-negative staphylococci isolated. One case of symptomatic urinary tract infection and five possible cases of asymptomatic bacteriuria caused by these bacteria were established. It is noteworthy, however, that over 50% of the isolates originated from hospitalized patients.

[No abstract available]

This study aimed to characterize the resistance profiles of the Staphylococcus sciuri group members to macrolides, lincosamides, streptogramins (MLS antibiotics), and linezolid upon analysis of large series of isolates that included 162 S. sciuri isolates, nine S. lentus, and one S. vitulinus. The evaluation of their susceptibility by disk diffusion and agar dilution methods, along with PCR detection of the resistance genes erm(A), erm(R), erm(C), mef(A), lnu(A), and lnu(B), were performed. Resistance to macrolides was detected in 10 (5.8%) tested strains, with three and six isolates exhibiting constitutive and inducible MLSB resistance phenotypes, respectively. Resistance mediated by active efflux was detected in one strain. The presence of genes conferring resistance, namely erm(B) or erm(C), was detected in two strains. All tested strains were susceptible to pristinamycin and linezolid. Of 172 tested strains, 70.9% were resistant and 26.2% had intermediary resistance to lincomycin, whereas 1.7% were resistant and 50% had intermediary resistance to clindamycin. The lnu(A) gene was detected in two strains only. The great majority of the tested S. sciuri strains (153 out of 162; 94.4%) presumably exhibited LSA phenotype because they did not carry lnu genes nor displayed constitutive MLSB resistance, but still showed intermediate resistance or resistance to lincomycin (MICs of 4, 8, 16, and 32 μg/ml). The results obtained indicate that S. sciuri may be naturally resistant to lincomycin. Expression of a novel type of inducible resistance to lincosamides, induced by erythromycin in erythromycin-susceptible strains, was observed in the S. sciuri group isolates. © Mary Ann Liebert, Inc.

This study aimed to characterize the resistance profiles of the Staphylococcus sciuri group members to macrolides, lincosamides, streptogramins (MLS antibiotics), and linezolid upon analysis of large series of isolates that included 162 S. sciuri isolates, nine S. lentus, and one S. vitulinus. The evaluation of their susceptibility by disk diffusion and agar dilution methods, along with PCR detection of the resistance genes erm(A), erm(R), erm(C), mef(A), lnu(A), and lnu(B), were performed. Resistance to macrolides was detected in 10 (5.8%) tested strains, with three and six isolates exhibiting constitutive and inducible MLSB resistance phenotypes, respectively. Resistance mediated by active efflux was detected in one strain. The presence of genes conferring resistance, namely erm(B) or erm(C), was detected in two strains. All tested strains were susceptible to pristinamycin and linezolid. Of 172 tested strains, 70.9% were resistant and 26.2% had intermediary resistance to lincomycin, whereas 1.7% were resistant and 50% had intermediary resistance to clindamycin. The lnu(A) gene was detected in two strains only. The great majority of the tested S. sciuri strains (153 out of 162; 94.4%) presumably exhibited LSA phenotype because they did not carry lnu genes nor displayed constitutive MLSB resistance, but still showed intermediate resistance or resistance to lincomycin (MICs of 4, 8, 16, and 32 μg/ml). The results obtained indicate that S. sciuri may be naturally resistant to lincomycin. Expression of a novel type of inducible resistance to lincosamides, induced by erythromycin in erythromycin-susceptible strains, was observed in the S. sciuri group isolates. © Mary Ann Liebert, Inc.

We describe a case of surgical wound infection due to Staphylococcus sciuri. The isolated strain was susceptible to trimethoprim-sulfamethoxazole, erythromycin, chloramphenicol, ciprofloxacin and vancomycin and resistant to gentamicin, clindamycin, rifampicin, methicillin, ampicillin and ceftriaxone. The multiresistance of the strain had a serious impact on the prolonged course of the infection. Although this bacterium is principally found in animals, our strain was probably of nosocomial origin.

We describe a case of surgical wound infection due to Staphylococcus sciuri. The isolated strain was susceptible to trimethoprim-sulfamethoxazole, erythromycin, chloramphenicol, ciprofloxacin and vancomycin and resistant to gentamicin, clindamycin, rifampicin, methicillin, ampicillin and ceftriaxone. The multiresistance of the strain had a serious impact on the prolonged course of the infection. Although this bacterium is principally found in animals, our strain was probably of nosocomial origin.

Genes encoding Staphylococcal enterotoxins (sea to see, seg, and seh), toxic shock syndrome toxin 1 (tst), and exfoliative toxins (eta and etb) were not detected in a large panel of 48 Staphylococcus sciuri group isolates tested. This strongly suggests that production of the Staphylococcal exotoxins by these bacteria is highly unlikely. Copyright © 2005, American Society for Microbiology. All Rights Reserved.

[No abstract available]