Advances in Clinical and Experimental Medicine

Title abbreviation: Adv Clin Exp Med
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ISSN 1899–5276 (print)
ISSN 2451-2680 (online)
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Advances in Clinical and Experimental Medicine

2010, vol. 19, nr 2, March-April, p. 155–162

Publication type: original article

Language: English

Antibiotic Susceptibility Levels of Clinical Enterococcus spp. Strains, Including Those Resistant to Glycopeptides and High Concentrations of Aminoglycosides

Ocena stopnia wrażliwości na antybiotyki klinicznych szczepów z rodzaju Enterococcus, w tym opornych na glikopeptydy i duże stężenia aminoglikozydów

Beata Kowalska-Krochmal1,, Ewa Dworniczek1,, Izabela Dolna1,, Alicja Seniuk1,, Jacek Bania2,, Ewa Wałecka2,, Ewa Wrzyszcz1,

1 Department of Microbiology, Wroclaw Medical University, Poland

2 Department of Food Hygiene and Consumer Health Care, Wroclaw University of Environmental and Life Sciences, Poland


Background. The increased proportion of enterococci in infections and their growing resistance to antibiotics call for the need to ensure constant monitoring of the microorganisms’ sensitivity.
Objectives. To assess the degree of sensitivity of clinical Enterococcus species to antibiotics.
Material and Methods. The MIC values of five antibiotics (ampicillin, tetracycline, norfloxacin, vancomycin, teicoplanin) were determined using the agar dilution method and the E-test for 300 Enterococcus strains, including 191 E. faecalis and 109 E. faecium strains. Enterococcal resistance to high concentrations of gentamicin was determined using the disk-diffusion method.
Results. Among the 300 tested Enterococcus strains there were 28 glycopeptide-resistant enterococci (GRE) strains (9.3%), including 26 E. faecium and 2 E. faecalis strains; 57.6% of the strains were high-level gentamicin resistant (HLGR) strains, constituting 85% of the E. faecium group and 42% of the E. faecalis group. The MIC50 and MIC90 values (in μg/ml) of the five tested antibiotics for the E. faecalis and E. faecium strains were, respectively, ampicillin: 0.5 and 2 (E. faecalis), 12 and > 256 (E. faecium); tetracycline: 32 and 128, 1 and 12; norfloxacin: 4 and 256, > 256 and > 256; vancomycin: 1 and 2, 2 and 256; and teicoplanin: 0.5 and 1, 0.75 and 3. The MICs of vancomycin and teicoplanin of the GRE strains were, respectively, ≥128 and ≥32 for E. faecium and > 256 and ≥ 48 for E. faecalis.
Conclusion. The considerable sensitivity of the E. faecium strains to tetracycline, including also GRE and HLGR strains, creates a possibility to use antibiotics of the tetracycline group in the treatment of infections caused by strains of that species.


Wprowadzenie. Wzrastający udział enterokoków w zakażeniach i ich narastająca oporność na antybiotyki stwarza konieczność stałego monitorowania wrażliwości tych drobnoustrojów.
Cel pracy. Ocena stopnia wrażliwości na antybiotyki klinicznych szczepów Enterococcus.
Materiał i metody. Określono metodą seryjnych rozcieńczeń w agarze i metodą E-testów wartość MIC 5 antybiotyków (ampicylina, tetracyklina, norfloksacyna, wankomycyna, teikoplanina) dla 300 badanych szczepów paciorkowców z rodzaju Enterococcus, w tym 191 E. faecalis i 109 E. faecium. Metodą dyfuzyjno-krążkową oceniono oporność enterokoków na duże stężenia gentamycyny.
Wyniki. Wśród 300 badanych enterokoków było 28 szczepów GRE (9,3%), w tym 26 E. faecium i 2 E. faecalis. Stwierdzono 57,6% szczepów HLGR, w grupie E. faecium stanowiły one 85%, a w grupie E. faecalis – 42%. Wartości MIC50 i MIC90 5 badanych antybiotyków dla szczepów E. faecalis oraz E. faecium wynosiły odpowiednio: ampicylina 0,5 i 2 μg/ml; 12 i > 256 μg/ml, tetracyklina 32 i 128 μg/ml; 1 i 12 μg/ml, norfloksacyna 4 i 256 μg/ml; > 256 i > 256 μg/ml, wankomycyna 1 i 2 μg/ml; 2 i 256 μg/ml, teikoplanina 0,5 i 1 μg/ml; 0,75 i 3 μg/ml. Wartość MIC wankomycyny i teikoplaniny szczepów GRE wynosiła odpowiednio: ≥ 128 i ≥32 μg/ml dla E. faecium oraz > 256 i ≥48 μg/ml dla E. faecalis.
Wnioski. Znacząca wrażliwość na tetracyklinę szczepów E. faecium, w tym także GRE i HLGR, stwarza możliwość zastosowania antybiotyków z grupy tetracyklin w leczeniu zakażeń wywołanych przez szczepy tego gatunku.

Key words

Enterococcus spp., minimal inhibitory concentration of antibiotics, GRE, HLAR

Słowa kluczowe

Enterococcus spp., minimalne stężenie hamujące antybiotyku, GRE, HLAR

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