Comparison of the effects in vitro of tea tree oil and plaunotol on methicillin-susceptible and methicillin-resistant strains of Staphylococcus aureus

The effects in vitro of tea tree oil (TTO) and plaunotol were examined by monitoring the growth of a standard strain of Staphylococcus aureus FDA 209P and of fourteen methicillin-susceptible strains of S. aureus (MSSA), together with twenty methicillin-resistant strains (MRSA). The minimum inhibitory concentrations (MIC) and the doses for 50% inhibition of growth (ID50) were determined by the micro-broth dilution (MD) method, and the broth dilution with shaking (BDS) method, respectively. The MIC of plaunotol for 50 and 90% of the MSSA and MRSA were assessed by the MD method, as 16 microg/ml and > or = 1,024 microg/ml, respectively. No antibacterial effects of TTO on MSSA and MRSA were detected by the MD method. The growth-inhibitory effects of TTO on S. aureus by the BDS method were examined, and it appeared that TTO was effective over a lower range of concentrations than previously reported. It seems that TTO is very effective in vitro against MSSA and MRSA at high concentrations but less effective below 40 microg/ml of TTO.     

Antibacterial and bactericidal activities of tea extracts and catechins against methicillin resistant Staphylococcus aureus]

We examined tea extract, (-) epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) for their antibacterial and bactericidal activities against methicillin resistant Staphylococcus aureus (MRSA) and food poisoning strains of S. aureus. Twenty percent tea extract (50 microliters), EGCg (63 micrograms) and TF3 (125 micrograms) added to one ml of culture medium each inhibited the growth of all strains of MRSA and food poisoning S. aureus tested. Tea extract showed also a bactericidal activity against MRSA even at the same concentration of as in ordinarily brewed tea. EGCg at a concentration of 250 micrograms/ml showed a bactericidal activity against MRSA but not against food poisoning S. aureus, but at 500 micrograms/ml reduced markedly the viable number within 48h. These results suggest that tea and catechin can be used as prophylactic agents against MRSA infection.     

Comparison of disk-diffusion method and PCR for detection of methicillin resistance in Staphylococcus aureus strains

The aim of the study was to compare the disk-diffusion (oxacillin 1 microg, cefoxitin 30 microg) method and PCR for detection of methicillin-resistance in S. aureus. The investigation were carried out on 120 S. aureus strains isolated from clinical materials of patients hospitalized in the University Hospital at the L. Rydygier Collegium Medicum in Bydgoszcz, University of Nicolaus Copernicus in Toruń. Of the 120 S. aureus strains tested, 60 (50%) were mecA-positive by PCR. Consistency of results between oxacillin disk-difussion method and PCR amounted 92.5% and cefoxitin disk-diffusion method and PCR--98.3%. The oxacillin disk-difussion method falsely identified 3 (2.5%) strains as MSSA (sensitivity 95.0%) and 4 strains as MRSA (specificity 93.3%) in comparison with PCR. The cefoxitin disk-diffusion method falsely identified 2 (1.6%) strains as MSSA (sensitivity 96.7%) and there were no false resistant results (specificity 100%). Our results showed that in disk-diffusion tests, cefoxitin is a better than oxacillin for the identification of MRSA.     

Characterisation of virulence genes in methicillin susceptible and resistant Staphylococcus aureus isolates from a paediatric population in a university hospital of Medellín, Colombia

Virulence and antibiotic resistance are significant determinants of the types of infections caused by Staphylococcus aureus and paediatric groups remain among the most commonly affected populations. The goal of this study was to characterise virulence genes of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains isolated from a paediatric population of a Colombian University Hospital during 2009. Sixty MSSA and MRSA isolates were obtained from paediatric patients between zero-14 years. We identified the genes encoding virulence factors, which included Panton-Valentine leucocidine (PVL), staphylococcal enterotoxins A-E, exfoliative toxins A and B and toxic shock syndrome toxin 1. Typing of the staphylococcal chromosome cassette mec (SCCmec) was performed in MRSA strains. The virulence genes were more diverse and frequent in MSSA than in MRSA isolates (83% vs. 73%). MRSA strains harboured SCCmec types IVc (60%), I (30%), IVa (7%) and V (3%). SCCmec type IVc isolates frequently carried the PVL encoding genes and harboured virulence determinants resembling susceptible strains while SCCmec type I isolates were often negative. PVL was not exclusive to skin and soft tissue infections. As previously suggested, these differences in the distribution of virulence factor genes may be due to the fitness cost associated with methicillin resistance.     

Staphylococcus aureus nosocomial infections: the role of a rapid and low-cost characterization for the establishment of a surveillance system

Continuous surveillance on resistance patterns and characterization of Staphylococcus aureus represent simple and low-cost techniques to understand and evaluate the effectiveness of infection control and antimicrobial prescribing measures. In this study we analyzed the antibiotic susceptibility and trends for S. aureus strains collected from bacteraemia cases in a five year period. Between 2004 and 2008 we noted a progressive decrease in the number of S. aureus isolates compared to all pathogens from clinical specimens and S. aureus bloodstream infections (BSI) reflected a similar trend. In particular we analyzed 185 isolates from blood cultures: 89 isolates were MSSA and 96 isolates were MRSA. Molecular SCCmec typing of these strains showed an absolute prevalence of types I and II, whereas five spa types from 96 isolates were obtained. Resistance pattern analysis allowed us to place MRSA strains into 12 antibiotypes and the major antibiotype was resistant to penicillin, gentamicin, erythromycin, clindamycin and ciprofloxacin. The predominant antibiotype among the MSSA isolates was resistant only to penicillin. In addition, 19.1% of MSSA are susceptible to all antibiotics tested. We also found a close association between antibiotyping 1 and genotyping t002/SCCmecI of MRSA strains, suggesting a nosocomial scenario dominated by a few particular clones.     

Characterization of cell membrane parameters of clinical isolates of Staphylococcus aureus with varied susceptibility to alpha-melanocyte stimulating hormone

Staphylococcus aureus (S. aureus), a major human pathogen of hospital and community acquired infections, is becoming resistant to almost all commercially available antibiotics. This has prompted development of antimicrobial peptides as therapeutic options. Alpha melanocyte stimulating hormone (α-MSH) is one such peptide known to possess antimicrobial properties. In the present study, we analyzed the antimicrobial activity of α-MSH against 75 clinical strains of S. aureus including both methicillin susceptible S. aureus (MSSA) and methicillin resistant S. aureus (MRSA) strains. Results of our previous study showed that membrane damage is the major mechanism of staphylocidal activity of α-MSH. In this context, we compared the various bacterial membrane parameters, viz., membrane fluidity, lipid composition, and surface charge of a few selected MSSA and MRSA strains that showed variable susceptibility to the melanocortin peptide. Our results showed that α-MSH killed both type of strains efficiently (≥70% killing in 84% clinical strains after exposure with 6μM of α-MSH for 1h). It was observed that compared to the α-MSH-susceptible strains, the α-MSH-non-susceptible strains had a different membrane order and phospholipid pattern. There was no consistent pattern of cell surface charge to distinguish α-MSH-susceptible strain from a non-susceptible strain. In conclusion, α-MSH possessed potential staphylocidal activity for both against MSSA and MRSA strains. S. aureus strains not susceptible to the peptide exhibited a rigid membrane and a higher amount of the cationic phospholipid as compared to the α-MSH-susceptible strains.     

烧伤病房患者创面金葡菌分布及耐药性分析

目的分析烧伤病房患者不同创面金葡菌的分布及耐药性,为临床合理选用抗菌药提供依据。方法对2006年1月至2013年12月间中国人民解放军第八五医院烧伤病房患者创面分离出金葡菌,采用K—B纸片扩散法进行药物敏感试验。分析金葡菌的耐药性,并对难愈性创面、非难愈性创面的耐甲氧西林金葡菌（MRSA）与甲氧西林敏感金葡菌（MSSA）的耐药性进行对比分析。结果分离出金葡菌112株,其中难愈性创面有70株MRSA和17株MSSA来自难愈性创面,16株MRSA和9株MSSA来自非难愈性创面。金葡菌对青霉素、红霉素、克林霉素的耐药率较高（分别为94．64％、81．25％和74．11％）,对复方新诺明、呋喃妥因的耐药率较低（分别为16．07％和1．79％）,对万古霉素、利奈唑烷的耐药率为0。MRSA的耐药率高于MSSA。来源于难愈性创面与非难愈性创面的MRSA仅在对利福平的耐药率上有明显差异,而来源于两创面的MSSA的耐药率无明显差异。结论创面金葡菌中MRSA的构成比高,难愈性创面MRSA耐药严重,应积极防控创面MRSA感染和扩散。     

Sensitivity of methicillin-resistant Staphylococcus aureus strains to some antibiotics, antiseptics and disinfectants

The effects of antibiotics, antiseptics and disinfectants against some methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) Staphylococcus aureus strains have been studied. The MRSA and MSSA strains were equally sensitive to phenols, esters of para(4)-hydroxybenzoic acid and chlorhexidine but MRSA strains were slightly more resistant to quaternary ammonium compounds and considerably more so to dibromopropamidine isothionate. Some MRSA strains were also resistant to phenylmercuric nitrate (but not another organomercurial, thiomersal), mercuric chloride and cadmium chloride. All MRSA strains produced beta-lactamase. Strains from the Royal Free Hospital, London were highly resistant to beta-lactam antibiotics, erythromycin, trimethoprim and tetracyclines but were sensitive to other antibiotics. One strain from the University Hospital of Wales, Cardiff was resistant to gentamicin but sensitive to tetracycline and trimethoprim.     

耐甲氧西林金黄色葡萄球菌及其肠毒素的检测和耐药性分析

目的评价乳胶结合试验检测耐甲氧西林金黄色葡萄球菌(MRSA)及其肠毒素(SE),并进行耐药性分析.方法收集130株金黄色葡萄球菌临床分离株,通过药敏试验将其分为耐甲氧西林金黄色葡萄球菌和甲氧西林敏感金黄色葡萄球菌(MSSA),用反向间接血凝试验(RPHA)检测金黄色葡萄球菌肠毒素.结果67株MR-SA产肠毒素,19株MSSA产肠毒素,MRSA产肠毒素率为100%,MSSA产肠毒素率为30%.结论实验室应重视金黄色葡萄球菌肠毒素的检测.     

Sensitivity of methicillin-resistant Staphylococcus aureus strains to some antibiotics, antiseptics and disinfectants

The effects of antibiotics, antiseptics and disinfectants against some methicillin resistant (MRSA) and methicillin-sensitive (MSSA) Staphylococcus aureus strains have been studied. The MRSA and MSSA strains were equally sensitive to phenols, esters of para(4)-hydroxybenzoit acid and chlorhexidine but MRSA strains were slightly more resistant to quaternary ammonium compounds and considerably more so to dibromopropamidine isothionate. Some MRSA strains were also resistant to phenylmercuric nitrate (but not another organomercurial, thiomersal), mercuric chloride and cadmium chloride. All MRSA strains produced β-lactamase. Strains from the Royal Free Hospital, London were highly resistant to β-lactam antibiotics, erythromycin, trimethoprim and tetracyctines but were sensitive to other antibiotics. One strain from the University Hospital of Wales, Cardiff was resistant to gentamicin but sensitive to tetracycline and trimethoprim.     

Comparison of methods for the detection of methicillin resistance in Staphylococcus aureus isolates from food products

AIMS: To compare several methods for detection of methicillin resistance in Staphylococcus aureus isolates from food. METHODS AND RESULTS: Two hundred S. aureus isolates from food of animal origin were screened for methicillin resistance by a PCR assay specific for the mecA gene, an oxacillin agar screen test and a cefoxitin disk diffusion test. Six out of 200 strains (3%) were found to be methicillin-resistant Staphylococcus aureus (MRSA) by PCR. The oxacillin agar screen test detected only one of the MRSA isolates (sensitivity of 16.7%) and mischaracterized three additional strains as MRSA (specificity of 98.45%). None of the MRSA strains was detected by the cefoxitin test (sensitivity of 0%), while 15 methicillin-susceptible S. aureus (MSSA) strains were misclassified as resistant (specificity of 92.3%). Fifteen MSSA strains displayed a beta-lactamase hyperproducer-like phenotype. The six MRSA (mecA-positive) strains resembled the characteristics of heteroresistant strains. CONCLUSIONS: As MRSA of animal origin may display atypical phenotypes, PCR appears to be more reliable for detection of methicillin resistance in animal strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The study stresses the need for implementing the methods of screening S. aureus from food of animal origin for methicillin resistance.     

Panton-Valentine leukocidin is not the primary determinant of outcome for Staphylococcus aureus skin infections: evaluation from the CANVAS studies

The impact of Panton-Valentine leukocidin (PVL) on the severity of complicated skin and skin structure infections (cSSSI) caused by Staphylococcus aureus is controversial. We evaluated potential associations between clinical outcome and PVL presence in both methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) isolates from patients enrolled in two large, multinational phase three clinical trials assessing ceftaroline fosamil for the treatment of cSSSI (the CANVAS 1 and 2 programs). Isolates from all microbiologically evaluable patients with monomicrobial MRSA or MSSA infections (n?=?473) were genotyped by PCR for pvl and underwent pulsed-field gel electrophoresis (PFGE). Genes encoding pvl were present in 266/473 (56.2%) isolates. Infections caused by pvl-positive S. aureus were associated with younger patient age, North American acquisition, and presence of major abscesses (P<0.001 for each). Cure rates of patients infected with pvl-positive and pvl-negative S. aureus were similar overall (93.6% versus 92.8%; P?=?0.72), and within MRSA-infected (94.5% vs. 93.1%; P?=?0.67) and MSSA-infected patients (92.2% vs. 92.7%; P?=?1.00). This finding persisted after adjustment for multiple patient characteristics. Outcomes were also similar when USA300 PVL+ and non-USA300 PVL+ infections were compared. The results of this contemporary, international study suggest that pvl presence was not the primary determinant of outcome in patients with cSSSI due to either MRSA or MSSA.     

深圳市人民医院近五年临床分离金黄色葡萄球菌的 分布及耐药性分析

目的分析医院感染患者金黄色葡萄球菌的临床分布特征及耐药性变化,为临床治疗金黄色葡萄球菌感染提供依据。方法回顾性分析2012年1月至2016年12月我院从临床各类标本中分离获得的1 141株金黄色葡萄球菌,统计其在各类标本和病区中的分布特点,并用K-B法测定该菌对常用抗菌药物的敏感性。结果 5年中共分离出1 141株金黄色葡萄球菌,标本来源构成比最多的是伤口分泌物(43.3%)、呼吸道标本(24.0%)和血液标本(10.2%)。耐甲氧西林金黄色葡萄球菌(MRSA)共有339株,占29.7%。各年MRSA的检出数依次为53株(31.9%)、51株(26.0%)、82株(35.2%)、81株(30.3%)和72株(26.0%)。MRSA主要分离自神经外科(13.8%)、呼吸监护室(10.6%)、重症监护室(8.8%)和骨科(7.7%)。MRSA对抗菌药物的耐药性普遍高于MSSA,二者比较差异有统计学意义(P0.05)。未发现对万古霉素、利奈唑胺、替考拉宁耐药的金黄色葡萄球菌。结论 MRSA感染多发生于长期使用抗菌药物,有皮肤软组织伤口及侵入性操作的科室及患者。MRSA具有多重耐药性,应严格掌握抗菌药物的使用适应证;同时临床治疗应根据药物敏感性报告针对性地合理用药,以便及时有效地控制感染并防止耐药菌株的扩散。     

Detection and identification of methicillin resistant and sensitive strains of Staphylococcus aureus using tandem measurements

Discrimination of methicillin resistant (MRSA) and sensitive (MSSA) strains of Staphylococcus aureus, was achieved by the specially selected lytic bacteriophage with a wide host range of S. aureus strains and a penicillin-binding protein (PBP 2a) specific antibody. A quartz crystal microbalance with dissipation monitoring (QCM-D) was employed to analyze bacteria-phage interactions. The lytic phages were transformed into phage spheroids by exposure to water-chloroform interface. Phage spheroid monolayers were transferred onto QCM-D sensors by Langmuir-Blodgett (LB) technique. Biosensors were tested in the flow mode with bacterial water suspensions, while collecting frequency and energy dissipation changes. Bacteria-spheroid interactions resulted in decreased resonance frequency and an increase in dissipation energy for both MRSA and MSSA strains. Following the bacterial binding, these sensors were further exposed to a flow of the penicillin-binding protein (PBP 2a) specific antibody conjugated latex beads. Sensors tested with MRSA responded to PBP 2a antibody beads; while sensors examined with MSSA gave no response. This experimental difference establishes an unambiguous discrimination between methicillin resistant and sensitive S. aureus strains. Both free and immobilized bacteriophages strongly inhibit bacterial growth on solid/air interfaces and in water suspensions. After lytic phages are transformed into spheroids, they retain their strong lytic activity and demonstrate high bacterial capture efficiency. The phage and phage spheroids can be used for screening and disinfection of antibiotic resistant bacteria. Other applications may include use on biosensors, bacteriophage therapy, and antimicrobial surfaces.     

Identification and discrimination of Staphylococcus aureus strains using matrix-assisted laser desorption/ionization-time of flight mass spectrometry

Staphylococcus aureus is an important human pathogen frequently resistant to a wide range of antibiotics. Methicillin-resistant S. aureus (MRSA) strains are common nosocomial pathogens that pose a world-wide problem. Rapid and accurate discrimination between methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus is essential for appropriate therapeutic management and timely intervention for infection control. We report here the application of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) for monitoring the bacterial fingerprints expressed by two well characterized S. aureus strains ATCC 29213 (MSSA) and ATCC 43330 (MRSA). Consistent strain-specific data were obtained from subcultures analyzed over a period of three months as well as after changing the growth media from Mueller-Hinton to blood agar indicating the reliability of the method. The bacterial fingerprints of these two strains were compared to independent clinical isolates of S. aureus. A uniform signature profile for MRSA could not be identified. However, the bacterial fingerprints obtained proved to be specific for any given strain. This study demonstrates that MALDI-TOF MS is a powerful method for rapid identification of clonal strains of S. aureus, which might be useful for tracking nosocomial outbreaks of MRSA and for epidemiologic studies of infections diseases in general.     

猪源致病性金黄色葡萄球菌的分离鉴定及其耐药性分析

目的鉴定引起猪渗出性皮炎的病原,并分析猪源致病性金黄色葡萄球菌的耐药性,为临床用药提供依据。方法采集患渗出性皮炎的仔猪标本进行细菌分离培养,联合应用形态学检查、生理生化试验和PCR方法鉴定分离菌株,并进行致病性和药物敏感性试验。结果先后从病猪标本中分离鉴定获得PSA1、PSA2、PSA3和PSA4四株金黄色葡萄球菌,其中PSA1和PSA3分离株的致病性较强。药敏试验结果显示PSA1、PSA2和PSA3分离株为MRSA菌株,PSA4分离株为MSSA菌株。MRSA菌株对14种抗菌药物均呈现不同程度的耐药,尤其是对青霉素、链霉素、四环素、强力霉素、环丙沙星和氧氟沙星等6种抗菌药物的耐药率达100%。所有分离株对万古霉素与替考拉宁均敏感。结论合肥地区猪渗出性表皮炎的病原为金黄色葡萄球菌。猪源致病性金黄色葡萄球菌合肥分离株具有多重耐药性,治疗猪渗出性皮炎应建立在体外药敏试验的基础上,有针对性选择抗菌药物。     

Reduced susceptibility to triclosan in methicillin-resistant Staphylococcus aureus

Susceptibility to triclosan in Staphylococcus aureus was determined. The study was carried out on 200 strains, including 100 resistant (MRSA) and 100 susceptibile (MSSA) to methicillin. The examined strains were isolated from varied clinical samples and patients in 18 medical centers, in majority from hospitals in the region of Gdansk. The susceptibility was estimated by the MIC (minimal inhibitory concentration) using dilution test in Mueller-Hinton agar. The antimicrobial resistance patterns were determined, including resistance to methicillin and mupirocin. The most of MRSA strains (62%) demonstrated reduced susceptibility to triclosan (MIC 2mg/L), while 93% of MSSA strains were highly sensitive to this antibacterial agent (MIC 0,031mg/L). The majority (66,1%) of MRSA strains with reduced susceptibility to triclosan demonstrated the same antimicrobial resistance pattern. Reduced susceptibility to triclosan was observed in 8 from 9 high - level mupirocin resistant strains, but the most of MRSA strains with reduced triclosan susceptibility (91,5%) were found among fusidic acid resistant strains.     

皮肤软组织感染病原菌分布及耐药性分析

目的 调查皮肤软组织感染病原菌的种类及耐药性,为临床合理使用抗菌药物提供科学依据.方法 利用WHONET 5.6对2009年1月至2011年12月皮肤软组织感染患者脓液或分泌物细菌培养及药敏试验结果进行回顾性分析.结果 共分离菌株444株,金黄色葡萄球菌(SAU)分离率居第1位,171株占38.5％;表皮葡萄球菌居第2位,54株占12.2％;铜绿假单胞菌第3位,43株占9.7％;头孢哌酮/舒巴坦、哌拉西林/他唑巴坦、阿米卡星、亚胺培南和美罗培南对革兰阴性杆菌有较好的抗菌活性(耐药率≤3.3％);金黄色葡萄球菌对青霉素和红霉素的耐药率为93.6％和65.0％,对呋喃妥因、利奈唑胺、利福平、莫西沙星和左旋氧氟沙星耐药率为0％、0％、1.4％、2.2％和9.3％,未检出万古霉素耐药株;耐甲氧西林金黄色葡萄球菌(MRSA)检出率25.7％ (44/171);MRSA和甲氧西林敏感金黄色葡萄球菌(MSSA)对氨苄西林/舒巴坦、利福平、莫西沙星三种药物的敏感性差异有统计学意义.结论 引起皮肤软组织感染病原菌以阳性球菌尤其是金黄色葡萄球菌为主,临床上应尽量根据药敏试验结果选用抗生素,合理用药.     

Antibacterial potential of Malaysian ethnomedicinal plants against methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA)

This study aimed to evaluate the antibacterial activities of 61 plant extracts from 49 Malaysian ethnomedicinal plants and to investigate the interaction of the active plant extracts in combination with synthetic antibiotics against the MSSA and MRSA strains. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the plant extracts were determined using a microdilution method against MSSA and MRSA strains. The interaction between active plant extracts and the antibiotics was assessed using the checkerboard method. The total fractional inhibitory concentration (∑FIC) indices from the combination were calculated to determine the nature of the interaction. Out of the 61 plant extracts tested against the MSSA strain, 7 plant extracts (̴ 11%) showed MIC values of less than 200 μg/mL, 17 extracts (̴ 28%) showed MIC between 200 and 800 µg/mL and seed extracts of Areca catechu showed MBC values of 400 μg/mL. The seed extract of A. catechu showed MIC and MBC of 400 μg/mL against the MRSA strains while leaf extract of Cocos nucifera showed MIC of 400 μg/mL against MRSA NCTC 12493. When the active plant extracts (MIC ≤ 200 µg/mL for MSSA, and ≤ 400 µg/mL for MRSA) were tested in combination with vancomycin and ciprofloxacin, they showed no interaction against both MSSA and MRSA with ∑FIC between 1.06 and 2.03. These findings provide a preliminary overview of the anti-MSSA and anti-MRSA properties of Malaysian ethnobotanical plants to combat Staphylococcal infections. Further research is needed to establish an antibacterial profile of the tested plant extracts.     

Occurrence of macrolide-lincosamide-streptogramin B resistant isolates of Staphylococcus aureus in clinical specimens in 2003-2004

The aim of the study was the analysis of frequency of macrolide-lincosamide-streptogramin B (MLS(B)) resistance among MSSA (n=1682) and MRSA (n=272) strains which were isolated in 2002-2004 from various clinical materials from patients hospitalized in the University Hospital at the L. Rydygier Collegium Medicum in Bydgoszcz, University of Nicolaus Copernicus in Toruń. Susceptibility testing and examination of methicillin-resistant strains were performed by the disc diffusion techniques according to recommendation of NCCLS. Resistance to the MLS(B) antimicrobials agents was higher among MRSA compared to MSSA isolates. The MLS, constitutive phenotype was more prevalent than the MLS(B) inducible phenotype among investigated MRSA (65.4%) and MSSA (7.6%) isolates. Inducible resistance had only 2.5% of the MSSA and 2.6% of the MRSA strains. Moreover in 2004 there were found increasing frequency of inducible MLS(B) resistance from 1.1% to 5.7% and decreasing frequency of constitutive MLS(B) resistance from 9.2% to 4.7% among MSSA strains, in comparison to 2003. The investigated MSSA MLS(B)-, MLS(B)- and MRSAMLS(B)+, MLS(B)- strains were the most frequently isolated from pus (adequately 5.2%, 28.8% and 30.5%, 10.7%) and also from nosopharynx swabs (1.7% MSSA MLS(B)+ and 22.9% MSSA MLS(B)-) and biomaterials (15,1% MRSA MLS(B)+ and 9.6% MRSA MLS(B)-). They mainly came from patients of the outpatient clinic (2,4% MSSA MLS(B)+ and 19.9% MSSA MLS(B)-) and patients treated at the neurosurgical ward (20.6% MRSA MLS(B)+ and 12.1% MRSA MLS(B)-).