Characteristics of the extended collection of representative MRSA strains.

<p>Abbreviations: neg., negative; pos., positive; WT, wild-type; ND, not determined.</p><p>Notes:</p>a)<p>Clonal types as defined by MLST sequence type (ST) and SCC<i>mec</i> type.</p>b)<p>neg. – negative (due to IS<i>1272</i> or IS<i>431</i> insertions); WT – wild-type sequence (N315); * - mutated non-functional <i>mecI</i>.</p>c)<p>IS::Δ<i>mecR1</i> – <i>mecR1</i> with no C-terminal sensor domain (due to IS<i>1272</i> or IS431 insertions).</p>d)<p>The production of β-lactamase was tested for induced and no induced cultures (see text for details). All strains positive for β-lactamase were inducible. Strains negative for the nitrocefin assay were tested for the presence of <i>blaZ</i>, blaI, and <i>bla</i>R1 by PCR.</p>e)<p>MIC as determined by E-test strips.</p>f)<p>Parental strains transformed with a high copy number plasmid containing the wild-type <i>mecI</i> coding region (pGC2-<i>mecI</i>^WT).</p

Electrophoretic mobility shift assay of relative MecI and BlaI affinities for the <i>mecA</i> promoter sequence.

<p>Binding reaction was performed with a labeled 200 bp DNA fragment encompassing the <i>mecA</i> promoter mixed with increasing amounts of purified MecI (panel A) and BlaI (panel B). Lanes are as follows: lane 1 – no protein (control); lane 2 – 0,001 µg; lane 3 – 0,01 µg; lane 4 – 0,05 µg; lane 5 – 0,1 µg; lane 6 – 0,25 µg; lane 7 – 0,5 µg; lane 8 – 1 µg; lane 9 – 0,1 ug of protein with a 125 molar excess of unlabelled DNA (specific competition).</p

Northern blot analysis of the <i>mecA</i> induction profile in three prototype MRSA strains.

<p>Induction of <i>mecA</i> transcription for three prototype strains upon exposure to oxacillin at 0′, 5′, 15′, 30′, and 60′. Strain relevant characteristics are as follows: strain PER34 - SCC<i>mec</i> type I, <i>mecI</i> negative, Δ<i>mecR1</i>; strain HU25 - SCC<i>mec</i> type III, <i>mecI</i>*, <i>mecR1</i>^WT; strain N315 - SCC<i>mec</i> type II, <i>mecI</i>^WT<i>mecR1</i>^WT. The three strains are β-lactamase positive.</p

Population analysis profiles of representative parental strains and recombinant strains.

<p>Panel A – strain COL and its recombinants strains COL+pGC2-<i>mecI</i>^WT, COL+pGC2-<i>mecI</i>*, and COL+pGC2-<i>mecImecR1</i> grown overnight with and without oxacillin before plating onto TSA plates. Panel B – strain PER34 (SCC<i>mec</i> type I) and PER34+pGC2-<i>mecI</i>^WT. Panel C – strain BK2464 (SCC<i>mec</i> type II) and BK2464+pGC2-<i>mecI</i>^WT. Panel D – strain HU25 (SCC<i>mec</i> type III) and HU25+pGC2-<i>mecI</i>^WT.</p

Characteristics of the prototype MRSA strains used in this study.

<p>Abbreviations: neg., negative; pos., positive; WT, wild-type.</p><p>Notes:</p>a)<p>Clonal types as defined by MLST sequence type (ST) and SCC<i>mec</i> type.</p>b)<p>neg. – negative (due to IS<i>1272</i> insertion); WT – wild-type sequence (N315);</p><p>*- mutated non-functional <i>mecI</i> at Gln₆₈ (CAA→TAA);</p>c)<p>IS::Δ<i>mecR1</i> – <i>mecR1</i> with no C-terminal sensor domain (due to IS<i>1272</i> insertion); Δ<i>mecR1</i> – 160 bp deletion in the C-terminal inducer domain.</p>d)<p>The production of β-lactamase was assayed in induced and no induced cultures (see text for details). All strains positive for β-lactamase were inducible.</p>e)<p>MIC as determined by E-test strips.</p>f)<p>Parental strains transformed with a high copy number plasmid containing the wild-type <i>mecI</i> coding region (pGC2-<i>mecI</i>^WT).</p

Identification of <i>Staphylococcus aureus</i>, including MRSA, among nursing students.

<p>Identification of <i>Staphylococcus aureus</i>, including MRSA, among nursing students.</p

Clonal lineages, antimicrobial resistance and virulence of MRSA isolates recovered from piglets, farm workers and households in the two independent farms, Farm A and Farm B.

<p>Clonal lineages, antimicrobial resistance and virulence of MRSA isolates recovered from piglets, farm workers and households in the two independent farms, Farm A and Farm B.</p

Schematic representation of the interpersonal direct contact between individuals and between individuals and livestock, associated to the distribution of the different MRSA lineages.

<p>Schematic representation of the interpersonal direct contact between individuals and between individuals and livestock, associated to the distribution of the different MRSA lineages.</p

Characteristics of methicillin-susceptible <i>Staphylococcus aureus</i> recovered from nursing students.

<p>Characteristics of methicillin-susceptible <i>Staphylococcus aureus</i> recovered from nursing students.</p

Prevalence of serotypes 1, 5, and 7F over time.

<p>Prevalence of serotypes 1, 5, and 7F over time.</p