Methicillin-resistant Staphylococcus aureus from infected skin lesions present several virulence genes and are associated with the CC30 in Brazilian children with atopic dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease and colonization by Staphylococcus aureus may affect up to 100% of these patients. Virulent and resistant isolates can worsen AD patient clinical condition and jeopardize the treatment. We aimed to detect virulence genes and to evaluate the biofilm production of S. aureus isolates from infected skin lesions of children with AD. Methicillin resistance was detected by phenotypic and molecular tests and the virulence genes were detected by PCR. Biofilm formation was assessed by bacterial growing on microtiter plates and later stained with safranin. Genotyping was performed by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing. Among 106 AD patients, 55 (51.8%) had developed S. aureus cutaneous infections and 23 (41.6%) were methicillin-resistant (MRSA). All 55 isolates carried the fnbA, hla, icaA, sasG, and seu genes, and more than 70% presented cna, eap, ebpS, hlg, and pvl genes. Clonal complex (CC) 30 was the main lineage found (34.5%), especially among MRSA isolates (52.2%). The egc cluster and the bbp gene were significantly the most frequent in MRSA isolates and in USA1100/ST30/CC30 lineage. Most of the isolates (74.5%) were non-biofilm producers and many of them only started to produce it in the presence of fibrinogen. There was no significant association between S. aureus isolates features and the AD severity. This study demonstrated a high frequency of CC30 MRSA isolates presenting several virulence genes in infected skin lesions of AD children in Brazil, that may influence the severity of the disease and the treatments required.

Staphylococcus aureus nasal isolates may have the same genetic profile in atopic dermatitis paediatric patients and their close contacts.

Atopic dermatitis (AD) is a chronic skin disease that affects up to 20 % of the paediatric population worldwide. Staphylococcus aureus colonizes anterior nares and can be transmitted in the home environment, aggravating AD. This study aimed to detect S. aureus from nares of AD patients and their family contacts, as well as to evaluate the antimicrobial resistance, virulence and clonality of these isolates. Among the 48 family groups investigated, 30 groups were selected, as both the child and his/her respective contact had methicillin-sensitive S. aureus (MSSA) (24 cases; 54 MSSA isolates) or methicillin-resistant S. aureus (MRSA) isolates (6 cases; 13 MRSA isolates). All MRSA isolates carried SCCmec IV. S. aureus carrying PVL genes were detected in 60 % of patients. Pulsed-field gel electrophoresis (PFGE) analysis was performed for 31 isolates from 15 family groups: all 6 with MRSA and 9 with MSSA isolates. Similar genotypic profiles between isolates from patients and their family contacts were noted in 10 (66.6 %) family groups, 5 (83.3 %) of the MRSA family groups and 5 (55.5 %) of the MSSA family groups, indicating that the pathogen was transmitted through family contacts.

Methicillin-resistant Staphylococcus epidermidis isolates with reduced vancomycin susceptibility from bloodstream infections in a neonatal intensive care unit.

Introduction. Vancomycin has become the first-line therapy for most infections caused by methicillin-resistant staphylococci.Aim. To evaluate the vancomycin MIC, staphylococcal cassette chromosome mec (SCCmec) types and clonality of coagulase-negative staphylococci (CoNS) isolates recovered from neonates with true primary bloodstream infections (BSI).Methodology. CoNS isolates were prospectively recovered from blood cultures of non-repetitive patients admitted to a neonatal intensive care unit (NICU) in a tertiary-care hospital during a 3-year period. BSI was defined based on established criteria. Micro-organisms were identified phenotypically and by PCR. MIC-values for vancomycin and oxacillin were determined by broth dilution method and E-test. The SCCmec type conferring methicillin resistance was determined by multiplex PCR. The heterogeneous vancomycin (hV) resistance phenotype was screened on brain heart infusion agar containing 4 µg ml-1 of vancomycin. The clonality was investigated by PFGE.Results. Seventy-four CoNS isolates were recovered from blood cultures of neonates during the study period but only 40 (54 %) were associated with true primary BSI. Nine (22.5%) babies died. Staphylococcus epidermidis was the most prevalent species (95 %; 38/40). All S. epidermidis isolates were methicillin-resistant (MR). SCCmec type IV was predominant (55.3 %; 21/38). Most (80.0 %; 32/38) isolates exhibited vancomycin MIC-values of 2-4 µg ml-1 not associated with the SCCmec type or clonality. Sixteen (42.1%) isolates displayed hV resistance. All babies who died were harbouring MR-S. epidermidis exhibiting vancomycin MICs of 2-4 µg ml-1.Conclusion. The findings of this study demonstrated that blood invasive MR-S. epidermidis isolates recovered at NICU tend to show decreased vancomycin susceptibility making therapy of those fragile patients difficult.

Effect of Coffea canephora aqueous extract on microbial counts in ex vivo oral biofilms: a case study.

In the present study, the ex vivo antimicrobial effect of brewed coffee was tested on oral biofilms. For this, unsweetened and sweetened (10 % sucrose) brewed light-roasted Coffea canephora at 20 % was used in biofilms formed by non-stimulated saliva from three volunteers. After 30 min contact with unsweetened and sweetened brews, the average microorganism count in the biofilms reduced by 15.2 % and 12.4 %, respectively, with no statistical difference among them. We also observed a drop of microorganisms in the biofilms after treatment with sucrose solution at 5 % compared to control (saline) and to sucrose at 1 % and 3 %. In conclusion, Coffea canephora extract reduces the microbial count in oral biofilm, and our data suggest that sucrose concentration in coffee brew can influence its antimicrobial property against the referred biofilm.

Interpretive criteria to differentiate low- and high-level mupirocin resistance in Staphylococcus aureus.

Meticillin-resistant Staphylococcus aureus isolates were classified into three mupirocin susceptibility groups by the disc diffusion method using 5 and 200 microg mupirocin discs. The zone diameter observed for a 5 microg disc distinguished Mup(S) from the resistant strains (either Mup(RL) or Mup(RH)). On the other hand, a 200 microg disc distinguished the high-resistance Mup(RH) strains from the other two (Mup(S) or Mup(RL)). Thus, the concomitant use of 5 and 200 microg mupirocin discs allowed the clear distinction among the three mupirocin susceptibility groups, Mup(S), Mup(RL) or Mup(RH).

Improvement of mupirocin E-test for susceptibility testing of Staphylococcus aureus.

Interpretation of the mupirocin E-test for low-level mupirocin-resistant Staphylococcus aureus strains has been improved by adding the indicator dye tetrazolium. E-tests were compared with agar dilution methods for assessing mupirocin susceptibility. MICs obtained by the agar dilution method and E-tests showed 89.3% agreement within 2 log(2) dilution criteria. The agreement between MICs increased to 100% in the 1 log(2) dilution definition when the indicator dye tetrazolium was added to the E-test. The use of the E-test with tetrazolium reduction is more accurate for determining mupirocin MICs for S. aureus strains.

Susceptibility of Brazilian staphylococcal strains to glycopeptides evaluated by different testing methods.

Reports of staphylococci with reduced susceptibility to glycopeptides are cause for concern. This study evaluated the susceptibility of 84 staphylococci clinical isolates to glycopeptides by the disk diffusion, agar dilution, E-test, and BHIA screening methods. Vancomycin agar dilution showed all strains presented minimum inhibitory concentration (MIC) ranging from 0.5 to 2 microg/ml, and the E-test showed similar results. Teicoplanin agar dilution test showed MICs ranging from < or = 0.5 to 2 microg/ml for Staphylococcus aureus and MICs ranging from <0.25 to 32 microg/ml for coagulase-negative Staphylococcus (CNS). Ten CNS isolates presented MICs ranging from 8 to 32 microg/ml for agar dilution and/or E-test. All the staphylococci were susceptible to vancomycin by the disk diffusion test (DDT), but two CNS isolates presented intermediate resistance to teicoplanin by the DDT and MICs of susceptibility, with two other CNS strains, teicoplanin-susceptible by the DDT, presented MICs of intermediate resistance. On the vancomycin-containing agar, 20 CNS isolates were able to grow, but no S. aureus strain. All these isolates showed MICs to teicoplanin (4-32 microg/ml) higher than those isolates that did not grow on the agar screen plate. PFGE of chromosomal SmaI digests showed a wide diversity of these CNS strains, without any predominance of a single PFGE pattern.