Staphylococcus aureus nasal carriage is a well-defined risk factor of infection with this bacterium. The increased risk of S. aureus infection in nasal carriers is supported by the fact that the strains isolated from both colonization and infection sites are indistinguishable in most of the cases. Persistent nasal carriage seems to be associated with an increased risk of infection and this status could be defined now in clinical routine by using one or two quantitative nasal samples. There is evidence for supporting the detection of nasal carriage of S. aureus in patients undergoing cardiac surgery and in those undergoing hemodialysis in order to implement decolonization measures. More studies are needed to determine which carriers have the highest risk of infection and why decolonization strategies failed to reduce S. aureus infection in some other groups of patients.

Objective: Staphylococcus aureus dominates the skin microbiota in patients with atopic dermatitis (AD), with bacterial loads correlating with disease severity. The aim of this exploratory study was to investigate the effect of a cosmetic lotion containing heat-treated Lactobacillus johnsonii NCC 533 (HT La1) on S. aureus colonization in AD patients. Methods: This open-label, multicenter study was performed in AD patients in Germany. First, detection of S. aureus was performed in all patients using the swab or scrub-wash method of sampling, followed by quantitative culture or quantitative polymerase chain reaction. Repeatability and reproducibility of all method combinations were evaluated to select the best combination of sampling and quantification. Second, a lotion containing HT La1 was applied to lesional skin twice daily for 3 weeks. Scoring using local objective SCORing Atopic Dermatitis (SCORAD), measurement of S. aureus load, and lesional microbiome analysis were performed before and after the 3-week treatment period. Results: Thirty-one patients with AD were included in the study. All sampling and quantification methods were found to be robust, reproducible, and repeatable for assessing S. aureus load. For simplicity, a combination of swab and quantitative polymerase chain reaction was chosen to assess the efficacy of HT La1. Following application of a lotion containing HT La1 to AD lesions for 3 weeks, a reduction in S. aureus load was observed in patients, which correlated with a decrease in local objective SCORAD. Interestingly, high baseline skin concentrations of S. aureus were associated with good responses to the lotion. Conclusion: This study demonstrated that the application of a lotion containing HT La1 to the lesional skin of patients with AD for 3 weeks controlled S. aureus colonization and was associated with local clinical improvement (SCORAD). These findings support further development of topical treatments containing heat-treated nonreplicating beneficial bacteria for patients with AD.

The molecular diagnosis of respiratory infection can be performed using different commercial multiplex-based PCR kits whose performances have been previously compared individually to those of conventional techniques. This study compared the practicability and the diagnostic performances of six CE-marked kits available in 2011 on the French market, including 2 detecting viruses and atypical bacteria (from Pathofinder and Seegene companies) and 4 detecting only viruses (from Abbott, Genomica, Qiagen and Seegene companies). The respective sensitivity, specificity, accuracy and agreement of each multiplex technique were calculated by comparison to commercial duplex PCR tests (Argene/bioMérieux) used as gold standard. Eighty-eight respiratory specimens with no pathogen (n = 11), single infections (n = 33) or co-infections (n = 44) were selected to cover 9 viruses or groups of viruses and 3 atypical bacteria. All samples were extracted using the NUCLISENS® easyMAG™ instrument (bioMérieux). The overall sensitivity ranged from 56.25% to 91.67% for viruses and was below 50% with both tests for bacteria. The overall specificity was excellent (>94% for all pathogens). For each tested kit, the overall agreement with the reference test was strong for viruses (kappa test >0.60) and moderate for bacteria. After the extraction step, the hands-on time varied from 50 min to 2h30 and the complete results were available in 2h30 to 9 h. The spectrum of tested agents and the technology used to reveal the PCR products as well as the laboratory organization are determinant for the selection of a kit.

Introduction: Recent data highlight the importance of screening more than one site for improving the detection of S. aureus colonization. Intestinal carriage is frequently under-investigated and its clinical impact ought to be defined a better way. Areas covered: This review and meta-analysis provide an updated overview of prevalence, characteristics and clinical significance of S. aureus intestinal carriage in different populations, both for methicillin-susceptible and -resistant S. aureus strains. Expert commentary: Intestinal S. aureus carriage is documented with higher prevalence in children and in patients with S. aureus skin and soft tissue infections. This site of colonization was shown to be associated with a high risk of dissemination in the environment and with S. aureus infection. Intestinal carriage is frequently retrieved in nasal carriers, reflecting probably an association with a high bacterial load. Exclusive intestinal carriage present in one third of intestinal carriers can be associated with infection. Comparative genotyping analysis of different strains from nasal and extra-nasal sites of carriage, including the intestinal ones, in the same individuals, would allow a better comprehension of the pathophysiology of S. aureus endogenous infection. It could also permit to improve the prevention of these infections by decolonization of sites implicated in infection genesis.

The vestibulum nasi is considered the main site of Staphylococcus aureus colonization in humans (for a recent review see ref. [ 1 x 1 Wertheim, HFL, Melles, DC, Vos, MC et al. The role of nasal carriage in Staphylococcus aureus infections. Lancet Infect Dis. 2005; 5: 751–762 Abstract | Full Text | Full Text PDF | PubMed | Scopus (1112) | Google Scholar See all References 1 ]). Previous studies identified three patterns including persistent, intermittent and non-carrier states in approximately 20%, 30% and 50% of the whole population, respectively [ 1 x 1 Wertheim, HFL, Melles, DC, Vos, MC et al. The role of nasal carriage in Staphylococcus aureus infections. Lancet Infect Dis. 2005; 5: 751–762 Abstract | Full Text | Full Text PDF | PubMed | Scopus (1112) | Google Scholar See all References 1 ]. Persistent nasal carriers of S. aureus can be distinguished from intermittent carriers by a lower exchange rate of S. aureus strains or clones in repeated cultures [ 2 x 2 Hamdan-Partida, A, Sainz-Espuñes, T, and Bustos-Martínez, J. Characterization and persistence of Staphylococcus aureus strains isolated from the anterior nares and throats of healthy carriers in a Mexican community. J Clin Microbiol. 2010; 48: 1701–1705 Crossref | PubMed | Scopus (46) | Google Scholar See all References , 3 x 3 Eriksen, NH, Espersen, F, Rosdahl, VT, and Jensen, K. Carriage of Staphylococcus aureus among 104 healthy persons during a 19-month period. Epidemiol Infect. 1995; 115: 51–60 Crossref | PubMed | Scopus (127) | Google Scholar See all References , 4 x 4 Vandenbergh, MFQ and Verbrugh, HA. Carriage of Staphylococcus aureus: epidemiology and clinical relevance. J Lab Clin Med. 1999; 133: 525–534 Abstract | Full Text | Full Text PDF | PubMed | Scopus (59) | Google Scholar See all References ] and by a higher mean number of CFU of S. aureus in the nose [ 1 x 1 Wertheim, HFL, Melles, DC, Vos, MC et al. The role of nasal carriage in Staphylococcus aureus infections. Lancet Infect Dis. 2005; 5: 751–762 Abstract | Full Text | Full Text PDF | PubMed | Scopus (1112) | Google Scholar See all References , 4 x 4 Vandenbergh, MFQ and Verbrugh, HA. Carriage of Staphylococcus aureus: epidemiology and clinical relevance. J Lab Clin Med. 1999; 133: 525–534 Abstract | Full Text | Full Text PDF | PubMed | Scopus (59) | Google Scholar See all References ].