Corrigendum: Cross-Talk between Staphylococcus aureus and Other Staphylococcal Species via the agr Quorum Sensing System

[This corrects the article on p. 1733 in vol. 7, PMID: 27877157.].

Cross-Talk between Staphylococcus aureus and Other Staphylococcal Species via the agr Quorum Sensing System

Staphylococci are associated with both humans and animals. While most are non-pathogenic colonizers, Staphylococcus aureus is an opportunistic pathogen capable of causing severe infections. S. aureus virulence is controlled by the agr quorum sensing system responding to secreted auto-inducing peptides (AIPs) sensed by AgrC, a two component histidine kinase. agr loci are found also in other staphylococcal species and for Staphylococcus epidermidis, the encoded AIP represses expression of agr regulated virulence genes in S. aureus. In this study we aimed to better understand the interaction between staphylococci and S. aureus, and show that this interaction may eventually lead to the identification of new anti-virulence candidates to target S. aureus infections. Here we show that culture supernatants of 37 out of 52 staphylococcal isolates representing 17 different species inhibit S. aureus agr. The dog pathogen, Staphylococcus schleiferi, expressed the most potent inhibitory activity and was active against all four agr classes found in S. aureus. By employing a S. aureus strain encoding a constitutively active AIP receptor we show that the activity is mediated via agr. Subsequent cloning and heterologous expression of the S. schleiferi AIP in S. aureus demonstrated that this molecule was likely responsible for the inhibitory activity, and further proof was provided when pure synthetic S. schleiferi AIP was able to completely abolish agr induction of an S. aureus reporter strain. To assess impact on S. aureus virulence, we co-inoculated S. aureus and S. schleiferi in vivo in the Galleria mellonella wax moth larva, and found that expression of key S. aureus virulence factors was abrogated. Our data show that the S. aureus agr locus is highly responsive to other staphylococcal species suggesting that agr is an inter-species communication system. Based on these results we speculate that interactions between S. aureus and other colonizing staphylococci will significantly influence the ability of S. aureus to cause infection, and we propose that other staphylococci are potential sources of compounds that can be applied as anti-virulence therapy for combating S. aureus infections.

Primitive leiomyosarcoma of the breast: case report and review of the literature

Sarcomas of the breast account for under 1% of breast tumours. Leiomyosarcomas are less common, being a subgroup of sarcomas of the breast. Only 23 cases with immunohistochemical or electron microscopy confirmation are reported in the literature. The case of a 58-year-old woman with a leiomyosarcoma 4 cm in diameter in the upper external quadrant of the right breast is presented. Mammography and sonography were compatible with a fibroadenoma or phylloides tumour, and fine-needle aspiration (FNA) suggested medullary carcinoma. The patient underwent a Madden-type modified radical mastectomy and axillary lymphadenectomy. Adjuvant chemotherapy was implemented with Adriamycin (four cycles of 21 days). One year after surgery the patient is tumour free.

Endogenous endotoxemia of intestinal origin during cardiopulmonary bypass. Role of type of flow and protective effect of selective digestive decontamination

OBJECTIVE

To evaluate the possible related factors to endotoxemia and cytokine activation during the ischemic phase of extracorporeal surgery, and the effect of selective digestive decontamination (SDD) as a preventive measure.

DESIGN

Prospective, open, randomized trial.

SETTING

Two multidisciplinary ICUs (tertiary care hospitals).

PATIENTS

One hundred consecutive patients undergoing cardiopulmonary bypass (CPB), randomly allocated to two groups; gut decontamination (group I = 50 cases) and controls (group II = 50 cases).

INTERVENTIONS

Preoperative administration of oral non-absorbable antibiotics (polymyxin E, tobramycin and amphotericin B) versus no administration.

MEASUREMENTS AND RESULTS

The assessment of decontamination by means of the bacteriologic control of rectal swabs. Determinations of gastric intramucosal pH (gastric pHi) and plasma endotoxin, tumor necrosis factor (TNF) aNd interleukin-6 (IL-6) before surgery and during the ischemic and reperfusion phases of bypass. Rectal aerobic Gram-negative bacilli (AGNB) were significantly reduced in the treated patients and in 56% total eradication was achieved. Endotoxin, TNF and IL-6 plasma levels were significantly lower in this group. By contrast, both endotoxin and TNF/IL-6 levels and gastric pHi correlated with the type of surgical flow (pulsatile versus non-pulsatile).

CONCLUSIONS

SDD reduces the gut content of enterobacteria. This may explain the lower endotoxin and cytokine levels detected in decontaminated patients. In addition to SDD, the type of flow employed during bypass seems to influence endotoxemia and cytokine levels.

Genetics and mapping of new isozyme loci in Vicia faba L using trisomics

Polymorphism in ten enzyme systems (ACO, ACP, AAT, EST, FK, ME, NAG, PRX, 6PGD, and SOD) in Vicia faba L. was analyzed, revealing 13 loci, six of which have not been reported before. Inheritance, genetics, possible location, and linkage analysis were studied in 13 different F(2) populations trisomic for four of the six chromosomes (nos. 3, 4, 5, and 6) of the species. Each of these loci exhibited typical Mendelian inheritance except for those involved in the trisomic chromosome. Five loci have been assigned to a specific chromosome: Est-2 to chromosome 3, Fk-2 to chromosome 4, Prx-1 to chromosome 5, and Sod-1 and Pgd-p to chromosome 6. Nag-1 and Pgd-c displayed a linkage of 22.8 cM indicating a clear homology with chromosome 5 of garden pea on which both markers are syntenic.