Superantigen Production Research Articles

Fecal Proteolytic Bacteria and Staphylococcal Superantigens Are Associated With Abdominal Pain Severity in Irritable Bowel Syndrome.

Changes in the composition of the gut microbiota have been associated with the development of irritable bowel syndrome (IBS). However, to what extent specific bacterial species relate to clinical symptoms remains poorly characterized. We investigated the clinical relevance of bacterial species linked with increased proteolytic activity, histamine production, and superantigen (SAg) production in patients with IBS. Fecal (n = 309) and nasal (n = 214) samples were collected from patients with IBS and healthy volunteers (HV). Clinical symptoms and gut transit time were evaluated. Bacterial abundance in feces and nasal swabs as well as fecal trypsin-like activity were assessed. The percentage of fecal samples containing Staphylococcus aureus was significantly higher in IBS compared with HV. Forty-nine percent of S. aureus -positive fecal samples from patients with IBS were also positive for SAgs, compared with 12% of HV. Patients with IBS and positive fecal SAg-producing S. aureus reported higher pain scores than those without S. aureus . Moreover, increased fecal proteolytic activity was associated with abdominal pain. Fecal abundance of Paraprevotella clara and Alistipes putredinis was significantly decreased in IBS, particularly in samples with higher proteolytic activity. Patients with lower Alistipes putredinis or Faecalibacterium prausnitzii abundance reported more severe abdominal pain. In keeping with our preclinical findings, we show that increased presence of SAg-producing S. aureus in fecal samples of patients with IBS is associated with increased levels of abdominal pain. We also show that increased fecal proteolytic activity is associated with increased abdominal pain in patients with IBS.

Glycerol Monolaurate Contributes to the Antimicrobial and Anti-inflammatory Activity of Human Milk

Human milk has antimicrobial compounds and immunomodulatory activities. We investigated glycerol monolaurate (GML) in human milk versus bovine milk and infant formula for antimicrobial and anti-inflammatory activities. Human milk contained approximately 3000 µg/ml of GML, compared to 150 μg/ml in bovine milk and none in infant formula. For bacteria tested (Staphylococcus aureus, Bacillus subtilis, Clostridium perfringens, Escherichia coli), except Enterococcus faecalis, human milk was more antimicrobial than bovine milk and formula. The Enterococcus faecalis strain, which was not inhibited, produced reutericyclin, which is an analogue of GML and functions as a growth stimulant in bacteria that produce it. Removal of GML and other lipophilic molecules from human milk by ethanol extraction resulted in a loss of antibacterial activity, which was restored by re-addition of GML. GML addition caused bovine milk to become antimicrobial. Human milk but not bovine milk or formula inhibited superantigen and bacterial-induced IL-8 production by model human epithelial cells. GML may contribute beneficially to human milk compared to bovine milk or infant formula.

Streptococcal superantigen-induced expansion of human tonsil T cells leads to altered T follicular helper cell phenotype, B cell death and reduced immunoglobulin release.

SummaryStreptococcal pyrogenic exotoxin (Spe) A expression is epidemiologically linked to streptococcal tonsillo‐pharyngitis and outbreaks of scarlet fever, although the mechanisms by which superantigens confer advantage to Streptococcus pyogenes are unclear. S. pyogenes is an exclusively human pathogen. As the leucocyte profile of tonsil is unique, the impact of SpeA production on human tonsil cell function was investigated. Human tonsil cells from routine tonsillectomy were co‐incubated with purified streptococcal superantigens or culture supernatants from isogenic streptococcal isolates, differing only in superantigen production. Tonsil cell proliferation was quantified by tritiated thymidine incorporation, and cell surface characteristics assessed by flow cytometry. Soluble mediators including immunoglobulin were measured using enzyme‐linked immunosorbent assay. Tonsil T cells proliferated in response to SpeA and demonstrated typical release of proinflammatory cytokines. When cultured in the absence of superantigen, tonsil preparations released large quantities of immunoglobulin over 7 days. In contrast, marked B cell apoptosis and abrogation of total immunoglobulin (Ig)A, IgM, and IgG production occurred in the presence of SpeA and other superantigens. In SpeA‐stimulated cultures, T follicular helper (Tfh) cells showed a reduction in C‐X‐C chemokine receptor (CXCR)5 (CD185) expression, but up‐regulation of OX40 (CD134) and inducible T cell co‐stimulator (ICOS) (CD278) expression. The phenotypical change in the Tfh population was associated with impaired chemotactic response to CXCL13. SpeA and other superantigens cause dysregulated tonsil immune function, driving T cells from Tfh to a proliferating phenotype, with resultant loss of B cells and immunoglobulin production, providing superantigen‐producing bacteria with a probable survival advantage.

Update on association between Kawasaki disease and infection.

The relationship between infection and Kawasaki disease (KD) remains unclear. Infection has long been considered a key predisposing factor for KD. Bacterial and viral agents may be related to the onset of KD because of superantigen and cytokine production. Various bacterial and viral infections have been reported to be associated with KD, but the actual mechanism remains unknown. The higher association between KD and enterovirus has been well documented by using Taiwan National Health Insurance Research Database. However, no evidence has been obtained that various bacterial and viral infections induce KD. Comprehensive research, including infectious agents, should be conducted to elucidate the pathogenesis of KD.

Superantigens of Staphylococcus Aureus Colonization in Atopic Dermatitis and Treatment Efficacy of Oral Cefuroxim in Vietnamese Patients.

BACKGROUND:Atopic dermatitis (AD) is a common, chronic, relapsing, genetically determined inflammatory skin disorder. Staphylococcus aureus (S. aureus) plays an important role in the pathogenesis of AD. Atopic skin is susceptible to infection with S. aureus.AIM:This study was aimed to compare the skin S. aureus colonisation status and its secretion of superantigens in adult AD and healthy subjects and to evaluate the efficacy of two treatment regimens (oral cefuroxime plus topical betamethasone dipropionate 0.05% versus topical betamethasone dipropionate 0.05%) in AD patients.METHODS:A group of 128 AD and 40 healthy subjects were recruited in this study and treatment efficacy was assessed by the SCORAD score.RESULTS:S. aureus was found in skin lesions in 83.8% of AD patients while only 37.5% of healthy subjects possessed this kind of bacteria in the external nares (p < 0.001). Superantigen production was more common in S. aureus strains isolated from AD than the control group (58.6% versus 6.6%, p = 0.0006) and staphylococcal enterotoxin B was predominant (88.89%). 68 AD patients who had positive cultures with S. aureus were included in a clinical therapeutic trial. The isolated bacteria were all sensitive to cefuroxime. Patients were randomised to receive either oral cefuroxime 500 mg b.i.d. Plus topical betamethasone dipropionate 0.05% twice daily for 2 weeks (so-called group 1, 36 patients) or only topical betamethasone dipropionate 0.05% twice daily for 2 weeks (so-called group 2, 32 patients). The mean SCORAD scores of group 1 at baseline and after 1 and 2 weeks of treatment were 44.61, 26.69 and 16.61, respectively. The corresponding values for group 2 were 43.03, 32.53 and 23.41, respectively.CONCLUSION:The reduction in SCORAD scores was significantly higher in group 1 than group 2 in comparison to the baseline value of each study group (p = 0.003 after 1 week and p < 0.001 at the end of treatment).

Reduced pro-inflammatory responses to Staphylococcus aureus bloodstream infection and low prevalence of enterotoxin genes in isolates from patients on haemodialysis.

Patients with end-stage renal failure undergo regular haemodialysis (HD) and often develop episodes of Staphylococcus aureus bloodstream infection (BSI), which can re-occur. However, clinically, patients on HD, with S. aureus BSI, respond well to treatment, rarely developing overt signs of sepsis. We investigated the contributions of bacterial virulence and cytokine responses to the clinical course of S. aureus BSI in HD and non-HD patients. Seventy patients were recruited, including 27 (38.6%) patients on HD. Isolates were spa-typed and virulence and antimicrobial resistance gene carriage was investigated using DNA microarray analysis. Four inflammatory cytokines, IL-6, RANTES, GROγ and leptin, were measured in patient plasma on the day of diagnosis and after 7 days. There was no significant difference in the prevalence of genotypes or antimicrobial resistance genes in S. aureus isolates from HD compared to non-HD patients. The enterotoxin gene cluster (containing staphylococcal enterotoxins seg, sei, sem, sen, seo and seu) was significantly less prevalent among BSI isolates from HD patients compared to non-HD patients. Comparing inflammatory cytokine response to S. aureus BSI in HD patients to non-HD patients, IL-6 and GROγ were significantly lower (p = 0.021 and p = 0.001, respectively) in HD patients compared to other patients on the day of diagnosis and RANTES levels were significantly lower (p = 0.025) in HD patients on day 7 following diagnosis. Lowered cytokine responses in HD patients and a reduced potential for super-antigen production by infecting isolates may partly explain the favourable clinical responses to episodes of S. aureus BSI in HD patients that we noted clinically.

Prevalence of enterotoxin genes in Staphylococcus aureus colonising food handlers: does nasal carriage status matter?

This study investigated the association between the presence of staphylococcal enterotoxin (SE) genes and nasal carriage status, and determined temporal changes in the prevalence of these genes in Staphylococcus aureus strains isolated from healthy carriers between 2002 and 2011. Three large samples of food handlers recruited in 2002, 2003 and 2011 were nasally sampled on two occasions to determine S. aureus colonisation status. Those carrying the same spa type on both occasions were defined as persistent carriers. Genes for SEs SEA-SEU were amplified and associations between carriage status and presence of SE genes were investigated. Although 80% of nasal isolates harboured at least one SE gene over the sampling period, persistent carriers were significantly more likely to harbour enterotoxigenic S. aureus than transiently colonised subjects [odds ratio (OR) 2.52-3.06]. Strains from persistent carriers more commonly harboured sea, seb and sem. The prevalence of classical SE genes and sej, sem, sen, seo, seq and ses was stable over time, but seh, sel, sep, ser, set and selu increased significantly. Increased toxigenicity of isolates from persistent carriers is consistent with the elevated antibody levels to classical SEs previously reported in persistent carriers, supporting the hypothesis that superantigen production in the nasal cavity may enhance colonisation.

Vasculitis related to viral and other microbial agents.

Vasculitis due to infection may occur as a consequence of the inflammation of vessel walls due to direct or contiguous infection, type II or immune complex-mediated reaction, cell-mediated hypersensitivity, or inflammation due to immune dysregulation triggered by bacterial toxin and/or superantigen production. As immunosuppressive therapy administered in the absence of antimicrobial therapy may increase morbidity and fail to effect the resolution of infection-associated vascular inflammation, it is important to consider infectious entities as potential inciting factors in vasculitis syndromes. The causality between infection and vasculitis has been established in hepatitis B-associated polyarteritis nodosa (HBV-PAN) and hepatitis C-associated (cryoglobulinemic) vasculitis (HCV-CV). The review summarizes the recent literature on the pathophysiological mechanisms and the approaches to the management of HBV-PAN and HCV-CV. Roles of other viral and microbial infections, which either manifest as vasculitic syndromes or are implicated in the pathogenesis of primary vasculitides, are also discussed.

Functional overexpression and purification of a codon optimized synthetic four superantigens in Escherichia coli: Production of superantigens with improved safety and efficacy for cancer immunotherapy (LB582)

Bacterial superantigens (SAGs) are potent T cell stimulatory molecules and comprise a large family of disease‐associated proteins. The best‐characterized members of the superantigen family are staphylococcal enterotoxins (SEs), which are secreted by Staphylococcus aureus, and streptococcal pyrogenic exotoxins (SPEs), which are secreted by Streptococcus pyogenes Unlike conventional antigens they are not processed internally by antigen presenting cells (APC), and are thus not displayed as peptide antigen in the peptide‐binding groove of the MHC class II molecule. Superantigens bind to APCs on the outside of the MHC class II molecule and to T cells via the external face of the T cell receptor (TCR). This enables them to activate up to 20% of resting T cells, whilst conventional antigen presentation results in the activation of 0.001‐ 0.0001% of the T cell population. These biological properties of superantigens make them very attractive for use in immunotherapy.In this study, four synthetic genes coding for four different superantigens, SEA, SEB, TSST‐1 and SPEA were codon‐optimised and synthesized for maximum expression in E. coli using the vector pET28a.Our work indicated that in all cases the recombinant superantigens were expressed to 40% of the total host protein. We managed to optimise the condition to obtain 20% of the recombinant superantigens in a soluble form. The purification of the soluble His‐tagged recombinant superantigens have been achieved in a single step by Ni2+ charged column chromatography.The superantigenicity of each synthetic recombinant SEA, SEB, TSST‐1 and SPEA was determined by 2 methods. First method includes 3H‐thymidine incorporation assay as a measure of T‐cell proliferation i.e. T‐cell stimulation by modified SAGs. The second part of the superantigenicity assays includes measurement of cytokines produced by peripheral blood cells.The successful cloning and expression of four codon optimised synthetic superantigens genes will provide the recombinant protein for production of safe superantigen for cancer immunotherapy.Grant Funding Source: Anti‐doping lab‐Qatar

Superantigen profiling of Staphylococcus aureus infective endocarditis isolates

The frequency of superantigen production among Staphylococcus aureus isolates associated with endocarditis is not well defined. We tested 154 S. aureus isolates from definite infective endocarditis cases for the presence of staphylococcal enterotoxins A-E, H, and TSST-1 by PCR, enzyme-linked immunosorbent assay, and using an HLA-DR3 transgenic mouse splenocyte proliferation assay. Sixty-three isolates (50.8%) tested positive for at least 1 superantigen gene, with 21 (16.9%) testing positive for more than 2. tst (28.6%) was most common, followed by seb (27%), sea (22.2%), sed (20.6%), see (17.5%), and sec (11.1%). Of 41 methicillin-resistant S. aureus, 21 had superantigen genes, with sed being more frequently detected in this group compared to methicillin-susceptible S. aureus (P < 0.05). Superantigen genes were not associated with mortality (P = 0.81). 75% of PCR-positive isolates induced robust splenocyte proliferation. Overall, more than half of S. aureus isolates causing endocarditis carry superantigen genes, of which most are functional.

Staphylococcal and Streptococcal Superantigen Exotoxins

SUMMARY This review begins with a discussion of the large family of Staphylococcus aureus and beta-hemolytic streptococcal pyrogenic toxin T lymphocyte superantigens from structural and immunobiological perspectives. With this as background, the review then discusses the major known and possible human disease associations with superantigens, including associations with toxic shock syndromes, atopic dermatitis, pneumonia, infective endocarditis, and autoimmune sequelae to streptococcal illnesses. Finally, the review addresses current and possible novel strategies to prevent superantigen production and passive and active immunization strategies.

Treatment with an Oxazolidinone Antibiotic Inhibits Toxic Shock Syndrome Toxin-1 Production in MRSA-Infected Burn Wounds

Mortality rates in burn patients increase if they experience complications of infection. Frequently, the organisms associated with such infections are Staphylococci, including antibiotic-resistant species such as methicillin-resistant Staphylococcus aureus. Virulence factor production can further complicate treatment as a localized toxin presence may derail the healing process and allow a more invasive infection, while a toxin that becomes systemic can induce shock and cause host immune disruption. Male rats were anesthetized and subjected to full-thickness burn wounds. One day postinjury, wounds were inoculated with Toxic Shock Syndrome Toxin-1-producing methicillin-resistant S. aureus. Animals were then divided into three treatment groups: vancomycin, linezolid, or positive control. For nine additional days, animals received twice-daily antibiotics and wound assessments, blood draws, and wound biopsies were performed. All animals had wound quantitative cultures that exceeded 1 × 10 colony forming units (CFU) per gram 1 day after inoculation. Linezolid treatment significantly reduced the bacterial counts in the wounds. Positive controls and vancomycin-treated animals had toxins in their wounds by day 5 and this remained throughout the study (ranging from 20-80 ng/ml). Linezolid-treated animals had significant decrease in toxin production (< 5 ng/ml), and in most cases toxins were undetectable. No animals became systemically infected with bacteria at any point during the study. Superantigen production in burn wounds has morbid consequences in terms of long-term wound healing. A S. aureus burn wound infection model was created that allowed the study of the effect of two standard-use antibiotics on local burn wound pathophysiology. Most noteworthy is that low-dose linezolid arrested toxin production in the wound.

Glycerol monolaurate antibacterial activity in broth and biofilm cultures.

BackgroundGlycerol monolaurate (GML) is an antimicrobial agent that has potent activity against gram-positive bacteria. This study examines GML antibacterial activity in comparison to lauric acid, in broth cultures compared to biofilm cultures, and against a wide range of gram-positive, gram-negative, and non-gram staining bacteria.Methodology/Principal FindingsGML is ≥200 times more effective than lauric acid in bactericidal activity, defined as a ≥3 log reduction in colony-forming units (CFU)/ml, against Staphylococcus aureus and Streptococcus pyogenes in broth cultures. Both molecules inhibit superantigen production by these organisms at concentrations that are not bactericidal. GML prevents biofilm formation by Staphylococcus aureus and Haemophilus influenzae, as representative gram-positive and gram-negative organisms, tested in 96 well microtiter plates, and simultaneously is bactericidal for both organisms in mature biofilms. GML is bactericidal for a wide range of potential bacterial pathogens, except for Pseudomonas aeruginosa and Enterobacteriaceae. In the presence of acidic pH and the cation chelator ethylene diamine tetraacetic acid, GML has greatly enhanced bactericidal activity for Pseudomonas aeruginosa and Enterobacteriaceae. Solubilization of GML in a nonaqueous delivery vehicle (related to K-Y Warming®) enhances its bactericidal activity against S. aureus. Both R and S, and 1 and 2 position lauric acid derivatives of GML exhibit bactericidal activity. Despite year-long passage of Staphylococcus aureus on sub-growth inhibitory concentrations of GML (0.5 x minimum bactericidal concentration), resistance to GML did not develop.Conclusions/SignificanceGML may be useful as a broad-spectrum human or animal topical microbicide and may be useful as an environmental surface microbicide for management of bacterial infections and contamination.

Methicillin-resistant Staphylococcus-aureus-associated glomerulonephritis on the decline: decreased incidence since the 1990s

We believe that bacterial-infection-associated glomerulonephritis (GN), so-called methicillin-resistant Staphylococcus aureus (MRSA)-GN, was exterminated in Japan. The control of bacterial infection is the most important part of infection-associated GN. In 1990s Japan, hospital-associated MRSA (HA-MRSA) caused MRSA-GN outbreaks. On the other hand, MRSA-GN incidence has been quite limited since 2000. This epidemiological transition suggests that antibacterial therapies and health programs for HA-MRSA infection in Japan were effective against MRSA-GN. Moreover, it appears that staphylococcal superantigens act in the pathogenesis of GN. The change of superantigen production might have influenced to the disappearance of MRSA-GN. If HA-MRSA-producing superantigen outbreaks occur in developing countries, our experience in Japan can provide guiding principles for preventing and eradicating GN.

Effects of pimecrolimus cream 1% in the treatment of patients with atopic dermatitis who demonstrate a clinical insensitivity to topical corticosteroids: a randomized, multicentre vehicle-controlled trial

Colonization with Staphylococcus aureus in atopic dermatitis (AD) is often associated with worsening of clinical symptoms. Staphylococcus aureus produces superantigens that contribute to cutaneous inflammation and corticosteroid (CS) resistance. To investigate the relationship between CS insensitivity, S. aureus colonization and superantigen production in AD, and to explore the efficacy of pimecrolimus cream in CS-insensitive AD. This was a randomized, double-blind, vehicle-controlled, multicentre, parallel-group study. Seventy-three patients with AD, aged 2-49 years, who had a documented clinical insensitivity to topical CS, were recruited. The primary efficacy parameters combined laboratory (including S. aureus colonization, superantigens) and clinical assessments [including Eczema Area and Severity Index (EASI), whole body Investigator's Global Assessment (IGA), pruritus assessment score, patient's assessment score of disease control]. An increase in S. aureus counts correlated with worsening of clinical score (week 6 vs. baseline) when assessed by IGA, pruritus severity and patient assessment. The presence of superantigens correlated with this worsening. During the 6-week double-blind phase, disease improvement in the pimecrolimus cream group was demonstrated by decreasing EASI scores compared with vehicle. Mean EASI scores for the head and neck showed greater improvement in the pimecrolimus cream group than in the vehicle group at all observed time points. In a cohort of patients with clinical insensitivity to CS there was a significant positive correlation between S. aureus and disease severity. Results suggest that for some of these patients, treatment with pimecrolimus cream 1% is useful, especially in the head/neck area.

IgE response to staphylococcal enterotoxins in adenoid tissues from atopic children

To evaluate local production of staphylococcal superantigen (SAg)-specific IgE in adenoid tissue and to compare its prevalence with that in the tonsil and serum, as well as its relationship with markers of allergic inflammation within adenoid tissue. Prospective randomized study. We recruited 18 atopic children who had rhinitis symptoms and were sensitized to more than one common aeroallergen, and 22 nonatopic children undergoing adenotonsillectomy. Immunoassays were performed using adenoid tissue homogenate to quantify the levels of three staphylococcal SAg-specific IgE (SEA, SEB, and TSST-1), total IgE, eosinophil cationic protein (ECP), mast cell tryptase, and soluble CD23. Three kinds of SAg-specific IgE were detected in the adenoid and tonsil tissues of atopic patients, but not in those of nonatopic patients. In atopic children, the prevalence of SEA-, SEB-, and TSST-1-specific IgE in adenoid tissues (61.1%, 27.8%, 33.3%, respectively) were higher than those in tonsil tissues (38.9%, 5.6%, 11.1%, respectively) and in sera (11.1%, 27.8%, 16.7%, respectively). Subjects with high SEA levels showed significantly higher serum and adenoid total IgE, with higher eosinophilia. Significant correlations were noted between SAg-specific IgE levels and tryptase levels in adenoid tissue. Local specific IgE response to staphylococcal SAgs, especially SEA may contribute to ongoing allergic inflammation in adenoid tissue from atopic children.

Membranoproliferative Glomerulonephritis in Patients with Cystic Fibrosis: Coincidence or Comorbidity? A Case Series

Cystic fibrosis (CF) is perceived as a childhood illness. However, with advances in medical science, patients are enjoying lives extending well into adulthood. This article reviews two cases of membranoproliferative glomerulonephritis (MPGN) in adults with CF. One patient with severe CF pulmonary disease had concomitant renal failure during hospitalization for a pulmonary exacerbation. Subsequent evaluations, including complement levels, were consistent with MPGN. The second patient had been recently diagnosed with colon cancer and was found to be suffering from acute renal failure. Diagnostic evaluation likewise confirmed the MPGN diagnosis. Immunologic associations linking CF and MPGN, including derangements in the complement system and the effects of superantigen production, are reviewed.

Superantigens SPEA and SMEZ do not affect secretome expression in Streptococcus pyogenes

The superantigens, toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxin B (SEB), were recently reported to repress global exoprotein synthesis in Staphylococcus aureus. To investigate if this phenomenon could be observed in a different Gram-positive pathogen, the effects of two major Streptococcus pyogenes superantigens on streptococcal secretome expression were examined. Using mutagenesis and genetic complementation, we demonstrated that neither streptococcal pyrogenic exotoxin A (SPEA) nor streptococcal mitogenic exotoxin Z (SMEZ) had any consistent effect on global protein expression or on transcription of genes encoding the secreted exoproteins, DNase B, SPEB and SPEG. In S. pyogenes, superantigen production does not appear to have a major regulatory role.

Rat Model of Staphylococcal Enterotoxin B-Induced Rhinosinusitis

ObjectivesIt has been proposed that microbial persistence, superantigen (SA) production, and host T-cell response may be involved in the development of chronic rhinosinusitis. According to the SA hypothesis, a single intranasal application of SA such as staphylococcal enterotoxin B (SEB) may induce chronic eosinophilic rhinosinusitis. This study aimed to develop a rat model of rhinosinusitis induced by intranasally applied SEB.MethodsForty µL of SEB (100 µg/mL) or phosphate buffered saline was applied intranasally through each naris in 4 week-old Sprague-Dawley test rats (N=36) and controls (N=16), respectively. Following sacrifice at 1, 5, 14, and 28 days, the obtained nasal cavity and sinuses were prepared for histologic investigation. The histologic sections were examined in a blind manner for the ratio of the sinus spaces occupied by inflammatory cell clusters and the number of inflammatory cells in the lamina propria.ResultsInfiltration of neutrophils in the lamina propria and appearance of neutrophil clusters in the sinus spaces were observed in the SEB-applied rats. The ratio of the sinus spaces occupied by neutrophil clusters and the number of neutrophils infiltrated in the lamina propria increased significantly at day 1 as compared with the control rats.ConclusionIntranasally applied SEB induces acute neutrophilic rhinosinusitis in rats. Eosinophilic inflammation was not demonstrated. The mere presence of SA in the nose does not necessarily induce SA-induced inflammation, as suggested by the SA hypothesis.

Bacteriology of the Sinus Cavities of Asymptomatic Individuals after Endoscopic Sinus Surgery

To determine the resident flora and the level of bacterial presence of the healthy sinus cavity post-endoscopic sinus surgery (ESS). University-based prospective trial. Subjects included asymptomatic patients who had undergone ESS for inflammatory disease more than 12 weeks previously. Endoscopic cultures of the sinus cavities were performed with swab and a novel lavage technique and were processed for identification of bacterial species and the level of bacterial presence. Thirty-two patients were recruited. Bacterial organisms were recovered in 97% of subjects (mean 1.5 organisms/patient). The flora predominantly consisted of coagulase-negative staphylococci (69%) and diphtheroids (25%). Staphylococcus aureus was recovered in 31% of subjects and Pseudomonas aeruginosa in 3% only. No gram-negative rods were recovered in any individual. The Gram stains of 29 individuals were identified; 20 (69%) had no white blood cells, 9 (31%) had 1+ white blood cells, and none had >1 white blood cells. All quantitative lavage fluid cultures were negative at the 10(4) detection level. Coagulase-negative staphylococci, diphtheroids, and S. aureus constitute the predominant flora of the healthy post-ESS sinus cavity and probably represent colonization of the cavity by nasal flora from the contiguous nasal mucosa. These data offer a basis for interpreting sinus cultures obtained in symptomatic patients after ESS. S. aureus may be frequently recovered in asymptomatic patients; thus, not all instances of S. aureus recovery on culture require therapy. Future testing of individuals with this organism will probably have to be modified to better assess factors associated with pathogenicity, such as bacterial load, biofilm formation, or superantigen production. In contrast, gram-negative rods and P. aeruginosa should probably be treated when identified on culture.