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Molecular epidemiologic analysis of the type A streptococcal exotoxin (erythrogenic toxin) gene (speA) in clinical Streptococcus pyogenes strains.

A molecular epidemiology analysis was performed with over 440 clinical isolates of Streptococcus pyogenes obtained from 11 different countries in order to determine the frequency of occurrence of the type A streptococcal exotoxin (erythrogenic toxin) gene (speA) among group A strains. The colony hybridization technique employing a specific internal fragment of the speA gene was used for initial screening, and all positive results were further confirmed by the Southern hybridization technique. Among over 300 general strains obtained from patients with a variety of diseases, except scarlet fever (such as tonsillitis, impetigo, cellulitis, pyoderma, abscess, rheumatic fever, and glomerulonephritis), 15% were found to contain the speA gene. Among a group of 146 strains obtained from individuals described as having scarlet fever, 45% were shown to contain the speA gene. Further analysis of the data indicated that strains with certain M- or T-type surface antigens showed a higher (such as M and T types 1 and 3/13) or lower (such as M2, M12, T4, T5, and T28) tendency to contain the speA gene. No correlation was found between speA content of a strain and the ability to cause a specific disease, although strains possessing the speA gene were more likely to be associated with scarlet fever and rheumatic fever than with other types of disease.

Bacterial Proteins↗

Identification of the Staphylococcus aureus etd pathogenicity island which encodes a novel exfoliative toxin, ETD, and EDIN-B.

We identified a novel pathogenicity island in Staphylococcus aureus which contains open reading frames (ORFs) similar to the exfoliative toxin (ET) gene, glutamyl endopeptidase gene, and edin-B gene in tandem and the phage resistance gene, flanked by hsdM, hsdS (restriction and modification system), and IS256. The protein encoded by the ET-like gene showed 40, 59, and 68% amino acid sequence identities with exfoliative toxin A (ETA), exfoliative toxin B (ETB), and Staphylococcus hyicus ETB (ShETB), respectively. When injected into neonatal mice, the recombinant protein derived from the ET-like gene induced exfoliation of the skin with loss of cell-to-cell adhesion in the upper part of the epidermis as observed in histological examinations, just as was found in neonatal mice injected with ETA or ETB. Western blot analysis indicated that the recombinant protein is serologically distinct from ETA and ETB. Therefore, the product encoded by this new ORF is a new ET member produced by S. aureus and is termed ETD. ETD did not induce blisters in 1-day-old chickens. In the skins of mice injected with ETD, cell surface staining of desmoglein 1 (Dsg1), a cadherin type cell-to-cell adhesion molecule in desmosomes, was abolished without affecting that of desmoglein 3 (Dsg3). Furthermore, in vitro incubation of the recombinant extracellular domains of Dsg1 and Dsg3 with the recombinant protein demonstrated that both mouse and human Dsg1, but not Dsg3, were directly cleaved in a dose-dependent manner. These results demonstrate that ETD and ETA induce blister formation by identical pathophysiological mechanisms. Clinical strains positive for edin-B were suggested to be clonally associated, and all edin-B-positive strains tested were positive for etd. Among 18 etd-positive strains, 12 produced ETD extracellularly. Interestingly, these strains are mainly isolated from other sources of infections and not from patients with bullous impetigo or staphylococcal scalded-skin syndrome. This strongly suggests that ETD might play a pathogenic role in a broader spectrum of bacterial infections than previously considered.

Amino Acid Sequence↗

Relationships between Staphylococcus aureus genetic background, virulence factors, agr groups (alleles), and human disease.

The expression of most Staphylococcus aureus virulence factors is controlled by the agr locus, which encodes a two-component signaling pathway whose activating ligand is an agr-encoded autoinducing peptide (AIP). A polymorphism in the amino acid sequence of the AIP and of its corresponding receptor divides S. aureus strains into four major groups. Within a given group, each strain produces a peptide that can activate the agr response in the other member strains, whereas the AIPs belonging to different groups are usually mutually inhibitory. We investigated a possible relationship between agr groups and human S. aureus disease by studying 198 S. aureus strains isolated from 14 asymptomatic carriers, 66 patients with suppurative infection, and 114 patients with acute toxemia. The agr group and the distribution of 24 toxin genes were analyzed by PCR, and the genetic background was determined by means of amplified fragment length polymorphism (AFLP) analysis. The isolates were relatively evenly distributed among the four agrgroups, with 61 strains belonging to agr group I, 49 belonging to group II, 43 belonging to group III, and 45 belonging to group IV. Principal coordinate analysis performed on the AFLP distance matrix divided the 198 strains into three main phylogenetic groups, AF1 corresponding to strains of agr group IV, AF2 corresponding to strains of agr groups I and II, and AF3 corresponding to strains of agr group III. This indicated that the agr type was linked to the genetic background. A relationship between genetic background, agr group, and disease type was observed for several toxin-mediated diseases: for instance, agr group IV strains were associated with generalized exfoliative syndromes, and phylogenetic group AF1 strains with bullous impetigo. Among the suppurative infections, endocarditis strains mainly belonged to phylogenetic group AF2 and agr groups I and II. While these results do not show a direct role of the agr type in the type of human disease caused by S. aureus, the agr group may reflect an ancient evolutionary division of S. aureus in terms of this species' fundamental biology.

Alleles↗

Active and passive intranasal immunizations with streptococcal surface protein C5a peptidase prevent infection of murine nasal mucosa-associated lymphoid tissue, a functional homologue of human tonsils.

C5a peptidase, also called SCPA (surface-bound C5a peptidase), is a surface-bound protein on group A streptococci (GAS), etiologic agents for a variety of human diseases including pharyngitis, impetigo, toxic shock, and necrotizing fasciitis, as well as the postinfection sequelae rheumatic fever and rheumatic heart disease. This protein is highly conserved among different serotypes and is also expressed in human isolates of group B, C, and G streptococci. Human tonsils are the primary reservoirs for GAS, maintaining endemic disease across the globe. We recently reported that GAS preferentially target nasal mucosa-associated lymphoid tissue (NALT) in mice, a tissue functionally analogous to human tonsils. Experiments using a C5a peptidase loss-of-function mutant and an intranasal infection model showed that this protease is required for efficient colonization of NALT. An effective vaccine should prevent infection of this secondary lymphoid tissue; therefore, the potential of anti-SCPA antibodies to protect against streptococcal infection of NALT was investigated. Experiments showed that GAS colonization of NALT was significantly reduced following intranasal immunization of mice with recombinant SCPA protein administered alone or with cholera toxin, whereas a high degree of GAS colonization of NALT was observed in control mice immunized with phosphate-buffered saline only. Moreover, administration of anti-SCPA serum by the intranasal route protected mice against streptococcal infection. These results suggest that intranasal immunization with SCPA would prevent colonization and infection of human tonsils, thereby eliminating potential reservoirs that maintain endemic disease.

Adhesins, Bacterial↗

The Streptococcus pyogenes mannose phosphotransferase system (Man-PTS) influences antimicrobial activity and niche-specific nasopharyngeal infection.

Streptococcus pyogenes is a human-adapted pathogen that can cause multiple diseases, including pharyngitis and skin infections. Although this bacterium produces many virulence factors, how S. pyogenes competes with the host microbiota is not well understood. Here, we detected antimicrobial activity from S. pyogenes MGAS8232 that prevented the growth of Micrococcus luteus. This activity was produced when cells were grown in 5% CO2 in M17 media supplemented with galactose; however, the addition of alternative sugars coupled with genome sequencing experiments revealed that the antimicrobial phenotype was not related to classical bacteriocins. To further determine genes involved in the production of this activity, a transposon mutant library in S. pyogenes MGAS8232 identified the mannose phosphotransferase system (Man-PTS), a major sugar transporter, as important for the antimicrobial phenotype. Loss-of-function transposon mutants linked to the antimicrobial activity were identified to also be involved in alternative sugar utilization, and additionally, the Man-PTS was further identified from an inadvertent secondary mutation in a bacteriocin operon mutant. Sugar utilization in the Man-PTS mutants demonstrated that galactose, mannose, and N-acetylglucosamine utilization was impaired. RNA-seq experiments in high and low glucose concentrations further characterized the Man-PTS as a glucose transporter; however, transcriptional regulators or virulence factors were not affected with the loss of the Man-PTS. Deletion of Man-PTS demonstrated defects in a mouse model of nasopharyngeal infection but not skin infection. This work suggests that the ability of S. pyogenes to utilize alternative sugars presented by glycans may play a role in acute infection and interactions with the endogenous microbial population existing in the nasopharynx.IMPORTANCEStreptococcus pyogenes is responsible for over 500,000 deaths per year primarily due to invasive infections and post-infection sequelae, although the most common manifestations include pharyngitis and impetigo. S. pyogenes can adapt to its environment through alternative sugar metabolism. Here, we identified an antimicrobial phenotype that was not bacteriocin-related but a by-product of alternative sugar metabolism. The mannose phosphotransferase system was involved in the production of the antimicrobial and was also important for S. pyogenes to utilize alternative sugars and establish nasopharyngeal infection but not skin infection. Overall, this study identified potential strategies used by S. pyogenes for interactions with the endogenous microbiota and further elucidated the importance of sugar metabolism in acute upper respiratory tract infection.

Streptococcus pyogenes↗

Effect of ethidium bromide on elimination of exfoliative toxin and bacteriocin production in Staphylococcus aureus.

The scalded skin syndrome has been associated with phage group II staphylococci. The clinical manifestations of scalded skin syndrome, Ritter's disease, scarlatiniform erythema, and localized bullous impetigo, are due to the production of an extracellular protein, designated exfoliative toxin. Phage group II staphylococci can also produce an extracellular protein, bacteriocin, which is bacteriocidal for specific gram-positive microorganisms. Strain UT 0007 produces both bacteriocin and exfoliative toxin which appear to be products of extrachromosomal genes. These genes are jointly eliminated from strain UT 0007 after growth in either ethidium bromide or at high temperatures.

Animals↗

Epidemiological investigation of exfoliative toxin-producing Staphylococcus aureus strains in hospitalized patients.

The incidence of exfoliative toxin-producing strains of Staphylococcus aureus was studied. Samples from hospitalized patients of all ages and samples from infants less than 6 weeks old were screened; out of 2,632 coagulase-positive S. aureus strains tested, 6.2% synthesized exfoliative toxin. The clinical features could be assessed in 86 patients harboring exfoliative toxin-producing staphylococci. Skin lesions (pustules, blisters, and bullous impetigo) could be observed only when the exfoliative toxin-positive strains were isolated from the skin. Phage nongroup II strains seemed less skin pathogenic than phage group II strains. Outbreaks and sporadic cases were observed.

Animals↗

Skin disease presenting as an outbreak of pseudobacteremia in a laboratory worker.

An outbreak of pseudobacteremia due to Streptococcus pyogenes (group A streptococci [GAS]) and methicillin-susceptible Staphylococcus aureus (MSSA) was traced to the venting procedure for aerobic bottles prior to their loading into the incubator of the BacT/Alert analyzer (Organon Teknika). Bacteria shed by a laboratory worker suffering from impetigo and cellulitis contaminated the aerobic bottles of 10 patients. All blood culture isolates, in addition to the isolates from the laboratory worker, were of the same GAS M and T types. All MSSA isolates from blood cultures and the index case's hands had the same lytic phage profile. Procedural breakdowns were identified in the laboratory. Bottles were vented outside the biological safety cabinet, gloves were not worn, and unprotected needles were used for the venting procedure. The source of the aspirated bacteria that contaminated the bottles was identified and the index case was treated promptly.

Bacteremia↗

Sensitive and specific detection of staphylococcal epidermolysins A and B in broth cultures by flow cytometry-assisted multiplex immunoassay.

Two of the most common bacterial skin infections of young infants and children are bullous impetigo due to Staphylococcus aureus and its more acute form, staphylococcal scalded skin syndrome. Epidermolysin A (ETA), ETB and, possibly, ETD are responsible for these diseases, which may appear as epidemics in pediatric patients. We tested the reliability of a flow cytometry-assisted multiplex immunoassay (Bio-Plex system) for the detection of ETA and ETB. The Bio-Plex system was found to be highly specific and highly sensitive for toxin concentrations of between 2 and 80,000 pg/ml. The results of this assay were 100% identical to the results of a PCR-based method. We demonstrated that this test did not generate any cross-reactions with ETD-producing isolates. The level of detection of ETB by this test differed according to culture conditions and from isolate to isolate; these results must be taken into account for diagnostic purposes.

Exfoliatins↗

Frequency of serotypes of Streptococcus pyogenes in different diseases.

During an 18-month period 1,002 strains of Streptococcus pyogenes, consecutively isolated in the laboratory from a wide variety of lesions, were typed by the precipitin and slide-agglutination tests. The relative frequency of serotypes in different diseases was examined and a close association between type 4 in scarlet fever and type 3.13 in impetigo noted. An apparent lack of any relationship between particular serotypes and streptococcal sore throat was evident. The difficulty of distinguishing the more virulent types of Str. pyogenes and correlating a type-specific disease relationship is discussed.

Humans↗

Diagnosis of cutaneous tuberculosis in biopsy specimens by PCR and southern blotting.

AIMS: To evaluate the use of a gene amplification and hybridisation method for detecting mycobacterial nucleic acid as a possible diagnostic method for cutaneous tuberculosis infection. METHODS: Biopsy specimens from 20 patients with various skin conditions of possible tuberculous aetiology were studied. Six patients had ulcerative nodules, seven lupiform lesions, two non-necrotic granulomas, one scrofulous lichen, one impetigo, one erythematosus lesions, one warty lesions, and one suspected tuberculous lipoma. Biopsy specimens were stained using Ziehl-Neelsen stain and cultured in Lowenstein-Jensen medium. DNA was extracted and then amplified by PCR using primers specific for the Mycobacterium tuberculosis complex. Specificity was confirmed by Southern blotting. RESULTS: Of the specimens, 30% were positive for mycobacteria on staining with Ziehl-Neelsen stain, 60% were culture positive and 85% PCR positive. Only 35.2% of specimens were positive with all three techniques. A further 32.5% were both culture and PCR positive. All PCR negative samples were also negative when cultured or stained with Ziehl-Neelsen stain. Of the PCR positive specimens, 29.4% were negative when cultured or stained. CONCLUSIONS: PCR, using suitable primers, is an efficient and sensitive method for the diagnosis of cutaneous tuberculosis.

Biopsy↗

Activity of nadifloxacin (OPC-7251) and seven other antimicrobial agents against aerobic and anaerobic Gram-positive bacteria isolated from bacterial skin infections.

BACKGROUND AND METHODS: The in vitro activity of nadifloxacin (OPC-7251), a novel topical fluoroquinolone, was assessed and compared with those of ofloxacin, oxacillin, flucloxacillin, cefotiam, erythromycin, clindamycin, and gentamicin against 144 Gram-positive bacteria: 28 Staphylococcus aureus, 10 Streptococcus spp., 68 coagulase-negative staphylococci (CNS), 36 Propionibacterium acnes, and 2 Propionibacterium granulosum strains. All strains originated from bacterial-infected skin disease and were isolated from patients with impetigo, secondary infected wounds, folliculitis and sycosis vulgaris, and impetiginized dermatitis. In vitro susceptibility of all clinical isolates was tested by agar dilution procedure and minimum inhibitory concentrations (MICs) were determined. RESULTS: Nadifloxacin was active against all aerobic and anaerobic isolates. MIC(90) (MIC at which 90% of the isolates are inhibited) was 0.1 microg/ml for S. aureus, 0.78 microg/ml for both Streptococcus spp. and CNS, and 0.39 microg/ml for Propionibacterium spp. On the other hand, resistant strains with MICs exceeding 12.5 mug/ml were found in tests with the other antibiotics. For both CNS and Propionibacterium acnes, MIC(90) values > or =100 microg/ml were demonstrated for erythromycin. Ofloxacin, cefotiam, erythromycin, clindamycin and gentamicin exhibited MIC(90) values < or =1 microg/ml for some bacterial species tested. Both oxacillin and flucloxacillin were active against all investigated bacterial species with MIC(90) values < or =1 microg/ml. CONCLUSION: In summary, nadifloxacin, a topical fluoroquinolone, was found to be highly active against aerobic and anaerobic bacteria isolated from patients with infected skin disease, and seems to be a new alternative for topical antibiotic treatment in bacterial skin infections.

Administration, Topical↗

Quality control in chronic wound management: the role of local povidone-iodine (Betadine) therapy.

BACKGROUND: The treatment of venous leg ulcers is often inadequate, because of incorrect diagnosis, overuse of systemic antibiotics and inadequate use of compression therapy. Stasis dermatitis related to chronic venous insufficiency accompanied by infected superficial ulcers must be differentiated from erysipelas, cellulitis and contact eczema. OBJECTIVES: To assess the effectiveness of (1) topical povidone-iodine with and (2) without compression bandages, (3) to compare the efficacy of systemic antibiotics and topical antimicrobial agents to prevent the progression of superficial skin ulcers. PATIENTS AND METHODS: 63 patients presenting ulcerated stasis dermatitis due to deep venous refluxes were included in the study. The clinical stage of all patients was homogeneous determined by clinical, aetiological, anatomical and pathological classification. They were examined by taking a bacteriological swab from their ulcer area. Compression bandages were used in a total of 42 patients. Twenty-one patients with superficial infected (Staphylococcus aureus) ulcers were treated locally with povidone-iodine (Betadine), and 21 patients were treated with systemic antibiotics (amoxicillin). Twenty-one patients were treated locally with Betadine but did not use compression. The end point was the time of ulcus healing. The healing process of the ulcers was related to the impact of bacterial colonization and clinical signs of infection. RESULTS: Compression increases the ulcer healing rate compared with no compression. Using the same local povidone-iodine (Betadine) treatment with compression bandages is more effective (82%) for ulcus healing than without compression therapy (62%). The healing rate of ulcers treated with systemic antibiotics was not significantly better (85%) than that of the Betadine group. Using systemic antibiotics, the relapse rate of superficial bacterial infections (impetigo, folliculitis) was significantly higher (32%) than in patients with local disinfection (11%). CONCLUSION: Compression is essential in the mobilization of the interstitial lymphatic fluid from the region of stasis dermatitis. Topical disinfection and appropriate wound dressings are important to prevent wound infection. Systemic antibiotics are necessary only in systemic infections (fever, lymphangitis, lymphadenopathy, erysipelas).

Aged↗

Decreased platelet counts and decreased platelet serotonin in poststreptococcal nephritis.

Mean platelet survival time in patients with acute poststreptococcal glomerulonephritis (APSGN) is reduced to 50-60% of the control values, and glomerular deposits of platelet factor 4 are found in these patients. In order to investigate further systemic platelet changes of pathogenic, clinical or prognostic significance, we measured the platelet serotonin (5-HT) content and the blood platelet counts during the 1st week of the disease in 27 patients with APSGN. Platelet 5-HT was significantly reduced in patients with APSGN as compared with patients with impetigo without glomerular involvement (785 +/- 54 vs. 1,329 +/- 94 ng 5-HT/10(9) platelets; p < 0.001). Similarly, the mean blood platelet count was reduced to 247 +/- 16 x 10(3) as compared with 303 +/- 14 x 10(3) in the controls (p < 0.05). Thirteen (48%) of these patients had individual values of platelet 5-HT lower than the 95% confidence interval calculated in the control group. No significant correlation was observed between the concentration of 5-HT and either the severity of the disease judged by the amount of urinary protein excretion and the serum creatinine value or the presence of circulating immune complexes. Significant correction of the platelet 5-HT content (to 1,180 +/- 111 ng/10(9) platelets; p < 0.01) and of the platelet counts (to 309 +/- 21 x 10(3); p < 0.01) were observed in the longitudinal study at least 2 weeks later. Platelet activation, with secretion of granular content and increased consumption, may explain these findings. Additionally, the reduced mean age of the circulating platelets could contribute to their decreased 5-HT levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

Natural population dynamics and expansion of pathogenic clones of Staphylococcus aureus.

The population structure of Staphylococcus aureus carried by healthy humans was determined using a large strain collection of nonclinical origin (n = 829). High-throughput amplified fragment length polymorphism (AFLP) analysis revealed 3 major and 2 minor genetic clusters of S. aureus, which were corroborated by multilocus sequence typing. Major AFLP cluster I comprised 44.4% of the carriage isolates and showed additional heterogeneity whereas major AFLP groups II and III presented 2 homogeneous clusters, including 47.3% of all carriage isolates. Coanalysis of invasive S. aureus strains and epidemic methicillin-resistant S. aureus (MRSA) revealed that all major clusters contained invasive and multiresistant isolates. However, clusters and subclusters with overrepresentation of invasive isolates were also identified. Bacteremia in elderly adults, for instance, was caused by a IVa cluster-derived strain significantly more often than by strains from other AFLP clusters. Furthermore, expansion of multiresistant clones or clones associated with skin disease (impetigo) was detected, which suggests that epidemic potential is present in pathogenic strains of S. aureus. In addition, the virulence gene encoding Panton-Valentine leukocidin was significantly enriched in S. aureus strains causing abscesses and arthritis in comparison with the carriage group. We provide evidence that essentially any S. aureus genotype carried by humans can transform into a life-threatening human pathogen but that certain clones are more virulent than others.

Cloning, Molecular↗

Treatment of skin and soft tissue infections with cefadroxil, a new oral cephalosporin.

Oral cefadroxil in doses of 0-6-1-8 g per day given on twice or three times daily schedules was effective in the treatment of thirty-six patients with infections such as abscesses, carbuncles, cellulitis, furunculosis and impetigo. Staphylococcus aureus strains and beta-haemolytic streptococci, alone or in combination, were cultured from lesions before treatment. In vitro studies with test discs showed that all the organisms were sensitive to cefadroxil, but twenty-three of twenty-nine S aureus strains and one of the seven streptococci strains were resistant to penicillin G. Pre- and post-treatment laboratory tests of renal, hepatic and haematopoietic functions produced no evidence of drug toxicity. The cefadroxil dosage effective in this study is lower than that recommended for currently available oral cephalosporins, which must be given on a four times daily schedule.

Adolescent↗

The treatment of Staphyloccocus aureus infected sore nipples: a randomized comparative study.

Sore, cracked nipples are commonly experienced by breastfeeding mothers. We have previously reported a strong correlation between sore, cracked nipples and S. aureus colonization. A prospective, randomized clinical trial was performed to compare four treatment regimes for S. aureus infected sore nipples. Eighty-four breastfeeding mothers were enrolled in the study. After 5 days to 7 days of treatment, only 8% of mothers showed improvement in the "optimal breastfeeding technique alone" group, 16% improved with topical mupiricin, 29% improved with topical fusidic acid, yet 79% improved with oral antibiotics (p < .0001). Optimal breastfeeding techniques and topical antibiotics ointment failed to heal most infected, sore, cracked nipples. Mastitis developed in 12% to 35% of mothers not treated with systemic antibiotics compared to 5% of mothers treated with systemic antibiotics (p < .005). In conclusion, S. aureus infected sore, cracked nipples should be diagnosed as a potentially widespread impetigo vulgaris and treated aggressively with systemic antibiotics in order to improve healing and decrease the risk of developing mastitis due to an ascending lactiferous duct bacterial infection.

Administration, Cutaneous↗

Topical mupirocin in the treatment of bacterial skin infections.

Mupirocin is an investigational topical antibiotic used for treatment and prophylaxis of bacterial skin infections. Mupirocin differs from other antibiotics in its synthesis, structure, and mechanism of action. In vitro, mupirocin possesses antimicrobial activity against staphylococci, streptococci, Hemophilus influenzae, and Neisseria gonorrhoeae. Few studies comparing mupirocin to other topical antibiotics are available. Initial studies comparing mupirocin to inactive vehicle in the treatment of impetigo indicate an overall 92 percent pathogen eradication rate with active drug and 58 percent eradication rate with vehicle. Overall response to treatment of secondary skin infections was favorable in 91 percent of patients treated with mupirocin and 77 percent of those treated with vehicle. Although incidence is not greater than placebo, adverse effects have included pruritus, burning, dry skin, and erythema. Additional trials and clinical use should further help determine the role of mupirocin in the treatment of minor, primary, and secondary skin infections.

Anti-Bacterial Agents↗