Resistant Streptococcus Pyogenes Research Articles

Molecular Characterization of Multi-drug Resistant Streptococcus pyogenes and Its Eradication Using Essential Oil of Zingiber officinale as a Natural Antimicrobial Agent

Molecular Characterization of Multi-drug Resistant Streptococcus pyogenes and Its Eradication Using Essential Oil of Zingiber officinale as a Natural Antimicrobial Agent

Photodynamic inactivation (effect of laser with and without photosensitizer) on viability of streptococcus pyogenes

Abstract:
 Burns wounds infection is the high most frequent complications of burns as a result of penetration of bacteria from neighboring tissue. Because of expanded utilization of antibiotics, the spread of multi-drug resistance bacteria emerge as one of alarming hazard to public health.
 Photodynamic inactivation is the technique that can be used to prohibit these organisms. This study focused on bactericidal potency of toluidine blue (TBO) photosensitizer and red laser radiation of 635nm with different doses against multi-drug resistant streptococcus pyogenes (S. pyogenes) isolated from infected burns wounds to see if it is susceptible to photodynamic inactivation .
 A total of 45 isolates were collected from 38 patients with infected burns wounds samples were collected from September to December 2019.Burns wounds swabs were employed using standard procedure of swab collection. Among these, eleven isolates were multidrug resistant S.pyogenes. More resistant isolate that has been proved to all antibiotics used. This multidrug resistant isolate used in all experiments. Bacterial suspension was diluted by using serial dilution. The suspension of S. pyogenes in normal saline was treated with red laser radiation at a wavelength 635nm with and without TBO, and investigated the effect of changing laser doses (3.6 ,7 and 10.8 J/cm2) corresponding to laser exposure time (5,10 and 15 minutes and different photosensitizer concentrations on viability of S. pyogenes isolated from infected burns wounds. The results of this study suggest that multi- drug resistance S pyogenes isolated from infected burns wounds inhibited by using photodynamic inactivation mediated by TBO and red laser at a wavelength 635 nm. The effective technique for killing or inhibiting S. pyogenes isolated from infected burns wounds is the combination of red laser at a wave length 635nm and TBO. Combination of TBO and red laser light prohibit S. pyogenes, the optimum results of bacterial inhibition obtained at 50µg/ml, and laser dose 7 J/cm2 corresponding to exposure time 10 minutes.

Neurodegenerative Disease Treatment Drug PBT2 Breaks Intrinsic Polymyxin Resistance in Gram-Positive Bacteria.

Gram-positive bacteria do not produce lipopolysaccharide as a cell wall component. As such, the polymyxin class of antibiotics, which exert bactericidal activity against Gram-negative pathogens, are ineffective against Gram-positive bacteria. The safe-for-human-use hydroxyquinoline analog ionophore PBT2 has been previously shown to break polymyxin resistance in Gram-negative bacteria, independent of the lipopolysaccharide modification pathways that confer polymyxin resistance. Here, in combination with zinc, PBT2 was shown to break intrinsic polymyxin resistance in Streptococcus pyogenes (Group A Streptococcus; GAS), Staphylococcus aureus (including methicillin-resistant S. aureus), and vancomycin-resistant Enterococcus faecium. Using the globally disseminated M1T1 GAS strain 5448 as a proof of principle model, colistin in the presence of PBT2 + zinc was shown to be bactericidal in activity. Any resistance that did arise imposed a substantial fitness cost. PBT2 + zinc dysregulated GAS metal ion homeostasis, notably decreasing the cellular manganese content. Using a murine model of wound infection, PBT2 in combination with zinc and colistin proved an efficacious treatment against streptococcal skin infection. These findings provide a foundation from which to investigate the utility of PBT2 and next-generation polymyxin antibiotics for the treatment of Gram-positive bacterial infections.

Antibiotic Resistant Bacteria Infecting Wounds of Rural Community Dwellers in Northern Ghana

To determine the prevalence, etiology and antibiotic susceptibility profile of bacterial agents of wound infection in rural community dwellers in the Northern region of Ghana. From August 2017 to July 2018, patients who reported with infected wound to four (4) primary health facilities were recruited after obtaining written informed consent. Wound swabs were taken from 93 participants; 59(63.4%) males and 34(36.6%) females. Wounds were aseptically swabbed and cultured. Antibiotic susceptibility tests (AST) were performed on all isolates using agar disc diffusion method according to Clinical and Laboratory Standards Institute CLSI 2013 guidelines. A total of 165 bacteria isolates were obtained from 93 wound swabs. The most predominant bacteria species were Staphylococcus aureus 38(23.0%) followed by Pseudomonas aeruginosa 27(19.7%), and Klebsiella pneumoniae 15(9.1%). Many of the isolates were from burns 61(37.0%) and diabetic wounds 33 (20.0%), with few from motor traffic wounds 5(3.0%). Most of the isolates were resistant to third generation cephalosporins. Notably, all (100%) of the Acinetobacter and Providencia species and 75% of Proteus species were resistant to ceftazidime and ceftriaxone. High resistance to ceftazidime and ceftriaxone was also observed in K. pneumoniae (53.3% and 53.3%) and E. coli (60.0% and 50.0%) respectively. Resistance in Streptococcus pyogenes to penicillin and erythromycin was 60% and 70% respectively while 10.5 % of the Staphylococcus aureus isolates were methicillin resistant (MSRA). This study revealed a wide range of bacterial agents are associated with wound infection and are resistant to commonly used antibiotics. Additionally, the study suggests relatively high antibiotic resistance is associated with community acquired infection of wounds.

Rate and Mechanism of Erythromycin Resistance in Streptococcus pyogenes in Beni-Suef University Hospital

Background: Group A streptococci (GAS) is a major cause of morbidity and mortality. Erythromycin is an effective macrolide antibiotic for treating GAS infections. However, GAS macrolide resistance has been increased due to either an efflux mechanism (M phenotype), encoded by mef A gene, or by methylation of the ribosomal target resulting in resistance to macrolide, lincosamide, and streptogramin B (MLS) antibiotics. Methylase can be expressed either constitutively (cMLS phenotype) or inducibly (iMLS phenotype). Objectives: The present study aimed to find out frequency of S. pyogenes isolated from patients with upper respiratory tract infections at Beni-Suef University Hospital, determine rate and mechanism of macrolide resistance. Methodology: The present study was conducted on patients with upper respiratory tract infections attended to otorhinolaryngology clinic, Beni-Suef University Hospital, Egypt, in the period from February to December 2015. Detailed history taking was carried and clinical findings were obtained. Throat or ear swabs were taken and processed by conventional bacteriological methods. S. pyogenes isolates were further tested to determine erythromycin resistance phenotype by D- test, MIC of Erythromycin by tube broth dilution method and for mef A gene by PCR. Results: Forty two S. pyogenes isolates were identified from (100) swabs taken from either ear or throat specimens (42%), isolates resistance to erythromycin and clindamycin was 83.3% (35) and 31% (13) respectively. The pattern of macrolide resistance was 31% (13/ 42) cMLS phenotype, 52.3% (22/42) M phenotype and no isolate was iMLSB phenotype. Most strains with M phenotype expressed low-level macrolide resistance (MIC 1-4μg/ml), while cMLSB isolates showed a high level of erythromycin resistance (MIC ≥64 μg/ml) (highly significant: p-value 0.0001). The results confirmed a strong correlation between the M phenotype and the mef A gene in GAS (highly significant: p-value =0.001). Conclusion: Incidence of erythromycin resistance was evident among the isolates. To preserve the necessary efficacy, limited use of erythromycin is recommended.

Trend of antibiotic susceptibility of Streptococcus pyogenes isolated from respiratory tract infections in tertiary care hospital in south Karnataka

Streptococcus pyogenes is recognized as an important pathogen of respiratory tract infections. The rapidly, emerging problem of antibiotic resistant Streptococcus pyogenes is a major issue nowadays. The present study aimed to evaluate the antibiotic susceptibility of Streptococcus pyogenes isolated from upper respiratory tract infections in tertiary care hospital of south Karnataka. A retrospective study was conducted over a period of two years. The specimens were processed by Gram staining and aerobic culture. The bacteria were isolated as per standard protocols. The minimum inhibitory values and extent of antibiotic resistance of commonly used antimicrobials were analysed for the isolated strains. A total of 2123 specimens were received from patients with respiratory tract infections, among which, 50 Streptococcus pyogenes isolates were obtained. Out of these, 8% were not sensitive to penicillin. Using VITEK 2 system, the prevalence of resistances to cefotaxime, erythromycin, tetracycline, levofloxacin, clindamycin and ceftriaxone were 4.2%, 83%, 51%, 8.9%, 40% and 5.3% respectively. It is important to know about the prevalence of resistance and rising MIC values of commonly used antibiotics regarding Streptococcus pyogenes to avoid therapeutic failures.

Longitudinal survey of ATB resistance reversibility in children with AIDS of genocide survivors in Cambodia

Background: The aim of the survey was to assess antimicrobial resistance dynamics and reversibility in the group of children with AIDS in Cambodia in 2003 2015. Patients: Correlation between antimicrobial (ATB) resistances in commonest respiratory isolates among 140 children with AIDS on antiretroviral therapy was studied from 2003 to 2015 in 586 isolates. Original Articles 8 Clinical Social Work and Health Intervention Clinical Social Work and Health Intervention Vol. 7 No. 3 2016 Results: All but 3 (98%) children showed a sustained CD4 increase after introduction of antiretroviral therapy (ART) followed by a decrease of ATB resistance. In our group of children restoration of the immune system decreased the number of infection diseases episodes and the proportion of multi-resistant bacterial strains. Conclusions: Less frequent use of antimicrobial therapy probably led to the decrease of multi-resistance and restoration of susceptibility of studied respiratory bacterial isolates. Results and discussion Table 1 presents trends in ATB resistance in major respiratory isolates from October 2003 to December 2015 (total of 586 isolates). Penicillin resistance in pneumococci decreased from 25% to 2% in 2015 (P<0.01); t-test for trends), MRSA from 33.3% in 2003 to 3% in 2014 and 2% in 2015 (P<0.01). Erythromycin resistance in Streptococcus pyogenes decreased from 10.5% in 2003 to 3.3% in 2015. At baseline extremely high proportion of ESBL producing Enterobacteriaceae decreased from 66.6% to 25% and such trend was also observed in Candida species and resistance to fluconazole (from 15% in 2003 to 6% in 2015). Reversibility of ATB resistance was documented on the hospital level (2) or on the community national level (1.3), however only in countries with small population (Finland, Denmark, Iceland) with centralized ATB policy. Reversibility time was 2-5 years per country and more (up to 5 years). Reversibility of susceptibility or antibiotic resistance was not yet sufficiently studied in pediatric population with specific immunodeficiency therefore it is deficient to assess, of 10 15 years in our group is comparable to e.g. 2 5 years on a nation level from Europe (5-8).

Trend of Respiratory Tract-Associated Streptococcus dysgalactiae Subsp. Equisimilius at General Japanese Hospital from 2013 to 2015

Streptococcus dysgalactiae subsp. equisimilius are pathogenic bacteria which cause various infectious diseases from acute pharyngitis to streptococcal toxic shock syndrome. Although Streptococcus dysgalactiae subsp. equisimilius infection has been increasing recently, the recent characteristic investigation of respiratory tract associated Streptococcus dysgalactiae subsp. equisimilius has not been performed in Japan. In this study, we analyzed the relationship between respiratory tract and norespiratory tract associated Streptococcus dysgalactiae subsp. equisimilius by investigating the recent clinical characteristics and antimicrobial susceptible patterns of 98Streptococcus dysgalactiae subsp. equisimilius isolated during 2013-2015 in Japan. There was significant difference of gender between respiratory tract and no respiratory tract associated Streptococcus dysgalactiae subsp. equisimilius. No Streptococcus dysgalactiae subsp. equisimilius from no respiratory tract were found under 18 years-old patients. The prevalence of clindamycin non susceptible Streptococcus dysgalactiae subsp. equisimilius isolates from respiratory tract was significant greater than those from non-respiratory tract. We also analyzed the relationship between respiratory tract associated Streptococcus dysgalactiae subsp. equisimilius and Streptococcus pyogenes in 2014.There was no significant difference of gender between Streptococcus dysgalactiae subsp. equisimilius and Streptococcus pyogenes. The numbers of Streptococcus pyogenes-infected patients were significantly greater than those of Streptococcus dysgalactiae subsp. equisimilius-infected patients in children from 1 to 18 years old. From antimicrobial resistance, we found that the numbers of clarithromycin resistant Streptococcus pyogenes were greater than those of clarithromycin resistant Streptococcus dysgalactiae subsp. equisimilius among respiratory tract isolation. Our results suggest that the clinical and antimicrobial susceptible patterns are useful for screening the respiratory tract associated Streptococcus dysgalactiae subsp. equisimilius infection.

Predominant role of msr(D) over mef(A) in macrolide resistance in Streptococcus pyogenes.

In Japan, the number of patients with streptococcal toxic shock syndrome is reported to be increasing. mef(A) gene-positive macrolide-resistant emm1 strains are thought to possibly contribute to the rise in the frequency of STSS. Although analyses of macrolide-resistant mechanisms, including mef(A) resistance, have been performed mainly in Streptococcus pneumoniae, the role of this gene in Streptococcus pyogenes has not been completely investigated. Therefore, to the best of our knowledge, we established the first mef(A)-knockout strain using an emm1-type S. pyogenes strain, and tested its susceptibility to erythromycin, clarithromycin and azithromycin. We found that the antimicrobial susceptibilities were almost identical to those of the parental strain. Hence, we established a knockout strain for another gene, msr(D), that is located immediately downstream of mef(A). The macrolide resistances of the resulting strain significantly decreased, and were further altered when both mef(A) and msr(D) were knocked out. The introduction of the msr(D) gene into a macrolide-sensitive strain conferred more resistance than the introduction of the mef(A) gene. The erythromycin susceptibilities of knockout strains were further dissected using two additional emm4- and emm75-type S. pyogenes strains. We found almost identical results for both strains except for the mef(A) knockout emm4 type, whose susceptibility was altered, although the change was less than that for the msr(D) knockout. These results suggest that both mef(A) and msr(D) are involved in macrolide resistance in S. pyogenes, and that the msr(D) gene plays a more predominant role in macrolide resistance than mef(A).

Epidemiological study of erythromycin-resistant Streptococcus pyogenes from Korea and Japan by emm genotyping and multilocus sequence typing.

BackgroundWe determined the epidemiological characteristics of erythromycin (EM)-resistant Streptococcus pyogenes (group A streptococci, GAS) strains isolated from Korea and Japan, using emm genotyping and multilocus sequence typing (MLST).MethodsClinical isolates of GAS had been collected from 1992 to 2012 in Korea and from 2004 to 2009 in Japan. EM resistance was determined by the microdilution method, and resistance genotypes were assessed by PCR. The emm genotyping and MLST were performed by DNA sequencing.ResultsThe emm genotypes and sequence types (STs) were concordant in 143 (85.1%) of 168 EM-resistant GAS strains from Korea. ST36/emm12 (35.1%), ST52/emm28 (22.6%), and ST49/emm75 (16.1%) were the most common types. Most of the ST36 (93.9%) and ST52 (95.8%) strains harbored erm(B), whereas strains ST49, ST42, and ST15 contained mef(A). The concordance between emm genotypes and STs was 41 (93.2%) among 44 EM-resistant GAS strains from Japan. ST36/emm12 (34.1%), ST49/emm75 (18.2%), and ST28/emm1 (15.9%) were the major types. ST36 isolates harbored either erm(B) (56.3%) or mef(A) (37.5%), whereas isolates ST28, ST49, and ST38 carried only mef(A). The proportion of erm(B) and mef(A) was 66.1% and 33.3% in Korea and 22.7% and 68.2% in Japan, respectively.ConclusionsThe common STs in Korea and Japan were ST36 and ST49, whereas ST52 was present only in Korea and ST28 only in Japan. Genotype erm(B) was predominant in Korea, whereas mef(A) was frequent in Japan. There were differences between Korea and Japan regarding the frequencies of emm genotypes, STs, and EM resistance genes among the EM-resistant GAS.

Synthesis and structure–activity relationships of novel 9-oxime acylides with improved bactericidal activity

9-Oxime acylides have different SAR and binding modes from 9-oxime ketolides. An aminopyridyl or carbamoylpyridyl group anchored at the end of the 9-oxime 2-propargyl group is beneficial for antimicrobial activity. Both the 2-pyridyl and 3-pyridyl groups derived from 3-OH have stacking interactions with the base pair G2505/C2610 (Escherichia coli numbering) of the bacterial rRNA. Compounds 3 presented characteristic features that belong to bactericidal agents when used against constitutive-erm resistant Staphylococcus aureus, susceptible and mef-encoded Streptococcus pneumoniae, inducible-erm resistant Streptococcus pyogenes, and Moraxella catarrhalis. A docking model indicated that the carbamoylpyridyl group of 3h may hydrogen bond to G2061 in addition to π–π stacking over the adenine of A2062 that proved to gate the tunnel for the egress of the nascent peptide. This study suggests that the 9-oxime acylides possess a bactericidal mechanism that is different from the traditional near-complete inhibition of protein synthesis. These studies provide a foundation for the rational design of macrolide antibiotics.

Correlation between genetic features of the mef(A)-msr(D) locus and erythromycin resistance in Streptococcus pyogenes

We investigated the correlation between the genetic variation within mef(A)-msr(D) determinants of efflux-mediated erythromycin resistance in Streptococcus pyogenes and the level of erythromycin resistance. Twenty-eight mef(A)-positive strains were selected according to erythromycin MIC (4–32μg/mL), and their mef(A)-msr(D) regions were sequenced. Strains were classified according to the bacteriophage carrying mef(A)-msr(D). A new Φm46.1 genetic variant was found in 8 strains out of 28 and named VP_00501.1. Degree of allelic variation was higher in mef(A) than in msr(D). Hotspots for recombination were mapped within the locus that could have shaped the apparent mosaic structure of the region. There was a general correlation between mef(A)-msr(D) sequence and erythromycin resistance level. However, lysogenic conversion of susceptible strains by mef(A)-msr(D)–carrying Φm46.1 indicated that key determinants may not all reside within the mef(A)-msr(D) locus and that horizontal gene transfer could contribute to changes in the level of antibiotic resistance in S. pyogenes.

Evolution of macrolide resistance in Streptococcus pyogenes over 14 years in an area of central Italy

We evaluated temporal fluctuations in macrolide resistance rates, analysing genetic determinants of resistance and clonal evolution in a population of 2744 S. pyogenes isolates collected in the period 2000-2013. The total resistance rate to erythromycin of the isolates was 17.9 %. A maximum of erythromycin resistance emerged in 2000 (38.6 %), followed by a significant decrease to 5.2 % in 2012 (P < 0.0001). Molecular analysis revealed the presence and co-presence of known genetic resistance determinants mefA, mefE, ermTR and ermB, in line with phenotypes. PFGE analysis identified genetically related groups in 2000 and 2007-2008, mainly the MLS and M phenotypes, respectively. The most prevalent emm types among a representative subset of resistant isolates were emm2, emm75 and emm77. All emm2 and 88.2 % of the strains harbouring the emm75 gene were only recorded in M-phenotype strains, whilst all emm77-positive strains had the inducible MLS phenotype. The analysed susceptible isolates showed several emm types partially shared with resistant ones. Our results suggest that changes in bacterial population clonality, rather than horizontal transfer of resistance determinants, plays a major epidemiological role in S. pyogenes. Continuous monitoring of microbiological epidemiology seems to be crucial for correct and effective management of streptococcal infections.

Molecular characterization of macrolide resistant Streptococcus pyogenes isolates from pharyngitis patients in Serbia

A steady increase in macrolide resistance in Streptococcus pyogenes, group A streptococci (GAS) was reported in Serbia during 2004–2009 (9.9%). However, there are no data on the molecular epidemiology of pharyngeal macrolide resistance GAS (MRGAS) isolates. Therefore, the aims of this first nationwide study were to examine the prevalence of macrolide resistance in Serbian GAS and to determine their resistance phenotypes, genotypes and clonal relationships. Overall 3893 non-duplicate pharyngeal S. pyogenes isolates from outpatients with GAS infection were collected throughout country during 2008 and 2009. Among 486 macrolide resistant pharyngeal isolates collected, 103 were further characterized. Macrolide resistance phenotypes and genotypes were determined by double-disk diffusion test and PCR, respectively. Strain relatedness was determined by emm typing, multilocus sequence typing (MLST), multilocus variable tandem repeat analysis (MLVA), phage profiling (PP) and virulence factor profiling (VFP). Overall, macrolide resistance among GAS isolates in Serbia was 12.5%. M phenotype was the most common (71.8%), followed by iMLS (18.4%) and cMLS (9.7%). Three clonal complexes – emm75/mefA/ST49, emm12/mefA/ST36 and emm77/ermA/tetO/ST63 comprised over 90% of the tested strains. Although MLVA, PP and VFP distinguished 10, 20 and 12 different patterns, respectively, cluster analysis disclosed only small differences between strains which belonged to the same emm/ST type. Our data indicate dominance of three major internationally widely disseminated macrolide resistant clones and a high genetic homogeneity among the Serbian MRGAS population. Continued surveillance of macrolide resistance and clonal composition in MRGAS in Serbia in future is necessary to determine stability of MRGAS clones and to guide therapy strategies.

Clindamycin resistant emm33 Streptococcus pyogenes emerged among invasive infections in Helsinki metropolitan area, Finland, 2012 to 2013.

In 2012, blood, skin and soft tissue infections caused by clindamycin resistant Streptococcus pyogenes (group A streptococcus; GAS) appeared to be increasing in the Helsinki metropolitan area. We compared monthly percentages of clindamycin resistant isolates in the area between 2012 and 2013, with those in 2010 and 2011. Resistance frequency in terms of patient age was also studied. We reviewed the medical records of bacteraemic cases in 2012 and 2013 and linked the data to emm types. To inform on the emm distribution among GAS isolated from skin and soft tissue infections during the epidemic, GAS isolates of one month (March 2013) were emm typed. For GAS blood, skin, and soft tissue isolates taken together, the proportions of clindamycin resistant isolates were significantly higher in 2012 and 2013 (23% and 17%, respectively) compared with the two previous years (3%, p<0,001). The erythromycin resistance percentages were almost equal to clindamycin (22% and 17%) in 2012 and 2013, respectively. Clindamycin resistance was most frequent in GAS isolates of 40 to 60 year-old patients (148/417; 36%). Among clindamycin resistant isolates, 12 of 14 blood isolates from 2012 to 2013, and 11 of 13 skin and soft tissue isolates from March 2013, were emm33. Emm33 GAS bacteraemia was associated with clindamycin and erythromycin resistance (odds ratio (OR): 7.0; 95% confidence interval (CI): 1.9-25.3). Infection focus was mainly the skin; either cellulitis (7/12) or necrotising fasciitis (3/12). All emm33 GAS isolates harboured the ermTR resistance gene with constitutive macrolides, lincosamides and streptogramines B (MLS(B)) phenotype. Emm33 GAS was responsible for the higher proportion of clindamycin resistance in skin, soft tissue, and blood isolates locally in 2012 and 2013.

Molecular Modeling on Streptolysin-O of Multidrug Resistant Streptococcus pyogenes and Computer Aided Screening and In Vitro Assay for Novel Herbal Inhibitors

Streptococcus pyogenes is a notorious pathogenic bacterium which causes various human diseases ranging from localized infections to life threatening invasive diseases. Streptolysin-O (SLO), pore-forming thiol-activated cytolysin, is the major virulent factor for streptococcal infections. Present therapies against streptococcal infections are limited as most of the strains have developed multi-drug resistance to present generation of drugs. Hence, there is a need for alternative therapeutic substances. Structure based virtual screening is a novel platform to select lead molecules with better pharmacokinetic properties. The 3D structure of SLO (not available in native form), essential for such studies, was computationally generated and this homology model was used as probable drug target. Based on literature survey, several phytoligands from 25 medicinal plants were selected. Out of these, leads from 11 plants showed better pharmacokinetic properties. The best lead molecules were screened based on computer aided drug likeness and pharmacokinetic predictions. The inhibitory properties of selected herbal leads against SLO were studied by molecular docking. An in vitro assay was further carried out and variations observed were found to be significant (p<0.05). Antibiotic sensitivity testing was also performed with the clinical strain of Streptococcus pyogenes with conventional drugs. The clinical strain showed multi-drug resistance to conventional drugs. Our study revealed that numerous phytoligands have better inhibitory properties towards the toxin. We noticed that incorporation of selected herbal extracts in blood agar medium showed significant reduction in hemolysis (MIC 300μl/plate), indicating inhibition of SLO. Furthermore, the butanol extracts of selected herbal preparation based on computer aided screening showed significant inhibitory properties at 250 mcg/disc concentration. We also noticed that selected herbal formulations have better antimicrobial properties at MIC range of 300- 400μl. Hence, our study suggests that these herbal extracts have better inhibitory properties against the toxin as well as drug resistant Streptococcus pyogenes.

What causes decreased erythromycin resistance in Streptococcus pyogenes? Dynamics of four clones in a southern European region from 2005 to 2012

To survey antibiotic resistance among Streptococcus pyogenes isolates collected from 2005 to 2012, to characterize those showing erythromycin resistance and to analyse the association of certain emm types with erythromycin resistance or susceptibility. Resistance determinants or mutations conferring erythromycin, clindamycin, tetracycline and fluoroquinolone resistance were analysed. All erythromycin-resistant isolates and a sample of erythromycin-susceptible isolates were emm typed. Multilocus sequence typing was performed for representative emm types. Antimicrobial susceptibility was studied for 12 346 S. pyogenes isolates. Erythromycin, clindamycin and tetracycline resistance showed a decreasing trend. In 2012, 2.8% of isolates were erythromycin resistant versus 7.5% in 2005 and 11.7% in 2006. Although 21 clones were involved, 4 clones accounted for almost 90% of erythromycin-resistant isolates. The emm12/ST36 clone, carrying the mef(A) gene, was the predominant (41.1%) erythromycin-resistant clone, with an incidence peak in 2008, followed by a gradual decline. The M phenotype predominated each year except for 2005, when two of the main erythromycin-resistant clones (emm11/ST403 and emm28/ST52) harboured an erm(B) gene. Erythromycin resistance was significantly higher in adults than in children. Skin isolates showed the highest erythromycin resistance rate; among these, perianal isolates frequently belonged to the emm28/ST52 clone. The emm type was not a predictor of erythromycin resistance; however, most emm11 and emm12 were erythromycin-resistant isolates. Macrolide consumption was similar throughout the study period. Only two isolates with a high level of levofloxacin resistance were detected. Resistance was mainly related to the circulation of emm12/ST36, emm11/ST403, emm28/ST52 and emm4/ST39 clones, all of which declined throughout the study period.

ICE Sp1116 , the Genetic Element Responsible for erm (B)-Mediated, Inducible Erythromycin Resistance in Streptococcus pyogenes, Belongs to the Tn GBS Family of Integrative and Conjugative Elements

While most integrative and conjugative elements (ICEs) encode Tyr/Ser recombinases, two ICE families have recently been described ([1][1]) that rely on DDE transposases ([2][2]) for circularization and integration into the chromosome. Such ICE families, described in Streptococcus agalactiae (Tn GBS

ICE Sp1116 , the Genetic Element Responsible for erm (B)-Mediated, Inducible Resistance to Erythromycin in Streptococcus pyogenes

ICESp1116, responsible for erm(B)-mediated, inducible erythromycin resistance in Streptococcus pyogenes, was comprehensively characterized, and its chromosomal integration site was determined. It displayed a unique mosaic organization consisting of a scaffold, related to TnGallo1 from Streptococcus gallolyticus, with two inserted fragments separated by IS1216. One fragment, containing erm(B), displayed high-level identity to a portion of the S. pyogenes plasmid pSM19035; the other, containing a truncated tet(M) gene, displayed high-level identity to the right-hand portion of Clostridium difficile Tn5397.

Análisis de los fenotipos y genotipos de resistencia a eritromicina y clindamicina en cepas de Streptococcus pyogenes aisladas en Chile en un período de 10 años

Macrolide and lincosamide resistance in Streptococcus pyogenes is due to the acquisition of mef, ermB and ermA genes, which confer different resistance phenotypes, namely M, MLSBconstitutive and MLSBinducible respectively. The last report of resistance in Chile was done in the period 1990-1998, in which resistance to macrolides was 5.4%, with M phenotype as the predominant one.To characterize the evolution of erythromycin and clindamycin resistance and their associated genes in S. pyogenes strains isolated from patients with invasive and non-invasive infections in the period 1996 to 2005.Resistance to erythromycin and clindamycin was determined in 1,282 clinical isolates using the disk diffusion test. Resistant isolates were analyzed by polymerase chain reaction (PCR) for the presence of the above mentioned resistance genes.Global resistance to erythromycin and clindamycin was 3.5 and 0.7% respectively. Eighty percent of the resistant strains possessed the M. phenotype.Resistance levels of S. pyogenes have decreased in Chile in the last years. Most resistant strains have M phenotype in contrast to many countries in which the MLSB constitutive phenotype is the predominant one.