Macrolide and tetracycline resistance and emm type distribution of Streptococcus pyogenes isolates recovered from Turkish patients

Distribution of emm, superantigen and other virulence genotypes and detection of phylogenetic relationships in group A streptococcal isolates

Group A streptococci are important pathogens with various virulence factors, such as M protein, superantigens, hemolysins, deoxyribonuclease, and proteases. The aims of this study are to investigate the detection of emm genotypes and other virulence genes, such as SAgs, DNase, protease, antibiotic resistance, and phylogenetic relationships in GAS strains isolated from clinical samples.Test strains were obtained from Çukurova University Balcalı Hospital and regional hospitals in Adana province. The M proteins were detected by sequence analysis of emm genes. SAgs and other virulence gene profiles were determined using the Multiplex-PCR method. The antibiotic susceptibility of the isolates was performed by the disc diffusion method and evaluated according to CLSI criteria. The PFGE method was used to determine the clonal relationship between the strains.The emm gene was positive in 86 isolates. The most common emm genotypes were emm28 (22%), emm1 (18.6%), emm12 (13.9%), and emm3 (11.6%). Also, the most common virulence genes were speG (58.1%), speC (56.9%), sdaB (53.4%), and mac (53.4%). The rates of resistance to erythromycin, clindamycin, levofloxacin, ciprofloxacin and telithromycin were 19.8%, 16.3%, 4.7%, 3.5%, and 3.5%, respectively.As a result, additional regional studies on the detection and prevalence of GAS virulence factors in Turkey are required. We believe that this study will provide valuable information for epidemiological studies on emm sequences, Sags, and other virulence factors of Streptococcus pyogenes in Turkey.

A global snapshot on the prevalent macrolide-resistant emm types of Group A Streptococcus worldwide, their phenotypes and their resistance marker genotypes during the last two decades: A systematic review

Watchful epidemiological surveillance of macrolide-resistant Group A Streptococcus (MRGAS) clones is important owing to the evolutionary and epidemiological dynamic of GAS. Meanwhile, data on the global distribution of MRGAS emm types according to macrolide resistance phenotypes and genotypes are scant and need to be updated. For this, the present systematic review analyses a global set of extensively characterized MRGAS isolates from patients of diverse ages and clinical presentations over approximately two decades (2000 to 2020) and recaps the peculiar epidemiological features of the dominant MRGAS clones. Based on the inclusion and exclusion criteria, 53 articles (3593 macrolide-resistant and 15,951 susceptible isolates) distributed over 23 countries were dissected with a predominance of high-income countries over low-income ones. Although macrolide resistance in GAS is highly variable in different countries, its within-GAS distribution seems not to be random. emm pattern E, 13 major emm types (emm12, 4, 28, 77, 75, 11, 22, 92, 58, 60, 94, 63, 114) and 4 emm clusters (A-C4, E1, E6, and E2) were significantly associated with macrolide resistance. emm patterns A-C and D, 14 major emm types (emm89, 3, 6, 2, 44, 82, 87, 118, 5, 49, 81, 59, 227, 78) and 3 well-defined emm clusters (A-C5, E3, and D4) were significantly associated with macrolide susceptibility. Scrutinizing the tendency of each MRGAS emm type to be significantly associated with specific macrolide resistance phenotype or genotype, interesting vignettes are also unveiled. The 30-valent vaccine covers ~95% of MRGAS isolates. The presented data urge the importance of comprehensive nationwide sustained surveillance of MRGAS circulating clones particularly in Low and Middle income countries where sampling bias is high and GAS epidemiology is obfuscated and needs to be demystified.

Distribution of emm types and macrolide resistance determinants among group A streptococci in the Middle East and North Africa region

OBJECTIVES

The aim of this review was to provide an updated scenario on the epidemiology of group A streptococci (GAS) in the Middle East and North Africa (MENA) region with a special spotlight on the most prevalent emmtypes and macrolide resistance profiles.

METHODS

This review briefly summarises the disease burden for GAS in the MENA region.

RESULTS

Whilst the burden of invasive GAS infections is difficult to assess in the MENA region, the GAS prevalence ranged from 2.5% up to 42.4% in pharyngitis patients and from 2.4% up to 35.4% in healthy carriers.emm1, emm12, emm89, emm4, emm28 and emm3were responsible for the major GAS burden in the MENA region. The coverage rate of the new M protein-based vaccine candidate (30-valent) varied from 42% to 100% according to the country. The rate of erythromycin resistance differed substantially between countries from low to moderate or high.

CONCLUSION

These data add more shreds of evidence on the neglected GAS burden in the MENA region. Systematic surveillance of invasive GAS infections along with molecular characterisation of GAS isolates are strongly recommended to track the trends of circulating clones and to evaluate the potential coverage of vaccine candidates.

Characterization of Streptococcus pyogenes from Animal Clinical Specimens, Spain

Streptococcus pyogenes appears to be almost exclusively restricted to humans, with few reports on isolation from animals. We provide a detailed characterization (emm typing, pulsed-field gel electrophoresis [PFGE], and multilocus sequence typing [MLST]) of 15 S. pyogenes isolates from animals associated with different clinical backgrounds. We also investigated erythromycin resistance mechanisms and phenotypes and virulence genes. We observed 2 emm types: emm12 (11 isolates) and emm77 (4 isolates). Similarly, we observed 2 genetic linages, sequence type (ST) 26 and ST63. Most isolates exhibited the M macrolide resistance phenotype and the mefA/ermB genotype. Isolates were grouped into 2 clones on the basis of emm-MLST-PFGE-virulence gene profile combinations: clone 1, characterized by the combined genotype emm12-ST36-pulsotype A-speG; and clone 2, characterized by the genotype emm77-ST63-pulsotype B-speC. Our results do not show conclusively that animals may represent a new reservoir of S. pyogenes but indicate the ability of human-derived S. pyogenes isolates to colonize and infect animals.

Distribution of macrolide resistance mechanisms in Bulgarian clinical isolates of Streptococcus pyogenes during the years of 2013-2016

Streptococcus pyogenes, or group A streptococcus (GAS), is the main etiological agent of bacterial tonsillopharyngitis and a common cause of a wide variety of other mild to severe infections.

OBJECTIVES

Objectives of the present study was to determine and evaluate the distribution of genetic mechanisms associated with certain phenotypes of macrolide resistance in Bulgarian GAS isolated during the years of 2013-2016.

METHODS

All GAS strains were screened for the macrolide resistance genes erm(A), erm(B) and mef(A), using multiplex polymerase chain reaction (PCR). The minimal inhibitory concentrations (MICs) of erythromycin, azithromycin, clarithromycin, clindamycin were determined by E-tests.

RESULTS

Almost 23% of GAS isolates obtained in 2013-2014 and near 40% of them in 2015-2016 contained various elements of resistance. The predominant gene was mef(A), which encodes an efflux pump (M-phenotype), identified in 57.84% of the macrolide-resistant strains. The next frequently prevalent mechanism was a combination of mef(A) and erm(B) in 22.55%, which determined high-level inducible or constitutive resistance to macrolides, lincosamides and streptogramins (iMLSB or cMLSB). The highest MIC value (>256mg/L) was detected in association with erm(B) (p<0.05). The MIC range was observed to be much higher in the isolates with combinations of resistance genes vs. those with mef genes alone (p<0.05).

CONCLUSION

The data about the distribution and prevalence of macrolide resistance mechanisms obtained in this study can help in the treatment of persistent and recurrent GAS infections and in the correct choice of empiric therapy.

Incidence of macrolide-lincosamide-streptogramin B resistance amongst beta-haemolytic streptococci in The Gambia

Background

In West Africa, penicillin, macrolide and lincosamide resistance among beta-haemolytic streptococci (BHS) isolates has rarely been described. However, such data are critical to detect and track the emergence of antibiotic resistance.

Methods

Beta-haemolytic streptococci were cultured from clinical specimens from patients attending the clinic at the Medical Research Council Unit The Gambia (n = 217) and kept at −70 °C. Of these, 186 were revived and tested for penicillin susceptibility by disc diffusion and E-test methods, and the D-test for determination of constitutive and inducible macrolide–lincosamide (MLS_B) resistance phenotypes.

Results

The majority of BHS isolates from infections were group A streptococci (GAS) (126/186, 67.7%). Of these, 16% were from invasive disease (30/186). Other BHS isolated included lancefield groups B (19, 10.2%); C (9/186, 4.8%), D (3/186, 1.6%), F (5/186, 2.7%), G (16/186, 8.6%) and non-typeable (8/186, 4.3%). Prevalence of BHS isolated from blood cultures ranges from 0% (2005) to 0.5% (2010). Most (85, 45.7%) of the isolates were from wound infections. Of the 186 BHS isolates, none was resistant to penicillin and 14 (6.1%) were resistant to erythromycin. Of these, 8 (4.3%) demonstrated constitutive MLS_B resistance, and 5 (2.7%) were inducible MLS_B resistant. All the inducible MLS_B isolates were GAS, and majority of the constitutive MLS_B isolates (6/8, 75.0%) were non-GAS.

Conclusions

Beta-haemolytic streptococci, predominantly GAS are associated with a wide range of infections in The Gambia. It is reassuring that macrolide and lincosamide resistance is relatively low. However, monitoring of MLS_B resistance is necessary with the global spread of resistant BHS strains.

Results from the Survey of Antibiotic Resistance (SOAR) 2011-13 in Turkey

OBJECTIVES

Data are presented from the Survey of Antibiotic Resistance (SOAR) for respiratory tract infection pathogens collected in 2011-13 from Turkey.

METHODS

MICs were determined using Etest(®). Susceptibility was assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) interpretive criteria.

RESULTS

Rates of antibiotic susceptibility were very low among 333 isolates of Streptococcus pneumoniae tested: penicillin 38% using CLSI (oral) and EUCAST breakpoints; erythromycin 51% using CLSI and EUCAST criteria; and cefuroxime 64.6% using CLSI and PK/PD and 46.9% using EUCAST. Of the isolates, >90% were susceptible to amoxicillin/clavulanic acid, ceftriaxone (except using EUCAST criteria: 76%), levofloxacin and high-dose intravenous penicillin. Among 339 Haemophilus influenzae isolates, 6.8% were β-lactamase positive while 9.1% were β-lactamase negative but ampicillin resistant (BLNAR) by CLSI (14.7% by EUCAST) criteria. Amoxicillin/clavulanic acid susceptibility was ∼90% by CLSI (with or without BLNAR adjustment, EUCAST and high-dose PK/PD) but lower, at 82.9%, by EUCAST with BLNAR adjustment. Levofloxacin susceptibility was 96% using all three breakpoints. Dramatic differences in rates of susceptibility, depending on the breakpoints used, were seen for cefaclor [94% by CLSI (86.4% BLNAR adjusted), 23% by PK/PD] and cefuroxime [97% by CLSI (89.1% BLNAR adjusted), 85% by PK/PD, 15% by EUCAST (13.0% BLNAR adjusted)]. Streptococcus pyogenes (n = 222) and Moraxella catarrhalis (n = 40) isolates remained highly susceptible to amoxicillin/clavulanic acid, cephalosporins and levofloxacin, with only erythromycin susceptibility dropping below 95% for S. pyogenes.

CONCLUSIONS

Overall, amoxicillin/clavulanic acid and levofloxacin were the most active antibiotics based on all three breakpoints against these pathogens. Although susceptibility was not universally low in Turkey, high resistance rates were found in S. pneumoniae and, when using PK/PD and EUCAST breakpoints, in other respiratory pathogens.

Decreased Susceptibility to Azithromycin Among Clinical Shigella Isolates from China

The aim of this study was to detect the decreased susceptibility to azithromycin (DSA) and associated mechanisms in Shigella from China. Three hundred and ninety-two Shigella isolates, including 134 Shigella flexneri and 258 Shigella sonnei isolates, were examined for minimum inhibitory concentrations (MICs) and zone sizes to azithromycin by broth microdilution and disk diffusion methods, respectively. The MICs were compared with corresponding zone diameters to find whether there was uniformity between both tests. Twelve macrolide-resistant genes located on mobile elements were determined for the DSA isolates by PCR, and chromosomal efflux pump activity was analyzed using Phe-Arg-β-naphthylamide inhibition test and quantitative real-time PCR. Shigella isolates displayed MICs of 0.125-512 μg/ml and zone sizes of 6-26 mm against azithromycin. There were 80 (20.4%) isolates to be DSA. No significant difference was found between the DSA rates of S. flexneri and S. sonnei isolates (p = 0.052). There was an intimate relativity between MICs and zone diameters (p < 0.001). Only the plasmid-borne mphA conferring high-level DSA was detected in 55.0% (44/80) DSA-Shigella isolates. This study highlighted the prevalence of DSA-Shigella and mphA in the region studied. Clinical laboratories and clinicians should pay attention to the elevated azithromycin MICs in Shigella spp.

Microbiological Features of Upper Respiratory Tract Infections in Bulgarian Children for the Period 1998-2014

BACKGROUND

Across the globe, upper respiratory tract infections (URTIs) are the most prevalent cause of morbidity in childhood.

AIMS

The aim of our study is to analyze the incidence and etiology of bacterial URTIs in Bulgarian children, as well as the increasing antimicrobial resistance to the most common etiologic agents over a period of 17 years.

STUDY DESIGN

Retrospective study.

METHODS

The study material comprised the data from 4768 patients (aged 1-16 years) with URTI during the period from 1998-2014. Specific microbiology agent detection was performed by culture examination. Susceptibilities to the investigated pathogens were determined by the disk diffusion method and minimal inhibitory concentration according to the criteria of the Clinical and Laboratory Standards Institute (CLSI). Polymerase chain reaction was used to detect the presence of β-lactam resistance genes.

RESULTS

We identified the following as the most common URTI bacterial pathogens: Streptococcus pneumoniae (40.94%), Streptococcus pyogenes (34.16%), Haemophilus influenzae (44.23%), Moraxella catarrhalis (39.19%) and Staphylococcus aureus (23.88%). In more than 70% of cases, a polymicrobial etiology was found. The most commonly affected individuals were pre-school-aged children, which accounted for more than 36% of all patients. During the study period, a dramatic increase in resistance to antibiotic agents was observed. The most frequent types of resistance were the enzymatic inactivation of penicillins and cephalosporins (close to 100% in staphylococci and moraxellae) and inducible macrolide-lincozamide resistance (about 20% of Gram-positive cocci).

CONCLUSION

Due to mandatory immunization against pneumococci and H. influenzae in Bulgaria and the vast expanding resistance to the most popular antimicrobial agents changes in the etiology of URTI have recently been noted. Regular analysis of this etiological dynamic and the antimicrobial resistance of respiratory pathogens is important for choosing the correct therapy and successful treatment.

Susceptibility of Group A Streptococcus to Antimicrobial Agents in Northern Israel: A Surveillance Study

BACKGROUND

Resistant pathogens are an increasing threat affecting millions of people globally. More complicated patients are presented with pathogens harboring new resistance mechanisms, while the pipeline of new antimicrobials hardly proposes solutions. In such a scenario, more severely ill patients remain with no adequate treatment to offer. In addition, massive misuse of antimicrobials, including excessive length of treatment or wrong dosage, also contributes to increasing the rate of pathogens resistance to antimicrobials. Isolation of Streptococcus pyogenes (Group A Streptococcus-GAS) is the main indication for antibiotic treatment to patients diagnosed with acute tonsillitis. Hence, GAS resistance to antibiotics requires periodic monitoring.

OBJECTIVES

To assess susceptibility rates of GAS to penicillin, macrolides, clindamycin, and tetracycline in northern Israel and to compare the findings to the high antimicrobial susceptibility of GAS isolates reported in the same region in 2004 and to other geographical areas.

METHODS

Throat samples from 300 outpatients were collected and cultured at the regional laboratory of Emek Medical Center during September to October 2011.

RESULTS

In 300 samples, the susceptibility rates of GAS to penicillin, erythromycin, azithromycin, clindamycin, and tetracycline in northern Israel still remain very high.

CONCLUSIONS

Continuous control of antimicrobials usage and periodic surveillance of susceptibility rates, together with educational programs and appropriate and targeted treatment protocols, are essential and highly recommended to keep these high susceptibility rates for as long as possible.

ICESp2905, the erm(TR)-tet(O) element of Streptococcus pyogenes, is formed by two independent integrative and conjugative elements

In ICESp2905, a widespread erm(TR)- and tet(O)-carrying genetic element of Streptococcus pyogenes, the two resistance determinants are contained in separate fragments inserted into a scaffold of clostridial origin. ICESp2905 (∼65.6 kb) was transferable not only in its regular form but also in a defective form lacking the erm(TR) fragment (ICESp2906, ∼53.0 kb). The erm(TR) fragment was also an independent integrative and conjugative element (ICE) (ICESp2907, ∼12.6 kb). ICESp2905 thus results from one ICE (ICESp2907) being integrated into another (ICESp2906).