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PubMed1997

An intracellular sanctuary for Streptococcus pyogenes in human tonsillar epithelium--studies of asymptomatic carriers and in vitro cultured biopsies.

A novel method for the in vitro culture of tissue biopsies is presented. Infected tonsillar biopsies were successfully cultured by means of the continuous flow of media without the addition of antibiotics. Histological and immunohistological examinations were carried out on sections of Streptococcus pyogenes-infected cultured tonsillar biopsies and sections from the surgically removed tonsils of asymptomatic S. pyogenes carriers. Low numbers of intracellular S. pyogenes were detected inside epithelial cells in eight out of 12 (67%) S. pyogenes-infected biopsies, and in four out of 11 (36%) tonsils of asymptomatic carriers. Our findings support the hypothesis that the sanctuary where S. pyogenes avoids antibacterial treatment is intracellular, which may provide a possible explanation of recurrent tonsillitis.

Adolescent↗
PubMed2001

Genetic and phenotypic features of Streptococcus pyogenes strains isolated in Brazil that harbor new emm sequences.

In the present study, 37 group A Streptococcus (GAS) strains belonging to 13 new emm sequence types identified among GAS strains randomly isolated in Brazil were characterized by using phenotypic and genotypic methods. The new types were designated st204, st211, st213, st809, st833, st854, st2904, st2911, st2917, st2926, st3757, st3765, and st6735. All isolates were susceptible to the antimicrobial agents tested, except to tetracycline. They all carried the speB gene, and 94.6% produced detectable SpeB. Most strains belonging to a given emm type had similar or highly related pulsed-field gel electrophoresis profiles that were distinct from profiles of strains of another type. The other characteristics were variable from isolate to isolate, although some associations were consistently found within some emm types. Unlike the other isolates, all type st213 isolates were speA positive and produced SpeA. Strains belonging to st3765 were T6 and opacity factor (OF) negative. Individual isolates within OF-positive emm types were associated with unique sof gene sequence types, while OF-negative isolates were sof negative by PCR. This report provides information on new emm sequence types first detected in GAS isolates from a geographic area not extensively surveyed. Such data can contribute to a better understanding of the local and global dynamics of GAS populations and of the epidemiological aspects of GAS infections occurring in tropical regions.

Antigens, Bacterial↗
PubMed1998

Comparison of four antibiotics in a murine model of necrotizing cutaneous infections caused by toxigenic Streptococcus pyogenes and Staphylococcus aureus.

The ability of azithromycin, erythromycin, clarithromycin, or cefuroxime to modify the course of group A streptococcus (GAS) or Staphylococcus aureus soft-tissue infection was compared in a mouse model. In GAS-infected mice given azithromycin, fewer demonstrated dermonecrosis (P = 0.0004); the average weight gain was greater (P < 0.05) and the latency to sustained weight gain was shorter (P < 0.05) than for animals given other antibiotics. All antibiotics were effective against S. aureus infections, with no significant differences among treatments in parameters evaluated. The effectiveness of azithromycin in GAS-infected mice may be related to the high and sustained tissue concentrations achieved with this antibiotic.

Analysis of Variance↗
PubMed1964

A NEW SELECTIVE BLOOD AGAR MEDIUM FOR STREPTOCOCCUS PYOGENES AND OTHER HAEMOLYTIC STREPTOCOCCI.

Horse blood agar containing polymyxin B sulphate, neomycin sulphate, and fusidic acid inhibited the growth of Staph. aureus, Ps. pyocyanea, Proteus mirabilis, E. coli, and Klebsiella pneumoniae but allowed good growth of, and haemolysis by, Str. pyogenes. In a comparison with blood agar, blood 4% agar, and gentian violet blood agar, the selective medium (P.N.F.) yielded a significantly higher proportion of streptococci than the other media, both by aerobic and by anaerobic culture, from burn swab extracts deliberately contaminated with Str. pyogenes; P.N.F. culture was more effective with dilute than with heavy inocula of Str. pyogenes, allowing from three to seven times as many recoveries of Str. pyogenes from swabs contaminated with 10(-3) dilution of streptococcal cultures than cultures of the same material on the other media. Haemolytic streptococci of groups A, C, D, G, and others were isolated by aerobic culture from burns in a consecutive series of 1,277 swabs more often on P.N.F. medium than on blood 4% agar. Viable counts of 12 strains (including 11 different serological types) of Str. pyogenes showed some reduction in the numbers of colonies compared with counts on blood agar, and some strains grew more slowly on P.N.F. medium. These limitations, however, were offset and outweighed by the higher final yield of streptococci on the selective medium.

Agar↗
PubMed2004

Antibiotic selection pressure and resistance in Streptococcus pneumoniae and Streptococcus pyogenes.

We correlated outpatient antibiotic use with prevalence of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP), macrolide-resistant S. pneumoniae (MRSP), and macrolide-resistant S. pyogenes (MRGAS) in 20 countries. Total antibiotic use was correlated with PNSP (r = 0.75; p < 0.001), as was macrolide use with MRSP (r = 0.88; p < 0.001) and MRGAS (r = 0.71; p = 0.004). Streptococcal resistance is directly associated with antibiotic selection pressure on a national level.

Anti-Bacterial Agents↗