Unusual occurrence of M type 77, antibiotic-resistant group A streptococci in southern Sweden.
For many years group A streptococci of T type 28 (T28) have been common in southern Sweden; however, since 1995 resistance to both macrolide-lincosamide-streptogramin B (MLS) antibiotics and tetracycline was observed among T28 isolates, which prompted the present studies on clonal relatedness of antibiotic-resistant T28 strains. By extended T typing, 95 of 100 examined tetracycline-resistant strains showed the combination T9-T13-T28; of these, 94 belonged to M type 77 (M77) and one belonged to M73. Three strains were T28-M28 and two were T28-M nontypeable. The serological M77 was confirmed by PCR capture enzyme-linked immunosorbent assay, emm amplicon restriction profiling, and emm sequence typing. Fifty strains were examined for superantigen genes: speA was detected in three blood isolates only, whereas all isolates harbored speB, and only two of the strains were negative for speC. Eighty-nine of the 100 strains were also macrolide resistant, of which 59 were inducibly MLS resistant (IR) and 21 were constitutively MLS resistant (CR), 6 were noninducibly resistant (NI), and 3 had novel subphenotypes recently reported by our group. Resistance genes were determined by PCR and hybridization methods. Eighty-four of the 100 strains harbored tetM. ermB was detected in all CR and IR strains, and mefA was found in all NI strains; both ermB and mefA were identified in two strains with novel subphenotypes. Pulsed-field gel electrophoresis showed that these antibiotic-resistant M77 strains belonged to at least five different clones.
Jasir
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A
Department of Infectious Diseases, University of Lund, Lund, Sweden.
Tanna
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A
Efstratiou
A
A
Schalén
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C
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D004352:Drug Resistance, Microbial; D016521:Electrophoresis, Gel, Pulsed-Field; D004797:Enzyme-Linked Immunosorbent Assay; D005098:Exotoxins / Q000235:genetics; D006801:Humans; D055231:Lincosamides; D018942:Macrolides; D008565:Membrane Proteins / Q000235:genetics; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012703:Serotyping; D013290:Streptococcal Infections / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D013548:Sweden; D013753:Tetracycline Resistance; D014769:Virginiamycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005098:Exotoxins; D055231:Lincosamides; D018942:Macrolides; D008565:Membrane Proteins; C117980:SpeA protein, Streptococcus pyogenes; C014689:streptococcal M protein; D014769:Virginiamycin