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Clinical and molecular epidemiology of erythromycin-resistant beta-hemolytic lancefield group G streptococci causing bacteremia.

ABSTRACT: Among 100 patients with group G beta-hemolytic streptococcal bacteremia in a 6-year period (1997 to 2002), seven had bacteremia caused by erythromycin-resistant strains. Five of the seven patients had cellulitis and/or abscesses. The two isolates resistant to erythromycin and clindamycin possessed erm genes, one ermTR and the other ermB. The five isolates resistant to erythromycin but sensitive to clindamycin and one of those resistant to both erythromycin and clindamycin possessed mef genes.

SUBMITTER: Woo PC

PROVIDER: S-EPMC262537 | biostudies-literature | 2003 Nov

REPOSITORIES: biostudies-literature

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Clinical and molecular epidemiology of erythromycin-resistant beta-hemolytic lancefield group G streptococci causing bacteremia.

Woo Patrick C Y PC To Amanda P C AP Tse Herman H Lau Susanna K P SK Yuen Kwok-Yung KY

Journal of clinical microbiology 20031101 11

Among 100 patients with group G beta-hemolytic streptococcal bacteremia in a 6-year period (1997 to 2002), seven had bacteremia caused by erythromycin-resistant strains. Five of the seven patients had cellulitis and/or abscesses. The two isolates resistant to erythromycin and clindamycin possessed erm genes, one ermTR and the other ermB. The five isolates resistant to erythromycin but sensitive to clindamycin and one of those resistant to both erythromycin and clindamycin possessed mef genes. ...[more]

PMID: 14605159

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Project description:In the present study, we have evaluated the in vitro antibacterial activity of essential oils from Origanum vulgare, Thymus vulgaris, Lavandula angustifolia, Mentha piperita, and Melaleuca alternifolia against 32 erythromycin-resistant [Mininum Inhibitory Concentration (MIC) ?1 ?g/mL; inducible, constitutive, and e?ux-mediated resistance phenotype; erm(TR), erm(B), and mef(A) genes] and cell-invasive Group A streptococci (GAS) isolated from children with pharyngotonsillitis in Italy. Over the past decades erythromycin resistance in GAS has emerged in several countries; strains combining erythromycin resistance and cell invasiveness may escape ?-lactams because of intracellular location and macrolides because of resistance, resulting in difficulty of eradication and recurrent pharyngitis. Thyme and origanum essential oils demonstrated the highest antimicrobial activity with MICs ranging from 256 to 512 ?g/mL. The phenolic monoterpene carvacrol [2-Methyl-5-(1-methylethyl) phenol] is a major component of the essential oils of Origanum and Thymus plants. MICs of carvacrol ranged from 64 to 256 ?g/mL. In the live/dead assay several dead cells were detected as early as 1 h after incubation with carvacrol at the MIC. In single-step resistance selection studies no resistant mutants were obtained. A synergistic action of carvacrol and erythromycin was detected by the checkerboard assay and calculation of the Fractional Inhibitory Concentration (FIC) Index. A 2- to 2048-fold reduction of the erythromycin MIC was documented in checkerboard assays. Synergy (FIC Index ?0.5) was found in 21/32 strains and was highly significant (p < 0.01) in strains where resistance is expressed only in presence of erythromycin. Synergy was confirmed in 17/23 strains using 24-h time-kill curves in presence of carvacrol and erythromycin. Our findings demonstrated that carvacrol acts either alone or in combination with erythromycin against erythromycin-resistant GAS and could potentially serve as a novel therapeutic tool.

Project description:Little is known about the relative importance of the four species of Lancefield group G beta-hemolytic streptococci in causing bacteremia and the factors that determine the outcome for patients with group G beta-hemolytic streptococcal bacteremia. From 1997 to 2000, 75 group G beta-hemolytic streptococcal strains were isolated from the blood cultures of 66 patients. Sequencing of the 16S rRNA genes of the group G beta-hemolytic streptococci showed that all 75 isolates were Streptococcus dysgalactiae subspecies equisimilis. The API system (20 STREP) and Vitek system (GPI) successfully identified 65 (98.5%) and 62 (93.9%) isolates, respectively, as S. dysgalactiae subspecies equisimilis with >95% confidence, whereas the ATB Expression system (ID32 STREP) only successfully identified 49 isolates (74.2%) as S. dysgalactiae subspecies equisimilis with >95% confidence. The median age of the patients was 76 years (range, 33 to 99 years). Fifty-six patients (85%) were over 60 years old. All patients had underlying diseases. No source of the bacteremia was identified (primary bacteremia) in 34 patients (52%), whereas 17 (26%) had cellulitis and 8 (12%) had bed sore or wound infections. Fifty-eight patients (88%) had community-acquired group G streptococcal bacteremia. Sixty-two patients (94%) had group G Streptococcus recovered in one blood culture, whereas 4 patients (6%) had it recovered in multiple blood cultures. Fifty-nine patients (89%) had group G Streptococcus as the only bacterium recovered in their blood cultures, whereas in 7 patients other bacteria were recovered concomitantly with the group G Streptococcus in the blood cultures (Staphylococcus aureus in 3, Clostridium perfringens in 2, Citrobacter freundii in 1, and Bacteroides fragilis in 1). Overall, 10 patients (15%) died. Male sex, diagnosis other than cellulitis, hospital-acquired bacteremia, and multiple positive blood cultures were associated with mortality [P < 0.005 (relative risk [RR] = 7.6), P < 0.05 (RR = 3.7), P < 0.005 (RR = 5.6), and P < 0.05 (RR = 5.6), respectively]. Unlike group C beta-hemolytic streptococcal bacteremia, group G beta-hemolytic streptococcal bacteremia is not a zoonotic infection in Hong Kong.

Project description:Lateral gene transfer is a significant contributor to the ongoing evolution of many bacterial pathogens, including beta-hemolytic streptococci. Here we provide the first characterization of a novel integrative conjugative element (ICE), ICESde3396, from Streptococcus dysgalactiae subsp. equisimilis (group G streptococcus [GGS]), a bacterium commonly found in the throat and skin of humans. ICESde3396 is 64 kb in size and encodes 66 putative open reading frames. ICESde3396 shares 38 open reading frames with a putative ICE from Streptococcus agalactiae (group B streptococcus [GBS]), ICESa2603. In addition to genes involves in conjugal processes, ICESde3396 also carries genes predicted to be involved in virulence and resistance to various metals. A major feature of ICESde3396 differentiating it from ICESa2603 is the presence of an 18-kb internal recombinogenic region containing four unique gene clusters, which appear to have been acquired from streptococcal and nonstreptococcal bacterial species. The four clusters include two cadmium resistance operons, an arsenic resistance operon, and genes with orthologues in a group A streptococcus (GAS) prophage. Streptococci that naturally harbor ICESde3396 have increased resistance to cadmium and arsenate, indicating the functionality of genes present in the 18-kb recombinogenic region. By marking ICESde3396 with a kanamycin resistance gene, we demonstrate that the ICE is transferable to other GGS isolates as well as GBS and GAS. To investigate the presence of the ICE in clinical streptococcal isolates, we screened 69 isolates (30 GGS, 19 GBS, and 20 GAS isolates) for the presence of three separate regions of ICESde3396. Eleven isolates possessed all three regions, suggesting they harbored ICESde3396-like elements. Another four isolates possessed ICESa2603-like elements. We propose that ICESde3396 is a mobile genetic element that is capable of acquiring DNA from multiple bacterial sources and is a vehicle for dissemination of this DNA through the wider beta-hemolytic streptococcal population.

Dataset Information

Clinical and molecular epidemiology of erythromycin-resistant beta-hemolytic lancefield group G streptococci causing bacteremia.

Publications

Clinical and molecular epidemiology of erythromycin-resistant beta-hemolytic lancefield group G streptococci causing bacteremia.

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