No abstract

Streptococcus pyogenes (group A streptococcus [GAS]) is a versatile human pathogen, and emm1/sequence type 28 (ST28) is the most frequently isolated type from GAS infections. The emm1/ST28 strain is associated with necrotizing fasciitis and streptococcal toxic shock syndrome. Growth-phase regulation is one of the important regulatory mechanisms in GAS, which controls gene expression at restricted phases of growth. CovRS, a two-component regulatory system, is considered the regulator of streptococcal pyrogenic exotoxin B (SpeB) and is thought to be activated in the exponential phase of growth. In the present study, Northern hybridization analysis showed that 52% of the analyzed GAS strains expressed covR at the exponential phase, but 48% of the strains expressed covR at the early stationary phase of growth. Strains transcribing covR at the early stationary phase showed better growth and earlier SpeB expression than the other group of strains. Multilocus sequence typing and pulsed-field gel electrophoresis analysis showed only emm1/ST28 strains (which comprise a clonal cluster) were expressing covR at the early stationary phase of growth, indicating that emm1/ST28 strains have special characteristics which may be related to their worldwide distribution.

Of 1,994 group B streptococcal isolates collected, 26 (1.3%) of the isolates were resistant to levofloxacin, and cross-resistance to other fluoroquinolones was observed. The emergence and prevalence of high-level fluoroquinolone resistance in genetically unrelated isolates were linked to the presence of gyrA, parC, and parE triple mutations in each isolate.

Lower-extremity peripheral arterial disease (PAD) is caused by narrowing or occlusion of vessels in patients like type 2 diabetes mellitus, the elderly and smokers. Patients with PAD are mostly asymptomatic; typical early symptoms of this limb-threatening disorder are intermittent claudication and leg pain, suggesting the necessity for accurate diagnosis by invasive angiography and ankle-brachial pressure index. This index acts as a gold standard reference for PAD diagnosis and categorizes its severity into normal, low-grade and high-grade, with respective cut-off points of ≥0.9, 0.9–0.5 and <0.5. PAD can be assessed using photoplethysmography as a diagnostic screening tool, displaying changes in pulse transit time and shape, and dissimilarities of these changes between lower limbs. The present report proposed photoplethysmogram with fractional-order chaotic system to assess PAD in 14 diabetics and 11 healthy adults, with analysis of dynamic errors based on various butterfly motion patterns, and color relational analysis as classifier for pattern recognition. The results show that the classification of PAD severity among these testees was achieved with high accuracy and efficiency. This noninvasive methodology potentially provides timing and accessible feedback to patients with asymptomatic PAD and their physicians for further invasive diagnosis or strict management of risk factors to intervene in the disease progression.

Due to reduced antibiotic consumption in Taiwan, erythromycin resistance rate had decreased in Streptococcus pyogenes, but it increased in Streptococcus pneumoniae. The objectives of the present study were (1) to determine the erythromycin and clindamycin resistance rate and minimum inhibitory concentration (MIC) of the group B streptococcus (GBS) clinical isolates, and (2) to investigate the mechanism responsible for the macrolide, lincosamide, and group B streptogramin (MLS(B)) resistance. A total of 1,395 GBS isolates were collected from June 2001 to April 2007. Forty-four percent of the GBS isolates were resistant to erythromycin, and 39% were resistant to clindamycin. The annual erythromycin resistance rate increased from 32% in 2001 to 51% in 2004; a significant decrease was observed in 2005 (47%), 2006 (42%), and 2007 (38%). Percentage of erythromycin-resistant isolates with erm(B) gene significantly increased from 72% in 2001 to 90% in 2007. We found that the plasmid encoded zeta gene was present in 13% of the resistant isolates, along with erm(B). When compared to our previous study (1991 to May 2001), the overall erythromycin resistance rate increased from 30% to 44%. erm(B) was the major resistant determinant, and zeta toxin encoding plasmid has a limited role in mediating erythromycin resistance unlike in GAS isolates as reported earlier.