Detection of group A Streptococcus in tonsils from pediatric patients reveals high rate of asymptomatic streptococcal carriage

<p>Abstract</p> <p>Background</p> <p>Group A <it>Streptococcus </it>(GAS) causes acute tonsillopharyngitis in children, and approximately 20% of this population are chronic carriers of GAS. Antibacterial therapy has previously been shown to be insufficient at clearing GAS carriage. Bacterial biofilms are a surface-attached bacterial community that is encased in a matrix of extracellular polymeric substances. Biofilms have been shown to provide a protective niche against the immune response and antibiotic treatments, and are often associated with recurrent or chronic bacterial infections. The objective of this study was to test the hypothesis that GAS is present within tonsil tissue at the time of tonsillectomy.</p> <p>Methods</p> <p>Blinded immunofluorescent and histological methods were employed to evaluate palatine tonsils from children undergoing routine tonsillectomy for adenotonsillar hypertrophy or recurrent GAS tonsillopharyngitis.</p> <p>Results</p> <p>Immunofluorescence analysis using anti-GAS antibody was positive in 11/30 (37%) children who had tonsillectomy for adenotonsillar hypertrophy and in 10/30 (33%) children who had tonsillectomy for recurrent GAS pharyngitis. Fluorescent microscopy with anti-GAS and anti-cytokeratin 8 & 18 antibodies revealed GAS was localized to the tonsillar reticulated crypts. Scanning electron microscopy identified 3-dimensional communities of cocci similar in size and morphology to GAS. The characteristics of these communities are similar to GAS biofilms from <it>in vivo </it>animal models.</p> <p>Conclusion</p> <p>Our study revealed the presence of GAS within the tonsillar reticulated crypts of approximately one-third of children who underwent tonsillectomy for either adenotonsillar hypertrophy or recurrent GAS tonsillopharyngitis at the Wake Forest School of Medicine.</p> <p>Trial Registration</p> <p>The tissue collected was normally discarded tissue and no patient identifiers were collected. Thus, no subjects were formally enrolled.</p

β-Lactam Effects on Mixed Cultures of Common Respiratory Isolates as an Approach to Treatment Effects on Nasopharyngeal Bacterial Population Dynamics

BACKGROUND: Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae are bacteria present in the nasopharynx as part of normal flora. The ecological equilibrium in the nasopharynx can be disrupted by the presence of antibiotics. METHODOLOGY/PRINCIPAL FINDINGS: A computerized two-compartment pharmacodynamic model was used to explore beta-lactam effects on the evolution over time of a bacterial load containing common pharyngeal isolates by simulating free serum concentrations obtained with amoxicillin (AMX) 875 mg tid, amoxicillin/clavulanic acid (AMC) 875/125 mg tid and cefditoren (CDN) 400 mg bid regimens over 24 h. Strains and MICs (microg/ml) of AMX, AMC and CDN were: S. pyogenes (0.03, 0.03 and 0.015), S. pneumoniae (2, 2 and 0.25), a beta-lactamase positive H. influenzae (BL(+); >16, 2 and 0.06) and a beta-lactamase positive AMC-resistant H. influenzae (BLPACR, >16, 8 and 0.06). Mixture of identical 1:1:1:1 volumes of each bacterial suspension were prepared yielding an inocula of approximately 4 x 10(6) cfu/ml. Antibiotic concentrations were measured both in bacterial and in bacteria-free antibiotic simulations. beta-lactamase production decreased AMX concentrations and fT(>MIC) against S. pneumoniae (from 43.2% to 17.7%) or S. pyogenes (from 99.9% to 24.9%), and eradication was precluded. The presence of clavulanic acid countered this effect of co-pathogenicity, and S. pyogenes (but not BL(+) and S. pneumoniae) was eradicated. Resistance of CDN to TEM beta-lactamase avoided this co-pathogenicity effect, and CDN eradicated S. pyogenes and H. influenzae strains (fT(>MIC) >58%), and reduced in 94% S. pneumoniae counts (fT(>MIC) approximately 25%). CONCLUSIONS/SIGNIFICANCE: Co-pathogenicity seems to be gradual since clavulanic acid countered this effect for strains very susceptible to AMX as S. pyogenes but not for strains with AMX MIC values in the limit of susceptibility as S. pneumoniae. There is a potential therapeutic advantage for beta-lactamase resistant cephalosporins with high activity against streptococci

Management of persistent loculated subretinal fluid after pneumatic retinopexy

AIM—To report on the incidence and management of a unique and troublesome complication of pneumatic retinopexy—localised, delayed subretinal fluid absorption (DSRFA).
METHODS—A retrospective chart review was done for all patients who underwent pneumatic retinopexy for retinal detachment over a 5( )year period to identify the patients with DSRFA.
RESULTS—Seven phakic patients (five females, two males, age range 26-87 years) were identified with the phenomenon of delayed resolution of subretinal fluid after pneumatic retinopexy and cryotherapy. In four patients the subretinal fluid involved the macula. Time taken to complete absorption of the subretinal fluid ranged from 10 to 26 months. In one patient there was still residual fluid inferiorly at 18 months of follow up. During the follow up period additional procedures were performed—scleral buckling (five eyes), pars plana vitrectomy (one eye), and mild laser scatter to extramacular areas of shallow subretinal fluid (four eyes). None of these procedures appeared to influence the rate of fluid absorption.
CONCLUSIONS—Loculated subretinal fluid following pneumatic retinopexy may persist for very long periods, extending up to more than 2 years. Additional surgical procedures or laser photocoagulation do not affect the rate of subretinal fluid absorption. Spontaneous reattachment eventually occurs in most eyes, and conservative management is indicated.