Antibacterial Assessment of Zinc Sulfide Nanoparticles against Streptococcus pyogenes and Acinetobacter baumannii.

BACKGROUND: Due to the appearance of resistant bacterial strains against the antimicrobial drugs and the reduced efficiency of these valuable resources, the health of a community and the economies of countries have been threatened. OBJECTIVE: In this study, the antibacterial assessment of zinc sulfide nanoparticles (ZnS NPs) against Streptococcus pyogenes and Acinetobacter baumannii has been performed. METHODS: ZnS NPs were synthesized through a co-precipitation method using polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and polyethylene glycol (PEG-4000). The size and morphology of the synthesized ZnS NPs were determined by a scanning electron microscope (SEM) and it was found that the average size of the applied NPs was about 70 nm. In order to evaluate the antibacterial effect of the synthesized ZnS NPs, various concentrations (50µg/mL, 100 µg/mL and 150 µg/mL) of ZnS NPs were prepared. Antibacterial assessments were performed through the disc diffusion method in Mueller Hinton Agar (MHA) culture medium and also the optical density (OD) method was performed by a UV-Vis spectrophotometer in Trypticase™ Soy Broth (TSB) medium. Then, in order to compare the antibacterial effects of the applied NPs, several commercial antibiotics including penicillin, amikacin, ceftazidime and primaxin were used. RESULTS: The achieved results indicated that the antibacterial effects of ZnS NPs had a direct relation along with the concentrations and the concentration of 150 µg/mL showed the highest antibacterial effect in comparison with others. In addition, the ZnS NPs were more effective on Acinetobacter baumannii. CONCLUSION: The findings of this research suggest a novel approach against antibiotic resistance.

The Impact of Clinical Pathways on Antibiotic Prescribing for Acute Otitis Media and Pharyngitis in the Emergency Department.

BACKGROUND: Although Italian pediatric antimicrobial prescription rates are among the highest in Europe, little action has been taken to improve the appropriateness of antimicrobial prescriptions. The primary aim of this study was to assess changes in antibiotic prescription before and after acute otitis media (AOM) and group A streptococcus (GAS) pharyngitis Clinical Pathway (CP) implementation; secondary aims were to compare treatment failures and to assess change in the total antibiotics costs before and after CP implementation. METHODS: Pre-post quasi-experimental study comparing the 6-month period before CP implementation (baseline period: October 15, 2014, through April 15, 2015) to the 6 months after intervention (postintervention: October 15, 2015, through April 15, 2016). RESULTS: Two hundred ninety-five pre- and 278 postintervention emergency department visits were associated with AOM. After CP implementation, there was an increase in "wait and see" approach and a decrease in overall prescription of broad-spectrum antibiotics from 53.2% to 32.4% (P < 0.001). One hundred fifty-one pre- and 166 postimplementation clinic visits were associated with GAS pharyngitis, with a decrease in broad-spectrum prescription after CP implementation (46.4% vs. 6.6%; P < 0.001). For both conditions, no difference was found in treatment failure, and total antibiotics cost was significantly reduced after CP implementation, with a decrease especially in broad-spectrum antibiotics costs. CONCLUSIONS: A reduction in broad-spectrum antibiotic prescriptions and a reduction in the total cost of antibiotics for AOM and GAS pharyngitis along with an increase in "wait and see" prescribing for AOM indicate effectiveness of CP for antimicrobial stewardship in this setting.

In vitro assessment of the ability of probiotics, blueberry and food carbohydrates to prevent S. pyogenes adhesion on pharyngeal epithelium and modulate immune responses.

Group A streptococci (GAS) cause 20-30% of pediatric pharyngitis episodes, which are a major cause of ambulatory care visits. Therefore, a strategy to prevent GAS dissemination in children could significantly benefit public healthcare. Contextually, we assessed the possibility of employing alternative food-grade strategies to be used with the oral probiotic L. helveticus MIMLh5 for the prevention of pharyngeal infections. First, we demonstrated through an antagonism-by-exclusion assay that guaran may potentially prevent S. pyogenes adhesion on pharyngeal cells. Subsequently, we showed that an anthocyanin-rich fraction extracted from wild blueberry (BbE) exerts anti-inflammatory effects on the human macrophage cell line U937. Finally, we showed that BbE reduces interferon-ß expression in MIMLh5-stimulated murine dendritic cells, resulting in a reduction in the pro-inflammatory cytokines IL-12 and TNF-α. In conclusion, this proof-of-concept study indicates that different food-grade strategies may be concomitantly adopted to potentially prevent GAS colonization and modulate local immune defences.

Highly sensitive label-free dual sensor array for rapid detection of wound bacteria.

Wound infections are a critical healthcare concern worldwide. Rapid and effective antibiotic treatments that can mitigate infection severity and prevent the spread of antibiotic resistance are contingent upon timely infection detection. In this work, dual electrochemical pH and cell-attachment sensor arrays were developed for the real-time spatial and temporal monitoring of potential wound infections. Biocompatible polymeric device coatings were integrated to stabilize the sensors and promote bacteria attachment while preventing non-specific cell and protein fouling. High sensitivity (bacteria concentration of 102 colony forming units (CFU)/mL and -88.1±6.3mV/pH over a pH range of 1-13) and stability over 14 days were achieved without the addition of biological recognition elements. The dual sensor array was demonstrated to successfully monitor the growth of both gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) over time through lag and log growth phases and following antibiotic administration and in simulated shallow wounds conditions. The versatile fabrication methods utilized in sensor development, superior sensitivity, prolonged stability, and lack of non-specific sensor fouling may enable long-term in situ sensor array operation in low resource settings.

Antibacterial resistance in Streptococcus pyogenes (GAS) from healthy carriers and tonsillitis patients and association with antibacterial sale in the Faroe Islands.

The aim of this study was to investigate the antibacterial resistance of Streptococcus pyogenes (GAS), and correlate the findings with the sales of erythromycin and tetracycline. General practitioners in the Faroe Islands were recruited to send oropharyngeal swabs. From an ongoing pneumococcal study, nasopharyngeal swabs were sampled from healthy children 0-7 years of age. Erythromycin susceptibility data from Iceland were obtained from the reference laboratory at the Landspitali University Hospital. Susceptibility testing in the Faroe Islands and Iceland was performed according to CLSI methods and criteria. The resistance rate to erythromycin and tetracycline found in patients in the Faroe Islands in 2009/2010 was 6% and 30% respectively. Tetracycline resistance in patients declined significantly from 2009 to 2010 (37-10%, p-value = 0.006 < 0.05) and differed significantly between age groups (p-value = 0.03 < 0.05). In Iceland, there was a peak in erythromycin resistance in 2008 (44%) and a substantial decrease in 2009 (5%). Although the prevalence of erythromycin and tetracycline resistance in the Faroe Islands and Iceland may be associated with antimicrobial use, sudden changes can occur with the introduction of new resistant clones.

A cost-effective strategy for primary prevention of acute rheumatic fever and rheumatic heart disease in children with pharyngitis.

Primary prevention of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) in children depends on prompt and effective diagnosis and treatment of pharyngitis at the primary level of care. Cost-effectiveness modeling shows that the most cost-effective strategy for primary prevention in South Africa (SA) is to use a simple symptomatic clinical decision rule (CDR) to diagnose pharyngitis in children presenting at the primary level of care and then to treat them with a single dose of intramuscular penicillin. Treat All and CDR2+ strategies are affordable and simple and miss few cases of streptococcal pharyngitis at the primary level of care. The CDR2+ strategy is the most cost-effective for primary prevention of ARF and RHD in urban SA and should complement primordial and secondary prevention efforts.

Group a streptococcal diseases and their global burden.

Group A streptococcus (GAS) or Streptococcus pyogenes has been recognised as an important human pathogen since early days of modern microbiology, and it remains among the top ten causes of mortality from an infectious disease. Clinical manifestations attributable to this organism are perhaps the most diverse of any single human pathogen. These encompass invasive GAS infections, with high mortality rates despite effective antimicrobials, toxin-mediated diseases including scarlet fever and streptococcal toxic shock syndrome, the autoimmune sequelae of rheumatic fever and glomerulonephritis with potential for long-term disability, and nuisance manifestations of superficial skin and pharyngeal infection, which continue to consume a sizable proportion of healthcare resources. Although an historical perspective indicates major overall reductions in GAS infection rates in the modern era, chiefly as a result of widespread improvements in socioeconomic circumstances, this pathogen remains as a leading infectious cause of global morbidity and mortality. More than 18 million people globally are estimated to suffer from serious GAS disease. This burden disproportionally affects least affluent populations, and is a major cause of illness and death among children and young adults, including pregnant women, in low-resource settings. We review GAS transmission characteristics and prevention strategies, historical and geographical trends and report on the estimated global burden disease attributable to GAS. The lack of systematic reporting makes accurate estimation of rates difficult. This highlights the need to support improved surveillance and epidemiological research in low-resource settings, in order to enable better assessment of national and global disease burdens, target control strategies appropriately and assess the success of control interventions.

Prevalence of ß-hemolytic Streptococcus in children with special health care needs.

UNLABELLED: Pharyngotonsillitis by ß-hemolytic Streptococcus mostly affects children and immunocompromised, being Streptococcus pyogenes (Group A) the most common agent in bacterial pharyngotonsillitis. AIM: This work targeted the research of ß-hemolytic Streptococcus Group-A (SBHGA) and No-A (SBHGNA) in the oropharynx of individuals with special health needs from the APAE (Maceió-AL). METHOD: A prospective study with oropharynx samples from patients with Down syndrome and other mental disorders (test) and students from a private school (control) aged 5-15 years. Cultures in blood agar (5%) were identified through Gram/catalase tests and bacitracin/trimethoprim-sulfamethoxazole disk diffusion method, applying the chi-squared statistical analysis. RESULTS: A total of 222 bacterial colonies were isolated in 74 individuals from APAE and 65 in the control group. In the test group, previous episodes of pharyngotonsillitis were reported by 36.49% (27/74) and 9.46% (7/74) were diagnosed with symptoms and/or signs suggestive of oropharynx infection. No positive sample of S. pyogenes was confirmed at APAE, being all samples classified as SBHGNA, with 5 SBHGA in the control group. CONCLUSION: The early identification of ß-hemolytic Streptococcus is important for the fast treatment of pharyngotonsillitis and the absence of S. pyogenes avoid future suppurative or not-suppurative sequels in the group from APAE.

Prevalência de Streptococcus β-hemolítico em crianças portadoras de necessidades especiais / Prevalence of β-hemolytic Streptococcus in children with special health care needs

Faringotonsilite causada por Streptococcus β-hemolítico afeta principalmente crianças e imunocomprometidos, sendo Streptococcus pyogenes (Grupo A) o agente mais comum em faringotonsilites bacterianas. OBJETIVO: Este trabalho objetivou a busca por Streptococcus β-hemolítico do Grupo A (SBHGA) e Não A (SBHGNA) na orofaringe de indivíduos com necessidades especiais da APAE (Maceió-AL). MÉTODO:Estudo prospectivo com amostras da orofaringe de pacientes com síndrome de Down e outras desordens mentais (teste) e estudantes de escola privada (controle) de 5-15 anos. Culturas em ágar sangue (5%) foram identificadas através dos testes de Gram/catalase e o método de disco difusão com bacitracina/sulfametoxazol-trimetoprim, aplicando-se o teste Chi-quadrado em análises estatísticas. RESULTADOS: Um total de 222 colônias bacterianas foram isoladas em 74 indivíduos da APAE e 65 no grupo controle. No grupo teste, episódios prévios de faringotonsilites foram relatados por 36,49% (27/74) e 9,46% (7/74) foram diagnosticados com sintomas e/ou sinais sugestivos de infecção orofaríngea. Nenhuma amostra de S. pyogenes foi confirmada na APAE, sendo todas identificadas como SBHGNA, com cinco SBHGA no grupo controle. CONCLUSÃO:A identificação precoce de Streptococcus β-hemolítico é importante para o tratamento rápido de faringotonsilites e a ausência de S. pyogenes evita futuras sequelas supurativas ou não supurativas no grupo da APAE.

Pharyngotonsillitis by β-hemolytic Streptococcus mostly affects children and imunocompromissed, being Streptococcuspyogenes (Group A) the most common agent in bacterial pharyngotonsillitis. AIM:This work targeted the research of β-hemolytic Streptococcus Group-A (SBHGA) and No-A (SBHGNA) in the oropharynx of individuals with special health needs from the APAE (Maceió-AL). METHOD: A prospective study with oropharynx samples from patients with Down syndrome and other mental disorders (test) and students from a private school (control) aged 5-15 years. Cultures in blood agar (5%) were identified through Gram/catalase tests and bacitracin/trimethoprim-sulfamethoxazole disk diffusion method, applying the chi-squared statistical analysis. RESULTS: A total of 222 bacterial colonies were isolated in 74 individuals from APAE and 65 in the control group. In the test group, previous episodes of pharyngotonsillitis were reported by 36.49% (27/74) and 9.46% (7/74) were diagnosed with symptoms and/or signs suggestive of oropharynx infection. No positive sample of S. pyogenes was confirmed at APAE, being all samples classified as SBHGNA, with 5 SBHGA in the control group. CONCLUSION: The early identification of β-hemolytic Steptococcus is important for the fast treatment of pharyngotonsillitis and the absence of S. pyogenes avoid future suppurative or not-suppurative sequels in the group from APAE.

Standardizing an in vitro procedure for the evaluation of the antimicrobial activity of wound dressings and the assessment of three wound dressings.

OBJECTIVES: A wide selection of wound dressings is available on the market with varying claims of antimicrobial efficacy. A valid standard method for evaluation of their antimicrobial activity in vitro has not been established. In this study we suggest a standardized time-kill assay procedure for antimicrobial activity evaluation of wound dressings in order to make studies more comparable and reproducible. We also tested two silver-containing dressings and one propolis-containing dressing against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Pseudomonas aeruginosa using our proposed procedure. METHODS: The following dressings were tested: the ionic silver-containing dressing (ISCD), nanocrystalline silver coated dressing (NSCD) and a propolis-containing dressing (PCD) that is in development. A time-kill assay and the zone of inhibition test were used in the study. RESULTS: NSCD exhibited the most potent antibacterial activity against all organisms. ISDC also demonstrated good antibacterial activity although inferior to NSCD. PCD did not show any bactericidal effect. CONCLUSIONS: Based on our findings we suggest that a time-kill assay with a 1 cm(2) dressing is used for evaluation of the antimicrobial activity of wound dressings, and that the dressings should be exposed to a standardized inoculum of 1-1.5 × 10(6) cfu/mL with Mueller-Hinton broth as the most appropriate medium. PCD requires further research to establish its clinical value.

Application of pharmacokinetic-pharmacodynamic modeling and the justification of a novel fusidic acid dosing regimen: raising Lazarus from the dead.

Perhaps the most crucial step in the clinical development of an antimicrobial agent is the selection of a dosing regimen. Such decisions impact not only the success of a program but also the well being of individual patients, the emergence of resistance, and society as a whole. For fusidic acid, the selection of a dosing regimen for the treatment of patients with acute bacterial skin and skin-structure infection (ABSSSI) was based on the integration of knowledge gained from human population pharmacokinetic, in vitro infection, and mathematical models. The overarching goal of these studies was to identify a dosing regimen that would maximize the probabilities of positive clinical outcomes and limit the emergence of bacterial resistance during therapy. Novel dosing regimens identified included 1500 mg twice daily on day 1 followed by 600 mg twice daily for 10-14 days, a regimen that was subsequently found to be effective in a phase 2 clinical study of patients with ABSSSI. Herein, we review the data supporting the use of this novel fusidic acid dosing regimen, which will undergo further clinical evaluation in phase 3 clinical trials.

[Strategy and tactics of epidemiologic surveillance for streptococcal infection].

State-of-the-art views on concept and main routes of epidemiologic surveillance for group A streptococcal infection. Thorough characteristics of surveillance subsystems: information-analytic, diagnostic and managerial. Importance of microbiological monitoring, which includes determination of species composition of group A streptococci as well as study of their biological and genetic characteristics, susceptibility to antibiotics and disinfectants, is underlined. Appropriateness of using pulse-electrophoresis, sequencing of erythrogenic toxins' genes and emm-typing of the pathogen was substantiated. This allows to identify identical (epidemic) as well as related and non-related clusters of studied cultures and widens the capabilities to study features of development of infection's epidemic process. Management decisions implemented through the system of preventive and antiepidemic measures, which are regulated by sanitary rules and methodic guidelines.

Semimechanistic pharmacokinetic/pharmacodynamic model for assessment of activity of antibacterial agents from time-kill curve experiments.

Dosing of antibacterial agents is generally based on point estimates of the effect, even though bacteria exposed to antibiotics show complex kinetic behaviors. The use of the whole time course of the observed effects would be more advantageous. The aim of the present study was to develop a semimechanistic pharmacokinetic (PK)/pharmacodynamic (PD) model characterizing the events seen in a bacterial system when it is exposed to antibacterial agents with different mechanisms of action. Time-kill curve experiments were performed with a strain of Streptococcus pyogenes exposed to a wide range of concentrations of the following antibiotics: benzylpenicillin, cefuroxime, erythromycin, moxifloxacin, and vancomycin. Bacterial counts were monitored with frequent sampling during the experiment. A simultaneous fit of all data was accomplished. The degradation of the drugs was monitored and corrected for in the model, and a link model was used to account for an effect delay. In the final PK/PD model, the total bacterial population was divided into two subpopulations: one growing drug-susceptible population and one resting insusceptible population. The drug effect was included as an increase of the killing rate of bacteria in the susceptible state, according to a maximum-effect (E(max)) model. An internal model validation showed that the model was robust and had good predictability. In conclusion, for all drugs, the final PK/PD model successfully described bacterial growth and killing kinetics when the bacteria were exposed to different antibiotic concentrations. The semimechanistic model that was developed might, after further refinement, serve as a tool for the development of optimal dosing strategies for antibacterial agents.

Explaining the poor bacteriologic eradication rate of single-dose ceftriaxone in group a streptococcal tonsillopharyngitis: a reverse engineering solution using pharmacodynamic modeling.

OBJECTIVE: To explore pharmacokinetic factors underlying the poor bacteriologic eradication rate with a single 500-mg dose of ceftriaxone for streptococcal tonsillopharyngitis and to identify the minimum ceftriaxone dose required for effective treatment. METHODS: Population modeling techniques were applied to pharmacokinetic data derived from paired plasma and tonsil samples from 153 children to assess the contribution of pharmacokinetic variability to patients' responses to ceftriaxone. In addition, a Monte Carlo simulation was performed to determine (1) the amount of time that free ceftriaxone concentrations must exceed the minimum inhibitory concentration (MIC) of group A Streptococcus to achieve bacteriologic eradication and (2) the ceftriaxone dose required to maintain free drug concentrations above the target MIC for the requisite amount of time. Ceftriaxone MICs for group A Streptococcus were obtained from a previous trial, in which all MICs (n = 115) were < or = 0.064 mg/L; 33.9% were susceptible at < or = 0.016 mg/L, 66.4% were susceptible at 0.032 mg/L, and 1.7% were susceptible at 0.064 mg/L. RESULTS: Mean population pharmacokinetic parameters and their variances reflected substantial variability of clearance and half-life in the target population. Tonsillar ceftriaxone protein binding was 89.1%. The proportions of 1000 simulated patients with free ceftriaxone concentrations that exceeded MICs of 0.016 mg/L, 0.032 mg/L, and 0.064 mg/L at 24 hours were 71.7%, 65.4%, and 57.2%, respectively, and at 48 hours were 41.8%, 35.8%, and 28.6%, respectively. The amount of time that free ceftriaxone concentrations need to exceed MIC to achieve bacteriologic success was estimated to be 36 hours. Using this time criterion, two 500-mg doses of ceftriaxone separated by 18 hours should achieve a bacteriologic cure rate of approximately 95%. CONCLUSIONS: Pharmacokinetic variability and high ceftriaxone tonsillar protein binding explain the high microbiologic failure rate for a single 500-mg dose of ceftriaxone in group A streptococcal tonsillopharyngitis. Monte Carlo simulation suggests that a second dose administered 18 hours after the first will be required to achieve an acceptable bacteriologic cure rate.

A clinical decision rule for management of streptococcal pharyngitis in low-resource settings.

BACKGROUND: Most of the world's children live in regions where laboratory facilities are not available. In these regions, clinical prediction rules can be useful to guide clinicians' decisions on antibiotic therapy for streptococcal pharyngitis, and to reduce routine presumptive antibiotic therapy for all pharyngitis. METHODS: Prospective cohort study to assess diagnostic signs and develop a prediction rule. Bivariate and multivariate analyses were used to develop clinical rules. Participants were 410 children in Cairo, Egypt, aged from 2 to 12 y, presenting with complaint of sore throat and whose parents provided consent. Main outcome measures included presence of signs and symptoms, and positive group A beta hemolytic streptococcal (GABHS) culture. RESULTS: 101 (24.6%) children had positive GABHS culture. Pharyngeal exudate, tender or enlarged anterior cervical lymph nodes, season, absence of rash, or cough or rhinitis were associated with positive culture in bivariate and multivariate analyses. Three variables (enlarged nodes, no rash, no rhinitis), when used in a cumulative score, showed 92% sensitivity and 38% specificity in these children. CONCLUSIONS: The proposed three-variable clinical prediction rule for GABHS may be useful when diagnostic laboratories are not available. In this setting, the rule identified more than 90% of true cases. Compared to universal treatment of all pharyngitis, the rule will reduce antibiotic use in GABHS-negative cases by about 40%.

Retrospective assessment of subacute or chronic osteomyelitis in children and young adults.

To identify factors associated with and to describe treatment outcomes of pediatric subacute or chronic osteomyelitis (S/CO), we retrospectively identified 52 patients with S/CO from January 1994 to November 1999 seen at a large pediatric hospital infectious disease clinic. S/CO was defined by the following: >10 days of clinical symptoms; radiographic, surgical, or pathologic changes consistent with S/CO; or relapse of prior osteomyelitis. Of these patients 63% were male, median age 9 years. Bones involved included vertebra (19% of subjects), femur (17%), finger (12%), humerus (10%), and tibia (8%). Sixty-five percent had at least 1 risk factor (most commonly hardware, neurologic disease or preceding trauma, sepsis, or surgery). Blood, bone, or wound aspirate cultures were positive in 67%, most commonly for Staphylococcus aureus. Erythrocyte sedimentation rate (ESR) was elevated in 88% of 41 patients at the time of diagnosis. Intravenous antibiotics were given for a median of 6 weeks and oral antibiotics for a median of 4.5 months. One child had a complication. In conclusion, consideration of S/CO should be high when predisposing factors are present. ESR may be useful for determining effectiveness and duration of therapy. With prolonged antibiotic therapy nearly all patients demonstrated resolution of disease.

Cost-effective workup for tonsillitis. Testing, treatment, and potential complications.

Despite increased strictness in surgical criteria, tonsillectomy continues to be one of the most common outpatient surgical procedures performed in the United States. The primary care physician is integrally involved in the diagnosis and treatment of tonsillitis, the chief reason for tonsillectomy. This article gives guidelines for diagnosis and management of tonsillitis and provides an overview of its potential complications.

Flow cytometric assessment of susceptibilities of Streptococcus pyogenes to erythromycin and rokitamycin.

The effects of erythromycin (a 14-membered ring macrolide) and rokitamycin (a 16-membered ring macrolide) on the viability of the Streptococcus pyogenes M phenotype were studied by means of flow cytometry and fluorescence microscopy by using a combination of two fluorochromes (syto 9 and propidium iodide) that stains live bacteria green and dead bacteria red. In order to apply the flow cytometry, a bacterial sonication procedure was expressly set up to separate single cells from the long, intralaced S. pyogenes chains of up to 30 to 40 cells that have previously prevented the application of flow cytometry to this type of bacteria. The association of flow cytometry using an appropriate sonication procedure, together with a combination of fluorescent probes, offered the possibility of very quickly investigating the different microbiological effects of rokitamycin at 2 microg/ml, which was active on the S. pyogenes M phenotype, and of erythromycin at doses of up to 32 microg/ml, which was not.