Evaluating the antimicrobial and anti-biofilm activity of three synthetic antimicrobial Citropin analogs and their ability to fight against Staphylococcus aureus and Staphylococcus pseudintermedius.

AIMS: We developed three new analogs of the antimicrobial peptide (AMP) Citropin 1.1: DAN-1-13, AJP-1-1, and HHX-2-28, and tested their potential antimicrobial and anti-biofilm activities against S. aureus and S. pseudintermedius. Potential cytotoxic or hemolytic effects were determined using cultured human keratinocytes and erythrocytes to determine their safety. METHODS AND RESULTS: To assess the antimicrobial activity of each compound, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined against methicillin-resistant and methicillin-susceptible strains of S. aureus and S. pseudintermedius. Activity against newly formed and mature biofilms was determined in two clinical isolates using spectrophotometry and scanning electron microscopy (SEM). All three compounds exhibited antimicrobial and bactericidal activity against all studied S. aureus and S. pseudintermedius strains, with MICs ranging from 4-32 µg ml- 1 and MBCs ranging from 8-128 µg ml- 1. Subinhibitory concentrations of all compounds also showed anti-biofilm activity in the two tested isolates. All compounds exhibited limited cytotoxic and hemolytic activity. CONCLUSION: Novel analogs of Citropin 1.1 exhibit anti-microbial and bactericidal activities against S. aureus and S. pseudintermedius isolates and inhibit the biofilm formation of these bacteria.

Engineering a nanoantibiotic system displaying dual mechanism of action.

In recent decades, peptide amphiphiles (PAs) have established themselves as promising self-assembling bioinspired materials in a wide range of medical fields. Herein, we report a dual-therapeutic system constituted by an antimicrobial PA and a cylindrical protease inhibitor (LJC) to achieve broad antimicrobial spectrum and to enhance therapeutic efficacy. We studied two strategies: PA-LJC nanostructures (Encapsulation) and PA nanostructures + free LJC (Combination). Computational modeling using a molecular theory for amphiphile self-assembly captures and explains the morphology of PA-LJC nanostructures and the location of encapsulated LJC in agreement with transmission electron microscopy and two-dimensional (2D) NMR observations. The morphology and release profile of PA-LJC assemblies are strongly correlated to the PA:LJC ratio: high LJC loading induces an initial burst release. We then evaluated the antimicrobial activity of our nanosystems toward gram-positive and gram-negative bacteria. We found that the Combination broadens the spectrum of LJC, reduces the therapeutic concentrations of both agents, and is not impacted by the inoculum effect. Further, the Encapsulation provides additional benefits including bypassing water solubility limitations of LJC and modulating the release of this molecule. The different properties of PA-LJC nanostructures results in different killing profiles, and reduced cytotoxicity and hemolytic activity. Meanwhile, details in membrane alterations caused by each strategy were revealed by various microscopy and fluorescent techniques. Last, in vivo studies in larvae treated by the Encapsulation strategy showed better antimicrobial efficacy than polymyxin B. Collectively, this study established a multifunctional platform using a versatile PA to act as an antibiotic, membrane-penetrating assistant, and slow-release delivery vehicle.

Development and validation of a rabbit model of Pseudomonas aeruginosa non-ventilated pneumonia for preclinical drug development.

Background: New drugs targeting antimicrobial resistant pathogens, including Pseudomonas aeruginosa, have been challenging to evaluate in clinical trials, particularly for the non-ventilated hospital-acquired pneumonia and ventilator-associated pneumonia indications. Development of new antibacterial drugs is facilitated by preclinical animal models that could predict clinical efficacy in patients with these infections. Methods: We report here an FDA-funded study to develop a rabbit model of non-ventilated pneumonia with Pseudomonas aeruginosa by determining the extent to which the natural history of animal disease reproduced human pathophysiology and conducting validation studies to evaluate whether humanized dosing regimens of two antibiotics, meropenem and tobramycin, can halt or reverse disease progression. Results: In a rabbit model of non-ventilated pneumonia, endobronchial challenge with live P. aeruginosa strain 6206, but not with UV-killed Pa6206, caused acute respiratory distress syndrome, as evidenced by acute lung inflammation, pulmonary edema, hemorrhage, severe hypoxemia, hyperlactatemia, neutropenia, thrombocytopenia, and hypoglycemia, which preceded respiratory failure and death. Pa6206 increased >100-fold in the lungs and then disseminated from there to infect distal organs, including spleen and kidneys. At 5 h post-infection, 67% of Pa6206-challenged rabbits had PaO2 <60 mmHg, corresponding to a clinical cut-off when oxygen therapy would be required. When administered at 5 h post-infection, humanized dosing regimens of tobramycin and meropenem reduced mortality to 17-33%, compared to 100% for saline-treated rabbits (P<0.001 by log-rank tests). For meropenem which exhibits time-dependent bactericidal activity, rabbits treated with a humanized meropenem dosing regimen of 80 mg/kg q2h for 24 h achieved 100% T>MIC, resulting in 75% microbiological clearance rate of Pa6206 from the lungs. For tobramycin which exhibits concentration-dependent killing, rabbits treated with a humanized tobramycin dosing regimen of 8 mg/kg q8h for 24 h achieved Cmax/MIC of 9.8 ± 1.4 at 60 min post-dose, resulting in 50% lung microbiological clearance rate. In contrast, rabbits treated with a single tobramycin dose of 2.5 mg/kg had Cmax/MIC of 7.8 ± 0.8 and 8% (1/12) microbiological clearance rate, indicating that this rabbit model can detect dose-response effects. Conclusion: The rabbit model may be used to help predict clinical efficacy of new antibacterial drugs for the treatment of non-ventilated P. aeruginosa pneumonia.

Evaluation of changes in antimicrobial susceptibility in bacteria infecting children and their mothers in pediatric, neonatal-intensive care unit, and gynecology/obstetrics wards of a quaternary referral hospital during the COVID-19 pandemic.

The World Health Organization released a statement warning of increased risk for the incidence of multidrug resistant microorganisms and the absence of new drugs to control such infections soon. Since the beginning of the COVID-19 pandemic, the prescription of antimicrobial agents has increased and may have accelerated the emergence of multidrug resistant (MDR) bacteria. This study aimed to evaluate maternal and pediatric infections within a hospital from January 2019 to December 2021. An observational retrospective cohort study was performed at a quaternary referral hospital in a metropolitan area of Niteroi city, Rio de Janeiro state, Brazil. A total of 196 patients' medical records were analyzed. The data from 90 (45.9%) patients were collected before the SARS-CoV-2 pandemic, 29 (14.8%) from the 2020 pandemic period, and 77 (39.3%) from the 2021 pandemic period. A total of 256 microorganisms were identified during this period. Out of those, 101 (39.5%) were isolated in 2019, 51 (19.9%) in 2020, and 104 (40.6%) in 2021. Antimicrobial susceptibility tests were performed on 196 (76.6%) clinical isolates. The exact binomial test showed that the distribution of Gram-negative bacteria was predominant. The most common microorganism was Escherichia coli (23%; n = 45), followed by Staphylococcus aureus (17.9%, n = 35), Klebsiella pneumoniae (12.8%, n = 25), Enterococcus faecalis (7.7%, n = 15), Staphylococcus epidermidis (6.6%, n = 13) and Pseudomonas aeruginosa (5.6%, n = 11). Staphylococcus aureus was the predominant species among resistant bacteria. Among the antimicrobial agents tested, the following were resistant, presented on a descending scale: penicillin (72.7%, p = 0.001, Binomial test), oxacillin (68.3%, p = 0.006, Binomial test), ampicillin (64.3%, p = 0.003, Binomial test), and ampicillin/sulbactam (54.9%, p = 0.57, Binomial test). Infections with S. aureus were 3.1 times greater in pediatrics and maternal units than in other hospital wards. Despite the global reduction in the incidence of MRSA, we observed an increase in MDR S. aureus in this study. No changes were observed in the frequency of resistance profiles of the clinical isolates after the establishment of the global SARS-CoV-2 pandemic. More comprehensive studies are needed to understand the impact of the global SARS-CoV-2 pandemic on the resistance levels of bacteria associated with neonate and pediatric patients.

"Flattening the curve": effective measures from Niterói city (Rio de Janeiro, Brazil) for COVID-19 control / "Achatando a curva": medidas eficazes da cidade de Niterói (RJ, Brasil) para o controle da COVID-19

Abstract Background In Brazil, some local city government's adopted several measures, which probably had a positive impact on COVID-19 control. Objective To report the distribution of COVID-19 cases in Brazil, Rio de Janeiro state and Niterói city. In parallel, we aimed to demonstrate the preventive strategies adopted by Niterói city. Method Data provided by the Brazilian Ministry of Health and Municipal Health Foundation of Niterói were used to report COVID-19 cases and deaths. For some analysis, data were grouped by week and normalized for 100,000 inhabitants. Results By July 18th, 2020, Brazil reported 2,074,860 cases and 78,772 deaths and Rio de Janeiro state registered 135,230 cases and 11,919 deaths; both still presenting ascendant curves for COVID-19 deaths. In contrast, the rate of new deaths per 100,000 inhabitants is consistently lower in Niterói city. Importantly, we estimated that 712 deaths were prevented by the measures adopted by Niterói city, in comparison to which was observed in Rio de Janeiro. Conclusion The early preventive measures adopted in Niterói city were effective in reducing both the viral spread and rate of deaths. In this regard, this discussion could be relevant for making future decisions during the COVID-19 outbreak in Brazil.

Resumo Introdução No Brasil, algumas cidades adotaram várias medidas que provavelmente tiveram um impacto positivo no controle da Covid-19. Objetivo Relatar a distribuição dos casos de Covid-19 no Brasil, no estado do Rio de Janeiro e na cidade de Niterói. Paralelamente, buscamos demonstrar as estratégias preventivas adotadas pela cidade de Niterói para o controle da Covid-19. Método Dados fornecidos pelo Ministério da Saúde e Fundação Municipal de Saúde de Niterói foram usados ​​para relatar o número de casos e óbitos causados pela Covid-19. Para algumas análises, os dados foram agrupados por semana e normalizados para 100.000 habitantes. Resultados Até 18 de julho de 2020, o Brasil registrou 2.074.860 casos e 78.772 mortes e o estado do Rio de Janeiro registrou 135.230 casos e 11.919 mortes; ambos ainda apresentando curvas ascendentes para mortes por Covid-19. Em contrapartida, a taxa de novos óbitos/100.000 habitantes é consistentemente menor na cidade de Niterói. Estimamos que 712 mortes foram evitadas pelas medidas adotadas pela cidade de Niterói, em comparação com o que foi observado no Rio de Janeiro. Conclusão As medidas preventivas adotadas pela cidade de Niterói foram eficazes na redução tanto da disseminação do vírus quanto da taxa de óbitos. Portanto, esta discussão se mostra relevante para a tomada de decisões futuras durante o surto de Covid-19 no Brasil.

'Hypericum brasiliense: bactericidal and antibiofilm activity against Staphylococcus aureus in vitro'.

Staphylococcus aureus is considered the most common opportunistic pathogen in humans, capable of forming biofilm, increasing the chances of antibiotic resistance and causes several chronic diseases. Biodiversity is a source of inspiration in the search for new agents against these microorganisms. Hitherto, the efficacy of Hypericum sp. extracts as an antibacterial agent has already been demonstrated against Gram-positive and Gram-negative bacteria. In this study, we observed that until 4 µg/mL, the Hypericum brasiliense extract showed bactericidal activity against a clinical multidrug-resistant S. aureus strain (HU25) and also inhibited biofilm formation at 1/2xMIC (confirmed by SEM) and 1/4xMIC. The extract was also proportionally active against 6 h-preformed biofilm to its concentration (1/2xMIC, 1/4xMIC, p value ≤ 0.05). These promising results make Hypericum brasiliense extract a strong candidate to treat S. aureus infections, including anti-biofilm therapy.

Antivirulence Bispecific Monoclonal Antibody-Mediated Protection against Pseudomonas aeruginosa Ventilator-Associated Pneumonia in a Rabbit Model.

Ventilator-associated pneumonia is an important clinical manifestation of the nosocomial pathogen Pseudomonas aeruginosa. We characterized the correlates of protection with MEDI3902, a bispecific human IgG1 monoclonal antibody that targets the P. aeruginosa type 3 secretion system PcrV protein and the Psl exopolysaccharide, in a rabbit model of ventilator-associated pneumonia using lung-protective, low-tidal-volume mechanical ventilation. Rabbits infused with MEDI3902 prophylactically were protected, whereas those pretreated with irrelevant isotype-matched control IgG (c-IgG) succumbed between 12 and 44 h postinfection (100% survival [8/8 rabbits] versus 0% survival [8/8 rabbits]; P < 0.01 by log rank test). Lungs from rabbits pretreated with c-IgG, but not those pretreated with MEDI3902, had bilateral, multifocal areas of marked necrosis, hemorrhage, neutrophilic inflammatory infiltrate, and diffuse fibrinous edema in alveolar spaces. All rabbits pretreated with c-IgG developed worsening bacteremia that peaked at the time of death, whereas only 38% of rabbits pretreated with MEDI3902 (3/8 rabbits) developed such high-grade bacteremia (two-sided Fisher's exact test, P = 0.026). Biomarkers associated with acute respiratory distress syndrome were evaluated longitudinally in blood samples collected every 2 to 4 h to assess systemic pathophysiological changes in rabbits pretreated with MEDI3902 or c-IgG. Biomarkers were sharply increased or decreased in rabbits pretreated with c-IgG but not those pretreated with MEDI3902, including the ratio of arterial oxygen partial pressure to the fraction of inspired oxygen of <300, hypercapnia or hypocapnia, severe lactic acidosis, leukopenia, and neutropenia. Cytokines and chemokines associated with acute respiratory distress syndrome were significantly downregulated in lungs from rabbits pretreated with MEDI3902, compared with c-IgG. These results suggest that MEDI3902 prophylaxis could have potential clinical utility for decreasing the severity of P. aeruginosa ventilator-associated pneumonia.

The Brazilian octocoral Phyllogorgia dilatata as a source of cytotoxic compounds.

The extensive marine biodiversity has proved to be a promising source of substances with biomedical potential. In this study, the cytotoxicity of the Brazilian octocoral Phyllogorgia dilatata (Gorgoniidae) was evaluated against two tumor cell lines and three bacterial strains. The methanol/dichloromethane crude extract presented no antibacterial activity up to the highest concentration tested (512 µg/mL), however it revealed a noteworthy antiproliferative effect against HCT-116 (80%) and MCF-7 (54%) cell lines at 50 µg/mL. Therefore, guided by the cytotoxic activity, a multistep chemical fractionation of the extract provided the subfraction 5 (PDPH2-5) with IC50 values of 3.18 and 17.80 µg/mL against HCT-116 and MCF-7, respectively. The LC-HRMS/MS analysis of PDPH2-5 showed ions of m/z 219.1742 and 219.1743, characterized as (E,E) and (Z,E) germacrone, after a LC-DAD-SPE/NMR analysis of the hexanic fraction and comparisons of NMR data with the literature. Previously reported assessments to the cytotoxic activity of the (E,E)-diastereoisomer disclosed higher IC50 values than that obtained for the PDPH2-5 fraction, suggesting, herein, a potentiated effect of the diastereoisomeric mixture. Such remark encourage further bioactivity studies with stereoisomer mixtures and reduce the urge for compound isolation.

Virulence Factors Found in Nasal Colonization and Infection of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates and Their Ability to Form a Biofilm.

Hospitalizations related to Methicillin-resistant Staphylococcus aureus (MRSA) are frequent, increasing mortality and health costs. In this way, this study aimed to compare the genotypic and phenotypic characteristics of MRSA isolates that colonize and infect patients seen at two hospitals in the city of Niterói-Rio de Janeiro, Brazil. A total of 147 samples collected between March 2013 and December 2015 were phenotyped and genotyped to identify the protein A (SPA) gene, the mec staphylococcal chromosomal cassette (SCCmec), mecA, Panton-Valentine Leucocidin (PVL), icaC, icaR, ACME, and hla virulence genes. The strength of biofilm formation has also been exploited. The prevalence of SCCmec type IV (77.1%) was observed in the colonization group; however, in the invasive infection group, SCCmec type II was prevalent (62.9%). The Multilocus Sequence Typing (MLST), ST5/ST30, and ST5/ST239 analyses were the most frequent clones in colonization, and invasive infection isolates, respectively. Among the isolates selected to assess the ability to form a biofilm, 51.06% were classified as strong biofilm builders. Surprisingly, we observed that isolates other than the Brazilian Epidemic Clone (BEC) have appeared in Brazilian hospitals. The virulence profile has changed among these isolates since the ACME type I and II genes were also identified in this collection.

First report of meticillin-resistant Staphylococcus aureus harboring mecC gene in milk samples from cows with mastitis in southeastern Brazil.

MRSA infection and colonization have been reported in both companion and food-chain animals, highlighting MRSA as an important veterinary and zoonotic pathogen. Another mec allele, the mecC gene, also confers beta-lactam resistance in Staphylococcus aureus and shows 69% nucleotide identity to mecA. The main aim of this study was to investigate the genotypic and clonal profile of methicillin-resistant S. aureus (MRSA) from cows with mastitis in dairy herds. Thirty-five samples suggestive of bovine subclinical mastitis were evaluated, and S. aureus were detected in all of them using both phenotypic and molecular approaches. According to the multilocus sequence typing (MLST), the S. aureus isolates were assigned in five different STs, 21 (60%) showed ST 742, 6 (17%) ST97, 4 (11%) ST1, 2 (6%) ST30, and 2 (6%) ST126. The presence of mecA was not observed in any of these isolates whereas mecC was detected in nine of them (9/35; 26%). The Panton-Valentine leukocidin (PVL) genes were detected in a total of 4 isolates. Among the 35 isolates analyzed, 26 showed resistance to penicillin. Changes in the S. aureus epidemiology due to the detection of MRSA in milk samples from cows presenting with bovine subclinical mastitis may have consequences for public health in Brazil, challenging the empirical therapy and animal management, with potential medical and social outcomes. To the best of our knowledge, this is the first report describing mecC MRSA in Southeastern Brazil.

Prevalence of oxacillin-susceptible methicillin-resistant Staphylococcus aureus nasal carriage and their clonal diversity among patients attending public health-care facilities.

Context: Nosocomial infections arise from many microorganisms, including Staphylococcus aureus. Aims: The aim of this study is to determine the molecular epidemiology of circulating methicillin-resistant S. aureus (MRSA) clones among patients attending community and health-care facilities in Nova Friburgo, RJ, Brazil. Methods: A total of 1002 nasal swab samples were collected from May 2010 to September 2015. S. aureus isolates were identified through phenotypic tests, submitted to antimicrobial susceptibility tests and genotypic analysis to detect mecA, panton-valentine leucocidin (PVL) genes, SCCmec, SPA and multilocus sequencing typing (MLST) typing. Results: We identified 294 (29.3%) isolates as S. aureus and 91 (9.1%) as MRSA. A total of 17 isolates did not present a correlation between phenotypic and genotypic resistance profiles. Among MRSA isolates, 17 (18.7%) carried PVL genes. A total of 20 different SPA types were determined, being grouped by MLST into eight different sequence types. ST5/t002 was the most prevalent genotype found among these isolates. Conclusions: There is a gradual colonisation shift happening in the infection pattern by S. aureus in Brazil. The Brazilian Epidemic Clone (ST239-SCCmec IIIa-PVL-) seems to be substituted by isolates from different clonal complexes, such as ST5, ST8 and ST30. The non-correlation between phenotypic/genotypic resistance profile observed in some isolates suggests the presence of other methicillin resistance mechanisms different from mecA presence or a difference in the nucleotide sequence, which prevents the primers to identify the specific region during polymerase chain reaction reactions. MRSA identification should be based on phenotypic and genotypic testing to ensure the various types of resistance mechanisms.

Biological Evaluation of Selected 1,2,3-triazole Derivatives as Antibacterial and Antibiofilm Agents.

BACKGROUND: Resistance to antimicrobial agents is a major public health problem, being Staphylococcus aureus prevalent in infections in hospital and community environments and, admittedly, related to biofilm formation in biotic and abiotic surfaces. Biofilms form a complex and structured community of microorganisms surrounded by an extracellular matrix adhering to each other and to a surface that gives them even more protection from and resistance against the action of antimicrobial agents, as well as against host defenses. METHODS: Aiming to control and solve these problems, our study sought to evaluate the action of 1,2,3- triazoles against a Staphylococcus aureus isolate in planktonic and in the biofilm form, evaluating the activity of this triazole through Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests. We have also performed cytotoxic evaluation and Scanning Electron Microscopy (SEM) of the biofilms under the treatment of the compound. The 1,2,3-triazole DAN 49 showed bacteriostatic and bactericidal activity (MIC and MBC 128 µg/mL). In addition, its presence interfered with the biofilm formation stage (1/2 MIC, p <0.000001) and demonstrated an effect on young preformed biofilm (2 MICs, p <0.05). RESULTS: Scanning Electron Microscopy images showed a reduction in the cell population and the appearance of deformations on the surface of some bacteria in the biofilm under treatment with the compound. CONCLUSION: Therefore, it was possible to conclude the promising anti-biofilm potential of 1,2,3-triazole, demonstrating the importance of the synthesis of new compounds with biological activity.

Genotypic distribution of Staphylococcus aureus colonizing children and adolescents in daycare centers, an outpatient clinic, and hospitals in a major Brazilian urban setting.

Staphylococcus aureus nasal colonization is a major risk factor for infection. Studies have suggested an epidemiologic shift in the methicillin-resistant S. aureus (MRSA) strains that circulate in Brazil. We conducted cross-sectional studies of MRSA carriage among 1) children and adolescents in community daycare centers, 2) an outpatient clinic, and 3) hospitals in a large Brazilian metropolitan setting. There were 1.500 study subjects, 500 from each locale: 768 (51.2%) carried S. aureus whereas 150 (10%) of these were colonized with MRSA. The most common lineages were the Southwest Pacific (SWP) and the Pediatric clones in all three groups. Roughly 50% of SWP carried Panton-Valentine leukocidin (PVL) (p < 0.01) genes while 63.3% of the Pediatric clones were resistant or intermediately resistant to erythromycin (p < 0.01). This study describes a clonal change of the Brazilian epidemic clone (BEC) to the Pediatric and SWP lineages in Brazil. This finding has implications for clinical management of MRSA infections.

Treatment Efficacy of MEDI3902 in Pseudomonas aeruginosa Bloodstream Infection and Acute Pneumonia Rabbit Models.

Pseudomonas aeruginosa is a challenge for clinicians due to increasing drug resistance and dwindling treatment options. We report on the activity of MEDI3902, an antibody targeting type 3 secretion protein PcrV and Psl exopolysaccharide, in rabbit bloodstream and lung infection models. MEDI3902 prophylaxis or treatment was protective in both acute models and exhibited enhanced activity when combined with a subtherapeutic dose of meropenem. These findings further support MEDI3902 for the prevention or treatment of serious P. aeruginosa infections.

Differences in gram-positive bacterial colonization and antimicrobial resistance among children in a high income inequality setting.

BACKGROUND: Staphylococcus aureus and beta-hemolytic streptococci (BHS) diseases disproportionately affect populations in middle/low-income countries. To assess if this disparity is reflected in colonization by these organisms, we compared their colonization frequency among children from different socioeconomic status (SES) communities in a city with high income inequality. METHODS: Between May-August 2014, we collected nasal and throat swabs to investigate S. aureus and BHS colonization among children who attended private and public pediatric clinics. Patients were classified as high SES, middle/low SES, and slum residents. We investigated the antimicrobial resistance profile, the SCCmec types and the presence of PVL genes among methicillin-resistant S. aureus (MRSA). We also examined the antimicrobial resistance profile and serogroups of BHS. RESULTS: Of 598 children, 221 (37%) were colonized with S. aureus, of which 49 (22%) were MRSA. MRSA colonization was higher in middle/low SES (n = 18; 14%) compared with high SES (n = 17; 6%) and slum (n = 14; 8%) residents (p = 0.01). All MRSA strains were susceptible to clindamycin, nitrofurantoin, and rifampin. The highest non-susceptibility frequency (42.9%) was observed to erythromycin. SCCmec type V was only found in isolates from high SES children; types I and II were found only in middle/low SES children. Ten (20%) MRSA isolates carried PVL genes. Twenty-four (4%) children were BHS carriers. All BHS (n = 8) found in high SES children and six (67%) isolates from slum patients belonged to group A. All group B streptococci were from middle/low SES children, corresponding to five (71%) of the seven BHS isolated in this group. BHS isolates were susceptible to all drugs tested. CONCLUSIONS: Children from different SES communities had distinct bacterial colonization profiles, including MRSA carriage. Public health officials/researchers should consider SES when assessing disease transmission and control measures.

MEDI3902 Correlates of Protection against Severe Pseudomonas aeruginosa Pneumonia in a Rabbit Acute Pneumonia Model.

Pseudomonas aeruginosa is among the most formidable antibiotic-resistant pathogens and is a leading cause of hospital-associated infections. With dwindling options for antibiotic-resistant infections, a new paradigm for treatment and disease resolution is required. MEDI3902, a bispecific antibody targeting the P. aeruginosa type III secretion (T3S) protein PcrV and Psl exopolysaccharide, was previously shown to mediate potent protective activity in murine infection models. With the current challenges associated with the clinical development of narrow-spectrum agents, robust preclinical efficacy data in multiple animal species are desirable. Here, we sought to develop a rabbit P. aeruginosa acute pneumonia model to further evaluate the activity of MEDI3902 intervention. In the rabbit model of acute pneumonia, prophylaxis with MEDI3902 exhibited potent dose-dependent protection, whereas those receiving control IgG developed fatal hemorrhagic necrotizing pneumonia between 12 and 54 h after infection. Blood biomarkers (e.g., partial pressure of oxygen [pO2], partial pressure of carbon dioxide [pCO2], base excess, lactate, and creatinine) were grossly deranged for the vast majority of control IgG-treated animals but remained within normal limits for MEDI3902-treated animals. In addition, MEDI3902-treated animals exhibited a profound reduction in P. aeruginosa organ burden and a marked reduction in the expression of proinflammatory mediators from lung tissue, which correlated with reduced lung histopathology. These results confirm that targeting PcrV and Psl via MEDI3902 is a promising candidate for immunotherapy against P. aeruginosa pneumonia.

Methicillin-resistant Staphylococcus aureus in minas frescal cheese: evaluation of classic enterotoxin genes, antimicrobial resistance and clonal diversity.

This study aimed to investigate classical enterotoxin (sea to see) and mecA genes, by polymerase chain reaction and anitimicrobial susceptibility, by disk diffusion test of Staphylococcus aureus isolated from minas frescal cheese (MFC). All methicillin-resistant S. aureus (MRSA) isolates were investigated for the presence of Panton-Valentine leukocidin (PVL) genes and clonal diversity. Thirty-one S. aureus were isolated from four MFC samples. Seven (22.6%) S. aureus carried mecA gene and two of them carried enterotoxin genes seb/sec and sea/seb. Five (16.1%) S. aureus isolates showed induced resistance to clindamycin and nine (29%) were resistant to multiple -antibiotics (MDR), among these, six were MRSA. No MRSA isolates presented the PVL genes. Four MRSA were grouped into three clones and three isolates were not typable by pulsed field gel electrophoresis. MRSA isolates showed, by multilocus sequence typing, sequence types ST1, ST5, ST72 and ST4304 (new ST) and S. aureus protein A (spa type) t127, t568 and t2703. These data suggest that MFC may constitute a risk to the consumer because of its potential for staphylococcal food poisoning; however it might, also, become one of MRSA and MDR strains disseminator, including clones usually found in the hospital environment.

Emergence of methicillin-resistant Staphylococcus aureus from clonal complex 398 with no livestock association in Brazil.

CC398 is a livestock-associated Staphylococcus aureus. However, it has also been isolated from humans with no previous contact with livestock. A surveillance of methicillin-resistant S. aureus colonisation among children attending public day care centres and hospitals in Niterói and Rio de Janeiro, Brazil, between 2011 and 2013, resulted in the isolation of six cases of CC398 from individuals with no previous exposure to livestock. These isolates showed a high frequency of the erm(C) gene (4/6, 66.7%) with induced resistance to clindamycin, and a relatively high frequency of SEs and lukS/lukF genes. These results suggest the emergence of a non-LA-CC398 in Brazil.

IVIG-mediated protection against necrotizing pneumonia caused by MRSA.

New therapeutic approaches are urgently needed to improve survival outcomes for patients with necrotizing pneumonia caused by Staphylococcus aureus One such approach is adjunctive treatment with intravenous immunoglobulin (IVIG), but clinical practice guidelines offer conflicting recommendations. In a preclinical rabbit model, prophylaxis with IVIG conferred protection against necrotizing pneumonia caused by five different epidemic strains of community-associated methicillin-resistant S. aureus (MRSA) as well as a widespread strain of hospital-associated MRSA. Treatment with IVIG, either alone or in combination with vancomycin or linezolid, improved survival outcomes in this rabbit model. Two specific IVIG antibodies that neutralized the toxic effects of α-hemolysin (Hla) and Panton-Valentine leukocidin (PVL) conferred protection against necrotizing pneumonia in the rabbit model. This mechanism of action of IVIG was uncovered by analyzing loss-of-function mutant bacterial strains containing deletions in 17 genes encoding staphylococcal exotoxins, which revealed only Hla and PVL as having an impact on necrotizing pneumonia. These results demonstrate the potential clinical utility of IVIG in the treatment of severe pneumonia induced by S. aureus.