Discerning the role of polymicrobial biofilms in the ascent, prevalence, and extent of heteroresistance in clinical practice

Antimicrobial therapy is facing a worrisome and underappreciated challenge, the phenomenon of heteroresistance (HR). HR has been gradually documented in clinically relevant pathogens (e.g. Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia spp., Acinetobacter baumannii, Klebsiella pneumoniae, Candida spp.) towards several drugs and is believed to complicate the clinical picture of chronic infections. This type of infections are typically mediated by polymicrobial biofilms, wherein microorganisms inherently display a wide range of physiological states, distinct metabolic pathways, diverging refractory levels of stress responses, and a complex network of chemical signals exchange. This review aims to provide an overview on the relevance, prevalence, and implications of HR in clinical settings. Firstly, related terminologies (e.g. resistance, tolerance, persistence), sometimes misunderstood and overlapped, were clarified. Factors generating misleading HR definitions were also uncovered. Secondly, the recent HR incidences reported in clinically relevant pathogens towards different antimicrobials were annotated. The potential mechanisms underlying such occurrences were further elucidated. Finally, the link between HR and biofilms was discussed. The focus was to recognize the presence of heterogeneous levels of resistance within most biofilms, as well as the relevance of polymicrobial biofilms in chronic infectious diseases and their role in resistance spreading. These topics were subject of a critical appraisal, gaining insights into the ascending clinical implications of HR in antimicrobial resistance spreading, which could ultimately help designing effective therapeutic options.This work was supported by the Portuguese Foundation for Science Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2020 unit BioTecNorte operation [NORTE-01-0145-FEDER-000004] funded by the European Regional Development Fund under the scope of Norte2020–Programa Operacional Regional do Norte. The authors also acknowledge COMPETE2020 FCT for the project POCI-01-0145-FEDER-029,841 and for the Scientific Employment Stimulus 2017 grant [CEECIND/01507/2017] (A. M. Sousa).info:eu-repo/semantics/publishedVersio

Propolis: a potential natural product to fight Candida species infections

Aim: To evaluate the effect of propolis against Candida species planktonic cells and its counterpart's biofilms. Materials & methods: The MIC values, time-kill curves and filamentation form inhibition were determined in Candida planktonic cells. The effect of propolis on Candida biofilms was assessed through quantification of CFUs. Results: MIC values, ranging from 220 to 880 µg/ml, demonstrated higher efficiency on C. albicans and C. parapsilosis than on C. tropicalis cells. In addition, propolis was able to prevent Candida species biofilm's formation and eradicate their mature biofilms, coupled with a significant reduction on C. tropicalis and C. albicans filamentation. Conclusion: Propolis is an inhibitor of Candida virulence factors and represents an innovative alternative to fight candidiasis.The authors thank Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (Cnpq) and Fundação Araucária for the financial support received. Flávia Tobaldini-Valerio acknowledges the financial support of CAPES – Proc. 9469/14-1. The authors also thank FCT for the Strategic Project of the UID/BIO/04469/2013 unit, FCT and European Union funds (FEDER/COMPETE) for the project RECI/BBBEBI/0179/2012 (FCOMP-01-0124-FEDER-027462). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed

Inmunoglobulinas en pacientes con actinomicetoma por Nocardia brasiliensis Immunoglobulins in patients with Nocardia brasiliensis actinomycetoma

Considerando que algunos autores han reportado un aumento en la cantidad de algunas inmunoglobulinas en los pacientes con actinomicetoma, en este trabajo nos propusimos determinar diferencias en la producción de IgG1, IgG2, IgG3, IgG4 e IgM en 25 pacientes con actinomicetoma por Nocardia brasiliensis y 25 personas sanas provenientes de una zona endémica de micetoma. La determinación de inmunoglobulinas se realizó por medio de la técnica de ELISA. Para sensibilizar las placas se emplearon 6 antígenos de N. brasiliensis: un antígeno crudo denominado NB y cinco derivados del mismo (NB2, NB4, NB6, NB8 y NB10) separados por punto isoeléctrico. Los niveles de las cuatro subclases de IgG fueron mayores en los sueros de los pacientes que en el suero de los controles, con una diferencia máxima en IgG3 e IgG4; para esta última subclase, los seis antígenos fueron altamente reactivos. La concentración de IgM fue igual en ambos grupos. Es probable que como ocurre en otras infecciones, en la fisiopatogenia del actinomicetoma influya no sólo el aumento o deficiencia de una clase de inmunoglobulina, sino la relación que existe entre las diferentes subclases.Considering that some authors have reported an increasing of some immunoglobulins in actinomycetoma patients, in this study we propose to determine differential production of IgG1, IgG2, IgG3, IgG4 and IgGM in 25 patients with actinomycetoma and 25 healthy individuals from a mycetoma endemic area. Immunoglobulins were determined by ELISA technique. To sensibilize the plates, six Nocardia brasiliensis antigens were used: a crude antigen denominated NB and five derivatives (NB2, NB4, NB6, NB8 and NB10) obtained by their isoelectric point. Results showed that all IgG subclasses were higher in the patients’ sera than in control sera, with a maximal difference to IgG3 and IgG4. To the latter subclass, six antigens were highly reactives. IgM levels were similar in both groups. As it occurs in other infections, in the actinomycetoma pathogenesis probably participate the increase or deficiency of a determined immunoglobulin class, as well as the relationship between different subclasses

Detección de infección por Coccidioides immitis en zonas del estado de Coahuila, México Detection of Coccidioides immitis infection in Coahuila, Mexico

La coccidioidomicosis es una micosis inicialmente pulmonar causada por Coccidioides immitis; puede diseminarse principalmente a sistema nervioso central, huesos y piel. En México se desconoce la frecuencia exacta de esta enfermedad. Nuestro objetivo fue determinar, por intradermorreacción y por serología, los casos de infección por C. immitis en 12 comunidades (10 rurales y dos urbanas) atendidas en el Hospital Rural Nº 79 del Instituto Mexicano del Seguro Social (IMSS) del estado de Coahuila, México. Se estudiaron 668 individuos adultos de ambos sexos; se les aplicó 0,1 ml de coccidioidina por vía intradérmica; después de 72 hs. se midió el diámetro de induración. Fueron seleccionados 180 individuos y a partir del suero se determinaron los niveles de inmunoglobulinas anti-C. immitis por ELISA. Fueron positivos a la coccidioidina 621 sujetos (93%), frecuencia mucho mayor a la reportada previamente en Coahuila. De los 180 sueros estudiados los promedios de densidad óptica (DO) fueron: IgG1, 1,55; IgG2, 0,94; IgG total, 0,33; IgG3, 0,29; IgG4, 0,27; IgM, 0,08. Los valores de IgG1, IgG2 e IgM comparados con las otras inmunoglobulinas fueron estadísticamente significativos. Los valores de IgG1 e IgG2 sugieren contacto frecuente con los antígenos e incluso probables casos de enfermedad no diagnosticada.Coccidioidomycosis is a mycosis firstly pulmonar caused by Coccidioides immitis; it can be disseminated to central nervous system, bones and skin, principaly. In Mexico, the real frequency of the disease is unknown. The aim of this work was to determine, by skin test and by serology, the infection cases by C. immitis in twelve communities (10 rural and two urban), attended in the Hospital Rural Nº 79 at the Instituto Mexicano del Seguro Social (IMSS) from the Coahuila State, Mexico. Six hundred and sixty eight adult individuals of both sexes were studied, to whom 0.1 ml of coccidioidin by intradermal route was applied; 72 h after, the induration diameter was measured. One hundred eighty individuals were selected and seric anti-C. immitis immunoglobulins levels were determined by ELISA. Six hundred twenty one individuals (93%) were positive to coccidioidin, the frequency was much higher than that previously reported in Coahuila. From 180 sera studied, the means of optical density (OD) were: IgG1, 1.55; IgG2, 0.94; total IgG, 0.33; IgG3, 0.29; IgG4, 0.27; IgM, 0.08. The values of IgG1, IgG2 and IgM compared with the other immunoglobulins were statistically significant. The high values of IgG1 and IgG2 suggest frequent contact with the antigen, and probable cases of undiagnosed disease

Effects of fluconazole on Candida glabrata biofilms and its relationship with ABC transporter gene expression

Candida glabrata has emerged as the second most prevalent fungal pathogen and its ability to form biofilms has been considered one of the most important virulence factors, since biofilms present a high tolerance to antifungal agents used in fungal infection treatment. The mechanisms of biofilm tolerance to antifungal agents remain poorly understood. Thus, the aim of this study was to evaluate the effects of fluconazole (FLU) in the formation and control of C. glabrata biofilms and its relation with the expression of genes encoding for ABC transporters, CDR1, SNQ2, and PDR1. For that, MICs values for seven C. glabrata strains were determined and the FLU effect against C. glabrata biofilms evaluated by total biomass quantification and CFUs enumeration. Matrices from biofilms were analyzed in terms of proteins, carbohydrates and DNA content. ABC transporters genes expression was analyzed for quantitative real-time PCR. Additionally to the high amounts of proteins and carbohydrates detected in the extracellular matrices in the presence of FLU, this work showed that the overexpression of efflux pumps is a possible mechanism of biofilm tolerance to FLU and this phenomenon alters the structure of C. glabrata biofilms by creating cell clusters.The authors acknowledge FCT, Portugal, for supporting the projects PTDC/SAU-MIC/119069/2010 and PTDC/EEB-EBI/120495/2010. The group would also like to acknowledge the precious contributions at the beginning of this work from our beloved Prof. Rosario Oliveira