Staphylococcus warneri: brief literature review / Staphylococcus warneri: breve revisão da literatura

Coagulase-negative Staphylococcus warneri is an opportunistic pathogen that is capable of causing several infections, especially in patients with indwelling medical devices. Antimicrobial resistance is a global challenge for the treatment of infections caused by staphylococci. The most important virulence factor of CoNS is the biofilm-producing ability. This brief literature review discusses aspects of the antimicrobial resistance and virulence factors of the Staphylococcus warneri. Literature about the Staphylococcus warneri listed in PubMed between 2011 and 2021 was reviewed. Staphylococcus warneri is a part of the normal flora of the skin, especially the nares, head, legs, and arms. The importance of S. warneri as a modern-day pathogen is growing, as it has established itself as a successful nosocomial pathogen. S. warneri isolates from these infections are generally resistant to beta-lactam antimicrobial agents. The virulence of S. warneri have been suggested to be multifactorial, including adhesins, enzymes, extracellular toxins, capsule, iron uptake systems, virulence regulators and to adhere to produce biofilm, invade and destroy epithelial cells. The pathogenetic mechanisms of infections their mechanisms of bacterial persistence and evasion of the host’s immune system have not yet been clearly elucidated. Only with deeper studies, which will allow a more comprehensive understanding of its physiological characteristics, will it be possible to design effective strategies against S. warneri

Virulence profile of tigecycline-resistant Gram-negative bacilli isolated from river waters using the Caenorhabditis elegans infection model / Perfil de virulência de bacilos Gram-negativos resistentes à tigeciclina isolados das águas dos rios usando o modelo de infecção por Caenorhabditis elegans

Last-resort antibiotics act as ultimate force to overcome multidrug-resistant strains infections. Cases of tigecycline resistance in gram-negative bacilli in clinical settings are reported worldwide, however, there is no data related to tigecycline resistant strains in river water. This study demonstrates seven tigecycline gram-negative bacilli isolated from river water in Rio de Janeiro metropolitan area, their resistance genes, ability of biofilm formation with/without antibiotics and behavior using the nematode Caenohabidits elegans as infection in vivo model. From 24 gram-negative isolated strains, 16 (66.6%) were classified as multidrug-resistant, however, seven (29.1%) presented resistant to all antimicrobial agents tested, including tigecycline and have been identified by MALDI-TOF as A. baumannii, E. aerogenes and P. agglomerans. All tigecycline-resistant strains presented amplification products for ESBL, AME and PMQR and ability of biofilm formation on hydrophilic and hydro­phobic abiotic surfaces with and without antimicrobial agents. The presence of antimicrobials did not inhibit biofilm formation. Tigecycline-resistant strains differed of OP50 control with P<0,0001 indicating its virulence potential, however, none of them were capable to kill all nematodes during 5 days infection. In conclusion, tigecycline-resistant gram-negative strains have important global public health implications due to the therapeutic problems they pose. Further studies and continuous surveillance of tigecycline-resistant strains in both clinical and aquatic environment remains necessary to track and understand the dissemination of tigecycline resistance

Biofilm formation, interaction and survival within A549 pneumocytes of Klebsiella pneumoniae clinical strains: identification of pulsotypes, multidrug-resistance and genes coding for adhesins: Formação de biofilme, interação e sobrevivência dentro dos pneumócitos A549 de cepas clínicas de Klebsiella pneumoniae: identificação de pulsótipos, multirresistência a drogas e codificação de genes para adesinas

Klebsiella pneumoniaehas become one of the major causes of hospital-acquired infections over decades due to the spread of virulent clones harboring resistant genes to multiple antimicrobial agents. The aim of this study was to investigate phenotypic and genotypic features of virulence mechanism expressed by K. pneumoniae clinical isolates of different PFGE types, including biofilm formation, interaction with pneumocytes A549 lineage and experimental infection by using C. elegans nematodes.  A total of 17 K. pneumoniae strains were isolated from different clinical specimens including blood, urine and respiratory infections. In this present study, 11 strains presented a varied multidrug-resistance profile harboring resistance genes coding for betalactams, aminoglicosydes, fluorquinolones and carbapenemases. PFGE analysis demonstrated the presence of four distinct pulsotypes among K. pneumoniae strains harboring virulence genes for siderophores and fimbiae type 1 and type 3. High adherence and biofilm formation were positively correlated for both polystyrene and glass surfaces in all K. pneumoniae strains analyzed. K. pneumoniae clinical strains showed the ability of adherence, internalization and persistence within human pulmonary epithelial A549 cell line, at different levels. Respiratory infections demonstrated a higher heterogeneity of PFGE types and levels of adherence, intracellular survival and persistence.K. pneumoniae strains were also submitted to Carnohabidits elegans in vivo infection model and data showed that after 24 hr almost 10% of urine-culture isolates worms were dead evidencing virulence profile. Notably, K. pneumoniae strains, presenting virulence genes, was significantly more virulent than those who did not presented any virulence gene after 5 days (survival >60% and >40%)