Heterogeneous production of proteases from Brazilian clinical isolates of Pseudomonas aeruginosa

Potassium Chloride, Sodium Lactate and Sodium Citrate Impaired the Antimicrobial Resistance and Virulence of Pseudomonas aeruginosa NT06 Isolated from Fish

Sodium chloride (NaCl) is a commonly used additive in minimally processed fish-based products. The addition of NaCl to fish products and packaging in a modified atmosphere is usually efficient with regard to limiting the occurrence of the aquatic environmental pathogen Pseudomonas aeruginosa. Given the negative effects of excess NaCl in the diet, there is a growing demand to reduce NaCl in food products with safer substituents, but the knowledge of their impact on antibiotic resistant P. aeruginosa is limited. This study aimed to evaluate the physiological and transcriptome characteristics of P. aeruginosa NT06 isolated from fish and to determine the effect of selected concentrations of alternative NaCl compounds (KCl/NaL/NaC) on the P. aeruginosa NT06 virulence phenotype and genotype. In the study, among the isolated microorganisms, P. aeruginosa NT06 showed the highest antibiotic resistance (to ampicillin, ceftriaxone, nalidixic acid, and norfloxacin) and the ability to grow at 4 °C. The Comprehensive Antibiotic Resistance Database (CARD) and the Virulence Factor Database (VFDB) revealed the presence of 24 and 134 gene products assigned to AMR and VF in the P. aeruginosa NT06 transcriptome, respectively. KCl, KCl/NaL and KCl/NaL/NaC inhibited pyocyanin biosynthesis, elastase activity, and protease activity from 40 to 77%. The above virulence phenotypic observations were confirmed via RT-qPCR analyses, which showed that all tested AMR and VF genes were the most downregulated due to KCl/NaL/NaC treatment. In conclusion, this study provides insight into the potential AMR and VF among foodborne P. aeruginosa and the possible impairment of those features by KCl, NaL, and NaC, which exert synergistic effects and can be used in minimally processed fish-based products.

Study of Antimicrobial Resistance, Biofilm Formation, and Motility of Pseudomonas aeruginosa Derived from Urine Samples

Pseudomonas aeruginosa causes urinary tract infections associated with catheters by forming biofilms on the surface of indwelling catheters. Therefore, controlling the spread of the bacteria is crucial to preventing its transmission in hospitals and the environment. Thus, our objective was to determine the antibiotic susceptibility profiles of twenty-five P. aeruginosa isolates from UTIs at the Medical Center of Trás-os-Montes and Alto Douro (CHTMAD). Biofilm formation and motility are also virulence factors studied in this work. Out of the twenty-five P. aeruginosa isolates, 16% exhibited multidrug resistance, being resistant to at least three classes of antibiotics. However, the isolates showed a high prevalence of susceptibility to amikacin and tobramycin. Resistance to carbapenem antibiotics, essential for treating infections when other antibiotics fail, was low in this study, Notably, 92% of the isolates demonstrated intermediate sensitivity to ciprofloxacin, raising concerns about its efficacy in controlling the disease. Genotypic analysis revealed the presence of various β-lactamase genes, with class B metallo-β-lactamases (MBLs) being the most common. The bla_NDM, bla_SPM, and bla_VIM-VIM2 genes were detected in 16%, 60%, and 12% of the strains, respectively. The presence of these genes highlights the emerging threat of MBL-mediated resistance. Additionally, virulence gene analysis showed varying prevalence rates among the strains. The exoU gene, associated with cytotoxicity, was found in only one isolate, while other genes such as exoS, exoA, exoY, and exoT had a high prevalence. The toxA and lasB genes were present in all isolates, whereas the lasA gene was absent. The presence of various virulence genes suggests the potential of these strains to cause severe infections. This pathogen demonstrated proficiency in producing biofilms, as 92% of the isolates were found to be capable of doing so. Currently, antibiotic resistance is one of the most serious public health problems, as options become inadequate with the continued emergence and spread of multidrug-resistant strains, combined with the high rate of biofilm production and the ease of dissemination. In conclusion, this study provides insights into the antibiotic resistance and virulence profiles of P. aeruginosa strains isolated from human urine infections, highlighting the need for continued surveillance and appropriate therapeutic approaches.

Bacillus subtilis BR4 derived stigmatellin Y interferes Pqs-PqsR mediated quorum sensing system of Pseudomonas aeruginosa

Cell-to-cell communication is essentially required in bacteria for the production of multiple virulence factors and successful colonization in the host. Targeting the virulence factors production without hampering the growth of the pathogens is a potential strategy to control pathogenesis. To accomplish this, a total of 43 mangrove isolates were screened for quorum quenching (QQ) activity against Pseudomonas aeruginosa (PA), in which eight bacteria have shown antibiofilm activity without hampering the growth of the PA. Prominent QQ activity was observed in Bacillus subtilis BR4. Previously, we found that BR4 produces stigmatellin Y, a structural analogue of PQS signal of PA, which could competitively bind with PqsR receptor and inhibits the quorum sensing (QS) system of PA. Further, stigmatellin Y containing ethyl acetate extract (S-EAE) (100 µg ml-1 ) of BR4 significantly inhibits (p < 0.001) the biofilm formation of PA. Confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) analysis also fortified the QQ activity of BR4. Furthermore, S-EAE of BR4 (500 µg ml-1 ) has significantly reduced the production of virulence factors, including protease, elastase, pyocyanin and extracellular polysaccharides substances. Furthermore, liquid chromatography-mass spectrometry (LC-MS)/MS analysis affirms that BR4 intercepts the PQS-mediated QS system by reducing the synthesis of as many PQS signals, including precursor molecule (243.162313 Da) of PQS signal. Thus, S-EAE of B. subtilis BR4 could be used as a promising therapeutic agent to combat QS system-mediated pathogenesis of PA. Further therapeutic potentials of stigmatellin Y to be evaluated in clinical studies for the treatment of multidrug resistant PA.

Antimicrobial resistance and virulence characteristics in ERIC-PCR typed biofilm forming isolates of P. aeruginosa

Pseudomonas aeruginosa is a serious pathogen particularly in immunocompromised patients. In this work, 103 clinical isolates of P. aeruginosa were collected and classified into weak, moderate, and strong biofilm producers according to their biofilm forming abilities via tissue culture plate method. The antimicrobial resistance and the presence of different virulence genes were investigated via disc diffusion method and polymerase chain reaction respectively. Moreover, ERIC-PCR typing was performed to investigate the genetic diversity among the clinical isolates. No significant correlation was observed between biofilm formation and resistance to each antimicrobial agent. Similar observation was detected concerning the multidrug resistance and biofilm formation. Regarding virulence genes, algD gene was harbored by all isolates (100%). Only pelA and phzM were significantly prevalent in strong biofilm producers. Additionally, the mean virulence score was higher in strong biofilm producers (9.33) than moderate (8.62) and weak (7) biofilm producers. Moreover, there was a significant correlation between the overall virulence score of the isolates and its ability to form biofilm. ERIC-PCR genotyping revealed the presence of 99 different ERIC patterns based on 70% similarity, and the different ERIC patterns were categorized into 8 clusters. 100% similarity indicates the possibility of cross-colonization in P. aeruginosa infections.

Characterization of Pseudomonas aeruginosa isolated from various environmental niches: New STs and occurrence of antibiotic susceptible "high-risk clones"

The aim of this study was to investigate the antimicrobial phenotypes, major virulence factors, and the molecular typing of 66 P. aeruginosa isolates collected from various sources: human patients and hospital environment, raw milk, poultry meat, chicken/sheep fecal samples, wastewater, thermal water, and seawater. All isolates, except one, were susceptible to all tested antibiotics. exoA, lasB, rhlR, and lasR genes were harbored by 60 isolates. Forty-six, 18, and 2 isolates amplified exoS, exoU, and exoS+exoU genes, respectively. Twenty-one isolates showed high elastase and pigment production. The PFGE typing identified 26 pulsotypes. Some pulsotypes included isolates from different environmental niches and areas. Twelve selected isolates were typed by MLST and eight different STs were found, three of them were new. Our results highlighted the dissemination of some clones amongst different settings and the occurrence of antibiotic susceptible 'high-risk clones' that might be very harmful when acquiring genes encoding antibiotic resistance.

Anti-Virulence Strategy against the Multidrug-Resistant Bacterial Pathogen Pseudomonas aeruginosa: Pseudolysin (Elastase B) as a Potential Druggable Target

Pseudomonas aeruginosa is a non-fermentative, gram-negative bacterium that is one of the most common pathogens responsible for hospital-acquired infections worldwide. The management of the infections caused by P. aeruginosa represents a huge challenge in the healthcare settings due to the increased emergence of resistant isolates, some of them resistant to all the currently available antimicrobials, which results in elevated morbimortality rates. Consequently, the development of new therapeutic strategies against multidrug-resistant P. aeruginosa is urgent and needful. P. aeruginosa is wellrecognized for its extreme genetic versatility and its ability to produce a lush variety of virulence factors. In this context, pseudolysin (or elastase B) outstands as a pivotal virulence attribute during the infectious process, playing multifunctional roles in different aspects of the pathogen-host interaction. This protein is a 33-kDa neutral zinc-dependent metallopeptidase that is the most abundant peptidase found in pseudomonal secretions, which contributes to the invasiveness of P. aeruginosa due to its ability to cleave several extracellular matrix proteins and to disrupt the basolateral intercellular junctions present in the host tissues. Moreover, pseudolysin makes P. aeruginosa able to overcome host defenses by the hydrolysis of many immunologically relevant molecules, including antibodies and complement components. The attenuation of this striking peptidase therefore emerges as an alternative and promising antivirulence strategy to combat antibiotic-refractory infections caused by P. aeruginosa. The anti-virulence approach aims to disarm the P. aeruginosa infective arsenal by inhibiting the expression/activity of bacterial virulence factors in order to reduce the invasiveness of P. aeruginosa, avoiding the emergence of resistance since the proliferation is not affected. This review summarizes the most relevant features of pseudolysin and highlights this enzyme as a promising target for the development of new anti-virulence compounds.

Virulence factors and integrons are associated with MDR and XDR phenotypes in nosocomial strains of Pseudomonas aeruginosa in a Venezuelan university hospital

Multidrug resistance (MDR), virulence and transferable elements potentiate Pseudomonas aeruginosa's role as an opportunistic pathogen creating a high risk for public health. In this study, we evaluated the possible association of multidrug resistance, virulence factors and integrons with intrahospital P. aeruginosa strains isolated from patients at Cumana hospital, Venezuela. Relevant clinical-epidemiological data were collected to study 176 strains (2009-2016) isolated from different hospital units. Bacterial resistance was classified as susceptible, low-level resistant (LDR), multidrug resistant (MDR) and extensively drug-resistant (XDR). Most strains produced pyoverdine, DNase, gelatinase and hemolysin. Around 73% of the strains showed some type of movement. MDR and XDR strains increased from 2009 (24.2% and 4.8%, respectively) to 2016 (53.1% and 18.8%); while LDR decreased from 64.5% to 6.3%. The exoU and exoS genes were found in a significant number of strains (38.1 and 7.4%, respectively). Class I integrons were detected in 35.8% of the strains and the frequency was associated with resistance (42.9, 22.4, 41.4 and 61.9%, for susceptible, LDR, MDR and XDR, respectively). The MDR/XDR strains were positively associated with hemolysins and exoU, but negatively associated with bacterial twitching. MDR/XDR phenotypes were also associated with the Intensive Care Unit (ICU), septicemia, bronchial infection and diabetic foot ulcers, as well as long hospital stay (≥10 days) and previous antimicrobial treatment. High frequency of MDR/XDR strains and their association with class I integrons and virulence factors can increase the infection potential, as well as morbidity and mortality of patients attending this hospital and could spread infection to the community, creating a health risk for the region.

Diallyl disulfide from garlic oil inhibits Pseudomonas aeruginosa virulence factors by inactivating key quorum sensing genes

Garlic oil can disrupt the quorum sensing (QS) pathways of the opportunistic pathogen Pseudomonas aeruginosa; however, the underlying mechanisms for this effect are unclear. Diallyl disulfide (DADS) is one of the most abundant sulfur-containing compounds in garlic oil. This study investigated the effects of DADS on the growth, virulence factor production (elastase, pyocyanin, biofilm, and swarming motility), and essential gene expression of P. aeruginosa PAO1, particularly as they apply to QS and virulence. DADS at 1.28 mg/mL did not affect P. aeruginosa PAO1 growth, although it decreased elastase and pyocyanin production, biofilm formation, and swarming motility. Each of these phenomena is regulated by the three QS systems of P. aeruginosa PAO1 (las, rhl, and pqs). Real-time q-PCR revealed that DADS down-regulated the transcription levels of several important QS genes (lasI, lasR, rhlI, rhlR, pqsA, and pqsR) in the three systems. Furthermore, the transcription levels of QS-regulated virulence genes were also down-regulated. The lasB gene, encoding LasB elastase, is co-regulated by the las, rhl, and pqs systems, and thus the down-regulation of genes across the three systems further down-regulated lasB. Additionally, phzM (encoding pyocyanin), pslB (responsible for the production of a biofilm matrix polysaccharide), and chiC (encoding chitinase) were positively activated by LasR, and a decrease in lasR transcription further down-regulated the transcription of phzM, pslB, and chiC. Hence, DADS inhibits P. aeruginosa PAO1 virulence factors by inactivating the transcription of key genes across three different QS systems.