Pseudomonas Aeruginosa Research Articles

A Comparative Study on the Antibiotics’ Resistance in Nosocomial and Environmental Isolates of Pseudomonas Aeruginosa in Aden, Yemen, 2023

Introduction: Pseudomonas aeruginosa is a common bacterial pathogen with wide spread distribution in health care settings. It is a multidrug resistant pathogen recognized for its ubiquity and intrinsically advanced antibiotic resistance mechanisms. This study aims to find out the isolation rate and to determine antimicrobial susceptibility patterns, and level of multidrug resistance from nosocomial and environmental isolates of P. aeruginosa. Methods: A cross-sectional study was carried out over a 6-months period from September 2022 to February 2023 and a total of 217 samples were enrolled which included 130 different clinical specimens from patients with nosocomial infections and 87 samples of hospital environment at different departments in four hospitals in Aden governorate, Yemen. The isolates were identified by biochemical tests as well as the susceptibility patterns which were tested by 22 types of antibiotics. All data were analyzed using SPSS statistics version 22 with a significance level of P<0.05. Results: The P. aeruginosa were isolated from 23.1% of clinical specimens and 32.2% from environmental samples. The statistical analysis showed no statistically significant difference between clinical and environmental samples in prevalence (P˃0.05). The most effective antibiotic against clinical isolates was Pipracillin/tazobactam with only 6.7% resistance value. In contrast, the most effective antibiotic against environmental strains was ciprofloxacin without any resistance value. The resistance to other antibiotics was found to be high or completely resistant. Ninety percent of clinical P. aeruginosa isolates and 96.4% of environmental isolates were multidrug resistant.

Preventive nasal administration of flagellin restores antimicrobial effect of gentamicin and protects against a multidrug-resistant strain of Pseudomonas aeruginosa.

The increasing prevalence of multidrug-resistant Pseudomonas aeruginosa (PA) is a significant concern for chronic respiratory disease exacerbations. Host-directed drugs, such as flagellin, an agonist of toll-like receptor 5 (TLR5), have emerged as a promising solution. In this study, we evaluated the prophylactic intranasal administration of flagellin against a multidrug-resistant strain of PA (PAMDR) in mice and assessed the possible synergy with the antibiotic gentamicin (GNT). The results indicated that flagellin treatment before infection decreased bacterial load in the lungs, likely due to an increase in neutrophil recruitment, and reduced signs of inflammation, including proinflammatory cytokines. The combination of flagellin and GNT showed a synergistic effect, decreasing even more the bacterial load and increasing mice survival rates, in comparison to mice pre-treated only with flagellin. These findings suggest that preventive nasal administration of flagellin could restore the effect of GNT against MDR strains of PA, paving the way for the use of flagellin in vulnerable patients with chronic respiratory diseases.

Comparative genomic analysis of Pseudomonas aeruginosa strains susceptible and resistant to carbapenems and aztreonam isolated from patients with healthcare-associated infections in a Mexican hospital.

Pseudomonas aeruginosa (PA) is an important opportunistic pathogen that causes different infections on immunocompromised patients. Within PA accessory genome, differences in virulence, antibiotic resistance and biofilm formation have been described between strains, leading to the emergence of multidrug-resistant strains. The genome sequences of 17 strains isolated from patients with healthcare-associated infections in a Mexican hospital were genomically and phylogenetically analyzed and antibiotic resistance genes, virulence genes, and biofilm formation genes were detected. Fifteen of the 17 strains were resistant to at least two of the carbapenems meropenem, imipenem, and the monobactam aztreonam. The antibiotic resistance (mexA, mexB, and oprM) and the biofilm formation (pslA and pslD) genes were detected in all strains. Differences were found between strains in accessory genome size. The strains had different sequence types, and seven strains had sequence types associated with global high risk epidemic PA clones. All strains were represented in two groups among PA global strains. In the 17 strains, horizontally acquired resistance genes to aminoglycosides and beta-lactams were found, mainly, and between 230 and 240 genes that encode virulence factors. The strains under study were variable in terms of their accessory genome, antibiotic resistance, and virulence genes. With these characteristics, we provide information about the genomic diversity of clinically relevant PA strains.

14-Year Epidemiologic study of Pseudomonas aeruginosa bloodstream infection incidence and resistance in the Veterans Health Administration system, 2009-2022.

Multidrug resistant Pseudomonas aeruginosa (PA) represents a serious threat to hospitalized patients. Characterizing the incidence of PA infection and degree of resistance can inform empiric treatment and preventative measures. We sought to describe trends in incidence and resistance characteristics of PA bloodstream infections (BSI) observed within the Veterans Health Administration (VHA) system and identify factors contributing to higher observed mortality within this population. We characterized demographic and clinical features of unique patients among the VHA population presenting with their first episode of PA-BSI between 2009 and 2022 and summarized trends related to mortality and resistance phenotype based on year and geographical location. We additionally used logistic regression analysis to identify predictors of 30-day mortality among this cohort. We identified 8039 PA-BSIs during the study period, 32.7% of which were hospital onset. Annual PA-BSI cases decreased by 35.8%, and resistance among all antimicrobial classes decreased during the study period, while the proportion of patients receiving early active treatment based on susceptibility testing results increased. Average 30-day mortality rate was 23.3%. Higher Charlson Comorbidity Index, higher mAPACHE score, VHA facility complexity 1b and hospital-onset cases were associated with higher mortality, and early active treatment was associated with lower mortality. PA-BSI resistance decreased across the VHA system during the study period. Further investigation of antimicrobial stewardship measures possibly contributing to the observed decreased resistance in this cohort and identification of measures to improve on the high mortality associated with PA-BSI in the VHA population is warranted.

Isolation of Pseudomonas Aeruginosa and Studying their Resistance and Pyocyanin Production.

Isolation of Pseudomonas Aeruginosa and Studying their Resistance and Pyocyanin Production.

Antibacterial Activity of the Leaves of Colocasia esculenta Linn

The purpose of the investigation was to see if the leaves of Colocasia esculenta Linn were antibacterial. Taro is a plant whose tubers are commonly consumed by Indonesians. Taro leaves, in addition to tubers, can be used as an alternate medication. As a result of their antibacterial qualities. The content Secondary metabolites found in taro leaves have the ability to stop dangerous microorganisms from growing, including Staphylococcus aureus and Pseudomonas Aeruginosa. The method used in this research is to use taro leaf extract, which is divided into various concentration variations. Taro leaf extract is made using hydroalcoholic solvents. The results showed that each concentration showed an antibacterial ability to inhibit the growth of pathogenic bacteria. The higher the concentration of taro leaf extract used, the greater its ability to inhibit the growth of bacteria. This study utilised taro leaf extract, which was separated into various concentrations. variants. Using an hydroalcoholic solvent to extract taro leaves at the time. The findings revealed that each concentration had a different effect and exhibited antibacterial properties by reducing the growth of harmful bacteria proliferation. The higher the content of taro leaf extract, the better. The more it's used, the more it'll be able to stop bacteria from growing. A hydroalcoholic extract of Colocasia esculenta was found to have antibacterial activity against S. Aureus, P. Aeruginosa, and others in our research.

Evaluation of Staphylococcus Aureus and Pseudomonas Aeruginosa in Saliva of Patients with Acute Myeloid Leukemia.

Patients with leukemia are prone to infectious and often life-threatening complications. Evidence suggests that a specific oral microbiota may contribute to septicemia, which can delay antineoplastic treatment, compromise treatment efficacy, or even endanger patients' lives. This study investigated the prevalence of Staphylococcus aureus and Pseudomonas aeruginosa in the saliva of patients with acute myeloid leukemia who were candidates for bone marrow transplantation. This cross-sectional study was conducted in 2019 in the Hematology-Oncology Department of Namazi Hospital, Shiraz University of Medical Sciences. The study included 28 patients with acute myeloid leukemia eligible for bone marrow transplantation as the case group and age- and sex-matched healthy individuals as the control group. Unstimulated saliva samples were collected to determine the frequency of Staphylococcus aureus and Pseudomonas aeruginosa. Data were analyzed using SPSS version 18, the chi-square test, and the independent t-test. In the patients with acute myeloid leukemia, 26 (86%) were positive for Staph-ylococcus aureus and 18 (60%) were positive for Pseudomonas aeruginosa. In the healthy group, 11 (22.9%) were positive for Staphylococcus aureus and 3 (6.2%) were positive for Pseudomonas aeruginosa. The frequency of Pseudomonas aeruginosa and Staphylococcus aureus in the saliva samples of patients with acute myeloid leukemia was significantly higher than in the healthy control subjects (p value < 0.05). Chi-square test showed no significant association between age and the frequency of bacteria (p value= 0.27). In the current study, the frequency of Staphylococcus aureus and Pseudomonas aeruginosa in the saliva of patients with acute myeloid leukemia was higher than in the healthy control group.

Characterization of the Outer Membrane Vesicles of Pseudomonas aeruginosa Exhibiting Growth Inhibition against Acinetobacter baumannii.

We investigated the Pseudomonas aeruginosa (PA) outer membrane vesicles (OMVs) and their effect on Acinetobacter baumannii (AB) growth in vitro. The inhibitory effects of PA on AB were assessed using a cross-streak assay. The OMVs were extracted through high-speed centrifugation, tangential flow filtration, and ultracentrifugation and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), transmission electron microscopy (TEM), and nanoparticle tracking assays (NTAs). Proteomic analysis was conducted to compare the OMVs of different PA strains. PA022 exhibited more pronounced inhibition of AB growth compared with PA ATCC 27853. TEM confirmed the presence of OMVs in both PA022 and PA ATCC 27853, revealing phospholipid bilayer structures. The NTA revealed similar sizes and concentrations. Proteomic analysis identified 623 and 538 proteins in PA022 and PA ATCC 27853 OMVs, respectively, with significant proportions of the outer membrane and extracellular proteins, respectively. Importantly, PA022 OMVs contained six known virulence factors and motility-associated proteins. This study revealed the unique characteristics of PA OMVs and their inhibitory effects on AB growth, shedding light on their role in bacterial interactions. Proteomic analysis provides valuable insights into potential pathogenic functions and therapeutic applications against bacterial infections.

The Potentiation Activity of Azithromycin in Combination with Colistin or Levofloxacin Against Pseudomonas aeruginosa Biofilm Infection.

Pseudomonas aeruginosa (PA) often displays drug resistance and biofilm-mediated adaptability. Here, we aimed to evaluate the antibiofilm efficacy of azithromycin-based combination regimens. Minimum inhibitory concentrations (MICs), minimal biofilm eradication concentrations (MBECs), and MBEC-combination of azithromycin, colistin, amikacin, and levofloxacin to bioluminescent strain PAO1 and carbapenem-resistant PAO1 (CRPAO1) were assessed. An animal biofilm infection model was established and detected using a live animal bio-photonic imaging system. In vitro, PAO1 and CRPAO1 were susceptible to colistin, amikacin, and levofloxacin, while they were unsusceptible to azithromycin. The combinations based on azithromycin have no synergistic effect on biofilm in vitro. In vivo, azithromycin plus colistin or levofloxacin could shorten the PAO1 biofilm eradication time, which totally eradicates the biofilm in all mice on the 8th or 6th day, while monotherapy only eradicate biofilm in 70% or 80% mice on the 8th day. For CRPAO1 biofilm, only azithromycin-colistin combination and colistin monotherapy eradicated the bacteria in 60% and 40% of mice at the 6th day. Azithromycin-based combinations containing levofloxacin or colistin had no synergistic effect in vitro, and they are promising for clinical applications due to the good synergistic activity against PAO1 biofilms in vivo.

Molecular Identification of lasB gene in Pseudomonas Aeruginosa Isolated From Patients With Urinary Tract Infection

Molecular Identification of lasB gene in Pseudomonas Aeruginosa Isolated From Patients With Urinary Tract Infection

Genomic epidemiology and ceftazidime-avibactam high-level resistance mechanisms of Pseudomonas aeruginosa in China from 2010 to 2022

ABSTRACT Ceftazidime-avibactam (CZA) resistance is a huge threat in the clinic; however, the underlying mechanism responsible for high-level CZA resistance in Pseudomonas aeruginosa (PA) isolates remains unknown. In this study, a total of 5,763 P. aeruginosa isolates were collected from 2010 to 2022 to investigate the ceftazidime-avibactam (CZA) high-level resistance mechanisms of Pseudomonas aeruginosa (PA) isolates in China. Fifty-six PER-producing isolates were identified, including 50 isolates carrying bla PER-1 in PA, and 6 isolates carrying bla PER-4. Of these, 82.1% (46/56) were classified as DTR-PA isolates, and 76.79% (43/56) were resistant to CZA. Importantly, bla PER-1 and bla PER-4 overexpression led to 16-fold and >1024-fold increases in the MICs of CZA, respectively. WGS revealed that the bla PER-1 gene was located in two different transferable IncP-2-type plasmids and chromosomes, whereas bla PER-4 was found only on chromosomes and was carried by a class 1 integron embedded in a Tn6485-like transposon. Overexpression of efflux pumps may be associated with high-level CZA resistance in bla PER-1-positive strains. Kinetic parameter analysis revealed that PER-4 exhibited a similar kcat/Km with ceftazidime and a high (∼3359-fold) IC50 value with avibactam compared to PER-1. Our study found that overexpression of PER-1 combined with enhanced efflux pump expression and the low affinity of PER-4 for avibactam contributes to high-level resistance to CZA. Additionally, the Tn6485-like transposon plays a significant role in disseminating bla PER. Urgent active surveillance is required to prevent the further spread of high-level CZA resistance in DTR-PA isolates.

Molecular Identification and Detection of Virulence Genes Among Pseudomonas Aeruginosa Isolated from Burns Infections

Objective: Virulence factors are substances produced by pathogenic Pseudomonas aeruginosa that contribute significantly to the etiology of disease. These virulence factors are encoded by virulence genes found on the Pseudomonas aeruginosa chromosome. Methods: Between July 2021 and June 2022, 71 Pseudomonas aeruginosa isolates were identified from burn wounds at the Burn and Plastic Surgery Hospital in Duhok, Iraq. The lasB and toxA genes were identified using Polymerase Chain Reaction (PCR). Results: Only 26.36% (29/71) of the 71 Pseudomonas aeruginosa isolates were found in males, whereas 38.18% (42/71) were found in females. Furthermore, 76.06% (54/71) of the isolates were multidrug resistant. They demonstrated greater resistance to piperacillin, 98.59% resistance rates. Among the isolates analyzed, 35 (64.81%) were positive for toxA and 27 (50%) were positive for lasB genes. Conclusion: Due to the limited number of effective medications against this bacteria that are currently available, all isolates must undergo antimicrobial susceptibility testing. By doing this, you can help manage the treatment plan and stop the emergence of resistance in burn units.

The O-glycan is essential for the induction of protective antibodies against lethal infection by flagella A-bearing Pseudomonas aeruginosa.

To address the problem of increased antimicrobial resistance, we developed a glycoconjugate vaccine comprised of O-polysaccharides (OPS) of the four most prevalent serotypes of Klebsiella pneumoniae (KP) linked to recombinant flagellin types A and B (rFlaA and rFlaB) of Pseudomonas aeruginosa (PA). Flagellin is the major subunit of the flagellar filament. Flagella A and B, essential virulence factors for PA, are glycosylated with different glycans. We previously reported that while both rFlaA and rFlaB were highly immunogenic, only the rFlaB antisera reduced PA motility and protected mice from lethal PA infection in a mouse model of thermal injury. Since recombinant flagellin is not glycosylated, we examined the possibility that the glycan on native FlaA (nFlaA) might be critical to functional immune responses. We compared the ability of nFlaA to that of native, deglycosylated FlaA (dnFlaA) to induce functionally active antisera. O glycan was removed from nFlaA with trifluoromethanesulfonic acid. Despite the similar high-titered anti-FlaA antibody levels elicited by nFlaA, rFlaA, and dnFlaA, only the nFlaA antisera inhibited PA motility and protected mice following lethal intraperitoneal bacterial challenge. Both the protective efficacy and carrier protein function of nFlaA were retained when conjugated to KP O1 OPS. We conclude that unlike the case with FlaB O glycan, the FlaA glycan is an important epitope for the induction of functionally active anti-FlaA antibodies.

Structural dynamics and anti-biofilm screening of novel imidazole derivative to explore their anti-biofilm inhibition mechanism against Pseudomonas Aeruginosa

The biofilm formation is still prevalent mechanism of developing the drug resistance in the Pseudomonas aeruginosa, gram-negative bacteria, known for its major role in nosocomial, ventilator-associated pneumonia (VAP), lung infections and catheter-associated urinary tract infections. As best of our knowledge, current study first time reports the most potent inhibitors of LasR, a transcriptional activator of biofilm and virulence regulating genes in, Pseudomonas aeruginosa LasR, utilizing newly functionalized imidazoles (5a-d), synthesized via 1,3-dipolar cycloaddition using click approach. The synthesized ligands were characterized through Mass Spectrometry and 1H NMR. The binding potency and mode of biding of ligands. Quantum Mechanical(QM) methods were utilized to investigate the electronic basis, HOMO/LUMO and dipole moment of the geometry of the ligands for their binding potency. Dynamics cross correlation matrix (DCCMs) and protein surface analysis were further utilized to explore the structural dynamics of the protein. Free energy of binding of ligands and protein were further estimated using Molecular Mechanical Energies with the Poisson–Boltzmann surface area (MMPBSA) method. Molecular Docking studies revealed significant negative binding energies (5a − 10.33, 5b −10.09, 5c − 10.11, and 5d −8.33 KJ/mol). HOMO/LUMO and potential energy surface map estimation showed the ligands(5a) with lower energy gaps and larger dipole moments had relatively larger binding potency. The significant change in the structural dynamics of LasR protein due to complex formation with newlyfunctionalized imidazoles ligands. Hydrogen bond surface analysis followed by MMPBSA calculations of free energy of binding further complemented the Molecular docking revelations showing the specifically ligand (5a) having the relatively higher energy of binding(-65.22kj/mol). Communicated by Ramaswamy H. Sarma

Incidence, Risk Factors and Microbiological Profile of Ventilator Associated Pneumonia Patients in ICU in Tertiary Care Hospital

Background: VAP, or ventilator-associated pneumonia, is one of the most common ICU-acquired diseases and a significant cause of mortality among Intensive Care Unit patients. Infectious illnesses are currently underestimated in the South Asian Region, which has limited health resources.&#x0D; Objective: To examine the incidence of VAP, risk factors associated and the microbiological profile in ICU patients in tertiary care hospitals.&#x0D; Methods: A total of 114 patients under mechanical who satisfied all inclusion criteria were selected. Detailed history, investigations were undertaken. The diagnosis of VAP was made according to clinical and laboratory findings (as per CDC criteria) and incidence was derived from the number of patients developing VAP out of the total number of patients on ventilatory support in ICU.&#x0D; Results: We included 114 patients in our study. Out of 114 patients, the majority were above 70 years age group Mean age of study population was 61.29±13.42 years. Out of 114, 80 patients i.e. 70.2% were males and 34(29.8%) were females. Male: female ratio was 2.3:1. Klebsiella Pneumonia was a commonly observed organism in cultures i.e. 30.7%, followed by Pseudomonas Aeruginosa in 27.2% and Acinetobacter Baumani in 19.3%. Antibiotic sensitivity pattern of Klebsiella Pneumonia showed resistance to Carbapenemase in 20(57.1%) cases and to ESBL in 15(42.9%) cases. Death rate in our study was 17.5%&#x0D; Conclusion: The outcome of VAP depends on rapid identification of the causative microorganism. Empirical therapy based on knowledge of the most prevalent microorganisms and their resistance pattern has an impact on lowering morbidity and mortality, shortening the length of hospital stay, lowering of treatment expenses, and prevents the development of MDR bacteria in patients with VAP.

CF Lung Disease - a German S3 Guideline: Pseudomonas aeruginosa

Cystic Fibrosis (CF) is the most common autosomal recessive genetic multisystemic disease. In Germany, it affects at least 8000 people. The disease is caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene leading to dysfunction of CFTR, a transmembrane chloride channel. This defect causes insufficient hydration of the airway epithelial lining fluid which leads to reduction of the mucociliary clearance.Even if highly effective, CFTR modulator therapy has been available for some years and people with CF are getting much older than before, recurrent and chronic infections of the airways as well as pulmonary exacerbations still occur. In adult CF life, Pseudomonas aeruginosa (PA) is the most relevant pathogen in colonisation and chronic infection of the lung, leading to further loss of lung function. There are many possibilities to treat PA-infection.This is a S3-clinical guideline which implements a definition for chronic PA-infection and demonstrates evidence-based diagnostic methods and medical treatment in order to give guidance for individual treatment options.

Fluorescence Spectroscopy Based Identification of Pseudomonas Aeruginosa and Escherichia Coli Suspensions.

In this article, Fluorescence spectroscopy has been employed for the identification of Pseudomonas aeruginosa (PA) and Escherichia coli (E. coli) in water suspension. Emission spectra of PA and E. coli suspensions have been acquired by using excitation wavelengths from 270 to 420nm with steps of 10nm to explore their spectral features. It has been found that the emission spectra of tryptophan, tyrosine, NADH and FAD, being the intracellular biomolecules present in both bacteria, can be used as fingerprints for their identification, differentiation and quantification. Both bacterial strains can clearly be differentiated from water and from each other by using λex 270-290nm through spectral analysis and from λex: 300-500nm by applying statistical analysis. Furthermore, calibration curves for different bacterial loads of PA and E. coli suspensions have been produced between colonies forming units per ml (CFUs/ml) the integrated intensities of their emission spectra. CFUs/ml of both bacterial suspensions have been determined through plate count method which was used as cross-reference for the analysis of emission spectra of both bacterial suspensions. These curves may be used to estimate CFU/ml of both PA and E. coli in unknown water suspensions by determining the integrating intensity of their emission spectra.

Effect of Piper Cubeba Extract on Biofim Producing Pseudomonas Aeruginosa Isolated from Clinical Samples

Background: The species of Pseudomonas aeruginosa is a nosocomial bacterium that increases the risk of multidrug-resistant infections, especially in vulnerable patients. The plant Piper cubeba, commonly referred to as cubeb or tailed pepper, it is specifically cultivated for its fruit and essential oil. The plant belongs to the genus Piper. The study aims at assessing the effectiveness of Piper cubeba extract against different P. aeruginosa strains that could produce biofilm and carry blaIMP gene. Method: Isolates from 85 samples (17 sputum, 40 urine and 28 diarrhea samples). Collected from Al Nasiriyah Teaching Hospital during the period of December 2021 to March 2022. Samples were cultivated using routine cultivation methods, catalase test, oxidase reaction, and the Api20E system were performed to identify P. aeruginosa. Results: Out of a total of 17 isolated samples of Pseudomonas aeruginosa, 3 (17.64%) were from sputum, 6(35.29%) from urine, and 8 (47.05%) diarrhea samples. Out of 17 isolates 6 were sensitive in stool isolates 4 isolates were moderate sensitive and 7 isolates were resistance. Conclusion at concentrations of 25, 50, 75, and 100 mg/mL for Piper cubeba, respectively, the greatest MBC of plant extracts was noted. Also, all the isolates were capable of producing a biofilm by using presterilized 96-well polystyrene microtiter plates. Out of 17 isolates, 9 had a potent biofilm ability and the remaining 7 were moderate biofilm producers. Additionally, 7 of the isolates (41.17%) carried the blaIMP gene. Conclusion: Piper cubeba extract has potential as an antimicrobial agent against both sensitive and moderately resistant strains of Pseudomonas aeruginosa. This antimicrobial effect becomes more pronounced with an increase in the concentration of the extract. Additionally, Pseudomonas aeruginosa that produce biofilms tend to consistently produce more Metallo-beta-lactamase (MBL), which can further contribute to antibiotic resistance.

Fever-like temperature impacts on Staphylococcus aureus and Pseudomonas aeruginosa interaction, physiology, and virulence both in vitro and in vivo

BackgroundStaphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) cause a wide variety of bacterial infections and coinfections, showing a complex interaction that involves the production of different metabolites and metabolic changes. Temperature is a key factor for bacterial survival and virulence and within the host, bacteria could be exposed to an increment in temperature during fever development. We analyzed the previously unexplored effect of fever-like temperatures (39 °C) on S. aureus USA300 and P. aeruginosa PAO1 microaerobic mono- and co-cultures compared with 37 °C, by using RNAseq and physiological assays including in vivo experiments.ResultsIn general terms both temperature and co-culturing had a strong impact on both PA and SA with the exception of the temperature response of monocultured PA. We studied metabolic and virulence changes in both species. Altered metabolic features at 39 °C included arginine biosynthesis and the periplasmic glucose oxidation in S. aureus and P. aeruginosa monocultures respectively. When PA co-cultures were exposed at 39 °C, they upregulated ethanol oxidation-related genes along with an increment in organic acid accumulation. Regarding virulence factors, monocultured SA showed an increase in the mRNA expression of the agr operon and hld, pmsα, and pmsβ genes at 39 °C. Supported by mRNA data, we performed physiological experiments and detected and increment in hemolysis, staphyloxantin production, and a decrease in biofilm formation at 39 °C. On the side of PA monocultures, we observed an increase in extracellular lipase and protease and biofilm formation at 39 °C along with a decrease in the motility in correlation with changes observed at mRNA abundance. Additionally, we assessed host–pathogen interaction both in vitro and in vivo. S. aureus monocultured at 39οC showed a decrease in cellular invasion and an increase in IL-8—but not in IL-6—production by A549 cell line. PA also decreased its cellular invasion when monocultured at 39 °C and did not induce any change in IL-8 or IL-6 production. PA strongly increased cellular invasion when co-cultured at 37 and 39 °C. Finally, we observed increased lethality in mice intranasally inoculated with S. aureus monocultures pre-incubated at 39 °C and even higher levels when inoculated with co-cultures. The bacterial burden for P. aeruginosa was higher in liver when the mice were infected with co-cultures previously incubated at 39 °C comparing with 37 °C.ConclusionsOur results highlight a relevant change in the virulence of bacterial opportunistic pathogens exposed to fever-like temperatures in presence of competitors, opening new questions related to bacteria-bacteria and host–pathogen interactions and coevolution.

Cystic Fibrosis Mice Are Highly Susceptible to Repeated Acute Pseudomonas aeruginosa Pneumonia after Intranasal Inoculation.

Cystic fibrosis (CF) is a genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) that controls chloride current. A number of different CFTR transgenic mouse lines have been developed and subjected to both acute and chronic infection models. However, prior studies showed no substantial differences in bacterial clearance between CF and non-CF mice after single inoculations. Here, using F508del transgenic CF mice, we examined the role of repeated acute Pseudomonas aeruginosa (PA) infection, with the second inoculation 7 days after the first. We found that CF mice were more susceptible to PA infection than non-CF mice following the second inoculation, with non-CF mice showing better neutrophil recruitment and effector functions. We further investigated the characteristics of lung immune cells using single-cell RNA sequencing, finding that non-CF lung neutrophils had more prominent upregulation of adhesion molecules including intercellular adhesion molecule-1 (ICAM-1) compared to CF lung neutrophils. Although people with CF are often colonized with bacteria and have high numbers of neutrophils in the airways during chronic infection, these data suggest that CF neutrophils have deficient effector functions in the setting of repeated acute infection.