Pseudomonas Aeruginosa Isolates Research Articles

Identification of Bioactive Compounds of Streptomyces spp. Isolated from Qom Lake Sediments and Evaluation of its Antimicrobial Activity against Pseudomonas aeruginosa

Background: Marine sediments are rich sources for isolating active secondary metabolites from microorganisms. Among the microorganisms, Actinomycetes are highly important due to the production of various chemical compounds in a wide range of biological activities, such as antibacterial activity. Streptomyces is the most important genera in the family of Actinomycetes. As a member of this group, it has great potential in the production of secondary metabolites such as antibiotics, enzymes, herbicides, anti-carcinogenic, and other useful compounds. Objective: This study aims to identify bioactive compounds of Streptomyces isolated from sediments of the Salt Lake of Qom and to study their antimicrobial properties against standard strains of Pseudomonas aeruginosa. Methods: In this study, 20 samples were collected from a depth of 5 to 15-20 cm of sediment in the Salt Lake of Qom. Pure cultivations were then provided from these samples. This study used starch casein agar (SCA) to isolate streptomyces, and 35 Streptomyces were isolated. The disc diffusion method was used to explore the antimicrobial properties of Streptomyces against clinical strains of Pseudomonas aeruginosa and strains standard of Pseudomonas aeruginosa PTCC 1310. Results: Seven strains, including SCA3 SCB1, SCB4, SCB8, SCC15, SCC18, and SCC28 strains, had antimicrobial properties. In this study, the results show that SCC15 with the halo diameter of 17, 17, 15, and 19 contains the best antibacterial properties against clinical strains 1, 2 and 3 of Pseudomonas aeruginosa and Pseudomonas aeruginosa PTCC 1310. among the 16 peaks observed by GC/MS to identify bioactive compounds of Streptomyces, it was found that Bis (2-ethyl hexyl) phthalate, with 69.06 percent, had the highest peak production, which reflects the importance of phthalates in microbial activities. Conclusion: According to the results, the Salt Lake of Qom was one of the sources of Streptomyces. In addition, the isolated Streptomyces had antimicrobial properties against Pseudomonas aeruginosa isolates. It was also found that phthalate was the most bioactive substance of Streptomyces isolated.

Epidemiology of healthcare-associated Pseudomonas aeruginosa in intensive care units: are sink drains to blame?

Pseudomonas aeruginosa (PA) is a common cause of healthcare-associated infections (PA-HAI) in the intensive care unit (ICU). We aimed to describe the epidemiology of PA-HAI in ICUs in Ontario, Canada, and determine whether we could identify episodes of sink-to-patient PA transmission. This was a prospective cohort study of patients in six ICUs from 2018-2019, with retrieval of PA clinical isolates, and PA-screening of antimicrobial resistant organism surveillance rectal swabs, and of sink drain, air, and faucet samples. All PA isolates underwent whole genome sequencing. PA-HAI was defined using US National Healthcare Safety Network criteria. ICU-acquired PA was defined as PA isolated from specimens obtained >48 hours after ICU admission in those with prior negative rectal swabs. Sink-to-patient PA transmission was defined as ICU-acquired PA with close genomic relationship to isolate(s) previously recovered from sinks in a room/bedspace occupied 3-14 days prior to the relevant patient isolate. Over ten months, 72 PA-HAI occurred among 60/4263 admissions. The rate of PA-HAI was 2.40 per 1000 patient-ICU days; higher in patients who were PA-colonized on admission. PA-HAI was associated with longer stay (median 26 vs 3 days uninfected, p<0.001) and contributed to death in 22/60 cases (36.7%). Fifty-eight admissions with ICU-acquired PA were identified, contributing 35/72 (48.6%) PA-HAI. Four patients with five PA-HAI (6.9%) had closely related isolates previously recovered from their room/bedspace sinks. Nearly half of PA causing HAI appeared to be acquired in ICUs, and 7% of PA-HAI were associated with sink-to-patient transmission. Sinks may be an underrecognized reservoir for HAIs.

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&lt;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.

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

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

A phase 4 multicentre, 2×2 factorial randomised, double-blind, placebo-controlled trial to investigate the efficacy and safety of tobramycin inhalation solution for Pseudomonas aeruginosa eradication in bronchiectasis: ERASE.

Chronic Pseudomonas aeruginosa (PA) infection significantly contributes to morbidity and mortality in bronchiectasis patients. Initiating antibiotics early may lead to the eradication of PA. Here we outline the design of a trial (ERASE; NCT06093191) assessing the efficacy and safety of inhaled tobramycin, alone or with oral ciprofloxacin, in bronchiectasis patients with a new isolation of PA. This multicentre, 2×2 factorial randomised, double-blind, placebo-controlled, parallel-group trial includes a 2-week screening period, a 12-week treatment phase (with a combination of ciprofloxacin or a placebo at initial 2 weeks) and a 24-week follow-up. 364 adults with bronchiectasis and a new PA isolation will be randomly assigned to one of four groups: placebo (inhaled saline and ciprofloxacin placebo twice daily), ciprofloxacin alone (750 mg ciprofloxacin and inhaled saline twice daily), inhaled tobramycin alone (inhaled 300 mg tobramycin and ciprofloxacin placebo twice daily) or a combination of both drugs (inhaled 300 mg tobramycin and 750 mg ciprofloxacin twice daily). The primary objective of this study is to assess the proportion of patients successfully eradicating PA in each group by the end of the study. Efficacy will be evaluated based on the eradication rate of PA at other time points (12, 24 and 36 weeks), the occurrence of exacerbations and hospitalisations, time to first pulmonary exacerbations, patient-reported outcomes, symptom measures, pulmonary function tests and the cost of hospitalisations. To date no randomised trial has evaluated the benefit of different PA eradication strategies in bronchiectasis patients. The ERASE trial will therefore generate crucial data to inform future clinical guidelines.

The Inhibitory Effect of Conocarpus Lancifolius Leaf Extract on Protease Produced by Clinical Pseudomonas Aeruginosa Isolate

The study was aimed at inhibiting the protease produced by Pseudomonas aeruginosa using an 80% alcoholic extract of Conocarpus lancifolius leaves. A total of 146 isolates of P. aeruginosa that were isolated and identified by microscopic and biochemical tests were 51 isolates submitted to primary and secondary screening techniques in order to choose the qualified P. aeruginosa isolate for protease synthesis. Among these isolates, forty-seven isolates showed hydrolysis zones on skim milk media (primary screening); six isolates were chosen for secondary screening. The result revealed that P. aeruginosa P51 had the highest ability to produce the enzyme, with a specific activity of 15.9 U/mg protein. In addition, the study included extracting the leaves of C. lancifolius using 80% ethanolic alcohol and conducting the GC-MC assay and the HPLC assay of the plant extract. The results revealed a significantly decreased specific activity of protease from 15.9 to 1.2 U/mg after treatment with 0.8 µg/ml of alcoholic extract of C. lancifolius leaves.

The Impact of Pseudomonas aeruginosa Infection in Adult Cystic Fibrosis Patients-A Single Polish Centre Study.

Pseudomonas aeruginosa (PA) is one of the most predominant pathogens of lung infections, often causing exacerbations in adult patients with cystic fibrosis (CF). Microbiological characterization of 74 PA isolates and to evaluate the correlations between the bacterial features and 44 adult Polish CF cohort clinical parameters. The most common variant in the CF transmembrane conductance regulator (CFTR) gene was F508del (76.3%), followed by 3849+10kbC>T (26.3%). A total of 39.4% of the PA isolates showed multiple resistances. In patients with parameters pointing to a decline in lung function, there was a statistically significant moderate correlation with β-lactam resistance and a weak correlation between hospital frequency and colistin resistance. The mucoidity did not correlate with the biofilm formation ability, which showed 41.9% of the isolates. Proteolytic activity, observed in 60.8% of the clinical isolates, was weakly associated with motility detected in 78.4% of the strains. The genetic profiles of the PA were highly heterogeneous, and a weak positive correlation was established between cluster group and biofilm formation. The findings suggest that there is a high variety in P. aeruginosa populations in adult CF patients. There is a need to monitor PA strains in groups of patients with cystic fibrosis, in particular, in terms of the occurrence of antibiotic resistance related to a decline in lung function.

Discovery of highly neutralizing human antibodies targeting Pseudomonas aeruginosa

Drug-resistant Pseudomonas aeruginosa (PA) poses an emerging threat to human health with urgent need for alternative therapeutic approaches. Here, we deciphered the B cell and antibody response to the virulence-associated type III secretion system (T3SS) in a cohort of patients chronically infected with PA. Single-cell analytics revealed a diverse B cell receptor repertoire directed against the T3SS needle-tip protein PcrV, enabling the production of monoclonal antibodies (mAbs) abrogating T3SS-mediated cytotoxicity. Mechanistic studies involving cryoelectron microscopy identified a surface-exposed C-terminal PcrV epitope as the target of highly neutralizing mAbs with broad activity against drug-resistant PA isolates. These anti-PcrV mAbs were as effective as treatment with conventional antibiotics invivo. Our study reveals that chronically infected patients represent a source of neutralizing antibodies, which can be exploited as therapeutics against PA.

Fibroblast Growth Factor 23 Signaling Does Not Increase Inflammation from Pseudomonas aeruginosa Infection in the Cystic Fibrosis Bronchial Epithelium.

Background and Objectives: Chronic inflammation due to Pseudomonas aeruginosa (PA) infection in people with cystic fibrosis (CF) remains a concerning issue in the wake of modulator therapy initiation. Given the perpetuating cycle of colonization, infection, chronic inflammation, and recurrent injury to the lung, there are increases in the risk for mortality in the CF population. We have previously shown that fibroblast growth factor (FGF) 23 can exaggerate transforming growth factor (TGF) beta-mediated bronchial inflammation in CF. Our study aims to shed light on whether FGF23 signaling also plays a role in PA infection of the CF bronchial epithelium. Materials and Methods: CF bronchial epithelial cells were pretreated with FGF23 or inhibitors for FGF receptors (FGFR) and then infected with different PA isolates. After infection, immunoblot analyses were performed on these samples to assess the levels of phosphorylated phospholipase C gamma (PLCγ), total PLCγ, phosphorylated extracellular signal-regulated kinase (ERK), and total ERK. Additionally, the expression of FGFRs and interleukins at the transcript level (RT-qPCR), as well as production of interleukin (IL)-6 and IL-8 at the protein level (ELISA) were determined. Results: Although there were decreases in isoform-specific FGFRs with increases in interleukins at the mRNA level as well as phosphorylated PLCγ and the production of IL-8 protein with PA infection, treatment with FGF23 or FGFR blockade did not alter downstream targets such as IL-6 and IL-8. Conclusions: FGF23 signaling does not seem to modulate the PA-mediated inflammatory response of the CF bronchial epithelium.

Antimicrobial Resistance, Genetic Lineages, and Biofilm Formation in Pseudomonas aeruginosa Isolated from Human Infections: An Emerging One Health Concern.

Pseudomonas aeruginosa (PA) is a leading nosocomial pathogen and has great versatility due to a complex interplay between antimicrobial resistance and virulence factors. PA has also turned into one the most relevant model organisms for the study of biofilm-associated infections. The objective of the study focused on analyzing the antimicrobial susceptibility, resistance genes, virulence factors, and biofilm formation ability of thirty-two isolates of PA. PA isolates were characterized by the following analyses: susceptibility to 12 antimicrobial agents, the presence of resistance genes and virulence factors in PCR assays, and the quantification of biofilm production as evaluated by two distinct assays. Selected PA isolates were analyzed through multilocus sequence typing (MLST). Thirty PA isolates have a multi-resistant phenotype, and most of the isolates showed high levels of resistance to the tested antibiotics. Carbapenems showed the highest prevalence of resistance. Various virulence factors were detected and, for the quantification of biofilm production, the effectiveness of different methods was assessed. The microtiter plate method showed the highest accuracy and reproducibility for detecting biofilm-producing bacteria. MLST revealed four distinct sequence types (STs) in clinical PA, with three of them considered high-risk clones of PA, namely ST175, ST235, and ST244. These clones are associated with multidrug resistance and are prevalent in hospitals worldwide. Overall, the study highlights the high prevalence of antibiotic resistance, the presence of carbapenemase genes, the diversity of virulence factors, and the importance of biofilm formation in PA clinical isolates. Understanding these factors is crucial for effective infection control measures and the development of targeted treatment strategies.

Antimicrobial Resistance in Pseudomonas aeruginosa before and during the COVID-19 Pandemic.

Pseudomonas aeruginosa (PA) is a major Gram-negative opportunistic pathogen causing several serious acute and chronic infections in the nosocomial and community settings. PA eradication has become increasingly difficult due to its remarkable ability to evade antibiotics. Therefore, epidemiological studies are needed to limit the infection and aim for the correct treatment. The present retrospective study focused on PA presence among samples collected at the San Giovanni di Dio and Ruggi D'Aragona University Hospital in Salerno, Italy; its resistance profile and relative variations over the eight years were analyzed. Bacterial identification and antibiotic susceptibility tests were performed by VITEK® 2. In the 2015-2019 and 2020-2022 timeframes, respectively, 1739 and 1307 isolates of PA were obtained from respiratory samples, wound swabs, urine cultures, cultural swabs, blood, liquor, catheter cultures, vaginal swabs, and others. During 2015-2019, PA strains exhibited low resistance against amikacin (17.2%), gentamicin (25.2%), and cefepime (28.3%); moderate resistance against ceftazidime (34.4%), imipenem (34.6%), and piperacillin/tazobactam (37.7%); and high resistance against ciprofloxacin (42.4%) and levofloxacin (50.6%). Conversely, during the 2020-2022 era, PA showed 11.7, 21.1, 26.9, 32.6, 33.1, 38.7, and 39.8% resistance to amikacin, tobramycin, cefepime, imipenem, ceftazidime, ciprofloxacin, and piperacillin/tazobactam, respectively. An overall resistance-decreasing trend was observed for imipenem and gentamicin during 2015-2019. Instead, a significant increase in resistance was recorded for cefepime, ceftazidime, and imipenem in the second set of years investigated. Monitoring sentinel germs represents a key factor in optimizing empirical therapy to minimize the spread of antimicrobial resistance.

Sniffing Out Pseudomonas Aeruginosa Wound Infections with Vitamin B12: A Simple and Selective Colorimetric Biosensor for Early Diagnosis

Abstract Background The vacuum-assisted closure (VAC) system is a useful tool to promote wound healing. However, due to its occlusive system, the wound is often prone to Pseudomonas aeruginosa (PA) infections. Early detection and initiation of treatment is essential to limit the damage (e.g., saving a skin graft), but the black sponge occludes the wound and prevents its visual assessment leading to delayed diagnosis. Fortunately, each bacterium emits a spectrum of specific volatile organic compounds that can be used for detection. For PA, the signature compound is hydrogen cyanide. Aims We aimed to develop a colorimetric biosensor for “naked-eye” detection of PA that takes advantage of the negative pressure created by the VAC to collect hydrogen cyanide. Methods We used aquocyanocobinamide, a derivative of vitamin B12, as a colorimetric chemosensor of biological cyanide. By binding cyanide, the color of the sensor changes from orange to violet, which can be quantified with UV-VIS spectroscopy. The sensor was delivered onto the carrier material polyvinyl acetate. Its sensitivity was assessed using laboratory strains and clinical isolates of PA in-vitro and on an ex vivo skin model. Results UV-VIS spectroscopy readings of the sensor were calibrated for the cyanide concentration 0-250ppm. Cyanide produced by 30 laboratory and 20 clinical PA isolates were quantified based on the colorimetric changes of the sensor. While the sensor detected all PA strains, it did not falsely react to other wound pathogens such as Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Enterococci, suggesting a high specificity. In a proof-of-principle experiment, the colorimetric change of the sensor was detected by eye after 3 hours incubation with a PA culture. Conclusions The presence of Pseudomonas aeruginosa can be quickly and reliably detected by our vitamin B12-based colorimetric biosensor. Its incorporation inside the VAC-system can allow physicians to detect PA wound infections early on.

Improved engineering of Pseudomonas aeruginosa to study the adaptation of pyoverdine production under intra- or inter- specific bacterial competition

Pseudomonas aeruginosa (PA) is a common cause of chronic infections, particularly feared by cystic fibrosis patients. PA colonizes the lung where it adapts to the local environment, and/or to treatments by drugs. This genotypic and phenotypic adaptation, in turns, influences its interaction with its environment, like bacteria from the microbiota. As an example, to access iron, PA produces and secretes two siderophores, pyoverdine and pyochelin that are iron chelators scavenging iron from the environment and bringing it back into the bacterial cells. Siderophores production depends on the level of iron starvation, on the presence of other bacteria, etc. this latter component being less well investigated. Even if studies on bacterial interactions, and their evolution, have been increasing since several years, we are still facing a lack of tools, for example, to specifically follow the growth of PA isolates in such competitive environments. We thus improved a cloning method to gain time in the cloning steps, to lower the polar effects, and to accurately follow the interactions of any PA isolate with other bacteria. For that, a fluorescent reporter gene was inserted between two genes, the glutamine-fructose-6-phosphate transaminase (glmS) and PA5548. This reporter was efficiently produced either from an inducible or a house-keeping promoter, and its expression did not lead to polar effects.We used this strain to study intra and inter-specific bacterial competitions for iron between different lung pathogens. We thus grew wild-type PA together either with an isogenic PA ΔpvdS variant, that does not produce the most efficient siderophore pyoverdine, or with Klebsiella pneumoniae or Acinetobacter baumanii, two other lung pathogens. We finally monitored the effect of the loss of pvdS on the competition between PA and the other bacterial species. These studies enabled us to differentiate intra from inter specific competitions, both arising in the lung environment, and pinpoint the importance of the bacterial specie for the adaptation of pyoverdine production.

Isolation and characterization of bacteriophages specific to selected equine genital pathogens

Chronic bacterial endometritis is among the major problems in equine reproduction. Streptococcus equi ssp. zooepidemicus (SEZ), Klebsiella pneumoniae (KP), and Pseudomonas aeruginosa (PA) are among the most important pathogens for the condition. Bacteriophages (phages) are the viruses of bacteria, having a species- and strain-specific lytic activity. Due to their bactericidal capacities, phages can be used as an alternative treatment approach for bacterial infections. The study aimed to isolate and characterize phages with lytic activity against Streptococcus equi ssp. zooepidemicus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Phage samples were obtained from manure, uterine lavage fluid and drain water of horse husbandries (n=14). For isolation of phages, bacterial isolates of the equine genital tract (SEZ (n=1), KP (n=1), and PA (n=1)) were inoculated with the phage samples. For purification, bacteriophage plaques were repeatedly cultivated, harvested and filtered. For determining the host-range, the obtained phages were inoculated with bacterial isolates (SEZ (n=37), KP (n=26), and PA (n=33)). In total, 28 bacteriophages were isolated (against SEZ (n=13), KP (n=6), and PA (n=9)). Bacteriolysis was achieved in 32/37 Streptococcus-, 16/26 Klebsiella-, and 14/33 Pseudomonas-isolates. The bacteriophage showing the broadest host range covered 81% of all tested Streptococcus-isolates (30/37). Host ranges of Klebsiella pneumoniae- (9/26) and Pseudomonas aeruginosa-specific bacteriophages (14/33) covered a lower proportion of tested isolates. Seven bacteriophages (SEZ (n=3), KP (n=3), PA (n=1)) were selected according to theirhost ranges and submitted to electron microscopy for further characterization. Electron micrographs revealed that the selected bacteriophages belonged either to the family Demerecviridae (n=1), Myoviridae (n=1), Podoviridae (n=3) or Siphoviridae (n=2), which was confirmed by sequencing. Next, planktonic killing assay was conducted, incubating liquid cultures of Streptococcus equi ssp. zooepidemicus-, Klebsiella pneumoniae- and Pseudomonas aeruginosa-isolates in presence and absence of a specific bacteriophage and monitoring growth by optical density measurements for 24h. Significantly decreased bacterial growth, as determined by comparing the area under the curve (AUC), was observed in presence of 0/3 Streptococcus equi ssp. zooepidemicus-, 1/1 Pseudomonas aeruginosa- and 3/3 Klebsiella pneumoniae-specific phages, using a multiplicity of infection of 1 (MOI1; one phage per host cell). At MOI10 the most effective Streptococcus-phage reduced the AUC by 61%; the most effective Klebsiella-phage resulted in 95% reduction using MOI1 and for the Pseudomonas-phage AUC was reduced by 14% at MOI100. In conclusion, isolation of phages specific to equine uterine pathogens resulted in 28 purified phages. Seven phages were selected and further characterized by efficacy testing, sequencing and electron microscopy. Results of the in vitro host range determination and planktonic killing assay are promising, suggesting further investigations and the development of an alternative treatment approach for uterine infections in mares.

The value of biofilm testing to guide antimicrobial stewardship in chronic respiratory diseases.

Biofilm production is an important yet currently overlooked aspect of diagnostic microbiology that has implications for antimicrobial stewardship. In this study, we aimed to validate and identify additional applications of the BioFilm Ring Test® (BRT) for Pseudomonas aeruginosa (PA) isolates from patients with bronchiectasis (BE). Sputa were collected from BE patients who had at least one PA positive culture in the previous year. We processed the sputa to isolate both mucoid and non-mucoid PA, and determined their susceptibility pattern, mucA gene status, and presence of ciprofloxacin mutations in QRDR genes. The Biofilm production index (BPI) was obtained at 5 and 24 hours. Biofilms were imaged using Gram staining. We collected 69 PA isolates, including 33 mucoid and 36 non-mucoid. A BPI value below 14.75 at 5 hours predicted the mucoid PA phenotype with 64% sensitivity and 72% specificity. Overall, our findings suggest that the fitness-cost associated with the mucoid phenotype or ciprofloxacin resistance is shown through a time-dependent BPI profile. The BRT has the potential to reveal biofilm features with clinical implications.

Development of a combination antibiogram for empirical treatments of Pseudomonas aeruginosa at a university-affiliated teaching hospital.

The significantly higher mortality rate in the critical illness patients with Pseudomonas aeruginosa (PA) infection is linked to inappropriate selecting of empirical treatment. Traditional local antibiogram provides clinicians the resistant rate of a single antimicrobial agent to the pathogen in the specific setting. The information is valuable to the clinicians in selecting suitable empirical antibiotic therapy. However, traditional local antibiogram can only provide information for single agent empirical antibiotic not combination regimens. The combination antibiogram should be developed to facilitate the selection of appropriate antibiotics to broader the coverage rate of resistant PA. The susceptibility to the β-lactam antibiotics (piperacillin/tazobactam (PTZ), ceftazidime, cefepime, imipenem, or meropenem) or to those administered in combination with an aminoglycoside (gentamicin or amikacin) or fluoroquinolone (ciprofloxacin or levofloxacin) was calculated. The chi-square test was used to compare the differences of combination coverage rates between non-ICU and ICU isolates. 880 PA isolates were isolated during study period. The susceptibility of single agents ranged from 83.1% to 89.7%. The combination regimens containing amikacin provide the highest cover rate (98.9%-99.1%) and those containing levofloxacin provide less coverage rate (92.3%-93.9%). The susceptibility to five β-lactam single agents in ICU isolates significantly lower than non-ICU isolates. The non-ICU isolates exhibited significantly higher susceptibility to the PTZ-gentamicin (p = 0.002) and ceftazidime-gentamicin (p = 0.025) than ICU isolates. Our results support the use of aminoglycosides instead of fluoroquinolones as additive agents in empirical combination treatments for patients with critical infections caused by PA.

Evaluation of sputum cultures in children with spinal Muscular atrophy

BackgroundSpinal Muscular Atrophy (SMA) is a severe neuromuscular disorder. Despite increased survival due to novel therapies, morbidity from respiratory complications still persists. We aim to describe these patients' sputum cultures as an expression of chronic infectious airway disease. MethodsRetrospective review of medical records of all children with SMA followed at the multidisciplinary respiratory neuromuscular clinic at Schneider Childrens' Medical Center of Israel over a 16-year period. Sputum cultures were obtained during routine visits or pulmonary exacerbations. ResultsSixty-one SMA patients, aged 1 month to 21 years, were included in this cohort. Of these, sputum cultures were collected from 41 patients. Overall, 288 sputum cultures were obtained, and 98 (34%) were negative for bacterial growth. For the first culture taken from each patient, 12 out of 41 (29%) were sterile. The most common bacteria were pseudomonas aeruginosa (PSA) (38%) and staphylococcus aureus (19.6%). PSA was found in SMA type I patients more frequently than in type II patients (15/26 = 58% vs 4/13 = 31%, p < 0.001). PSA infection was positively associated with noninvasive ventilation, recurrent atelectasis, recurrent pneumonias, swallowing difficulties, but no significant association was found with cough assist machine usage. The incidence of positive cultures did not differ between those treated with Onasemnogene abeparvovec or Nusinersen compared to those without treatment, but the age of first PSA isolation was slightly older with Nusinersen treatment (p = 0.01). ConclusionsAirway bacterial colonization is common in SMA type I patients and is not decreased by Onasemnogene abeparvovec or Nusinersen treatment.

The Effect of Decreased Antipseudomonal Drug Consumption on Pseudomonas aeruginosa Incidence and Antimicrobial Susceptibility Profiles over 9 Years in a Lebanese Tertiary Care Center

Pseudomonas aeruginosa (PAE) is intrinsically resistant to numerous classes of antimicrobials such as tetracycline and β-lactam antibiotics. More epidemiological surveillance studies on the antimicrobial susceptibility profiles of PAE are needed to generate clinically significant data and better guided therapeutic options. We describe and analyze in a retrospective study the epidemiologic trends of 1827 Pseudomonas spp. isolates (83.5% PAE, 16.4% Pseudomonas sp., and 0.2% Pseudomonas putida) from various clinical specimens with their resistance patterns to antimicrobial consumption at a tertiary medical center in Lebanon between January 2010 and December 2018. We report a significant drop in the incidence of PAE from sputum (p-value = 0.05), whereas bloodstream infection isolation density showed no trend over the study period. We also registered a minimal but statistically significant drop in resistance of Pseudomonas to certain antibiotics and a decrease in the consumption of antipseudomonal antibiotics (p-value < 0.001). Only 61 PAE isolates from a total of 1827 Pseudomonas cultures (3.33%) were difficult to treat, of which only one was a bacteremia. Interestingly, we found that the carbapenem susceptibility of Pseudomonas was unaffected by the decrease in their consumption. These results augur that antimicrobial pressure may not be the sole contributor to resistance emergence. Finally, antimicrobial stewardship seems to have a positive impact on nosocomial epidemiology.

2052. Temporal and Geographical Prevalence of Carbapenem-Resistant Pseudomonas aeruginosa and the In Vitro Activity of Ceftolozane/Tazobactam and Comparators in Taiwan – SMART 2012-2020

Abstract Background Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is listed as a critical pathogen by World Health Organization (WHO). Using clinical isolates collected in Taiwan as part of the global SMART surveillance program, we evaluated the trend of CRPA prevalence in recent nine years (2012-2020) as well as in vitro activity of ceftolozane/tazobactam (C/T) and comparators against CRPA collected from ICU vs non-ICU wards from 2016 to 2020. Methods Between 2012-2020, Pseudomonas aeruginosa (PA) isolates were collected from nine sites in Taiwan (2 in Northern, 3 in Central and 4 in Southern Taiwan). MICs were determined and interpreted based on CLSI broth microdilution guidelines and 2021 CLSI breakpoints. PCR screening and β-lactamase gene sequencing were performed for isolates non-susceptible to imipenem or imipenem/relebactam or C/T. Results During the study period, a total of 2639 PA isolates were collected. Among these, 448 isolates were resistant to either imipenem or meropenem (17.0%). Yearly prevalence rate of CRPA increased from 12.3% in 2012 to 22.8% in 2020: 12.3% in 2012 (14/114), 11.5% in 2013 (16/139), 11.5% in 2014 (13/113), 12.2% in 2015 (41/336), 15.5% in 2016 (57/367), 15.9% in 2017 (68/428), 20.4% in 2018 (73/357), 19.4% in 2019 (75/386) and 22.8% (91/399) in 2020. Hospitals in Northern Taiwan had higher CRPA prevalence rate (22.8%, 131/574) compared to those in Central (15.7%, 126/802) and Southern Taiwan (15.1%, 191/1263). Percentage susceptibility of CRPA isolates to C/T from 2016 to 2020 showed 89.47% (51/57) in 2016, 79.41% (54/68) in 2017, 93.2% (68/73) in 2018, 90.7% (68/75) in 2019 and 98.9% (90/91) in 2020. For ICU vs. Non-ICU CRPA isolates, the susceptibility to C/T were 88.3% vs.93.8%, 77.8% vs. 82.5%, 92.3 % vs. 92.9%, 87.1% vs.93.2% and 100% vs. 98.26%, in 2016,2017, 2018, 2019 and 2020, respectively. Conclusion During the period of 2012-2020, the yearly prevalence of CRPA in Taiwan hospitals increased from 12.3% to 22.8%. The high prevalence and increasing trend of CRPA warrant continuous monitoring of evolving antibiotic resistance in Taiwan. Disclosures Tai-Chin Hsieh, MBBS, MSD Taiwan: Advisor/Consultant|MSD Taiwan: Employee of MSD Taiwan|MSD Taiwan: Stocks/Bonds.

Artemisinin derivative DHA27 enhances the antibacterial effect of aminoglycosides against Pseudomonas aeruginosa by inhibiting mRNA expression of aminoglycoside-modifying enzymes.

Bacterial resistance is becoming increasingly serious, the present study aimed to investigate the mechanism of antibacterial sensitization effect of DHA27 combined with tobramycin in tobramycin-resistant Pseudomonas aeruginosa (PA). We found that DHA27 combined with aminoglycosides had an antibacterial sensitization effect on PA. Tobramycin, owing to its lower toxic and side effects, was selected to further study the molecular mechanism of drug combination. A sublethal-dose bacterial challenge/sepsis mouse model was established to study the protective effect of DHA27 plus tobramycin. Scanning electron microscopy was used to investigate whether DHA27 exerts the antibacterial sensitization effect by directly affecting bacterial morphology. The effect of DHA27 on daunorubicin accumulation in bacteria was studied, and quantitative reverse transcription PCR was used to study the effect of DHA27 plus tobramycin on 16S rRNA methyltransferase and aminoglycoside-modifying enzyme mRNA expression. Twenty clinical isolates of PA were found to be tobramycin resistant; DHA27 plus tobramycin had a significant antibacterial sensitization effect on many of these resistant strains. DHA27 plus tobramycin reduced the bacterial load in the spleen and lungs of sepsis model mice and levels of proinflammatory cytokines interleukin-1β (IL-1β) and interferon-γ (IFN-γ). DHA27 plus tobramycin significantly inhibited the mRNA expression of aminoglycoside-modifying enzymes in bacteria. DHA27 combined with AGs had an antibacterial sensitization effect on PA; the molecular mechanism underlying this effect is closely related to the inhibition of the mRNA expression of aminoglycoside-modifying enzymes, especially aac(3)-II.