Resistance, mechanism, and fitness cost of specific bacteriophages for Pseudomonas aeruginosa.

The bacteriophage is an effective adjunct to existing antibiotic therapy; however, in the course of bacteriophage therapy, host bacteria will develop resistance to bacteriophages, thus affecting the efficacy. Therefore, it is important to describe how bacteria evade bacteriophage attack and the consequences of the biological changes that accompany the development of bacteriophage resistance before the bacteriophage is applied. The specific bacteriophage vB3530 of Pseudomonas aeruginosa (P. aeruginosa) has stable biological characteristics, short incubation period, strong in vitro cleavage ability, and absence of virulence or resistance genes. Ten bacteriophage-resistant strains (TL3780-R) were induced using the secondary infection approach, and the plaque assay showed that vB3530 was less sensitive to TL3780-R. Identification of bacteriophage adsorption receptors showed that the bacterial surface polysaccharide was probably the adsorption receptor of vB3530. In contrast to the TL3780 parental strain, TL3780-R is characterized by the absence of long lipopolysaccharide chains, which may be caused by base insertion of wzy or deletion of galU. It is also intriguing to observe that, in comparison to the parent strain, the bacteriophage-resistant strains TL3780-R mostly exhibited a large cost of fitness (growth rate, biofilm formation, motility, and ability to produce enhanced pyocyanin). In addition, TL3780-R9 showed increased susceptibility to aminoglycosides and chlorhexidine, which may be connected to the loss and down-regulation of mexX expression. Consequently, these findings fully depicted the resistance mechanism of P. aeruginosa to vB3530 and the fitness cost of bacteriophage resistance, laying a foundation for further application of bacteriophage therapy.IMPORTANCEThe bacteriophage is an effective adjunct to existing antibiotic therapy; However, bacteria also develop defensive mechanisms against bacteriophage attack. Thus, there is an urgent need to deeply understand the resistance mechanism of bacteria to bacteriophages and the fitness cost of bacteriophage resistance so as to lay the foundation for subsequent application of the phage. In this study, a specific bacteriophage vB3530 of P. aeruginosa had stable biological characteristics, short incubation period, strong in vitro cleavage ability, and absence of virulence or resistance genes. In addition, we found that P. aeruginosa may lead to phage resistance due to the deletion of galU and the base insertion of wzy, involved in the synthesis of lipopolysaccharides. Simultaneously, we showed the association with the biological state of the bacteria after bacteria acquire bacteriophage resistance, which is extremely relevant to guide the future application of therapeutic bacteriophages.

Assessment of the Glycan-Binding Profile of Pseudomonas aeruginosa PAO1.

Pseudomonas aeruginosa is an opportunistic pathogen that can establish acute and chronic infections in individuals who lack fully functional innate immunity. In particular, phagocytosis by neutrophils and macrophages is a key mechanism that modulates host control and clearance of P. aeruginosa. Individuals with neutropenia or cystic fibrosis are highly susceptible to P. aeruginosa infection, thus underscoring the importance of the host innate immune response. Cell-to-cell contact between host innate immune cells and the pathogen, a first step in phagocytic uptake, is facilitated by simple and complex glycan structures present at the host cell surface. We have previously shown that endogenous polyanionic N-linked glycans localized to the cell surface of phagocytes mediate the binding and subsequent phagocytosis of P. aeruginosa cells. However, the suite of glycans that P. aeruginosa cells bind to on host phagocytic cells remains poorly characterized. Here, we demonstrate, with the use of exogenous N-linked glycans and a glycan array, that P. aeruginosa PAO1 cells preferentially attach to a subset of glycans, including a bias toward monosaccharide versus more complex glycan structures. Consistent with these findings, we were able to competitively inhibit bacterial adherence and uptake by the addition of exogenous N-linked mono- and disaccharide glycans. We discuss our findings in the context of previous reports of P. aeruginosa glycan binding. IMPORTANCE P. aeruginosa cells bind to a variety of glycans as part of their interaction with host cells, and a number of P. aeruginosa-encoded receptors and target ligands have been described that allow this microbe to bind to such glycans. Here, we extend this work by studying the glycans used by P. aeruginosa PAO1 cells to bind to phagocytic cells and by using a glycan array to characterize the suite of such molecules that can facilitate host cell binding by this microbe. This study provides an increased understanding of the glycans bound by P. aeruginosa and furthermore provides a useful data set for future studies of P. aeruginosa-glycan interactions.

Histological assessment, anti-quorum sensing, and anti-biofilm activities of Dioon spinulosum extract: in vitro and in vivo approach.

Pseudomonas aeruginosa is an opportunistic bacterium causing several health problems and having many virulence factors like biofilm formation on different surfaces. There is a significant need to develop new antimicrobials due to the spreading resistance to the commonly used antibiotics, partly attributed to biofilm formation. Consequently, this study aimed to investigate the anti-biofilm and anti-quorum sensing activities of Dioon spinulosum, Dyer Ex Eichler extract (DSE), against Pseudomonas aeruginosa clinical isolates. DSE exhibited a reduction in the biofilm formation by P. aeruginosa isolates both in vitro and in vivo rat models. It also resulted in a decrease in cell surface hydrophobicity and exopolysaccharide quantity of P. aeruginosa isolates. Both bright field and scanning electron microscopes provided evidence for the inhibiting ability of DSE on biofilm formation. Moreover, it reduced violacein production by Chromobacterium violaceum (ATCC 12,472). It decreased the relative expression of 4 quorum sensing genes (lasI, lasR, rhlI, rhlR) and the biofilm gene (ndvB) using qRT-PCR. Furthermore, DSE presented a cytotoxic activity with IC50 of 4.36 ± 0.52 µg/ml against human skin fibroblast cell lines. For the first time, this study reports that DSE is a promising resource of anti-biofilm and anti-quorum sensing agents.

Subpalpebral Antibiotic Lavage as Safe, Emergent, and Cost-Effective Management of Acute Infectious Keratitis Related to Contact Lens Overwear: Case Report and Literature Review.

PURPOSE: The aim of this study is to describe the technique of subpalpebral antibiotic lavage (SAL), which is a highly therapeutic, efficient, and cost-effective method for managing severe bacterial keratitis. METHODS: This case report describes a 26-year-old woman with severe bacterial keratitis in the right eye due to contact lens overwear, with progressive corneal thinning, a hypopyon, impending perforation, and marked visual loss to perception of light despite treatment with intensive topical antibiotics. This was managed with SAL that involves the insertion of a cannula transcutaneously into the upper conjunctival fornix to provide continuous antibiotic irrigation of the ocular surface. RESULTS: By 11 weeks after presentation, the cornea and anterior chamber appeared clinically quiescent, and visual acuity improved to 20/40 corrected in the right eye. CONCLUSIONS: Bacterial keratitis is a potentially blinding condition for which contact lens wear is an important risk factor. Most cases are successfully managed with topical medications; however, in cases of treatment failure, a second-line approach such as SAL can be sight-saving. SAL uses readily available equipment for the delivery of high concentrations of antibiotics to the ocular surface, thus increasing therapeutic efficacy and reducing nursing staff workload. Despite its advantages, the literature reveals apparent underutilization of this technique.

Evaluation of Ceftazidime/Avibactam Administration in Enterobacteriaceae and Pseudomonas aeruginosa Bloodstream Infections by Monte Carlo Simulation.

PURPOSE: To evaluate the administration regimen of ceftazidime/avibactam (CZA) for bloodstream infections caused by Enterobacteriaceae and Pseudomonas aeruginosa. METHODS: The minimal inhibitory concentrations (MICs) of CZA against Enterobacteriaceae and P. aeruginosa isolated from blood cultures at member hospitals in BRICS (Blood Bacterial Resistant Investigation Collaborative System) in 2019 were determined by broth micro-dilution methodology. A 10,000-patient Monte Carlo simulation (MCS) was used to calculate the probability of target attainment (PTA) and cumulative fraction of response (CFR) for different CZA dosage regimens to evaluate their efficacies and optimize the best initial dosage regimen. RESULTS: Altogether, 6487 Enterobacteriaceae and P. aeruginosa strains were isolated from the blood cultures. The overall CZA resistance rate was 2.31%, of which the Enterobacteriaceae and P. aeruginosa rates were 1.57% and 14.29%, respectively. The MCS showed that the greater the MIC value, the worse the therapeutic effect. When the CZA MIC was ≤8 mg/L, the standard dose (2.5g iv q8h) achieved 90% PTA in the subset of patients with creatinine clearance (CrCl) values from 51 to 120 mL/min. Although the high-dose regimen (3.75g iv q8h) achieved 90% PTA in patients with CrCl values from 121 to 190 mL/min, implementing the low-dose regimen (1.25g iv q8h) was also effective for patients in the 51-89 mL/min CrCl range. Generally, the high-dose regimen (3.75g iv q8h) reached 90% CFR against all of the strains. Conversely, in patients with CrCl values of 121-190 mL/min, the standard dose (2.5g iv q8h) failed to reach 90% CFR against some Enterobacteriaceae members and P. aeruginosa. When the dose was reduced to the low-dose regimen (1.25g iv q8h), no patients reached 90% CFR against some Enterobacteriaceae members and P. aeruginosa. CONCLUSION: CZA has good antibacterial activity against Enterobacteriaceae and P. aeruginosa in bloodstream infections. Clinicians could make individualized treatment regimens in accordance with the sensitivity of the strains and the level of renal function in their patients to best predict the drug-related clinical responses.

Tools for the Real-Time Assessment of a Pseudomonas aeruginosa Infection Model.

Pseudomonas aeruginosa (Pa) is one of the most common opportunistic pathogens associated with cystic fibrosis (CF). Once Pa colonization is established, a large proportion of the infecting bacteria form biofilms within airway sputum. Pa biofilms isolated from CF sputum have been shown to grow in small, dense aggregates of ~10-1,000 cells that are spatially organized and exhibit clinically relevant phenotypes such as antimicrobial tolerance. One of the biggest challenges to studying how Pa aggregates respond to the changing sputum environment is the lack of nutritionally relevant and robust systems that promote aggregate formation. Using a synthetic CF sputum medium (SCFM2), the life history of Pa aggregates can be observed using confocal laser scanning microscopy (CLSM) and image analysis at the resolution of a single cell. This in vitro system allows the observation of thousands of aggregates of varying size in real time, three dimensions, and at the micron scale. At the individual and population levels, having the ability to group aggregates by phenotype and position facilitates the observation of aggregates at different developmental stages and their response to changes in the microenvironment, such as antibiotic treatment, to be differentiated with precision.

Assessment of Silver Levels in a Closed-Incision Negative Pressure Therapy Dressing: In Vitro and In Vivo Study.

Objective: In recent years, reticulated open-cell foam-based closed-incision negative pressure therapy (ROCF-ciNPT) has shown effectiveness in management of various postoperative incisions. These dressings consist of a skin interface layer that absorbs fluid from the skin surface and reduces the potential for microbial colonization within the dressing by means of ionic silver. This study examines the ability of silver to reduce the bioburden within the dressing as well as the localized effect due to potential silver mobility. Approach: Ability of silver to reduce bioburden within the ROCF-ciNPT dressing was assessed using Staphylococcus aureus, Pseudomonas aeruginosa, and Candida spp. Furthermore, silver mobility was assessed using an in vitro skin model to study the zone of inhibition along with released silver quantification. Using a porcine model, diffusion of silver into blood and tissue was studied using emission spectrometry and histology. Results: Microbial growth in the ROCF-ciNPT dressing was significantly reduced (∼2.7-4.9 log reduction) compared to a silver-free negative control. No zone of inhibition was observed for microbial colonies for up to 7 days with minimal localized silver release (<5.5 ppm release). In vivo studies demonstrated no measurable concentration (<0.2 µg/g) of silver in the blood, urine, feces, kidney, and liver tissue biopsy. Innovation: This study provides an important insight into silver concentration and mobility within the ROCF-ciNPT dressing, given emerging concerns associated with potential silver cytotoxicity. Conclusion: These results indicate the concentration of silver (0.019% silver by weight) in the ROCF-ciNPT dressings has been adequate to reduce bioburden within the skin interface layer, while severely limiting the amount of silver leaching out.

EDTA-modified carbapenem inactivation method (eCIM) for detecting IMP Metallo-ß-lactamase-producing Pseudomonas aeruginosa: an assessment of increasing EDTA concentrations.

BACKGROUND: Prompt identification of carbapenemase-harboring organisms is valuable in informing therapeutic and infection-control measures. The modified carbapenem inactivation method (mCIM) and EDTA-modified carbapenem inactivation method (eCIM) are inexpensive and easy to interpret phenotypic tests endorsed by the Clinical and Laboratory Standards Institute (CLSI) for the detection of carbapenemase-harboring Enterobacterales. Only mCIM is endorsed by CLSI for detecting carbapenemase-harboring Pseudomonas aeruginosa. eCIM's ability to delineate serine and metallo-ß-lactamases (MBL) could be advantageous in areas prevalent with carbapenemase-harboring P. aeruginosa. A recent assessment of mCIM/eCIM on MBL-harboring P. aeruginosa demonstrated high eCIM sensitivity for NDMs and VIMs but not for IMP-producers. Therefore, this study aimed to determine whether increasing EDTA concentrations would enhance eCIM sensitivity for a collection of IMP-harboring P. aeruginosa isolates. Twenty-six IMP-harboring P. aeruginosa isolates were utilized. For test validation, additional P. aeruginosa isolates harboring NDM (n = 3), VIM (n = 3), KPC (n = 8), wild-type (n = 1), and Enterobacterales isolates harboring IMP (n = 6) and NDM (n = 1) were assessed. The mCIM test was conducted as outlined by CLSI. Simultaneously, the eCIM test was performed with the standard 5 mM EDTA concentration and doubling EDTA concentrations: 10 mM, 20 mM, and 40 mM. RESULTS: Concentration-dependent improvement was observed among the IMP-harboring P. aeruginosa with eCIM sensitivities at 0, 31, 85, and 100% respectively. Remaining Enterobacterales and P. aeruginosa responded concordantly with their genotype at the standard 5 mM eCIM concentration, with doubling EDTA concentrations providing no greater sensitivity. CONCLUSION: Combination of mCIM and an eCIM with a 40 mM EDTA concentration appropriately capture IMP-harboring P. aeruginosa without sacrificing test utility for other carbapenemase-harboring isolates.

Econometric ARIMA methodology to elucidate the evolution of trends in nosocomial antimicrobial resistance rates in the European Union.

BACKGROUND: Infections with bacteria harbouring resistance to cephalosporins or fluoroquinolones (FQ) constitute a serious hazard to human health. OBJECTIVES: To establish a methodology based on econometric analysis and the largest European Union (EU) resistance database (EARS-Net), to model nosocomial antimicrobial resistance (AMR) in the EU and to detect tendency changes, steps or peaks. The contribution of legislation based on third-generation cephalosporin (3GC) and FQ class referrals to resistance rate patterns is evaluated. METHODS: Resistance to 3GC and FQ was examined in nosocomial Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa in at least 25 out of 30 EU countries (> 94% population coverage), weighted by their mean annual population, between 2006 and 2016. Autoregressive integrated moving average (ARIMA) model analysis, inspired by Box-Jenkins methodology, was prepared to adjust series to a mathematical model to detect hypothetical changes in the general behaviour. To the best of the authors' knowledge, this is the first study to use ARIMA with interventions to model overall nosocomial AMR data compiled in EARS-Net. RESULTS AND CONCLUSIONS: Econometric ARIMA models statistically prove the occurence of slowdowns and reversions in the increasing trend of AMR prevalence in nosocomial E. coli and K. pneumoniae to 3GC and FQ, as well as resistance of P. aeruginosa to 3GC. The resistance of P. aeruginosa to FQ exhibited a descending slope. The presented decreasing trends constitute noteworthy milestones in tackling AMR in Europe.

Dosage Regimens for Meropenem in Children with Pseudomonas Infections Do Not Meet Serum Concentration Targets.

There have been literature reports that some recommended meropenem dosage regimens may fail to meet therapeutic targets in some high-risk children and adults. We evaluated this observation in children using literature studies conducted in infants and children. Observed and, as necessary, simulated data from the literature were combined, yielding a data set of 288 subjects (1 day to ~ 17 years). A population pharmacokinetic model was fit to the data and then used to simulate the recommended dosing regimens and estimate the proportion of subjects achieving recommended target exposures. A two-compartment model best fit the data with weight, postnatal age, gestational age, and serum creatinine as covariates. The US Food and Drug Administration (FDA)-approved dosing regimens achieved targets in ~ 90% or more of subjects less than 3 months of age for organisms with minimum inhibitory concentration (MIC)'s of 2 and 4 mg/L; however, only 68.4% and 41.7% of subjects older than 3 months and weighing < 50 kg achieved target exposures for organisms with MIC's of 2 and 4 mg/L, respectively [Correction added on January 23, 2020, after first online publication: "> 3 months" corrected to "less than 3 months".]. Moreover, for subjects weighing more than 50 kg, only 41.3% and 17% achieved these respective targets. Simulation studies were used to explore the impact of changing dose, dosing interval, and infusion duration on the likelihood of achieving therapeutic targets in these groups. Our findings illustrate that current dosing recommendations for children over 3 months of age fail to meet therapeutic targets in an unacceptable fraction of patients. Further investigation is needed to develop new dosing strategies in these patients.

Measuring the in-hospital costs of Pseudomonas aeruginosa pneumonia: methodology and results from a German teaching hospital.

BACKGROUND: Pseudomonas aeruginosa-related pneumonia is an ongoing healthcare challenge. Estimating its financial burden is complicated by the time-dependent nature of the disease. METHODS: Two hundred thirty-six cases of Pseudomonas aeruginosa-related pneumonia were recorded at a 2000 bed German teaching hospital between 2011 and 2014. Thirty-five cases (15%) were multidrug-resistant (MDR) Pseudomonas aeruginosa. Hospital- and community-acquired cases were distinguished by main diagnoses and exposure time. The impact of Pseudomonas aeruginosa-related pneumonia on the three endpoints cost, reimbursement, and length of stay was analyzed, taking into account (1) the time-dependent nature of exposure, (2) clustering of costs within diagnostic groups, and (3) additional confounders. RESULTS: Pseudomonas aeruginosa pneumonia is associated with substantial additional costs that are not fully reimbursed. Costs are highest for hospital-acquired cases (€19,000 increase over uninfected controls). However, community-acquired cases are also associated with a substantial burden (€8400 when Pseudomonas aeruginosa pneumonia is the main reason for hospitalization, and €6700 when not). Sensitivity analyses for hospital-acquired cases showed that ignoring or incorrectly adjusting for time-dependency substantially biases results. Furthermore, multidrug-resistance was rare and only showed a measurable impact on the cost of community-acquired cases. CONCLUSIONS: Pseudomonas aeruginosa pneumonia creates a substantial financial burden for hospitals. This is particularly the case for nosocomial infections. Infection control interventions could yield significant cost reductions. However, to evaluate the potential effectiveness of different interventions, the time-dependent aspects of incremental costs must be considered to avoid introduction of bias.

Rapid and highly sensitive detection of pyocyanin biomarker in different Pseudomonas aeruginosa infections using gold nanoparticles modified sensor.

Successful antibiotic treatment of infections relies on accurate and rapid identification of the infectious agents. Pseudomonas aeruginosa is implicated in a wide range of human infections that mostly become complicated and life threating, especially in immunocompromised and critically ill patients. Conventional microbiological methods take more than three days to obtain accurate results. Pyocyanin is a distinctive electroactive biomarker for Pseudomonas aeruginosa. Here, we have prepared polyaniline/gold nanoparticles decorated ITO electrode and tested it to establish a rapid, diagnostic and highly sensitive pyocyanin sensor in a culture of Pseudomonas aeruginosa clinical isolates with high selectivity for traces of pyocyanin when measured in the existence of different interferences like vitamin C, uric acid, and glucose. The scanning electron microscopy and cyclic voltammetry techniques were used to characterize the morphology and electrical conductivity of the constructed electrode. The determined linear range for pyocyanin detection was from 238 µM to 1.9 µM with a detection limit of 500 nM. Compared to the screen-printed electrode used before, the constructed electrode showed a 4-fold enhanced performance. Furthermore, PANI/Au NPs/ITO modified electrodes have demonstrated the ability to detect pyocyanin directly in Pseudomonas aeruginosa culture without any potential interference with other species.

Incremental clinical and economic burden of suspected respiratory infections due to multi-drug-resistant Pseudomonas aeruginosa in the United States.

BACKGROUND: Multi-drug resistant (MDR) Pseudomonas aeruginosa can negatively affect patients and hospitals. AIM: To evaluate excess mortality and cost burden among patients hospitalized with suspected respiratory infections due to MDR P. aeruginosa vs patients with non-MDR P. aeruginosa in 78 United States (US) hospitals. METHODS: This study analyzed electronically captured microbiological and outcomes data of patients hospitalized with non-duplicate P. aeruginosa isolates from respiratory sources collected ≥3 days after admission to identify hospital-onset MDR or non-MDR P. aeruginosa per the Centers for Disease Control and Prevention definition. The risk of multi-drug resistance was estimated on mortality, length of stay (LOS), cost, operation gain/loss, and 30-day readmission. A sensitivity analysis was conducted utilizing a cohort with pharmacy data available. FINDINGS: Of 523 MDR and 1381 non-MDR P. aeruginosa cases, unadjusted mortality was 23.7% vs 18.0% and multi-variable-adjusted mortality was 20.0% (95% confidence interval (CI): 14.3-27.2%) vs 15.5% (95% CI: 11.2-20.9%; P=0.026), the average adjusted excess LOS was 6.7 days (P<0.001); excess cost per case was US$22,370 higher (P=0.002) and operational loss per case was US$10,661 (P=0.024) greater, and the multi-variable adjusted readmission rate was 16.2% (95% CI: 11.2-22.9%) vs 11.1% (95% CI: 7.8-15.6%; P=0.006). The sensitivity analysis yielded similar results. CONCLUSIONS: Compared with suspected infections due to non-MDR P. aeruginosa, patients with MDR P. aeruginosa had higher risk of mortality, readmission, and longer LOS, as well as US$20,000 incremental cost and >US$10,000 incremental net loss per case after controlling for patient and hospital characteristics.

Assessment of the In Vitro Activities of Ceftolozane/Tazobactam and Ceftazidime/Avibactam in a Collection of Beta-Lactam-Resistant Enterobacteriaceae and Pseudomonas aeruginosa Clinical Isolates at Montpellier University Hospital, France.

Objective: To assess in vitro ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA) activity in beta-lactam-resistant Enterobacteriaceae and Pseudomonas aeruginosa clinical isolates from major carbapenem-using Departments at Montpellier University Hospital, France. Materials and Methods: We tested third-generation cephalosporin-resistant Enterobacteriaceae (by production of extended spectrum ß-lactamase or other mechanisms, mainly AmpC beta-lactamases) and ceftazidime- and/or carbapenem-resistant P. aeruginosa strains isolated from clinical samples of patients hospitalized from January 2017 to May 2017 and August 2016 to July 2017, respectively. We also included all OXA-48 beta-lactamase-producing Enterobacteriaceae strains isolated in the whole hospital from October 2015 to May 2017. We used the 2017 European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines for minimal inhibitory concentration interpretation. Results: Among the 62 cephalosporin-resistant Enterobacteriaceae strains, 60 (97%) were susceptible to CZA and 34 (65%) to C/T. The two CZA-resistant Klebsiella pneumoniae isolates produced (i) NDM-carbapenemase and extended-spectrum beta-lactamase (ESBL) and (ii) ESBL CTXM-15 and OXA-1 associated with impermeability. Moreover, 31 of the 42 P. aeruginosa strains (74%) were susceptible to CZA and 37 (88%) to C/T. Finally, 26/27 (96%) of OXA-48 beta-lactamase-producing Enterobacteriaceae were susceptible to CZA and 8/27 (30%) to C/T. Conclusions: At our hospital, CZA and C/T offer a carbapenem-sparing alternative for resistant gram-negative pathogens and could be a salvage therapy for carbapenem-resistant pathogens.

Antibiotic Use and Outcomes After Implementation of the Drug Resistance in Pneumonia Score in ED Patients With Community-Onset Pneumonia.

BACKGROUND: To guide rational antibiotic selection in community-onset pneumonia, we previously derived and validated a novel prediction tool, the Drug-Resistance in Pneumonia (DRIP) score. In 2015, the DRIP score was integrated into an existing electronic pneumonia clinical decision support tool (ePNa). METHODS: We conducted a quasi-experimental, pre-post implementation study of ePNa with DRIP score (2015) vs ePNa with health-care-associated pneumonia (HCAP) logic (2012) in ED patients admitted with community-onset pneumonia to four US hospitals. Using generalized linear models, we used the difference-in-differences method to estimate the average treatment effect on the treated with respect to ePNa with DRIP score on broad-spectrum antibiotic use, mortality, hospital stay, and cost, adjusting for available patient-level confounders. RESULTS: We analyzed 2,169 adult admissions: 1,122 in 2012 and 1,047 in 2015. A drug-resistant pathogen was recovered in 3.2% of patients in 2012 and 2.8% in 2015; inadequate initial empirical antibiotics were prescribed in 1.1% and 0.5%, respectively (P = .12). A broad-spectrum antibiotic was administered in 40.1% of admissions in 2012 and 33.0% in 2015 (P < .001). Vancomycin days of therapy per 1,000 patient days in 2012 were 287.3 compared with 238.8 in 2015 (P < .001). In the primary analysis, the average treatment effect among patients using the DRIP score was a reduction in broad-spectrum antibiotic use (OR, 0.62; 95% CI, 0.39-0.98; P = .039). However, the average effects for ePNa with DRIP on mortality, length of stay, and cost were not statistically significant. CONCLUSIONS: Electronic calculation of the DRIP score was more effective than HCAP criteria for guiding appropriate broad-spectrum antibiotic use in community-onset pneumonia.

Risk Assessment After a Severe Hospital-Acquired Infection Associated With Carbapenemase-Producing Pseudomonas aeruginosa.

Importance: Resistance of gram-negative bacilli to carbapenems is rapidly emerging worldwide. In 2016, the World Health Organization defined the hospital-built environment as a core component of infection prevention and control programs. The hospital-built environment has recently been reported as a source for outbreaks and sporadic transmission events of carbapenemase-producing gram-negative bacilli from the environment to patients. Objective: To assess risk after the identification of an unexpected, severe, and lethal hospital-acquired infection caused by carbapenemase-producing Pseudomonas aeruginosa in a carbapenemase-low endemic setting. Design, Settings, and Participants: A case series study in which a risk assessment was performed on all 11 patients admitted to the combined cardiothoracic surgery and pulmonary diseases ward and the hospital-built environment in the Radboud University Medical Center, the Netherlands, in February 2018. Exposures: Water and aerosols containing carbapenemase-producing (Verona integron-mediated metallo-ß-lactamase [VIM]) P aeruginosa. Main Outcomes and Measures: Colonization and/or infection of patients and/or contamination of the environment after the detection of 1 patient infected with carbapenemase-producing (VIM) P aeruginosa. Results: A total of 5 men (age range, 60-84 years) and 6 women (age range, 55-74 years) were admitted to the combined cardiothoracic surgery and pulmonary diseases ward. The risk assessment was performed after carbapenemase-producing (VIM) P aeruginosa was unexpectedly detected in a man in his early 60s, who had undergone a left-sided pneumonectomy and adjuvant radiotherapy. No additional cases (colonization or infection) of carbapenemase-producing (VIM) P aeruginosa were detected. Plausible transmission of carbapenemase-producing P aeruginosa from the hospital environment to the patient via the air was confirmed by whole-genome sequencing, which proved the relation of Pseudomonas strains from the patient, the shower drains in 8 patient rooms, 1 sink, and an air sample. Conclusions and Relevance: This study suggests that rethinking the hospital-built environment, including shower drains and the sewage system, will be crucial for the prevention of severe and potential lethal hospital-acquired infections.

The impact of carbapenem-resistant Pseudomonas aeruginosa on clinical and economic outcomes in a Chinese tertiary care hospital: A propensity score-matched analysis.

BACKGROUND: This study aimed to estimate the impact of carbapenem-resistant Pseudomonas aeruginosa (CRPA) on clinical and economic outcomes in a Chinese tertiary care hospital. METHODS: Patients were assigned to a carbapenem-susceptible P aeruginosa group or to a CRPA group and matched using propensity score matching. In-hospital mortality, length of stay (LOS), LOS after culture, total hospital costs, daily hospital cost, and 30-day readmission were comparatively analyzed. Subgroup analysis was performed to determine the associations between the subgrouping factors and in-hospital mortality in patients with CRPA isolates. RESULTS: Within the propensity-matched cohort, in-hospital mortality (12.6% vs 7.8%; P   =   .044), LOS (median 29.0 vs 25.5 days; P   =   .026), LOS after culture (median 18.5 vs 14.0 days; P   =   .029), total hospital costs (median $6,082.0 vs $4,954.2; P  =  .015), and daily hospital cost (median $236.1 vs $223.6; P  =  .045) were significantly higher in CRPA patients than in carbapenem-susceptible P aeruginosa patients. Subgroup analysis revealed a significant interaction between CRPA and age (P  =  .009). CONCLUSION: Prevention and control of CRPA among hospitalized patients, especially among those over the age of 65 years, is a good measurement for the reduction of mortality and medical costs derived from CRPA infection or colonization.

Improvement of gram-negative susceptibility to fluoroquinolones after implementation of a pre-authorization policy for fluoroquinolone use: A decade-long experience.

OBJECTIVE: Due to concerns over increasing fluoroquinolone (FQ) resistance among gram-negative organisms, our stewardship program implemented a preauthorization use policy. The goal of this study was to assess the relationship between hospital FQ use and antibiotic resistance. DESIGN: Retrospective cohort. SETTING: Large academic medical center. METHODS: We performed a retrospective analysis of FQ susceptibility of hospital isolates for 5 common gram-negative bacteria: Acinetobacter spp., Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Primary endpoint was the change of FQ susceptibility. A Poisson regression model was used to calculate the rate of change between the preintervention period (1998-2005) and the postimplementation period (2006-2016). RESULTS: Large rates of decline of FQ susceptibility began in 1998, particularly among P. aeruginosa, Acinetobacter spp., and E. cloacae. Our FQ restriction policy improved FQ use from 173 days of therapy (DOT) per 1,000 patient days to <60 DOT per 1,000 patient days. Fluoroquinolone susceptibility increased for Acinetobacter spp. (rate ratio [RR], 1.038; 95% confidence interval [CI], 1.005-1.072), E. cloacae (RR, 1.028; 95% CI, 1.013-1.044), and P. aeruginosa (RR, 1.013; 95% CI, 1.006-1.020). No significant change in susceptibility was detected for K. pneumoniae (RR, 1.002; 95% CI, 0.996-1.008), and the susceptibility for E. coli continued to decline, although the decline was not as steep (RR, 0.981; 95% CI, 0.975-0.987). CONCLUSIONS: A stewardship-driven FQ restriction program stopped overall declining FQ susceptibility rates for all species except E. coli. For 3 species (ie, Acinetobacter spp, E. cloacae, and P. aeruginosa), susceptibility rates improved after implementation, and this improvement has been sustained over a 10-year period.

An in vitro assessment of bacterial transfer by products used in debridement.

OBJECTIVE: The aim of this in vitro study was to investigate the transfer of viable Pseudomonas aeruginosa biofilm microorganisms following treatment with debridement tools. METHOD: The level of viable biofilm microorganisms transferred by debridement tools was compared following treatment that reflected the clinical practice of each product. RESULTS: A significant level of microorganism transfer was seen in response to the mechanical debridement tool. Minimal transfer of microorganisms was seen when in vitro-established biofilms were treated with hydroresponsive wound dressing + polyhexamethylene biguanide (HRWD+PHMB, HydroClean plus). Less Pseudomonas aeruginosa was recovered from explants exposed to dressings compared with those exposed to debridement tools suggesting that there was less transfer of bacteria by dressings. CONCLUSION: The reduced transfer of viable microorganisms by HRWD+PHMB may be the result of significant binding and retention of microbes by the superabsorbent polymer within the dressing, together with enhanced sequestered bacterial killing within the dressing by polymer-bound PHMB. The high levels of microbial transfer/transmission seen for debridement tools suggests that, in the clinical setting, a significant level of bacterial spread over the wound surface and/or surrounding skin by these cleansing tools is likely.