Intensive care unit-acquired pneumonia due to Pseudomonas aeruginosa with and without multidrug resistance

Dynamic optimization elucidates higher-level pathogenicity strategies of Pseudomonas aeruginosa

Multiple dangerous pathogens from the World Health Organization's priority list possess a plethora of virulence components, including the ability to survive inside macrophages. Often, the pathogens rely on a multi-layered defence strategy in order to defend themselves against the immune system. Here, a minimal model is proposed to study such a strategy. By way of example, we consider the interaction between Pseudomonas aeruginosa and the human host, in which the host and the pathogen counter each other in a back-and-forth interaction. In particular, the pathogen attacks the host, macrophages of the host engulf the pathogen and reduce its access to glucose, the pathogen activates the glyoxylate shunt, which is started by the enzyme isocitrate lyase (Icl), the host inhibits it by itaconic acid, and the pathogen metabolizes itaconic acid using the enzyme succinyl-CoA:itaconate CoA transferase (Ict). The flux through the glyoxylate shunt allows the pathogen to avoid carbon loss and oxidative stress. These functions are of utmost importance inside a phagolysosome. Therefore, the pathogen needs to allocate its limited protein resource between the enzymes Icl and Ict in order to maximize the time integral of a flux through the enzyme Icl. We use both random search and dynamic optimization to identify the enzyme Ict as a cost-effective means of counter-counter-counter-defence and as a possible drug target during the early phase of infection.

Impact of Pseudomonas aeruginosa carriage on intensive care unit-acquired pneumonia: a European multicentre prospective cohort study

OBJECTIVES

Pseudomonas aeruginosa (PA) is a common causative pathogen of pneumonia acquired in the intensive care unit (ICU). The aim of this study was to determine the incidence of PA ICU pneumonia (PAIP) and to quantify its independent association with PA colonization at different body sites.

METHODS

Adult patients on mechanical ventilation at ICU admission were prospectively enrolled across 30 European ICUs. PA colonization in the perianal area and in the lower respiratory tract was assessed within 72 hours after ICU admission and twice weekly until ICU discharge. PAIP development was evaluated daily. Competing risk models with colonization as a time-varying exposure and ICU death and discharge as competing events were fitted and adjusted for confounders to investigate the association between PA carriage and PAIP.

RESULTS

A total of 1971 subjects were enrolled. The colonization prevalence with PA in the first 72 hours of ICU admission was 10.4% (179 perianal and 51 respiratory), whereas the acquisition incidence during the ICU stay was 7.0% (158 perianal and 47 respiratory). Of the 43 (1.8%) patients who developed PAIP, 11 (25.6%) were PA colonized on admission and 9 (20.9%) acquired colonization before PAIP onset. Both perianal (adjusted subdistribution hazard ratio, 4.4; 95% CI, 1.7-11.6) and respiratory colonization (adjusted subdistribution hazard ratio: 4.6, 95% CI, 1.9-11.1) were independently associated with PAIP development.

DISCUSSION

PAIP incidence was higher in PA colonized vs. non-colonized patients. Colonization of both the rectum and of the respiratory tract was associated with development of PAIP. The increased risk of PA colonization for subsequent infection provides an opportunity for targeted preventive interventions.

Kaempferol Mitigates Pseudomonas aeruginosa-Induced Acute Lung Inflammation Through Suppressing GSK3β/JNK/c-Jun Signaling Pathway and NF-κB Activation

Background: Pseudomonas aeruginosa, one of the common bacterial pathogens causing nosocomial pneumonia, is characterized as highly pathogenic and multidrug-resistant. Kaempferol (KP), a natural flavonoid, has been shown to exhibit effectiveness in treating infection-induced lung injury. Methods: We applied network pharmacology to explore the underlying mechanisms of KP in treating P. aeruginosa pneumonia and further validated them through a mouse model of acute bacterial lung infection and an in vitro macrophage infection model. Results: The in vivo studies demonstrated that treatment with KP suppressed the production of proinflammatory cytokines, including TNF, IL-1β, IL-6, and MIP-2, and attenuated the neutrophil infiltration and lesions in lungs, leading to an increased survival rate of mice. Further studies revealed that KP treatment enhanced the phosphorylation of GSK3β at Ser9 and diminished the phosphorylation of JNK, c-Jun, and NF-κB p65 in lungs in comparison to the mice without drug treatment. Consistently, the in vitro studies showed that pretreatment with KP reduced the activation of GSK3β, JNK, c-Jun, and NF-κB p65 and decreased the levels of the proinflammatory cytokines in macrophages during P. aeruginosa infection. Conclusions: KP reduced the production of proinflammatory cytokines by inhibiting GSK3β/JNK/c-Jun signaling pathways and NF-κB activation, which effectively mitigated the P. aeruginosa-induced acute lung inflammation and injury, and elevated the survival rates of mice.

Risk factors for detection of Pseudomonas aeruginosa in clinical samples upon hospital admission

BACKGROUND/INTRODUCTION

Antipseudomonal antibiotics are frequently used in patients admitted to hospitals. Many of these substances are classified as a reserve or watch status by the WHO. Inappropriate risk assessment of invasive detection of P. aeruginosa (PAE) can be a reason for overuse of antipseudomonal antibiotics. Therefore it is important to define relevant and specific risk factors for invasive PAE detection.

OBJECTIVE

The objective of this study was to identify risk factors for invasive detection of PAE in patients upon hospital admission.

METHODS

All patients 18 years of age and older with a detection of PAE and/or Enterobacterales in clinical samples taken within 48 h of admission to one of the hospitals of Charité Universitätsmedizin Berlin between 2015 and 2020 were included into this retrospective cohort study.

RESULTS

Overall, we included a total of 27,710 patients. In 3,764 (13.6%) patients PAE was detected in clinical samples taken within 48 h after admission. The most frequently detected Enterobacterales was E. coli in 14.142 (51%) patients followed by Klebsiella spp. in 4.432 (16%) patients. Multivariable regression analysis identified that prior colonisation with a multi drug resistant PAE or detection of a PAE in clinical samples during a previous hospitalisation increased the risk for invasive detection of PAE (OR 39.41; 95% CI 28.54-54.39) and OR 7.87 (95% CI 6.60-9.38) respectively. Admission to a specialised ward for patients with cystic fibrosis was associated with an increased risk (OR 26.99; 95% CI 20.48-35.54). Presence of chronic pulmonary disease (OR 2.05; 95% CI 1.85-2.26), hemiplegia (OR 2.16; 95% CI 1.90-2.45) and male gender (OR 1.60; 95% CI 1.46-1.75) were associated with a modest increase in risk for presence of PAE.

CONCLUSION

Patients with a prior detection of P. aeruginosa or admission to a cystic fibrosis ward had the highest risk for invasive detection of P. aeruginosa. Adherence to specific risk scores based on local risk factors could help to optimize prescription of anti-pseudomonal antibiotics that categorized as reserve and watch.

Difficult-to-Treat Pseudomonas aeruginosa Infections in Critically Ill Patients: A Comprehensive Review and Treatment Proposal

The management of infections caused by difficult-to-treat Pseudomonas aeruginosa in critically ill patients poses a significant challenge. Optimal antibiotic therapy is crucial for patient prognosis, yet the numerous resistance mechanisms of P. aeruginosa, which may even combine, complicate the selection of an appropriate antibiotic. In this review, we examine the epidemiology, resistance mechanisms, risk factors, and available and future therapeutic options, as well as strategies for treatment optimization. Finally, we propose a treatment algorithm to facilitate decision making based on the resistance patterns specific to each Intensive Care Unit.

Traditional Chinese Medicine Monomer Bakuchiol Attenuates the Pathogenicity of Pseudomonas aeruginosa via Targeting PqsR

As the antibiotic resistance of pathogens becomes increasingly severe, it is becoming more feasible to use methods that suppress the virulence of pathogens rather than exerting selective pressure on their growth. Pseudomonas aeruginosa, a dangerous opportunistic pathogen, infects hosts by producing multiple virulence factors, which are regulated by quorum-sensing (QS) systems, including the las systems, rhl systems, and pqs systems. This study used the chromosome lacZ transcription fusion reporter model to screen the traditional Chinese medicine monomer library and found that bakuchiol can effectively inhibit the pqs system and related virulence phenotypes of P. aeruginosa, including the production of virulence factors (pyocyanin, hydrogen cyanide, elastase, and lectin) and motility (swarming, swimming, and twitching motility) without affecting its growth. Subsequently, through genetic complementation analysis, we found that bakuchiol inhibited the function of the transcriptional activation protein PqsR of the pqs system in P. aeruginosa in a concentration-dependent manner. Furthermore, molecular dynamics simulation study results indicated that bakuchiol can target PqsR of the pqs system, thereby inhibiting the pqs system. Among the amino acids in PqsR, ALA-168 may be a key amino acid residue in the hydrophobic interaction between PqsR protein and bakuchiol. Finally, in vivo experiments demonstrated that bakuchiol attenuated the pathogenicity of P. aeruginosa to Chinese cabbage (Brassica pekinensis) and Caenorhabditis elegans. In summary, this study suggests that bakuchiol is an effective inhibitor that targets the pqs system of P. aeruginosa, providing a new strategy for addressing P. aeruginosa infections.

Progress in the study of mefloquine as an antibiotic adjuvant for combination bacterial inhibition treatment

Antimicrobial resistance is among the greatest threats to public health globally, and drug repurposing strategies may be advantageous to addressing this problem. Mefloquine, a drug traditionally used to treat malaria, has emerged as a promising antibiotic adjuvant, due to its ability to enhance the effectiveness of conventional antibiotics against resistant bacterial strains. In this paper, we first outline the enhancement properties of mefloquine and its mechanisms of action as an adjuvant antibiotic against multidrug-resistant bacteria. Mefloquine exhibits synergistic bacteriostatic effects when combined with colistin, β-lactams, antituberculosis drugs, quinolones, and linezolid. Potential mechanisms underlying its synergistic effects include inhibition of antibiotic efflux, disruption of bacterial cell membrane integrity, and disturbance of biofilm formation. In addition, we explore the bacteriostatic effects of several mefloquine derivatives against Mycobacterium tuberculosis and some fungi. Further, we summarize the findings of recent studies on other aspects of mefloquine activity, including its antiviral and antitumor effects. Finally, the advantages and challenges of mefloquine use as an antibiotic adjuvant in combination with antibiotics for bacterial inhibition are discussed. Overall, mefloquine shows excellent potential as an antibiotic adjuvant therapy against multidrug-resistant bacteria and is a promising candidate for combination therapy; however, further studies are needed to fully elucidate its mechanism of action and address the challenges associated with its clinical application.

Direct prediction of antimicrobial resistance in Pseudomonas aeruginosa by metagenomic next-generation sequencing

Objective

Pseudomonas aeruginosa has strong drug resistance and can tolerate a variety of antibiotics, which is a major problem in the management of antibiotic-resistant infections. Direct prediction of multi-drug resistance (MDR) resistance phenotypes of P. aeruginosa isolates and clinical samples by genotype is helpful for timely antibiotic treatment.

Methods

In the study, whole genome sequencing (WGS) data of 494 P. aeruginosa isolates were used to screen key anti-microbial resistance (AMR)-associated genes related to imipenem (IPM), meropenem (MEM), piperacillin/tazobactam (TZP), and levofloxacin (LVFX) resistance in P. aeruginosa by comparing genes with copy number differences between resistance and sensitive strains. Subsequently, for the direct prediction of the resistance of P. aeruginosa to four antibiotics by the AMR-associated features screened, we collected 74 P. aeruginosa positive sputum samples to sequence by metagenomics next-generation sequencing (mNGS), of which 1 sample with low quality was eliminated. Then, we constructed the resistance prediction model.

Results

We identified 93, 88, 80, 140 AMR-associated features for IPM, MEM, TZP, and LVFX resistance in P. aeruginosa. The relative abundance of AMR-associated genes was obtained by matching mNGS and WGS data. The top 20 features with importance degree for IPM, MEM, TZP, and LVFX resistance were used to model, respectively. Then, we used the random forest algorithm to construct resistance prediction models of P. aeruginosa, in which the areas under the curves of the IPM, MEM, TZP, and LVFX resistance prediction models were all greater than 0.8, suggesting these resistance prediction models had good performance.

Conclusion

In summary, mNGS can predict the resistance of P. aeruginosa by directly detecting AMR-associated genes, which provides a reference for rapid clinical detection of drug resistance of pathogenic bacteria.

Characterization and genomic analysis of a broad-spectrum lytic phage HZ2201 and its antibiofilm efficacy against Pseudomonas aeruginosa

Pseudomonas aeruginosa is a clinically common conditionally pathogenic bacterium, and the abuse of antibiotics has exacerbated its drug resistance in recent years. This has resulted in extensive reports about the usage of Pseudomonas aeruginosa phage as a novel antibacterial drug. In this study, we isolated a novel phage HZ2201 with a broad lytic spectrum. The lytic rate of this phage against Pseudomonas aeruginosa reached 78.38% (29/37), including 25 multi-drug- and carbapenem-resistant Pseudomonas aeruginosa strains. Transmission electron microscopy revealed that phage HZ2201 belongs to the class Caudoviricetes. Biological characterization showed that phage HZ2201 had an latent period of 40 min, a lytic period of 20 min, and a burst size of 440 PFU/cell, with improved tolerance to temperature and pH. Considering genomic analysis, the HZ2201 genome was a circular double-stranded DNA with a size of 45,431 bp and a guanine-cytosine (G + C) content of 52.16%, and contained 3 tRNAs. 27 of the 74 open reading frames (ORFs) annotated by the Rapid Annotation using Subsystem Technology (RAST) tool could be matched to the genomes of known functions, and no genes related to virulence and antibiotic resistance were found. The phylogenetic tree suggests that phage HZ2201 is highly related to the phage ZCPS1 and PaP3, and ORF57 and ORF17 are predicted to encode a holin and an endolysin, respectively. Cell lysis by HZ2201 proceeds through the holin-endolysin system, suggesting that it is a novel phage. Additionally, we demonstrated that phage HZ2201 has a high inhibitory capacity against Pseudomonas aeruginosa biofilms. The results of our study suggest that phage HZ2201 is a novel potential antimicrobial agent for treating drug-resistant Pseudomonas aeruginosa infection.

Bibliometric Analysis of Global Research Output on Antimicrobial Resistance among Pneumonia Pathogens (2013-2023)

Antimicrobial resistance (AMR) is a pressing global concern, posing significant challenges to the effective treatment of infections, including pneumonia. This bibliometric analysis aims to investigate the research output on AMR among pneumonia pathogens from 2013 to 2023. Data were extracted from the Web of Science Core Collection (WOS-CC) using an inclusive search strategy. The analysis included 152 relevant studies published in 99 different sources, involving 988 authors and yielding an average of 16.33 citations per document over the past decade. The findings reveal a notable increase in research on AMR among pneumonia pathogens, indicating a growing awareness of this critical issue. Collaborative studies were prevalent, with the majority of authors engaging in joint research efforts. Bradford's Law identified twelve core journals that were instrumental in disseminating research in this field, with "Medicine" emerging as the most prolific journal. The USA and China emerged as the leading contributors, while Germany displayed a strong inclination towards collaborative research. Intermountain Medical Center, Saitama Medical University, and Udice-French Research Universities were the most productive institutions, and Yayan J. and Rasche K. were the top authors. Furthermore, the analysis identified commonly encountered microorganisms such as Acinetobacter baumanii and Klebsiella pneumoniae in the context of AMR. Time-based analysis of keywords highlighted the significance of terms like "community-acquired pneumonia" and "ventilator-associated pneumonia". Overall, this comprehensive study sheds light on the global research landscape of AMR among pneumonia pathogens. The insights gained from this analysis are essential for guiding future research priorities and collaborative efforts to combat AMR effectively and improve treatment outcomes for pneumonia and related infections. As the frequency of reports concerning resistance among pneumonia pathogens, notably A. baumannii and K. pneumoniae, continues to rise, there is an immediate requirement for pharmaceutical manufacturers and healthcare providers to respond proactively and ready themselves for the forthcoming implications of this matter. It also underscores the importance of knowledge dissemination and evidence-based interventions to address this growing public health challenge. However, the study acknowledges the limitations associated with using a single publication database and encourages the inclusion of data from other sources in future research.

Engineered live bacteria suppress Pseudomonas aeruginosa infection in mouse lung and dissolve endotracheal-tube biofilms

Engineered live bacteria could provide a new modality for treating lung infections, a major cause of mortality worldwide. In the present study, we engineered a genome-reduced human lung bacterium, Mycoplasma pneumoniae, to treat ventilator-associated pneumonia, a disease with high hospital mortality when associated with Pseudomonas aeruginosa biofilms. After validating the biosafety of an attenuated M. pneumoniae chassis in mice, we introduced four transgenes into the chromosome by transposition to implement bactericidal and biofilm degradation activities. We show that this engineered strain has high efficacy against an acute P. aeruginosa lung infection in a mouse model. In addition, we demonstrated that the engineered strain could dissolve biofilms formed in endotracheal tubes of patients with ventilator-associated pneumonia and be combined with antibiotics targeting the peptidoglycan layer to increase efficacy against Gram-positive and Gram-negative bacteria. We expect our M. pneumoniae-engineered strain to be able to treat biofilm-associated infections in the respiratory tract.

Antimicrobial resistance of Pseudomonas aeruginosa isolated from patients with pneumonia during the COVID-19 pandemic and pre-pandemic periods in Northeast Brazil

Healthcare-related infections caused by resistant microorganisms are a severe public health problem and are becoming increasingly prevalent in the hospital environment, especially Pseudomonas aeruginosa. This work aimed to evaluate the resistance profile of Pseudomonas aeruginosa to antimicrobials before the COVID-19 pandemic and during the pandemic period. Bacteria strains were obtained from tracheal aspiration, sputum, and bronchoalveolar lavage for diagnosis and phenotypic characterization. Matrix assisted laser-desorption ionization-time of flight mass spectrometry (MALD-TOF MS) was used to identify strains. Automated Phoenix and VITEK® 2 Compact system and the disc diffusion method were performed to determine the antimicrobial susceptibility profile. A total of 41,000 medical reports from adult patients with pneumonia were analyzed. Of these, 951 patients were positive for P. aeruginosa, of which 373 were related to the pre-pandemic period and 578 to the pandemic period. Older men (≥60 years) were more prevalent in both periods. P. aeruginosa strains were resistant to imipenem in both periods: 38.8 and 42.5%, respectively, followed by meropenem (34.2 and 39.2%), ciprofloxacin (33.6 and 36.7%), and levofloxacin (34.9 and 43.5%). Intensive care units had the highest percentage of affected patients (62 and 65%) compared with other sectors, with a prevalence of 71% in the public network before COVID-19 and 59% during the pandemic. Our data showed a prevalence of P. aeruginosa in elderly patients in both the pre-pandemic and pandemic periods. In addition, an increase in P. aeruginosa resistance to beta-lactams, quinolones, carbapenems, and cephalosporins was observed during the COVID-19 pandemic compared with the period before the pandemic, especially in ICUs.

Bacteriophage-Antibiotic Combination Therapy against Pseudomonas aeruginosa

Phage therapy is an alternative therapy that is being used as the last resource against infections caused by multidrug-resistant bacteria after the failure of standard treatments. Pseudomonas aeruginosa can cause pneumonia, septicemia, urinary tract, and surgery site infections mainly in immunocompromised people, although it can cause infections in many different patient profiles. Cystic fibrosis patients are particularly vulnerable. In vitro and in vivo studies of phage therapy against P. aeruginosa include both bacteriophages alone and combined with antibiotics. However, the former is the most promising strategy utilized in clinical infections. This review summarizes the recent studies of phage-antibiotic combinations, highlighting the synergistic effects of in vitro and in vivo experiments and successful treatments in patients.

Treatment of critically ill patients with cefiderocol for infections caused by multidrug-resistant pathogens: review of the evidence

Appropriate antibiotic treatment for critically ill patients with serious Gram-negative infections in the intensive care unit is crucial to minimize morbidity and mortality. Several new antibiotics have shown in vitro activity against carbapenem-resistant Enterobacterales (CRE) and difficult-to-treat resistant Pseudomonas aeruginosa. Cefiderocol is the first approved siderophore beta-lactam antibiotic with potent activity against multidrug-resistant, carbapenem-resistant, difficult-to-treat or extensively drug-resistant Gram-negative pathogens, which have limited treatment options. The spectrum of activity of cefiderocol includes drug-resistant strains of Acinetobacter baumannii, P. aeruginosa, Stenotrophomonas maltophilia, Achromobacter spp. and Burkholderia spp. and CRE that produce serine- and/or metallo-carbapenemases. Phase 1 studies established that cefiderocol achieves adequate concentration in the epithelial lining fluid in the lung and requires dosing adjustment for renal function, including patients with augmented renal clearance and continuous renal-replacement therapy (CRRT); no clinically significant drug-drug interactions are expected. The non-inferiority of cefiderocol versus high-dose, extended-infusion meropenem in all-cause mortality (ACM) rates at day 14 was demonstrated in the randomized, double-blind APEKS-NP Phase 3 clinical study in patients with nosocomial pneumonia caused by suspected or confirmed Gram-negative bacteria. Furthermore, the efficacy of cefiderocol was investigated in the randomized, open-label, pathogen-focused, descriptive CREDIBLE-CR Phase 3 clinical study in its target patient population with serious carbapenem-resistant Gram-negative infections, including hospitalized patients with nosocomial pneumonia, bloodstream infection/sepsis, or complicated urinary tract infections. However, a numerically greater ACM rate with cefiderocol compared with BAT led to the inclusion of a warning in US and European prescribing information. Cefiderocol susceptibility results obtained with commercial tests should be carefully evaluated due to current issues regarding their accuracy and reliability. Since its approval, real-world evidence in patients with multidrug-resistant and carbapenem-resistant Gram-negative bacterial infections suggests that cefiderocol can be efficacious in certain critically ill patient groups, such as those requiring mechanical ventilation for COVID-19 pneumonia with subsequently acquired Gram-negative bacterial superinfection, and patients with CRRT and/or extracorporeal membrane oxygenation. In this article, we review the microbiological spectrum, pharmacokinetics/pharmacodynamics, efficacy and safety profiles and real-world evidence for cefiderocol, and look at future considerations for its role in the treatment of critically ill patients with challenging Gram-negative bacterial infections.

Resistance genomics and molecular epidemiology of high-risk clones of ESBL-producing Pseudomonas aeruginosa in young children

Introduction

The emergence of multidrug-resistant Pseudomonas aeruginosa poses a global threat, but the distribution and resistance profiling are unclear, especially in young children. Infections due to P. aeruginosa are common, associated with high mortality, and increasingly β-lactam drug resistant.

Methods

We studied the molecular epidemiology and antibiotic resistance mechanisms in 294 clinicalisolates of P. aeruginosa from a pediatric hospital in China. Non-duplicate isolates were recovered from clinical cases and were identified using an API-20 kit followed by antimicrobial susceptibility testing using the VITEK®2 compact system (BioMerieux, France) and also by broth dilution method. In addition, a double-disc synergy test for the ESBL/E-test for MBL was performed. The presence of beta-lactamases, plasmid types, and sequence types was determined by PCR and sequencing.

Results

Fifty-six percent (n = 164) of the isolates were resistant to piperacillin-tazobactam, followed by cefepime (40%; n = 117), ceftazidime (39%; n = 115), imipenem (36%; n = 106), meropenem (33%; n = 97), and ciprofloxacin (32%; n = 94). Forty-two percent (n = 126) of the isolates were positive for ESBL according to the double-disc synergy test. The blaCTX-M-15 cephalosporinase was observed in 32% (n = 40/126), while 26% (n = 33/126) werepositive for blaNDM-1 carbapenemase. Aminoglycoside resistance gene aac(3)IIIawas observed in 16% (n = 20/126), and glycylcyclines resistance gene tet(A) was observed in 12% (n = 15/126) of the isolates. A total of 23 sequence types were detected, including ST1963 (12%; n = 16), followed by ST381 (11%; n = 14), ST234 (10%; n = 13), ST145 (58%; n = 10), ST304 (57%; n = 9), ST663 (5%; n = 7), and a novel strain. In ESBL-producing P. aeruginosa, 12 different Incompatibility groups (Inc) were observed, the most common being IncFI, IncFIS, and IncA/C. The MOBP was the most common plasmid type, followed by MOBH, MOBF, and MOBQ.

Discussion

Our data suggest that the spread of antibiotic resistance is likely due toclonal spread and dissemination of different clinical strains of P. aeruginosa harbouring different plasmids. This is a growing threat in hospitals particularly in young children which needs robust prevention strategies.

Metabolite interactions between host and microbiota during health and disease: Which feeds the other?

Metabolites produced by the host and microbiota play a crucial role in how human bodies develop and remain healthy. Most of these metabolites are produced by microbiota and hosts in the digestive tract. Metabolites in the gut have important roles in energy metabolism, cellular communication, and host immunity, among other physiological activities. Although numerous host metabolites, such as free fatty acids, amino acids, and vitamins, are found in the intestine, metabolites generated by gut microbiota are equally vital for intestinal homeostasis. Furthermore, microbiota in the gut is the sole source of some metabolites, including short-chain fatty acids (SCFAs). Metabolites produced by microbiota, such as neurotransmitters and hormones, may modulate and significantly affect host metabolism. The gut microbiota is becoming recognized as a second endocrine system. A variety of chronic inflammatory disorders have been linked to aberrant host-microbiota interplays, but the precise mechanisms underpinning these disturbances and how they might lead to diseases remain to be fully elucidated. Microbiome-modulated metabolites are promising targets for new drug discovery due to their endocrine function in various complex disorders. In humans, metabolotherapy for the prevention or treatment of various disorders will be possible if we better understand the metabolic preferences of bacteria and the host in specific tissues and organs. Better disease treatments may be possible with the help of novel complementary therapies that target host or bacterial metabolism. The metabolites, their physiological consequences, and functional mechanisms of the host-microbiota interplays will be highlighted, summarized, and discussed in this overview.

Administration of Bacteriophages via Nebulization during Mechanical Ventilation: In Vitro Study and Lung Deposition in Macaques

Bacteriophages have been identified as a potential treatment option to treat lung infection in the context of antibiotic resistance. We performed a preclinical study to predict the efficacy of delivery of bacteriophages against Pseudomonas aeruginosa (PA) when administered via nebulization during mechanical ventilation (MV). We selected a mix of four anti-PA phages containing two Podoviridae and two Myoviridae, with a coverage of 87.8% (36/41) on an international PA reference panel. When administered via nebulization, a loss of 0.30–0.65 log of infective phage titers was measured. No difference between jet, ultrasonic and mesh nebulizers was observed in terms of loss of phage viability, but a higher output was measured with the mesh nebulizer. Interestingly, Myoviridae are significantly more sensitive to nebulization than Podoviridae since their long tail is much more prone to damage. Phage nebulization has been measured as compatible with humidified ventilation. Based on in vitro measurement, the lung deposition prediction of viable phage particles ranges from 6% to 26% of the phages loaded in the nebulizer. Further, 8% to 15% of lung deposition was measured by scintigraphy in three macaques. A phage dose of 1 × 109 PFU/mL nebulized by the mesh nebulizer during MV predicts an efficient dose in the lung against PA, comparable with the dose chosen to define the susceptibility of the strain.

Pretreatment with 3-methyladenine ameliorated Pseudomonas aeruginosa-induced acute pneumonia by inhibiting cell death of neutrophils in a mouse infection model

Pseudomonas aeruginosa is one of the leading causes of nosocomial infections worldwide. Clinical isolates that are resistant to multiple antimicrobials make it intractable. The interactions between P. aeruginosa and host cell death have multiple effects on bacterial clearance and inflammation; however, the potential intervention effects remain to be defined. Herein, we demonstrated that intravenous administration of 3-methyladenine before, but not after, P. aeruginosa infection enhanced autophagy-independent survival, which was accompanied by a decrease in the bacterial load, alleviation of pathology and reduction in inflammatory cytokines, in an acute pneumonia mouse model. Interestingly, these beneficial effects were not dependent on neutrophil recruitment or phagocytosis, but on the enhanced killing capacity induced by inhibiting the cell death of 3-MA pretreated neutrophils. These findings demonstrate a novel protective role of 3-MA pretreatment in P. aeruginosa-induced acute pneumonia.

Clinical risk factors for admission with Pseudomonas and multidrug-resistant Pseudomonas community-acquired pneumonia

Background

Microbial etiology for community-acquired pneumonia (CAP) is evolving with pathogens known for high CAP mortality e.g., Pseudomonas species. Chronic obstructive pulmonary disease (COPD) patients are at risk for hospitalization for CAP. Understanding regional patterns and risk factors for multidrug-resistant (MDR) Pseudomonas acquisition has implications for antimicrobial stewardship.

Objectives

To evaluate the regional epidemiology of MDR Pseudomonas CAP and its association with COPD.

Methods

We queried the electronic medical records of the University of Alabama at Birmingham Healthcare System to identify patients hospitalized for CAP with Pseudomonas positive respiratory samples between 01/01/2013–12/31/2019. Log binomial regression models were used to examine associations between COPD diagnosis and risk of Pseudomonas/MDR Pseudomonas CAP.

Results

Cohort consisted of 913 culture positive CAP cases aged 59-year (IQR:48–68), 61% (560) male, 60% (547) white, 65% (580) current/past smokers, and 42% (384) COPD. Prevalence of Pseudomonas CAP in culture positive CAP was 18% (167), MDR Pseudomonas CAP in Pseudomonas CAP was 22% (36), and yearly incidence of MDR Pseudomonas CAP was stable (p = 0.169). COPD was associated with Pseudomonas CAP (RR 1.39; 95% CI 1.01, 1.91; p = 0.041) but not with MDR Pseudomonas CAP (0.71; 95% CI 0.35, 1.45; p = 0.349). Stroke (RR 2.64; 95% CI 1.51, 4.61; p = 0.0006) and use of supplemental oxygen (RR 2.31; 95% CI 1.30, 4.12; p = 0.005) were associated with MDR Pseudomonas CAP.

Conclusion

Incidence of MDR Pseudomonas CAP was stable over time. COPD was associated with Pseudomonas CAP but not with MDR Pseudomonas CAP. Larger cohort studies are needed to confirm findings.

Essential Oils Biofilm Modulation Activity and Machine Learning Analysis on Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

The opportunistic pathogen Pseudomonas aeruginosa is often involved in airway infections of cystic fibrosis (CF) patients. It persists in the hostile CF lung environment, inducing chronic infections due to the production of several virulence factors. In this regard, the ability to form a biofilm plays a pivotal role in CF airway colonization by P. aeruginosa. Bacterial virulence mitigation and bacterial cell adhesion hampering and/or biofilm reduced formation could represent a major target for the development of new therapeutic treatments for infection control. Essential oils (EOs) are being considered as a potential alternative in clinical settings for the prevention, treatment, and control of infections sustained by microbial biofilms. EOs are complex mixtures of different classes of organic compounds, usually used for the treatment of upper respiratory tract infections in traditional medicine. Recently, a wide series of EOs were investigated for their ability to modulate biofilm production by different pathogens comprising S. aureus, S. epidermidis, and P. aeruginosa strains. Machine learning (ML) algorithms were applied to develop classification models in order to suggest a possible antibiofilm action for each chemical component of the studied EOs. In the present study, we assessed the biofilm growth modulation exerted by 61 commercial EOs on a selected number of P. aeruginosa strains isolated from CF patients. Furthermore, ML has been used to shed light on the EO chemical components likely responsible for the positive or negative modulation of bacterial biofilm formation.

Immunometabolic crosstalk during bacterial infection

Following detection of bacteria, macrophages switch their metabolism from oxidative respiration through the tricarboxylic acid cycle to high-rate aerobic glycolysis. This immunometabolic shift enables pro-inflammatory and antimicrobial responses and is facilitated by the accumulation of fatty acids, tricarboxylic acid-derived metabolites and catabolism of amino acids. Recent studies have shown that these immunometabolites are co-opted by pathogens as environmental cues for expression of virulence genes. We review mechanisms by which host immunometabolites regulate bacterial pathogenicity and discuss opportunities for the development of therapeutics targeting metabolic host-pathogen crosstalk.

A comparison of rectal and oral cultivable microbiota in wild and captive black lion tamarins (Leontopithecus chrysopygus, Mikan 1823)

The black lion tamarin (Leontopithecus chrysopygus) is an endangered primate species, restricted to the Atlantic Forest fragments of São Paulo state, Brazil, with an estimated wild population of ~1600 individuals. Integrative studies between zoo (ex situ) and wild (in situ) animals are crucial to modern conservation programs. They can demonstrate a substantial impact with the One Health concept, an interdisciplinary research frontier regarding the relations between human, animal, and environmental health. Studies of wild populations of Leontopithecus spp. are scarce and should be encouraged to provide baseline information to develop preventive and curative medicine in zoos and other conservation programs. Studying these animals in the wild can offer important reference parameters for the species. Comparing bacterial communities between in situ and ex situ populations can help us understand both conditions and the dynamics of potentially pathogenic microorganisms. To increase our understanding of resident microorganisms among these groups, we collected oral and rectal samples from captive (zoo) and wild black lion tamarins. We employed a culture method for the identification of aerobic bacteria. Thirty-three specimens were sampled (24 zoo and 8 wild animals) and 18 bacterial genera were identified. We found primarily Gram-positive bacteria in wild animals, whereas in zoo animals, Gram-negative bacteria were dominant. Some of the bacterial species we identified are potentially pathogenic, whereas several others are being reported here for the first time in this host species. Our results reinforce the importance of integrative studies for the future management and conservation of this endangered primate species.

Ceftolozane/tazobactam versus colistin in the treatment of ventilator-associated pneumonia due to extensively drug-resistant Pseudomonas aeruginosa

Resistant strains of Pseudomonas aeruginosa are common pathogens in the intensive care unit (ICU), limiting available therapeutic options. We aimed to compare ceftolozane/tazobactam (C/T) with colistimethate sodium (CMS) in the treatment of ventilator-associated pneumonia (VAP) due to extensively drug-resistant (XDR) Pseudomonas aeruginosa. A retrospective, observational study was performed at a tertiary care ICU. Clinical and microbiological success rate, 28-day all-cause mortality, and adverse events were compared in patients who received C/T with those treated with systemic CMS. A total of 51 patients were included (18 in the C/T and 33 in the CMS group). Clinical success rates in the C/T and CMS groups were 13 (72.2%) and 10 (30.3%), respectively. On multivariate regression analysis, treatment with C/T was independently associated with clinical success (odds ratio 4.47, 95% CI 1.17–17.08). There was no difference in 28-day all-cause mortality (27.8% and 33.3% in the C/T and CMS group, p = 0.76). Acute kidney injury was more common in patients who received CMS (48.5% vs 11.1%, p = 0.01). In our study, ceftolozane/tazobactam was more efficacious in the treatment of XDR Pseudomonas aeruginosa VAP and showed a better safety profile compared to CMS.

The changing pattern of bacterial and fungal respiratory isolates in patients with and without COVID-19 admitted to intensive care unit

Objectives

Severe acute respiratory syndrome 2 (SARS-CoV-2) pandemic has had a heavy impact on national health system, especially in the first wave. That impact hit principally the intensive care units (ICUs). The large number of patients requiring hospitalization in ICUs lead to a complete upheaval of intensive wards. The increase in bed, the fewer number of nurses per patient, the constant use of personal protective equipment, the new antimicrobial surveillance protocols could have had deeply effects on microbiological flora of these wards. Moreover, the overconsumption of antimicrobial therapy in COVID-19 patients, like several studies report, could have impact of this aspect. Aim of this study is to evaluate the changing pattern of microbiological respiratory isolates during and before COVID-19 pandemic in a tertiary hospital ICUs.

Methods

A retrospective, observational study was conducted in ICUs of “ASST Papa Giovanni XXIII”, a large tertiary referral hospital in Northern Italy. We have retrospectively collected the microbiological data from bronchoalveolar lavage (BAL) and tracheal aspirate (TA) of patients with COVID-19, hospitalized in ICUs from 22nd February 2020 to 31st May 2020 (Period 1), and without COVID-19, from 22nd February 2019 to 31st May 2019 (Period 2). We compared the prevalence and the antibiotic profile of bacterial and fungal species in the two time periods.

Results

The prevalence of Pseudomonas spp. shows a statistically significant increase from patients without COVID-19 compared to COVID-19 positive as well as the prevalence of Enterococcus spp. On the contrary, the prevalence of Gram negative non fermenting bacteria (GN-NFB), Haemophilus influenzae and Streptococcus pneumoniae showed a significant reduction between two periods. There was a statistically significant increase in resistance of Pseudomonas spp. to carbapenems and piperacillin/tazobactam and Enterobacterales spp. for piperacillin/tazobactam, in COVID-19 positive patients compared to patients without COVID-19. We did not observe significant changing in fungal respiratory isolates.

Conclusions

A changing pattern in prevalence and resistance profiles of bacterial and fungal species was observed during COVID-19 pandemic.

ECF Sigma Factor HxuI Is Critical for In Vivo Fitness of Pseudomonas aeruginosa during Infection

The opportunistic pathogen Pseudomonas aeruginosa often adapts to its host environment and causes recurrent nosocomial infections. The extracytoplasmic function (ECF) sigma factor enables bacteria to alter their gene expression in response to host environmental stimuli. Here, we report an ECF sigma factor, HxuI, which is rapidly induced once P. aeruginosa encounters the host. Host stresses such as iron limitation, oxidative stress, low oxygen, and nitric oxide induce the expression of hxuI. By combining RNA-seq and promoter-lacZ reporter fusion analysis, we reveal that HxuI can activate the expression of diverse metabolic and virulence pathways which are critical to P. aeruginosa infections, including iron acquisition, denitrification, pyocyanin synthesis, and bacteriocin production. Most importantly, overexpression of the hxuI in the laboratory strain PAO1 promotes its colonization in both murine lung and subcutaneous infections. Together, our findings show that HxuI, a key player in host stress-response, controls the in vivo adaptability and virulence of P. aeruginosa during infection. IMPORTANCE P. aeruginosa has a strong ability to adapt to diverse environments, making it capable of causing recurrent and multisite infections in clinics. Understanding host adaptive mechanisms plays an important guiding role in the development of new anti-infective agents. Here, we demonstrate that an ECFσ factor of P. aeruginosa response to the host-inflicted stresses, which promotes the bacterial in vivo fitness and pathogenicity. Furthermore, our findings may help explain the emergence of highly transmissible strains of P. aeruginosa and the acute exacerbations during chronic infections.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

Five-year Surveillance of Antimicrobial Resistance Changes and Epidemiological Characteristics in Pseudomonas aeruginosa: A Retrospective Study in a Chinese City Hospital

Background: In recent years, the widespread use of antibiotics has resulted in increased rates of antibiotic resistance (ABR). Pseudomonas aeruginosa is one of the most important opportunistic pathogens causing hospital-acquired infections. Pseudomonas aeruginosa has continuously increased resistance to commonly used clinical antimicrobial drugs, bringing great difficulties to clinical treatment. Objectives: This retrospective study investigated the epidemiological characteristics of P. aeruginosa and changes in ABR over a 5-year period at a hospital in Shandong Province, China. Methods: Pseudomonas aeruginosa strains were collected from 2015 to 2019. The antimicrobial susceptibility testing employed the Kirby-Bauer disk diffusion method and the broth microdilution method (VITEK-2 compact system), according to the guidelines by the Clinical and Laboratory Standards Institute. Data were analyzed using WHONET 5.6 and SPSS V. 21.0 software. Results: A total of 3,324 P. aeruginosa strains were isolated from clinical specimens (604, 631, 700, 595, and 794 strains from 2015 to 2019, respectively). The highest P. aeruginosa detection rates were from respiratory tract specimens (72.54%). The highest resistance was seen in aztreonam, followed by ciprofloxacin, levofloxacin, and imipenem. The isolation rates for carbapenem-resistant P. aeruginosa (CRPA) and multidrug-resistant P. aeruginosa (MDRPA) ranged from 15.21 - 18.38% and 17.31 - 27.31%, respectively. Also, the isolation rates for extensively drug-resistant P. aeruginosa (XDRPA) ranged from 1.86 - 3.52%. Conclusions: The main sources of the P. aeruginosa isolates were older adult patients with chronic respiratory diseases. The isolation rates for CRPA, MDRPA, and XDRPA strains decreased over the 5-year period. However, the drug resistance situation remains a serious concern. Hence, continued infection control and antimicrobial stewardship and basic and clinical research on bacterial resistance are essential.

Association between antibiotic resistance in intensive care unit (ICU)-acquired infections and excess resource utilization: Evidence from Spain, Italy, and Portugal

BACKGROUND

Intensive care unit (ICU)-acquired infections with antibiotic-resistant bacteria have been associated with substantial health and economic costs. Moreover, southern Europe has historically reported high levels of antimicrobial resistance.

OBJECTIVES

We estimated the attributable economic burden of ICU-acquired infections due to resistant bacteria based upon hospital excess length of stay (LOS) in a selected sample of southern European countries.

METHODS

We studied a cohort of adult patients admitted to the ICU who developed an ICU-acquired infection related to an invasive procedure in a sample of Spanish, Italian, and Portuguese hospitals between 2008 and 2016, using data from The European Surveillance System (TESSy) released by the European Centers for Disease Control (ECDC). We analyzed the association between infections with selected antibiotic-resistant bacteria of public health importance and excess LOS using regression, matching, and time-to-event methods. We controlled for several confounding factors as well as time-dependent biases. We also computed the associated economic burden of excess resource utilization for each selected country.

RESULTS

In total, 13,441 patients with at least 1 ICU-acquired infection were included in the analysis: 4,106 patients (30.5%) were infected with antimicrobial-resistant bacteria, whereas 9,335 patients (69.5%) were infected with susceptible bacteria. The unadjusted association between resistance status and excess LOS was 7 days (95% CI, 6.13-7.87; P < .001). Fully adjusted models yielded significantly lower estimates: 2.76 days (95% CI, 1.98-3.54; P < .001) in the regression model, 2.60 days (95% CI, 1.66-3.55; P < .001) in the genetic matching model, and a hazard ratio of 1.15 (95% CI, 1.11-1.19; P < .001) in the adjusted Cox regression model. These estimates, alongside the prevalence of resistance, translated into direct hospitalization attributable costs per ICU-acquired infection of 5,224€ (95% CI, 3,691-6,757) for Spain, 4,461€ (95% CI, 1,948-6,974) for Portugal, and 4,320€ (95% CI, 1,662-6,977) for Italy.

CONCLUSIONS

ICU-acquired infections associated with antibiotic-resistant bacteria are substantially associated with a 15% increase in excess LOS and resource utilization in 3 southern European countries. However, failure to appropriately control for significant confounders inflates estimates by ∼2.5-fold.

Genomic Analysis of Carbapenem-Resistant Pseudomonas aeruginosa Isolated From Urban Rivers Confirms Spread of Clone Sequence Type 277 Carrying Broad Resistome and Virulome Beyond the Hospital

The dissemination of antibiotic-resistant priority pathogens beyond hospital settings is both a public health and an environmental problem. In this regard, high-risk clones exhibiting a multidrug-resistant (MDR) or extensively drug-resistant (XDR) phenotype have shown rapid adaptation at the human-animal-environment interface. In this study, we report genomic data and the virulence potential of the carbapenemase, São Paulo metallo-β-lactamase (SPM-1)-producing Pseudomonas aeruginosa strains (Pa19 and Pa151) isolated from polluted urban rivers, in Brazil. Bioinformatic analysis revealed a wide resistome to clinically relevant antibiotics (carbapenems, aminoglycosides, fosfomycin, sulfonamides, phenicols, and fluoroquinolones), biocides (quaternary ammonium compounds) and heavy metals (copper), whereas the presence of exotoxin A, alginate, quorum sensing, types II, III, and IV secretion systems, colicin, and pyocin encoding virulence genes was associated with a highly virulent behavior in the Galleria mellonella infection model. These results confirm the spread of healthcare-associated critical-priority P. aeruginosa belonging to the MDR sequence type 277 (ST277) clone beyond the hospital, highlighting that the presence of these pathogens in environmental water samples can have clinical implications for humans and other animals.

A pipeline to evaluate inhibitors of the Pseudomonas aeruginosa exotoxin U

Pseudomonas aeruginosa has recently been highlighted by the World Health Organisation (WHO) as a major threat with high priority for the development of new therapies. In severe P. aeruginosa infections, the phospholipase activity of the type 3 secretion system toxin, ExoU, induces lysis of target host cells and results in the poorest clinical outcomes. We have developed an integrated pipeline to evaluate small molecule inhibitors of ExoU in vitro and in cultured cell models, including a disease-relevant corneal epithelial (HCE-T) scratch and infection model using florescence microscopy and cell viability assays. Compounds Pseudolipasin A, compound A and compound B were effective in vitro inhibitors of ExoU and mitigated P. aeruginosa ExoU-dependent cytotoxicity after infection of HCE-T cells at concentrations as low as 0.5 µM. Addition of the antimicrobial moxifloxacin controlled bacterial load, allowing these assays to be extended from 6 h to 24 h. P. aeruginosa remained cytotoxic to HCE-T cells with moxifloxacin, present at the minimal inhibitory concentration for 24 h, but, when used in combination with either Pseudolipasin A, compound A or compound B, a greater amount of viable cells and scratch healing were observed. Thus, our pipeline provides evidence that ExoU inhibitors could be used in combination with certain antimicrobials as a novel means to treat infections due to ExoU producing P. aeruginosa, as well as the means to identify more potent ExoU inhibitors for future therapeutics.

Role of CD44 in increasing the potency of mesenchymal stem cell extracellular vesicles by hyaluronic acid in severe pneumonia

Background

Although promising, clinical translation of human mesenchymal stem or stromal cell-derived extracellular vesicles (MSC EV) for acute lung injury is potentially limited by significant production costs. The current study was performed to determine whether pretreatment of MSC EV with high molecular weight hyaluronic acid (HMW HA) would increase the therapeutic potency of MSC EV in severe bacterial pneumonia.

Methods

In vitro experiments were performed to determine the binding affinity of HMW HA to MSC EV and its uptake by human monocytes, and whether HMW HA primed MSC EV would increase bacterial phagocytosis by the monocytes. In addition, the role of CD44 receptor on MSC EV in the therapeutic effects of HMW HA primed MSC EV were investigated. In Pseudomonas aeruginosa (PA) pneumonia in mice, MSC EV primed with or without HMW HA were instilled intravenously 4 h after injury. After 24 h, the bronchoalveolar lavage fluid, blood, and lungs were analyzed for levels of bacteria, inflammation, MSC EV trafficking, and lung pathology.

Results

MSC EV bound preferentially to HMW HA at a molecular weight of 1.0 MDa compared with HA with a molecular weight of 40 KDa or 1.5 MDa. HMW HA primed MSC EV further increased MSC EV uptake and bacterial phagocytosis by monocytes compared to treatment with MSC EV alone. In PA pneumonia in mice, instillation of HMW HA primed MSC EV further reduced inflammation and decreased the bacterial load by enhancing the trafficking of MSC EV to the injured alveolus. CD44 siRNA pretreatment of MSC EV prior to incubation with HMW HA eliminated its trafficking to the alveolus and therapeutic effects.

Conclusions

HMW HA primed MSC EV significantly increased the potency of MSC EV in PA pneumonia in part by enhancing the trafficking of MSC EV to the sites of inflammation via the CD44 receptor on MSC EV which was associated with increased antimicrobial activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02329-2.

Efficacy of human-simulated bronchopulmonary exposures of cefepime, zidebactam and the combination (WCK 5222) against MDR Pseudomonas aeruginosa in a neutropenic murine pneumonia model

OBJECTIVES

WCK 5222 combines cefepime with zidebactam, a β-lactam enhancer that binds PBP2 and inhibits class A and C β-lactamases. The efficacy of human-simulated bronchopulmonary exposures of WCK 5222 against MDR Pseudomonas aeruginosa was investigated in a neutropenic murine pneumonia model.

METHODS

Nineteen MDR isolates of P. aeruginosa (cefepime MICs ≥64 mg/L) were studied. MICs of zidebactam and WCK 5222 ranged from 4 to 512 mg/L and from 4 to 32 mg/L, respectively. Dosing regimens of cefepime and zidebactam alone and in combination that achieved epithelial lining fluid (ELF) exposures in mice approximating human ELF exposures after doses of 2 g of cefepime/1 g of zidebactam every 8 h (1 h infusion) were utilized; controls were vehicle-dosed. Lungs were intranasally inoculated with 107-108 cfu/mL bacterial suspensions. Mice were dosed subcutaneously 2 h after inoculation for 24 h, then lungs were harvested.

RESULTS

In vitro MIC was predictive of in vivo response to WCK 5222 treatment. Mean±SD changes in bacterial density at 24 h compared with 0 h controls (6.72±0.50 log10 cfu/lungs) for 13 isolates with WCK 5222 MICs ≤16 mg/L were 1.17±1.00, -0.99±1.45 and -2.21±0.79 log10 cfu/lungs for cefepime, zidebactam and WCK 5222, respectively. Against these isolates, zidebactam yielded >1 log10 cfu/lungs reductions in 8/13, while activity was enhanced with WCK 5222, producing >2 log10 cfu/lungs reductions in 10/13 and >1 log10 cfu/lungs reductions in 12/13. Among isolates with WCK 5222 MICs of 32 mg/L, five out of six showed a bacteriostatic response.

CONCLUSIONS

Human-simulated bronchopulmonary exposure of WCK 5222 is effective against MDR P. aeruginosa at MIC ≤16 mg/L in a murine pneumonia model. These data support the clinical development of WCK 5222 for pseudomonal lung infections.

Pseudomonas aeruginosa: An Audacious Pathogen with an Adaptable Arsenal of Virulence Factors

Pseudomonas aeruginosa is a dominant pathogen in people with cystic fibrosis (CF) contributing to morbidity and mortality. Its tremendous ability to adapt greatly facilitates its capacity to cause chronic infections. The adaptability and flexibility of the pathogen are afforded by the extensive number of virulence factors it has at its disposal, providing P. aeruginosa with the facility to tailor its response against the different stressors in the environment. A deep understanding of these virulence mechanisms is crucial for the design of therapeutic strategies and vaccines against this multi-resistant pathogen. Therefore, this review describes the main virulence factors of P. aeruginosa and the adaptations it undergoes to persist in hostile environments such as the CF respiratory tract. The very large P. aeruginosa genome (5 to 7 MB) contributes considerably to its adaptive capacity; consequently, genomic studies have provided significant insights into elucidating P. aeruginosa evolution and its interactions with the host throughout the course of infection.

Airway immunometabolites fuel Pseudomonas aeruginosa infection

Pulmonary infections are associated with a brisk inflammatory reaction to bacterial surface components. Lipopolysaccharides (LPS) trigger macrophage activation and release of mitochondrial metabolites that control the intensity of the immune response. Whereas succinate induces oxidative stress (ROS), HIF1α stabilization, glycolysis and IL-1β release, itaconate suppresses inflammation by inhibiting succinate oxidation, glycolytic flux and promoting anti-oxidant Nrf2-HO-1 functions. P. aeruginosa is a major pathogen associated with acute and chronic lung infection. Although both secreted toxins, LPS and proteases are key factors to establish acute P. aeruginosa pneumonia, lack of these components in chronic P. aeruginosa isolates suggest these organisms exploit other mechanisms to adapt and persist in the lung. Upon inhalation, P. aeruginosa strains trigger airway macrophage reprograming and bacterial variants obtained from acutely and chronically infected subjects exhibit metabolic adaptation consistent with succinate and itaconate assimilation; namely, high expression of extracellular polysaccharides (EPS), reduced lptD-LPS function, increased glyoxylate shunt (GS) activity and substantial biofilm production. In this review we discuss recent findings illustrating how P. aeruginosa induces and adapts to macrophage metabolites in the human lung, and that catabolism of succinate and itaconate contribute to their formidable abilities to tolerate oxidative stress, phagocytosis and immune clearance.

Rapid detection of carbapenemase-producing Pseudomonas spp. using the NitroSpeed-Carba NP test

The NitroSpeed-Carba NP test was used to rapidly detect and discriminate between the different types of carbapenemases (classes A, B, and D) within 30 minutes among a collection of 202 Pseudomonas sp. strains (mostly Pseudomonas aeruginosa). A total of 99 carbapenemase-(including enzymes exhibiting weak carbapenemase activity such as several Guyana Extended-Spectrum (GES)-ß-lactamases) and 103 non-carbapenemase producers were tested, and the overall specificity and sensitivity were 100% and 99%, respectively. The NitroSpeed-Carba NP test is a rapid, specific, sensitive, and easy-to-implement technique for identification of carbapenemase-producing Pseudomonas spp.

Identification of Streptococcus pneumoniae in hospital-acquired pneumonia in adults

Hospital-acquired pneumonia (HAP) is often more severe and life-threatening than community-acquired pneumonia (CAP). The role of Streptococcus pneumoniae in CAP is well-understood, but its role in HAP is unclear. The objective of this study was to summarize the available literature on the prevalence of S. pneumoniae in HAP episodes. We searched MEDLINE for peer-reviewed articles on the microbiology of HAP in individuals aged ≥18 years, published between 2008 and 2018. We calculated pooled estimates of the prevalence of S. pneumoniae in episodes of HAP using a random-effects, inverse-variance-weighted meta-analysis. Forty-seven of 1908 articles met the inclusion criteria. Bacterial specimen isolation techniques for microbiologically defined HAP episodes included bronchoalveolar lavage, protective specimen brush, tracheobronchial aspirate and sputum, as well as blood culture. Culture was performed in all studies; five studies also used urine antigen detection (5/47; 10.6%). S. pneumoniae was identified in 5.1% (95% confidence interval (CI): 3.8-6.6%) of microbiologically defined HAP episodes (N = 20), with 5.4% (95% CI: 4.3-6.7%, N = 29) in ventilator-associated HAP and 6.0% (95% CI: 4.1-8.8%, N = 6) in non-ventilator-associated HAP. S. pneumoniae was identified in 5.3% (95% CI: 4.5-6.3%) of HAP occurring in the intensive care unit (ICU, N = 41) and in 5.6% (95% CI: 3.3-9.5%, N = 5) outside the ICU. A higher proportion of early-onset HAP (10.3%; 95% CI: 8.3-12.8%, N = 16) identified S. pneumoniae as compared with late-onset HAP (3.3%; 95% CI: 2.5-4.4%, N = 16). In conclusion, S. pneumoniae was identified by culture in 5.1% of microbiologically defined HAP episodes. The importance of HAP as part of the disease burden caused by S. pneumoniae merits further research.

Clinical and microbiological characteristics of adults with hospital-acquired pneumonia: a 10-year prospective observational study in China

Hospital-acquired pneumonia (HAP) is a significant nosocomial infection; data on the distribution and antimicrobial resistance profiles of HAP in China are limited. We included 2827 adult patients with HAP from the Chinese Antimicrobial Resistance Surveillance of Nosocomial Infections network admitted in 15 Chinese teaching hospitals between 2007 and 2016. Clinical data and antimicrobial susceptibility of isolated pathogens were obtained from the medical records and central laboratory, respectively. Multivariable logistic regression was performed to determine the risk factors for mortality and multidrug resistance (MDR). A total of 386 (13.7%) patients died in the hospital, while 1181 (41.8%) developed ventilator-associated pneumonia (VAP). Active immunosuppressant therapy (OR 1.915 (95% CI 1.475-2.487)), solid tumor (OR 1.860 (95% CI 1.410-2.452)), coma (OR 1.783 (95% CI 1.364-2.333)), clinical pulmonary infection score ≥7 (OR 1.743 (95% CI 1.373-2.212)), intensive care unit stay (OR 1.652 (95% CI 1.292-2.111)), age ≥65 years (OR 1.621 (95% CI 1.282-2.049)), and tracheal cannula insertion (OR 1.613 (95% CI 1.169-2.224)) were independent risk factors for in-hospital mortality. Liver cirrhosis (OR 3.120 (95% CI 1.436-6.780)) and six other variables were independent predictors of MDR. Acinetobacter baumannii (25.6%), Pseudomonas aeruginosa (20.1%), Klebsiella pneumoniae (15.4%), and Staphylococcus aureus (12.6%) were the most common pathogens (MDR prevalence 64.9%). Isolates from VAP patients showed more A. baumannii and less K. pneumoniae and E. coli strains (p < 0.001, respectively) than those from patients without VAP. The proportion of methicillin-resistant S. aureus strains decreased; that of carbapenem-resistant A. baumannii and Enterobacterales strains increased. There had been changes in the antibiotic resistance profiles of HAP pathogens in China. Risk factors for mortality and MDR are important for the selection of antimicrobials for HAP in China.

Pseudomonas aeruginosa infection in intensive care: Epidemiology, outcomes, and antimicrobial susceptibilities

BACKGROUND

Pseudomonas aeruginosa (PA) infection in the intensive care unit (ICU) contributes to substantial mortality. In this study, we describe the epidemiology, antimicrobial susceptibilities, and outcomes of ICU patients with pseudomonal infection.

METHODS

ICU patients with PA were identified and classified as colonized or infected. Infected patients were reviewed for source, patient characteristics, antimicrobial susceptibilities, appropriateness of empiric antimicrobial therapy, and 30-day mortality. Independent predictors of mortality were identified using multivariable logistic regression.

RESULTS

One hundred forty (71%) patients with PA were infected. Mean patient age was 55 (SD 18) years; 62% were male. Admission categories included medical (71%), surgical (20%), and trauma or neurological (9%). Mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was 19 (SD 10). One hundred twenty-six (90%) patients were mechanically ventilated, 102 (73%) required vasopressors, and 27 (19%) received renal replacement; 32 (23%) died within 30 days. Infection was nosocomial in 101 (72%) cases. Sources were respiratory (66%), skin-soft tissue (11%), urinary (10%), blood (5%), surgical (5%), gastrointestinal (2%), or unknown (1%). Twenty (14%) isolates were multi-drug resistant; 6 (4%) were extensively drug resistant. Empiric antimicrobial therapy was effective in 97 (69%) cases. Liver disease (adjusted OR [aOR] 6.2, 95% CI 1.5 to 25.7; p = 0.01), malignancy (aOR 5.0, 95% CI 1.5 to 17.3; p = 0.01), and higher APACHE II score (aOR 1.1, 95% CI 1.0 to 1.1; p = 0.02) were independently associated with 30-day mortality.

CONCLUSIONS

PA infection in ICU is most commonly respiratory and associated with substantial mortality. Existing malignancy, liver disease, and higher APACHE II score were independently associated with mortality.

Antimicrobial Activity of Colistin Against Contemporary (2015 – 2017) P. aeruginosa and A. baumannii Isolates From a Chinese Surveillance Program

Objective

To investigate the incidence and susceptibilities of non-fermenting bacteria isolates from Chinese respiratory (RTI), intra-abdominal (IAI) and urinary tract (UTI) infections to antimicrobial agents between 2015 and 2017.

Methods

In total, 3,246 non-fermentative bacteria were collected from 21 hospitals and 9 hospital departments across 7 regions of China. A central testing laboratory was employed to determine antimicrobial susceptibilities using appropriate standards of interpretation.

Results

The majority of the isolates were Acinetobacter baumannii (n = 1,360, 41.9%) and Pseudomonas aeruginosa (n = 1,341, 41.3%). Overall multidrug resistance (MDR) and carbapenem resistance (CR) rates of Acinetobacter baumannii were 80.1 and 78.7% with MDR and CR rates in RTIs, IAIs, and UTIs of 82.0 and 81.0%, 82.6 and 81.0% as well as 53.1 and 46.9%. Overall MDR and CR rates of Pseudomonas aeruginosa isolates were 36.2 and 38.9% with 41.8 and 44.3%, 29.3 and 36.1% as well as 24.2 and 20.2% MDR and CR rates in RTIs, IAIs, and UTIs. Overall susceptibility rates to imipenem, meropenem, amikacin, ciprofloxacin, cefepime and piperacillin-tazobactam were 21.1, 21.3, 33.0, 18.4, 19.2, and 19.6% for Acinetobacter baumannii and 56.5, 58.5, 88.4, 63.1, 63.1, and 55.63% for Pseudomonas aeruginosa isolates, whereas for colistin they were 95.7 and 94.6%, respectively. In all departments and regions of China, susceptibility rates of Pseudomonas aeruginosa and Acinetobacter baumannii isolates to colistin were constantly above 80%.

Conclusion

Due to the high MDR and CR rates for Pseudomonas aeruginosa and Acinetobacter baumannii, isolates obtained from RTIs, IAIs, and UTIs only maintained high susceptibility rates to colistin between 2015 and 2017.

Pharmacoinformatics approaches to identify potential hits against tetraacyldisaccharide 4'-kinase (LpxK) of Pseudomonas aeruginosa

Pseudomonas aeruginosa infection can cause pneumonia and urinary tract infection and the management of Pseudomonas aeruginosa infection is critical in multidrug resistance, hospital-acquired bacteremia and ventilator-associated pneumonia. The key enzymes of lipid A biosynthesis in Pseudomonas aeruginosa are promising drug targets. However, the enzyme tetraacyldisaccharide 4'-kinase (LpxK) has not been explored as a drug target so far. Several pharmacoinformatics tools such as comparative metabolic pathway analysis (Metacyc), data mining from a database of essential genes (DEG), homology modeling, molecular docking, pharmacophore based virtual screening, ADMET prediction and molecular dynamics simulation were used in identifying novel lead compounds against this target. The top virtual hits STOCK6S-33288, 43621, 39892, 37164 and 35740 may serve as the templates for the design and synthesis of potent LpxK inhibitors in the management of serious Pseudomonas aeruginosa infection.

An overview of guidelines for the management of hospital-acquired and ventilator-associated pneumonia caused by multidrug-resistant Gram-negative bacteria

PURPOSE OF REVIEW

Multidrug-resistant (MDR) Gram-negative pathogens in hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are associated with poor clinical outcomes. These pathogens represent a global threat with few therapeutic options. In this review, we discuss current guidelines for the empiric management of HAP/VAP caused by MDR Gram-negative pathogens.

RECENT FINDINGS

The incidence of MDR Gram-negative bacteria is rising among cases of nosocomial pneumonia, such that it is now becoming a significant challenge for clinicians. Adherence to international guidelines may ensure early and adequate antimicrobial therapy, guided by local microbiological data and awareness of the risk factors for MDR bacteria.

SUMMARY

Due to the increasing prevalence of HAP/VAP caused by MDR Gram-negative pathogens, management should be guided by the local ecology and the patient's risk factors for MDR pathogens. The main risk factors are prior hospitalization for at least 5 days, prior use of broad-spectrum antibiotics, prior colonization with resistant pathogens, admission to hospital settings with high rates of MDR pathogens, and septic shock at the time of diagnosis with nosocomial pneumonia.

Risk Factors of Multidrug-Resistant Bacteria in Lower Respiratory Tract Infections: A Systematic Review and Meta-Analysis

Background

Multidrug-resistant (MDR) bacteria are the main cause of lower respiratory tract infections (LRTIs) with high mortality. The purpose of this study is to identify the risk factors associated with MDR by performing a systematic review and meta-analysis.

Methods

PubMed, EMBASE (via Ovid), and Cochrane Library were systematically searched for studies on the risk factors for MDR bacteria in LRTIs as of November 30, 2019. Literature screening, data abstraction, and quality assessment of the eligible studies were performed independently by two researchers.

Results

A total of 3,607 articles were retrieved, of which 21 articles representing 20 cohort studies published in English were included after title/abstract and full-text screening. Among the 21 articles involving 7,650 patients and 1,360 MDR organisms, ten reported the risk factors for MDR Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), ten for MDR GNB, and one for MDR GPB. The meta-analysis results suggested that prior antibiotic treatment, inappropriate antibiotic therapy, chronic lung disease, chronic liver disease and cerebral disease, prior MDR and PA infection/colonization, recent hospitalization, longer hospitalization stay, endotracheal tracheostomy and mechanical ventilation, tube feeding, nursing home residence, and higher disease severity score were independent risk factors for MDR bacteria.

Conclusions

This review identified fourteen clinical factors that might increase the risk of MDR bacteria in patients with LRTIs. Clinicians could take into account these factors when selecting antibiotics for patients and determine whether coverage for MDR bacteria is required. More well-designed studies are needed to confirm the various risk factors for MDR bacteria in the future.

Update of the treatment of nosocomial pneumonia in the ICU

In accordance with the recommendations of, amongst others, the Surviving Sepsis Campaign and the recently published European treatment guidelines for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), in the event of a patient with such infections, empirical antibiotic treatment must be appropriate and administered as early as possible. The aim of this manuscript is to update treatment protocols by reviewing recently published studies on the treatment of nosocomial pneumonia in the critically ill patients that require invasive respiratory support and patients with HAP from hospital wards that require invasive mechanical ventilation. An interdisciplinary group of experts, comprising specialists in anaesthesia and resuscitation and in intensive care medicine, updated the epidemiology and antimicrobial resistance and established clinical management priorities based on patients' risk factors. Implementation of rapid diagnostic microbiological techniques available and the new antibiotics recently added to the therapeutic arsenal has been reviewed and updated. After analysis of the categories outlined, some recommendations were suggested, and an algorithm to update empirical and targeted treatment in critically ill patients has also been designed. These aspects are key to improve VAP outcomes because of the severity of patients and possible acquisition of multidrug-resistant organisms (MDROs).

Association between sepsis at ICU admission and mortality in patients with ICU-acquired pneumonia: An infectious second-hit model

PURPOSE

We explore the hypothesis that critically ill patients developing ICU-acquired pneumonia (ICU-AP) have worse outcomes and an altered inflammatory response if their ICU admission was sepsis-related.

METHODS

Prospective cohort study in two centers. Patients with ICU-AP were evaluated according to their previous exposure to sepsis at ICU-admission. Demographic variables, comorbidities, severity scores at admission and at the time of acquisition of ICU-AP, and serum biomarkers of the inflammatory response were evaluated.

PRIMARY OUTCOME

90-day mortality.

SECONDARY OUTCOMES

ICU and hospital length of stay, mortality at days 28 and 180, in-hospital mortality, ventilator-free days (day-28), and inflammatory response. Propensity scoring weighted the risk of previously-acquired sepsis. Multivariate analysis evaluated the risk of mortality by day-90. Sensitivity analyses evaluated the primary outcome in different subgroups.

RESULTS

Of 341 patients enrolled, 147 had sepsis on ICU-admission. Adjusted risk of mortality at 90 days did not differ overall [hazard ratio (HR) = 0.94(CI:0.65-1.37)], nor in subpopulations with a confirmed etiology of pneumonia [HR = 0.93(CI:0.57-1.53)] or sepsis [HR = 0.91(0.54-1.55)], ventilator-associated pneumonia (VAP) [HR = 1.01(CI:0.61-1.68)], nor non-VAP ICU-AP [HR = 0.83(CI:0.40-1.71)]. No differences were found in clinical secondary outcomes, the inflammatory response was similar.

CONCLUSIONS

Previous sepsis does not appear to predispose to higher mortality nor worse outcomes in patients who develop ICU-acquired pneumonia.

Pseudomonas aeruginosa Utilizes Host-Derived Itaconate to Redirect Its Metabolism to Promote Biofilm Formation

The bacterium Pseudomonas aeruginosa is especially pathogenic, often being associated with intractable pneumonia and high mortality. How P. aeruginosa avoids immune clearance and persists in the inflamed human airway remains poorly understood. In this study, we show that P. aeruginosa can exploit the host immune response to maintain infection. Notably, unlike other opportunistic bacteria, we found that P. aeruginosa alters its metabolic and immunostimulatory properties in response to itaconate, an abundant host-derived immunometabolite in the infected lung. Itaconate induces bacterial membrane stress, resulting in downregulation of lipopolysaccharides (LPS) and upregulation of extracellular polysaccharides (EPS). These itaconate-adapted P. aeruginosa accumulate lptD mutations, which favor itaconate assimilation and biofilm formation. EPS, in turn, induces itaconate production by myeloid cells, both in the airway and systemically, skewing the host immune response to one permissive of chronic infection. Thus, the metabolic versatility of P. aeruginosa needs to be taken into account when designing therapies.

Photodynamic Activity on Biofilm in Endotracheal Tubes of Patients Admitted to an Intensive Care Unit

Ventilator-associated pneumonia (VAP) is an infection that arises after endotracheal intubation affecting patients under intensive care. The presence of the endotracheal tube (ETT) is a risk factor since it is colonized by multispecies biofilm. Antimicrobial photodynamic therapy (aPDT) could be a strategy to decontaminate ETTs. We verify if methylene blue (MB) associated with external illumination of the ETT could be an alternative to destroy biofilm. We performed an in vitro and ex vivo study. In vitro study was performed with P. aeruginosa biofilm grew over ETT for 7 days. After treatment, the surviving cells were cultured for 3 days and the biofilm was analyzed by crystal violet absorbance. Ex vivo study employed ETT obtained from extubated patients. aPDT was performed with MB (100 µm) and red LED (λ = 640±20 nm). We quantified the biofilm thickness and used scanning electron microscopy and fluorescence technique to verify morphological and functional changes after aPDT. Our results showed that bacteria remain susceptible to aPDT after sequential treatments. We also attested that aPDT can reduce biofilm thickness, disrupt biofilm attachment from ETT surface and kill microbial cells. These data suggest that aPDT should be investigated to decrease VAP incidence via ETT decontamination.

Epidemiology, Treatment, and Prevention of Nosocomial Bacterial Pneumonia

Septicaemia likely results in high case-fatality rates in the present multidrug-resistant (MDR) era. Amongst them are hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), two frequent fatal septicaemic entities amongst hospitalised patients. We reviewed the PubMed database to identify the common organisms implicated in HAP/VAP, to explore the respective risk factors, and to find the appropriate antibiotic choice. Apart from methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, extended-spectrum β-lactamase-producing Enterobacteriaceae spp., MDR or extensively drug-resistant (XDR)-Acinetobacter baumannii complex spp., followed by Stenotrophomonas maltophilia, Chryseobacterium indologenes, and Elizabethkingia meningoseptica are ranked as the top Gram-negative bacteria (GNB) implicated in HAP/VAP. Carbapenem-resistant Enterobacteriaceae notably emerged as an important concern in HAP/VAP. The above-mentioned pathogens have respective risk factors involved in their acquisition. In the present XDR era, tigecycline, colistin, and ceftazidime-avibactam are antibiotics effective against the Klebsiella pneumoniae carbapenemase and oxacillinase producers amongst the Enterobacteriaceae isolates implicated in HAP/VAP. Antibiotic combination regimens are recommended in the treatment of MDR/XDR-P. aeruginosa or A. baumannii complex isolates. Some special patient populations need prolonged courses (>7-day) and/or a combination regimen of antibiotic therapy. Implementation of an antibiotic stewardship policy and the measures recommended by the United States (US) Institute for Healthcare were shown to decrease the incidence rates of HAP/VAP substantially.

Impact of multi-drug resistant bacteria on economic and clinical outcomes of healthcare-associated infections in adults: Systematic review and meta-analysis

Background

Infections with multidrug resistant (MDR) bacteria in hospital settings have substantial implications in terms of clinical and economic outcomes. However, due to clinical and methodological heterogeneity, estimates about the attributable economic and clinical effects of healthcare-associated infections (HAI) due to MDR microorganisms (MDR HAI) remain unclear. The objective was to review and synthesize the evidence on the impact of MDR HAI in adults on hospital costs, length of stay, and mortality at discharge.

Methods and findings

Literature searches were conducted in PubMed/MEDLINE, and Google Scholar databases to select studies that evaluated the impact of MDR HAI on economic and clinical outcomes. Eligible studies were conducted in adults, in order to ensure homogeneity of populations, used propensity score matched cohorts or included explicit confounding control, and had confirmed antibiotic susceptibility testing. Risk of bias was evaluated, and effects were measured with ratios of means (ROM) for cost and length of stay, and risk ratios (RR) for mortality. A systematic search was performed on 14^th March 2019, re-run on the 10^th of June 2019 and extended the 3^rd of September 2019. Small effect sizes were assessed by examination of funnel plots. Sixteen articles (6,122 patients with MDR HAI and 8,326 patients with non-MDR HAI) were included in the systematic review of which 12 articles assessed cost, 19 articles length of stay, and 14 mortality. Compared to susceptible infections, MDR HAI were associated with increased cost (ROM 1.33, 95%CI [1.15; 1.54]), prolonged length of stay (ROM 1.27, 95%CI [1.18; 1.37]), and excess in-hospital mortality (RR 1.61, 95%CI [1.36; 1.90]) in the random effects models. Risk of publication bias was only found to be significant for mortality, and overall study quality good.

Conclusions

MDR HAI appears to be strongly associated with increases in direct cost, prolonged length of stay and increased mortality. However, further comprehensive studies in this setting are warranted.

Trial registration

PROSPERO (CRD42019126288).