Antimicrobial combination treatment including ciprofloxacin decreased the mortality rate of Pseudomonas aeruginosa bacteraemia: a retrospective cohort study

Antipseudomonal cephalosporins versus piperacillin/tazobactam or carbapenems for the definitive antibiotic treatment of Pseudomonas aeruginosa bacteraemia: new kids on the ICU block?

BACKGROUND

Pseudomonas aeruginosa bloodstream infections (Pa-BSIs) are still a major cause of mortality in ICUs, posing many treatment uncertainties.

METHODS

This multicentre, retrospective study analysed data from 14 Italian hospitals, including all consecutive adults developing Pa-BSI in ICU during 2021-22 and treated with antibiotics for at least 48 h. The primary aim was to identify predictors of 30 day mortality using Cox regression. Results were adjusted with inverse probability of treatment weighting (IPTW) and for immortal time bias.

RESULTS

Overall, 170 patients were included. High-risk BSI (source: lung, intra-abdominal, CNS) occurred in 118 (69%) patients, and 54 (32%) had septic shock. In 37 (22%), 73 (43%), 12 (7%) and 48 (28%) the definitive backbone therapy was piperacillin/tazobactam, carbapenems, colistin or new antipseudomonal cephalosporins (ceftolozane/tazobactam, n = 20; ceftazidime/avibactam, n = 22; cefiderocol, n = 6), respectively. Moreover, 58 (34%) received a second drug as combination therapy. The incidence of 30 day all-cause mortality was 27.6% (47 patients). By Cox regression, Charlson comorbidity index, neutropenia, septic shock and high-risk BSI were independent predictors of 30 day mortality, while previous colonization by P. aeruginosa, use of antipseudomonal cephalosporins as definitive treatment, and combination therapy were shown to be protective. However, after IPTW adjustment, only the protective effect of antipseudomonal cephalosporins was confirmed (adjusted HR = 0.27, 95% CI = 0.10-0.69), but not for combination therapy. Hence, the treatment effect was calculated: antipseudomonal cephalosporins significantly reduced mortality risk [-17% (95% CI = -4% to -30%)], while combination therapy was beneficial only in the case of septic shock [-66% (95% CI = -44% to -88%].

CONCLUSIONS

In ICU, antipseudomonal cephalosporins may be the preferred target therapy for the treatment of Pa-BSI; in addition, initial combination therapy may be protective in the case of septic shock.

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.

Multicenter Surveillance of Pseudomonas aeruginosa Isolates From Blood: Clinical Distribution Characteristics and Antibiotic Resistance Trends in Hebei Province, China (2016-2021)

Purpose

To analyze the clinical distribution and antimicrobial resistance of Pseudomonas aeruginosa (P. aeruginosa) isolated from blood specimens in 75 hospitals in Hebei Province from 2016 to 2021 to aid in the rational selection of antimicrobial drugs.

Patients and Methods

WHONET 5.6 and SPSS 24.0 were used to retrospectively analyze clinical distribution characteristics and variations in drug-resistance.

Results

Between 2016 and 2021, 2208 P. aeruginosa strains were detected in blood specimens from Hebei Province. The median age of the patients with isolated P. aeruginosa was 63 years, with a male-to-female ratio of 2.1:1. Predominantly, patients were in the hematology (20.7%) and critical care medicine (18.4%) departments. During the monitoring period, the resistance rate of P. aeruginosa to various antibacterial drugs, such as aminoglycosides, fluoroquinolones, and carbapenems, decreased to varying degrees, with an average resistance rate of less than 20.0% over six years. Resistance rates were notably higher in pediatric and intensive care medicine, particularly in neonatal patients, where resistance to antimicrobial drugs, such as piperacillin/tazobactam, gentamicin, ciprofloxacin, and levofloxacin, exceeded 75%.

Conclusion

The main isolates of P. aeruginosa were from elderly and intensive care patients, with a male predominance. From 2016 to 2021, the resistance rate of P. aeruginosa isolated from blood specimens in Hebei Province to various antibiotics such as aminoglycosides, fluoroquinolones, and carbapenems decreased to varying degrees. The resistance rates are high in pediatric and intensive care medicine, especially among neonatal patients. However, resistance to antibiotics varies with age and department, necessitating tailored antimicrobial administration. The issue of antibacterial drug resistance in newborn patients is concerning, and special attention is needed when during treatment.

Effect of empiric antibiotics against Pseudomonas aeruginosa on mortality in hospitalized patients: a systematic review and meta-analysis

BACKGROUND

Empiric antibiotics active against Pseudomonas aeruginosa are recommended by professional societies for certain infections and are commonly prescribed for hospitalized patients. The effect of this practice on mortality is uncertain.

METHODS

A systematic literature search was conducted using Embase, Medline, PubMed, Web of Science, Cochrane, Scopus and Google Scholar from earliest entry through 9 October 2023. We included studies of patients hospitalized with P. aeruginosa infections that compared mortality rates depending on whether patients received active empiric antibiotics.

RESULTS

We found 27 studies of 12 522 patients that reported adjusted OR of active empiric antibiotics on mortality. The pooled adjusted OR was 0.40 (95% CI, 0.32-0.50), favouring active empiric antibiotics. In practice, the mortality effect of empiric antibiotics against P. aeruginosa depends on the prevalence of P. aeruginosa and baseline mortality. The estimated absolute mortality benefit was 0.02% (95% CI, 0.02-0.02) for soft tissue infections, 0.12% (95% CI, 0.10-0.13) for urinary tract infections and community-acquired pneumonia, 0.3% (0.25-0.34) for sepsis without shock, 1.1% (95% CI, 0.9-1.4) for septic shock and 2.4% (95% CI, 1.9-2.8) for nosocomial pneumonia.

CONCLUSIONS

The mortality effect for empiric antibiotics against P. aeruginosa depends crucially on the prevalence of P. aeruginosa and baseline mortality by type of infection. For soft tissue infections, urinary tract infections and community-acquired pneumonia, the mortality benefit is low. Meaningful benefit of empiric antibiotics against P. aeruginosa is limited to patients with approximately 30% mortality and 5% prevalence of P. aeruginosa, which is largely limited to patients in intensive care settings.

Impact of adequate empirical combination therapy on mortality in septic shock due to Pseudomonas aeruginosa bloodstream infections: a multicentre retrospective cohort study

OBJECTIVES

To determine the association of adequate empirical combination therapy (AECT) with 30-day all-cause mortality in patients with septic shock due to Pseudomonas aeruginosa bloodstream infections (BSI).

METHODS

This multicentre, retrospective cohort study analysed data from 14 public hospitals in Italy, including all consecutive adult patients admitted during 2021-2022 with septic shock due to P. aeruginosa BSI. We compared the outcomes of patients receiving AECT to those on adequate empirical monotherapy (AEMT) using Cox regression analyses.

RESULTS

Of the 98 patients who received adequate empirical antibiotic treatment for septic shock due to P. aeruginosa BSI, 24 underwent AECT and 74 were given AEMT. AECT was associated with a lower 30-day all-cause mortality (25%, six out of 24) compared to AEMT (56.8%, 42 out of 74; P = 0.007). Multivariate Cox regression analysis indicated AECT as the only factor significantly associated with improved survival (aHR 0.30; 95% CI 0.12-0.71; P = 0.006). By contrast, the use of monotherapy or combination therapy in the definitive regimen did not influence mortality (aHR 0.73; 95% CI 0.25-2.14; P = 0.568).

CONCLUSIONS

AECT may be associated with reduced mortality compared to monotherapy in septic shock patients due to P. aeruginosa BSI. However, the administration of definitive adequate monotherapy or combination therapy yields similar outcomes, suggesting that once susceptibility is documented, switching to a single active in vitro drug is safe and feasible. Further studies are recommended to validate these findings.

Antimicrobial Treatment of Pseudomonas aeruginosa Severe Sepsis

Pseudomonas aeruginosa is a pathogen often encountered in a healthcare setting. It has consistently ranked among the most frequent pathogens seen in nosocomial infections, particularly bloodstream and respiratory tract infections. Aside from having intrinsic resistance to many antibiotics, it rapidly acquires resistance to novel agents. Given the high mortality of pseudomonal infections generally, and pseudomonal sepsis particularly, and with the rise of resistant strains, treatment can be very challenging for the clinician. In this paper, we will review the latest evidence for the optimal treatment of P. aeruginosa sepsis caused by susceptible as well as multidrug-resistant strains including the difficult to treat pathogens. We will also discuss the mode of drug infusion, indications for combination therapy, along with the proper dosing and duration of treatment for various conditions with a brief discussion of the use of non-antimicrobial agents.

Hetero-Multivalent Targeted Liposomal Drug Delivery to Treat Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa is the leading nosocomial and community-acquired pathogen causing a plethora of acute and chronic infections. The Centers for Disease Control and Prevention has designated multidrug-resistant isolates of P. aeruginosa as a serious threat. A novel delivery vehicle capable of specifically targeting  P. aeruginosa, and encapsulating antimicrobials, may address the challenges associated with these infections. We have developed hetero-multivalent targeted liposomes functionalized with host cell glycans to increase the delivery of antibiotics to the site of infection. Previously, we have demonstrated that compared with monovalent liposomes, these hetero-multivalent liposomes bind with higher affinity to P. aeruginosa. Here, compared with nontargeted liposomes, we have shown that greater numbers of targeted liposomes are found in the circulation, as well as at the site of P. aeruginosa (PAO1) infection in the thighs of CD-1 mice. No significant difference was found in the uptake of targeted, nontargeted, and PEGylated liposomes by J774.A1 macrophages. Ciprofloxacin-loaded liposomes were formulated and characterized for size, encapsulation, loading, and drug release. In vitro antimicrobial efficacy was assessed using CLSI broth microdilution assays and time-kill kinetics. Lastly, PAO1-inoculated mice treated with ciprofloxacin-loaded, hetero-multivalent targeted liposomes survived longer than mice treated with ciprofloxacin-loaded, monovalent targeted, or nontargeted liposomes and free ciprofloxacin. Thus, liposomes functionalized with host cell glycans target P. aeruginosa resulting in increased retention of the liposomes in the circulation, accumulation at the site of infection, and increased survival time in a mouse surgical site infection model. Consequently, this formulation strategy may improve outcomes in patients infected with P. aeruginosa.

Microbial Resistance to Antibiotics and Effective Antibiotherapy

Currently, the efficacy of antibiotics is severely affected by the emergence of the antimicrobial resistance phenomenon, leading to increased morbidity and mortality worldwide. Multidrug-resistant pathogens are found not only in hospital settings, but also in the community, and are considered one of the biggest public health concerns. The main mechanisms by which bacteria develop resistance to antibiotics include changes in the drug target, prevention of entering the cell, elimination through efflux pumps or inactivation of drugs. A better understanding and prediction of resistance patterns of a pathogen will lead to a better selection of active antibiotics for the treatment of multidrug-resistant 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).

Beta-lactam monotherapy or combination therapy for bloodstream infections or pneumonia due to P. aeruginosa: a meta-analysis

OBJECTIVES

. The aim of the present meta-analysis was to compare the clinical and microbiological outcomes of patients treated with beta-lactam monotherapy or combination therapy for Pseudomonas aeruginosa infections.

DATA SOURCES

MEDLINE, Google Scholar and the Cochrane Library STUDY ELIGIBILITY CRITERIA AND INTERVENTIONS: . Experimental and observational studies published as full papers up to December 2020 that compared the efficacy of beta-lactams used in monotherapy or in combination with other active agents as empirical or targeted therapy for bloodstream infections or Hospital-Acquired or Ventilator-Associated Pneumonia (HAP/VAP) due to P. aeruginosa. The outcomes evaluated were hospital-mortality, 14-day- or 30-day-mortality rate, microbiological eradication rate and clinical cure rate.

RESULTS

. Of a total of 8,363 citations screened, 6 Randomized Controlled Trials (RCTs), 6 prospective cohort studies, and 21 retrospective cohort studies were included in the analysis, accounting for a total of 3,861 subjects. Considering the 14 studies evaluating the empirical therapy, no significant difference in mortality rate was observed between the two groups (RR: 1.06; 95% CI 0.86-1.30, p=0.6). Similar findings were obtained among the 18 studies analysing the targeted therapy (RR: 1.04; 95% CI 0.83-1.31, p=0.708); however, grouping the studies according to the design, a higher mortality among patients receiving monotherapy was observed in 5 prospective studies (RR: 1.37; 95% CI 1.06-1.79, p=0.018). Finally, no difference was observed among groups considering the microbiological and the clinical cure.

CONCLUSIONS

. Our meta-analysis demonstrated no difference in the mortality rate, clinical cure and microbiological cure in patients treated with beta-lactam monotherapy or combination for P. aeruginosa infections.

Combination versus monotherapy as definitive treatment for Pseudomonas aeruginosa bacteraemia: a multicentre retrospective observational cohort study

BACKGROUND

Pseudomonas aeruginosa bacteraemia is a common and serious infection. No consensus exists regarding whether definitive combination therapy is superior to monotherapy. We aimed to evaluate the impact of combination therapy on mortality.

METHODS

This was a multicentre retrospective study (nine countries, 25 centres), including 1277 patients with P. aeruginosa bacteraemia during 2009-15. We evaluated the association between β-lactam plus aminoglycoside or quinolone combination therapy versus β-lactam monotherapy and mortality. The primary outcome was 30 day all-cause mortality. Univariate and multivariate Cox regression analyses were conducted, introducing combination as a time-dependent variable. Propensity score was conducted to adjust for confounding for choosing combination therapy over monotherapy.

RESULTS

Of 1119 patients included, 843 received definitive monotherapy and 276 received combination therapy (59% aminoglycoside and 41% quinolone). Mortality at 30 days was 16.9% (189/1119) and was similar between combination (45/276; 16.3%) and monotherapy (144/843; 17.1%) groups (P = 0.765). In multivariate Cox regression, combination therapy was not associated with reduced mortality (HR 0.98, 95% CI 0.64-1.53). No advantage in terms of clinical failure, microbiological failure or recurrent/persistent bacteraemia was demonstrated using combination therapy. Likewise, adverse events and resistance development were similar for the two regimens.

CONCLUSIONS

In this retrospective cohort, no mortality advantage was demonstrated using combination therapy over monotherapy for P. aeruginosa bacteraemia. Combination therapy did not improve clinical or microbiological failure rates, nor affect adverse events or resistance development. Our finding of no benefit with combination therapy needs confirmation in well-designed randomized controlled trials.

A Multicenter Observational Study Evaluating Outcomes Associated With Antibiotic Combination Versus Monotherapy in Patients With Septic Shock

Supplemental Digital Content is available in the text.

Objectives:

To explore the association between antibiotic combination therapy and in-hospital mortality in patients with septic shock in two tertiary ICUs in different countries.

Design:

Retrospective observational study.

Setting:

ICUs of two tertiary hospitals, Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia, and Rigshospitalet, Copenhagen, Denmark.

Patients:

Adult patients with antibiotic treatment greater than or equal to 72 hours and vasopressor therapy greater than or equal to 24 hours.

Intervention:

Combination versus mono antibiotic therapy.

Measurements and Main Results:

Combination antibiotic therapy was defined as receiving two or more antibiotics from different classes, started within 12 hours of each other and with an overlapping duration of greater than or equal to 12 hours. Bivariate and multiple logistic regression analysis were performed comparing combination antibiotic therapy versus antibiotic monotherapy on in-hospital mortality. The analysis was adjusted for age, gender, centre, Acute Physiology and Chronic Health Evaluation II score, and chronic health evaluation. In total, 1,667 patients were included with 953 (57%) receiving combination therapy. Patients given combination therapy were older (60 ± 16 vs 56 ± 18), more likely admitted to Rigshospitalet (58% vs 16%), and had a higher Acute Physiology and Chronic Health Evaluation II score (26 ± 8 vs 23 ± 8). Combination therapy was associated with an increased mortality in univariate analysis (odds ratio = 1.33; 95% CI, 1.07–1.66); however, there was no significant association in the adjusted analysis (odds ratio = 0.88; 95% CI, 0.68–1.15).

Conclusions:

In this retrospective study, no association was found between use of combination therapy and in-hospital mortality. The large differences between centers probably reflect local traditions and lack of definitive evidence.

Pseudomonas aeruginosa: a clinical and genomics update

Antimicrobial resistance (AMR) has become a global medical priority that needs urgent resolution. Pseudomonas aeruginosa is a versatile, adaptable bacterial species with widespread environmental occurrence, strong medical relevance, a diverse set of virulence genes and a multitude of intrinsic and possibly acquired antibiotic resistance traits. P. aeruginosa causes a wide variety of infections and has an epidemic-clonal population structure. Several of its dominant global clones have collected a wide variety of resistance genes rendering them multi-drug resistant (MDR) and particularly threatening groups of vulnerable individuals including surgical patients, immunocompromised patients, Caucasians suffering from cystic fibrosis (CF) and more. AMR and MDR especially are particularly problematic in P. aeruginosa significantly complicating successful antibiotic treatment. In addition, antimicrobial susceptibility testing (AST) of P. aeruginosa can be cumbersome due to its slow growth or the massive production of exopolysaccharides and other extracellular compounds. For that reason, phenotypic AST is progressively challenged by genotypic methods using whole genome sequences (WGS) and large-scale phenotype databases as a framework of reference. We here summarize the state of affairs and the quality level of WGS-based AST for P. aeruginosa mostly from clinical origin.

QSAR Models for Active Substances against Pseudomonas aeruginosa Using Disk-Diffusion Test Data

Pseudomonas aeruginosa is a Gram-negative bacillus included among the six “ESKAPE” microbial species with an outstanding ability to “escape” currently used antibiotics and developing new antibiotics against it is of the highest priority. Whereas minimum inhibitory concentration (MIC) values against Pseudomonas aeruginosa have been used previously for QSAR model development, disk diffusion results (inhibition zones) have not been apparently used for this purpose in the literature and we decided to explore their use in this sense. We developed multiple QSAR methods using several machine learning algorithms (support vector classifier, K nearest neighbors, random forest classifier, decision tree classifier, AdaBoost classifier, logistic regression and naïve Bayes classifier). We used four sets of molecular descriptors and fingerprints and three different methods of data balancing, together with the “native” data set. In total, 32 models were built for each set of descriptors or fingerprint and balancing method, of which 28 were selected and stacked to create meta-models. In terms of balanced accuracy, the best performance was provided by KNN, logistic regression and decision tree classifier, but the ensemble method had slightly superior results in nested cross-validation.

Current choices of antibiotic treatment for Pseudomonas aeruginosa infections

PURPOSE OF REVIEW

Pseudomonas aeruginosa is one of the most feared nosocomial pathogens. Treatment of P. aeruginosa infections is challenging because of the limited choices of antibiotics and the emergent resistance of the pathogen. The present review aims at addressing the management of P. aeruginosa infections and highlighting the novel antibiotics that show a future promising role.

RECENT FINDINGS

Novel fluoroquinolones have been recently introduced and show favorable activity. New combinations of β-lactams/β-lactamase inhibitors have been studied in various indications of infections because of P. aeruginosa. Cefiderocol, a new cephalosporin, shows very promising results against P. aeruginosa. Currently, combination therapy is only recommended in limited scenarios. Extended-infusion of β-lactams exhibit clinical benefit. Bacteriophage therapy is a growing field of interest and may have an impactful effect on the treatment of resistant P. aeruginosa.

SUMMARY

Factors that guide clinical decisions for empiric and directed P. aeruginosa therapy include the epidemiology, the patient's risk factors, the site of infection, and the available treatment options. Conventional antipseudomonal antibiotics have been used successfully for a long time, but the increase in worldwide resistance necessitates the need for newer agents. Antimicrobial stewardship is essential to preserve the new drugs and prevent future development of resistance.

Efflux Pump-Driven Antibiotic and Biocide Cross-Resistance in Pseudomonas aeruginosa Isolated from Different Ecological Niches: A Case Study in the Development of Multidrug Resistance in Environmental Hotspots

Pseudomonas aeruginosa is an opportunistic pathogen displaying high intrinsic antimicrobial resistance and the ability to thrive in different ecological environments. In this study, the ability of P. aeruginosa to develop simultaneous resistance to multiple antibiotics and disinfectants in different natural niches were investigated using strains collected from clinical samples, veterinary samples, and wastewater. The correlation between biocide and antimicrobial resistance was determined by employing principal component analysis. Molecular mechanisms linking biocide and antimicrobial resistance were interrogated by determining gene expression using RT-qPCR and identifying a potential genetic determinant for co- and cross-resistance using whole-genome sequencing. A subpopulation of P. aeruginosa isolates belonging to three sequence types was resistant against the common preservative benzalkonium chloride and showed cross-resistance to fluoroquinolones, cephalosporins, aminoglycosides, and multidrug resistance. Of these, the epidemiological high-risk ST235 clone was the most abundant. The overexpression of the MexAB-OprM drug efflux pump resulting from amino acid mutations in regulators MexR, NalC, or NalD was the major contributing factor for cross-resistance that could be reversed by an efflux pump inhibitor. This is the first comparison of antibiotic-biocide cross-resistance in samples isolated from different ecological niches and serves as a confirmation of laboratory-based studies on biocide adapted isolates. The isolates from wastewater had a higher incidence of multidrug resistance and biocide-antibiotic cross-resistance than those from clinical and veterinary settings.

ICEs Are the Main Reservoirs of the Ciprofloxacin-Modifying crpP Gene in Pseudomonas aeruginosa

The ciprofloxacin-modifying crpP gene was recently identified in a plasmid isolated from a Pseudomonas aeruginosa clinical isolate. Homologues of this gene were also identified in Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii. We set out to explore the mobile elements involved in the acquisition and spread of this gene in publicly available and complete genomes of Pseudomonas spp. All Pseudomonas complete genomes were downloaded from NCBI’s Refseq library and were inspected for the presence of the crpP gene. The mobile elements carrying this gene were further characterized. The crpP gene was identified only in P. aeruginosa, in more than half of the complete chromosomes (61.9%, n = 133/215) belonging to 52 sequence types, of which the high-risk clone ST111 was the most frequent. We identified 136 crpP-harboring integrative and conjugative elements (ICEs), with 93.4% belonging to the mating-pair formation G (MPF_G) family. The ICEs were integrated at the end of a tRNA^Lys gene and were all flanked by highly conserved 45-bp direct repeats. The crpP-carrying ICEs contain 26 core genes (2.2% of all 1193 genes found in all the ICEs together), which are present in 99% or more of the crpP-harboring ICEs. The most frequently encoded traits on these ICEs include replication, transcription, intracellular trafficking and cell motility. Our work suggests that ICEs are the main vectors promoting the dissemination of the ciprofloxacin-modifying crpP gene in P. aeruginosa.

Ceftazidime, Carbapenems, or Piperacillin-tazobactam as Single Definitive Therapy for Pseudomonas aeruginosa Bloodstream Infection: A Multisite Retrospective Study

BACKGROUND

The optimal antibiotic regimen for Pseudomonas aeruginosa bacteremia is controversial. Although β-lactam monotherapy is common, data to guide the choice between antibiotics are scarce. We aimed to compare ceftazidime, carbapenems, and piperacillin-tazobactam as definitive monotherapy.

METHODS

A multinational retrospective study (9 countries, 25 centers) including 767 hospitalized patients with P. aeruginosa bacteremia treated with β-lactam monotherapy during 2009-2015. The primary outcome was 30-day all-cause mortality. Univariate and multivariate, including propensity-adjusted, analyses were conducted introducing monotherapy type as an independent variable.

RESULTS

Thirty-day mortality was 37/213 (17.4%), 42/210 (20%), and 55/344 (16%) in the ceftazidime, carbapenem, and piperacillin-tazobactam groups, respectively. Type of monotherapy was not significantly associated with mortality in either univariate, multivariate, or propensity-adjusted analyses (odds ratio [OR], 1.14; 95% confidence interval [CI], 0.52-2.46, for ceftazidime; OR, 1.3; 95% CI, 0.67-2.51, for piperacillin-tazobactam, with carbapenems as reference in propensity adjusted multivariate analysis; 542 patients). No significant difference between antibiotics was demonstrated for clinical failure, microbiological failure, or adverse events. Isolation of P. aeruginosa with new resistance to antipseudomonal drugs was significantly more frequent with carbapenems (36/206 [17.5%]) versus ceftazidime (25/201 [12.4%]) and piperacillin-tazobactam (28/332 [8.4%] (P = .007).

CONCLUSIONS

No significant difference in mortality, clinical, and microbiological outcomes or adverse events was demonstrated between ceftazidime, carbapenems, and piperacillin-tazobactam as definitive treatment of P. aeruginosa bacteremia. Higher rates of resistant P. aeruginosa after patients were treated with carbapenems, along with the general preference for carbapenem-sparing regimens, suggests using ceftazidime or piperacillin-tazobactam for treating susceptible infection.

Mortality associated with carbapenem-susceptible and Verona Integron-encoded Metallo-β-lactamase-positive Pseudomonas aeruginosa bacteremia

Background

Studies on various Gram-negative bacteria suggest that resistance to carbapenem antibiotics is responsible for increased mortality in patients; however, results are not conclusive. We first assessed the 28-day in-hospital all-cause mortality in patients with Verona Integron-encoded Metallo-β-lactamase-positive Pseudomonas aeruginosa (VIM-PA) bacteremia compared to patients with VIM-negative, carbapenem-susceptible P. aeruginosa (CS-PA) bacteremia. Second, we identified determinants for mortality and survival.

Methods

All patients with a positive blood culture with VIM-PA or CS-PA between January 2004 and January 2016 were included. Kaplan-Meier survival curves were constructed, and survivors and non-survivors were compared on relevant clinical parameters using univariate analyses, and multivariable analyses using a Cox-proportional hazard model.

Results

In total, 249 patients were included, of which 58 (23.3%) died. Seventeen out of 40 (42.5%) patients with VIM-PA died, compared to 41 out of 209 (19.6%) patients with CS-PA (difference = 22.9%, P-value = 0.001). Assumed acquisition of the bacterium at the intensive care unit was significantly associated with mortality (HR = 3.32, 95%CI = 1.60–6.87), and having had adequate antibiotic therapy in days 1–14 after the positive blood culture was identified as a determinant for survival (HR = 0.03, 95%CI = 0.01–0.06). VIM-PA vs CS-PA was not identified as an independent risk factor for mortality.

Conclusions

The crude mortality rate was significantly higher in patients with a VIM-PA bacteremia compared to patients with a CS-PA bacteremia; however, when analyzing the data in a multivariable model this difference was non-significant. Awareness of the presence of P. aeruginosa in the hospital environment that may be transmitted to patients and rapid microbiological diagnostics are essential for timely administration of appropriate antibiotics. Acquisition of P. aeruginosa should be prevented, independent of resistance profile.

Rational approach in the management of Pseudomonas aeruginosa infections

PURPOSE OF REVIEW

This review details the management of Pseudomonas aeruginosa infections covering both current and future treatment options that are and may be available for the clinicians.

RECENT FINDINGS

Pseudomonas aeruginosa infections are a great concern in hospital-acquired infections with very limited therapeutic options. The increasing antibiotic resistance has led to a need for different treatment choices that range from the use of new antibiotics to new nonantibiotic alternative agents to kill or disarm the pathogen.

SUMMARY

New molecules such as ceftolozane-tazobactam, ceftazidime-avibactam, and imipenem-relebactam have shown an adequate activity against P. aeruginosa, especially against multidrug resistance strains. Other nonantibiotic alternative treatments, such as antibodies, bacteriocins or phage therapy, have shown promising results, but future clinical studies are needed.

Antipseudomonal monotherapy or combination therapy for older adults with community-onset pneumonia and multidrug-resistant risk factors: a retrospective cohort study

BACKGROUND

Infectious Diseases Society of America guidelines recommend empiric antipseudomonal combination therapy when Pseudomonas is suspected. However, combination antipseudomonal therapy is controversial. This study compares all-cause 30-day mortality in older patients who received antipseudomonal monotherapy (PMT) or antipseudomonal combination therapy (PCT) for the treatment of community-onset pneumonia.

METHODS

This population-based, retrospective cohort study used data from over 150 Veterans Health Administration hospitals. Patients were classified as being at low, medium, or high risk of drug-resistant pathogens. In total, 31,027 patients were assigned to PCT or PMT treatment arms based on antibiotics received in the first 48 hours of hospital admission.

RESULTS

The unadjusted 30-day mortality difference between PCT and PMT was most pronounced in the low-risk group (18% vs 8%), followed by the medium-risk group (24% vs 18%) and then the high-risk group (39% vs 33%). PCT was associated with higher 30-day mortality than PMT overall (adjusted odds ratio [aOR], 1.54; 95% confidence interval [CI], 1.43-1.66) in all 3 risk groups: low (aOR, 1.69; 95% CI, 1.50-1.89), medium (aOR, 1.30; 95% CI, 1.14-1.48), and high (aOR, 1.21; 95% CI, 1.04-1.40).

CONCLUSIONS

Older adults who received combination antipseudomonal therapy for community-onset pneumonia fared worse than those who received monotherapy. Empiric combination antipseudomonal therapy should not be routinely offered to all patients suspected of having pseudomonal pneumonia.

Combination therapy for treatment of Pseudomonas aeruginosa bloodstream infections

Objectives

Management of bloodstream infections (“BSIs”) caused by Pseudomonas aeruginosa remains controversial as data supporting the use of definite combination treatment for severe P. aeruginosa infections remain conflicting. We aimed to determine differences in mortality between patients treated with definite combination therapy and monotherapy in a large 11-year cohort.

Methods

All consecutive patients with P. aeruginosa BSI hospitalized at the University Hospital Basel, Switzerland, a tertiary academic care center, from January 2003 to December 2013 were included. Pertinent clinical data was assessed. Patients with and without definite combination therapy were compared and hazard ratios for death were calculated.

Results

During the study period, 187 patients with P. aeruginosa BSI were identified. Definite combination therapy was administered in 42.8% (80/187) of all patients, of which 76% (61/80) received a combination of a betalactam with an aminoglycoside and 24% (19/80) received a combination of a betalactam with a quinolone. The remaining 57.2% (107/187) were treated with betalactam monotherapy. Median treatment duration was 15 days (interquartile range 12–20 days). Mortality was lower in patients receiving definite combination therapy in univariable and multivariable cox regression analyses (HR 0.26, 95% CI 0.11–0.60, p = 0.002 and HR 0.30, 95% CI 0.13–0.71, p = 0.006, respectively), the latter adjusting for age, neutropenia at diagnosis, PITT bacteremia score, and inadequate empirical treatment.

Conclusions

Combination therapy (i.e. betalactam-aminoglycoside or betalactam-quinolone combinations) may improve survival of P. aeruginosa BSI, independent of potential confounders such as age, neutropenia, PITT bacteremia score, and inadequate empirical treatment.

Influence of empirical double-active combination antimicrobial therapy compared with active monotherapy on mortality in patients with septic shock: a propensity score-adjusted and matched analysis

Objectives

To evaluate the influence on mortality of empirical double-active combination antimicrobial therapy (DACT) compared with active monotherapy (AM) in septic shock patients.

Methods

A retrospective study was performed of monomicrobial septic shock patients admitted to a university centre during 2010-15. A propensity score (PS) was calculated using a logistic regression model taking the assigned therapy as the dependent variable, and used as a covariate in multivariate analysis predicting 7, 15 and 30 day mortality and for matching patients who received DACT or AM. Multivariate models comprising the assigned therapy group and the PS were built for specific patient subgroups.

Results

Five-hundred and seventy-six patients with monomicrobial septic shock who received active empirical antimicrobial therapy were included. Of these, 340 received AM and 236 DACT. No difference in 7, 15 and 30 day all-cause mortality was found between groups either in the PS-adjusted multivariate logistic regression analysis or in the PS-matched cohorts. However, in patients with neutropenia, DACT was independently associated with a better outcome at 15 (OR 0.29, 95% CI 0.09-0.92) and 30 (OR 0.25, 95% CI 0.08-0.79) days, while in patients with Pseudomonas aeruginosa infection DACT was associated with lower 7 (OR 0.12, 95% CI 0.02-0.7) and 30 day (OR 0.26, 95% CI 0.08-0.92) mortality.

Conclusions

All-cause mortality at 7, 15 and 30 days was similar in patients with monomicrobial septic shock receiving empirical double-active combination therapy and active monotherapy. However, a beneficial influence of empirical double-active combination on mortality in patients with neutropenia and those with P. aeruginosa infection is worthy of further study.

Impact of Pseudomonas aeruginosa bacteraemia in a tertiary hospital: Mortality and prognostic factors

BACKGROUND AND OBJECTIVES

Pseudomonas aeruginosa bacteraemia is associated with a very high mortality, conditioned by comorbidity, source, severity of the episode and lack of adequate treatment. The aim of the study is to know the mortality and prognostic factors of bacteraemia by P.aeruginosa in our hospital.

PATIENTS AND METHODS

We conducted a retrospective study of P.aeruginosa bacteraemia detected between 2009 and 2014. Epidemiological, clinical and microbiological characteristics were described. A risk factor analysis for mortality was performed.

RESULTS

We analysed 110 episodes of bacteraemia, which was more frequent in men of advanced age and with a history of hospitalisation, comorbidity and immunosuppression. Most of the bacteraemias were secondary (mainly of respiratory or urinary source) and led to a significant clinical deterioration. The presence of antibiotic resistance was very high, with 27.3% of multiresistant strains. Empirical treatment was adequate in 60.0% and 92.3% for definite treatment. Overall mortality was 37.3% and attributable mortality was 29.1%. The most important prognostic factors were Charlson index ≥3, history of haematologic malignancy, neutropenia and previous use of corticosteroids, source of bacteraemia, Pitt index ≥4, renal insufficiency, adequate definite treatment, empiric treatment with piperacillin/tazobactam in severe episodes and focus control.

CONCLUSION

P.aeruginosa bacteraemia is associated with a very high mortality, possibly more related to previous comorbidity and severity of the episode than to the treatment chosen. However, the main goal in management remains to optimise treatment, including focus control.

Antibiotic selection in the treatment of acute invasive infections by Pseudomonas aeruginosa: Guidelines by the Spanish Society of Chemotherapy

Pseudomonas aeruginosa is characterized by a notable intrinsic resistance to antibiotics, mainly mediated by the expression of inducible chromosomic β-lactamases and the production of constitutive or inducible efflux pumps. Apart from this intrinsic resistance, P. aeruginosa possess an extraordinary ability to develop resistance to nearly all available antimicrobials through selection of mutations. The progressive increase in resistance rates in P. aeruginosa has led to the emergence of strains which, based on their degree of resistance to common antibiotics, have been defined as multidrug resistant, extended-resistant and panresistant strains. These strains are increasingly disseminated worldwide, progressively complicating the treatment of P. aeruginosa infections. In this scenario, the objective of the present guidelines was to review and update published evidence for the treatment of patients with acute, invasive and severe infections caused by P. aeruginosa. To this end, mechanisms of intrinsic resistance, factors favoring development of resistance during antibiotic exposure, prevalence of resistance in Spain, classical and recently appeared new antibiotics active against P. aeruginosa, pharmacodynamic principles predicting efficacy, clinical experience with monotherapy and combination therapy, and principles for antibiotic treatment were reviewed to elaborate recommendations by the panel of experts for empirical and directed treatment of P. aeruginosa invasive infections.

Comparison of mono- and combination antibiotic therapy for the treatment of Pseudomonas aeruginosa bacteraemia: A cumulative meta-analysis of cohort studies

It is currently unknown whether antibiotic monotherapy or combination therapy is a more effective treatment for patients with Pseudomonas aeruginosa bacteraemia. The present study consists of a systematic review and meta-analysis of cohort studies in associated studies. The treatment options of monotherapy and combination therapy have been compared, to determine which is more effective against P. aeruginosa bacteraemia. Several electronic bibliographic databases were systematically searched and clinical studies that compared combination therapy with monotherapy for P. aeruginosa bacteraemia were identified. Dersimonian and Laird's random-effects models were used to generate summary estimates of the effects and to assess their association according to different patient characteristics and research quality standards. A total of 17 studies were selected, 3 of which were prospective while the remaining 14 were retrospective. The studies involved a total of 2,504 patients. Significant differences between combination therapy and monotherapy treatment were not found when the data were combined (odds ratio (OR)=0.81, 95% confidence interval (CI)=0.61–1.08; P=0.035). The results demonstrated strength in a number of stratification and sensitivity analyses. The variables used included study type, treatment quality score and survival rate of subgroup analysis. To conduct cumulative meta-analysis, the number of years and samples were calculated. The OR value and 95% CI were stable and demonstrated good change trend. According to the size of the sample order following accumulation, OR values and 95% CI (0.89, 0.76–1.04) exhibited a narrow range. Neither combination therapy or monotherapy exhibited significant effects on the mortality of patients with P. aeruginosa bacteraemia. Future research is required and should include large, well-designed prospective cohorts, and grouped clinical studies.