Impact of inappropriate empiric antimicrobial therapy on outcome in Pseudomonas aeruginosa bacteraemia: a stratified analysis according to sites of infection

Ceftolozane/tazobactam for the treatment of Pseudomonas aeruginosa infections: A multicenter case series analysis

INTRODUCTION

Pseudomonas aeruginosa displays resistance to several available antibiotics. Infections caused by this pathogen are associated with a high mortality, morbidity, and considerable healthcare resource utilization and costs. This study was aimed at describing the use of ceftolozane/tazobactam (C/T) for the treatment of patients with P. aeruginosa infections.

METHODS

Case series analysis of hospitalized patients treated with C/T for P. aeruginosa infections in five public Portuguese hospitals. Patients presenting with infections caused by this pathogen and receiving C/T for at least 72h during hospitalization were eligible.

RESULTS

Sixty-four hospitalized patients with P. aeruginosa infections treated with C/T were evaluated between December 2016 and July 2019. Most patients were aged between 60 and 79 years (53.9%). Patients presented a total of 68 P. aeruginosa infections, with respiratory infections being the most common (28.1%, 18 out of 64). Most P. aeruginosa strains (85.9%, 55 out of 64) were extensively drug-resistant (XDR). C/T was mostly used as targeted therapy (98.4%, 63 out of 64 patients) and as monotherapy (72.7%, 47 out of 64 patients). Combination therapy was used in 47.4% (9 out of 19) of patients with bacteriemia. Most patients had successful microbiological (79.2%, 42 out of 53) and clinical (78.7%, 48 out of 61) outcomes. All-cause in-hospital mortality rate was 34.4%.

CONCLUSION

The present case series contributes to the body of evidence suggesting that C/T is an effective and safe option for treating P. aeruginosa infections, namely those caused by XDR strains, both when used as mono- or combination therapy.

Multi-drug resistant Pseudomonas aeruginosa: a 2019-2020 single center retrospective case control study

Multi-drug resistance in the post COVID-19 world is a growing concern. The objective of this study was to describe temporal trends and explore independent risk factors for the isolation of multi-drug resistant (MDR) P. aeruginosa.

Methods

This was a retrospective case-control study of patients with P. aeruginosa isolates recovered from January 2019 to December 2020. MDR P. aeruginosa was defined as non-susceptibility to at least one agent in three or more anti-pseudomonal antimicrobial categories.

Results

In total, 258 unique isolates were identified. Prolonged hospitalization (P<0.001), prior antibiotic use (P<0.001), and respiratory sources (P<0.001) were strongly associated with the presence of MDR P. aeruginosa. From 2019 to 2020, there was a decrease in the total number of P. aeruginosa isolates but a significant increase in the proportion of MDR P. aeruginosa isolates (P=0.015).

Conclusions

Over a period that coincided with the COVID-19 pandemic, there was an increased proportion of MDR P. aeruginosa isolates from hospitalized patients. Improved identification of patients at risk for MDR P. aeruginosa could facilitate appropriate empiric antibiotic decisions like dual anti-pseudomonal therapy. The features of the COVID-19 outbreak that had a severe impact on patient care and that may have affected drug resistance in other respiratory pathogens should be explored.

Prevalence of metallo-β-lactamases as a correlate of multidrug resistance among clinical Pseudomonas aeruginosa isolates in Nepal

Pseudomonas aeruginosa is an opportunistic human pathogen that has developed antibiotic resistance (AR) and causes a range of illnesses, including respiratory pneumonia, gastrointestinal infections, keratitis, otitis media and bacteremia in patients with compromised immune system. The production of metallo-β-lactamases (MBLs) is one of the major mechanisms of AR in this bacterium with ensuing infections difficult to treat. The main goal of this study was to provide a quantitative estimate of MBLs producing clinical P. aeruginosa isolates among the Nepalese patients and determine if MBL correlates with multi-drug resistance (MDR). Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline was followed for meta-analysis of relevant literature using PubMed, Research4Life, and Google Scholar. The prevalence of MBLs in P. aeruginosa from clinical samples was determined using R 4.1.2 for data pooled from studies published until 2021. The meta-analysis of a total of 19 studies selected (of 6038 studies for which titles and abstracts were reviewed) revealed the prevalence of MBLs producing P. aeruginosa (MBL-PA) was 14 % (95 % CI: 0.10-0.19) while MDR isolates among P. aeruginosa was 42 % (95 % CI: 0.30-0.55) in Nepal. Combined Disc Test was predominantly used phenotypic method for confirming MBLs phenotypes among the studies. Sputum was the most common specimen from which MBL-PA was recovered. A significant positive correlation was observed between MDR and MBL production in P. aeruginosa. We conclude that MBL producing strains are widespread among the clinical isolates of P. aeruginosa in Nepal and responsible for emerging MDR strains. It is paramount that antibiotics prescription against the bacterium should be monitored closely and alternative therapeutic modalities against MBL-PA explored.

A review of recent advances in the treatment of adults with complicated urinary tract infection

INTRODUCTION

Complicated urinary tract infections (cUTIs) entail diverse clinical conditions that could be managed differently and not necessarily with premature empiric therapy. Since multidrug-resistant organisms (MDROs) are widely spreading worldwide, the possibility of encountering these resistant bacteria is inevitably part of the daily life of physicians who manage cUTIs.

AREAS COVERED

The advances in the management of cUTIs are explored, illustrating: 1) a proposed therapeutical approach to cUTIs within the antimicrobial stewardship context; 2) evidence regarding novel antibiotics targeting MDROs. Evidence research has been performed through MEDLINE/PubMed using appropriate keywords and terms regarding cUTIs published before June 2022.

EXPERT OPINION

Novel antimicrobial drugs are available in the clinicians' armamentarium. Selecting the optimal therapy for suitable patients may be challenging given the multifaceted group of cUTIs. Carbapenems use is widely increasing, the role of old β-lactam/β-lactamase inhibitors is constantly revised, and novel drugs lack real-life studies. Understanding the different ranges of the complexity of patients affected by cUTIs may help select the most suitable antibiotic for every single case. More multicentric observational studies targeting cUTIs are needed to elucidate the appropriate drug based on patient characteristics and presentations, providing stronger recommendations for cases encountered in everyday clinical practice.

Treatment Heterogeneity in Pseudomonas aeruginosa Pneumonia

We have previously identified substantial antibiotic treatment heterogeneity, even among organism-specific and site-specific infections with treatment guidelines. Therefore, we sought to quantify the extent of treatment heterogeneity among patients hospitalized with P. aeruginosa pneumonia in the national Veterans Affairs Healthcare System from Jan-2015 to Apr-2018. Daily antibiotic exposures were mapped from three days prior to culture collection until discharge. Heterogeneity was defined as unique patterns of antibiotic treatment (drug and duration) not shared by any other patient. Our study included 5300 patients, of whom 87.5% had unique patterns of antibiotic drug and duration. Among patients receiving any initial antibiotic/s with a change to at least one anti-pseudomonal antibiotic (n = 3530, 66.6%) heterogeneity was 97.2%, while heterogeneity was 91.5% in those changing from any initial antibiotic/s to only anti-pseudomonal antibiotics (n = 576, 10.9%). When assessing heterogeneity of anti-pseudomonal antibiotic classes, irrespective of other antibiotic/s received (n = 4542, 85.7%), 50.5% had unique patterns of antibiotic class and duration, with median time to first change of three days, and a median of two changes. Real-world evidence is needed to inform the development of treatment pathways and antibiotic stewardship initiatives based on clinical outcome data, which is currently lacking in the presence of such treatment heterogeneity.

Effect of Combination Antibiotic Empirical Therapy on Mortality in Neutropenic Cancer Patients with Pseudomonas aeruginosa Pneumonia

To assess the effect of combination antibiotic empirical therapy on 30-day case-fatality rate in neutropenic cancer patients with Pseudomonas aeruginosa (PA) bacteremic pneumonia. This was a multinational, retrospective cohort study of neutropenic onco-hematological patients with PA bloodstream infection (BSI) (2006−2018). The effect of appropriate empirical combination therapy, appropriate monotherapy and inappropriate empirical antibiotic therapy [IEAT] on 30-day case-fatality was assessed only in patients with PA bacteremic pneumonia. Among 1017 PA BSI episodes, pneumonia was the source of BSI in 294 (28.9%). Among those, 52 (17.7%) were caused by a multidrug-resistant (MDR) strain and 68 (23.1%) received IEAT, mainly when the infection was caused by an MDR strain [38/52 (73.1%) vs. 30/242 (12.4%); p < 0.001]. The 30-day case-fatality rate was higher in patients with PA bacteremic pneumonia than in those with PA BSI from other sources (55.1% vs. 31.4%; p < 0.001). IEAT was associated with increased 30-day case-fatality (aHR 1.44 [95%CI 1.01−2.03]; p = 0.042), whereas the use of appropriate combination empirical treatment was independently associated with improved survival (aHR 0.46 [95%CI 0.27−0.78]; p = 0.004). Appropriate empirical monotherapy was not associated with improved overall survival (aHR 1.25 [95%CI 0.76−2.05]; p = 0.39). Combination antibiotic empirical therapy should be administered promptly in febrile neutropenic patients with suspected pneumonia as the source of infection.

Therapeutic Strategies for Emerging Multidrug-Resistant Pseudomonas aeruginosa

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates are frequent causes of serious nosocomial infections that may compromise the selection of antimicrobial therapy. The goal of this review is to summarize recent epidemiologic, microbiologic, and clinical data pertinent to the therapeutic management of patients with infections caused by MDR/XDR-P. aeruginosa. Historically, conventional antipseudomonal β-lactam antibiotics have been used for the empiric treatment of MDR/XDR-P. aeruginosa. Owing to the remarkable capacity of P. aeruginosa to confer resistance via multiple mechanisms, these traditional therapies are often rendered ineffective. To increase the likelihood of administering empiric antipseudomonal therapy with in vitro activity, a second agent from a different antibiotic class is often administered concomitantly with a traditional antipseudomonal β-lactam. However, combination therapy may pose an increased risk of antibiotic toxicity and secondary infection, notably, Clostridioides difficile. Multiple novel agents that demonstrate in vitro activity against MDR-P. aeruginosa (e.g., β-lactam/β-lactamase inhibitor combinations and cefiderocol) have been recently granted US Food and Drug Administration (FDA) approval and are promising additions to the antipseudomonal armamentarium. Even so, comparative clinical data pertaining to these novel agents is sparse, and concerns surrounding the scarcity of antibiotics active against refractory MDR/XDR-P. aeruginosa necessitates continued assessment of alternative therapies. This is particularly important in patients with cystic fibrosis (CF) who may be chronically colonized and suffer from recurrent infections and disease exacerbations due in part to limited efficacious antipseudomonal agents. Bacteriophages represent a promising candidate for combatting recurrent and refractory infections with their ability to target specific host bacteria and circumvent traditional mechanisms of antibiotic resistance seen in MDR/XDR-P. aeruginosa. Future goals for the management of these infections include increased comparator clinical data of novel agents to determine in what scenario certain agents may be preferred over others. Until then, appropriate treatment of these infections requires a thorough evaluation of patient- and infection-specific factors to guide empiric and definitive therapeutic decisions.

Evolution of biofilm-forming pathogenic bacteria in the presence of nanoparticles and antibiotic: adaptation phenomena and cross-resistance

Background

Treatment of bacterial biofilms are difficult and in many cases, expensive. Bacterial biofilms are naturally more resilient to antimicrobial agents than their free-living planktonic counterparts, rendering the community growth harder to control. The present work described the risks of long-term use of an important alternative antimicrobial, silver nanoparticles (NAg), for the first time, on the dominant mode of bacterial growth.

Results

NAg could inhibit the formation as well as eradicating an already grown biofilm of Pseudomonas aeruginosa, a pathogen notorious for its resilience to antibiotics. The biofilm-forming bacterium however, evolved a reduced sensitivity to the nanoparticle. Evidence suggests that survival is linked to the development of persister cells within the population. A similar adaptation was also seen upon prolonged exposures to ionic silver (Ag⁺). The persister population resumed normal growth after subsequent passage in the absence of silver, highlighting the potential risks of recurrent infections with long-term NAg (and Ag⁺) treatments of biofilm growth. The present study further observed a potential silver/antibiotic cross-resistance, whereby NAg (as well as Ag⁺) could not eradicate an already growing gentamicin-resistant P. aeruginosa biofilm. The phenomena is thought to result from the hindered biofilm penetration of the silver species. In contrast, both silver formulations inhibited biofilm formation of the resistant strain, presenting a promising avenue for the control of biofilm-forming antibiotic-resistant bacteria.

Conclusion

The findings signify the importance to study the nanoparticle adaptation phenomena in the biofilm mode of bacterial growth, which are apparently unique to those already reported with the planktonic growth counterparts. This work sets the foundation for future studies in other globally significant bacterial pathogens when present as biofilms. Scientifically based strategies for management of pathogenic growth is necessary, particularly in this era of increasing antibiotic resistance.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01027-8.

Clinical characteristics, appropriateness of empiric antibiotic therapy, and outcome of Pseudomonas aeruginosa bacteremia across multiple community hospitals

There is relatively little contemporary information regarding clinical characteristics of patients with Pseudomonas aeruginosa bacteremia (PAB) in the community hospital setting. This was a retrospective, observational cohort study examining the clinical characteristics of patients with PAB across several community hospitals in the USA with a focus on the appropriateness of initial empirical therapy and impact on patient outcomes. Cases of PAB occurring between 2016 and 2019 were pulled from 8 community medical centers. Patients were classified as having either positive or negative outcome at hospital discharge. Several variables including receipt of active empiric therapy (AET) and the time to receiving AET were collected. Variables with a p value of < 0.05 in univariate analyses were included in a multivariable logistic regression model. Two hundred and eleven episodes of PAB were included in the analysis. AET was given to 81.5% of patients and there was no difference in regard to outcome (p = 0.62). There was no difference in the median time to AET in patients with a positive or negative outcome (p = 0.53). After controlling for other variables, age, Pitt bacteremia score ≥ 4, and septic shock were independently associated with a negative outcome. A high proportion of patients received timely, active antimicrobial therapy for PAB and time to AET did not have a significant impact on patient outcome.

Impact of the Sensitivity to Empiric Antibiotics on Clinical Outcomes after Biliary Drainage for Acute Cholangitis

Background/Aims

Empiric antibiotics are given in combination with biliary drainage for acute cholangitis but sometimes turn out to be insensitive to microorganisms in blood and bile. Clinical outcomes were compared according to sensitivity to microorganisms detected in blood and bile culture to evaluate the impact of sensitivity to empiric antibiotics in cholangitis.

Methods

Consecutive patients who underwent biliary drainage for acute cholangitis were retrospectively studied. Clinical outcomes such as 30-day mortality, length of hospital stay and high care unit stay, organ dysfunction and duration of fever were compared in three groups: group A (sensitive to both blood and bile culture), group B (sensitive to blood culture alone) and group C (insensitive to both blood and bile culture).

Results

Eighty episodes of cholangitis were classified according to sensitivity results: 42, 32 and six in groups A, B and C. Escherichia coli and Klebsiella were two major pathogens. There were no significant differences in 30-day mortality rate (7%, 0%, and 0%, p=0.244), length of hospital stay (28.5, 21.0, and 20.5 days, p=0.369), organ dysfunction rate (14%, 25%, and 17%, p=0.500), duration of fever (4.3, 3.2, and 3.5 days, p=0.921) and length of high care unit stay (1.4, 1.2, and 1.7 days, p=0.070) in groups A, B and C. Empiric antibiotics were changed in 11 episodes but clinical outcomes appeared to be non-inferior even in 31 episodes of cholangitis who were on inadequate antibiotics throughout the course.

Conclusions

Sensitivity of empiric antibiotics was not associated with clinical outcomes in acute cholangitis.

An evaluation of antipseudomonal dosing on the incidence of treatment failure

Introduction

Significant mortality is associated with delays in appropriate antibiotic therapy in Pseudomonas aeruginosa infections. The impact of empiric dosing on clinical outcomes has been largely unreported.

Methods

This retrospective cohort compared treatment failure in patients receiving guideline-concordant or guideline-discordant empiric therapy with cefepime, meropenem, or piperacillin/tazobactam. Patients with culture-positive P. aeruginosa between 1 July 2013 and 31 July 2019 were eligible for inclusion. Patients with cystic fibrosis, polymicrobial infection, and urinary or pulmonary colonization were excluded. The composite primary outcome was treatment failure, defined as (1) therapy modification due to resistance/perceived treatment failure, (2) increased/unchanged qSOFA, or (3) persistent fever 48 h after initiating appropriate therapy. Secondary outcomes included rate of infectious diseases consultation, all-cause inpatient mortality, mechanical ventilation requirement, and infection-related intensive care unit and hospital lengths of stay.

Results

In total, 198 patients were included: 90 guideline-concordant and 108 guideline-discordant. Baseline characteristics were balanced. Treatment failure was more common in the guideline-discordant than the guideline-concordant group (62% versus 48%; p = 0.04). This remained significant when adjusting for supratherapeutic dosing (p = 0.02). Infectious diseases consultation was higher in the guideline-discordant group (46% versus 29%, p = 0.01), while intensive care unit length of stay was longer in the guideline-concordant group (4.5 versus 3 days, p = 0.03). Additional secondary outcomes were similar.

Conclusion

Treatment failure was significantly higher in patients receiving guideline-discordant empiric antipseudomonal dosing. Guideline-directed dosing, disease states, and patient-specific factors should be assessed when considering empiric antipseudomonal dosing.

High mortality by nosocomial infections caused by carbapenem-resistant P. aeruginosa in a referral hospital in Brazil: facing the perfect storm

Introduction. Carbapenem-resistant Pseudomonas aeruginosa is responsible for increased patient mortality.Gap Statement. Five and 30 day in-hospital all-cause mortality in patients with P. aeruginosa infections were assessed, followed by evaluations concerning potential correlations between the type III secretion system (TTSS) genotype and the production of metallo-β-lactamase (MBL).Methodology. This assessment comprised a retrospective cohort study including consecutive patients with carbapenem-resistant infections hospitalized in Brazil from January 2009 to June 2019. PCR analyses were performed to determine the presence of TTSS-encoding genes and MBL genes.Results. The 30-day and 5-day mortality rates for 262 patients were 36.6 and 17.9 %, respectively. The unadjusted survival probabilities for up to 5 days were 70.55 % for patients presenting exoU-positive isolates and 86 % for those presenting exo-negative isolates. The use of urinary catheters, as well as the presence of comorbidity conditions, secondary bacteremia related to the respiratory tract, were independently associated with death at 5 and 30 days. The exoS gene was detected in 64.8 % of the isolates, the presence of the exoT and exoY genes varied and exoU genes occurred in 19.3 % of the isolates. The exoU genotype was significantly more frequent among multiresistant strains. MBL genes were not detected in 92 % of the isolates.Conclusions. Inappropriate therapy is a crucial factor regarding the worse prognosis among patients with infections caused by multiresistant P. aeruginosa, especially those who died within 5 days of diagnosis, regardless of the genotype associated with TTSS virulence.

Systematic review of the impact of appropriate versus inappropriate initial antibiotic therapy on outcomes of patients with severe bacterial infections

We investigated the impact of appropriate versus inappropriate initial antimicrobial therapy on the clinical outcomes of patients with severe bacterial infections as part of a systematic review and meta-analyses assessing the impact of delay in appropriate antimicrobial therapy. Literature searches of MEDLINE and Embase, conducted on 24 July 2018, identified studies published after 2007 reporting the impact of delay in appropriate antibiotic therapy for hospitalised adult patients with bacterial infections. Results were statistically pooled for outcomes including mortality, hospital length of stay (LOS) and treatment failure. Subgroup analyses were explored by site of infection where data permitted. Inclusion criteria were met by 145 studies, of which 114 reported data on the impact of appropriate versus inappropriate initial therapy. In the pooled analysis, rates of mortality were significantly in favour of appropriate therapy [odds ratio (OR) = 0.44, 95% CI 0.38-0.50]. Across eight studies, LOS was shorter with appropriate therapy compared with inappropriate therapy [mean difference (MD) -2.54 days (95% CI -5.30 to 0.23)], but not significantly so. The incidence of treatment failure was significantly lower in patients who received appropriate therapy compared with patients who received inappropriate therapy (six studies: OR = 0.33, 95% CI 0.16-0.66) as was mean hospital costs (four studies: MD -7.38 thousand US$ or Euros, 95% CI -14.14 to -0.62). Initiation of appropriate versus inappropriate antibiotics can reduce mortality, reduce treatment failure and decrease LOS, highlighting the importance of broad‑spectrum empirical therapy and rapid diagnostics for early identification of the causative pathogen. [Study registration: PROSPERO: CRD42018104669].

Systematic Review and Meta-Analysis of the Efficacy of Appropriate Empiric Anti-Enterococcal Therapy for Intra-Abdominal Infection

Background: Delayed treatment of seriously infected patients results in increased mortality. However, antimicrobial therapy for the initial 24 to 48 hours is mostly empirically provided, without evidence regarding the causative pathogen. Whether empiric anti-enterococcal therapy should be administered to treat intra-abdominal infection (IAI) before obtaining culture results remains unknown. We performed a meta-analysis to explore the effects of empiric enterococci covered antibiotic therapy in IAI and the risk factors for enterococcal infection in IAI. Methods: We searched multiple databases systematically and included 23 randomized controlled trials (RCTs) and 13 observational studies. The quality of included studies was assessed, and the reporting bias was evaluated. Meta-analysis was performed using random effects or fixed effects models according to the heterogeneity. The risk ratio (RR), odds ratio (OR), and 95% confidence interval (CI) were calculated. Results: Enterococci-covered antibiotic regimens provided no improvement in treatment success compared with control regimens (RR, 0.99; 95% CI, 0.97-1.00; p = 0.15), with similar mortality and adverse effects in both arms. Basic characteristic analysis revealed that most of the enrolled patients with IAI in RCTs were young, lower risk community-acquired intra-abdominal infection (CA-IAI) patients with a relatively low APACHE II score. Interestingly, risk factor screening revealed that malignancy, corticosteroid use, operation, any antibiotic treatment, admission to intensive care unit (ICU), and indwelling urinary catheter could predispose the patients with IAI to a substantially higher risk of enterococcal infection. "Hospital acquired" itself was a risk factor (OR, 2.81; 95% CI, 2.34-3.39; p < 0.001). Conclusion: It is unnecessary to use additional agents empirically to specifically provide anti-enterococcal coverage for the management of CA-IAI in lower risk patients without evidence of causative pathogen, and risk factors can increase the risk of enterococcal infection. Thus, there is a rationale for providing empiric anti-enterococcal coverage for severely ill patients with CA-IAI with high risk factors and patients with hospital-acquired intra-abdominal infection (HA-IAI).

Community-onset Pseudomonas aeruginosa urinary sepsis in elderly people: Predictive factors, adequacy of empirical therapy and outcomes

Purpose To know the predictive factors for Pseudomonas aeruginosa (PA) urinary sepsis in hospitalised elderly patients coming from community, the adequacy of empirical antibiotic therapy and its outcomes. Methods Retrospective case-control study conducted between 2007 and 2017. Patients aged 65 years or older with PA urinary sepsis were included as cases. Three age-matched controls, with urinary sepsis caused by other microorganisms, were selected for each case. Predictors for PA urinary sepsis were determined by logistic regression analysis. Adequacy of empirical antibiotic therapy and outcomes were compared between both groups. Results A total of 332 patients, from which 83 were cases, were included. Predictive factors for PA urinary sepsis were as follows: male sex (OR 3.16, 95% CI 1.61-6.10; P < .001), urinary catheter (OR 3.25, 95% CI 1.73-6.11; P < .001) and healthcare-associated infection (OR 5.52, 95% CI 1.76 -17.29; P = .003). Inadequate empirical antimicrobial therapy (IEAT) and length of hospital stay were higher in PA group (42% vs 24%, P = .002; 7.45 ± 4.36 days vs 6.43 ± 3.82 days, P = .045, respectively), but mortality was not different (7.2% vs 8.8%, P = .648). Conclusions Pseudomonas aeruginosa urinary sepsis in elderly people was associated with male sex, urinary catheter and healthcare-associated infection. These infections had a higher rate of IEAT and a longer hospital stay than urinary sepsis caused by other microorganisms.

Ceftolozane/tazobactam for the treatment of complicated intra-abdominal and urinary tract infections: current perspectives and place in therapy

The current prevalence of infections caused by multidrug-resistant (MDR) organisms is a global threat, and thus, the development of new antimicrobial agents with activity against these pathogens is a healthcare priority. Ceftolozane-tazobactam (C/T) is a new combination of a cephalosporin with a β-lactamase inhibitor that shows excellent in vitro activity against a broad spectrum of Enterobacteriaceae and Pseudomonas aeruginosa, including extended spectrum β-lactamase-producing (ESBL) strains and MDR or extensively drug-resistant (XDR) P. aeruginosa. In phase III randomized clinical trials, C/T demonstrated similar efficacy to meropenem for the treatment of complicated intra-abdominal infections (cIAIs) and superior efficacy to levofloxacin for the treatment of complicated urinary tract infections (cUTIs), including pyelonephritis. The drug is generally safe and well tolerated and its PK/PD profile is very favorable. Observational studies with C/T have revealed good efficacy for the treatment of different types of infection caused by MDR or XDR P. aeruginosa, including some that originated from the digestive or urinary tracts. The place of C/T in therapy is not well defined, but its use could be recommended in a carbapenem-sparing approach for the treatment of infections caused by ESBL-producing strains or for the treatment of infections caused by P. aeruginosa if there are no other more favorable therapeutic options. Further clinical experience is needed to position this new antimicrobial drug for the empirical treatment of cIAIs or cUTIs.

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.

Evaluation of early antimicrobial therapy adaptation guided by the BetaLACTA® test: a case-control study

Background

Rapid diagnostic tests detecting microbial resistance are needed for limiting the duration of inappropriateness of empirical antimicrobial therapy (EAT) in intensive care unit patients, besides reducing the use of broad-spectrum antibiotics. We hypothesized that the betaLACTA® test (BLT) could lead to early increase in the adequacy of antimicrobial therapy.

Methods

This was a case-control study. Sixty-one patients with BLT-guided adaptation of EAT were prospectively included, and then matched with 61 “controls” having similar infection characteristics (community or hospital-acquired, and source of infection), in whom EAT was conventionally adapted to antibiogram results. Endpoints were to compare the proportion of appropriate (primary endpoint) and optimal (secondary endpoint) antimicrobial therapies with each of the two strategies, once microbiological sample culture results were available.

Results

Characteristics of patients, infections and EAT at inclusion were similar between groups. Nine early escalations of EAT occurred in the BLT-guided adaptation group, reaching 98% appropriateness vs. 77% in the conventional adaptation group (p < 0.01). The BLT reduced the time until escalation of an inappropriate EAT from 50.5 (48–73) to 27 (24–28) hours (p < 0.01). Seventeen early de-escalations occurred in the BLT-guided adaptation group, compared to one in the conventional adaptation group, reducing patients’ exposure to broad-spectrum beta-lactam such as carbapenems. In multivariate analysis, use of the BLT was strongly associated with early appropriate (OR = 18 (3.4–333.8), p = 0.006) and optimal (OR = 35.5 (9.6–231.9), p < 0.001) antimicrobial therapies. Safety parameters were similar between groups.

Conclusions

Our study suggests that a BLT-guided adaptation strategy may allow early beta-lactam adaptation from the first 24 hours following the beginning of sepsis management.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1746-6) contains supplementary material, which is available to authorized users.

Pseudomonas aeruginosa urinary tract infections in hospitalized patients: Mortality and prognostic factors

Background

The aim of this study was to analyze the mortality and predictors of 30-day mortality among hospitalized patients with Pseudomonas aeruginosa urinary tract infection (PAUTI) and the impact of antibiotic treatment on survival.

Methods

Patients admitted to our hospital with PAUTI or those diagnosed of PAUTI during hospitalization for other disease between September 2012 and September 2014 were included. Repeated episodes from the same patient were excluded. Database with demographic, clinical and laboratory ítems was created. Empirical and definitive antibiotic therapy, antimicrobial resistance and all-cause mortality at 30 and 90 days were included.

Results

62 patients were included, with a mean age of 75 years. 51% were male. Mortality was 17.7% at 30 days and 33.9% at 90 days. Factors associated with reduced survival at 30 days were chronic liver disease with portal hypertension (P<0,01), diabetes mellitus (P = 0,04) chronic renal failure (P = 0,02), severe sepsis or septic shock (P<0,01), Charlson index > 3 (P = 0.02) and inadequated definitive antibiotic treatment (P<0,01). Independent risk factors for mortality in multivariate analysis were advanced chronic liver disease (HR 77,4; P<0,01), diabetes mellitus (HR 3,6; P = 0,04), chronic renal failure (HR 4,1; P = 0,03) and inadequated definitive antimicrobial treatment (HR 6,8; P = 0,01).

Conclusions

PAUTI are associated with high mortality in hospitalized patients, which increases significantly in those with severe comorbidity such as chronic renal failure, advanced liver disease or diabetes mellitus. Inadequated antibiotic treatment is associated with poor outcome, which remarks the importance of adjusting empirical antibiotic treatment based on the microbiological susceptibility results.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

Carbapenem-resistant Pseudomonas aeruginosa: association with virulence genes and biofilm formation

Pseudomonas aeruginosa is an opportunistic pathogen that causes frequently nosocomial infections, currently becoming more difficult to treat due to the various resistance mechanisms and different virulence factors. The purpose of this study was to determine the risk factors independently associated with the development of bacteremia by carbapenem-resistant P. aeruginosa, the frequency of virulence genes in metallo-β-lactamases producers and to evaluate their ability to produce biofilm. We conducted a case–control study in the Uberlândia Federal University – Hospital Clinic, Brazil. Polymerase Chain Reaction was performed for metallo-β-lactamases and virulence genes. Adhesion and biofilm assays were done by quantitative tests. Among the 157 strains analyzed, 73.9% were multidrug-resistant, 43.9% were resistant to carbapenems, 16.1% were phenotypically positive for metallo-β-lactamases, and of these, 10.7% were positive for bla_SPM gene and 5.3% positive for bla_VIM. The multivariable analysis showed that mechanical ventilation, enteral/nasogastric tubes, primary bacteremia with unknown focus, and inappropriate therapy were independent risk factors associated with bacteremia. All tested strains were characterized as strongly biofilm producers. A higher mortality was found among patients with bacteremia by carbapenem-resistant P. aeruginosa strains, associated independently with extrinsic risk factors, however it was not evident the association with the presence of virulence and metallo-β-lactamases genes.

Tree-structured survival analysis of patients with Pseudomonas aeruginosa bacteremia: A multicenter observational cohort study

This study aimed to construct a prediction algorithm, which is readily applicable in the clinical setting, to determine the mortality rate for patients with P. aeruginosa bacteremia. A multicenter observational cohort study was performed retrospectively in seven university-affiliated hospitals in Korea from March 2012 to February 2015. In total, 264 adult patients with monomicrobial P. aeruginosa bacteremia were included in the analyses. Among the predictors independently associated with 30-day mortality in the Cox regression model, Pitt bacteremia score >2 and high-risk source of bacteremia were identified as critical nodes in the tree-structured survival analysis. Particularly, the empirical combination therapy was not associated with any survival benefit in the Cox regression model compared to the empirical monotherapy. This study suggests that determining the infection source and evaluating the clinical severity are critical to predict the clinical outcome in patients with P. aeruginosa bacteremia.

Antimicrobial Stewardship—the State of the Art in 2011 Focus on Outcome and Methods

Antimicrobial stewardship programs attempt to optimize prescribing of these drugs to benefit both current and future patients. Recent regulatory and other incentives have led to widespread adoption of such programs. Measurements of the success of these programs have focused primarily on process measures. However, evaluation of outcome measures will be needed to ensure sustainability of these efforts. Outcome efforts to date provide some evidence for improved care of individual patients, some evidence for minimizing emergence of resistance, and ample evidence for cost reduction. Attention to evaluation methods must be increased to provide convincing evidence for the continuation of such programs.

Clinical and economic consequences of hospital-acquired resistant and multidrug-resistant Pseudomonas aeruginosa infections: a systematic review and meta-analysis

Background

Increasing rates of resistant and multidrug-resistant (MDR) P. aeruginosa in hospitalized patients constitute a major public health threat. We present a systematic review of the clinical and economic impact of this resistant pathogen.

Methods

Studies indexed in MEDLINE and Cochrane databases between January 2000-February 2013, and reported all-cause mortality, length of stay, hospital costs, readmission, or recurrence in at least 20 hospitalized patients with laboratory confirmed resistant P. aeruginosa infection were included. We accepted individual study definitions of MDR, and assessed study methodological quality.

Results

The most common definition of MDR was resistance to more than one agent in three or more categories of antibiotics. Twenty-three studies (7,881 patients with susceptible P. aeruginosa, 1,653 with resistant P. aeruginosa, 559 with MDR P. aeruginosa, 387 non-infected patients without P. aeruginosa) were analyzed. A random effects model meta-analysis was feasible for the endpoint of all-cause in-hospital mortality. All-cause mortality was 34% (95% confidence interval (CI) 27% – 41%) in patients with any resistant P. aeruginosa compared to 22% (95% CI 14% – 29%) with susceptible P. aeruginosa. The meta-analysis demonstrated a > 2-fold increased risk of mortality with MDR P. aeruginosa (relative risk (RR) 2.34, 95% CI 1.53 – 3.57) and a 24% increased risk with resistant P. aeruginosa (RR 1.24, 95% CI 1.11 – 1.38), compared to susceptible P. aeruginosa. An adjusted meta-analysis of data from seven studies demonstrated a statistically non-significant increased risk of mortality in patients with any resistant P. aeruginosa (adjusted RR 1.24, 95% CI 0.98 – 1.57). All three studies that reported infection-related mortality found a statistically significantly increased risk in patients with MDR P. aeruginosa compared to those with susceptible P. aeruginosa. Across studies, hospital length of stay (LOS) was higher in patients with resistant and MDR P. aeruginosa infections, compared to susceptible P. aeruginosa and control patients. Limitations included heterogeneity in MDR definition, restriction to nosocomial infections, and potential confounding in analyses.

Conclusions

Hospitalized patients with resistant and MDR P. aeruginosa infections appear to have increased all-cause mortality and LOS. The negative clinical and economic impact of these pathogens warrants in-depth evaluation of optimal infection prevention and stewardship strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/2047-2994-3-32) contains supplementary material, which is available to authorized users.

Frequency of occurrence and antimicrobial susceptibility of Gram-negative bacteremia isolates in patients with urinary tract infection: results from United States and European hospitals (2009-2011)

We evaluated the frequency of occurrence and antimicrobial susceptibility patterns of Gram-negative bacteria isolated from bacteremic patients with UTI from European (EU) and United States (USA) hospitals during a 3-year period (2009-2011). Susceptibility testing was performed by the reference broth microdilution method on 2071 Gram-negative bacilli. The most frequently isolated pathogens were Escherichia coli (63·3/71·3% in USA/EU), Klebsiella spp. (16·7/11·2%) and Proteus mirabilis (6·4/5·0%). Escherichia coli susceptibility rates were generally similar in the USA and EU, with extended-spectrum beta-lactamase (ESBL)-phenotype rates at 8·1% in both regions. Among Klebsiella spp., ESBL rates varied from 11·4/17·1% in 2009 to 16·1/40·4% in 2011 in USA/EU, and susceptibility rates were generally lower in EU compared to the USA. Pseudomonas aeruginosa exhibited lower susceptibility rates to ceftazidime, meropenem and piperacillin/tazobactam in EU (78·4, 78·4 and 76·5%, respectively) compared to USA (91·2, 88·2 and 91·2%, respectively). In summary, very few antimicrobials provided satisfactory coverage (>90%) when tested against Klebsiella spp. and P. aeruginosa isolates in EU.

Time to positivity of blood cultures supports antibiotic de-escalation at 48 hours

BACKGROUND

Appropriate de-escalation of empirical antimicrobial therapy is a fundamental component of antimicrobial stewardship. Concern for the late detection of bloodstream pathogens may undermine early streamlining efforts and subject patients to protracted courses of nonessential therapy.

OBJECTIVE

To quantify the prevalence of bacterial bloodstream infection (BSI) detection after more than 48 hours of culture incubation. We also assessed the impact of antimicrobial therapy delivered prior to blood sample collection.

METHODS

We retrospectively evaluated time to blood culture positivity (TTP) in adult patients at an academic tertiary care hospital. Microbiology reports were reviewed to identify the TTP for the first positive blood culture bottle for each episode of BSI occurring from February 1, 2011, to July 31, 2011. Isolates were classified as true pathogens or contaminants. Blood culture results after 48 hours of incubation were compared with results after 120 hours of incubation.

RESULTS

The median TTP of 416 monomicrobial BSIs and 210 contamination episodes was 13.7 and 24.4 hours, respectively (P < .001). The median TTPs in those who received and did not receive prior antibiotics were 17.0 and 12.8 hours, respectively (P < .001). By 48 hours, 98% of aerobic Gram-positive and Gram-negative BSIs were detected. Culture results at 48 hours were 97% sensitive and had a negative predictive value of 99.8%.

CONCLUSION

Few true BSIs are detected after more than 48 hours of culture incubation. Clinicians may adjust empirical antibiotic coverage at this time with little risk for subsequent bacterial pathogen detection.

Culture-independence for surveillance and epidemiology

Culture-independent methods in microbiology (quantitative PCR (qPCR), sequencing, microarrays, direct from sample matrix assisted laser desorption/ionization time of flight mass spectroscopy (MALDI-TOF MS), etc.) are disruptive technology. Rather than providing the same results as culture-based methods more quickly, more cheaply or with improved accuracy, they reveal an unexpected diversity of microbes and illuminate dark corners of undiagnosed disease. At times, they overturn existing definitions of presumably well-understood infections, generating new requirements for clinical diagnosis, surveillance and epidemiology. However, current diagnostic microbiology, infection control and epidemiology rest principally on culture methods elegantly optimized by clinical laboratorians. The clinical significance is interwoven; the new methods are out of context, difficult to interpret and impossible to act upon. Culture-independent diagnostics and surveillance methods will not be deployed unless the reported results can be used to select specific therapeutics or infection control measures. To cut the knots surrounding the adoption of culture-independent methods in medical microbiology, culture-dependent methods should be supported by consistent culture-independent methods providing the microbial context. This will temper existing biases and motivate appropriate scrutiny of the older methods and results.

Sepsis: a review for the neurohospitalist

Sepsis represents a major challenge in medicine. It begins as a systemic response to infection that can affect virtually any organ system, including the central and peripheral nervous systems. Akin to management of stroke, early recognition and treatment of sepsis are just as crucial to a successful outcome. Sepsis can precipitate myasthenic crisis and lead to encephalopathy and critical illness neuropathy. Stroke and traumatic brain injury can predispose a patient to develop sepsis, whereas Guillain-Barré syndrome is similarly not uncommon following infection. This review article will first describe the essential principles of sepsis recognition, pathophysiology, and management and will then briefly cover the neurologic aspects associated with sepsis. Vigilant awareness of the clinical features of sepsis and timeliness of intervention can help clinicians prevent progression of this disease to a multisystem organ failure, which can be difficult to reverse even after the original source of infection is under control.

Outcomes and risk factors for mortality in community-onset bacteremia caused by extended-spectrum beta-lactamase-producing Escherichia coli, with a special emphasis on antimicrobial therapy

BACKGROUND

Although extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli has emerged as a significant pathogen, there is little information regarding treatment outcomes in community-onset bacteremia due to ESBL E. coli. The purpose of this study was to evaluate treatment outcomes of community-onset bacteremia caused by ESBL-producing E. coli and the factors associated with mortality.

METHODS

A retrospective cohort study was performed, including 92 adult patients with community-onset bacteremia caused by ESBL-producing E. coli.

RESULTS

The 30-day mortality rate was 10.9% (10/92). Independent risk factors for mortality were underlying liver disease and severity of illness (e.g., high Pitt bacteremia score, the presence of severe sepsis or septic shock; p < 0.05). Mortality in patients receiving inappropriate initial antimicrobial therapy was not significantly higher than mortality in those receiving appropriate empirical antimicrobial therapy (10.9 vs 10.7%; p = 0.975), if antimicrobial therapy was adjusted appropriately according to susceptibility results. Carbapenems, piperacillin/tazobactam, fluoroquinolones, and amikacin were the most effective antibiotics for community-onset bacteremia caused by ESBL-producing E. coli, although susceptibility profiles confirmed that alternatives to carbapenems are limited. Of 68 isolates in which the ESBLs and their molecular relationships were studied, all isolates produced ESBLs from the CTX-M family (CTX-M-14, 30 isolates; CTX-M-15, 22; and other CTX-M, 16).

CONCLUSIONS

In patients with community-onset bacteremia caused by ESBL-producing E. coli, severe sepsis and underlying liver disease were significantly associated with mortality, and a delay in appropriate antimicrobial therapy was not associated with a higher mortality if therapy was adjusted appropriately according to the susceptibility results.

Impact of adequate empirical combination therapy on mortality from bacteremic Pseudomonas aeruginosa pneumonia

BACKGROUND

Pseudomonas aeruginosa has gained an increasing amount of attention in the treatment of patients with pneumonia. However, the benefit of empirical combination therapy for pneumonia remains unclear. We evaluated the effects of adequate empirical combination therapy and multidrug-resistance in bacteremic Pseudomonas pneumonia on the mortality.

METHODS

A retrospective cohort study was performed at the 2,700-bed tertiary care university hospital. We reviewed the medical records of patients with bacteremic pneumonia between January 1997 and February 2011. Patients who received either inappropriate or appropriate empirical therapy were compared by using marginal structural model. Furthermore, we investigated the direct impact of combination therapy on clinical outcomes in patients with monomicrobial bacteremic pneumonia.

RESULTS

Among 100 consecutive patients with bacteremic Pseudomonas pneumonia, 65 patients were classified in the adequate empirical therapy group, 32 of whom received monotherapy and 33 combination therapy. In the marginal structural model, only inadequate therapy was significantly associated with 28-day mortality (p = 0.02), and multidrug-resistance was not a significant risk factor.To examine further the direct impact of combination therapy, we performed a subgroup analysis of the 65 patients who received adequate therapy. Multivariate logistic regression analysis identified absence of septic shock at the time of bacteremia (OR, 0.07; 95% CI, 0.01-0.49; p = 0.008), and adequate combination therapy (OR, 0.05; 95% CI, 0.01-0.34; p = 0.002) as variables independently associated with decreased all-cause 28-day mortality.

CONCLUSIONS

Our study suggests that adequate empirical combination therapy can decrease mortality in patients with bacteremic Pseudomonas pneumonia.

Influence of multidrug resistance and appropriate empirical therapy on the 30-day mortality rate of Pseudomonas aeruginosa bacteremia

Infections due to multidrug-resistant (MDR) Pseudomonas aeruginosa are increasing. The aim of our study was to evaluate the influences of appropriate empirical antibiotic therapy and multidrug resistance on mortality in patients with bacteremia due to P. aeruginosa (PAB). Episodes of PAB were prospectively registered from 2000 to 2008. MDR was considered when the strain was resistant to ≥3 antipseudomonal antibiotics. Univariate and multivariate analyses were performed. A total of 709 episodes of PAB were studied. MDR PAB (n = 127 [17.9%]) was more frequently nosocomial and associated with longer hospitalization, bladder catheter use, steroid and antibiotic therapy, receipt of inappropriate empirical antibiotic therapy, and a higher mortality. Factors independently associated with mortality were age (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.002 to 1.033), shock (OR, 6.6; 95% CI, 4 to 10.8), cirrhosis (OR, 3.3; 95% CI, 1.4 to 7.6), intermediate-risk sources (OR, 2.5; 95% CI, 1.4 to 4.3) or high-risk sources (OR, 7.3; 95% CI, 4.1 to 12.9), and inappropriate empirical therapy (OR, 2.1; 95% CI, 1.3 to 3.5). To analyze the interaction between empirical therapy and MDR, a variable combining both was introduced in the multivariate analysis. Inappropriate therapy was significantly associated with higher mortality regardless of the susceptibility pattern, and there was a trend toward higher mortality in patients receiving appropriate therapy for MDR than in those appropriately treated for non-MDR strains (OR, 2.2; 95% CI, 0.9 to 5.4). In 47.9% of MDR PAB episodes, appropriate therapy consisted of monotherapy with amikacin. In conclusion, MDR PAB is associated with a higher mortality than non-MDR PAB. This may be related to a higher rate of inappropriate empirical therapy and probably also to amikacin as frequently the only appropriate empirical therapy given to patients with MDR PAB.