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

Effect of Different Piperacillin-Tazobactam Dosage Regimens on Synergy of the Combination with Tobramycin against Pseudomonas aeruginosa for the Pharmacokinetics of Critically Ill Patients in a Dynamic Infection Model

We evaluated piperacillin-tazobactam and tobramycin regimens against Pseudomonas aeruginosa isolates from critically ill patients. Static-concentration time-kill studies (SCTK) assessed piperacillin-tazobactam and tobramycin monotherapies and combinations against four isolates over 72 h. A 120 h-dynamic in vitro infection model (IVM) investigated isolates Pa1281 (MIC_piperacillin 4 mg/L, MIC_tobramycin 0.5 mg/L) and CR380 (MIC_piperacillin 32 mg/L, MIC_tobramycin 1 mg/L), simulating the pharmacokinetics of: (A) tobramycin 7 mg/kg q24 h (0.5 h-infusions, t_1/2 = 3.1 h); (B) piperacillin 4 g q4 h (0.5 h-infusions, t_1/2 = 1.5 h); (C) piperacillin 24 g/day, continuous infusion; A + B; A + C. Total and less-susceptible bacteria were determined. SCTK demonstrated synergy of the combination for all isolates. In the IVM, regimens A and B provided initial killing, followed by extensive regrowth by 72 h for both isolates. C provided >4 log₁₀ CFU/mL killing, followed by regrowth close to initial inoculum by 96 h for Pa1281, and suppressed growth to <4 log₁₀ CFU/mL for CR380. A and A + B initially suppressed counts of both isolates to <1 log₁₀ CFU/mL, before regrowth to control or starting inoculum and resistance emergence by 72 h. Overall, the combination including intermittent piperacillin-tazobactam did not provide a benefit over tobramycin monotherapy. A + C, the combination regimen with continuous infusion of piperacillin-tazobactam, provided synergistic killing (counts <1 log₁₀ CFU/mL) of Pa1281 and CR380, and suppressed regrowth to <2 and <4 log₁₀ CFU/mL, respectively, and resistance emergence over 120 h. The shape of the concentration–time curve was important for synergy of the combination.

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.

A ten-year surveillance of P aeruginosa bloodstream infections in a tertiary care hospital: Trends and risk factors for mortality

BACKGROUND

Pseudomonas aeruginosa (P aeruginosa) is a leading cause of nosocomial bloodstream infections worldwide. This study aimed to evaluate the incidence of P aeruginosa bloodstream infections and to identify predictors of 30-day mortality.

METHODS

A retrospective study was conducted in an academic tertiary hospital in Jordan. The medical records of patients hospitalised over ten years (1 January 2008-31 December 2017) were reviewed to identify patients' positive blood culture of P aeruginosa. Annual incidence, antimicrobial susceptibility patterns and risk factors for 30-day mortality were analysed.

RESULTS

A total of 169 cases of P aeruginosa bloodstream infection were identified, with an overall incidence rate of 0.23 case/1000 admission. The overall crude 30-day mortality was 36.7%. Receipt of corticosteroids (OR = 4.5; P = .0017), severe sepsis and septic shock (OR = 2.7; P = .0476), admission to intensive care unit (OR = 5.9; P = .0004), end-stage renal disease (OR = 4.1; P = .0123), inappropriate empirical therapy (OR = 3.2; P = .0143) and inappropriate definitive therapy (OR = 2.9; P = .0110) were identified as independent risk factors for mortality.

CONCLUSION

The annual incidence of P aeruginosa BSIs was fluctuating over ten years period. Several predictors for 30-day mortality in patients with P aeruginosa BSIs were identified, including inappropriate empirical and definitive therapy.

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.

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.

Risk factors and the resistance mechanisms involved in Pseudomonas aeruginosa mutation in critically ill patients

Background

The objective of this study was to determine the main risk factors of Pseudomonas aeruginosa mutation as well as the mechanisms of acquired resistance.

Methods

We conducted a 2-year prospective study in patients who were carriers of a Pseudomonas aeruginosa strain and who had been admitted to a medical/surgical ICU.

Results

Of the 153 patients who were included, 34 had a mutation in their strain. In a multivariate analysis, a duration of ventilation > 24 days was a risk factor for mutation (risk ratio 4.29; CI 95% 1.94-9.49) while initial resistance was a protective factor (RR 0.36; CI 95% 0.18-0.71). In a univariate analysis, exposure of P. aeruginosa to ceftazidime was associated with an over-production of AmpC cephalosporinase and exposure to meropenem was associated with impermeability. A segmentation method based on the duration of ventilation (> 24 days), initial resistance, and exposure of strains to ceftazidime made it possible to predict at 83% the occurrence of mutation.

Conclusion

The duration of ventilation and the presence of resistance as soon as P. aeruginosa is identified are predictive factors of mutation in ICU patients.

Mortality dynamics of Pseudomonas aeruginosa bloodstream infections and the influence of defective OprD on mortality: prospective observational study

Background

To assess the mortality dynamics of patients with Pseudomonas aeruginosa bloodstream infections (BSIs) and the influence of OprD deficiencies of the microorganism on early mortality.

Methods

A prospective multicentre observational study was conducted with 120 patients with P. aeruginosa BSIs occurring between May 2016 and April 2017 in six general hospitals in South Korea. PCR and sequencing were carried out to identify the alterations in oprD and the presence of virulence factors. Cox regression was used to estimate the risk factors for mortality at each timepoint and Kaplan–Meier survival analyses were performed to determine the mortality dynamics.

Results

During the 6 week follow-up, 10.8% (13/120) of the patients with P. aeruginosa BSIs died in 2 weeks, 14.2% (17/120) in 4 weeks and 20.0% (24/120) in 6 weeks, revealing a steep decrease in cumulative survival between the fourth and sixth weeks. ICU admission and SOFA score were risk factors for mortality in any weeks after BSI onset and causative OprD-defective P. aeruginosa had a risk tendency for mortality within 6 weeks. Among the 120 P. aeruginosa blood isolates, 14 were XDR, nine produced either IMP-6 or VIM-2 MBL, and 21 had OprD deficiency.

Conclusions

BSIs caused by OprD-defective P. aeruginosa resulted in a 2-fold higher 6 week mortality rate (33.3%) than that of BSIs caused by OprD-intact P. aeruginosa (17.2%), likely due to the decreased susceptibility to carbapenems and bacterial persistence in clinical settings.

A retrospective analysis of Pseudomonas aeruginosa bloodstream infections: prevalence, risk factors, and outcome in carbapenem-susceptible and -non-susceptible infections

Background

Pseudomonas aeruginosa (PA) is a leading cause of nosocomial infections, and carbapenem non-susceptible strains are a major threat to patient safety.

Methods

A single center, retrospective comparative analysis of carbapenem-non-susceptible PA (CnSPA) and carbapenem-susceptible PA (CSPA) bloodstream infections (BSIs) was conducted between January 1, 2007, and December 31, 2016. Prevalence and risk factors associated with CnSPA BSIs were examined.

Results

The study enrolled 340 patients with PA BSIs; 30.0% (N = 101) of patients had CnSPA. High APACHE II scores (≥15), central venous catheterization, and delayed application of appropriate definitive therapy were independently associated with higher risk of mortality in PA BSIs. Multivariate analysis revealed that respiratory disease and exposure to carbapenems within the previous 90 days to onset of BSI were independent risk factors for acquisition of CnSPA BSIs. Overall all-cause 30-day mortality associated with PA BSIs was 26.8% (91/340). In addition, mortality was higher in patients with CnSPA than in those with CSPA (37.6% vs. 22.2%, respectively; P = 0.003). Corticosteroid therapy and delayed receipt of effective definitive therapy were independent risk factors for death from CnSPA BSIs.

Conclusion

Increased incidence of CnSPA BSIs was observed during the study period, with higher mortality seen in patients with these infections. Respiratory disease and exposure to carbapenems were independent risk factors for development of CnSPA BSIs. Appropriate definitive therapy reduced mortality rates. BLBLIs were as effective as carbapenems as a treatment for PA BSIs.

Utility of Combination Antimicrobial Therapy in Adults with Bloodstream Infections due to Enterobacteriaceae and Non-Fermenting Gram-Negative Bacilli Based on In Vitro Analysis at Two Community Hospitals

This study examined the utility of combination therapy for bloodstream isolates of Enterobacteriaceae and non-fermenting Gram-negative bacilli (NFGN) from adults at two community hospitals from January 2010 through to June 2015. Changes to in vitro antimicrobial susceptibilities by adding ciprofloxacin or gentamicin to third-generation cephalosporins (3GC) were examined overall and in patients with risk factors for 3GC resistance. Overall ceftriaxone susceptibility among Enterobacteriaceae was 996/1063 (94%) and 247/295 (84%) in patients with 3GC resistance risk factors. Susceptibilities increased marginally by adding ciprofloxacin or gentamicin (mean difference 2.4% (95% CI 1.5, 3.4) and 3.0% (95% CI 2.0, 4.0), respectively, overall and 5.4% (95% CI 2.8, 8.0) and 7.1% (95% CI 4.2, 10.1), respectively, in patients with risk factors). Eighty-three of 105 (79%) NFGN were susceptible to ceftazidime overall and 20/29 (69%) in patients with prior beta-lactam use. Overall mean increase in susceptibilities was 15.2% (95% CI: 8.3, 22.2) and 17.1% (95% CI: 9.8, 24.5) for ciprofloxacin and gentamicin combinations, respectively; and 27.6% (95% CI: 10.3, 44.9) for either one with recent beta-lactam use. In this setting, empirical combination therapy had limited utility for Enterobacteriaceae bloodstream isolates but provided significant additional antimicrobial coverage to ceftazidime for NFGN, particularly in patients with prior beta-lactam use.

A New Scoring System for the Differential Diagnosis between Tuberculous Meningitis and Viral Meningitis

BACKGROUND

Tuberculous meningitis (TBM) is associated with high mortality and morbidity despite administering anti-tuberculous chemotherapy to the patients. Differential diagnosis between TBM and viral meningitis (VM) is difficult in some clinical situations.

METHODS

We reviewed and analyzed records of adult patients who were admitted and diagnosed with TBM or VM at a tertiary hospital in Korea, between January 2006 and December 2015. Diagnostic criteria for TBM were categorized into three groups: definite, probable, and possible TBM. The VM group included patients with no evidence of other meningitis who achieved complete recovery with only conservative treatments. Clinical, laboratory and radiological findings, as well as outcomes, were compared between the TBM and VM groups.

RESULTS

Ninety-eight patients were enrolled. Among the study patients, 47 had TBM and 51 had VM. Based on univariate analysis and multivariate logistic regression, sodium < 135 mmol/L in serum (hyponatremia), lactate dehydrogenase > 70 (U/L) in cerebrospinal fluid (CSF), protein > 160 (mg/dL) in CSF, voiding difficulty, and symptoms of cranial nerve palsy were significant predictive factors for TBM in the final model. We constructed a weighted scoring system with predictive factors from multiple regression analyses. Receiver operating characteristic curve analyses and decision tree analyses were plotted to reveal an optimum cutoff point as 4 with this scoring system (range: 0-13).

CONCLUSION

For differential diagnosis between TBM and VM, we created a new weighted scoring system. This scoring system and decision tree analysis are simple and easy to apply in clinical practice to differentiate TBM from VM.

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.

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.

Combination therapy vs. monotherapy for Gram-negative bloodstream infection: matching by predicted prognosis

The utility of empirical combination antimicrobial therapy for Gram-negative bloodstream infection (BSI) remains unclear. This retrospective, quasi-experimental matched cohort study examined the impact of empirical combination therapy on mortality in patients with Gram-negative BSI. Hospitalized adults with Gram-negative BSI from 1 January 2010 to 31 December 2013 at Palmetto Health Hospitals in Columbia, SC, USA were identified. Patients receiving combination therapy or beta-lactam monotherapy were matched 1:1 based on age, sex and Bloodstream Infection Mortality Risk Score (BSIMRS). Multivariate Cox proportional hazards regression with propensity score adjustment was used to examine overall 28-day mortality and within predefined BSIMRS categories (<5 and ≥5). A total of 380 patients receiving combination therapy or monotherapy for Gram-negative BSI were included in the study. Median age was 66 years and 204 (54%) were female. Overall, 28-day mortality in patients who received combination therapy and monotherapy was 13% and 15%, respectively (P = 0.51). After stratification by BSIMRS, mortality in both combination therapy and monotherapy groups was 1.1% in patients with BSIMRS <5 (P = 0.98) and 27% and 32%, respectively, in patients with BSIMRS ≥5 (P = 0.47). After adjusting for propensity to receive combination therapy, risk of mortality was not significantly different for combination therapy compared to monotherapy (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.51-1.60). This finding persisted for both subgroups of BSIMRS <5 (HR 0.96, 95% CI 0.04-24.28) and BSIMRS ≥5 (HR 0.83, 95% CI 0.46-1.48). There is no survival benefit from empirical combination therapy over monotherapy in patients with Gram-negative BSI, regardless of predicted prognosis at initial presentation.