Gram-Negative Bloodstream Infection: Implications of Antimicrobial Resistance on Clinical Outcomes and Therapy

The epidemiology of gram-negative bacteremia in Lebanon: a study in four hospitals

INTRODUCTION

Gram-negative bacteremia is a life-threatening infection with high morbidity and mortality. Its incidence is rising worldwide, and treatment has become more challenging due to emerging bacterial resistance. Little data is available on the burden and outcome of such infections in Lebanon.

METHODS

We conducted this retrospective study in four Lebanese hospitals. Data on medical conditions and demographics of 2400 patients diagnosed with a bloodstream infection based on a positive blood culture were collected between January 2014 and December 2020.

RESULTS

Most bacteremias were caused by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii, with the more resistant organisms being hospital-acquired. Third-generation cephalosporin and quinolone resistance was steady throughout the study, but carbapenem resistance increased. Mortality with such infections is high, but carbapenem resistance or infection with Pseudomonas or Acinetobacter species were significant risk factors for poor outcomes.

CONCLUSION

This is the first multi-center study from Lebanon on gram-negative bacteremia, resistance patterns, and factors associated with a poor outcome. More surveillance is needed to provide data to guide empirical treatment for bacteremia in Lebanon.

Adult acute leukemia patients with gram-negative bacteria bloodstream infection: Risk factors and outcomes of antibiotic-resistant bacteria

This study aims to analyze the risk factors for the development of multidrug-resistant (MDR) and carbapenem-resistant (CR) bacteria bloodstream infection (BSI) in a patient with acute leukemia (AL) and the mortality in gram-negative bacteria (GNB) BSI. This is a retrospective study conducted at West China Hospital of Sichuan University, which included patients diagnosed with AL and concomitant GNB BSI from 2016 to 2021. A total of 206 patients with GNB BSI in AL were included. The 30-day mortality rate for all patients was 26.2%, with rates of 25.8% for those with MDR GNB BSI and 59.1% for those with CR GNB BSI. Univariate and multivariate analyses revealed that exposure to quinolones (Odds ratio (OR) = 3.111, 95% confidence interval (95%CI): 1.623-5.964, p = 0.001) within the preceding 30 days was an independent risk factor for MDR GNB BSI, while placement of urinary catheter (OR = 6.311, 95%CI: 2.478-16.073, p < 0.001) and exposure to cephalosporins (OR = 2.340, 95%CI: 1.090-5.025, p = 0.029) and carbapenems (OR = 2.558, 95%CI: 1.190-5.497, p = 0.016) within the preceding 30 days were independently associated with CR GNB BSI. Additionally, CR GNB BSI (OR = 2.960, 95% CI: 1.016-8.624, p = 0.047), relapsed/refractory AL (OR = 3.035, 95% CI: 1.265-7.354, p = 0.013), septic shock (OR = 5.108, 95% CI: 1.794-14.547, p = 0.002), platelets < 30 × 109/L before BSI (OR = 7.785, 95% CI: 2.055-29.492, p = 0.003), and inappropriate empiric antibiotic therapy (OR = 3.140, 95% CI: 1.171-8.417, p = 0.023) were independent risk factors for 30-day mortality in AL patients with GNB BSI. Prior antibiotic exposure was a significant factor in the occurrence of MDR GNB BSI and CR GNB BSI. CR GNB BSI increased the risk of mortality in AL patients with GNB BSI.

Antibiotic Therapy Strategies for Treating Gram-Negative Severe Infections in the Critically Ill: A Narrative Review

INTRODUCTION

Not enough data exist to inform the optimal duration and type of antimicrobial therapy against GN infections in critically ill patients.

METHODS

Narrative review based on a literature search through PubMed and Cochrane using the following keywords: "multi-drug resistant (MDR)", "extensively drug resistant (XDR)", "pan-drug-resistant (PDR)", "difficult-to-treat (DTR) Gram-negative infection," "antibiotic duration therapy", "antibiotic combination therapy" "antibiotic monotherapy" "Gram-negative bacteremia", "Gram-negative pneumonia", and "Gram-negative intra-abdominal infection".

RESULTS

Current literature data suggest adopting longer (≥10-14 days) courses of synergistic combination therapy due to the high global prevalence of ESBL-producing (45-50%), MDR (35%), XDR (15-20%), PDR (5.9-6.2%), and carbapenemases (CP)/metallo-β-lactamases (MBL)-producing (12.5-20%) Gram-negative (GN) microorganisms (i.e., Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumanii). On the other hand, shorter courses (≤5-7 days) of monotherapy should be limited to treating infections caused by GN with higher (≥3 antibiotic classes) antibiotic susceptibility. A general approach should be based on (i) third or further generation cephalosporins ± quinolones/aminoglycosides in the case of MDR-GN; (ii) carbapenems ± fosfomycin/aminoglycosides for extended-spectrum β-lactamases (ESBLs); and (iii) the association of old drugs with new expanded-spectrum β-lactamase inhibitors for XDR, PDR, and CP microorganisms. Therapeutic drug monitoring (TDM) in combination with minimum inhibitory concentration (MIC), bactericidal vs. bacteriostatic antibiotics, and the presence of resistance risk predictors (linked to patient, antibiotic, and microorganism) should represent variables affecting the antimicrobial strategies for treating GN infections.

CONCLUSIONS

Despite the strategies of therapy described in the results, clinicians must remember that all treatment decisions are dynamic, requiring frequent reassessments depending on both the clinical and microbiological responses of the patient.

Bacteriological Profile and Antimicrobial Susceptibility Patterns of Gram-Negative Bloodstream Infection and Risk Factors Associated with Mortality and Drug Resistance: A Retrospective Study from Shanxi, China

Objective

The aim of this study was to analyze the epidemiological of gram-negative bloodstream infection (GNBSI) and establish a risk prediction model for mortality and acquiring multidrug resistant (MDR), the extended spectrum beta-lactamases (ESBLs) producing and carbapenem-resistant (CR) GNBSI.

Methods

This retrospective study covered five years from January 2015 to December 2019. Data were obtained from Hospital Information System (HIS) and microbiology department records. The risk factors for mortality and acquiring MDR, ESBLs-producing and CR GNBSI were analyzed by univariable and multivariable analysis.

Results

A total of 1018 GNBSI cases were collected. A majority of GNBSI patients were in hematology ward (23.77%). There were 38.61% patients who were assigned in the 41–60 age group. Escherichia coli was the most common gram-negative organism (49.90%). Among isolates of GNBSI, 40.47% were found to be MDR strains, 34.09% were found to be ESBLs-producing strains and 7.06% were found to be CR strains. Escherichia coli was the most common MDR (71.36%) and ESBLs-producing strain (77.81%). Acinetobacter baumannii was the most common CR isolate (46.15%). Multivariate analysis indicated that diabetes mellitus, solid organ tumor, non-fermentative bacteria, MDR strain, central venous cannula, urinary catheter, therapy with carbapenems or tigecycline prior 30 days of infection were independent mortality risk factors for GNBSIs. Over all, therapy with tigecycline prior 30 days of infection was the mutual predictor for mortality of GNBSI, acquiring MDR, ESBLs-producing and CR GNBSI (OR, 8.221, OR, 3.963, OR, 3.588, OR, 9.222, respectively, all p < 0.001).

Conclusion

Collectively, our study implies that patients who were diagnosed as GNBSI had a younger age. Therapy with tigecycline was the mutual and paramount predictor for mortality of GNBSI, acquiring MDR, ESBLs-producing and CR GNBSI. Our investigation had provided a theoretical basis for the use of antibiotics and prevention and control of hospital infection in our region.