External validation of the INCREMENT-CPE mortality score in a carbapenem-resistant Klebsiella pneumoniae bacteraemia cohort: the prognostic significance of colistin resistance

Validation of the INCREMENT-SOT-CPE score in a large cohort of liver transplant recipients with carbapenem-resistant Enterobacterales infection

BACKGROUND

Management of infections due to carbapenemase-resistant Enterobacterales (CRE) in solid organ transplant (SOT) recipients remains a difficult challenge. The INCREMENT-SOT-CPE score has been specifically developed from SOT recipients to stratify mortality risk, but an external validation is lacking.

METHODS

Multicenter retrospective cohort study of liver transplant (LT) recipients colonized with CRE infection who developed infection after transplant over 7-year period. Primary endpoint was all-cause 30-day mortality from infection onset. A comparison between INCREMENT-SOT-CPE and other selected scores was performed. A two-level mixed effects logistic regression model with random effects for the center was fitted. Performance characteristics at optimal cut-point were calculated. Multivariable Cox regression analysis of risk factors for all-cause 30-day mortality was carried out.

RESULTS

Overall, 250 CRE carriers developed infection after LT and were analyzed. The median age was 55 years (interquartile range [IQR]: 46-62) and 157 were males (62.8%). All-cause 30-day mortality was 35.6%. A sequential organ failure assessment (SOFA) score ≥ 11 showed a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 69.7%, 76.4%, 62.0%, 82.0%, and 74.0%, respectively. An INCREMENT-SOT-CPE ≥ 11 reported a sensitivity, specificity, PPV, NPV, and accuracy of 73.0%, 62.1%, 51.6%, 80.6% and 66.0%, respectively. At multivariable analysis acute renal failure, prolonged mechanical ventilation, INCREMENT-SOT-CPE score ≥ 11 and SOFA score ≥ 11 were independently associated with all-cause 30-day mortality, while a tigecycline-based targeted regimen was found to be protective.

CONCLUSIONS

Both INCREMENT-SOT-CPE ≥ 11 and SOFA ≥ 11 were identified as strong predictors of all-cause 30-day mortality in a large cohort of CRE carriers developing infection after LT.

Inhibition of Enzymatic Acetylation-Mediated Resistance to Plazomicin by Silver Ions

Plazomicin is a recent U.S. Food and Drug Administration (FDA)-approved semisynthetic aminoglycoside. Its structure consists of a sisomicin scaffold modified by adding a 2(S)-hydroxy aminobutyryl group at the N1 position and a hydroxyethyl substituent at the 6' position. These substitutions produced a molecule refractory to most aminoglycoside-modifying enzymes. The main enzyme within this group that recognizes plazomicin as substrate is the aminoglycoside 2'-N-acetyltransferase type Ia [AAC(2')-Ia], which reduces the antibiotic's potency. Designing formulations that combine an antimicrobial with an inhibitor of resistance is a recognized strategy to extend the useful life of existing antibiotics. We have recently found that several metal ions inhibit the enzymatic inactivation of numerous aminoglycosides mediated by the aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib]. In particular, Ag+, which also enhances the effect of aminoglycosides by other mechanisms, is very effective in interfering with AAC(6')-Ib-mediated resistance to amikacin. Here we report that silver acetate is a potent inhibitor of AAC(2')-Ia-mediated acetylation of plazomicin in vitro, and it reduces resistance levels of Escherichia coli carrying aac(2')-Ia. The resistance reversion assays produced equivalent results when the structural gene was expressed under the control of the natural or the blaTEM-1 promoters. The antibiotic effect of plazomicin in combination with silver was bactericidal, and the mix did not show significant toxicity to human embryonic kidney 293 (HEK293) cells.

Current Positioning against Severe Infections Due to Klebsiella pneumoniae in Hospitalized Adults

Infections due to Klebsiella pneumoniae have been increasing in intensive care units (ICUs) in the last decade. Such infections pose a serious problem, especially when antimicrobial resistance is present. We created a task force of experts, including specialists in intensive care medicine, anaesthesia, microbiology and infectious diseases, selected on the basis of their varied experience in the field of nosocomial infections, who conducted a comprehensive review of the recently published literature on the management of carbapenemase-producing Enterobacterales (CPE) infections in the intensive care setting from 2012 to 2022 to summarize the best available treatment. The group established priorities regarding management, based on both the risk of developing infections caused by K. pneumoniae and the risk of poor outcome. Moreover, we reviewed and updated the most important clinical entities and the new antibiotic treatments recently developed. After analysis of the priorities outlined, this group of experts established a series of recommendations and designed a management algorithm.

Extended-spectrum β-lactamase-producing and carbapenem-resistant Enterobacterales bloodstream infection after solid organ transplantation: Recent trends in epidemiology and therapeutic approaches

Background

Infections caused by multidrug‐resistant gram‐negative bacilli (MDR GNB), in particular extended‐spectrum β‐lactamase‐producing (ESBL‐E) and carbapenem‐resistant Enterobacterales (CRE), pose a major threat in solid organ transplantation (SOT). Outcome prediction and therapy are challenging due to the scarcity of randomized clinical trials (RCTs) or well‐designed observational studies focused on this population.

Methods

Narrative review with a focus on the contributions provided by the ongoing multinational INCREMENT‐SOT consortium (ClinicalTrials identifier NCT02852902) in the fields of epidemiology and clinical management.

Results

The Spanish Society of Transplantation (SET), the Group for Study of Infection in Transplantation of the Spanish Society of Infectious Diseases and Clinical Microbiology (GESITRA‐SEIMC), and the Spanish Network for Research in Infectious Diseases (REIPI) recently published their recommendations for the management of MDR GNB infections in SOT recipients. We revisit the SET/GESITRA‐SEIMC/REIPI document taking into consideration new evidence that emerged on the molecular epidemiology, prognostic stratification, and treatment of post‐transplant ESBL‐E and CRE infections. Results derived from the INCREMENT‐SOT consortium may support the therapeutic approach to post‐transplant bloodstream infection (BSI). The initiatives devoted to sparing the use of carbapenems in low‐risk ESBL‐E BSI or to repurposing existing non‐β‐lactam antibiotics for CRE in both non‐transplant and transplant patients are reviewed, as well as the eventual positioning in the specific SOT setting of recently approved antibiotics.

Conclusion

Due to the clinical complexity and relative rarity of ESBL‐E and CRE infections in SOT recipients, multinational cooperative efforts such as the INCREMENT‐SOT Project should be encouraged. In addition, RCTs focused on post‐transplant serious infection remain urgently needed.

Epidemiological, Clinical and Microbiological Characteristics of Patients with Bloodstream Infections Due to Carbapenem-Resistant K. Pneumoniae in Southern Italy: A Multicentre Study

Background: In the present study, our aim was to evaluate the clinical and microbiological characteristics of a cohort of patients with bloodstream infections (BSI) due to Carbapenem-Resistant Enterobacteriaceae (CRE) and investigate the independent predictors of mortality. Methods: All episodes of carbapenem-resistant E. coli (CREc) or K. pneumoniae (CRKp) BSI that were subject to a mandatory notification from January to December 2020 in all acute care hospitals and long-term care facilities of the Campania region in southern Italy were enrolled. All carbapenem-resistant strains were assessed through molecular tests for the presence of five carbapenemase gene families, i.e., K. pneumoniae Carbapenemase (KPC), oxacillinase-48 (OXA-48), New Delhi Metallo-β-lactamase (NDM), Verona integron encoded metallo-β-lactamase (VIM) and Imipenemase (IMP). Results: During the study period, a total of 154 consecutive non-repeated CRE BSI, all due to CRKp, were reported. The most frequently identified genes were KPC in 108 cases (70.1%), followed by metallo-betalactamases (MBL) (16.2%), and OXA-48 (2.6%); in 17 isolates (11%) no carbapenemase was detected. The overall mortality at 90 days was 41.9%. Using a log-rank test, patients without risk factors for CRE infections showed a significantly lower cumulative mortality (p = 0.001). After multivariate logistic regression analysis, the presence of at least one risk factor was the only predictor of mortality (OR: 1.7, 95% CI 1.2–6.1, p = 0.015). Conclusions. The study reported a non-negligible prevalence of MBL-producing organisms among CRKp isolated from blood cultures in our region. This data highlights the importance of molecular characterization of all clinical isolates of carbapenem-resistant organisms.

Association between rectal colonization by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae and mortality: a prospective, observational study

BACKGROUND

We evaluated the association of Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) rectal colonization with crude mortality and whether this association is independent of the risk of KPC-Kp infection..

METHODS

Prospective cohort study of patients followed up 90 days after a study of rectal colonization. Cox-regression was used to study the variables associated with crude mortality. Sensitivity analyses for crude 90-day mortality in different subcohorts were performed.

RESULTS

A total of 1244 patients (1078 non-colonized and 166 colonized) were included. None of the non-colonized patients and 78 (47.0%) of the colonized patients developed KPC-Kp infection. Crude 90-day mortality was 18% (194/1078) in non-colonized patients and 41.6% (69/166) in colonized patients. Rectal colonization was not associated with crude mortality (Hazard Ratio [HR] 1.03; 95% CI 0.69-1.54; p = 0.85) when the model was adjusted for severe KPC-Kp infection (INCREMENT-CPE score [ICS] > 7). KPC-Kp infection with ICS > 7 was associated with an increased risk of all-cause mortality (HR 2.21; 95% CI 1.35-3.63; p = 0.002). In the sensitivity analyses, KPC-Kp colonization was not associated with mortality in any of the analyzed subcohorts, including patients who did not develop KPC-Kp infection (HR 0.93; 95%CI: 0.60-1.43; p=0.74).

CONCLUSIONS

KPC-Kp rectal colonization was not associated with crude mortality. Mortality increased when colonized patients developed severe KPC-Kp infection (ICS > 7). Rectal colonization was a necessary although insufficient condition to die from a KPC-Kp infection.

Activity of the combination of colistin and fosfomycin against NDM-1-producing Escherichia coli with variable levels of susceptibility to colistin and fosfomycin in a murine model of peritonitis

BACKGROUND

Alternative treatments are needed against NDM-1-producing Escherichia coli. Colistin (COL) and fosfomycin (FOS) often remain active in vitro but selection of resistant mutants is frequent if used separately. We determined whether the combination of colistin and fosfomycin may be useful to treat infections with NDM-1-producing E. coli with varying levels of resistance.

METHODS

Isogenic derivatives of E. coli CFT073 with blaNDM-1 and variable levels of resistance to colistin and fosfomycin (CFT073-NDM1, CFT073-NDM1-COL and CFT073-NDM1-FOS, respectively) were used. The combination (colistin + fosfomycin) was tested in vitro and in a fatal peritonitis murine model. Mortality and bacterial loads were determined and resistant mutants detected.

RESULTS

Colistin MICs were 0.5, 16 and 0.5 mg/L and fosfomycin MICs were 1, 1 and 32 mg/L against CFT073-NDM1, CFT073-NDM1-COL and CFT073-NDM1-FOS, respectively. In time-kill curves, combining colistin with fosfomycin was synergistic and bactericidal against CFT073-NDM1 and CFT073-NDM1-FOS, with concentrations of 4× MIC (for both drugs), but not against CFT073-NDM1-COL (concentrations of colistin = 0.5× MIC), due to regrowth with fosfomycin-resistant mutants. Mice died less and bacterial counts were lower in spleen with the combination compared with monotherapy against all strains; the combination prevented selection of resistant mutants except for CFT073-NDM1-COL where fosfomycin-resistant mutants were found in all mice.

CONCLUSIONS

Combining colistin and fosfomycin was beneficial in vitro and in vivo against NDM-1-producing E. coli, even with strains less susceptible to colistin and fosfomycin. However, the combination failed to prevent the emergence of fosfomycin-resistant mutants against colistin-resistant strains. Combining colistin and fosfomycin constitutes an alternative for treatment of NDM-1 E. coli, except against colistin-resistant strains.

Colistin resistance increases 28-day mortality in bloodstream infections due to carbapenem-resistant Klebsiella pneumoniae

Mortality due to K. pneumoniae bacteremia is on rise, particularly in regions with high rates of carbapenem and colistin resistance. We aimed to define risk factors for colistin resistance and its impact on mortality. Patients diagnosed with "carbapenem-resistant K. pneumoniae (CRKp)" bacteremia between 2014 and 2018 were divided into two groups as "colistin susceptible (ColS)" and "colistin resistant (ColR)" based on broth microdilution method. Retrospective case-control study was conducted to compare characteristics and outcomes. Multiple logistic regression model was used to define independent risk factors for acquired colistin resistance and Cox proportional hazard model for 28-day mortality. A total of 82 patients (39 ColS and 43 ColR) were included. Mean age was 61.5 years, and 50 (61%) were male. Colistin resistance was significantly increased with duration of hospital stay (p = 0.007) and prior colistin use (p = 0.007). Overall, the 28-day mortality rate was 66%. Age (p = 0.014) and colistin resistance significantly increased 28-day (p = 0.009) mortality. Microbiological response to treatment within 7 days favors survival. PFGE analysis revealed an outbreak with K. pneumoniae ST78 and ST45 clones. Patients treated with combined antimicrobials had significantly lower 28-day mortality (p = 0.045) in comparison to monotherapy. However, types of combinations did not show significant superiority on each other. Colistin resistance increases 28-day mortality in CRKp bacteremia. Although combined regimens are more effective than monotherapy, existing antibacterial combinations have no apparent superiority to each other. New treatment options are pivotal.

Guía de práctica clínica para la tamización de pacientes con riesgo de colonización por Enterobacterales productores de carbapenemasas y el manejo de infecciones causadas por estas bacterias

Las infecciones por Enterobacterales productores de carbapenemasas (EPC) han aumentado en los últimos años. Colombia se ha convertido en un país endémico para este grupo de microorganismos y las infecciones que causan tienen un impacto importante en términos de morbilidad y mortalidad. La identificación temprana de los portadores de EPC que ingresan como pacientes a las instituciones de salud es necesaria para implementar medidas de aislamiento y control de infecciones adecuadas que limiten la diseminación de este tipo de microorganismos en los hospitales. Además, el tratamiento de estas infecciones es difícil debido a las limitadas alternativas terapéuticas disponibles y la escasez de estudios que demuestren su efectividad en este escenario. Por lo anterior, el objetivo del presente trabajo es desarrollar una guía de práctica clínica (GPC) para la tamización de pacientes con riesgo de colonización por EPC y para el manejo de pacientes con   infecciones, ya sea sospechadas o confirmadas, causadas por este tipo de bacterias, mediante un proceso de adaptación de GPC basado en la metodología ADAPTE. Con este propósito en mente, se hacen recomendaciones informadas en evidencia para realizar la tamización y oportuna identificación de portadores de EPC admitidos en instituciones hospitalarias, así como para el adecuado manejo farmacológico de las infecciones por EPC en este escenario.

External validation of INCREMENT-CPE score in a retrospective cohort of carbapenemase-producing Klebsiella pneumoniae bloodstream infections in critically ill patients

OBJECTIVES

Our aim was to validate the INCREMENT-CPE score (ICS) in patients hospitalized in the intensive care unit (ICU) with bacteraemia due to carbapenemase-producing Klebsiella pneumoniae (CP-Kp).

METHODS

The study was conducted in the ICU of the University General Hospital of Patras, Greece, during a 10-year period (2010-2019). Patients with monomicrobial bacteraemia due to CP-Kp were included. Primary outcome was 14-day mortality. MICs of meropenem, tigecycline, fosfomycin and ceftazidime/avibactam were determined by Etest, whereas for colistin the broth microdilution method was applied. PCR for bla_KPC, bla_VIM, bla_NDM and bla_OXA genes was used.

RESULTS

Among 384 CP-Kp bacteraemias, most were primary (166, 43.2%) followed by catheter-related (143, 37.2%). Most isolates carried bla_KPC (318, 82.8%). Fourteen-day mortality was 26.3% (101 patients). ICS score was 11.1 ± 4.2. An ICS ≥10 showed a sensitivity of 98.0% and a negative predictive value of 98.7%. The area under the curve of ICS (0.800) was comparable to those of the Pitt bacteraemia score (0.799), the Simplified Acute Physiology Score II (SAPS II) (0.797) and the Sequential Organ Failure Assessment score (SOFA) (0.815).

CONCLUSIONS

ICS showed predictive efficacy similar to that of the SAPS II, SOFA and Pitt bacteraemia scores.

Clinical Observation and Prognostic Analysis of Patients With Klebsiella pneumoniae Bloodstream Infection

Background and purpose

The clinical prognosis of Klebsiella pneumoniae(K. pneumoniae) bloodstream infection is poor, and the prevalence of drug-resistant bacteria makes clinical anti-infective treatment more challenging. This retrospective study evaluated the epidemiological characteristics of patients with K. pneumoniae, the risk factors for drug-resistant bacterial infection and death, and analyzed treatment options.

Methods

Clinical data of 297 patients diagnosed with K. pneumoniae bacteremia between June 2014 and June 2019 were collected.

Results

Intensive care unit hospitalization history, operation history, recent antibiotic use history, mechanical ventilation, and number of days hospitalized before bloodstream infection were found to be independent risk factors for drug-resistant bacterial infection. The risk of death for carbapenem-resistant K. pneumoniae infection was 2.942 times higher than that for carbapenem-sensitive K. pneumoniae infection. For extensively drug-resistant K. pneumoniae bacteremia patients, the mortality rate of combined anti-infective therapy was lower.

Conclusions

Clinicians should pay attention to patients with high-risk drug-resistant bacteria infection and administer timely anti-infection treatment. The findings of this study may provide some suggestions for early identification and standardized treatment of patients with K. pneumoniae bacteremia.