Carbapenemase-producing Klebsiella pneumoniae and hematologic malignancies

Multidrug-resistant ST11-KL64 hypervirulent Klebsiella pneumoniae with multiple bla- genes isolated from children's blood

Introduction

Hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) poses an increasing public health risk due to its high treatment difficulty and associated mortality, especially in bone marrow transplant (BMT) patients. The emergence of strains with multiple resistance mechanisms further complicates the management of these infections.

Methods

We isolated and characterized a novel ST11-KL64 hv-CRKP strain from a pediatric bone marrow transplantation patient. Antimicrobial susceptibility testing was performed to determine resistance patterns. Comprehensive genomic analysis was conducted to identify plasmid types, virulence factors, and antimicrobial resistance genes, as well as potential resistance mechanisms associated with mutations and plasmid-mediated variants.

Results

The isolated hv-CRKP strain exhibited multidrug resistance to carbapenem, tigecycline, and polymyxin. Genomic analysis revealed that the IncHI1B/repB plasmid carried virulence factors (rmpA, ΔrmpA2, iucABCD, iutA), while IncFII/IncR and IncFII plasmids harbored resistance genes [bla C T X - M - 6 5 , bla T E M - 1 B , rmtB, bla S H V - 1 2 , bla K P C - 2 , qnrS1, bla L A P - 2 , sul2, dfrA14, tet(A), tet(R)]. The coexistence of bla C T X - M - 6 5 , bla T E M - 1 B , bla S H V - 1 2 , bla L A P - 2 ,and bla K P C - 2 in one hv-CRKP strain is exceptionally rare. Additionally, the Tet(A)-S251A variant in the conjugative plasmid pTET-4 may confer tigecycline resistance. Mutations in MgrB, PhoPQ, and PmrABCDK were identified as potential contributors to increased polymyxin resistance. Interestingly, plasmid-encoded restriction-modification systems and Retron regions were identified, which could potentially confer phage resistance.

Discussion

The combination of virulence and antimicrobial resistance factors in the ST11-KL64 hv-CRKP strain represents a significant challenge for treating immunocompromised pediatric patients. Particularly concerning is the resistance to polymyxin and tigecycline, which are often last-resort treatments for multidrug-resistant infections. The findings highlight the urgent need for effective surveillance, infection control measures, and novel therapeutic strategies to manage such hypervirulent and multidrug-resistant pathogens.

Clinical characteristics and prognosis of bloodstream infections with carbapenem-resistant Gram-negative organisms in patients with hematological malignancies: A multicenter case-control study in China

OBJECTIVE

To investigate clinical characteristics of hematological malignancy (HM) patients with carbapenem-resistant gram-negative organism (CRO) bloodstream infections (BSI) in China, and to elucidate the prognostic risk factors of CRO BSI.

METHODS

We conducted a multicenter case-control study of 201 HM patients with CRO BSI between 2018-2020. Antimicrobial susceptibility testing and whole genome sequencing were performed for CRO isolates. Independent risk factors for 28-day crude mortality were analyzed using Cox proportional hazards regression models. The subgroups of major species were also evaluated.

RESULTS

The pathogens responsible for CRO BSI in HM patients dominated by ST11 CRKP, ST167 CREC and ST463 CRPA. Most isolates produced carbapenemases with KPC and NDM being the main. CRO isolates had resistance rates to conventional antimicrobials ranging from 55%-100% and poor susceptibility to novel antimicrobials related to carbapenemases and species. The 28-day crude mortality was 24.2%. Non-Hodgkin lymphoma, heart disease, blaKPC-2 positive, empirical antibiotic therapy with linezolid, Pitt bacteremia score >3.5 were risk factors for 28-day mortality and appropriate definitive antibiotic therapy, tigecycline-containing therapy and aminoglycoside-containing therapy were protective factors. blaKPC-2 positive in CRKP and ST463 in CRPA were associated with Pitt bacteremia score >3.5. Solid tumor and other site infections before BSI were risk factors for ST463 CRPA BSI and pulmonary infection before BSI was risk factor for KPC-KP BSI.

CONCLUSIONS

The antimicrobial resistance of CRO isolates for BSI in HM patients is critical. HM patients with CRO BSI should be treated with appropriate definitive antibiotic therapy based on early clarification of pathology and their antimicrobial susceptibility.

Clinical and genomic characterization of carbapenem-resistant Enterobacterales bloodstream infections in patients with hematologic malignancies

Background

Carbapenem-resistant Enterobacterales (CRE) bloodstream infections (BSIs) pose a significant risk to patients with hematologic malignancies, yet the distinct features and outcomes of these infections are not thoroughly understood.

Methods

This retrospective study examined the characteristics and clinical outcomes of patients with Enterobacterales BSIs at the Hematology Department of Fujian Medical University Union Hospital from 2018 to 2022. Whole-genome sequencing was conducted on 45 consecutive CRE BSI isolates during this period.

Results

A total of 301 patients with Enterobacterales BSIs were included, with 65 (21.6%) cases of CRE and 236 (78.4%) cases of carbapenem-susceptible Enterobacterales (CSE). CRE infections accounted for 16.9% to 26.9% of all Enterobacterales BSIs, and carbapenem-resistant Klebsiella pneumoniae (CRKP) was the predominant strain. The most frequent sequence type (ST) and carbapenemase among CRKP were ST11 (68.6%) and blaKPC-2 (80.0%), respectively. Perianal infections, multiple infection foci, and a history of multiple hospitalizations, ICU stays, and prior CRE infections were identified as risk factors for CRE BSIs. Patients in the CRE group experienced significantly higher proportions of infection-related septic shock (43.1% vs. 19.9%, P < 0.0003) and 30-day all-cause mortality (56.9% vs. 24.6%, P < 0.0001) compared to those in the CSE group. Patient's age and disease subtypes, strain subtypes, and antimicrobial treatment regimens significantly influenced survival in patients with CRE BSIs.

Conclusions

CRE BSIs are a frequent complication in patients with hematological malignancies undergoing treatment and are associated with poor survival rates. A comprehensive understanding of risk factors and ongoing surveillance of prevalent strains are essential for the effective management of these infections.

Evaluation of synergism effect of human glucose-dependent insulinotropic polypeptide (GIP) on Klebsiella pneumoniae carbapenemases (KPC) producer isolated from clinical samples

Antibiotic resistance is increasing among Gram-negative bacteria, prompting the development of new antibiotics as well as alternative treatment approaches. Klebsiella pneumoniae Carbapenemases (KPC) has become a major concern in the treatment of infections, since KPC-producing bacteria are resistant to a number of β -lactam and non β-lactam antibiotics in addition to hydrolyzing carbapenemases. The aim of this study is to examine the synergistic effect of human Glucose-dependent Insulinotropic Polypeptide (GIP) on KPC producer. The K. pneumoniae isolates were identified by using biochemical tests and PCR genotyping. The disc diffusion method was used to assess the antimicrobial susceptibility of each isolate, and the modified Hodge test (MHT) was used to find carbapenemases. Agar well diffusion and minimum inhibitory concentration (MIC) assays were used to validate the synergistic effect of GIP against Klebsiella species. MIC values of chosen antimicrobial compounds demonstrated a considerable synergism impact when combined with human GIP, particularly against KPC strains. The antibacterial activity of the antimicrobial compounds was boosted by 4-16 times due to human GIP, reducing the MIC values. The fractional inhibitory concentration (FIC) ranged from 0.032 to 0.25 for examined antibiotics. Thus, GIP can be considered an antibacterial adjuvant with the potential to supplement the current antibiotic spectrum.

Global impact of antibacterial resistance in patients with hematologic malignancies and hematopoietic cell transplant recipients

Patients with hematologic malignancies and hematopoietic cell transplant (HCT) recipients are at high risk of developing bacterial infections. These patients may suffer severe consequences from these infections if they do not receive immediate effective therapies, and thus are uniquely threatened by antimicrobial-resistant bacteria. Here, we outline how the emergence of specific resistant bacteria threatens the effectiveness of established approaches to prevent and treat infections in this population. The emergence of fluoroquinolone resistance among Enterobacterales and viridans group streptococci may decrease the effectiveness of fluoroquinolone prophylaxis during neutropenia. The emergence of Enterobacterales that produce extended-spectrum β-lactamases or carbapenemases and of increasingly resistant Pseudomonas aeruginosa may result in neutropenic patients experiencing delayed time to active antibacterial therapy, and consequently worse clinical outcomes. The ability to select targeted antibacterial therapies after the availability of susceptibility data may be limited in patients infected with metallo-β-lactamase-producing Enterobacterales and difficult-to-treat P. aeruginosa. Vancomycin-resistant enterococci and Stenotrophomonas maltophilia can cause breakthrough infections in patients already being treated with broad-spectrum β-lactam antibiotics. Resistance can also limit the ability to provide oral stepdown antibacterial therapy for patients who could otherwise be discharged from hospitalization. We also outline strategies that have the potential to mitigate the negative impact of antimicrobial resistance, including interventions based on active screening for colonization with resistant bacteria and the use of novel rapid diagnostic assays. Additional research is needed to better understand how these strategies can be leveraged to combat the emerging crisis of antimicrobial resistance in patients with hematologic malignancies and HCT recipients.

Oral colonization by gram-negative bacilli in patients with hematologic malignancies and solid tumors compared with healthy controls

BACKGROUND

Colonization of the oropharynx with gram-negative bacilli (GNB) is considered a negative prognostic factor in immunocompromised individuals. Hemato-oncologic patients represent a high-risk group due to their immunodeficiencies and associated treatments. This study aimed to determine the rates of oral colonization by GNB, associated factors, and clinical outcomes in patients with hematologic malignancies and solid tumors compared with healthy subjects.

METHODS

We conducted a comparative study of hemato-oncologic patients and healthy subjects from August to October 2022. Swabs were taken from the oral cavity; specimens with GNB were identified and tested for antimicrobial susceptibility.

RESULTS

We included 206 participants (103 hemato-oncologic patients and 103 healthy subjects). Hemato-oncologic patients had higher rates of oral colonization by GNB (34% vs. 17%, P = 0.007) and GNB resistant to third-generation cephalosporins (11.6% vs. 0%, P < 0.001) compared to healthy subjects. Klebsiella spp. was the predominant genus in both groups. The factor associated with oral colonization by GNB was a Charlson index ≥ 3, while ≥ 3 dental visits per year were a protective factor. Regarding colonization by resistant GNB in oncology patients, antibiotic therapy and a Charlson index ≥ 5 were identified as associated factors, while better physical functionality (ECOG ≤ 2) was associated with less colonization. Hemato-oncologic patients colonized with GNB had more 30-day infectious complications (30.5% vs. 2.9%, P = 0.0001) than non-colonized patients.

CONCLUSION

Oral colonization by GNB and resistant GNB are prevalent in cancer patients, especially those with higher scores on the severity scales. Infectious complications occurred more frequently in colonized patients. There is a knowledge gap about dental hygiene practices in hemato-oncologic patients colonized by GNB. Our results suggest that patients' hygienic-dietary habits, especially frequent dental visits, are a protective factor against colonization.

Decrease in Mortality from Sepsis: Impact of the Multidisciplinary Program for the Hematologic Patient at Very High Risk

A program for the hematologic patient at very high risk of infections (HAR, from its initials in Spanish) was implemented, based on a multidisciplinary team and six measures intended to reduce the colonization and subsequent sepsis by multidrug-resistant organisms (MDRO). We aimed at evaluating the effectiveness of the HAR program in terms of MDRO infections mainly caused by Klebsiella pneumoniae carbapenemase-producing and multidrug-resistant Pseudomona aeruginosa, and sepsis-related mortality. We established retrospective comparisons between the pre-HAR period (2016-2018) and the post-HAR period (2018-2019), in patients who received a hematopoietic stem cell transplant (HSCT) and/or intensive chemotherapy to treat non-M3 acute myeloid leukemia (CH-AML). We included 262 patients: 176 pre-HAR and 86 post-HAR. MDRO infection was 4.6% at 30 days and 6.1% at 90 days (all the cases during the pre-HAR period). Sepsis-related mortality was 6.5%, considering a median follow-up of 608 days: 6.1% in the HSCT group and 12.4% in the CH-AML group (p = 0.306). Sepsis-related mortality was 8.7% in the pre-HAR period and 0% in the post-HAR period (p = 0.014). The implementation of this multidisciplinary program based in preventive measures and the appropriate use of antibiotics enabled a decrease in sepsis-related mortality in very high-risk hematologic patients.

Glycyrrhetinic acid prevents carbapenem-resistant Klebsiella pneumoniae-induced cell injury by inhibiting mitochondrial dysfunction via Nrf-2 pathway

OBJECTIVES

Due to the abuse of antibiotics, the high reoccurrence of drug-resistance strains, such as carbapenem-resistant Klebsiella pneumoniae (CRKP), deteriorates CRKP-infected pneumonia in the clinic, suggesting it is necessary to find new alternatives. Glycyrrhetinic acid (GA), an active ingredient of Yinhuapinggan granule, has antioxidant & anti-inflammatory capacity. Little, however, is known about the effects of GA on CRKP-induced epithelial injury.

METHODS

In this research, we examined the protective effects of GA against pulmonary epithelium damage caused by CRKP infection and potential molecular mechanisms.

RESULTS

Our results noted GA significantly promoted cell survival and reduced pro-inflammatory cytokines production, during CRKP-induced human pulmonary epithelial cell. Mechanically, GA alleviated mitochondrial-damage-induced apoptosis amid CRKP infection by inhibiting mitochondrial damage. Additionally, we found GA inhibited the expression of pro-apoptotic proteins Cyto-c, the Bax, and Caspase-3 while increasing the expression of anti-apoptotic protein Bcl-2. Further exploration found GA could trigger Nrf-2 expression at both gene and protein levels, activating antioxidative proteins to diminish CRKP-induced oxidative stress.

CONCLUSION

Together, our results demonstrated that GA was a promising candidate to alleviate CRKP-infected lung injury as well as a synergist to treat CRKP infection with antibiotics.

Evaluation of ceftazidime/avibactam for treatment of carbapenemase-producing carbapenem-resistant Enterobacterales with OXA-48 and/or NDM genes with or without combination therapy

Background

Carbapenem-resistant Enterobacterales (CRE) is an urgent public health threat of significant global concern. Few observational studies have evaluated the clinical outcomes for treatment of CRE harbouring OXA-48 or NDM genes with ceftazidime/avibactam. Previous findings showed lower 30 day mortality with ceftazidime/avibactam ranges between 8.3% and 22%.

Method

This single-centre retrospective cohort study included adult patients aged ≥18 years admitted to King Abdulaziz Medical City (KAMC) who had received ceftazidime/avibactam for at least 72 h for infections caused by CRE with genes encoding for carbapenemase production (CP-CRE).

Results

A total of 211 patients, mostly male (57%), having CP-CRE infections treated with ceftazidime/avibactam were included, with an average age of 62 years. More than 50% of patients were critically ill, for which 46% received invasive ventilation and 36% were on inotropes. The most frequent infectious disease was hospital/ventilator-acquired pneumonia with Klebsiella pneumoniae being the most frequent causative pathogen. The majority of isolates harboured OXA-48 (81%), followed by NDM ± OXA-48 (19%). The overall clinical cure and 30 day mortality was 78% and 21% respectively (stratified per gene: 79% and 21.6% for OXA-48 and 75% and 17.5% for NDM ± OXA-48).

Conclusions

This was the largest study that evaluated clinical outcomes associate with CP-CRE harbouring OXA-48 gene infections treated with ceftazidime/avibactam. Clinical cure and 30 day mortality were consistent with those of previous studies. Findings suggested that combination therapy with ceftazidime/avibactam had no direct impact on clinical outcomes for CP-CRE with OXA-48.

Risk Factors for Mortality and Outcomes in Hematological Malignancy Patients with Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections

Background

This study aimed to identify risk factors for mortality and outcomes in hematological malignancy (HM) patients with bloodstream infection (BSI) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP).

Methods

A retrospective study was conducted at a tertiary teaching hospital in Henan Province, China, between January 2018 and December 2021. All BSIs caused by CRKP in hospitalized HM patients were identified. Data on patient demographics, disease, laboratory tests, treatment regimens, outcomes of infection, and the antimicrobial susceptibility of each isolate were collected from medical records.

Results

A total of 129 patients with CRKP BSI were included in the study, and the 28-day mortality rate was 80.6% (104/129). In Cox analysis an absolute neutrophil count < 500 at discharge (hazard ratio [HR] 6.386, 95% confidence interval [CI] 3.074–13.266, p < 0.001), intensive care unit admission (HR 1.834, 95% CI 1.065–3.157, p = 0.029), and higher Pitt bacteremia score (HR 1.185, 95% CI 1.118–1.255, p < 0.001) were independent risk factors associated with 28-day mortality. Survival curve analysis indicated that compared with ceftazidime-avibactam-based therapy, both polymyxin b (HR 8.175, 95% CI 1.099–60.804, p = 0.040) and tigecycline (HR 14.527, 95% CI 2.000–105.541, p =0.008) were associated with a higher risk of mortality.

Conclusion

In HM patients CRKP BSI resulted in high mortality. Intensive care unit admission, higher Pitt bacteremia score, and absolute neutrophil count < 500 at discharge were independently associated with higher mortality. Early initiation of new agents such as ceftazidime-avibactam may improve outcomes.

Bacteremia with Carbapenemase-Producing Enterobacterales in Immunocompromised Patients Colonized with These Bacteria

We aimed to analyze rates and risk factors for carbapenemase-producing Enterobacterales (CPE) bloodstream infection (BSI) in CPE-colonized patients with malignancies or following hematopoietic cell transplantation. We retrospectively collected data on demography, underlying disease, colonizing CPE, treatment, intensive care unit (ICU) hospitalization, CPE-BSI, and mortality in CPE-colonized immunocompromised patients (2014-2020). Two hundred twenty-one patients were colonized with 272 CPE: 254 (93.4%) carried one carbapenemase [KPC (50.4%), NDM (34.6%), OXA-48-like (5.2%), and VIM (3.3%)]; 18 (6.6%) carried two carbapenemases. Twenty-eight (12.7%) patients developed CPE-BSI. Univariate analysis revealed CPE-BSI-associated factors: younger age, carbapenem or aminoglycoside exposure, ICU admission, neutropenia, carrying serine carbapenemase-producing, and specifically KPC-producing bacteria, colonization with several CPE, and detection of several carbapenemases. None of 23 auto-HSCT recipients developed CPE-BSI. In multivariate analysis, ICU hospitalization was significantly associated with CPE-BSI (odds ratio [OR] 2.82, 95% CI 1.10-7.20; p = 0.042); solid tumor diagnosis was protective (OR 0.21, 95% CI 0.05-1.01; p = 0.038). One-year crude mortality was 108/221 (48.8%), including 19/28 (67.9%) and 89/193 (46.1%) in patients with and without CPE-BSI, p = 0.104. To conclude, CPE-BSI is rare in CPE-colonized patients with solid tumors and following auto-HSCT. ICU hospitalization increased CPE-BSI risk. These data can help to guide empirical anti-CPE antibiotic therapy in patients colonized with these bacteria.

Multi-body-site colonization screening cultures for predicting multi-drug resistant Gram-negative and Gram-positive bacteremia in hematological patients

BACKGROUND

To investigate the multi-drug resistant bacteria (MDRB) colonization rate in hematological patients hospitalized for any cause using a multi-body-site surveillance approach, and determine the extent to which this screening strategy helped anticipate MDRB bloodstream infections (BSI).

METHODS

Single-center retrospective observational study including 361 admissions documented in 250 adult patients. Surveillance cultures of nasal, pharyngeal, axillary and rectal specimens (the latter two combined) were performed at admission and subsequently on a weekly basis. Blood culture samples were incubated in an automated continuous monitoring blood culturing instrument (BACTEC FX).

RESULTS

In total, 3463 surveillance cultures were performed (pharyngeal, n = 1201; axillary-rectal, n = 1200; nasal, n = 1062). MDRB colonization was documented in 122 out of 361 (33.7%) admissions corresponding to 86 patients (34.4%). A total of 149 MDRB were isolated from one or more body sites, of which most were Gram-negative bacteria, most frequently non-fermenting (n = 83) followed by Enterobacterales (n = 51). BSI were documented in 102 admissions (28%) involving 87 patients. Overall, the rate of BSI caused by MDRB was significantly higher (p = 0.04) in the presence of colonizing MDRB (16 out of 47 admissions in 14 patients) than in its absence (9 out of 55 admissions in 9 patients). Colonization by any MDRB was independently associated with increased risk of MDRB-BSI (HR, 3.70; 95% CI, 1.38-9.90; p = 0.009).

CONCLUSION

MDRB colonization is a frequent event in hematological patients hospitalized for any reason and is associated with an increased risk of MDRB BSI. The data lend support to the use of MDRB colonization surveillance cultures for predicting the occurrence of MDRB BSI in this cohort.

Reduced mortality from KPC-K.pneumoniae bloodstream infection in high-risk patients with hematological malignancies colonized by KPC-K.pneumoniae

BACKGROUND

KPC-K.pneumoniae bloodstream infection (KPC-KpBSI) mortality rate in patients with hematological malignancies is reported about 60%. The initial treatment active against KPC-K.pneumoniae is crucial for survival and KPC-K.pneumoniae rectal colonization usually precedes KPC-KpBSI. We evaluated the impact on KPC-KpBSI mortality of the preemptive use of antibiotics active against KPC-K.pneumoniae, as opposed to inactive or standard empiric antibiotics, for the empiric treatment of febrile neutropenia episodes in patients with hematological malignancy identified as KPC-K.pneumoniae intestinal carriers.

METHODS

We compared the outcomes of KPC-KpBSIs occurring in high-risk hematological patients known to be colonized with KPC-K.pneumoniae, during two time periods: March2012-December2013 (Period 1, initial approach to KPC-K.pneumoniae spread) and January2017-October2018 (Period 2, full application of the preemptive strategy). The relative importance of the various prognostic factors that could influence death rates were assessed by forward stepwise logistic regression models.

RESULTS

KPC-KpBSI-related mortality in hematological patients identified as KPC-K.pneumoniae carriers dropped from 50% in Period 1 to 6% in Period 2 (p < 0.01), from 58 to 9% in acute myeloid leukemia carriers(p < 0.01). KPC-KpBSIs developed in patients identified as KPC-K.pneumoniae carriers were initially treated with active therapy in 56% and 100% of cases in Period 1 and Period 2, respectively (p < 0.01), in particular with an active antibiotic combination in 39 and 94% of cases, respectively(p < 0.01). The 61% of KPC-KpBSI observed in Period 1 developed during inactive systemic antibiotic treatment (none in Period 2, p < 0.01), fatal in the 73% of cases. Overall, KPC-KpBSI-related mortality was 88% with no initial active treatment, 11.5% with at least one initial active antibiotic (p < 0.01), 9% with initial active combination. Only the initial active treatment resulted independently associated with survival.

CONCLUSIONS

In high-risk hematological patients colonized by KPC-K.pneumoniae, the empiric treatment of febrile neutropenia active against KPC-K.pneumoniae reduced KPC-KpBSI-related mortality to 6% and prevented fatal KPC-KpBSI occurrence during inactive systemic antibiotic treatment.

Gram-Negative Bacteria Bloodstream Infections in Patients with Hematological Malignancies - The Impact of Pathogen Type and Patterns of Antibiotic Resistance: A Retrospective Cohort Study

Background

Enterobacteriaceae (EB) and non-fermentative bacteria (NFB) are the main pathogens responsible for gram-negative bloodstream infections (GN-BSI) in patients with hematological malignancies (HMs). These two pathogen types have heterogeneous resistance mechanisms to antibiotics. However, the impact of pathogen species and pattern of antibiotic resistance on the outcomes of patients with HMs remains unclear.

Methods

We retrospectively collected clinical data of patients with HMs at three comprehensive hospitals in Hunan Province, China, between January 2010 and May 2018. The data analyzed the impact that different species and patterns of antibiotic resistance had on the outcome of patients with HMs.

Results

The majority of the 835 monomicrobial isolates collected from patients with HMs and GN-BSIs were Enterobacteriaceae (75.7%). While detections of MDR pathogens in BSIs as a whole are decreasing, sub-analysis shows that detections of extended spectrum β-lactamase-producing (ESBL) Enterobacteriaceae and carbapenem-resistant pathogens in BISs are rising. Comparing different species, the early mortality rate associated with infections caused by NFB was significantly higher than infections caused by Enterobacteriaceae (22.6% vs 9.7%, p < 0.001). Across different multidrug-resistant (MDR) patterns, ESBL bacteria did not have a significant impact on health outcomes. Carbapenem-resistant bacteria, on the other hand, were observed to significantly affect early mortality rate, such as carbapenem-resistant Klebsiella pneumoniae (36.0% vs 7.6%, P < 0.001) and carbapenem-resistant non-fermentative bacteria (44.7% vs 16.5%, P < 0.001).

Conclusion

Our findings suggest that both species and patterns of antibiotic resistance can affect the early mortality of patients with HMs during BSI.

Tandem fecal microbiota transplantation cycles in an allogeneic hematopoietic stem cell transplant recipient targeting carbapenem-resistant Enterobacteriaceae colonization: a case report and literature review

BACKGROUND

Due to limited antibiotic options, carbapenem-resistant Enterobacteriaceae (CRE) infections are associated with high non-relapse mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Also, intestinal CRE colonization is a risk factor for subsequent CRE infection. Several clinical studies have reported successful fecal microbiota transplantation (FMT) for the gut decontamination of a variety of multidrug-resistant bacteria (MDRB), even in immunosuppressed patients. Similarly, other studies have also indicated that multiple FMTs may increase or lead to successful therapeutic outcomes.

CASE PRESENTATION

We report CRE colonization in an allo-HSCT patient with recurrent CRE infections, and its successful eradication using tandem FMT cycles at 488 days after allo-HSCT. We also performed a comprehensive microbiota analysis. No acute or delayed adverse events (AEs) were observed. The patient remained clinically stable with CRE-negative stool culture at 26-month follow-up. Our analyses also showed some gut microbiota reconstruction. We also reviewed the current literature on decolonization strategies for CRE.

CONCLUSIONS

CRE colonization led to a high no-relapse mortality after allo-HSCT; however, well-established decolonization strategies are currently lacking. The successful decolonization of this patient suggests that multiple FMT cycles may be potential options for CRE decolonization.

Carbapenem-Resistant Enterobacteriaceae-Implications for Treating Acute Leukemias, a Subgroup of Hematological Malignancies

Acute leukemias (AL) are a group of aggressive malignant diseases associated with a high degree of morbidity and mortality. Patients with AL are highly susceptible to infectious diseases due to the disease itself, factors attributed to treatment, and specific individual risk factors. Enterobacteriaceae presence (e.g., Klebsiella pneumonia and Escherichia coli) is a frequent cause of bloodstream infections in AL patients. Carbapenem-resistant Enterobacteriaceae (CRE) is an emerging health problem worldwide; however, the incidence of CRE varies greatly between different regions. Carbapenem resistance in Enterobacteriaceae is caused by different mechanisms, and CRE may display various resistance profiles. Bacterial co-expression of genes conferring resistance to both broad-spectrum β-lactam antibiotics (including carbapenems) and other classes of antibiotics may give rise to multidrug-resistant organisms (MDROs). The spread of CRE represents a major treatment challenge for clinicians due to lack of randomized clinical trials (RCTs), a limited number of antibiotics available, and the side-effects associated with them. Most research concerning CRE infections in AL patients are limited to case reports and retrospective reviews. Current research recommends treatment with older antibiotics, such as polymyxins, fosfomycin, older aminoglycosides, and in some cases carbapenems. To prevent the spread of resistant microbes, it is of pivotal interest to implement antibiotic stewardship to reduce broad-spectrum antibiotic treatment, but without giving too narrow a treatment to neutropenic infected patients.

Infective endocarditis by Klebsiella species: a systematic review

This study aimed to systematically analyze all cases of infective endocarditis (IE) by Klebsiella species in the literature. A systematic review of PubMed, Scopus and Cochrane library (through 27^th January 2021) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of IE by Klebsiella species was performed. In this review, a total of 66 studies were included, providing data for 67 patients. A prosthetic valve was present in 16.4%, while the most common causative pathogen was K. pneumoniae followed by K. oxytoca. The aortic valve was the most commonly infected intracardiac site, followed by the mitral valve. The diagnosis was based on transthoracic echocardiography in 46.2%, while the diagnosis was set at autopsy in 9.2% of included patients. Blood cultures were positive in 93.8%. Fever and sepsis were the most frequent clinical presentations, followed by embolic phenomena, paravalvular abscess, and heart failure. Cephalosporins, aminoglycosides, and carbapenems were the most frequently used antimicrobials. Surgical treatment along with antimicrobials was performed in 37.3% of included patients. Clinical cure was noted in 80.3%, while the overall mortality was 19.4%. Infection at the aortic valve was independently associated with mortality by IE. This systematic review gives a comprehensive description of IE by Klebsiella and provides information on epidemiology, clinical manifestations, therapeutic strategies and their outcomes.

Clinical Characteristics and Risk Factors for Critically Ill Patients with Carbapenem-Resistant Klebsiella pneumonia e (CrKP): A Cohort Study from Developing Country

BACKGROUND

Increasing evidence indicates carbapenem-resistant Klebsiella pneumoniae (CrKP) is increasingly prevalent in intensive care unit (ICU), but its clinical characteristics and risk factors remain unknown.

AIM

The aim of the present study was to evaluate clinical characteristics, risk factors in critically ill patients with CrKP infection.

METHODS

A retrospective study was included in patients from January 2013 to October 2019. Clinical data were collected from CrKP patients on the day of specimen collection admitted to ICU. Multivariable logistic regression was used for risk factors. Receiver operating curve (ROC) and the area under the curve (AUC) with DeLong method of MedCalc software were used. Two-way repeated-measures ANOVA analysis was used to analyze the characteristics of independent risk factors over time.

FINDINGS

A total of 147 adult patients with CrKP were screened, among them, 89 (median age 64.0 years, 66 (74.15%) males) patients with CrKP were finally included, of which 38 patients (42.7%) were non-survival group. Multivariate logistic regression analysis indicated that lactic acid (OR3.04 95% CI 1.38-6.68, P = 0.006), APACHE II score (OR 1.20, 95% CI 1.09-1.33, P < 0.001), tigecycline combined with fosfomycin treatment (OR0.15, 95% CI 0.04-0.65, P = 0.011) are independent risk factors for 28-day mortality in patients with CRKP infection (P<0.05). Combined lactic acid with APACHE II score could predict 28-day mortality, of which AUC value was 0.916 (95% CI, 0.847-0.985), with sensitivity 0.76 and specificity 0.98. ANOVA analysis showed that APACHE II score and lactic acid between the two groups at three-time points were statistically significant, which interactive with time and showed an upward and downward trend with time (P < 0.05).

CONCLUSION

Therapeutic strategy based on improving lactic acid and APACHE II would contribute to the outcome in patients with CrKP infection. Tigecycline combined with fosfomycin could reduce the 28-day mortality in patients with CrKP infection in developing country.

[Active screening of intestinal carbapenem-resistant Enterobacteriaceae in high-risk patients admitted to the hematology wards and its effect evaluation]

Objective: To evaluate the effect of intestinal carbapenem-resistant Enterobacteriaceae (CRE) active screening combined with enhanced intervention in the prevention and control of nosocomial infection in patients admitted to the hematological ward. Methods: Patients who were admitted to the Department of Hematology in a tertiary-care general hospital from March 1, 2017 to December 31, 2019 and underwent chemotherapy or immunosuppressive therapy comprised the intervention group. They were screened for intestinal CRE at least thrice. From December 1, 2016 to February 28, 2017, patients who underwent chemotherapy or immunosuppressive therapy without active intestinal CRE screening in the Department of Hematology formed the control group. Both the patient groups were monitored for CRE infection in real time. The χ(2) test was used to compare the changes in the CRE infection rate and mortality in high-risk patients before and after the active screening. Results: During the intervention period, the CRE colonization rate of patients was 16.46% (66/401) ; in terms of disease distribution, the colonization rate of acute leukemia was the highest 23.03% (26/113) . Of the 66 colonized patients, 27 (40.9%) patients were identified as positive for CRE at the first screening, 15 (22.7%) were identified at the time of the second screening, and the remaining 24 (36.4%) were identified at the third or subsequent screening; Carbapenem-resistant Klebsiella pneumoniae (CRPK) strains were dominant among the pathogens, accounting for 54.55% (36/66) . During the active screening period, the CRE infection rate (2.49%) and mortality rate (50.00%) of high-risk patients were significantly lower than those of the controls (11.30% and 69.23%, respectively) . The pathogens of 10 CRE infection patients during the intervention period were exactly the same as the previous active screening pathogens, and the coincidence rate was 100%. Conclusion: The CRE colonization rate was the highest in patients with acute leukemia who were admitted in the hematology wards. CRPK is the main pathogen of CRE colonization, infection, and death. Increasing the frequency of screening can significantly raise the positive rate of screening, Active screening can effectively reduce the incidence and subsequent mortality of CRE in high-risk patients admitted in the hematological wards. High coincidence rate between CRE screening positive pathogens and subsequent CRE infection pathogens. Intestinal CRE screening can serve as an indicator of CRE bloodstream infection in patients with hematological diseases as well as provide information for antibiotics therapy.

Clinical Characteristics and Risk Factors for Bloodstream Infection Due to Carbapenem-Resistant Klebsiella pneumoniae in Patients with Hematologic Malignancies

Purpose

The aim was to examine the clinical characteristics and risk factors for bloodstream infection (BSI) due to carbapenem-resistant Klebsiella pneumoniae (CRKP) in patients with hematologic malignancies.

Materials and Methods

A single-centre, retrospective case–control study representing 734 patients with hematologic malignancies between January 1, 2017, and December 31, 2018, was conducted. Demographic and clinical data were collected from the hospital electronic medical records system.

Results

Among the 734 patients with hematologic malignancies, 3% (22/734) of the patients developed CRKP BSI during their hospitalization. Overall 28-day all-cause mortality reached 77.3% (17/22). Patients with Pitt bacteremia score (PBS) >4, pneumonia and septic shock were more frequent in the non-survivors versus the survivors. Compared with the non-survivors in antimicrobial treatment, combination therapy of tigecycline and polymyxin B was more common in the survivors. The independent risk factors associated with CRKP BSI were CRKP rectal colonization (OR, 11.067; CI=4.43–27.644; P<0.001; 3 points), severe neutropenia (OR, 4.095; CI=0.876–19.141; P=0.073; 1 point) and invasive mechanical ventilation (IMV) within the previous 30 days to onset of BSI (OR, 18.444; CI=1.787–190.343; P=0.014; 4 points). The total risk score of ≥5 indicated that the probability of CRKP BSI occurrence was above 48%.

Conclusion

CRKP BSI in patients with hematologic malignancies is associated with high mortality. The risk factor-based prediction model might help clinicians to start prompt effective anti-infective therapy in patients with suspicion of CRKP BSI and improve outcomes.

Rectal colonization with multidrug-resistant gram-negative bacteria in patients with hematological malignancies: a prospective study

OBJECTIVES

To investigate the risk factors for rectal colonization with carbapenem-resistant Enterobacteriaceae (CRE) and extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) in hematological malignant patients with febrile neutropenia (FN); rate of rectal colonization and infection/colonization with CRE and ESBL-E; whether empirical treatment can be revised.

METHODS

Adult patients receiving chemotherapy were included. Rectal swab cultures of patients were screened for CRE and ESBL-E using selective chromogenic agars.

RESULTS

Fifty-seven FN episodes of 57 patients were studied. Rectal colonization rates were 40.4% (23/57) and 8.8% (5/57) for ESBL-E and CRE, respectively. ESBL-E bacteremia was diagnosed in 2 (8.6%) ESBL-E colonized patients, while CRE bacteremia was detected in 1 (20%) CRE colonized patient. Amikacin (100%) and carbapenem (93%) were the most effective antibiotics against gram-negative enteric bacteria. Beta-lactam usage within the last 3 months was a significant risk factor for ESBL-E colonization.

CONCLUSIONS

For the treatment of FN patients either colonized with ESBL-E or having significant risk factors for ESBL-E infection, aminoglycoside containing combinations may become an alternative to carbapenems due to their high sensitivity rates. When CRE colonized hematological cancer patients develop FN or if they are hemodynamically unstable, CRE covering empiric antibiotherapy should be preferred due to high mortality rates of CRE bacteremia.

Different screening frequencies of carbapenem-resistant Enterobacteriaceae in patients undergoing hematopoietic stem cell transplantation: which one is better?

BACKGROUND

A consensus has been reached that carbapenem-resistant Enterobacteriaceae (CRE) screening in immunosuppressed individuals can reduce the incidence of CRE bloodstream infection (BSI).

METHODS

We retrospectively studied the clinical data of 395 consecutive HSCT patients from September 2017 to April 2019. From September 2017 to June 2018 (period 1), 200 patients received single CRE screening before transplantation. From July 2018 to April 2019 (period 2), 195 patients received continuous weekly CRE screening after admission. For patients colonized with CRE, targeted managements were received: (1) contact precautions and (2) preemptive CRE-targeted treatment if necessary.

RESULTS

During period 1, 3 patients with CRE colonization were detected (1.5%). The CRE BSI rate was 2.0% (4 patients), and the related 30-day mortality was 50.0% (2 out of 4 patients). During period 2, 21 patients with CRE colonization were detected, and the detection rate was significantly higher than that in period 1 (P < 0.001). Of the 21 colonized patients, 4 (19.0%) patients were identified as positive for CRE at the first screening, 5 (23.8%) were identified at the second screening, and the remaining 12 (57.1%) were identified at the third or later screening. The CRE BSI rate decreased to 0.5% (1/195), and there were no CRE-related death. Fifteen colonized patients developed neutropenic fever. Thirteen colonizers were preemptively treated with tigecycline within 24 h of fever onset, and they achieved rapid temperature control. One colonizer received tigecycline later than 48 h after fever onset and ultimately survived due to the addition of polymyxin. The other received tigecycline later than 72 h after fever onset and died of septic shock.

CONCLUSION

The increase in screening frequency contributed to the detection of patients with CRE colonization. Targeted managements for these colonized patients may contribute to reducing the incidence and mortality of CRE BSI, therefore improving the prognosis of patients.

Proposal of a clinical score to stratify the risk of multidrug-resistant gram-negative rods bacteremia in cancer patients

Introduction

Multidrug-resistant gram-negative rods (MDR GNR) represent a growing threat for patients with cancer. Our objective was to determine the characteristics of and risk factors for MDR GNR bacteremia in patients with cancer and to develop a clinical score to predict MDR GNR bacteremia.

Material and Methods

Multicenter prospective study analyzing initial episodes of MDR GNR bacteremia. Risk factors were evaluated using a multiple logistic regression (forward-stepwise selection) analysis including variables with a p < 0.10 in univariate analysis.

Results

394 episodes of GNR bacteremia were included, with 168 (42.6 %) being MDR GNR. Five variables were identified as independent risk factors: recent antibiotic use (OR = 2.8, 95 % CI 1.7–4.6, p = 0.001), recent intensive care unit admission (OR = 2.9, 95 % CI 1.1–7.8, p = 0.027), hospitalization ≥ 7 days prior to the episode of bacteremia (OR = 3.5, 95 % CI 2–6.2, p = 0.005), severe mucositis (OR = 5.3, 95 % CI 1.8–15.6, p = 0.002), and recent or previous colonization/infection with MDR GNR (OR = 2.3, 95 % CI 1.2–4.3, p = 0.028). Using a cut-off value of two points, the score had a sensitivity of 66.07 % (95 % CI 58.4–73.2 %), a specificity of 77.8 % (95 % CI 71.4–82.7 %), a positive predictive value of 68 % (95 % CI 61.9–73.4 %), and a negative predictive value of 75.9 % (95 % CI 71.6–79.7 %). The overall performance of the score was satisfactory (AUROC 0.78; 95 % CI 0.73-0.82). In the cases with one or none of the risk factors identified, the negative likelihood ratio was 0.18 and the post-test probability of having MDR GNR was 11.68 %.

Conclusions

With the growing incidence of MDR GNR as etiologic agents of bacteremia in cancer patients, the development of this score could be a potential tool for clinicians.

Antimicrobial Stewardship in Hematological Patients at the intensive care unit: a global cross-sectional survey from the Nine-i Investigators Network

A global cross-sectional survey was performed to gather data on the current treatment of infections caused by multidrug-resistant (MDR) bacteria among hematological patients admitted to ICUs worldwide. The survey was performed in April 2019 using an electronic platform (SurveyMonkey®) being distributed among 83 physicians and completed by 48 (57.8%) responders. ESBL Enterobacteriaceae, carbapenem-resistant K. pneumoniae and carbapenem-resistant P. aeruginosa were the main concerns. Previous MDR infection (34% of responders), MDR colonization (20%) and previous antibiotic exposure within the last 3 months (20.5%) were considered the most relevant risk factors of bloodstream infection (BSI) due to MDR bacteria. In 48.8% of the ICUs, there was no antimicrobial stewardship (AMS) team focused on hematological patients. Updates on local epidemiology of MDR pathogens were provided in 98% of the centers, using phone or verbal communications (56.1% and 53.7%, respectively). In presence of febrile neutropenia, initial therapy consisted of anti-Gram-negative plus anti-Gram-positive antibiotics for 41% of participants. Antibiotic de-escalation and/or discontinuation of therapy were considered as a promising strategy for the prevention of MDR development (32.4%). Factors associated with antibiotic de-escalation were clinical improvement (43.6%) and neutrophil count recovery (12.8%). Infectious Disease consultation and AMS interventions were not determining factors for de-escalation decisions (more than 50% of responders). Infection control and educational programs were valued as necessary measures for implementation by ICU practitioners. These findings should guide future efforts on collaborative team working, improving compliance with adequate treatment protocols, implementing antimicrobial stewardship programs in critically ill hematological patients, and educational activities.

Direct use of eazyplex® SuperBug CRE assay from positive blood cultures in conjunction with inpatient infectious disease consulting for timely appropriate antimicrobial therapy in Escherichia coli and Klebsiella pneumoniae bloodstream infections

Objectives: To describe a rapid workflow based on the direct detection of Escherichia coli (Ec) and Klebsiella pneumoniae (Kp) producing CTX-M extended-spectrum β-lactamase (ESBL) and/or carbapenemases (eg, KPC, VIM) from blood cultures (BCs) and the infectious disease (ID) consulting for timely appropriate antimicrobial therapy. Methods: This observational, retrospective study included adult patients with a first episode of Ec or Kp bloodstream infection (BSI) in a large Italian university hospital, where an inpatient ID consultation team (IDCT) has been operational. Results from the BCs tested for detecting bla _CTX-M, bla _KPC, bla _NDM, bla _OXA-48-like, and bla _VIM genes by the eazyplex^® SuperBug CRE assay in Ec and Kp organisms had been notified for antimicrobial therapy consulting. Results: In 321 BSI episodes studied, we found that 151 (47.0%) of Ec or Kp organisms harbored bla _CTX-M and/or bla _KPC and/or bla _VIM (meantime from BC collection: 18.5 h). Empirical antimicrobial treatment was appropriate in 21.8% (33/151) of BSIs, namely 5.9% (3/51) of BSIs caused by KPC/VIM producers and 30.0% (30/100) of BSIs caused by CTX-M producers. After notification of results, the IDCT modified antimicrobial therapy (mean time from BC collection: 20 h) such that the proportion of appropriate treatments increased to 84.8% (128/151) of BSIs, namely 70.6% (36/51) of BSIs caused by KPC/VIM producers and 92.0% (92/100) of BSIs caused by CTX-M producers. Conclusion: Our study shows that a rapid diagnostic-driven clinical strategy allowed for early prescription of potentially effective antimicrobial therapy in BSIs caused by CTX-M ESBL- and/or KPC/VIM carbapenemase-producing Ec and Kp organisms.

Rethinking Antimicrobial Prophylaxis in the Transplant Patient in the World of Emerging Resistant Organisms-Where Are We Today?

PURPOSE OF REVIEW

The use of prophylactic antibiotics during the neutropenic period in hematopoietic stem cell transplantation has been the standard of care at most institutions for the past 20 years. We sought to review the benefits and risks of this practice.

RECENT FINDINGS

Emerging data has highlighted the potential costs of antibacterial prophylaxis, from selecting for antibiotic resistance to perturbing the microbiome and contributing to increase risk for Clostridium difficile and perhaps graft-versus-host-disease, conditions which may lead to poorer outcomes. Though in many studies prophylactic antibiotics improved morbidity and mortality outcomes, the potential harms including antibiotic resistance, Clostridium difficile infection, and alterations of the gut microbiome should be considered. Future studies aimed to better risk-stratify patients and limit the use of broad-spectrum antibiotics are warranted.

Modified combined disc test (mCDT): a novel, labor-saving and 4 times cheaper method to differentiate Class A, B and D carbapenemase-producing Klebsiella species

Carbapenemase-producing organisms have been an immense public health problem in recent years. Combined disc test (CDT) is a simple and widely used phenotypic method for carbapenemase detection, especially in developing countries. This study evaluates the performance of modified combined disc test (mCDT), a novel and 4 times cheaper method than CDT. In total, 572 (15.5%) Klebsiella spp. including 81 (14.2%) carbapenemase producers were isolated from 3993 clinical samples. Both mCDT and CDT showed similar sensitivity, specificity, positive predictive value, and negative predictive value for the differentiation of Class A, B, and D carbapenemase-producing Klebsiella spp.

Clinical Impact of Pretransplant Multidrug-Resistant Gram-Negative Colonization in Autologous and Allogeneic Hematopoietic Stem Cell Transplantation

Multidrug-resistant Gram-negative bacteria (MDR-GNB) are an emerging cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Three-hundred forty-eight consecutive patients transplanted at our hospital from July 2012 to January 2016 were screened for a pretransplant MDR-GNB colonization and evaluated for clinical outcomes. A pretransplant MDR-GNB colonization was found in 16.9% of allo-HSCT and in 9.6% of auto-HSCT recipients. Both in auto- and in allo-HSCT, carriers of a MDR-GNB showed no significant differences in overall survival (OS), transplant-related mortality (TRM), or infection-related mortality (IRM) compared with noncarriers. OS at 2 years for carriers compared with noncarriers was 85% versus 81% (P = .262) in auto-HSCT and 50% versus 43% (P = .091) in allo-HSCT. TRM at 2 years was 14% versus 5% (P = .405) in auto-HSCT and 31% versus 25% (P = .301) in allo-HSCT. IRM at 2 years was 14% versus 2% (P = .142) in auto-HSCT and 23% versus 14% (P = .304) in allo-HSCT. In multivariate analysis, only grade III to IV acute graft-versus-host disease was an independent factor for reduced OS (P < .001) and increased TRM (P < .001) and IRM (P < .001). During the first year after transplant, we collected 73 GNB bloodstream infectious (BSI) episodes in 54 patients, 42.4% of which sustained by a MDR-GNB. Rectal swabs positivity associated with the pathogen causing subsequent MDR-GNB BSI episodes in 13 of 31 (41.9%). Overall, OS at 4 months from MDR-GNB BSI episode onset was of 67.9%, with a 14-day attributed mortality of 12.9%, not being significantly different between carriers and noncarriers (P = .207). We conclude that in this extended single-center experience, a pretransplant MDR-GNB colonization did not significantly influence OS, TRM, and IRM both in auto- and allo-HSCT settings and that MDR-GNB attributed mortality can be controlled in carriers when an early pre-emptive antimicrobial therapy is started in case of neutropenic fever.

Prevalence and risk factors of Gram-negative bacilli causing blood stream infection in patients with malignancy

Objectives:

To evaluate the epidemiology, risk factors, and antibiotic resistance of Gram negative bacteria (GNB) in patients with hematologic or solid organ malignancies.

Methods:

This is a retrospective study of 61 episodes of GNB bacteremia occurring in 56 patients with malignancy admitted to the Oncology Units in King Khalid University Hospital, Riyadh. Kingdom of Saudi Arabia during the period from January 2013 to October 2015. Data were retrieved from the computerized database of the microbiology laboratory and the patient’s medical records.

Results:

Hematological malignancies accounted for 30 (54%) and solid tumors accounted for 26 (46%). The most common hematological malignancies were leukemia 23 (77%), followed by lymphoma 6 (20%). Among solid tumors, colorectal cancer 9 (34.6) and breast cancer 6 (23%) were the most common. The most predominant pathogen was Escherichia coli (E. coli) (29.5%) followed by Acinetobacter baumannii (A. baumannii) (18%). The extended-spectrum beta-lactamases producers rate of E. coli and Klebsiella pneumonia was (34.6%). Imipenem resistance among Pseudomonas aeruginosa/A. baumannii was high (52.4%). The multi-resistant organisms rate was (43.5%). Risk factors associated with the bacteremia were ICU admission (32.1%), post-surgery (23.2%), and placement of central line (21.4%). The overall 30-day mortality rate of the studied population was high (32.1%).

Conclusion:

In light of the high resistant rate among the GNB isolated from malignancy patients from our institution, careful selection of antimicrobial treatment based on antimicrobial susceptibility testing is recommended.

Complications of hematopoietic stem cell transplantation: Bacterial infections

Bacterial infections remain a common complication of hematopoietic stem cell transplantation (HSCT), especially in the pre-engraftment phase. The risk of bacterial infections is mainly related to neutropenia, mucositis, and the presence of vascular lines. Most parts of the world have witnessed a shift in epidemiology toward Gram-negative bacteria; a large proportion of which are resistant to fluoroquinolones, extended-spectrum beta-lactams, carbapenems, and in some units even colistin. Meticulous infection control practices are essential for prevention of bacterial infections in HSCT. The role of routine prophylactic antibiotics is limited in settings with high rates of bacterial resistance. If used, prophylactic antibiotics should be limited to high-risk patients, and the agents are selected based on local resistance profiles. Neutropenic fever is a medical emergency in most HSCT recipients. Prompt clinical evaluation is paramount, along with the intravenous administration of appropriate empiric antimicrobials, typically an antipseudomonal beta-lactam agent. Glycopeptides should only be considered if the patient is hemodynamically unstable or Gram-positive infection is suspected. Additional Gram-negative agents, such as colistin or aminoglycosides, may be added if extensive Gram-negative resistance is expected. To mitigate increasing bacterial resistance, empiric antibiotic regimens should be rationalized or discontinued as soon as possible.

Hospital-Associated Infections

Hospital-associated infection (HAI) in immunocompromised patients can result in high rates of morbidity and mortality. Infections caused by multidrug-resistant organisms (MDROs) are especially worrisome because of the limited choice of remaining antibiotics available when a patient becomes colonized or infected with an MDRO. It is therefore important that immunocompromised patients be cared for in an environment that limits the risk for acquiring infections. However, with healthcare being increasingly delivered in settings other than the traditional inpatient hospital wards, a bigger effort will need to be set forth to prevent or rapidly diagnose HAI. The last few years have seen a significant increase in the number of singleplex and multiplex molecular assays for the detection of many of the organisms responsible for HAI, but more is needed as infections caused by organisms like Legionella pneumophila and Aspergillus species are still diagnosed with methods that have relatively low yield and are slow to provide actionable results. Finally, the use of novel techniques for outbreak investigations will provide new information on transmission of infectious agents in healthcare settings and allow stronger, evidence-based recommendations to be developed for prevention of HAIs in the immunocompromised host.

Carbapenem-resistant Enterobacteriaceae in special populations: Solid organ transplant recipients, stem cell transplant recipients, and patients with hematologic malignancies

Carbapenem-resistant Enterobacteriaceae (CRE) are a major global public health concern and pose a serious threat to immunocompromised hosts, particularly patients with hematologic malignancies and solid organ (SOT) and stem cell transplant recipients. In endemic areas, carbapenem-resistant Klebsiella pneumoniae infections occur in 1-18% of SOT recipients, and patients with hematologic malignancies represent 16-24% of all patients with CRE bacteremia. Mortality rates approaching 60% have been reported in these patient populations. Early diagnosis and rapid initiation of targeted therapy is critical in the management of immunocompromised hosts with CRE infections, as recommended empiric regimens are not active against CRE. Therapeutic options are limited by antibiotic-associated toxicities, interactions with immunosuppressive agents, and paucity of antibiotic options currently available. Prevention of CRE infection in these patients requires a multidisciplinary approach involving hospital epidemiology and antimicrobial stewardship. Large, multicenter studies are needed to develop risk-stratification tools to assist in guiding the management of these individuals.

Carbapenem-resistant Klebsiella pneumoniae in high-risk haematological patients: factors favouring spread, risk factors and outcome of carbapenem-resistant Klebsiella pneumoniae bacteremias

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae (CRKP) spread and infections in patients with haematological malignancies are a serious concern especially in endemic areas. Treatment failures and delay in appropriate therapy for CRKP infections are frequent and the mortality rate associated with CRKP bacteremia in neutropenic haematological patients is reported about 60%.

METHODS

Haematological patients harboring CRKP hospitalized between February 2012 and May 2013 in an Italian Teaching hospital were examined. Conditions favouring CRKP spread in a haematological unit, risk factors for bacteremia in CRKP-carriers and for CRKP bacteremia-related death were evaluated in this observational retrospective study.

RESULTS

CRKP was isolated in 22 patients, 14 (64%) had bacteremia. Control measures implementation, particularly the weekly rectal screening for CRKP performed in all hospitalized patients and contact precautions for CRKP-carriers and newly admitted patients until proved CRKP-negative, reduced significantly the CRKP spread (14 new carriers identified of 131 screened patients vs 5 of 242 after the intervention, p = 0.001). Fifty-eight percent of carriers developed CRKP bacteremia, and acute myeloid leukemia (AML) resulted independently associated with the bacteremia occurrence (p = 0.02). CRKP bacteremias developed mainly during neutropenia (86%) and in CRKP-carriers (79%). CRKP bacteremias were breakthrough in 10 cases (71%). Ten of 14 patient with CRKP bacteremias died (71%) and all had AML. The 70% of fatal bacteremias occurred in patients not yet recognized as CRKP-carriers and 80% were breakthrough. Initial adequate antibiotic therapy resulted the only independent factor able to protect against death (p = 0.02).

CONCLUSIONS

The identification of CRKP-carriers is confirmed critical to prevent CRKP spread. AML patients colonized by CRKP resulted at high risk of CRKP-bacteremia and poor outcome and the adequacy of the initial antibiotic therapy may be effective to improve survival. To limit the increase of resistance, the extensive use of antibiotics active against CRKP should be avoided, but in the setting of high CRKP pressure and high-risk CRKP-colonized haematological patients, timely empiric antibiotic combinations active against CRKP could be suggested as treatment of febrile neutropenia.

Bloodstream infections caused by Klebsiella pneumoniae in onco-hematological patients: clinical impact of carbapenem resistance in a multicentre prospective survey

The aim of this study was to identify risk factors for mortality in patients suffering from hematological malignancies (HMs) with bloodstream infections (BSIs) caused by Klebsiella pneumoniae (KP). We conducted a prospective cohort study on KP BSI in 13 Italian hematological units participating in the HEMABIS registry-SEIFEM group. The outcome measured was death within 21 days of BSI onset. Survivor and non-survivor subgroups were compared and Cox regression analysis was conducted to identify independent predictors of mortality. A total of 278 episodes of KP BSI were included in the study between January 2010 and June 2014. We found that 161 (57.9%) KP isolates were carbapenem resistant (CRKP). The overall 21-day mortality rate was 36.3%. It was significantly higher for patients with CRKP BSI (84/161, 52.2%) than for those with BSI caused by carbapenem susceptible KP (CSKP) (17/117, 14.5%; P < 0.001). Septic shock (HR 3.86), acute respiratory failure (HR 2.32), inadequate initial antimicrobial therapy (HR 1.87) and carbapenem resistance by KP isolates (HR 1.85) were independently associated with mortality. A subanalysis was conducted in only 149 patients with CRKP BSI who had received ≥48 hr of adequate antibiotic therapy, and combination therapy was independently associated with survival (HR 0.32). Our study shows that in recent years carbapenem resistance has dramatically increased in HM patients with KP BSI in Italy and is associated with a worse outcome. The optimal management of such infections and the definition of new empirical/targeted antimicrobial strategies in HM patients can still be considered unmet clinical needs. Am. J. Hematol. 91:1076-1081, 2016. © 2016 Wiley Periodicals, Inc.

The growing threat of multidrug-resistant Gram-negative infections in patients with hematologic malignancies

Prolonged neutropenia and chemotherapy-induced mucositis render patients with hematologic malignancies highly vulnerable to Gram-negative bacteremia. Unfortunately, multidrug-resistant (MDR) Gram-negative bacteria are increasingly encountered globally, and current guidelines for empirical antibiotic coverage in these patients may not adequately treat these bacteria. This expansion of resistance, coupled with traditional culturing techniques requiring 2-4 days for bacterial identification and antimicrobial susceptibility results, have grave implications for these immunocompromised hosts. This review characterizes the epidemiology, risk factors, resistance mechanisms, recommended treatments, and outcomes of the MDR Gram-negative bacteria that commonly cause infections in patients with hematologic malignancies. We also examine the infection prevention strategies in hematology patients, such as infection control practices, antimicrobial stewardship, and targeted decolonization. Finally, we assess the strategies to improve outcomes of the infected patients, including gastrointestinal screening to guide empirical antibiotic therapy, new rapid diagnostic tools for expeditious identification of MDR pathogens, and use of two new antimicrobial agents, ceftolozane/tazobactam and ceftazidime/avibactam.

Epidemiology of Carbapenem Resistant Klebsiella pneumoniae Infections in Mediterranean Countries

Infections by Carbapenem-Resistant Enterobacteriaceae (CRE), in particular, carbapenem-resistant Klebsiella pneumoniae (CRKp), are a significant public health challenge worldwide. Resistance to carbapenems in enterobacteriaceae is linked to different mechanisms, including the production of the various types of enzymes like KPC, VIM, IMP, NDM, and OXA-48. Despite several attempts to control the spread of these infections at the local and national level, the epidemiological situation for CRKp had worsened in the last years in the Mediterranean area. The rate and types of CRKp isolates greatly differ in the various Mediterranean countries. KPC-producing K. pneumoniae is diffused particularly in the European countries bordering the Mediterranean Sea and is endemic in Greece and Italy. On the contrary, OXA-48-producing K. pneumoniae is endemic in Turkey and Malta and diffused at inter-regional level particularly in some

North African and Middle East countries. The spread of these multiresistant pathogens in the world and the Mediterranean countries has been related to various epidemiological factors including the international transfer of patients coming from endemic areas.

The challenge of antibiotic resistance in haematology patients

Bacterial infections were once a major obstacle to the treatment of acute leukaemia. Improvement in management strategies, including the use of broad-spectrum antibacterial drugs targeting Gram-negative bacteria, has reduced the mortality in neutropenic patients developing blood stream infections and other severe infections. In many countries these achievements are threatened by development of multi-resistant bacteria, such as Klebsiella pneumoniae, Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. This review addresses the epidemiology, clinical importance and possible management of these multi-resistant organisms.

New Insight on Epidemiology and Management of Bacterial Bloodstream Infection in Patients with Hematological Malignancies

Bloodstream infections (BSI) are a significant cause of morbidity and mortality in onco-hematologic patients. The Gram-negative bacteria were the main responsible for the febrile neutropenia in the sixties; their impact declined due to the use of fluoroquinolone prophylaxis. This situation was followed by the gradual emergence of Gram-positive bacteria also following the increased use of intravascular devices and the introduction of new chemotherapeutic strategies. In the last decade, the Gram-negative etiology is raising again because of the emergence of resistant strains that make questionable the usefulness of current strategies for prophylaxis and empirical treatment. Gram-negative BSI attributable mortality is relevant, and the appropriate empirical treatment significantly improves the prognosis; on the other hand the adequate delayed treatment of Gram-positive BSI does not seem to have a high impact on survival. The clinician has to be aware of the epidemiology of his institution and colonizations of his patients to choose the most appropriate empiric therapy. In a setting of high endemicity of multidrug-resistant infections also the choice of targeted therapy can be a challenge, often requiring strategies based on off-label prescriptions and low grade evidence.

In this review, we summarize the current evidence for the best targeted therapies for difficult to treat bacteria BSIs and future perspectives in this topic. We also provide a flow chart for a rational approach to the empirical treatment of febrile neutropenia in a multidrug resistant, high prevalence setting.

Antibiofilm peptides increase the susceptibility of carbapenemase-producing Klebsiella pneumoniae clinical isolates to β-lactam antibiotics

Multidrug-resistant carbapenemase-producing Klebsiella pneumoniae (KpC) strains are becoming a common cause of infections in health care centers. Furthermore, Klebsiella can develop multicellular biofilms, which lead to elevated adaptive antibiotic resistance. Here, we describe the antimicrobial and antibiofilm activities of synthetic peptides DJK-5, DJK-6, and 1018 against five KpC isolates. Using static microplate assays, it was observed that the concentration required to prevent biofilm formation by these clinical isolates was below the MIC for planktonic cells. More-sophisticated flow cell experiments confirmed the antibiofilm activity of the peptides against 2-day-old biofilms of different KpC isolates, and in some cases, the peptides induced significant biofilm cell death. Clinically relevant combinations of DJK-6 and β-lactam antibiotics, including the carbapenem meropenem, also prevented planktonic growth and biofilm formation of KpC strain1825971. Interestingly, peptide DJK-6 was able to enhance, at least 16-fold, the ability of meropenem to eradicate preformed biofilms formed by this strain. Using peptide DJK-6 to potentiate the activity of β-lactams, including meropenem, represents a promising strategy to treat infections caused by KpC isolates.