In vitro activity of aztreonam-avibactam against metallo-β-lactamase-producing Enterobacteriaceae-A multicenter study in China

OBJECTIVES

To study the molecular epidemiology of clinical metallo-β-lactamase (MBL)-producing Enterobacteriaceae isolates in China and to evaluate the antimicrobial susceptibility of MBL-Enterobacteriaceae isolates to aztreonam-avibactam.

METHODS

Bacterial speciation was determined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. PCR was used to screen for common carbapenemase genes. Antimicrobial susceptibility testing of common clinical antibiotics and aztreonam-avibactam was performed using the standard broth microdilution method.

RESULTS

A total of 161 MBL-Enterobacteriaceae isolates were included, with Klebsiella pneumoniae (n = 73, 45.4%) and Escherichia coli (n = 53, 32.9%) being the most common species. Among the 161 isolates, bla_NDM (n = 151), bla_IMP (n = 13), and bla_VIM (n = 2) were detected, including five strains (3.1%) co-harboring two MBLs. MBL-Enterobacteriaceae isolates frequently contained two (n = 55, 34.2%) or more (n = 89, 55.3%) additional serine β-lactamase genes (bla_KPC, bla_CTX-M, bla_TEM, or bla_SHV). Antimicrobial susceptibility testing showed that 81.4% of isolates (n = 131) were resistant to aztreonam. The rates of resistance to cefazolin, ceftazidime, ceftriaxone, cefotaxime, ampicillin-sulbactam, amoxicillin-clavulanic acid, and piperacillin-tazobactam were all over 90%. The addition of avibactam (4 μg/ml) significantly reduced the minimum inhibitory concentrations (MICs) of the aztreonam-resistant isolates by more than 8-fold (range ≤0.125 to 4 μg/ml), with a MIC₅₀/MIC₉₀ of ≤0.125/1 μg/ml among the 131 isolates. Overall, 96.9% (n = 156) of the total isolates were inhibited at an aztreonam-avibactam concentration of ≤1 μg/ml. Univariate and multivariate logistic regression analysis found that in patients with MBL-Enterobacteriaceae infections, the presence of pre-existing lung disease (adjusted odds ratio 8.267, 95% confidence interval 1.925-28.297; p = 0.004) was associated with a hazard effect on worse disease outcomes.

CONCLUSIONS

The combined use of aztreonam-avibactam is highly potent against MBL-Enterobacteriaceae and may serve as a new candidate for the treatment of infections caused by MBL-Enterobacteriaceae in China.

Carbapenem-Resistant Klebsiella aerogenes Clinical Isolates from a Teaching Hospital in Southwestern China: Detailed Molecular Epidemiology, Resistance Determinants, Risk Factors and Clinical Outcomes

Purpose

Little is known about the epidemiology and carbapenem-resistance determinants of carbapenem-resistant K. aerogenes (CRKA) isolated from a single medical center. The present study was initiated to characterize the molecular epidemiology and the carbapenem-resistance mechanisms of CRKA isolated during 2012–2018 from a teaching hospital in southwest China, and to investigate the risk factors and clinical outcomes of CRKA infections as well.

Methods

Pulsed-field gel electrophoresis (PFGE) was employed for epidemiological analysis. PCR amplification and DNA sequencing were used to examine the antibiotic-resistance determinants. Plasmids were extracted and characterized by PCR-based replicon typing and conjugation assays. In order to further investigate the risk factors and clinical outcomes of CRKA infections, a retrospective case–control study was also performed.

Results

PFGE analysis showed 32 different PFGE patterns among the 36 non-duplicated CRKA strains collected. Most of the isolates harbored multi-drug resistance (MDR) genes, including 2 (5.6%) carrying bla_NDM-1, 1 (2.8%) harboring bla_KPC-2, 13 (36.1%) carrying ESBL genes, 23 (63.9%) carrying ampC genes, 34 (94.4%) carrying quinolone resistance determinants (QRD) genes and 9 (25%) carrying aminoglycoside resistance determinants (ARD) genes. The outer membrane porins, OmpE35 and OmpE36, were, respectively, lost in 4 and 2 isolates. The efflux pump inhibition experiments were positive in 25 (69.4%) of the CRKA strains. Multivariate analysis indicated that hypo-albuminaemia, invasive procedures, and carbapenem exposure were independent risk factors for acquiring CRKA infections.

Conclusion

No clonality relationship was identified among most of the 36 CRKA isolates. The over-expression of ESBLs and AmpC coupled with the efflux pumps contributed to carbapenem resistance in K. aerogenes. Additionally, this is the first report of CRKA isolate co-harboring bla_NDM-1, bla_CTX-M-15, bla_EBC, bla_ACC, acc (6ʹ)-Ib, armA, qnrD and loss of OmpE36 in China. Hypo-albuminaemia, invasive procedures and carbapenem exposure were associated with acquisition of CRKA infections.

Carbapenem-resistant Enterobacteriaceae: A retrospective review of treatment and outcomes in a long-term acute care hospital

BACKGROUND

Long-term acute care hospitals (LTACHs) have a unique patient population, with multiple risk factors for carbapenem-resistant Enterobacteriaceae (CRE) colonization and infection.

METHODS

We performed a retrospective analysis of patients in LTACHs who were diagnosed with and treated for CRE infections. Baseline data, antimicrobial treatment, and outcomes were collected in patients with bacteremia, health care-associated pneumonia, and complicated urinary tract infection/acute pyelonephritis due to CRE diagnosed between January 2017 and December 2017.

RESULTS

A total of 57 cases of CRE infection were identified over the study period, including 12 cases of bacteremia, 20 cases of health care-associated pneumonia, and 25 cases of complicated urinary tract infection/acute pyelonephritis. Patient had significant comorbidities: 31.5% with diabetes, 40.4% with heart failure, 29.8% with kidney disease, and 10% with solid tumors. The majority (56) of 57 patients received empiric antibiotics known to have activity against gram-negative bacteria, but only 38.6% had in vitro activity against the CRE organism in cultured specimens. A total of 78.9% of patients received monotherapy. Overall outcome was poor, with 28-day mortality across all infection sites of 17.5% in patients but up to 25% in patients with bacteremia.

CONCLUSIONS

In this retrospective analysis of our clinical experience treating CRE infections in an LTACH setting, we documented that CRE infections occur in patients with substantial comorbidities. Although clinical outcome remains of great concern, the 28-day mortality and rate of eradication of CRE in this study were comparatively better than other national estimates. Inappropriate empiric treatment may be one of many factors leading to overall poor treatment outcomes.

Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance

The genus Enterobacter is a member of the ESKAPE group, which contains the major resistant bacterial pathogens. First described in 1960, this group member has proven to be more complex as a result of the exponential evolution of phenotypic and genotypic methods. Today, 22 species belong to the Enterobacter genus. These species are described in the environment and have been reported as opportunistic pathogens in plants, animals, and humans. The pathogenicity/virulence of this bacterium remains rather unclear due to the limited amount of work performed to date in this field. In contrast, its resistance against antibacterial agents has been extensively studied. In the face of antibiotic treatment, it is able to manage different mechanisms of resistance via various local and global regulator genes and the modulation of the expression of different proteins, including enzymes (β-lactamases, etc.) or membrane transporters, such as porins and efflux pumps. During various hospital outbreaks, the Enterobacter aerogenes and E. cloacae complex exhibited a multidrug-resistant phenotype, which has stimulated questions about the role of cascade regulation in the emergence of these well-adapted clones.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

The use of predictive scores in the management of patients with carbapenem-resistant Klebsiella pneumoniae infection

INTRODUCTION

Carbapenem-resistant Klebsiella pneumoniae (CR-KP) infections are associated with high morbidity and mortality rates. A therapeutic approach based on the patient risk stratification could improve outcome and avoid antibiotic misuse. Areas covered: English literature search, from 2008 to 2018, was done using PubMed database. Risk factors for developing CR-KP infection in several settings were reviewed. Since, rectal carriage was a main risk factor for developing infection, we revised in deep clinical score to predict infection among colonized patients. Furthermore, we investigated overall and treatment-related risk factors for poor outcome in patients with CR-KP infection, in particular the carbapenem producing Enterobacteriacieae (CPE)-INCREMENT score. Finally, an algorithm, based on such scores, for the therapeutic management of patients with CR-KP colonization was commented. Expert opinion: The therapeutic approach analyzed in this review could help physicians to avoid antibiotic overuse as well as to start promptly with the most appropriate antibiotic regimen. However, it has to be validated in further studies, mainly among special population such as immunocompromised patients. The availability of new drugs, fast microbiology, and analysis of gut microbiome could significantly improve the management of CR-KP colonized and/or infected patients.

The antibiotic arms race: current and emerging therapy for Klebsiella pneumoniae carbapenemase (KPC) - producing bacteria

Introduction: The rapid spread of Klebsiella pneumoniae Carbapenemase (KPC)-producing bacteria comprises one of the greatest challenges to global health. Historically, clinicians were limited to therapies with suboptimal efficacy and intolerable toxicity until the FDA approved ceftazidime-avibactam and meropenem-vaborbactam, adding two essential pharmacotherapies to our antibiotic armamentarium. These agents display superior efficacy and safety compared to historical treatment options; however, resistance has already been reported. Several antimicrobials currently in the drug pipeline exhibit early promise and may fill needed gaps in therapy. Areas covered: This article encompasses both the past and present treatment options for the management of KPC-producing bacterial infections via an extensive review and critical appraisal of the current literature. Expert opinion: Traditional treatment options can no longer be recommended as first-line options for the management of KPC-producing bloodstream infections. Ceftazidime-avibactam or meropenem-vaborbactam plus or minus an aminoglycoside or polymyxin should be utilized as backbone therapies given their superior efficacy and safety profiles when compared to traditional treatment options. For susceptible KPC-producing urinary tract infections, it is reasonable to consider treatment with an aminoglycoside or with fosfomycin as a monotherapy. All of these decisions should be based on patient-specific characteristics, severity of infection and source control, susceptibility patterns, and input from infectious diseases experts.

Ertapenem non-susceptibility and independent predictors of the carbapenemase production among the Enterobacteriaceae isolates causing intra-abdominal infections in the Asia-Pacific region: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART)

Objectives

This study investigated the prevalence rates of carbapenemase positivity, antibiotic susceptibility, and independent predictors of carbapenemase producers among the Enterobacteriaceae isolates recovered from patients with intra-abdominal infections (IAI) in the Asia-Pacific region between 2008 and 2014.

Materials and methods

Multiplex PCR was used for the detection of specific β-lactamases, while the broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of antibiotics among the IAI-related Enterobacteriaceae isolates. We studied the abovementioned parameters in 484 ertapenem-non-susceptible (Erta-NS) isolates and explored the independent predictors of carbapenemase-producing Enterobacteriaceae (CPE) isolates.

Results

Eighty (16.5%) Erta-NS-IAI Enterobacteriaceae isolates were found to be CPE. Vietnam and the Philippines had the highest CPE prevalence rates. The IAI isolates of Enterobacter species and Klebsiella pneumoniae followed by Escherichia coli were the three major pathogens with 77.4%, 40.9%, and 11.7% Erta-NS prevalence rates, respectively. Furthermore, the highest CPE prevalence (35%) was noted among the Erta-NS-K. pneumoniae isolates. The CPE isolates harboring the bla_NDM, bla_KPC, or blaOXA-48-like alleles had higher imipenem MIC levels than those harboring the bla_IMP alleles. Using multivariate logistic regression analysis, we concluded that Erta-NS-IAI isolates with an imipenem non-susceptible phenotype (OR, 56.4), with cefepime MIC >8 µg/mL (OR, 4.4), cultured from the peritoneal space samples (tissue or abscess; OR, 3.3), and harboring the extended-spectrum β-lactamase encoding allele (OR, 11.5) are independent predictors of CPE.

Conclusion

Imipenem non-susceptibility, cefepime MIC >8 µg/mL, and the peritoneal space as a culture site are independent clinical predictors of CPE among the Erta-NS-IAI Enterobacteriaceae isolates in the Asia-Pacific region.

Epidemiology of and risk factors for infection with extended-spectrum β-lactamase-producing carbapenem-resistant Enterobacteriaceae: results of a double case-control study

Purpose

Carbapenem-resistant Enterobacteriaceae (CRE) have been increasingly reported worldwide and pose a serious public threat, but the clinical significance of extended-spectrum β-lactamase (ESBL) production in CRE is not well established.

Patients and methods

A retrospective case–case–control study was conducted to identify the clinical characteristics of patients with ESBL-CRE. The susceptibility of isolates obtained from these patients was assessed. The detection of ESBL and carbapenemase-related genes was performed by PCR methods. Predictors of 30-day mortality in patients with ESBL-CRE infection were also identified in our study.

Results

A total of 149 patients with CRE infection caused by Enterobacter cloacae (n=74), Escherichia coli (n=38), and Klebsiella pneumoniae (n=37) were identified in Chongqing, Southwestern China, between January 2011 and December 2014. Of the 35 isolates detected with carbapenemase-related genes, 16 isolates had New Delhi metallo-β-lactamase (NDM), nine isolates had K. pneumoniae carbapenemase (KPC), seven isolates had imipenemase (IMP), and four isolates had oxacillinase (OXA)-1. One strain of enterobacter cloacae carried both NDM-1 and IMP-8 genes. ESBL isolates included the genes CTX-M (72/149), SHV (64/149), and TEM (54/149). All ESBL-CRE isolates exhibited ertapenem resistance, and the rate of cephalosporin resistance was relatively high in general. Independent risk factors for infection with ESBL-CRE included previous exposure to β-lactam antibiotics, transfer from another hospital, and some underlying diseases. In addition, solid tumors, hypoalbuminemia, and central venous catheters were independent predictors of mortality in patients with ESBL-CRE infection.

Conclusion

Physicians should understand the peculiar predictors for the identification of these organisms among high-risk patients.

Carbapenem-Resistant E. cloacae in Southwest China: Molecular Analysis of Resistance and Risk Factors for Infections Caused by NDM-1-Producers

Carbapenem-resistant Enterobacteriaceae (CRE) has been considered a serious global threat, but carbapenem resistance remains relatively uncommon in E. cloacae, especially in China. The aim of this study was to characterize carbapenem-resistant E. cloacae (CR-ECL) isolates from 2012 to 2016 in Southwest China. Our study revealed that 20 (15.2%) of the 132 CR-ECL isolates obtained from patients were identified as NDM-1, with most isolates carrying the IncFIIA plasmids. Notably, we initially observed that the E. cloacae strain co-harbored NDM-1 and IMP-8 carbapenemases simultaneously. Analysis of the genetic environment of these two genes has revealed that the highly conserved regions (bla_NDM-1-ble_MBL-trpF-tat) are associated with the dissemination of NDM-1, while IS26, intI1, and tniC could be involved in the spread of IMP-8. Molecular epidemiology studies showed the nosocomial outbreak caused by NDM-1-producing E. cloacae ST88. Transferring from another hospital and previous carbapenem exposure were identified as independent risk factors for the acquisition of NDM-1-producing E. cloacae. These findings emphasize the need for intensive surveillance and precautions to monitor the further spread of NDM-1 in China.

Risk factors and mortality in the Carbapenem-resistant Klebsiella pneumoniae infection: case control study

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has been known as a nosocomial pathogen, both for the last 10 years in Turkey and for 20 years worldwide. Due to limited treatment options and high mortality rates, despite improvements in the field of medicine at the present time, CRKP is still a big threat for public health. This study was carried out between the dates of January 2010 and September 2014. Patients ≥18 who were hospitalized for at least 72 h and who also had CRKP growth were included in the study as a case group. In the same period patients, who were hospitalized in the same ward and did not have CRKP growth were selected as the control group. It was determined that no glycopeptides and steroids use nor tracheostomy as protective factors would be employed in terms of non-development of CRKP. Mechanical ventilation, tracheostomy, urinary catheter presence, central venous catheterization, nasogastric tube placement, advanced age, acute renal insufficiency, total parenteral nutrition, carbapenem, glycopeptide, and piperacillin tazobactam were all detected as risk factors in terms of CRKP infection development. As a result, rational usage of antibiotics for preventing infections developing with CRKP should be targeted.

Ertapenem resistance in 2 tertiary-care hospitals: Microbiology, epidemiology, and risk factors

INTRODUCTION

Carbapenems resistance is a growing phenomenon and a threat to public health because of the reduced therapeutic options for resistant infections.

METHODS

A retrospective case-control study was conducted in 2 tertiary-care hospitals in Medellín, Colombia. Fifty patients infected with ertapenem-resistant enterobacteriaceae were compared with a control group consisting of 100 patients with infections caused by ertapenem susceptible enterobacteriaceae. A multivariate logistic regression model was used to identify factors that best explain ertapenem-resistant enterobacteriaceae infections.

RESULTS

The factors associated with ertapenem-resistant enterobacteriaceae infections were prior exposure to carbapenems (adjusted OR 3.43; 95% IC 1.08-10.87) and prior exposure to cefepime (adjusted OR 6.46; 95% IC 1.08-38.38).

CONCLUSION

Prior exposure to antibiotics is the factor that best explains the ertapenem-resistant enterobacteriaceae infection in this population, highlighting the importance of antimicrobial stewardship programs in hospitals.

Efficacy of an Enrichment Media for Increasing Threshold for Carbapenem-Resistant Enterobacteriaceae Screening

BACKGROUND

Identification of carbapenem-resistant Enterobacteriaceae (CRE) is complex and a major laboratory challenge; clinical cultures may diagnose only some of the CRE carriers among patients, thus it is crucial to perform asymptomatic carriage screening.

MATERIALS AND METHODS

 We compare the efficacy of a rectal sample culture prior to enrichment with BHI (Brain Heart Infusion) Broth and following 18-24 h. All rectal samples were applied on CHROMagar KPC selective growth media and then seeded on MacConkey agar selective growth media with an applied disk of Imipenem antibiotic on top of the media, then inserted into enrichment BHI Broth. After 18-24 h incubation with enrichment media, all samples were applied again on this media.

RESULTS

From the 2,245 rectal samples, CRE colonies were found in 96 (4.3%). Following enrichment with BHI Broth, CRE colonies were found in 111 (4.9%) CHROMagar KPC plates and 106 (4.7%) MacConkey agar.

CONCLUSION

We were able to demonstrate that the number of CRE-positive results increased due to use of additional enrichment with BHI Broth. Therefore, we recommend applying this method of addition of liquid enrichment media as part of a culture protocol routine for CRE screening.

Empirical therapies among adults hospitalized for community-acquired upper urinary tract infections: A decision-tree analysis of mortality, costs, and resistance

BACKGROUND

Poor outcomes occur when patients with serious infections receive antibiotics to which the organisms are resistant.

METHODS

Decision trees simulated in-hospital mortality, costs, incremental cost-effectiveness ratio per life year saved, and carbapenem resistance according to 3 empirical antibiotic strategies among adults hospitalized for community-acquired (CA) upper urinary tract infections (UTIs): ceftriaxone (CRO) plus gentamicin (GM) in the intensive care unit (ICU), imipenem (IMP), and individualized choice (IMP or CRO) based on clinical risk factors for CA- extended-spectrum β-lactamase (ESBL).

RESULTS

The estimated prevalence of CA-ESBL on admission was 5% (range, 1.3%-17.6%); 3% and 97% were admitted to the ICU and medical ward (MW), respectively. In the ICU, CRO plus GM was dominated; IMP was cost-effective (incremental cost-effectiveness ratio: €4,400 per life year saved compared with individualized choice). In the MW, IMP had no impact on mortality and was less costly (-€142 per patient vs CRO, -€38 vs individualized choice). The dominance of IMP was consistent in sensitivity analyses. Compared with CRO, colonization by carbapenem-resistant pathogens increased by an odds ratio of 4.5 in the IMP strategy.

CONCLUSION

Among the ICU patients, empirical IMP therapy reduces mortality at an acceptable cost. Among MW patients, individualized choice or CRO is preferred to limit carbapenem resistance at a reasonable cost.

Nosocomial Outbreak of New Delhi Metallo-β-Lactamase-1-Producing Gram-Negative Bacteria in South Africa: A Case-Control Study

OBJECTIVE

New Delhi metallo-β-lactamase (NDM)-producing Gram-negative bacteria have spread globally and pose a significant public health threat. There is a need to better define risk factors and outcomes of NDM-1 clinical infection. We assessed risk factors for nosocomial infection with NDM-1-producers and associated in-hospital mortality.

METHODS

A matched case-control study was conducted during a nosocomial outbreak of NDM-1-producers in an adult intensive care unit (ICU) in South Africa. All patients from whom NDM-1-producers were identified were considered (n=105). Cases included patients admitted during the study period in whom NDM-1 producing Gram-negative bacteria were isolated from clinical specimens collected ≥48 hours after admission, and where surveillance definitions for healthcare-associated infections were met. Controls were matched for age, sex, date of hospital admission and intensive-care admission. Conditional logistic regression was used to identify risk factors for NDM-1 clinical infection and associated in-hospital mortality.

FINDINGS

38 cases and 68 controls were included. Klebsiella pneumoniae was the most common NDM-1-producer (28/38, 74%). Cases had longer mean hospital stays (44.0 vs. 13.3 days; P < 0.001) and ICU stays (32.5 vs. 8.3 days; P < 0.001). Adjusting for co-morbid disease, the in-hospital mortality of cases was significantly higher than controls (55.3% vs. 14.7%; AOR, 11.29; P < 0.001). Higher Charlson co-morbidity index score (5.2 vs. 4.1; AOR, 1.59; P = 0.005), mechanical ventilation days (7.47 vs. 0.94 days; AOR, 1.32; P = 0.003) and piperacillin/tazobactam exposure (11.03 vs. 1.05 doses; AOR, 1.08; P = 0.013) were identified as risk factors on multivariate analysis. Cases had a significantly higher likelihood of in-hospital mortality when the NDM-1-producer was Klebsiella pneumoniae (AOR, 16.57; P = 0.007), or when they had a bloodstream infection (AOR, 8.84; P = 0.041).

CONCLUSION

NDM-1 infection is associated with significant in-hospital mortality. Risk factors for hospital-associated infection include the presence of co-morbid disease, mechanical ventilation and piperacillin/tazobactam exposure.

Risk factors and outcome of infections with Klebsiella pneumoniae carbapenemase-producing K. pneumoniae in kidney transplant recipients

INTRODUCTION

Solid organ transplant recipients are especially susceptible to healthcare-associated infections with Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp-HAIs). The aim of the study was to evaluate risk factors and outcome of these infections in kidney transplant recipients.

METHODS

This was a retrospective cohort of kidney transplant (KTx) recipients between January 2009 and December 2013. Cases were defined as patients who developed KPC-Kp-HAI, confirmed by PCR for bla( KPC) gene after KTx during the study period. We analysed variables related to recipient; induction immunosuppressant therapy; delayed graft function; use of invasive devices; SOFA score on the first day of infection; type of therapy; time from positive culture to appropriate antimicrobial therapy; bacteraemia; and concomitant infection. Outcome measures were the occurrence of KPC-Kp-HAI and 30-day mortality after KPC-Kp-HAI.

RESULTS

A total of 1,101 were submitted to KTx in the period, 21 patients were classified as infected with KPC-Kp. Another ten patients had KPC-Kp-HAI in the period and were transplanted before 2009. Of those 31 patients, 48.4 % showed evidence of prior colonization and 38.7 % had bacteraemia. The most common site of infection was the surgical wound. Risk factors for KPC-Kp-HAI were multi-organ transplantation and the use of a ureteral stent. Eight of the infected patients experienced recurrence of the infection. The 30-day mortality rate was 41.9 %. Survival was significantly lower among the patients with KPC-Kp-HAI (72 vs. 89.1 %; P = 0.002). The only risk factor independently associated with 30-day mortality was an elevated SOFA score on the first day of infection.

CONCLUSIONS

In KTx recipients, the occurrence of KPC-Kp-HAI was related to invasive devices and type of transplant; these infections had a high rate of recurrence and reduced survival after KTx.

Carbapenem-resistant Enterobacteriaceae: a menace to our most vulnerable patients

The emergence of carbapenem-resistant Enterobacteriaceae (CRE) highlights the importance of effective antibiotics to maintain the safety of our health care system. Clinicians will encounter CRE as a cause of difficult-to-treat and often fatal infections in hospitalized patients. We review the mechanisms of carbapenem resistance, the dissemination and clinical impact of these resistant organisms, and challenges to their detection, treatment, and control.

Epidemiological interpretation of studies examining the effect of antibiotic usage on resistance

Bacterial resistance to antibiotics is a growing clinical problem and public health threat. Antibiotic use is a known risk factor for the emergence of antibiotic resistance, but demonstrating the causal link between antibiotic use and resistance is challenging. This review describes different study designs for assessing the association between antibiotic use and resistance and discusses strengths and limitations of each. Approaches to measuring antibiotic use and antibiotic resistance are presented. Important methodological issues such as confounding, establishing temporality, and control group selection are examined.

Carbapenem-resistant Enterobacteriaceae: a review of treatment and outcomes

The emergence of carbapenem resistance in Enterobacteriaceae is an important threat to global health. Reported outcomes of infections with carbapenem-resistant Enterobacteriaceae (CRE) are poor. Very few options remain for the treatment of these virulent organisms. Antibiotics which are currently in use to treat CRE infections include aminoglycosides, polymyxins, tigecycline, fosfomycin, and temocillin. In addition, the role of combination therapy, including carbapenem containing regimens, remains to be defined. There are several important concerns regarding all of these treatment options such as limited efficacy, increasing reports of resistance, and specific toxicities. Data from retrospective studies favor combination therapy over single-agent therapy for the treatment of CRE bloodstream infections. In summary, new antibiotics are greatly needed, as is additional prospective research.

Outbreak of multidrug-resistant CTX-M-15-producing Enterobacter cloacae in a neonatal intensive care unit

Newborns are rarely infected by extended-spectrum β-lactamase (ESBL)-producing members of the Enterobacteriaceae. In a neonatal intensive care unit, 14 newborns were infected or colonized by CTX-M-15-producing Enterobacter cloacae. All seven infected patients had underlying medical conditions, and five of them were treated successfully with meropenem, whilst one untreated patient died. Paediatric infections caused by multidrug-resistant ESBL-producing Enterobacter cloacae constitute a critical clinical and epidemiological issue.

Patient risk factors for outer membrane permeability and KPC-producing carbapenem-resistant Klebsiella pneumoniae isolation: results of a double case-control study

BACKGROUND

In the 1,200-bed university hospital "Umberto I" in Rome, Italy, we observed a dramatic substitution of a precedingly well-documented Klebsiella pneumoniae clone (ST37) with ertapenem resistance by outer membrane permeability modification (Porin-ER-Kp) with a new K. pneumoniae strain expressing carbapenem resistance due to K. pneumoniae carbapenemase production (KPC-CR-Kp). A case-case-control study was carried out to evaluate risk factors for Porin-ER-Kp and KPC-CR-Kp isolation.

METHODS

All patients with hospital-acquired K. pneumoniae isolation between July 2008 and June 2011 were included. Two case groups including patients harbouring KPC-CR-Kp and Porin-ER-Kp were analysed, with a third control group from whom carbapenem-susceptible K. pneumoniae (CS-Kp) were isolated.

RESULTS

Forty-four KPC-CR-Kp cases, 39 Porin-ER-Kp cases and 60 CS-Kp controls were analysed. During the 3-year study, a specific Porin-ER-Kp endemic clone (ST37) was substituted by a new KPC-CR-Kp clone (ST512). Breakthrough bacteraemias occurred in 21 out of 26 KPC-CR-Kp group bloodstream infections (BSIs); nine of these developed during carbapenem therapy and seven with colistin and/or tigecycline therapy. In 13 Porin-ER-Kp BSIs, breakthrough bacteraemias developed in eight patients and four during carbapenem therapy. In the multivariable analysis, KPC-CR-Kp isolates were associated with carbapenems [odds ratio (OR) 7.74; 95 % confidence interval (CI) 1.70-35.2; p < 0.01) and endoscopy (OR 6.71; 95 % CI 1.25-36.0; p < 0.03). Porin-ER-Kp independent risk factors included second-generation cephalosporins (OR 25.7; 95 % CI 3.20-206.8; p < 0.01), carbapenems (OR 19.1; 95 % CI 4.34-83.9; p < 0.001), acute renal failure (OR 7.17; 95 % CI 1.33-38.6; p < 0.03), endoscopy (OR 6.12; 95 % CI 1.46-25.6; p < 0.02) and third-generation cephalosporins (OR 5.3; 95 % CI 1.34-20.9; p < 0.02).

CONCLUSIONS

Porin-ER-Kp strains needed major antimicrobial pressure compared to KPC-CR-Kp to express resistance. KPC-CR-Kp substituted Porin-ER-Kp strains, causing more infections. KPC-CR-Kp breakthrough bacteraemia occurred even under therapy with tigecycline or colistin, underlining that an antibiotic stewardship programme is needed urgently.

Risk factors for KPC-producing Klebsiella pneumoniae enteric colonization upon ICU admission

OBJECTIVES

To identify risk factors for KPC-producing Klebsiella pneumoniae (KPC-Kp) enteric colonization at intensive care unit (ICU) admission. Recently, the emergence and spread of KPC-producing Enterobacteriaceae in healthcare facilities has become an important issue. Understanding the extent of the reservoir in ICUs may be important for targeted intervention.

METHODS

A prospective observational study of all patients (n = 405) admitted to an ICU was conducted during a 22 month period. Rectal samples were taken from each patient within 12-48 h of admission and were inoculated in selective chromogenic agar. K. pneumoniae isolates were characterized by standard methodology. Antibiotic susceptibility testing (agar disc diffusion method), MIC determination (Etest), identification of carbapenemase-producing isolates (Hodge test) and determination of KPC production (boronic acid-imipenem disc test) were performed. The presence of the bla(KPC) gene was confirmed by PCR. Epidemiological data were collected from the ICU computerized database and patient chart reviews.

RESULTS

Upon ICU admission, 52/405 (12.8%) patients were colonized with KPC-Kp that was associated with the following risk factors: previous ICU stay (OR 12.5; 95% CI 1.8-86.8), chronic obstructive pulmonary disease (OR 6.3; 95% CI 1.2-31.9), duration of previous hospitalization (OR 1.3; 95% CI 1.1-1.4), previous use of carbapenems (OR 5.2; 95% CI 1.0-26.2) and previous use of β-lactams/β-lactamase inhibitors (OR 6.7; 95% CI 1.4-32.9). For patients previously hospitalized on peripheral wards the following risk factors were identified: duration of hospitalization prior to ICU admission (OR 1.1; 95% CI 1.1-1.3), number of comorbidities (OR 1.9; 95% CI 1.1-3.5) and number of antimicrobials administered (OR 2.1; 95% CI 1.3-3.3).

CONCLUSIONS

The high prevalence of KPC-Kp enteric carriage in ICU patients at admission dictates the importance of implementation of infection control measures and strict antibiotic policies prior to ICU transfer.

In Vitro Activities of Ertapenem and Imipenem against Clinical Extended Spectrum Beta-Lactamase-Producing Enterobacteriaceae Collected in Military Teaching Hospital Mohammed V of Rabat

Objective. To study the sensitivity level of extended spectrum beta-lactamase-producing Enterobacteriaceae to Carbapenems (Imipenem, Ertapenem) marketed in Morocco and discusses the place of Ertapenem in the treatment of extended spectrum-beta-lactamase-producing. Materials and Methods. A retrospective study of 110 extended spectrum beta-lactamase-producing Enterobacteriaceae. Isolates obtained from blood cultures, superficial and deep pus, and catheters were conducted. The minimum inhibitory concentrations of Imipenem and Ertapenem were done by the E-test. The modified Hodge test was conducted for resistant or intermediate strains. Results. 99.1% of isolates were susceptible to Imipenem. For Ertapenem, 4 were resistant and 4 intermediate. The modified Hodge test was positive for all 08 isolates. A minimum inhibitory concentration comparison of K. pneumoniae, E. cloacae, and E. coli for Imipenem has noted a significant difference between E. cloacae on one hand and E. coli, K. pneumoniae on the other hand (P < 0.01). No significant difference was noted for minimum inhibitory concentration of Ertapenem. Conclusion. Our results confirm in vitro effectiveness of Ertapenem against extended spectrum beta-lactamase-producing Enterobacteriaceae as reported elsewhere. However, the emergence of resistance to Carbapenems revealed by production of carbapenemases in this study confirmed a necessary bacteriological documented infection before using Ertapenem.

Risk factors for developing clinical infection with carbapenem-resistant Klebsiella pneumoniae in hospital patients initially only colonized with carbapenem-resistant K pneumoniae

BACKGROUND

This study examined predictors of carbapenem-resistant Klebsiella pneumoniae (CRKP) colonization and risk factors for the development of CRKP infection in patients initially only colonized with CRKP.

METHODS

A total of 464 patients with CRKP rectal colonization (CRKP-RC) were identified. Two case-control studies were performed, one comparing risk factors for CRKP-RC in patients who did not develop CRKP infection (CRKP-IN) versus patients without CRKP-RC and CRKP-IN, and the other comparing CRKP-RC patients who did not develop CRKP-IN with those who did.

RESULTS

Forty-two of the 464 colonized patients developed CRKP-IN. Multivariate analysis identified the following predictors for CRKP-RC: antibiotic therapy (odds ratio [OR], 5.76; P ≤ .0001), aminopenicillin therapy (OR, 7.753; P = .004), bedridden (OR, 3.09; P = .021), and nursing home residency (OR, 3.09; P = .013). Risk factors for CRKP-IN in initially CRKP-RC-positive patients were previous invasive procedure (OR, 5.737; P = .021), diabetes mellitus (OR, 4.362; P = .017), solid tumor (OR, 3.422; P = .025), tracheostomy (OR, 4.978; P = .042), urinary catheter insertion (OR, 4.696; P = .037), and antipseudomonal penicillin (OR, 23.09; P ≤ .0001).

CONCLUSIONS

We suggest that in patients with CRKP-RC, a strategy for preventing CRKP-IN might include limiting antipseudomonal penicillin and carbapenem use and preventing infections by closely following compliance with infection control bundles.

Risk factors, molecular epidemiology and outcomes of ertapenem-resistant, carbapenem-susceptible Enterobacteriaceae: a case-case-control study

Background

Increasing prevalence of ertapenem-resistant, carbapenem-susceptible Enterobacteriaceae (ERE) in Singapore presents a major therapeutic problem. Our objective was to determine risk factors associated with the acquisition of ERE in hospitalized patients; to assess associated patient outcomes; and to describe the molecular characteristics of ERE.

Methods

A retrospective case-case-control study was conducted in 2009 at a tertiary care hospital. Hospitalized patients with ERE and those with ertapenem-sensitive Enterobacteriaceae (ESE) were compared with a common control group consisting of patients with no prior gram-negative infections. Risk factors analyzed included demographics; co-morbidities; instrumentation and antibiotic exposures. Two parallel multivariate logistic regression models were performed to identify independent variables associated with ERE and ESE acquisition respectively. Clinical outcomes were compared between ERE and ESE patients.

Results

Twenty-nine ERE cases, 29 ESE cases and 87 controls were analyzed. Multivariate logistic regression showed that previous hospitalization (Odds ratio [OR], 10.40; 95% confidence interval [CI], 2.19–49.20) and duration of fluoroquinolones exposure (OR, 1.18 per day increase; 95% CI, 1.05–1.34) were unique independent predictors for acquiring ERE. Duration of 4^th-generation cephalosporin exposure was found to predict for ESE acquisition (OR, 1.63 per day increase; 95% CI, 1.05–2.54). In-hospital mortality rates and clinical response rates were significantly different between ERE and ESE groups, however ERE infection was not a predictor of mortality. ERE isolates were clonally distinct. Ertapenem resistance was likely to be mediated by the presence of extended-spectrum β-lactamases or plasmid-borne AmpC in combination with impermeability due to porin loss and/or efflux pumps.

Conclusion

Prior hospitalization and duration of fluoroquinolone treatment were predictors of ERE acquisition. ERE infections were associated with higher mortality rates and poorer clinical response rates when compared to ESE infections.

Efficacy of ertapenem for treatment of bloodstream infections caused by extended-spectrum-β-lactamase-producing Enterobacteriaceae

Ertapenem is active against extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae organisms but inactive against Pseudomonas aeruginosa and Acinetobacter baumannii. Due to a lack of therapeutic data for ertapenem in the treatment of ESBL bloodstream infections (BSIs), group 2 carbapenems (e.g., imipenem or meropenem) are often preferred for treatment of ESBL-producing Enterobacteriaceae, although their antipseudomonal activity is unnecessary. From 2005 to 2010, 261 patients with ESBL BSIs were analyzed. Outcomes were equivalent between patients treated with ertapenem and those treated with group 2 carbapenems (mortality rates of 6% and 18%, respectively; P = 0.18).

Clinical epidemiology of carbapenem-intermediate or -resistant Enterobacteriaceae

OBJECTIVES

Despite the increasing incidence of carbapenem-intermediate or -resistant Enterobacteriaceae (CIRE), risk factors associated with CIRE infections have not been well defined. This study characterizes factors associated with CIRE among two different source populations.

METHODS

A case-control study was performed at a tertiary care medical centre between January 2005 and December 2009. Cases were adults with a culture-confirmed Enterobacteriaceae infection with reduced susceptibility to meropenem or ertapenem. The CIRE cases were matched 1:1 to patients from two different control series: (i) those with carbapenem-susceptible Enterobacteriaceae (CSE) infections; and (ii) inpatients residing on the same ward within 30 days of CIRE culture date. Logistic regression was used to identify variables independently associated with CIRE among each source population. Restricted multivariate analyses were performed to determine if covariates predictive of CIRE varied by infecting organism or presence of the bla(KPC) gene.

RESULTS

There were 102 cases of CIRE during the study period. The only covariate independently associated with CIRE in all multivariate analyses was the cumulative number of prior antibiotic exposures. Compared with CSE controls, the odds ratios (95% confidence interval) were 1.43 (1.19-1.72), 2.05 (1.70-2.47) and 2.93 (2.43-3.53) for 1, 2 and ≥ 3 antibiotic exposures, respectively. The strength of this association was comparable for the hospitalized control group and analyses stratified by organism and presence of the bla(KPC) gene.

CONCLUSIONS

A patient's cumulative antibiotic exposure history is likely to be more important than any one specific exposure when determining the likelihood of developing a CIRE infection.