Evidence to improve the treatment of infections caused by carbapenem-resistant Gram-negative bacteria

Effect of a national antibiotic stewardship intervention in China targeting carbapenem overuse: An interrupted time-series analysis

OBJECTIVES

To assess trends and patterns of carbapenem use and to evaluate the effects of a nationwide antibiotic stewardship policy to reduce carbapenem overuse.

METHODS

In this quasi-experimental study, using longitudinal data from the national drug procurement database and interrupted time-series analyses with carbapenems as the intervention group and possible carbapenem substitutes as the comparison group, we evaluated the effects of a national stewardship policy on carbapenem consumption and expenditures, by region and types of healthcare institutions.

RESULTS

The carbapenem procurement volume declined by -28.8% (95% CI -35.0 to -22.6) (-334.4 thousand defined daily doses [DDDs] per month), and carbapenem expenditures showed a relative reduction of -38.1% (-43.9 to -32.2). The gap between the use of carbapenems and each drug in the comparison group narrowed after the policy intervention, with an increase in tigecycline use (14.9 thousand DDDs [10.8-18.9]) and a slower decrease in use of certain third-generation cephalosporin combinations (-85.7 [-143.0 to -28.4]), penicillin combinations (-200.9 [-421.4-19.6]), and fourth-generation cephalosporins (-116.9 [-219.8 to -14.0]). Consumption was highest during the pre-policy period, and declines were largest following the intervention in the eastern region (-32.1%, -39.8 to -24.4) and among tertiary hospitals (-266.2 [-339.5 to -192.9] thousand DDDs per month).

CONCLUSION

This population-level drug utilization research represents the first comprehensive evaluation of the effectiveness of China's nationwide carbapenem stewardship. The national policy targeting carbapenem prescribing has led to a sustained reduction in carbapenem use with limited substitution. Effects varied geographically and were concentrated in tertiary and secondary hospitals.

Genomic Insights Into Molecular Characteristics and Phylogenetic Linkage Between the Cases of Carbapenem-Resistant Klebsiella pneumoniae From a Non-tertiary Hospital in China: A Cohort Study

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) strains have been listed as one of the major clinical concerns. Objectives: We investigated CPKP isolates from non-tertiary hospitals to find disseminated clones and analyze extensive phenotypic and genetic diversity in this study. Methods: In this cohort study, a total of 49 CRKP isolates from 3 hospitals in the same region were collected in 2021. The prevalence and antimicrobial susceptibility patterns were analyzed. Clinical data were retrieved from electronic medical record systems. The molecular types, antimicrobial resistance (AMR) profiles, plasmid replicons, and virulence factors were analyzed. The maximum-likelihood phylogenetic tree and transmission networks were constructed using single-nucleotide polymorphisms (SNPs). Results: The median age of patients (N = 49) was 66.0 years, and 85.7% were male. The most common CRKP infection was nosocomial pneumonia (75.5%), followed by bacteremia (10.2%). More than 53% of isolates were resistant to ceftazidime-avibactam (CAZ/AVI). Forty-five isolates were successfully sequenced; the predominant carbapenem-resistant gene was blaKPC-2 (93.3%). The 30-day mortality in our cohort was 24.5%. The most dominant sequence type (ST) was ST11 (60.0%), followed by ST15 (13.3%). Whole genome sequencing (WGS) analysis exhibited dissemination of ST11 strain clones, ST420, and ST15 clones, both within and outside the given hospital. Conclusions: In this surveillance study, several dissemination chains of CRKP were discovered in the hospital and the region, as ST11 was the main epidemic clone. Our findings suggest that effective infection control practices and antimicrobial stewardship are needed in non-tertiary hospitals in China.

Next-Generation Sequencing of Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated from Patients Hospitalized in the University Hospital Facilities

Carbapenem-resistant (CR) Klebsiella pneumoniae represents an urgent worldwide threat. We focused on CR K. pneumoniae in selected facilities of the University Hospital Bratislava (UHB) to investigate sequence types (STs), clonal relatedness, and antimicrobial resistance. Suspected carbapenem-nonsusceptible K. pneumoniae strains were obtained from hospitalized patients. Further examination included carbapenemase confirmation, cgMLST, and quantitative susceptibility testing. Of the total 41 CR K. pneumoniae strains, 26 (63.4%) were determined as ST11 in hospital No. 1; of these ST11, 22 (84.6%) were found in the first internal clinic. Six (14.6%) ST258 and three (7.3%) ST584 occurred in hospital No. 2; the most, i.e., four (66.7%), ST258 were detected in the geriatric clinic. In hospital No. 3, we found two (4.8%) ST584 and one (2.4%) ST258. Of the ST11 set, 24 (92.3%) produced NDM-1. Furthermore, seven (87.5) ST258 and five (100%) ST584 strains generated KPC-2. Antimicrobial resistance was as follows: ertapenem 97.6%, meropenem 63.4%, tigecycline 7.3%, eravacycline 7.3%, and colistin 2.5%. We revealed a presumably epidemiological association of ST11 with transmission, particularly in the first internal clinic of hospital No. 1, while ST258 and ST584 were related to interhospital dissemination between medical facilities No. 2 and No. 3. It is essential to prevent the circulation of these pathogens within and between healthcare facilities.

Challenge in the Discovery of New Drugs: Antimicrobial Peptides against WHO-List of Critical and High-Priority Bacteria

Bacterial resistance has intensified in recent years due to the uncontrolled use of conventional drugs, and new bacterial strains with multiple resistance have been reported. This problem may be solved by using antimicrobial peptides (AMPs), which fulfill their bactericidal activity without developing much bacterial resistance. The rapid interaction between AMPs and the bacterial cell membrane means that the bacteria cannot easily develop resistance mechanisms. In addition, various drugs for clinical use have lost their effect as a conventional treatment; however, the synergistic effect of AMPs with these drugs would help to reactivate and enhance antimicrobial activity. Their efficiency against multi-resistant and extensively resistant bacteria has positioned them as promising molecules to replace or improve conventional drugs. In this review, we examined the importance of antimicrobial peptides and their successful activity against critical and high-priority bacteria published in the WHO list.

Prevalence, risk factors and molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae in patients from Zhejiang, China, 2008-2018

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is emerging as a worldwide public health concern; however, the long-term molecular epidemiological surveillance of clinical CRKP in China is limited. We conducted a retrospective observational study (2008-2018) to assess the prevalence, susceptibility, risk factors and molecular epidemiology of clinical CRKP isolates. We found the prevalence of CRKP increased from 2.5%, 2008 to 15.8%, 2018. CRKP were significantly more frequent among hospitalized patients from ICU, and it was significantly more likely to be isolated from the capital city (Hangzhou) and the patients aged ≥60 years. Additionally, seasons and specimen types were associated with CRKP infections. The main CRKP sequence type (ST) was ST11, and bla _KPC-2 was the most prevalent gene variant. Together these data reveal an increasing incidence and resistance trends among CRKP, especially the ST11-bla _KPC-2-CRKP, in Zhejiang, during 2008-2018. Our findings are important for hospitals to limit its dissemination and optimize antibiotic administration.

Risk Factors for Carbapenem-Resistant Pseudomonas aeruginosa, Zhejiang Province, China

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a public health concern worldwide, but comprehensive analysis of risk factors for CRPA remains limited in China. We conducted a retrospective observational study of carbapenem resistance in 71,880 P. aeruginosa isolates collected in Zhejiang Province during 2015–2017. We analyzed risk factors for CRPA, including the type of clinical specimen; the year, season, and region in which it was collected; patient information, including age, whether they were an outpatient or inpatient, and whether inpatients were in the intensive care unit or general ward; and the level of hospital submitting isolates. We found CRPA was more prevalent among isolates from patients >60 years of age and in inpatients, especially in intensive care units. In addition, specimen types and seasons in which they were collected were associated with higher rates of CRPA. Our findings can help hospitals reduce the spread of P. aeruginosa and optimize antimicrobial drug use.

Colistin Combined With Tigecycline: A Promising Alternative Strategy to Combat Escherichia coli Harboring bla NDM- 5 and mcr-1

Infections due to carbapenem-resistant NDM-producing Escherichia coli represent a major therapeutic challenge, especially in situations of pre-existing colistin resistance. The aim of this study was to investigate combinatorial pharmacodynamics of colistin and tigecycline against E. coli harboring bla_NDM–5 and mcr-1, with possible mechanisms explored as well. Colistin disrupted the bacterial outer-membrane and facilitated tigecycline uptake largely independent of mcr-1 expression, which allowed a potentiation of the tigecycline-colistin combination. A concentration-dependent decrease in colistin MIC and EC₅₀ was observed with increasing tigecycline levels. Clinically relevant concentrations of colistin and tigecycline combination significantly decreased bacterial density of colistin-resistant E. coli by 3.9 to 6.1-log₁₀ cfu/mL over 48 h at both inoculums of 10⁶ and 10⁸ cfu/mL, and were more active than each drug alone (P < 0.01). Importantly, colistin and tigecycline combination therapy was efficacious in the murine thigh infection model at clinically relevant doses, resulting in >2.0-log₁₀cfu/thigh reduction in bacterial density compared to each monotherapy. These data suggest that the use of colistin and tigecycline combination can provide a therapeutic alternative for infection caused by multidrug-resistant E. coli that harbored both bla_NDM–5 and mcr-1.

Evaluation of the MicroScan Colistin Well and Gradient Diffusion Strips for Colistin Susceptibility Testing in Enterobacteriaceae

Many laboratories are unable to perform colistin susceptibility testing. Diffusion-based antimicrobial susceptibility testing methods are not recommended, and not all laboratories have the capacity to perform broth microdilution (BMD). Using a multistep tiered approach, we investigated whether the adapted use of the MicroScan colistin well (4 μg/ml) could enhance laboratory capacity for the detection and subsequent molecular characterization of colistin-resistant Enterobacteriaceae For the MicroScan colistin well, categorical agreement with BMD was 92.7%, and the very major error rate was 10.7%. For gradient diffusion strips, the categorical agreement was 86.4%, and the very major error rate was 53.6%. The MicroScan colistin well detected all isolates carrying mcr-1 or mcr-2 genes (n = 16), but gradient diffusion strips identified an MIC of ≥4 for colistin for only 62.5% of these isolates. A 6-month prospective phenotypic and genotypic study performed at a single clinical microbiology laboratory assessed isolates growing in the MicroScan colistin well for concordance. While 37 of 39 isolates growing in the MicroScan colistin well displayed a colistin MIC of ≥4 by BMD, all were determined to be negative for the mcr-1 and mcr-2 genes by PCR. A retrospective review of all Escherichia coli, Klebsiella spp., and Enterobacter spp. tested by MicroScan at this laboratory in 2016 identified 260 of 7,894 (3.3%) isolates that grew in the MicroScan colistin well. Based on the data presented, clinical and public health laboratories could use the MicroScan colistin well as a first screen for the detection of isolates displaying elevated colistin MICs, which could then undergo further characterization.

Synergy of polymyxin B, tigecycline and meropenem against carbapenem-resistant Enterobacter cloacae complex isolates

Here, we evaluated the combinations of antibiotics polymyxin B (PMB), tigecycline (TGC) and meropenem (MEM) by time-kill curves (TKC) against carbapenem-resistant Enterobacter cloacae isolates. Combination of PMB/TGC and PMB/MEM showed promising results in sub-inhibitory concentration of PMB indicating the possibility of reducing the dose of PMB used in the treatment.

First Description of Colistin and Tigecycline-Resistant Acinetobacter baumannii Producing KPC-3 Carbapenemase in Portugal

Herein, we describe a case report of carbapenem-resistant Acinetobacter baumannii and Klebsiella pneumoniae isolates that were identified from the same patient at a Tertiary University Hospital Centre in Portugal. Antimicrobial susceptibility and the molecular characterization of resistance and virulence determinants were performed. PCR screening identified the presence of the resistance genes bla_KPC-3, bla_TEM-1 and bla_SHV-1 in both isolates. The KPC-3 K. pneumoniae isolate belonged to the ST-14 high risk clone and accumulated an uncommon resistance and virulence profile additional to a horizontal dissemination capacity. In conclusion, the molecular screening led to the first identification of the A. baumannii KPC-3 producer in Portugal with a full antimicrobial resistance profile including tigecycline and colistin.

Effect of increasing meropenem MIC on the killing activity of meropenem in combination with amikacin or polymyxin B against MBL- and KPC-producing Enterobacter cloacae

Carbapenem resistant Enterobacteriaceae (CRE) are a growing threat worldwide. Infections caused by these organisms have exhibited high rates of mortality (50%) for which there is no standard of care and a dearth of clinical trials. Most in vitro data on CRE focus on Klebsiella pneumoniae, but it is known that effective therapy may depend on species or even strain. To address this, meropenem, amikacin, and polymyxin B alone and in combination were evaluated by time kill against four carbapenem-producing Enterobacter cloacae clinical isolates representing a range of meropenem nonsusceptibility (2-32 mg/L) and resistance mechanisms (KPC 2 and/or VIM 1). As meropenem minimum inhibitory concentration (MIC) increased, bactericidal activity and synergy were maintained for 48 hours in isolates exposed to meropenem and amikacin, but synergy and bactericidal activity were not maintained in all isolates exposed to meropenem and polymyxin B.

Antibiotic consumption versus the prevalence of carbapenem-resistant Gram-negative bacteria at a tertiary hospital in China from 2011 to 2017

PURPOSE

China launched a 3-year rectification scheme on the clinical use of antibiotics in 2011, and a specific scheme on carbapenem use in February 2017. This study investigated the trends in and correlations between antibiotic consumption and the prevalence of carbapenem-resistant Gram-negative bacteria (CRGN) at a tertiary hospital during these years, particularly in carbapenem consumption.

METHODS

The data were collected calculated per quarter from 2011 to 2017. The trends in antibiotic consumption and resistance were analyzed by regression analysis, while Spearman correlation analysis was used to assess the correlations.

RESULT

The total consumption of antibiotics halved during the 7-year study period, from 770.15 DDDs/1000 PDs in quarter 1 of 2011 to 395.07 DDDs/1000 PDs in quarter 4 of 2017. Meantime, carbapenem consumption showed the significant increase, from 28.71 DDDs/1000 PDs to 49.2 DDDs/1000 PDs. The detection rates of CRGN (carbapenem-resistant Klebsiella pneumonia, Acinetobacter baumannii, and Pseudomonas aeruginosa) remained stable (P>0.05). The positive correlation was only discovered between the resistance rate of carbapenem-resistant K. pneumonia and the usage of carbapenems, which included meropenem and imipenem, with coefficients of 0.543, 0.537, and 0.497 (P<0.05), respectively. There was no more significant correlation in this study.

CONCLUSION

The total consumption of antibiotics reduced significantly in the analysed hospital, which could be related to the antimicrobial stewardship programme. However, the carbapenem consumption was increased. The specific index should be established to limit the application of carbapenems. This study identified the positive correlation between the detection rate of carbapenem-resistant K. pneumonia and carbapenem consumption. More research is needed to confirm the impact of restricting and appropriated use of carbapenems on the prevalence of CRGN.

Know your enemy: managing resistant Gram-negative infections

Report from the 28th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID 2018), Madrid, Spain, 21-24 April 2018 Gram-negative bacteria such as Klebsiella, Acinetobacter and Pseudomonas cause some of the most serious infections and are increasingly resistant to multiple drugs and in some cases, to all available antibiotics. Management of infections caused by these organisms is a global challenge that has serious implications for every hospital and department and therefore every delegate attending ECCMID 2018.