Molecular characteristics of carbapenem-resistant Pseudomonas aeruginosa isolated from urine in Hyogo, Japan

Treatment of carbapenem-resistant Pseudomonas aeruginosa infections: a case for cefiderocol

INTRODUCTION

Carbapenem-resistant (CR) Pseudomonas aeruginosa infections constitute a serious clinical threat globally. Patients are often critically ill and/or immunocompromised. Antibiotic options are limited and are currently centered on beta-lactam-beta-lactamase inhibitor (BL-BLI) combinations and the siderophore cephalosporin cefiderocol.

AREAS COVERED

This article reviews the mechanisms of P. aeruginosa resistance and their potential impact on the activity of current treatment options, along with evidence for the clinical efficacy of BL-BLI combinations in P. aeruginosa infections, some of which specifically target infections due to CR organisms. The preclinical and clinical evidence supporting cefiderocol as a treatment option for P. aeruginosa involving infections is also reviewed.

EXPERT OPINION

Cefiderocol is active against most known P. aeruginosa mechanisms mediating carbapenem resistance. It is stable against different serine- and metallo-beta-lactamases, and, due to its iron channel-dependent uptake mechanism, is not impacted by porin channel loss. Furthermore, the periplasmic level of cefiderocol is not affected by upregulated efflux pumps. The potential for on-treatment resistance development currently appears to be low, although more clinical data are required. Information from surveillance programs, real-world compassionate use, and clinical studies demonstrate that cefiderocol is an important treatment option for CR P. aeruginosa infections.

Phenotypic and genotypic within-host diversity of Pseudomonas aeruginosa urinary isolates

This study aimed to assess phenotypic and molecular inter-patient and within-host diversity of Pseudomonas aeruginosa isolates responsible for urinary tract infection (UTI) or asymptomatic bacteriuria (AB). Clinical data of 120 consecutive P. aeruginosa UTI (n = 40) and AB (n = 80) were prospectively analyzed. Up to five P. aeruginosa isolates per sample were collected. Antimicrobial susceptibility testing (AST) was determined for all isolates (n = 591); a subset of 358 was characterized by multilocus sequence typing. 444 isolates (75%) were non-multidrug resistant (MDR), 113 (19%) were MDR, and 34 (6%) were extensively drug resistant. A genetically highly diverse population was observed (64 sequence types [STs]), without strict correlation between genotypes and clinical settings. 35 patients (28%; 12 UTIs and 23 ABs) presented distinct antimicrobial resistance (AMR) profiles within a given urine sample, significantly associated with previous carbapenem and fluroquinolones exposure; five of them also exhibited polyclonal UTI or AB (with isolates belonging to two STs). P. aeruginosa urinary isolates of these 120 patients were highly diverse, in terms of AMR as well as genetic background. Both within-host AMR and molecular diversity can complicate AST, treatment and control of P. aeruginosa UTI.

Epidemiology, Molecular Characteristics, and Virulence Factors of Carbapenem-Resistant Pseudomonas aeruginosa Isolated from Patients with Urinary Tract Infections

Purpose

Pseudomonas aeruginosa is an important pathogen that causes urinary tract infections. Carbapenems are the drugs of choice for the treatment of P. aeruginosa infections. However, the emergence and spread of carbapenem-resistant P. aeruginosa (CRPA) is a serious global health threat. In this study, we investigated the epidemiology, molecular characteristics, drug resistance, and virulence factors of CRPA isolated from urine samples.

Methods

A total of 124 P. aeruginosa isolates were obtained from urine samples collected between March 2020 and February 2021. Clonal relatedness was evaluated using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). We performed antimicrobial susceptibility tests and investigated the presence of carbapenemase genes and virulence factors in CRPA isolates.

Results

The carbapenem resistance rate of the isolated P. aeruginosa was 46.7% (59/124). A total of 54 (91.5%) out of the 59 CRPA isolates were identified as multidrug-resistant. The majority of the CRPA isolates (81.4%, 48/59) harbored carbapenemase genes, such as bla_IMP-6 or bla_NDM-1. In an epidemiological analysis using MLST, 88.1% of CRPA isolates were confirmed to be ST773 (50.8%, 30/59) or ST235 (37.3%, 22/59). The CRPA isolates harboring bla_IMP-6 and bla_NDM-1 belonged to ST235 (PFGE pulsotypes E1-E18, F) and ST773 (PFGE pulsotypes H1-H2, I1-I16) subtypes, respectively. The studied CRPA isolates simultaneously harbored 10 to 14 virulence factors of the 16 virulence factors examined. Nine virulence factor genes (toxA, exoT, plcH, plcN, phzM, phzS, lasB, aprA, and algD) were identified in all CRPA isolates.

Conclusion

Our study shows that P. aeruginosa ST235 harboring bla_IMP-6 and ST773 harboring bla_NDM-1—known internationally as high-risk clones with multiple virulence factors—are widely spread in the study area. These findings suggest that continuous monitoring is necessary to prevent the further spread of carbapenemase-producing CRPA.

Burden of illness in US hospitals due to carbapenem-resistant Gram-negative urinary tract infections in patients with or without bacteraemia

Background

Urinary tract infections (UTIs) are the most common infections caused by Gram-negative bacteria and represent a major healthcare burden. Carbapenem-resistant (CR) strains of Enterobacterales and non-lactose fermenting pathogens further complicate treatment approaches.

Methods

We conducted a retrospective analysis of the US Premier Healthcare Database (2014–2019) in hospitalised adults with a UTI to estimate the healthcare burden of Gram-negative CR UTIs among patients with or without concurrent bacteraemia.

Results

Among the 47,496 patients with UTI analysed, CR infections were present in 2076 (4.4%). Bacteraemia was present in 24.5% of all UTI patients, and 1.7% of these were caused by a CR pathogen. The most frequent CR pathogens were Pseudomonas aeruginosa (49.4%) and Klebsiella pneumoniae (14.2%). Patients with CR infections had a significantly longer hospital length of stay (LOS) (median [range] 8 [5–12] days vs 6 [4–10] days, P < 0.001), were less likely to be discharged home (38.4% vs 51.0%, P < 0.001), had a higher readmission rate (22.6% vs 13.5%, P < 0.001), and had greater LOS-associated charges (mean US$ 91,752 vs US$ 66,011, P < 0.001) than patients with carbapenem-susceptible (CS) infections, respectively. The impact of CR pathogens was greater in patients with bacteraemia (or urosepsis) and these CR urosepsis patients had a significantly higher rate of mortality than those with CS urosepsis (10.5% vs 6.0%, P < 0.001).

Conclusions

Among hospitalised patients with UTIs, the presence of a CR organism and bacteraemia increased the burden of disease, with worse outcomes and higher hospitalisation charges than disease associated with CS pathogens and those without bacteraemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06229-x.

Evaluation of MBT STAR-Cepha and MBT STAR-Carba kits for the detection of extended-spectrum β-lactamases and carbapenemase producing microorganisms using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Rapid and simple detection of extended-spectrum β-lactamase (ESBL) and carbapenemase is essential for antimicrobial treatment and infection control. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based MBT STAR-Cepha and MBT STAR-Carba kits have been developed with simplified MBT STAR-BL operations. However, the utility of these kits has not been fully examined in clinical microbiology laboratories. In this study, we evaluated the utility of MALDI-TOF MS-based MBT STAR-Cepha and MBT STAR-Carba kits to detect ESBL and carbapenemase-producing bacteria, and compared it with the conventional broth microdilution test and PCR amplification assay. We found that the MBT STAR-Cepha kit efficiently distinguished resistant strains of third-generation cephalosporin susceptibility phenotypes and non-SHV-type ESBL producers. In the receiver operating characteristic analysis, the area under the receiver operating characteristic curve (AUC) for detecting third-generation cephalosporin resistance using the MBT STAR-Cepha kit was 0.97-1.00, but the AUC for detecting ESBL producers was 0.64. In addition, we showed that the MBT STAR-Carba kit enabled the accurate detection of antimicrobial resistance by IMP-type carbapenemase producers. The AUC for detecting carbapenemase producers was 1.00. The results suggested that the target bacterial strains, antimicrobial susceptibility phenotypes, and resistance genes were important for the utility of the MALDI-TOF MS-based MBT STAR-Cepha and MBT STAR-Carba kits in bacterial routine diagnostics.

Carbapenemase-Producing Non-Glucose-Fermenting Gram-Negative Bacilli in Africa, Pseudomonas aeruginosa and Acinetobacter baumannii: A Systematic Review and Meta-Analysis

Background

Studies have reported that the existence of CP bacteria in Africa, but, in general, comprehensive data about the molecular epidemiology of CP organisms are limited. Therefore, this systematic review and meta-analysis expound the pooled prevalence of CP P. aeruginosa and CP A. baumannii clinical isolates in Africa. It also identified the diversity of carbapenemases or their encoding genes among the isolates in Africa. Lastly, the review observed the trends of these CP isolates in Africa.

Methods

A comprehensive search was performed between July 2019 and October 2019 in the following databases: PubMed, Google Scholar, and African Journal online. The included articles were published only in English. The screening was done by two authors independently. The data extracted on Excel spreadsheet were transferred to STATA 11 software for analysis.

Results

From a total of 1,454 articles searched, 42 articles were eligible. Most of the studies were conducted in the North Africa region. But there was no report from Central Africa. The pooled prevalence of CP P. aeruginosa and CP A. baumannii among the clinical specimens in Africa was 21.36% and 56.97%, respectively. OXA-23 and VIM were the most prevailing carbapenemase among P. aeruginosa and A. baumannii, respectively. The cumulative meta-analysis revealed a relative increment of the prevalence of CP P. aeruginosa over time in Africa but it showed a higher prevalence of CP A. baumannii isolates across years.

Conclusion

The review revealed a high pooled prevalence of CP A. baumannii clinical isolates in Africa which needs urgent action. Moreover, the emergence of concomitant carbapenemases, especially OXA-23 +  NDM among CP A. baumannii, was also an alarming problem.

Characterize carbapenem-resistant Klebsiella pneumoniae isolates for nosocomial pneumonia and their Gram-negative bacteria neighbors in the respiratory tract

This study was conducted to perform an epidemiological survey of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates for nosocomial pneumonia (NP) and visit their Gram-negative bacteria neighbors (GNNs) from the respiratory tracts. Pulsed-field gel electrophoresis and multi locus sequence typing were performed to evaluate the clonal relationships of these isolates. Statistical methods were then used to understand their possible relationship between CRKP and their GNNs. Among the 63 CRKP isolates, 84.1% produced a KPC-2 carbapenemase gene, followed by blaNDM-1 and blaIMP-38 like. 13 different STs and 29 clones were identified. Less heterogeneous clone backgrounds were observed in 53 KPC-2 K. pneumoniae isolates, and 6 STs have been found to contain KPC-2, of which the predominant ST11 harbored 47 KPC-2-producing K. pneumoniae isolates. Particularly, the two infrequent isolates co-possessing blaKPC-2 and blaIMP-38 like shared a different clonal relationship. 87 GNNs isolates of CRKP were established, the analysis present that different strains showed significant or no difference with CRKP upon antibiotics susceptibility. Conclusion, ST11 harboring KPC-2-producing K. pneumoniae isolates were dominant for NP, and both clonal spread and horizontal transfer contributed to the dissemination of CRKP. However, additional studies are needed to explore the biological relationship with their GNNs.