Geographic Patterns of Carbapenem-resistant Pseudomonas aeruginosa in the Asia-Pacific Region: Results from the Antimicrobial Testing Leadership and Surveillance (ATLAS) program, 2015-2019

Unveiling the impact: COVID-19's influence on bacterial resistance in the Kingdom of Bahrain

BACKGROUND

Antibiotic resistance is a growing global health threat, and understanding local trends in bacterial isolates and their susceptibility patterns is crucial for effective infection control and antimicrobial stewardship. The coronavirus disease 2019 (COVID-19) pandemic has introduced additional complexities, potentially influencing these patterns.

AIM

To analyze trends in bacterial isolates and their antibiotic susceptibility patterns at Salmaniya Medical Complex from 2018 to 2023, with a specific focus on the impact of the COVID-19 pandemic on these trends.

METHODS

A retrospective analysis of microbiological data was conducted, covering the period from 2018 to 2023. The study included key bacterial pathogens such as Escherichia coli (E. coli), Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus, among others. The antibiotic susceptibility profiles of these isolates were assessed using standard laboratory methods. To contextualize the findings, the findings were compared with similar studies from other regions, including China, India, Romania, Saudi Arabia, the United Arab Emirates, Malaysia, and United States.

RESULTS

The study revealed fluctuating trends in the prevalence of bacterial isolates, with notable changes during the COVID-19 pandemic. For example, a significant increase in the prevalence of Staphylococcus aureus was observed during the pandemic years, while the prevalence of E. coli showed a more variable pattern. Antibiotic resistance rates varied among the different pathogens, with a concerning rise in resistance to commonly used antibiotics, particularly among Klebsiella pneumoniae and E. coli. Additionally, the study identified an alarming increase in the prevalence of multidrug-resistant (MDR) strains, especially within Klebsiella pneumoniae and E. coli isolates. The impact of the COVID-19 pandemic on these trends was evident, with shifts in the frequency, resistance patterns, and the emergence of MDR bacteria among several key pathogens.

CONCLUSION

This study highlights the dynamic nature of bacterial isolates and their antibiotic susceptibility patterns at Salmaniya Medical Complex, particularly in the context of the COVID-19 pandemic. The findings underscore the need for continuous monitoring and effective anti-microbial stewardship programs to combat the evolving threat of antibiotic resistance. Further research and policy initiatives are required to address the identified challenges and improve patient outcomes in the face of these ongoing challenges.

In vivo divergent evolution of cross-resistance to new β-lactam/β-lactamase inhibitor combinations in Pseudomonas aeruginosa following ceftazidime/avibactam treatment

PURPOSE

To describe and characterize the evolutionary process of cross-resistance to ceftazidime/avibactam, ceftolozane/tazobactam and imipenem/relebactam of a carbapenem-resistant Pseudomonas aeruginosa (CRPA) lineage isolated from a patient receiving two courses of ceftazidime/avibactam treatment.

METHODS

The minimum inhibitory concentrations (MICs) of strains were determined by broth microdilution methods. The mutant genes were identified by the whole genome sequencing results. Cloning, knockout and complementation experiments were used to evaluate the impact of the resistance relative genes on the MICs. Reverse transcription-quantitative PCR was used to evaluate the relative expression of ampC and mexA. The fitness cost was measured by growth curve tests.

RESULTS

A total of 24 CRPA strains were isolated encompassing the whole ceftazidime/avibactam treatment. The CRPA strains developed high-level resistance to ceftazidime/avibactam and cross-resistance to ceftolozane/tazobactam or imipenem/relebactam, clustering into clade A and clade B, respectively. In both clades, the overexpression of AmpC was crucial to ceftazidime/avibactam resistance, which was driven by AmpD deficiency in clade A and dacB mutation in clade B, respectively. In clade A, mraY mutation and a new allele of AmpC (blaPDC-575) elevated resistance to ceftazidime/avibactam, with blaPDC-575 also conferring resistance to ceftolozane/tazobactam. In clade B, mexB mutation was associated with the resistance to both ceftazidime/avibactam and imipenem/relebactam. Moreover, the fitness costs of P. aeruginosa strains typically increased with the higher MICs of ceftazidime/avibactam.

CONCLUSION

Divergent resistance evolution resulted in a complex phenotype in the CRPA lineage, posing significant challenge to clinical treatment. The resistance surveillance needs to be prioritized, and new therapeutic strategies are urgently required.

Navigating the Current Treatment Landscape of Metallo-β-Lactamase-Producing Gram-Negative Infections: What are the Limitations?

The spread of carbapenemase-producing gram-negative pathogens, especially those producing metallo-β-lactamases (MBLs), has become a major health concern. MBLs are molecularly the most diverse carbapenemases, produced by a wide spectrum of gram-negative organisms, including the Enterobacterales, Pseudomonas spp., Acinetobacter baumannii, and Stenotrophomonas maltophilia, and can hydrolyze most β-lactams using metal ion cofactors in their active sites. Over the years, the prevalence of MBL-carrying isolates has increased globally, particularly in Asia. MBL infections are associated with adverse clinical outcomes including longer length of hospital stay, ICU admission, and increased mortality across the globe. The optimal treatment for MBL infections not only depends on the pathogen but also on the underlying resistance mechanisms. Currently, there are only few drugs or drug combinations that can efficiently offset MBL-mediated resistance, which makes the treatment of MBL infections challenging. The rising concern of MBLs along with the limited treatment options has led to the need and development of drugs that are specifically targeted towards MBLs. This review discusses the prevalence of MBLs, their clinical impact, and the current treatment options for MBL infections and their limitations. Furthermore, this review will discuss agents currently in the pipeline for treatment of MBL infections.

Antimicrobial Resistance Profiles of Pseudomonas aeruginosa in the Arabian Gulf Region Over a 12-Year Period (2010-2021)

OBJECTIVES

To evaluate literature from a 12-year period (2010-2021) on the antimicrobial resistance profile of Pseudomonas aeruginosa from the Arabian Gulf countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates).

METHODS

An electronic literature search was conducted for articles on antimicrobial resistance in P. aeruginosa and associated phenotypes, covering the period of 1st January 2010 to 1st December 2021.

RESULTS

Antimicrobial resistance in the Arabian Gulf was highest to meropenem (10.3-45.7%) and lowest to colistin (0.0-0.8%), among the agents tested. Annual data showed that ceftazidime resistance (Kuwait), piperacillin-tazobactam non-susceptibility (Qatar), and aztreonam, imipenem, and meropenem resistance (Saudi Arabia) increased by 12-17%. Multiple mechanisms of carbapenem resistance were identified and multiple clones were detected, including high-risk clones such as ST235. The most common carbapenemases detected were the VIM-type metallo-β-lactamases.

CONCLUSIONS

Among P. aeruginosa in the Arabian Gulf countries, resistance to meropenem was higher than to the other agents tested, and meropenem resistance increased in Saudi Arabia during the study period. Resistance to colistin, a classic antibiotic used to treat Pseudomonas spp. infections, remained low. The VIM-type β-lactamase genes were dominant. We recommend local and regional antimicrobial resistance surveillance programs to detect the emergence of resistance genes and to monitor antimicrobial resistance trends in P. aeruginosa.

Tracing the origin of NDM-1-producing and extensively drug-resistant Pseudomonas aeruginosa ST357 in the Netherlands

BACKGROUND

In the hospital environment, carbapenemase-producing Pseudomonas aeruginosa (CPPA) may lead to fatal patient infections. However, the transmission routes of CPPA often remain unknown. Therefore, this case study aimed to trace the origin of CPPA ST357, which caused a hospital-acquired pneumonia in a repatriated critically ill patient suffering from Guillain-Barré Syndrome in 2023.

METHODS

Antimicrobial susceptibility of the CPPA isolate for 30 single and combination therapies was determined by disk-diffusion, Etest or broth microdilution. Whole-genome sequencing was performed for three case CPPA isolates (one patient and two sinks) and four distinct CPPA ST357 patient isolates received in the Dutch CPPA surveillance program. Furthermore, 193 international P. aeruginosa ST357 assemblies were collected via three genome repositories and analyzed using whole-genome multi-locus sequence typing in combination with antimicrobial resistance gene (ARG) characterization.

RESULTS

A Dutch patient who carried NDM-1-producing CPPA was transferred from Kenya to the Netherlands, with subsequent dissemination of CPPA isolates to the local sinks within a month after admission. The CPPA case isolates presented an extensively drug-resistant phenotype, with susceptibility only for colistin and cefiderocol-fosfomycin. Phylogenetic analysis showed considerable variation in allelic distances (mean = 150, max = 527 alleles) among the ST357 isolates from Asia (n = 92), Europe (n = 58), Africa (n = 21), America (n = 16), Oceania (n = 2) and unregistered regions (n = 4). However, the case isolates (n = 3) and additional Dutch patient surveillance program isolates (n = 2) were located in a sub-clade of isolates from Kenya (n = 17; varying 15-49 alleles), the United States (n = 7; 21-115 alleles) and other countries (n = 6; 14-121 alleles). This was consistent with previous hospitalization in Kenya of 2/3 Dutch patients. Additionally, over half of the isolates (20/35) in this sub-clade presented an identical resistome with 9/17 Kenyan, 5/5 Dutch, 4/7 United States and 2/6 other countries, which were characterized by the blaNDM-1, aph(3')-VI, ARR-3 and cmlA1 ARGs.

CONCLUSION

This study presents an extensively-drug resistant subclone of NDM-producing P. aeruginosa ST357 with a unique resistome which was introduced to the Netherlands via repatriation of critically ill patients from Kenya. Therefore, the monitoring of repatriated patients for CPPA in conjunction with vigilance for the risk of environmental contamination is advisable to detect and prevent further dissemination.

Evaluation of MMV Pandemic Response Box compounds to identify potent compounds against clinically relevant bacterial and fungal clinical isolates in vitro

Background

Multidrug resistant bacterial and fungal pathogens are resistant to a number of significant front-line drugs, hence, identification of new inhibitory agents to combat them is crucial. In this study, we aim to evaluate the activity of Pandemic Box compounds from Malaria Medicines Venture (MMV) against A. baumannii and P. aeruginosa bacterial, C. auris, C. albicans and A. niger fungal clinical isolates.

Methods

Isolates were initially screened with 201 antibacterial and 46 antifungal compounds (10 μM) using a microbroth dilution in triplicates to determine MIC. A persister assay was performed for bacterial pathogens.

Results

Out of 201 antibacterial compounds, twenty-nine and seven compounds inhibited the growth of A. baumannii and P. aeruginosa at 10 μM, respectively. MMV1580854, MMV1579788, eravacycline and epetraborole inhibited both the bacterial test isolates. In a persister assay, MMV1634390 showed complete bactericidal effect against A. baumannii. With antifungal activity compounds, C. auris responded to15 compounds, Six compounds inhibited C. albicans and one was effective against A. niger at 10 μM. The ratio of Minimum Fungicidal Concentration (MFC): Minimum Inhibitory Concentration (MIC) of MMV1782110 was 2 against C. auris. Eberconazole, amorolfine and luliconazole are fungicidal targeting C. albicans at a MFC: MIC ratio of 2.

Conclusion

Five compounds from MMV Pandemic Box were found to be inhibiting colistin and ceftazidime resistant A. baumannii clinical isolate, also against colistin and β-lactam resistant P. aeruginosa clinical isolate. MMV1634390 showed complete bactericidal effect against A. baumannii in a persister assay. MMV1782110, Eberconazole, amorolfine and luliconazole exhibited potent anti-fungal activity. Further investigations are warranted to identify the targets and mechanism.

Hospital and municipal wastewater as a source of carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa in the environment: a review

The increase in the prevalence of carbapenem-resistant Gram-negative bacteria, in particular Acinetobacter baumannii (CRAB) and Pseudomonas aeruginosa (CRPA), poses a serious threat for public health worldwide. This article reviews the alarming data on the prevalence of infections caused by CRAB and CRPA pathogens and their presence in hospital and municipal wastewater, and it highlights the environmental impact of antibiotic resistance. The article describes the key role of antibiotic resistance genes (ARGs) in the acquisition of carbapenem resistance and sheds light on bacterial resistance mechanisms. The main emphasis was placed on the transfer of ARGs not only in the clinical setting, but also in the environment, including water, soil, and food. The aim of this review was to expand our understanding of the global health risks associated with CRAB and CRPA in hospital and municipal wastewater and to analyze the spread of these micropollutants in the environment. A review of the literature published in the last decade will direct research on carbapenem-resistant pathogens, support the implementation of effective preventive measures and interventions, and contribute to the development of improved strategies for managing this problem.

Nationwide genome surveillance of carbapenem-resistant Pseudomonas aeruginosa in Japan

Japan is a country with an approximate 10% prevalence rate of carbapenem-resistant Pseudomonas aeruginosa (CRPA). Currently, a comprehensive overview of the genotype and phenotype patterns of CRPA in Japan is lacking. Herein, we conducted genome sequencing and quantitative antimicrobial susceptibility testing for 382 meropenem-resistant CRPA isolates that were collected from 78 hospitals across Japan from 2019 to 2020. CRPA exhibited susceptibility rates of 52.9%, 26.4%, and 88.0% against piperacillin-tazobactam, ciprofloxacin, and amikacin, respectively, whereas 27.7% of CRPA isolates was classified as difficult-to-treat resistance P. aeruginosa. Of the 148 sequence types detected, ST274 (9.7%) was predominant, followed by ST235 (7.6%). The proportion of urine isolates in ST235 was higher than that in other STs (P = 0.0056, χ2 test). Only 4.1% of CRPA isolates carried the carbapenemase genes: blaGES (2) and blaIMP (13). One ST235 isolate carried the novel blaIMP variant blaIMP-98 in the chromosome. Regarding chromosomal mutations, 87.1% of CRPA isolates possessed inactivating or other resistance mutations in oprD, and 28.8% showed mutations in the regulatory genes (mexR, nalC, and nalD) for the MexAB-OprM efflux pump. Additionally, 4.7% of CRPA isolates carried a resistance mutation in the PBP3-encoding gene ftsI. The findings from this study and other surveillance studies collectively demonstrate that CRPA exhibits marked genetic diversity and that its multidrug resistance in Japan is less prevailed than in other regions. This study contributes a valuable data set that addresses a gap in genotype/phenotype information regarding CRPA in the Asia-Pacific region, where the epidemiological background markedly differs between regions.

Risk Factors and Clinical Characteristics of Pandrug-Resistant Pseudomonas aeruginosa

The emergence of increasingly resistant strains of Pseudomonas aeruginosa is a great public health concern. Understanding the risk factors and clinical characteristics of patients with pandrug-resistant P. aeruginosa (PDR-PA) can help inform clinicians in creating guidelines for both prevention and management. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, this scoping review retrieved existing literature on PDR-PA by searching PubMed, SCOPUS, Embase, Web of Science, and CINAHL databases. From the 21 studies that satisfied the inclusion criteria,1,059 P. aeruginosa samples were identified, and 161, or 15.2% of the isolates were found to have pandrug resistance. Furthermore, our review suggests that PDR-PA was largely hospital-acquired, and patients suffering from burn injuries and chronic lung diseases had a higher risk of colonization than other hospitalized individuals. In five out of the 21 studies, administration of the antibiotic colistin emerged to be the preferred therapeutic strategy. With regards to concurrent infections, Acinetobacter and Klebsiella species were found to occur most frequently with PDR-PA, suggesting mutualistic interactions that enable further antimicrobial resistance. In conclusion, this review showed the prevalence of PDR-PA and outlined the demographic and clinical profile of affected patients. Further research is needed to investigate the transmission and outcomes of PDR-PA infections and to find potential therapeutic strategies.

Susceptibility of gram-negative isolates collected in Taiwan to imipenem/relebactam and comparator agents - SMART 2018-2021

BACKGROUND

Imipenem/relebactam (IMR) was approved for patient use in Taiwan in 2023. We evaluated the in vitro susceptibility of recent Gram-negative pathogens collected in Taiwan hospitals to IMR and comparators with a focus on carbapenem-resistant and KPC-carrying non-Morganellaceae Enterobacterales (NME), and carbapenem-resistant Pseudomonas aeruginosa (CRPA).

METHODS

From 2018 to 2021, eight hospitals in Taiwan each collected up to 250 consecutive, aerobic or facultative, Gram-negative pathogens per year from patients with bloodstream, intraabdominal, lower respiratory tract, and urinary tract infections. MICs were determined using Clinical Laboratory Standards Institute (CLSI) broth microdilution. Most isolates that were IMR-, imipenem-, or ceftolozane/tazobactam-nonsusceptible were screened for β-lactamase genes by PCR or whole-genome sequencing.

RESULTS

Ninety-eight percent of NME (n = 5063) and 94% of P. aeruginosa (n = 1518) isolates were IMR-susceptible. Percent susceptible values for non-carbapenem β-lactam comparators, including piperacillin/tazobactam, were 68-79% for NME isolates, while percent susceptible values for all β-lactam comparators, including meropenem, were 73-81% for P. aeruginosa. IMR retained activity against 93% of multidrug-resistant (MDR) NME and 70% of MDR P. aeruginosa. Sixty-five percent of carbapenem-resistant NME and 81% of KPC-positive NME (n = 80) were IMR-susceptible. IMR inhibited 70% of CRPA (n = 287). Fifty percent of IMR-nonsusceptible NME tested for β-lactamase carriage had an MBL or OXA-48-like enzyme, whereas most (95%) IMR-nonsusceptible P. aeruginosa examined did not carry acquired β-lactamase genes.

CONCLUSION

Based on our in vitro data, IMR may be a useful option for the treatment of hospitalized patients in Taiwan with infections caused by common Gram-negative pathogens, including carbapenem-resistant NME, KPC-positive NME, and CRPA.

Molecular Analysis of Carbapenem and Aminoglycoside Resistance Genes in Carbapenem-Resistant Pseudomonas aeruginosa Clinical Strains: A Challenge for Tertiary Care Hospitals

Carbapenem-resistant Pseudomonas aeruginosa (P. aeruginosa) strains have become a global threat due to their remarkable capability to survive and disseminate successfully by the acquisition of resistance genes. As a result, the treatment strategies have been severely compromised. Due to the insufficient available data regarding P. aeruginosa resistance from Pakistan, we aimed to investigate the resistance mechanisms of 249 P. aeruginosa strains by antimicrobial susceptibility testing, polymerase chain reaction for the detection of carbapenemases, aminoglycoside resistance genes, extended-spectrum beta-lactamases (ESBLs), sequence typing and plasmid typing. Furthermore, we tested silver nanoparticles (AgNPs) to evaluate their in vitro sensitivity against antimicrobial-resistant P. aeruginosa strains. We observed higher resistance against antimicrobials in the general surgery ward, general medicine ward and wound samples. Phenotypic carbapenemase-producer strains comprised 80.7% (201/249) with 89.0% (179/201) demonstrating genes encoding carbapenemases: blaNDM-1 (32.96%), blaOXA48 (37.43%), blaIMP (7.26%), blaVIM (5.03%), blaKPC-2 (1.12%), blaNDM-1/blaOXA48 (13.97%), blaOXA-48/blaVIM (1.68%) and blaVIM/blaIMP (0.56%). Aminoglycoside-modifying enzyme genes and 16S rRNA methylase variants were detected in 43.8% (109/249) strains: aac(6')-lb (12.8%), aac(3)-lla (12.0%), rmtB (21.1%), rmtC (11.0%), armA (12.8%), rmtD (4.6%), rmtF (6.4%), rmtB/aac(3)-lla (8.2%), rmtB/aac(6')-lla (7.3%) and rmtB/armA (3.6%). In total, 43.0% (77/179) of the strains coharbored carbapenemases and aminoglycoside resistance genes with 83.1% resistant to at least 1 agent in 3 or more classes and 16.9% resistant to every class of antimicrobials tested. Thirteen sequence types (STs) were identified: ST235, ST277, ST234, ST170, ST381, ST175, ST1455, ST1963, ST313, ST207, ST664, ST357 and ST348. Plasmid replicon types IncFI, IncFII, IncA/C, IncL/M, IncN, IncX, IncR and IncFIIK and MOB types F11, F12, H121, P131 and P3 were detected. Meropenem/AgNPs and Amikacin/AgNPs showed enhanced antibacterial activity. We reported the coexistence of carbapenemases and aminoglycoside resistance genes among carbapenem-resistant P. aeruginosa with diverse clonal lineages from Pakistan. Furthermore, we highlighted AgNP's potential role in handling future antimicrobial resistance concerns.

Susceptibility of Gram-negative isolates collected in South Korea to imipenem/relebactam and comparator agents-SMART 2018-21

Objectives

To evaluate the in vitro susceptibility of recent Gram-negative pathogens collected in South Korean medical centres to imipenem/relebactam and comparator agents.

Methods

From 2018 to 2021, six hospitals in South Korea each collected up to 250 consecutive, aerobic or facultative Gram-negative pathogens per year from patients with bloodstream, intra-abdominal, lower respiratory tract and urinary tract infections. MICs were determined using CLSI broth microdilution and interpreted by 2023 CLSI breakpoints. Most isolates that were imipenem/relebactam, imipenem or ceftolozane/tazobactam non-susceptible were screened for β-lactamase genes by PCR or WGS.

Results

Of all non-Morganellaceae Enterobacterales (NME) isolates (n = 4100), 98.8% were imipenem/relebactam susceptible. Most NME were also susceptible to imipenem alone (94.7%) and meropenem (97.3%); percent susceptible values for non-carbapenem β-lactam comparators were lower (68%-80%). Imipenem/relebactam retained activity against 96.4%, 70.8% and 70.6% of MDR, difficult-to-treat resistant (DTR) and meropenem-non-susceptible NME, respectively, and inhibited 93.1% of KPC-carrying and 95.5% of ESBL-carrying NME. Of imipenem/relebactam-resistant NME, 21/25 (84.0%) carried an MBL or an OXA-48-like carbapenemase. Of all Pseudomonas aeruginosa isolates (n = 738), 82.8% were imipenem/relebactam susceptible; percent susceptible values for all β-lactam comparators, including carbapenems (imipenem, meropenem) were 61.5%-74.7%. Less than 20% of MDR and DTR isolates, and 41% of meropenem-non-susceptible P. aeruginosa isolates were imipenem/relebactam susceptible. Of imipenem/relebactam-resistant P. aeruginosa isolates, 61.6% carried an MBL and 37.0% did not possess any acquired β-lactamase genes.

Conclusions

Based on in vitro data, imipenem/relebactam, if licensed in South Korea, may be a viable treatment option for many hospitalized patients infected with common Gram-negative pathogens including NME exhibiting MDR, DTR and carbapenem resistance and many β-lactam-resistant phenotypes of P. aeruginosa.

Prevalence of the virulence genes and their correlation with carbapenem resistance amongst the Pseudomonas aeruginosa strains isolated from a tertiary hospital in China

Pseudomonas aeruginosa is one of the top-listed pathogens in nosocomial infection. It is notorious for its complicated virulence system and rapid adaptability to drugs or antimicrobials. In this study, we aimed to evaluate the prevalence of sixteen virulence genes in four groups including type III secretion system, biofilm formation, extracellular toxin biosynthesis and enzymes amongst 209 clinical Pseudomonas aeruginosa strains. We investigated the different distribution patterns of virulence genotypes based on carbapenem-resistant phenotype or the carriage of carbapenemase genes. The detection rate of each virulence gene varied greatly. phzM and plcN were detected in all collected strains, while pilB and exoU were only carried by a small portion of isolates (6.7% and 16.3%). Additionally, the number of genotypes observed in each group of examined virulence genes ranged from 4 to 8. Only the distribution of genotypes of type III secretion system showed statistical difference between carbapenem-mediated or carbapenem-resistant and carbapenem-sensitive strains. The virulence genotype of Pseudomonas aeruginosa was possibly interrelated to its resistance mechanism. Further research suggested that one particular TTSS genotype exhibited higher ratio in carbapenemase-producing strains and exoS was less frequently detected in CRPA strains carrying carbapenemase gene. Generally, the significant genetic diversity of virulence genes amongst Pseudomonas aeruginosa strains was highlighted in this study. Specific TTSS genotypes were associated with carbapenem-resistance. In particular, certain incompatibility might exist between exoS and carbapenemase genes, which provided valuable information for further understanding the relationship between carbapenem resistance and virulence.

Acquired blaVIM and blaGES Carbapenemase-Encoding Genes in Pseudomonas aeruginosa: A Seven-Year Survey Highlighting an Increasing Epidemiological Threat

(1) Background: Pseudomonas aeruginosa is a Gram-negative bacterium with several intrinsic and acquired antimicrobial resistance mechanisms. The spread of carbapenemase-encoding genes, an acquired mechanism, enables carbapenem resistance in clinical settings. Detection of the carbapenemase-producer strains is urgent. Therefore, we aimed to characterize carbapenemase production in the clinical strains of P. aeruginosa at a tertiary-care center. (2) Methods: We included clinical strains of P. aeruginosa (from August 2011 to December 2018) with resistance towards at least one carbapenem. Strains were isolated in a tertiary-care center in Mexico City. Antimicrobial susceptibility profiles were determined by broth microdilution. Screening for carbapenemase-encoding genes was performed in all strains. Phenotypic assays (CarbaNP and mCIM) were conducted. Additional modifications to mCIM were also tested. (3) Results: One-hundred seventy-one P. aeruginosa strains out of 192 included in this study were resistant towards at least one of the carbapenems tested. Forty-seven of these strains harbored a carbapenemase-encoding gene. VIM (59.6%) and GES (23.4%) were the most frequently found carbapenemases in our study, followed by IMP (14.9%). (4) Among the most frequent carbapenemase genes identified, metallo-ß-lactamases were the most prevalent, which impair new treatment options. Searching for carbapenemase genes should be performed in resistant isolates to stop transmission and guide antimicrobial treatment.

In vitro activity of imipenem/relebactam against non-Morganellaceae Enterobacterales and Pseudomonas aeruginosa in the Asia-Pacific region: SMART 2017-2020

OBJECTIVES

To describe the in vitro activity of imipenem/relebactam (IMR) against non-Morganellaceae Enterobacterales (NME) and Pseudomonas aeruginosa, including piperacillin/tazobactam-nonsusceptible and meropenem-nonsusceptible isolates, infecting hospitalized patients in the Asia-Pacific region.

METHODS

From 2017 to 2020, 49 clinical laboratories in nine countries in the Asia-Pacific region participated in the SMART global surveillance program and contributed 26 783 NME and 6383 P. aeruginosa. Minimum inhibitory concentrations (MICs) were determined using CLSI broth microdilution and interpreted using CLSI M100 (2021) breakpoints. β-Lactamase genes were identified in selected isolate subsets (2017-2020) and oprD was sequenced in molecularly characterized P. aeruginosa collected in 2020.

RESULTS

Amikacin (97.9% susceptible), IMR (95.8%), meropenem (95.4%), and imipenem (92.6%) were the most active agents against NME. Among piperacillin/tazobactam-nonsusceptible NME (n=4070), 76.1% were IMR-susceptible (range by country, 97.5% [New Zealand] to 50.6% [Vietnam]); 22.4% of meropenem-nonsusceptible NME (n=1225) were IMR-susceptible (range by country, 68.8% [South Korea] to 7.6% [Thailand]). A total of 2.7% of NME carried a metallo-β-lactamase (MBL), 0.9% an OXA-48-like carbapenemase (MBL-negative), and 0.7% a KPC (MBL-negative). Amikacin (94.0% susceptible) and IMR (90.3%) were the most active agents against P. aeruginosa; 71.2% of isolates were imipenem-susceptible. Relebactam increased susceptibility to imipenem by 25.6% (from 40.5% to 66.1%) in piperacillin/tazobactam-nonsusceptible and by 44.8% (from 7.1% to 51.9%) in meropenem-nonsusceptible P. aeruginosa. Only 4.3% of P. aeruginosa were MBL-positive. A total of 70.3% (90/128) of IMR-nonsusceptible P. aeruginosa were oprD-deficient.

CONCLUSION

In 2017-2020, 96% of NME and 90% of P. aeruginosa from the Asia-Pacific region were IMR-susceptible. IMR percent susceptible rates were higher in countries with lower MBL carriage.

Temporal and geographical prevalence of carbapenem-resistant Pseudomonas aeruginosa and the in vitro activity of ceftolozane/tazobactam and comparators in Taiwan-SMART 2012-2021

OBJECTIVES

To determine the in vitro activities of ceftolozane/tazobactam (C/T) and comparators against Pseudomonas aeruginosa isolates cultured from hospitalised patient samples in Taiwan from 2012 to 2021 with an additional focus on the temporal and geographical prevalence of carbapenem-resistant P. aeruginosa (CRPA).

METHODS

P. aeruginosa isolates (n = 3013) were collected annually by clinical laboratories in northern (two medical centres), central (three medical centres), and southern Taiwan (four medical centres) as part of the SMART global surveillance program. MICs were determined by CLSI broth microdilution and interpreted using 2022 CLSI breakpoints. Molecular β-lactamase gene identification was performed on selected non-susceptible isolate subsets in 2015 and later.

RESULTS

Overall, 520 (17.3%) CRPA isolates were identified. The prevalence of CRPA increased from 11.5%-12.3% (2012-2015) to 19.4%-22.8% (2018-2021) (P ≤ 0.0001). Medical centres in northern Taiwan reported the highest percentages of CRPA. C/T, first tested in the SMART program in 2016, was highly active against all P. aeruginosa (97% susceptible), with annual susceptibility rates ranging from 94% (2017) to 99% (2020). Against CRPA, C/T inhibited >90% of isolates each year, with the exception of 2017 (79.4% susceptible). Most CRPA isolates (83%) were molecularly characterised, and only 2.1% (9/433) carried a carbapenemase (most commonly, VIM); all nine carbapenemase-positive isolates were from northern and central Taiwan.

CONCLUSION

The prevalence of CRPA increased significantly in Taiwan from 2012 to 2021 and warrants continued monitoring. In 2021, 97% of all P. aeruginosa and 92% of CRPA in Taiwan were C/T susceptible. Routine in vitro susceptibility testing of clinical isolates of P. aeruginosa against C/T, and other newer β-lactam/β-lactamase inhibitor combinations, appears prudent.

Antimicrobial Susceptibility Among Gram-Negative Isolates in Pediatric Patients in Latin America, Africa-Middle East, and Asia From 2016-2020 Compared to 2011-2015: Results From the ATLAS Surveillance Study

BACKGROUND

Antimicrobial resistance (AMR) data in the pediatric population are limited, particularly in developing countries. This study assessed the AMR profile and key resistance phenotypes and genotypes for Gram-negative bacteria (GNB) isolates collected as part of the Antimicrobial Testing Leadership and Surveillance program from pediatric patients in Latin America, Africa-Middle East, and Asia in 2016-2020 versus 2011-2015.

METHODS

Minimum inhibitory concentrations by broth microdilution methodology were interpreted per the Clinical and Laboratory Standards Institute. European Committee on Antimicrobial Susceptibility Testing breakpoints were used for interpreting colistin activity. β-lactamase genes were screened by polymerase chain reaction and sequencing.

RESULTS

For Acinetobacter baumannii, low susceptibility (<60.0%) was observed for all antimicrobials, except colistin (≥92.9%), across regions and year periods. Ceftazidime-avibactam, amikacin, colistin, and meropenem were mostly active (78.6%-100.0%) against Enterobacter cloacae, Escherichia coli, and Klebsiella pneumoniae. For Pseudomonas aeruginosa, susceptibility to ceftazidime-avibactam, amikacin, and colistin was ≥85.9%. Among resistance phenotypes, carbapenem-resistant (CR, ≥44.8%) and difficult-to-treat resistant (DTR, ≥37.1%) rates were the highest in A. baumannii. A consistent increase in CR and DTR K. pneumoniae was noted across regions over time. Extended-spectrum β-lactamases (ESBL)-producing K. pneumoniae (32.6%-55.6%) were more frequent than ESBL-producing E. coli (25.3%-37.1%). CTX-M was the dominant ESBL among Enterobacterales. NDM-positive Enterobacterales species and VIM-positive P. aeruginosa were identified across regions.

CONCLUSIONS

This study identified high susceptibility to few agents for key GNB in pediatric patients. Continued surveillance of resistance phenotypes and genotypes at regional levels may help to guide appropriate treatment decisions.

Comparison of In Vitro Activity of Ceftazidime-Avibactam and Imipenem-Relebactam against Clinical Isolates of Pseudomonas aeruginosa

The role of novel β-lactam/β-lactamase inhibitor combinations in ceftazidime-nonsusceptible (CAZ-NS) and imipenem-nonsusceptible (IPM-NS) Pseudomonas aeruginosa has not been fully elucidated. This study evaluated the in vitro activity of novel β-lactam/β-lactamase inhibitor combinations against Pseudomonas aeruginosa clinical isolates, determined how avibactam restored ceftazidime activity, and compared the activity of ceftazidime-avibactam (CZA) and imipenem-relebactam (IMR) against KPC-producing P. aeruginosa. Similar high susceptibility rates for CZA, IMR, and ceftolozane-tazobactam (88.9% to 89.8%) were found for 596 P. aeruginosa clinical isolates from 11 hospitals in China, and a higher susceptibility rate to ceftazidime than imipenem was observed (73.5% versus 63.1%). For CAZ-NS and IPM-NS isolates, susceptibility rates for CZA, ceftolozane-tazobactam, and IMR were 61.5% (75/122), 54.9% (67/122), and 51.6% (63/122), respectively. For CAZ-NS, IPM-NS but CZA-susceptible isolates, 34.7% (26/75) harbored acquired β-lactamases with KPC-2 predominant (n = 19), and 45.3% (34/75) presented overexpression of chromosomal β-lactamase ampC. Among 22 isolates carrying KPC-2 carbapenemase alone, susceptibility rates to CZA and IMR were 86.4% (19/22) and 9.1% (2/22), respectively. Notably, 95% (19/20) of IMR-nonsusceptible isolates had an inactivating mutation of oprD gene. In conclusion, CZA, ceftolozane-tazobactam, and IMR exhibit high activity against P. aeruginosa, and CZA is more active than IMR against CAZ-NS and IPM-NS isolates as well as KPC-producing P. aeruginosa. Avibactam overcomes ceftazidime resistance engendered by KPC-2 enzyme and overexpressed AmpC. IMPORTANCE The emergence of antimicrobial resistance poses a particular challenge globally, and the concept of P. aeruginosa with "difficult-to-treat" resistance (DTR-P. aeruginosa) was proposed. Here, P. aeruginosa clinical isolates were highly susceptible to three β-lactamase inhibitor combinations, CZA, IMR, and ceftolozane-tazobactam. The combination of KPC-2 enzyme and nonfunctional porin OprD contributed to IMR resistance in P. aeruginosa, and CZA was more active than IMR in fighting against KPC-2-producing P. aeruginosa. CZA also showed good activity against CAZ-NS and IPM-NS P. aeruginosa, primarily by inhibiting KPC-2 enzyme and overproduced AmpC, supporting the clinical use of CZA in the treatment of infections caused by DTR-P. aeruginosa.

Carbapenem-Resistant Pseudomonas aeruginosa Bacteremia, through a Six-Year Infection Control Program in a Hospital

BACKGROUND

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a life-threatening healthcare-associated infection affecting especially patients with immunosuppression and comorbidities. We investigated the association between the incidence of CRPA bacteremia, antibiotic consumption, and infection control measures in a hospital during 2013-2018.

METHODS

We prospectively recorded the incidence of CRPA bacteremia, antibiotic consumption, use of hand-hygiene solutions, and isolation rates of multidrug-resistant (MDR) carrier patients.

FINDINGS

The consumption of colistin, aminoglycosides, and third-generation cephalosporins decreased significantly in the total hospital and its divisions (p-value < 0.001 for all comparisons) while the consumption of carbapenems decreased significantly in the adults ICU (p-value = 0.025). In addition, the incidence of CRPA significantly decreased in the total hospital clinics and departments (p-values = 0.027 and 0.042, respectively) and in adults clinics and departments (p-values = 0.031 and 0.051, respectively), while in the adults ICU, the incidence remained unchanged. Increased isolation rates of MDR carrier patients, even two months before, significantly correlated with decreased incidence of CRPA bacteremia (IRR: 0.20, 95% CI: 0.05-0.73, p-value = 0.015) in the adults ICU. Interestingly, when the use of hand-hygiene solutions (alcohol and/or scrub) increased, the consumption of advanced, nonadvanced, and all antibiotics decreased significantly.

CONCLUSION

In our hospital, multimodal infection control interventions resulted in a significant reduction of CRPA bacteremia, mostly due to the reduction of all classes of antibiotics.

Global epidemiology and clinical outcomes of carbapenem-resistant Pseudomonas aeruginosa and associated carbapenemases (POP): a prospective cohort study

BACKGROUND

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a global threat, but the distribution and clinical significance of carbapenemases are unclear. The aim of this study was to define characteristics and outcomes of CRPA infections and the global frequency and clinical impact of carbapenemases harboured by CRPA.

METHODS

We conducted an observational, prospective cohort study of CRPA isolated from bloodstream, respiratory, urine, or wound cultures of patients at 44 hospitals (10 countries) between Dec 1, 2018, and Nov 30, 2019. Clinical data were abstracted from health records and CRPA isolates were whole-genome sequenced. The primary outcome was 30-day mortality from the day the index culture was collected. We compared outcomes of patients with CRPA infections by infection type and across geographic regions and performed an inverse probability weighted analysis to assess the association between carbapenemase production and 30-day mortality.

FINDINGS

We enrolled 972 patients (USA n=527, China n=171, south and central America n=127, Middle East n=91, Australia and Singapore n=56), of whom 581 (60%) had CRPA infections. 30-day mortality differed by infection type (bloodstream 21 [30%] of 69, respiratory 69 [19%] of 358, wound nine [14%] of 66, urine six [7%] of 88; p=0·0012) and geographical region (Middle East 15 [29%] of 52, south and central America 20 [27%] of 73, USA 60 [19%] of 308, Australia and Singapore three [11%] of 28, China seven [6%] of 120; p=0·0002). Prevalence of carbapenemase genes among CRPA isolates also varied by region (south and central America 88 [69%] of 127, Australia and Singapore 32 [57%] of 56, China 54 [32%] of 171, Middle East 27 [30%] of 91, USA ten [2%] of 527; p<0·0001). KPC-2 (n=103 [49%]) and VIM-2 (n=75 [36%]) were the most common carbapenemases in 211 carbapenemase-producing isolates. After excluding USA patients, because few US isolates had carbapenemases, patients with carbapenemase-producing CRPA infections had higher 30-day mortality than those with non-carbapenemase-producing CRPA infections in both unadjusted (26 [22%] of 120 vs 19 [12%] of 153; difference 9%, 95% CI 3-16) and adjusted (difference 7%, 95% CI 1-14) analyses.

INTERPRETATION

The emergence of different carbapenemases among CRPA isolates in different geographical regions and the increased mortality associated with carbapenemase-producing CRPA infections highlight the therapeutic challenges posed by these organisms.

FUNDING

National Institutes of Health.

Carbapenem-resistant Pseudomonas aeruginosa infections in critically ill children: Prevalence, risk factors, and impact on outcome in a large tertiary pediatric hospital of China

Background and aims

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a major cause of healthcare-associated infections worldwide, but comprehensive study of clinical characteristics for CRPA infections among critically ill children remains limited in China. The objective of this study was to determine the epidemiology, risk factors, and clinical outcomes of CRPA infections among critically ill pediatric patients in a large tertiary pediatric hospital in China.

Methods

A retrospective case-control study of patients with P. aeruginosa infections was conducted in the three intensive care units (ICUs) of Shanghai Children's Medical Center from January 2016 to December 2021. All patients with CRPA infection in the ICUs were enrolled as case patients. Patients with carbapenem-susceptible P. aeruginosa (CSPA) infection were randomly selected as control patients in a ratio of 1:1. Clinical characteristics of those inpatients were reviewed through the hospital information system. Univariate and multivariate analyses were performed to evaluate risk factors associated with the development of CRPA infections and mortality of P. aeruginosa infections.

Results

A total of 528 cases of P. aeruginosa infection in the ICUs were enrolled in the 6-year study. The prevalence of CRPA and MDRPA (multidrug-resistance P. aeruginosa) was 18.4 and 25.6%, respectively. Significant risk factors related to CRPA infection were the length of hospitalization >28 days (OR = 3.241, 95% CI 1.622-6.473, p = 0.001), receiving invasive operations (OR = 2.393, 95% CI 1.196-4.788, p = 0.014) and a blood transfusion (OR = 7.003, 95% CI 2.416-20.297, p < 0.001) within 30 days before infection. Conversely, birth weight ≥2,500 g (OR = 0.278, 95% CI 0.122-0.635, p = 0.001) and breast nursing (OR = 0.362, 95% CI 0.168-0.777, p = 0.009) were significant protective factors against CRPA infections. The in-hospital mortality rate was 14.2%, and no difference in mortality was observed between patients with CRPA and CSPA infections. Platelet < 100 × 10⁹/L (OR = 5.729, 95% CI 1.048-31.308, p = 0.044) and serum urea <3.2 mmol/L (OR = 5.173, 95% CI 1.215-22.023, p = 0.026) were independent predictors for the mortality due to P. aeruginosa infection.

Conclusions

Our findings provide insights into CRPA infections among critically ill children in China. They provide guidance in identifying patients that may be at high risk for a resistant infection and emphasize the importance of antimicrobial stewardship and infection control in hospitals.

Geographic patterns of carbapenem-resistant, multi-drug-resistant and difficult-to-treat Acinetobacter baumannii in the Asia-Pacific region: results from the Antimicrobial Testing Leadership and Surveillance (ATLAS) program, 2020

This study evaluated the in-vitro activity of multiple classes of antibiotics, including novel β-lactam combination agents, tigecycline and colistin, against carbapenem-resistant (CRAB), multi-drug-resistant (MDRAB) and difficult-to-treat (DTRAB) Acinetobacter baumannii. Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method. Susceptibility profiles and the distribution of selected antimicrobials among countries were illustrated and examined based on the breakpoints of the Clinical and Laboratory Standards Institute, European Committee on Antimicrobial Susceptibility Testing and the US Food and Drug Administration. In total, 847 A. baumannii isolates were evaluated, and 692 isolates were characterized as CRAB, MDRAB or DTRAB. The prevalence of drug-resistant A. baumannii was >70.0% in South Korea, India and China, while the resistance rate of tigecycline was <5.5%. The MICs of meropenem and meropenem/vaborbactam for drug-resistant A. baumannii were equal (both MIC₅₀ and MIC₉₀ were 32 mg/L, range 0.25-32 mg/L). The overall resistance rate remained high for multiple classes of antibiotics, including penicillins, cephalosporins, carbapenems, quinolones and aminoglycosides (>84.0%, >96.0%, >98.0%, >88.0% and >87.0%, respectively), but not colistin or tigecycline (1.1% and 4.3%, respectively). China showed the lowest susceptibility to tigecycline for drug-resistant A. baumannii isolates compared with other countries. In conclusion, the resistance rate of drug-resistant A. baumannii remains high against multiple classes of antimicrobials. Colistin was the most potent agent, followed by tigecycline. The geographic pattern of tigecycline-resistant A. baumannii varied among countries. Therefore, continuous surveillance of A. baumannii resistance profiles in different regions is required.

Geographic patterns of global isolates of carbapenem-resistant Klebsiella pneumoniae and the activity of ceftazidime/avibactam, meropenem/vaborbactam, and comparators against these isolates: Results from the Antimicrobial Testing Leadership and Surveillance (ATLAS) program, 2020

Carbapenem-resistant Enterobacterales (CRE) are a growing threat to public health. This study was conducted to determine the prevalence of carbapenem-resistant Klebsiella pneumoniae (CR-KP) and the associated carbapenemase genes using data from the Antimicrobial Testing Leadership and Surveillance (ATLAS) program, 2020. Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method, and carbapenemase genes were detected using multiplex polymerase chain reaction (PCR). Clinical and Laboratory Standards Institute breakpoints were used for interpretation of susceptibility. A total of 6753 K. pneumoniae isolates were collected from 57 countries in six regions worldwide. Of these, 1118 (16.6%) were CR-KP isolates. Among 1079 of the tested CR-KP isolates, 1017 (94.3%) had at least one of the class A (41.0%, 417/1017), B (39.3%, 400/1017), and D (38.8%, 395/1017) carbapenemase genes. The resistance patterns and associated genes differed significantly between the participating countries. India, Greece, and Argentina had the highest rates of carbapenem resistance. Susceptibility to the β-lactamase inhibitor combination, ceftazidime/avibactam was greater than that to meropenem/vaborbactam in all K. pneumoniae (93.7% vs. 90.3%, P < 0.05), CR-KP (63.3% vs. 41.5%, P < 0.05), CR-KP with genes for Klebsiella pneumoniae carbapenemase-like carbapenemase (99.5% vs. 96.0%, P < 0.05), oxacillinase-like carbapenemase (98.7% vs. 4.6%, P < 0.05), and CR-KP without carbapenemase genes (93.5% vs. 79.0%, P < 0.05). CR-KP was the only exception with class B carbapenemase, with susceptibility rates of 1.4% and 9.4% to ceftazidime/avibactam and meropenem/vaborbactam, respectively (P < 0.05). Overall, surveillance results are important for guiding empirical antimicrobial therapy in different regions and for monitoring the global transmission of CR-KP with varying resistance mechanisms.

Molecular mechanisms underlying bacterial resistance to ceftazidime/avibactam

Ceftazidime/avibactam (CAZ/AVI), a combination of ceftazidime and a novel β-lactamase inhibitor (avibactam) that has been approved by the U.S. Food and Drug Administration, the European Union, and the National Regulatory Administration in China. CAZ/AVI is used mainly to treat complicated urinary tract infections and complicated intra-abdominal infections in adults, as well as to treat patients infected with Carbapenem-resistant Enterobacteriaceae (CRE) susceptible to CAZ/AVI. However, increased clinical application of CAZ/AVI has resulted in the development of resistant strains. Mechanisms of resistance in most of these strains have been attributed to bla_KPC mutations, which lead to amino acid substitutions in β-lactamase and changes in gene expression. Resistance to CAZ/AVI is also associated with reduced expression and loss of outer membrane proteins or overexpression of efflux pumps. In this review, the prevalence of CAZ/AVI-resistance bacteria, resistance mechanisms, and selection of detection methods of CAZ/AVI are demonstrated, aiming to provide scientific evidence for the clinical prevention and treatment of CAZ/AVI resistant strains, and provide guidance for the development of new drugs. This article is categorized under: Infectious Diseases > Molecular and Cellular Physiology.