Mechanisms of carbapenem resistance in endemic Pseudomonas aeruginosa isolates after an SPM-1 metallo-β-lactamase producing strain subsided in an intensive care unit of a teaching hospital in Brazil

The Prevalence of Metallo-Beta-Lactamese-(MβL)-Producing Pseudomonas aeruginosa Isolates in Brazil: A Systematic Review and Meta-Analysis

The purpose of the current study is to describe the prevalence of Pseudomonas aeruginosa (PA)-producing MβL among Brazilian isolates and the frequency of blaSPM-1 in MβL-PA-producing isolates. From January 2009 to August 2023, we carried out an investigation on this subject in the internet databases SciELO, PubMed, Science Direct, and LILACS. A total of 20 papers that met the eligibility requirements were chosen by comprehensive meta-analysis software v2.2 for data retrieval and analysis by one meta-analysis using a fixed-effects model for the two investigations. The prevalence of MβL-producing P. aeruginosa was 35.8% or 0.358 (95% CI = 0.324-0.393). The studies' differences were significantly different from one another (x2 = 243.15; p < 0.001; I2 = 92.18%), so they were divided into subgroups based on Brazilian regions. There was indication of asymmetry in the meta-analyses' publishing bias funnel plot; so, a meta-regression was conducted by the study's publication year. According to the findings of Begg's test, no discernible publishing bias was found. blaSPM-1 prevalence was estimated at 66.9% or 0.669 in MβL-PA isolates (95% CI = 0.593-0.738). The analysis of this one showed an average heterogeneity (x2 = 90.93; p < 0.001; I2 = 80.20%). According to the results of Begg's test and a funnel plot, no discernible publishing bias was found. The research showed that MβL-P. aeruginosa and SPM-1 isolates were relatively common among individuals in Brazil. P. aeruginosa and other opportunistic bacteria are spreading quickly and causing severe infections, so efforts are needed to pinpoint risk factors, reservoirs, transmission pathways, and the origin of infection.

Endemic High-Risk Clone ST277 Is Related to the Spread of SPM-1-Producing Pseudomonas aeruginosa during the COVID-19 Pandemic Period in Northern Brazil

Pseudomonas aeruginosa is a high-priority bacterial agent that causes healthcare-acquired infections (HAIs), which often leads to serious infections and poor prognosis in vulnerable patients. Its increasing resistance to antimicrobials, associated with SPM production, is a case of public health concern. Therefore, this study aims to determine the antimicrobial resistance, virulence, and genotyping features of P. aeruginosa strains producing SPM-1 in the Northern region of Brazil. To determine the presence of virulence and resistance genes, the PCR technique was used. For the susceptibility profile of antimicrobials, the Kirby-Bauer disk diffusion method was performed on Mueller-Hinton agar. The MLST technique was used to define the ST of the isolates. The exoS+/exoU- virulotype was standard for all strains, with the aprA, lasA, toxA, exoS, exoT, and exoY genes as the most prevalent. All the isolates showed an MDR or XDR profile against the six classes of antimicrobials tested. HRC ST277 played a major role in spreading the SPM-1-producing P. aeruginosa strains.

Genomics and Antimicrobial Susceptibility of Clinical Pseudomonas aeruginosa Isolates from Hospitals in Brazil

Pseudomonas aeruginosa, an opportunistic pathogen causing infections in immunocompromised patients, usually shows pronounced antimicrobial resistance. In recent years, the frequency of carbapenemases in P. aeruginosa has decreased, which allows use of new beta-lactams/combinations in antimicrobial therapy. Therefore, the in vitro evaluation of these drugs in contemporary isolates is warranted. We evaluated the antimicrobial susceptibility and genomic aspects of 119 clinical P. aeruginosa isolates from 24 different hospitals in Brazil in 2021-2022. Identification was performed via MALDI-TOF-MS, and antimicrobial susceptibility was identified through broth microdilution, gradient tests, or disk diffusion. Whole-genome sequencing was carried out using NextSeq equipment. The most active drug was cefiderocol (100%), followed by ceftazidime-avibactam (94.1%), ceftolozane-tazobactam (92.4%), and imipenem-relebactam (81.5%). Imipenem susceptibility was detected in 59 isolates (49.6%), and the most active aminoglycoside was tobramycin, to which 99 (83.2%) isolates were susceptible. Seventy-one different sequence types (STs) were detected, including twelve new STs described herein. The acquired resistance genes bla_CTX-M-2 and bla_KPC-2 were identified in ten (8.4%) and two (1.7%) isolates, respectively. Several virulence genes (exoSTUY, toxA, aprA, lasA/B, plcH) were also identified. We found that new antimicrobials are effective against the diverse P. aeruginosa population that has been circulating in Brazilian hospitals in recent years.

Antimicrobial Resistance in Romania: Updates on Gram-Negative ESCAPE Pathogens in the Clinical, Veterinary, and Aquatic Sectors

Multidrug-resistant Gram-negative bacteria such as Acinetobacter baumannii, Pseudomonas aeruginosa, and members of the Enterobacterales order are a challenging multi-sectorial and global threat, being listed by the WHO in the priority list of pathogens requiring the urgent discovery and development of therapeutic strategies. We present here an overview of the antibiotic resistance profiles and epidemiology of Gram-negative pathogens listed in the ESCAPE group circulating in Romania. The review starts with a discussion of the mechanisms and clinical significance of Gram-negative bacteria, the most frequent genetic determinants of resistance, and then summarizes and discusses the epidemiological studies reported for A. baumannii, P. aeruginosa, and Enterobacterales-resistant strains circulating in Romania, both in hospital and veterinary settings and mirrored in the aquatic environment. The Romanian landscape of Gram-negative pathogens included in the ESCAPE list reveals that all significant, clinically relevant, globally spread antibiotic resistance genes and carrying platforms are well established in different geographical areas of Romania and have already been disseminated beyond clinical settings.

Broad-spectrum antimicrobial consumption trend and correlation with bacterial infections and resistance over 5 years

OBJECTIVES

Consumption trends of four broad spectrum antimicrobials and their correlation with resistance in Gram-negative bacilli (GNB) from 2013 to 2017 within intensive care units were explored.

METHODS

Consumption meropenem (MEM), polymyxin B (PMB), piperacillin-tazobactam (PTZ), and cefepime (FEP) in DDD/1,000 patient-days was measured. Infection-related GNB isolates were grouped according to specific resistance profiles. Time series of antimicrobial consumption and their parametric correlation with each grouped resistant GNB were explored.

RESULTS

A total of 1,423 GNB were evaluated. A significant linear decline in consumption was observed for MEM (slope -3.88, CI95% -4.96 to -2.81, p < 0.0001) and for PMB (slope -3.51, CI95% -5.528 to -1.495, p = 0.0009). A significant decline for MEM non-susceptible Acinetobacter spp. (R² = 0.476, p = 0.006) and an increase in FEP non-susceptible E. coli (R² = 0.124, p = 0.006) were observed. A significant correlation between MEM consumption and MEM non-susceptible Acinetobacter spp. (r = 0.43, p = 0.001) was observed. MEM consumption and MEM non-susceptible Acinetobacter spp. showed a correlation.

CONCLUSIONS

Reduction in consumption of broad-spectrum antimicrobials may alter the frequency of infection-related isolates and their resistance profiles.

Evaluation of in vitro activity of ceftolozane-tazobactam in combination with other classes of antibacterial agents against Enterobacterales and Pseudomonas aeruginosa-the EM200 study

Ceftolozane-tazobactam is a cephalosporin/β-lactamase inhibitor combination developed for use against some β-lactam- and multidrug-resistant Gram-negative organisms. This study aimed to evaluate the in vitro activity of ceftolozane-tazobactam against clinical bacterial isolates at the University Hospital of Marrakech. This is a descriptive and analytical prospective study. A total of 143 Enterobacterales and 48 Pseudomonas aeruginosa isolates were collected from January 2018 to December 2018 from patients with respiratory, urinary and intra-abdominal infections. The identification was made by Phoenix automated system (BioMérieux). MIC50/90 were tested by broth microdilution for ceftolozane-tazobactam, and other drugs using dried panels. Antimicrobial susceptibility results were interpreted according to CLSI guidelines. Ceftolozane-tazobactam inhibited 98% of Escherichia coli (MIC_50/90; 0.25/0.5 μg/mL). The susceptibility rate of Klebsiella pneumoniae to ceftolozane-tazobactam was 68.8% (MIC_50/90, 0.5/>32 μg/mL); other Enterobacterales have shown susceptibility rates of 80.4% (MIC_50/90; 0.5/8 μg/mL). In carbapenemase-producing K. pneumoniae, the bla _OXA-48 mutation was found in two isolates. Susceptibility of P. aeruginosa to ceftolozane-tazobactam was 91.7% (MIC_50/90, 0.5/>32 μg/mL). In non-carbapenemase-producing P. aeruginosa, AmpC mutations were found in all isolates. Ceftolozane-tazobactam was satisfactorily active against a wide range of tested isolates and offers clinicians a potential therapeutic option even against resistant strains in patients with intra-abdominal infections, urinary tract infections and nosocomial pneumonia.

Update on the epidemiology of carbapenemases in Latin America and the Caribbean

INTRODUCTION

Carbapenemases are β-lactamases able to hydrolyze a wide range of β-lactam antibiotics, including carbapenems. Carbapenemase production in Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter spp., with and without the co-expression of other β-lactamases is a serious public health threat. Carbapenemases belong to three main classes according to the Ambler classification: class A, class B, and class D.

AREAS COVERED

Carbapenemase-bearing pathogens are endemic in Latin America. In this review, we update the status of carbapenemases in Latin America and the Caribbean.

EXPERT OPINION

Understanding the current epidemiology of carbapenemases in Latin America and the Caribbean is of critical importance to improve infection control policies limiting the dissemination of multi-drug-resistant pathogens and in implementing appropriate antimicrobial therapy.

High prevalence of atypical virulotype and genetically diverse background among Pseudomonas aeruginosa isolates from a referral hospital in the Brazilian Amazon

Pseudomonas aeruginosa is an opportunistic pathogen causing different types of infections, particularly in intensive care unit patients. Characteristics that favor its persistence artificial environments are related to its high adaptability, wide arsenal of virulence factors and resistance to several antimicrobial classes. Among the several virulence determinants, T3SS stands as the most important due to the clinical impact of exoS and exoU genes in patient’s outcome. The molecular characterization of P. aeruginosa isolates helps in the comprehension of transmission dynamics and enhance knowledge of virulence and resistance roles in infection process. In the present study, we investigated virulence and resistance properties and the genetic background of P. aeruginosa isolated from ICUs patients at a referral hospital in Brazilian Amazon. A total of 54 P. aeruginosa isolates were characterized by detecting 19 virulence-related genes, antimicrobial susceptibility testing, molecular detection of β-lactamase-encoding genes and genotyping by MLST and rep-PCR. Our findings showed high prevalence of virulence-related markers, where 53.7% of the isolates presented at least 17 genes among the 19 investigated (P = 0.01). The rare exoS⁺/exoU⁺ cytotoxic virulotype was detected in 55.6% of isolates. Antimicrobial susceptibility testing revealed percentages of antibiotic resistance above 50% to carbapenems, cephalosporins and fluoroquinolones associated to MDR/XDR isolates. Isolates harboring both bla_SPM-1 and bla_OXA genes were also detected. Genotyping methods demonstrated a wide genetic diversity of strains spread among the different intensive care units, circulation of international MDR/XDR high-risk clones (ST111, ST235, ST244 and ST277) and emergence of seven novel MLST lineages. Finally, our findings highlight the circulation of strains with high virulence potential and resistance to antimicrobials and may be useful on comprehension of pathogenicity process, treatment guidance and establishment of strategies to control the spread of epidemic P. aeruginosa strains.

Activity of ceftolozane-tazobactam and comparators against gram-negative bacilli: Results from the study for monitoring antimicrobial resistance trends (SMART - Brazil; 2016-2017)

Multi-drug resistant Gram-negative bacilli (GNB) have been reported as cause of serious hospital-acquired infections worldwide. The aim of this study was to investigate the in vitro activity of ceftolozane-tazobactam compared to other agents against GNB isolated from patients admitted to Brazilian medical centers between the years 2016 and 2017. Presence of β-lactamase encoding genes was also evaluated.

Methods

Antimicrobial susceptibility testing of GNB isolated from intra-abdominal (IAI), respiratory (RTI), and urinary tract infections (UTI) was performed according to ISO 227-1 guidelines and interpreted following CLSI and BrCAST/EUCAST guidelines. Qualifying Enterobacteriaceae isolates were screened for the presence of β-lactamase genes by PCR followed by DNA sequencing.

Results

1748 GNB collected from UTI (45.2%), IAI (25.7%) and RTI (29.1%) were evaluated. Ceftolozane-tazobactam remained highly active (94.7%) against E. coli isolates. Among K. pneumoniae, susceptibility rates were 85.9% and 85.4% for amikacin and colistin, whereas ceftolozane-tazobactam (44.1% susceptible) and carbapenems (55.2-62.2% susceptible) showed poor activity due to bla_KPC-2. Against E. cloacae amikacin, imipenem, and meropenem retained good activity (>90%). Ceftolozane-tazobactam was the most potent β-lactam agent tested against P. aeruginosa (90.9% susceptible), including ceftazidime and imipenem resistant isolates. β-lactamase encoding genes testing was carried out in 433 isolates. bla_CTX-M variants were predominant in E. coli, P. mirabilis and E. cloacae. Among the K. pneumoniae molecularly tested, most carried bla_KPC (68.5%), with all harboring bla_KPC-2, except two isolates carrying bla_KPC-3 or bla_KPC-30. ESBL encoding genes, mainly CTX-M family, were frequently detected in K. pneumoniae, plasmid-mediated AmpC were rare. A variety of PDC encoding genes were detected in P. aeruginosa isolates with five isolates harboring MBL and one KPC encoding genes.

Conclusion

Ceftolozane-tazobactam was very active against E. coli, P. mirabilis and P. aeruginosa isolates and could constitute an excellent therapeutic option including for those isolates resistant to extended-spectrum cephalosporins and carbapenems but not producers of carbapenemases.

Evaluation of in vitro activity of ceftolozane-tazobactam against recent clinical bacterial isolates from Brazil - the EM200 study

Background

The emergence of antibiotic resistance is increasing and there are few effective antibiotics to treat infections caused by resistant and multidrug resistant bacterial pathogens. This study aimed to evaluate the in vitro activity of ceftolozane–tazobactam against clinical bacterial isolates from Brazil.

Methods

A total of 673 Gram-negative bacterial isolates including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and other Enterobacterales collected from 2016 to 2017 were tested, most of them isolated from patients in intensive care units. Minimum inhibitory concentrations (MIC_50/90) were determined by broth microdilution for amikacin, aztreonam, cefepime, cefotaxime, cefoxitin, ceftolozane–tazobactam, ceftazidime, ceftriaxone, ciprofloxacin, colistin, ertapenem, imipenem, levofloxacin, meropenem, and piperacillin-tazobactam using dried panels. Antimicrobial susceptibility results were interpreted according to Clinical and Laboratory Standards Institute criteria.

Results

Susceptibility rates to ceftolozane–tazobactam ranged from 40.4% to 94.9%. P. aeruginosa susceptibility rate to ceftolozane–tazobactam was 84.9% (MIC_50/90, 1/16 μg/mL) and 99.2% to colistin. For E. coli, ceftolozane–tazobactam inhibited 94.9% (MIC_50/90, 0.25/1 μg/mL) of the microorganisms. The susceptibility rate of K. pneumoniae to ceftolozane–tazobactam was 40.4% (MIC_50/90, 16/>32 μg/mL). Other Enterobacterales have shown susceptibility rates of 81.1% (MIC_50/90, 0.5/16 μg/mL) to ceftolozane–tazobactam, 93.9% to meropenem, 90.9% to amikacin (90.9%), and 88.6% to ertapenem. In non-carbapenemase producing isolates, AmpC mutations were found three isolates.

Conclusions

Ceftolozane–tazobactam has shown relevant activity against a large variety of the analyzed microorganisms collected from multiple centers in Brazil, showing promising results even in multidrug resistant strains.

The Current Burden of Carbapenemases: Review of Significant Properties and Dissemination among Gram-Negative Bacteria

Carbapenemases are β-lactamases belonging to different Ambler classes (A, B, D) and can be encoded by both chromosomal and plasmid-mediated genes. These enzymes represent the most potent β-lactamases, which hydrolyze a broad variety of β-lactams, including carbapenems, cephalosporins, penicillin, and aztreonam. The major issues associated with carbapenemase production are clinical due to compromising the activity of the last resort antibiotics used for treating serious infections, and epidemiological due to their dissemination into various bacteria across almost all geographic regions. Carbapenemase-producing Enterobacteriaceae have received more attention upon their first report in the early 1990s. Currently, there is increased awareness of the impact of nonfermenting bacteria, such as Acinetobacter baumannii and Pseudomonas aeruginosa, as well as other Gram-negative bacteria that are carbapenemase-producers. Outside the scope of clinical importance, carbapenemases are also detected in bacteria from environmental and zoonotic niches, which raises greater concerns over their prevalence, and the need for public health measures to control consequences of their propagation. The aims of the current review are to define and categorize the different families of carbapenemases, and to overview the main lines of their spread across different bacterial groups.

Epidemiology and antibiotic resistance trends in clinical isolates of Pseudomonas aeruginosa from Rio de janeiro - Brazil: Importance of mutational mechanisms over the years (1995-2015)

Pseudomonas aeruginosa is a major health concern globally and treating infections caused by MDR-isolates unarguably a humongous challenge that remains an unmet need in modern medicine. To determine patterns and mechanisms of antimicrobial resistance and its spread over the years in Rio de Janeiro, Brazil, 88 P. aeruginosa isolates were selected from 1995 to 2015. Phenotypic and genotypic characterization of antimicrobial resistance was evaluated and isolates were submitted to clonality by PFGE and MLST. PFGE analysis showed a great variability of clonal groups mainly over the past 10 years of this study. STs predominant in the early years (ST804, ST1860, ST487 and ST1602) associated to multidrug resistance (MDR) phenotype were replaced by ST277, ST244, ST1945, ST1791 with extensive drug resistance (XDR) in last years, with significant increase in resistance to carbapenems, fluoroquinolones and aminoglycosides. Colistin resistance was detected in 3.5%. The main mechanisms of antimicrobial resistance were mutational mechanisms (mutations in oprD, mexT and gyrA genes). We found the ESBL genes bla_TEM (n = 2), bla_SHV (n = 3) and bla_CTX (n = 1).The carbapenemases genes was present in ST277 (bla_SPM, n = 3), ST1560 (bla_KPC, n = 3) and ST1944 (bla_KPC, n = 2). The 16S RNA methylase gene (rmtD) was found in five isolates belonged to ST277. In conclusion, molecular epidemiological investigation reveals an increase of antimicrobial resistance in P. aeruginosa over 21 years in Rio de Janeiro with higher population structure and occurrence of high risk clone in the last years. The mutational mechanisms of resistance were present in all XDR isolates.

Geographic and Temporal Patterns of Antimicrobial Resistance in Pseudomonas aeruginosa Over 20 Years From the SENTRY Antimicrobial Surveillance Program, 1997-2016

Background

The SENTRY Antimicrobial Surveillance Program was established in 1997 and encompasses over 750 000 bacterial isolates from ≥400 medical centers worldwide. Among the pathogens tested, Pseudomonas aeruginosa remains a common cause of multidrug-resistant (MDR) bloodstream infections and pneumonia in hospitalized patients. In the present study, we reviewed geographic and temporal trends in resistant phenotypes of P. aeruginosa over 20 years of the SENTRY Program.

Methods

From 1997 to 2016, 52 022 clinically significant consecutive isolates were submitted from ≥200 medical centers representing the Asia-Pacific region, Europe, Latin America, and North America. Only 1 isolate per patient per infection episode was submitted. Isolates were identified by standard algorithms and/or matrix-assisted laser desorption ionization-time of flight mass spectrometry. Susceptibility testing was performed by Clinical and Laboratory Standards Institute (CLSI) methods and interpreted using CLSI and European Committee on Antimicrobial Susceptibility Testing 2018 criteria at JMI Laboratories.

Results

The most common infection from which P. aeruginosa was isolated was pneumonia in hospitalized patients (44.6%) followed by bloodstream infection (27.9%), with pneumonia having a slightly higher rate of MDR (27.7%) than bloodstream infections (23.7%). The region with the highest percentage of MDR phenotypes was Latin America (41.1%), followed by Europe (28.4%). The MDR rates were highest in 2005–2008 and have decreased in the most recent period. Colistin was the most active drug tested (99.4% susceptible), followed by amikacin (90.5% susceptible).

Conclusions

Over the 20 years of SENTRY Program surveillance, the rate of MDR P. aeruginosa infections has decreased, particularly in Latin America. Whether the trend of decreasing resistance in P. aeruginosa is maintained will be documented in future SENTRY Program and other surveillance reports.