Carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) are listed by World Health Organization (WHO) as priority antimicrobial-resistant bacteria. Data on WHO Priority Antimicrobial resistance Phenotype (WPAP) bacteria from low- and middle-income countries are scarce. In this study, we investigated the occurrence of WPAP in healthcare-associated bloodstream infections (BSI) in Brazil, an upper-middle-income country in South America. ASCENSION was a prospective, multicentre, observational study conducted in 14 hospitals from four of five Brazilian regions. Enterobacterales, A. baumannii, P. aeruginosa, S. aureus and E. faecium BSIs in hospitalised patients were analysed. The primary outcome was the frequency of WPAP among all bacteria of interest. Secondary outcomes were incidence-density of bacteria isolates in hospitalised patients, WPAP proportions within bacterial species, and 28-day mortality. PCR for carbapenemase genes was performed in carbapenem-resistant Gram-negative bacteria. Between August 15, 2022, and August 14, 2023, 1350 isolates (1220 BSI episodes) were included. WPAP accounted for 38.8% (n = 524; 95% Confidence Interval 32.0–46.1) of all isolates, with CRE (19.3%) as the most frequent, followed by CRAB (9.6%), MRSA (4.9%), VRE (2.7%), and CRPA (2.4%). Incidence-density of all and WPAP isolates were 1.91 and 0.77/1000 patients-day, respectively. Carbapenem-resistant Klebsiella pneumoniae (CRKP) was the most common CRE, corresponding to 14.2% of all BSIs. A. baumannii isolates presented the highest proportion of WPAP (87.8%). Mortality rates were higher in patients with BSIs by WPAP than non-WPAP isolates. KPC (64.4%) was the predominant carbapenemase in CRE, followed by NDM (28.4%) and KPC + NDM co-production (7.1%). OXA-23 was the most frequent in CRAB. A high frequency of WPAP bacteria, particularly CRKP and CRAB, were found in healthcare-associated BSIs in Brazil, posing them as a major public health problem in this country. 10.13039/501100003593 National Council for Scientific and Technological Development , Brazil.

Antimicrobial treatment of patients with bloodstream infections (BSI) is time-sensitive. In an era of increasing antimicrobial resistance, rapid detection and identification of bacteria with antimicrobial susceptibility are critical for targeted therapy early in the disease course. This study describes the performance of a rapid method for identifying and testing antimicrobial susceptibility of Gram-negative bacteria performed directly from blood culture bottles in a routine microbiology laboratory. A total of 284, 120, and 24 samples were analyzed by rapid identification (Rid), rapid susceptibility testing (RAST), and rapid broth microdilution for polymyxin B (rMIC), respectively, and compared with standard methods. Our protocol was able to identify 93% of isolates at the species level using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). We obtained 100% agreement for RAST compared to the standard method and 96% agreement for rMIC. Our protocol has proven to be an excellent tool for rapid identification of Gram-negative bacilli causing BSIs. It can also be used in microbiology laboratory routine along with RAST and faster polymyxin microdilution, especially for carbapenemase-producing bacteria, allowing for rapid, simple, accurate, and cost-effective diagnosis.

Novel beta-lactam/beta-lactamase inhibitor (BIBLI) combinations are commercially available and have been used for treating carbapenem-resistant Klebsiella pneumoniae (CRKP) infections. Continuous surveillance of susceptibility profiles and resistance mechanism identification are necessary to monitor the evolution of resistance within these agents. The purpose of this study was to evaluate the susceptibility rates of ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam in CRKP isolated from patients with bloodstream infections who underwent screening for a randomized clinical trial in Brazil. Minimum inhibitory concentrations (MICs) were determined for meropenem, ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam using the gradient diffusion strip method. Carbapenemase genes were detected by multiplex real-time polymerase chain reaction. Klebsiella pneumoniae carbapenemase (KPC)-producing isolates showing resistance to any BLBLI and New Delhi Metallo-beta-lactamase (NDM)-producing isolates with susceptibility to any BLBLI isolates were further submitted for whole-genome sequencing. From a total of 69 CRKP isolates, 39 were positive for bla_KPC, 19 for bla_NDM and 11 for bla_KPC and bla_NDM. KPC-producing isolates demonstrated susceptibility rates above 94 % for all BLBLIs. Two isolates with resistance to meropenem/vaborbactam demonstrated a Gly and Asp duplication at the porin OmpK36 as well as a truncated OmpK35. All NDM-producing isolates, including KPC and NDM coproducers, demonstrated susceptibility rates to ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam of 0 %, 9.1-21.1 % and 9.1-26.3 %, respectively. Five NDM-producing isolates that presented susceptibility to BLBLIs also had porin alterations CONCLUSIONS: This study showed that, although high susceptibility rates to BLBLIs were found, KPC-2 isolates were able to demonstrate resistance probably as a result of porin mutations. Additionally, NDM-1 isolates showed susceptibility to BLBLIs in vitro.

Carbapenem-Resistant Pseudomonas Aeruginosa (CRPA) is considered as one of the high priority pathogens by the World Health Organization. As CRPA carbapenemase producers have increased worldwide, the aim of this study was to evaluate the carbapenemase prevalence in CRPA at a tertiary care hospital in Brazil". All 395 CRPA identified in the period of September 2021 to May 2024 were evaluated by multiplex real-time polymerase chain reaction (qPCR-HRM) for the following carbapenemase genes: bla_KPC, bla_NDM, bla_OXA-48-like, bla_IMP, bla_VIM,bla_SPM and bla_GES. In the first period analyzed (September to December 2021), almost 70 % of the isolates were negative for the 7 tested genes, and the bla_NDM was found in 27.3 % of the CRPA. In the following semesters there was an increase of bla_NDM as follows: January to June of 2022 = 29.8 %; July to December of 2022 = 43.8 %; January to June of 2023 = 42.4 %; July to December 2023 = 58.9 % and January to May of 2024 = 59.5 % of bla_NDM. The prevalence of the other carbapenemases remained low. These results indicated an important increase of the bla_NDM gene, overcoming the CRPA non-carbapenemase producers in our institution.

Infections due to carbapenemase-producing Enterobacterales harboring more than one carbapenemase-encoding gene spreads mainly by plasmid and transposon mobilization. Analyze the mobile genetic elements carrying bla_KPC and bla_NDM of K. pneumoniae carbapenemase co-producers (KpKN). K. pneumoniae isolates with reduced susceptibility to carbapenems were obtained from 2016 to 2023. To evaluate the genetic environment of KpKN, 22 isolates were selected for antimicrobial susceptibility testing and whole-genome sequencing (WGS). The bla_KPC-2 gene was carried mainly by IncN/IncFIB, a novel co-integrated plasmid in the Tn4401b transposon. The bla_NDM-1 was disseminated in the only two KpKN isolates recovered before 2020 by IncHI1B/IncFIB plasmid type, in the Tn3000 transposon. Noteworthy, isolates obtained since 2020 showed the bla_NDM-1 gene carried by IncA/C in an IS26-flanked pseudo-composite transposon containing ISCR1, which also had genes that confer resistance to sulfonamides, aminoglycosides, macrolides, quinolones, amphenicols, tetracyclines, rifampicin, sulfonamide, and trimethoprim. The isolates belong mainly to ST11 and ST16. The plasmid and transposon changes during the different periods could be related to higher dissemination of the bla_NDM-1 and the large number of resistance genes present in the IS26-flanked transposon may have increased the co-selection of this plasmid through the wide use of antimicrobials during the pandemic.

This study aimed to evaluate the clinical and microbiological risk factors associated with mortality in patients treated with ceftazidime-avibactam for carbapenem-resistant gram-negative bacterial infections. This multicentric prospective cohort study included hospitalized adult patients with a microbiologically confirmed infection treated with ceftazidime-avibactam for ≥48 hours. The clinical and microbiological risk factors for 30-day mortality were evaluated using a Cox regression model. Of the 193 patients evaluated from the five tertiary hospitals, 127 were included in the study. Thirty-five patients (27.5 %) died within 30 days. Infections with AmpC beta-lactamase-carrying bacteria were independently related to 30-day mortality (adjusted hazard ratio [aHR] 2.49, 95% confidence interval [CI] 1.28-4.84, P < 0.01) after adjusting for time from infection to antimicrobial prescription (P = 0.04). Further, these bacterial infections were also related to higher in-hospital mortality (aHR 2.17, 95% CI 1.24-3.78, P < 0.01). Only one patient developed resistance to ceftazidime-avibactam during treatment. Treatment with ceftazidime-avibactam had worse clinical outcomes in patients with infections with bacteria with chromosomally encoded AmpC beta-lactamase. However, these findings should be confirmed in future studies.