The role of wildlife in carrying and disseminating resistant and pathogenic bacteria has been established, yet data from wildlife in Peru are limited. This study evaluated the antibiotic resistance, presence of virulence genes, and clonality of E. coli isolated from wild birds from wetlands in Lima, Peru. Twenty-three isolates were obtained from 41 free-living birds (belonging to 15 bird species) through cloacal and feather swabs (n = 30) and fresh feces (n = 11) collected in 2021. Nineteen pulsotypes were identified by Pulsed Field Gel Electrophoresis. High resistance rates were observed for tobramycin 60.9

Background Consider this Carrion's disease (CD) is a biphasic illness—comprising acute and chronic phases—endemic to Peru and caused by Bartonella bacilliformis , a bacterium transmitted by sandflies. Despite its clinical relevance, the mechanisms underlying innate immune activation in response to B. bacilliformis remain poorly understood. Toll-like receptors (TLRs) play a central role in recognizing conserved molecular patterns present in pathogens, thereby initiating innate immune responses. The present study aimed to describe the expression patterns of TLR2 and TLR4, along with cytokine secretion profiles, during peripheral blood mononuclear cells (PBMCs) exposure to B. bacilliformis . Methods Peripheral blood mononuclear cells (PBMCs) from healthy donors were stimulated with heat-inactivated B. bacilliformis (ATCC 35685 strain), zymosan (TLR2 control), or E. coli LPS (TLR4 control). TLR2 and TLR4 gene expression was quantified by RT-qPCR at 0, 12, 24, 36, and 48 h. Cytokines were measured using a 17-plex panel. Analyses were descriptive, using non-parametric statistics. Results Results elicited measurable changes in the transcriptional expression of TLR2 and TLR4 during stimulation, with peak activation typically observed at 12 h, although in one case the maximal response was delayed to 24 h. These expression changes coincided with significant modulation of multiple cytokines, including pro-inflammatory mediators (TNF-α, IL-17, IL-12p70), Th1/Th2 cytokines (IFN-γ, IL-2, IL-5, IL-13), regulatory cytokines (IL-10), and growth factors (GM-CSF, IL-7). Conclusions This exploratory study describes the transcriptional expression patterns of TLR2 and TLR4 and the accompanying cytokine responses in PBMCs exposed to B. bacilliformis . These profiles expand current knowledge of the early innate immune signature elicited by this neglected pathogen and provide a foundation for future studies using receptor-specific functional assays. Importantly, these patterns likely reflect early innate immune response signatures rather than definitive evidence of functional receptor activation.

Tocosh, a traditional Peruvian fermented potato product, is known for its health-promoting properties, including its antioxidant, anti-inflammatory, probiotic, and antibiotic effects, which have popularized its consumption, particularly in rural areas. To gain a better understanding of its antimicrobial properties, this study aimed to perform a comprehensive whole-genome analysis and functional assessment of the Bacillus velezensis TCSH0001 strain isolated from tocosh. The isolate was identified through whole-genome sequencing using the MinION nanopore platform. AntiSMASH analysis revealed nine biosynthetic gene clusters (BGCs) potentially responsible for producing secondary metabolites with antibiotic potential. Notably, seven BGCs showed a 100% similarity to known clusters involved in the biosynthesis of polyketide synthases (PKSs) and non-ribosomal peptides (NRPSs), including difficidin, bacillibactin, bacilysin, macrolactin H, bacillaene, fengycin, and bacillomycin D. In vitro analysis revealed antimicrobial activity against S. aureus strains. In addition, RT-qPCR indicated that the expression of the baeJ (bacillaene), bmyA (bacillomycin D), and pks2A (macrolactin H) occurs predominantly during the exponential growth phase. Our results suggest that this B. velezensis strain has the capacity to produce a diverse array of bioactive compounds, supporting the traditional use of tocosh as a natural antimicrobial agent, and revealing the potential of the strain as a high NRPS producer.

Antimicrobial resistance (AMR) is a rising public health issue that compromises human, animal, and environmental health. This study assessed AMR in the swine production chain in Costa Rica using commensal E. coli as an indicator microorganism. Sampling of feces, carcass, and lymphoid tissue at exporting swine abattoirs yielded 269 presumed E. coli isolates identified by lactose-positive growth on MacConkey agar and indole production. A subset of isolates (n = 40) was confirmed as E. coli by VITEK® 2 GN testing. Antimicrobial susceptibility testing against 18 antibiotics was performed using the antibiotic disk agar diffusion method in 242 recovered isolates, and resistance to all antimicrobial classes evaluated was detected. The highest resistance levels were observed for ampicillin, cefazolin, and chloramphenicol, and notable resistance to quinolones, trimethoprim-sulfamethoxazole, and β-lactam combination agents. Resistance to clinically important drugs including ceftazidime, cefepime, aztreonam, and imipenem was observed, as well as selected β-lactamase genes. Overall, 50 distinct AMR profiles were identified, and more than half of the isolates displayed multidrug resistance. A subset of isolates (n = 30) underwent uidA PCR and ERIC-PCR analysis, revealing evidence of fecal and cross-contamination as plausible routes for dissemination of resistant bacteria during slaughter. Antimicrobial susceptibility testing by the VITEK® 2 automated system and whole-genome sequencing (WGS) of 27 isolates further characterized phenotype-genotype concordance, AMR determinants, virulence factors, serotypes, and sequence types of public health relevance. These findings provide insight into current AMR trends in the Costa Rican swine production system and highlight the role of abattoir-level contamination in AMR transmission, supporting targeted interventions to mitigate the emergence and dissemination of AMR along the pork production chain.

BackgroundConsider this Carrion's disease (CD) is a biphasic illness-comprising acute and chronic phases-endemic to Peru and caused by Bartonella bacilliformis, a bacterium transmitted by sandflies. Despite its clinical relevance, the mechanisms underlying innate immune activation in response to B. bacilliformis remain poorly understood. Toll-like receptors (TLRs) play a central role in recognizing conserved molecular patterns present in pathogens, thereby initiating innate immune responses. The present study aimed to describe the expression patterns of TLR2 and TLR4, along with cytokine secretion profiles, during peripheral blood mononuclear cells (PBMCs) exposure to B. bacilliformis.MethodsPeripheral blood mononuclear cells (PBMCs) from healthy donors were stimulated with heat-inactivated B. bacilliformis (ATCC 35685 strain), zymosan (TLR2 control), or E. coli LPS (TLR4 control). TLR2 and TLR4 gene expression was quantified by RT-qPCR at 0, 12, 24, 36, and 48 h. Cytokines were measured using a 17-plex panel. Analyses were descriptive, using non-parametric statistics.ResultsResults elicited measurable changes in the transcriptional expression of TLR2 and TLR4 during stimulation, with peak activation typically observed at 12 h, although in one case the maximal response was delayed to 24 h. These expression changes coincided with significant modulation of multiple cytokines, including pro-inflammatory mediators (TNF-α, IL-17, IL-12p70), Th1/Th2 cytokines (IFN-γ, IL-2, IL-5, IL-13), regulatory cytokines (IL-10), and growth factors (GM-CSF, IL-7).ConclusionsThis exploratory study describes the transcriptional expression patterns of TLR2 and TLR4 and the accompanying cytokine responses in PBMCs exposed to B. bacilliformis. These profiles expand current knowledge of the early innate immune signature elicited by this neglected pathogen and provide a foundation for future studies using receptor-specific functional assays. Importantly, these patterns likely reflect early innate immune response signatures rather than definitive evidence of functional receptor activation.

Introducción Escherichia coli enteroagregativa (EAEC) es un patotipo de las E. coli diarreogénicas (DEC) que causa diarrea aguda y persistente en los niños, en los pacientes con VIH y diarrea del viajero. Sin embargo, EAEC también puede ser aislado en las personas sin diarrea. El objetivo del estudio fue evaluar si la carga bacteriana de EAEC en muestras de heces se asocia con diarrea en comparación con la infección asintomática. Métodos Seleccionamos 165 muestras de heces (niños con diarrea: 80 y niños asintomáticos: 85) que previamente fueron identificados como EAEC por PCR en tiempo real para el diagnóstico de DEC a partir de E. coli aislados de coprocultivo. Extrajimos ADN utilizando el método de bromuro de cetiltrimetilamonio (CTAB) y estandarizamos un qPCR para evaluar la carga bacteriana utilizando la cepa EAEC 042. Resultados El límite de detección fue de 10 copias del gen aggR (5 bacterias)/mg de heces y la eficiencia de la reacción fue ≥93%. Encontramos una mayor carga bacteriana en los pacientes con diarrea (2.781, IC 95%: 688-6.875) bacterias/mg heces, que en niños asintomáticos (138, IC 95%: 75-306) bacterias/mg heces, incluyendo infección por patógeno único y coinfección. Entre las muestras de diarrea, la carga bacteriana fue mayor en varones que en mujeres y en niños mayores de 18 meses que menores. Conclusiones La carga de EAEC en muestras de heces es mayor en los niños con diarrea que con infección asintomática. Esta qPCR podría ser útil para estudiar el papel de la colonización en los niños de zonas endémicas con similar aislamiento en ambos grupos.

BACKGROUND:Antimicrobial resistance (AMR) has emerged as a priority for both public health and the global economy. Moreover, information on AMR is scarce, particularly in low/middle-income countries. We evaluated the direct economic cost of microorganisms and AMR. METHODS:We performed a cross-sectional study to assess the economic costs of neonatal cases diagnosed with bacteremia at the Instituto Nacional Materno Perinatal in Lima, Peru, from January 2017 to June 2018. We used cost invoices calculated by the micro-costing bottom-up approach, as well as the strain identification and antimicrobial susceptibility data, to estimate the direct costs. RESULTS:The average costs of bacteremia were US$349 (SD 403) for multidrug-resistant (MDR) strains and US$276 (SD 349) for non-MDR strains. Costs were higher for microorganisms associated with late-onset sepsis (LOS). We found that LOS, multidrug resistance and age were significantly associated with bloodstream infection (BSI) costs. Also, all microorganism groups were associated with increased costs, with the highest average costs for Acinetobacter, followed by Pseudomonas. CONCLUSIONS:In Peru, BSI costs are strongly associated with AMR. Furthermore, costs increase significantly with LOS, multidrug resistance and the patient's age. We urge health authorities to strengthen measures and strategies against the pressing threat of AMR.

INTRODUCTION:Enteroaggregative Escherichia coli (EAEC) is a pathotype of diarrheagenic E. coli (DEC) that causes acute and persistent diarrhoea in children, HIV-infected patients and travelers. However, EAEC can also be isolated in people without diarrhoea. The aim of this study was to evaluated if the EAEC bacterial load in stool samples is associated with diarrhoea in comparison with asymptomatic infection. METHODS:We selected 165 stool samples (children with diarrhoea: 80 and asymptomatic children: 85) that previously were identified as EAEC by Real-Time PCR for diagnostic of DEC from E. coli isolated from stool cultures. We extracted DNA from fecal samples using the cetyltrimethylammonium bromide (CTAB) method and standardised a qPCR to evaluate the bacterial load using EAEC strain 042. RESULTS:The detection limit of the qPCR was 10 copies ofaggR gene (5 bacterias)/mg stool and the reaction efficiency was ≥ 93%. We found a higher bacterial load in patients with diarrhoea [2781, 95% CI (688-6875) bacteria/mg feces] than in asymptomatic children [138, 95% CI (75-306) bacteria/mg feces], including samples with single pathogen infection and co-infections. Among diarrheal samples, the bacterial load was higher in boys than girls and in children older than 18 months than younger. CONCLUSIONS:EAEC load in stool samples are higher in children with diarrhoea than in asymptomatic infection. This qPCR could be useful for studying the role of colonisation in children living in endemic areas where the isolation of this pathogen is similar in both groups.

Introducción: Bartonella bacilliformis es el agente etiológico de la Enfermedad de Carrión, una enfermedad endémica en zonas rurales de Perú como Ancash y Cajamarca. A pesar de que esta enfermedad tiene una alta relevancia clínica, por su capacidad de causar síntomas graves como fiebre intensa, anemia severa y una mortalidad alta en pacientes sin tratamiento oportuno, los estudios moleculares con respecto a su variabilidad genética son escasos. Objetivo: la investigación tiene como objetivo evaluar cómo las variantes identificadas en los genes ialB, gltA y rpoB de las cepas de B. bacilliformis aisladas de la región de Ancash, impactan las estructuras de las proteínas IalB, GltA y RpoB. Método: se realizó un análisis bioinformático de estas variantes para modelar sus estructuras e identificar cambios moleculares. Resultado: En el aislado B.b-1 (Ancash, 2008), se detectaron 13 sustituciones aminoacídicas en el IalB, 4 en el GltA y 2 en el RpoB. Estas modificaciones generaron alteraciones estructurales relevantes como: Cambios en los ángulos de torsión de las proteínas, expansión del volumen de cavidad en IalB, y ruptura de enlace de hidrógeno crítico en GltA (por la sustitución Asn-->Asp). En RpoB, se observaron diferencias en su conformación. Conclusión: Los resultados del modelado indican que las variantes genéticas presentes en cepas de Bartonella bacilliformis procedentes de la región Ancash tienen un efecto estructural y/o funcional en las proteínas IalB, GltA y RpoB, con posibles implicancias en la patogenicidad, adaptación de la bacteria y manifestaciones clínicas de la enfermedad de Carrión.

Acinetobacter baumannii is an opportunistic pathogen of great clinical concern, showing high levels of resistance to several antimicrobials, including carbapenems. This study aimed to characterize carbapenem-resistant A. baumannii recovered from a tertiary care hospital (Lima, Peru) in January-February 2021 (during the coronavirus disease 2019 pandemic). Antimicrobial susceptibility was determined by VITEK-2, and the presence of carbapenem-resistance genes by PCR. All 40 A. baumannii isolates were extensively drug-resistant, showing full resistance to all antibiotics tested except ampicillin/sulbactam (95% of resistance) and colistin (10%). The bla OXA-24-like gene was detected in 90% of isolates, and the remaining 10% isolates harbored the bla OXA-23-like gene. Pulsed-field gel electrophoresis classified isolates into three different pulsotypes, grouping 8, 2, and 30 isolates, respectively. Additionally, whole-genome sequencing of two isolates of the main pulsotype revealed that they belonged to ST2 and ST2724 (international clone II) and harbored the bla TEM-1, bla OXA-66, bla OXA-72, and bla ADC-30 β-lactamase genes; mutations in gyrA and parC, aminoglycoside, tetracycline, and sulfonamide resistance genes; and a class 1 integron (In439) containing aac(6')-Ib', catB8, and aadA1 located inside the AbGRI3 genomic resistance island. These findings highlight the presence of highly resistant and clonally related ST2 of A. baumannii and their relationship with genomes of ST2 of South America. IMPORTANCE:Acinetobacter baumannii is a critical pathogen known for causing severe infections in hospitalized patients and for its remarkable ability to develop resistance to multiple antibiotics, including last-line treatments such as carbapenems. In Latin America, data on the genetic background and spread of these resistant strains remain limited. Our study provides a detailed molecular and genomic characterization of extensively drug-resistant A. baumannii isolates collected from a Peruvian hospital during the coronavirus disease 2019 pandemic. We identified a predominant clone belonging to international clone II, which carried multiple resistance genes and a complex resistance island. These findings raise public health concerns, as they highlight the silent spread of high-risk clones in regions with limited surveillance capacity. By contributing valuable local genomic data, our study supports global efforts to track antimicrobial resistance and underscores the urgent need to strengthen molecular monitoring of hospital-associated pathogens also in low- and middle-income countries.

The emergence and spread of third-/fourth-generation cephalosporin and/or carbapenem-resistant Acinetobacter baumannii have become a significant global public health concern, making new treatment alternatives necessary. Thus, the present study aimed to assess in vitro cefiderocol activity against clinical isolates of A. baumannii and analyze their relationship with extended-spectrum β-lactamases (ESBLs) and carbapenemases. Ninety-five A. baumannii clinical isolates were included in the study. Susceptibility to 12 antimicrobial agents was established by automated methods and/or disk diffusion, while that of colistin was determined following microdilution and that of cefiderocol by microdilution using iron-depleted broth. The presence of blaCTX-M, blaPER, blaVEB, blaGES, blaVIM, blaIMP, blaIMI, blaKPC, blaNDM, blaOXA-23G, blaOXA-24G, blaOXA-48G, and blaOXA-58G was established by PCR. The results showed extremely high levels of resistance (>80%) to all the tested antibacterial agents except colistin (11.6%) and cefiderocol (Clinical and Laboratory Standards Institute [CLSI]: 0%; US Food and Drug Administration [FDA]: 1.1%). Following FDA criteria, 22.1% of isolates were intermediate to cefiderocol, with 68.4% of isolates surpassing the European Committee on Antimicrobial Susceptibility Testing epidemiological cut off. Seven colistin-resistant isolates were only susceptible to cefiderocol following CLSI breakpoints, four of them qualifying as cefiderocol-intermediate following FDA breakpoints. No association between the presence of ESBLs or carbapenemases and cefiderocol minimum inhibitory concentration levels was observed. The present results show the potential utility of cefiderocol in the treatment of A. baumannii infections, highlighting the need for judicious use and continuous surveillance to prevent the emergence of cefiderocol-resistant A. baumannii clones.IMPORTANCEAntibiotic resistance is a silent pandemic challenging the treatment of infectious diseases worldwide, but also other medical practices, as, for instance, organ transplantation procedures. In Peru, current levels of antimicrobial resistance are worrisome. In this scenario, we have determined the in vitro activity of cefiderocol against a series of Acinetobacter baumannii exhibiting high levels of resistance to commonly used antibiotics. This activity is independent of the presence of the most common extended-spectrum beta-lactamases or carbapenemases. Obtained results showed the potential of cefiderocol to become an alternative for the treatment of this type of microorganism, but the high number of isolates bordering the considered breakpoint, despite the lack of use of cefiderocol in the country, also shows the need for a prudent use of this antibiotic to maximize its utility while minimizing the selection of resistant isolates.

Escherichia coli sequence type 131:H:22 is a consequential lineage of extraintestinal pathogenic E. coli, associated with human pyelonephritis and sepsis. We report the transmission of avian pathogenic E. coli in a parrot rehabilitation center in Brazil and the presence of a high-risk zoonotic lineage of extraintestinal pathogenic E. coli sequence type 131-H22.

Introduction: Frequent consumption of red and processed meat is associated with alterations in the gastrointestinal microbiome. Among the bacteria involved, Fuso-bacterium nucleatum (FN) stands out due to its link with inflammation and colorectal cancer, making it a key microorganism for studying the impact of Western diets on the intestinal health of older adults. Objective: To determine the association between the consumption of meat and meat products and fecal FN levels in a specific population of older adults in Lima, Peru. Materials and Methods: In this cross-sectional analytical study, 111 older adults (>= 60 years) attending a senior care center in Lima, Peru, were recruited. The study was conducted between August and November 2024. A food frequency questionnaire (FFQ) focused on the consumption of meats, organ meats, offal, and industrialized meat products was administered. Additionally, fecal FN levels were quantified using qPCR. Results: Fecal levels of FN were detected in 20% of participants, with values ranging from 4.4 to 6.5 log10 copies per gram of feces (5.23 +/- 0.61 log10 copies/g). Regarding the FFQ, high consumption of chicken and low intake of other meats were identified. Chicken feet were the most frequently consumed offal weekly (75.7%) and were the only food significantly associated with higher FN abundance (p=0.027). No statistically significant association was found between FN levels and the other evaluated variables. Conclusion: This is the first study in Peru to assess the prevalence of FN in older adults. Only one meat-derived food item was associated with its levels. Further studies are needed to clarify the relationship between diet and FN levels across different population groups.

Background:The bla SCO-1 gene, which codes for a carbenicillinase, is an uncommon β-lactamase. To the best of our knowledge, we report the first instance of a Klebsiella pneumoniae clinical high-risk isolate carrying bla SCO-1 in Peru. Objectives:To characterize a K. pneumoniae clinical isolate carrying bla SCO-1 in Peru, isolated from a tertiary care hospital in Lima, Peru. Methods:Susceptibility to amoxicillin/clavulanic acid, amoxicillin/sulbactam, piperacillin/tazobactam, aztreonam, ceftriaxone, cefotaxime, ceftazidime, ceftazidime/avibactam, cefepime, imipenem, meropenem, ciprofloxacin, trimethoprim/sulfamethoxazole, gentamicin, amikacin and tigecycline was determined using the Kirby-Bauer disc diffusion method. Detection of bla SCO-1 was established by Illumina WGS and bioinformatic analyses. All the publicly available genomes from K. pneumoniae carrying bla SCO-1 from the American continent were downloaded from the NCBI Isolates browser for assessment of phylogenetic comparisons. Results:The isolate showed resistance to all the tested antibiotics except for ceftazidime/avibactam, carbapenems and tigecycline. Illumina WGS showed the presence of bla SCO-1 and bla OXA-1, bla SHV-28, bla TEM-1, bla CTX-M-15, as well as genes associated with resistance to quinolones, fosfomycin, aminoglycosides, sulphonamides, trimethoprim and phenicols. Moreover, the isolate was ST307, a high-risk clone of K. pneumoniae usually associated with bla CTX-M-15 and/or carbapenemases. Notwithstanding, the latter were not found on this isolate. Phylogenetic relationships were established by comparisons with 19 K. pneumoniae genomes carrying bla SCO-1 from other countries in the Americas, revealing at least three different clades. Conclusions:This study highlights the importance of genomic surveillance of uncommon antimicrobial resistance genes such as bla SCO-1, which might contribute to further antimicrobial resistance levels in this country.

Five carbapenem-resistant P. aeruginosa isolates were obtained from 33 adult Guanay Cormorants from Isla Pescadores, Lima, Peru. Four isolates had a similar antibiotic susceptibility profile and their carbapenem resistance was attributed to mutations in OprD porin; whilst the last isolate carried both blaVIM (encoded within a Class 1 integron) and blaIMP. Moreover, the VIM/IMP co-producer belongs to ST111, considered as a high-risk clone. The other isolates could not be identified by MLST since amplification of mutL, aroE, and acsA could not be achieved. The exoA and exoT genes were present in all isolates, while the VIM/IMP isolate also carried exoS and exoY but neither exoU nor algD. BOX-PCR showed that the VIM/IMP isolate was not clonally related to the other four. These findings highlight the importance of surveillance and characterisation of carbapenem-resistant bacteria from environmental sources in Peru.

Background:Common identification techniques do not differentiate among members of the Acinetobacter calcoaceticus-baumannii (ACB) complex, and the presence of non-baumannii Acinetobacter is often misinterpreted. The bla OXA-51 gene is located within the chromosome of Acinetobacter baumannii. Despite its plasmid dissemination to other members of the genus, it may be considered in initial species screening. Thus, this study aimed to determine the presence of bla OXA-51-negative Acinetobacter spp. as a cause of infection in Peru. Methods:Two hundred ninety-eight ACB complex isolates from different regions of Peru were isolated between January 2018 and March 2024. Of these, 272 and 25 were confirmed as hospital-acquired and community infections, respectively. The presence of bla OXA-51 was determined by polymerase chain reaction, and the susceptibility levels to 12 antimicrobial agents were determined. Results:The results showed that 38 (12.7%) isolates were bla OXA-51-negative. These isolates were frequent among community infections (13/25, p < 0.0001), often causing urine infections. They showed significantly lower levels of resistance to almost all antimicrobial agents tested, and most of them were recovered from regions outside metropolitan Lima. Conclusion:A relevant number of infections by non-baumannii Acinetobacter species in Peru is suggested, highlighting the need for systematic identification of these species in the country.

Objectives:To determine the activity of cefiderocol against 101 Peruvian Pseudomonas aeruginosa isolates. Methods:Carbapenem- and/or third- and fourth-generation cephalosporin-resistant P. aeruginosa clinical isolates were isolated in nine Peruvian health centres. Antibiotic susceptibility was established by automated methods and/or disc diffusion (10 antimicrobial agents), colistin agar test (colistin) and microdilution (cefiderocol). The presence of bla PER, bla CTX-M, bla GES, bla KPC, bla IMI, bla IMP, bla NDM, bla OXA-23, bla OXA-24, bla OXA-48, bla OXA-58, bla VIM and oprD was established by PCR; bla CTX-M and oprD were sequenced. The levels of antimicrobial resistance ranged from 20.8% (colistin) to 97.0% (meropenem). Results:The MIC of cefiderocol ranged from  ≤ 0.06 to 8 mg/L (one isolate). Cefiderocol resistance rates were 1.0% (according to the FDA and EUCAST) and 0% according to CLSI, whereas 14.9% and 1.0% of isolates were classified as cefiderocol-intermediate according to FDA and CLSI, respectively. CTX-M-131 and GES, and IMP and VIM were the most frequent ESBLs and carbapenemases, respectively. The presence of oprD mutations was tested in 47 carbapenem-resistant isolates, 23 with oprD-inactivating mutations as the sole underlying mechanism. Although no specific association was found between the presence of ESBLs and carbapenemases with cefiderocol resistance, carbapenemase-producing isolates tended to present slightly higher cefiderocol MIC values. The cefiderocol-resistant isolate did not present ESBLs or carbapenemases, showing only an oprD-inactivating mutation. Conclusions:Cefiderocol showed excellent activity against P. aeruginosa, irrespective of the presence of ESBLs and/or carbapenemases. The high number of isolates bordering cefiderocol-resistant levels suggests the need for cautious use and continuous surveillance of this antibiotic.

Objectives:To evaluate the synergistic activity of ampicillin/sulbactam plus ceftazidime/avibactam in a collection of carbapenem-resistant Acinetobacter baumannii (CR-Ab) from different regions in Peru. Materials and methods:One hundred and eighty-four CR-Ab isolates were included in this study. They were identified by amplification of bla OXA-51 and confirmed by MALDI-TOF (matrix-assisted laser desorption ionization time of flight) mass spectrometry and 16S rRNA sequencing. Susceptibility to ampicillin/sulbactam and carbapenems was determined by the disc diffusion method. Synergy was assessed using discs containing ampicillin/sulbactam and ceftazidime/avibactam. The EDTA-disc synergy test was used to screen metallo-β-lactamase-producing isolates, and in isolates showing synergy, the presence of bla NDM was confirmed by PCR. Statistical analysis was performed using Fisher's exact test. Results:High levels of resistance to ampicillin/sulbactam were found in the study. Thus, 1.1% (2/184), 11.4% (21/184) and 87.5% (161/184) of isolates were classified as susceptible, intermediate and resistant to ampicillin/sulbactam, respectively. Synergistic activity was observed in 97.2% of the non-susceptible CR-Ab isolates. The presence of metallo-β-lactamase producers (all bla NDM) was observed in three isolates (1.6%). Conclusions:These findings demonstrate high levels of synergistic activity between ampicillin/sulbactam and ceftazidime/avibactam and their potential use as a treatment for CR-Ab.

Pseudomonas aeruginosa is an opportunistic pathogen commonly associated with infections in hospitalized and immunocompromised patients due to its virulence and antimicrobial resistance. In the poultry industry, it has been associated with hatchery mortality. This study aimed to characterize P. aeruginosa isolated from pipped eggs, one-day-old chicks, and broiler carcasses obtained from a slaughterhouse in São Paulo state, Brazil. Nineteen strains of P. aeruginosa were selected and their virulence genes were amplified via PCR. Clonality analysis was performed using BOX-PCR, and three strains were selected for whole-genome sequencing (WGS). All isolates carried aprA, plcH, plcN, lasA, lasB, lasI, lasR, rhlAB, and phzH. The exoA gene was detected in 73.7% of strains, while algD was present in 21.1%. The exoY and exoT genes were present in 94.7% of strains (18/19), whereas exoS was present in 47.4% (9/19). None of the isolates harbored the exoU gene. BOX-PCR and phylogenetic analyses revealed diverse clonal patterns. The sequenced strains were classified as O3 ST116, O2 ST1649, and O3 ST1744. The presence of virulence and antimicrobial resistance determinants in poultry-associated strains underscores the need for surveillance, as these isolates may represent a source for transmission of P. aeruginosa to humans. Our findings highlight the importance of monitoring P. aeruginosa within poultry production and emphasize the value of genomic approaches to understand its diversity, evolution, and public health risks.

Quinolone resistance has been largely related to the presence of specific point mutations in chromosomal targets, with an accessory role of impaired uptake and enhanced pump-out. Meanwhile the relevance of transferable mechanisms of resistance able to protect the target of pump-out or inactivate quinolones has been increasingly reported since 1998. Nevertheless, bacteria have other strategies and mechanisms allowing them to survive and even proliferate in the presence of quinolones, which might be qualified as resistance or resilience mechanisms. These include decreasing levels of quinolone target production, transient amoeba protection, benthonic lifestyle, nutrient-independent slow growth, activation of stringent response, inactivation or degradation of quinolones as well as apparently unrelated or forgotten chromosomal mutations. These mechanisms have been largely overlooked, either because of the use of classical approaches to antibiotic resistance determination or due to the low increase in final minimum inhibitory concentration levels. This article is devoted to a review of a series of these mechanisms.