Impact of chromosomally encoded resistance mechanisms and transferable ß-lactamases on the activity of cefiderocol and innovative ß-lactam/ß-lactamase inhibitor combinations against Pseudomonas aeruginosa.

OBJECTIVES: We aimed to compare the stability of the newly developed ß-lactams (cefiderocol) and ß-lactam/ß-lactamase inhibitor combinations (ceftazidime/avibactam, ceftolozane/tazobactam, aztreonam/avibactam, cefepime/taniborbactam, cefepime/zidebactam, imipenem/relebactam, meropenem/vaborbactam, meropenem/nacubactam and meropenem/xeruborbactam) against the most clinically relevant mechanisms of mutational and transferable ß-lactam resistance in Pseudomonas aeruginosa. METHODS: We screened a collection of 61 P. aeruginosa PAO1 derivatives. Eighteen isolates displayed the most relevant mechanisms of mutational resistance to ß-lactams. The other 43 constructs expressed transferable ß-lactamases from genes cloned in pUCP-24. MICs were determined by reference broth microdilution. RESULTS: Cefiderocol and imipenem/relebactam exhibited excellent in vitro activity against all of the mutational resistance mechanisms studied. Aztreonam/avibactam, cefepime/taniborbactam, cefepime/zidebactam, meropenem/vaborbactam, meropenem/nacubactam and meropenem/xeruborbactam proved to be more vulnerable to mutational events, especially to overexpression of efflux operons. The agents exhibiting the widest spectrum of activity against transferable ß-lactamases were aztreonam/avibactam and cefepime/zidebactam, followed by cefepime/taniborbactam, cefiderocol, meropenem/xeruborbactam and meropenem/nacubactam. However, some MBLs, particularly NDM enzymes, may affect their activity. Combined production of certain enzymes (e.g. NDM-1) with increased MexAB-OprM-mediated efflux and OprD deficiency results in resistance to almost all agents tested, including last options such as aztreonam/avibactam and cefiderocol. CONCLUSIONS: Cefiderocol and new ß-lactam/ß-lactamase inhibitor combinations show promising and complementary in vitro activity against mutational and transferable P. aeruginosa ß-lactam resistance. However, the combined effects of efflux pumps, OprD deficiency and efficient ß-lactamases could still result in the loss of all therapeutic options. Resistance surveillance, judicious use of new agents and continued drug development efforts are encouraged.

Impact of transferable ß-lactamases and intrinsic AmpC amino acid substitutions on the activity of cefiderocol against wild-type and iron uptake-deficient mutants of Pseudomonas aeruginosa.

OBJECTIVES: We aimed to analyse the interplay between impaired iron uptake and ß-lactamases on cefiderocol resistance in Pseudomonas aeruginosa. METHODS: Thirty-one transferable ß-lactamases and 16 intrinsic P. aeruginosa AmpC (PDC) variants were cloned and expressed in wild-type (PAO1) and iron uptake-deficient (PAO ΔpiuC) P. aeruginosa backgrounds. MICs of cefiderocol and antipseudomonal ß-lactams were determined by reference broth microdilution. RESULTS: Relative to PAO1, deletion of piuC caused a specific 16-fold decrease in cefiderocol activity but negligible effects on the activity of other ß-lactams. Among transferable ß-lactamases, SHV-12, KPC Ω-loop mutants, NDMs and OXA-15 showed cefiderocol MIC values above the clinical breakpoint (2 mg/L) when expressed in PAO1. When expressed in PAO ΔpiuC, these and the transformants harbouring PER-1, VEB-1, KPC-2, KPC-3, VIM-1, CMY-2, OXA-2 and OXA-14 showed increased MIC values from 16 to >256 mg/L. The PDC variants carrying the Ω-loop changes ΔP215-G222 (PDC-577), E219K (PDC-221 and PDC-558) and the H10 helix change L293P (PDC-219) had the greatest impact on cefiderocol resistance, with MICs of 2-4 mg/L in PAO1 and of up to 32-64 mg/L in PAO ΔpiuC. Widespread enzymes such as GES, CTX-M-9, CTX-M-15, VIM-2-like enzymes, IMPs, DHA-1, FOX-4, OXA-10, OXA-48 and the other PDC variants tested had weaker effects on cefiderocol resistance. CONCLUSION: We add evidence about the effect of the interplay between iron uptake and ß-lactamases on the acquisition of cefiderocol resistance in P. aeruginosa. These findings may help to anticipate the emergence of resistance and optimize the use of cefiderocol against P. aeruginosa infections.

Fatal Case of Nosocomial Legionella pneumophila Pneumonia, Spain, 2018.

A nosocomial case of Legionella pneumophila pneumonia likely caused by a serogroup 3 strain was detected by a urinary antigen test in Spain in 2018. Although Legionella bacteria could not be isolated from respiratory samples, molecular methods implicated the sink faucet of the patient's room as the probable infection source.

Activity of cefiderocol and innovative ß-lactam/ß-lactamase inhibitor combinations against isogenic strains of Escherichia coli expressing single and double ß-lactamases under high and low permeability conditions.

OBJECTIVES: To analyse the impact of the most clinically relevant ß-lactamases and their interplay with low outer membrane permeability on the activity of cefiderocol, ceftazidime/avibactam, aztreonam/avibactam, cefepime/enmetazobactam, cefepime/taniborbactam, cefepime/zidebactam, imipenem/relebactam, meropenem/vaborbactam, meropenem/xeruborbactam and meropenem/nacubactam against recombinant Escherichia coli strains. METHODS: We constructed 82 E. coli laboratory transformants expressing the main ß-lactamases circulating in Enterobacterales (70 expressing single ß-lactamase and 12 producing double carbapenemase) under high (E. coli TG1) and low (E. coli HB4) permeability conditions. Antimicrobial susceptibility testing was determined by reference broth microdilution. RESULTS: Aztreonam/avibactam, cefepime/zidebactam, cefiderocol, meropenem/xeruborbactam and meropenem/nacubactam were active against all E. coli TG1 transformants. Imipenem/relebactam, meropenem/vaborbactam, cefepime/taniborbactam and cefepime/enmetazobactam were also highly active, but unstable against most of MBL-producing transformants. Combination of ß-lactamases with porin deficiency (E. coli HB4) did not significantly affect the activity of aztreonam/avibactam, cefepime/zidebactam, cefiderocol or meropenem/nacubactam, but limited the effectiveness of the rest of carbapenem- and cefepime-based combinations. Double-carbapenemase production resulted in the loss of activity of most of the compounds tested, an effect particularly evident for those E. coli HB4 transformants in which MBLs were present. CONCLUSIONS: Our findings highlight the promising activity that cefiderocol and new ß-lactam/ß-lactamase inhibitors have against recombinant E. coli strains expressing widespread ß-lactamases, including when these are combined with low permeability or other enzymes. Aztreonam/avibactam, cefiderocol, cefepime/zidebactam and meropenem/nacubactam will help to mitigate to some extent the urgency of new compounds able to resist MBL action, although NDM enzymes represent a growing challenge against which drug development efforts are still needed.

In vitro development of imipenem/relebactam resistance in KPC-producing Klebsiella pneumoniae involves multiple mutations including OmpK36 disruption and KPC modification.

OBJECTIVES: In order to inform and anticipate potential strategies aimed at combating KPC-producing Klebsiella pneumoniae infections, we analysed imipenem/relebactam and ceftazidime/avibactam single-step mutant frequencies, resistance development trajectories, differentially selected resistance mechanisms and their associated fitness cost using four representative high-risk K. pneumoniae clones. METHODS: Mutant frequencies and mutant preventive concentrations were determined using agar plates containing incremental concentrations of ß-lactam/ß-lactamase inhibitor. Resistance dynamics were determined through incubation for 7 days in 10 mL MH tubes containing incremental concentrations of each antibiotic combination up to their 64 × baseline MIC. Two colonies per strain from each experiment were characterized by antimicrobial susceptibility testing, whole genome sequencing and competitive growth assays (to determine in vitro fitness). KPC variants associated with imipenem/relebactam resistance were characterized by cloning and biochemical experiments, atomic models and molecular dynamics simulation studies. RESULTS: Imipenem/relebactam prevented the emergence of single-step resistance mutants at lower concentrations than ceftazidime/avibactam. In three of the four strains evaluated, imipenem/relebactam resistance development emerged more rapidly, and in the ST512/KPC-3 clone reached higher levels compared to baseline MICs than for ceftazidime/avibactam. Lineages evolved in the presence of ceftazidime/avibactam showed KPC substitutions associated with high-level ceftazidime/avibactam resistance, increased imipenem/relebactam susceptibility and low fitness costs. Lineages that evolved in the presence of imipenem/relebactam showed OmpK36 disruption, KPC modifications (S106L, N132S, L167R) and strain-specific substitutions associated with imipenem/relebactam resistance and high fitness costs. Imipenem/relebactam-selected KPC derivatives demonstrated enhanced relebactam resistance through important changes affecting relebactam recognition and positioning. CONCLUSIONS: Our findings anticipate potential resistance mechanisms affecting imipenem/relebactam during treatment of KPC-producing K. pneumoniae infections.

Hepatitis A outbreak in Australia linked to imported Medjool dates, June-September 2021.

Abstract: Imported, minimally processed food products have been historically associated with several hepatitis A outbreaks in Australia. Here, we report the first known hepatitis A outbreak in Australia linked to consumption of imported fresh Medjool dates. Between June and September 2021, six genetically identical hepatitis A cases were notified in New South Wales and the Australian Capital Territory. All cases reported date consumption during their exposure period. The implicated dates were positive for hepatitis A virus (HAV) by reverse transcription polymerase chain reaction. Rapid detection of this outbreak and the swift implementation of control measures was facilitated by two key factors. Firstly, Australian international border closures implemented in response to the COVID-19 pandemic meant that a common locally-acquired, as opposed to travel-acquired, source for cases was strongly suspected. Secondly, prompt awareness of a hepatitis A outbreak in the United Kingdom (which was found to be associated with date consumption) allowed for early hypothesis generation and investigation. This paper details the epidemiological and microbiological factors involved in this outbreak investigation and the actions taken to mitigate public health risk.

Forensic comparison of soils by bacterial community DNA profiling.

This preliminary investigation has shown that a soil microbial community DNA profile can be obtained from the small sample of soil recovered from the sole of a shoe, and from soil stains on clothing. We have also shown that these profiles are representative of the site of collection and therefore could potentially be used as associative evidence to prove a link between suspects and crime scenes. Soil community profiles were obtained using the T-RFLP fingerprinting method that uses fluorescent primer technology and semi-automated analysis techniques similar to those used in human DNA profiling in forensic laboratories.

Síndrome cardiorrenal / Cardiorenal syndrome

Resumen La insuficiencia cardiaca origina inicialmente una lesión miocárdica que conlleva remodelamiento ventricular, lo cual induce a la activación de mecanismos compensadores, entre los cuales el riñón es pieza fundamental ya que regula la homeostasis hidroelectrolítica y así el volumen circulante. El sistema nervioso simpático y el sistema renina-angiotensina-aldosterona aportan una retención de sodio y agua que afecta negativamente la función cardiaca y conduce a compromiso cardiovascular, miocárdico y renal; de allí nace la definición clínica de síndrome cardiorrenal que se clasifica de acuerdo con su forma de presentación y componentes fisiopatológicos. Esto motivó la definición y conceptualización del síndrome cardiorrenal, que incluye interacciones bidireccionales, en la que alteraciones, tanto agudas como crónicas de cualquier órgano, pueden afectar de manera funcional o estructural la función ventricular, la renal o ambas.

Abstract Heart failure initially causes myocardial damage that leads to ventricular remodelling. This, in turn, leads to activation of compensatory mechanisms where the kidney plays a fundamental role, as it regulates electrolyte homeostasis and thus the circulating volume. The sympathetic nervous system and the renin angiotensin-aldosterone system lead to the retention of sodium and water, which adversely affects cardiac function. This leads to cardiovascular, renal and myocardial compromise, or a cardiorenal syndrome, which is classified according to its presentation and pathophysiological components. The definition and conceptualization of cardiorenal syndrome includes two-way interactions, where acute and chronic changes of any organ can functionally or structurally affect the ventricular and/or renal function

Predictive equations for maximum heart rate. Myth or reality / Ecuaciones predictivas para la frecuencia cardiaca máxima. Mito o realidad

Abstract: Introduction and objective: Maximum heart rate (MHR) is essential to establish the effort, intensity and strategies for physical activity. For this, there are more than 40 formulas; among the best known are 220-Age and Tanaka. The objective of this research is to determine the validity and effectiveness of the equations for MHR. Material and methods: Observational, descriptive and transversal study with a sample of 300 participants (181 women and 119 men) with a mean age of 26 ± 10 years. For the development of this research, we used anthropometry, vital signs, Borg scale and questionnaire for cardiovascular risk factors and a stress test and compare the data with 25 equations of MHR. Results: Maximum heart rate by stress test of the 300 participants was 179.6 ± 15 beats per minute; regarding 25 equations, was observed an overestimation up to 19 beats per minute. Only the formulas of Morris and Graettinger scored less than 4 beats per minute apart to stress test. Conclusions: No one is recommended equations evaluated for their significant difference in the stress test; especially 220-edad, Hossack y Bruce, Cooper and Lester whose difference mean were above 14 beats per minute (p = 0.000). The equation of Morris (p = 0.380) no were found significant differences and were the most successful to estimate the MHR for a minimum difference compared to a stress test.

Resumen: Introducción y objetivo: La frecuencia cardiaca máxima (FCM) es un parámetro esencial para esTablecer el esfuerzo, intensidad y estrategias de la actividad física. Para ello, existen más de 40 fórmulas; entre las más conocidas son 220-edad y Tanaka. El objetivo de la presente investigación es determinar la validez y efectividad de las ecuaciones para la FCM. Material y métodos: Estudio observacional, descriptivo y transversal con 300 participantes (181 mujeres y 119 hombres), de edad promedio de 26 ± 10 años. Para el desarrollo de esta investigación, se obtuvo antropometría, signos vitales, escala de Borg, cuestionario para factores de riesgo cardiovascular y realización de prueba de esfuerzo para comparar datos con 25 ecuaciones de FCM. Resultados: La FCM por prueba de esfuerzo en los 300 participantes fue de 179.6 ± 15 latidos por minuto; en cuanto a las 25 ecuaciones, se observó una sobreestimación hasta en 19 latidos por minuto y sólo las fórmulas de Morris y Graettinger obtuvieron menos de cuatro latidos por minuto de diferencia a la prueba de esfuerzo. Conclusiones: No se recomienda alguna de las ecuaciones evaluadas por su diferencia significativa respecto a la prueba de esfuerzo; especialmente 220-edad, Hossack y Bruce, Cooper y Lester cuya diferencia de media estuvo por encima de 14 latidos por minutos (p = 0.000). Para la ecuación de Morris (p = 0.380) no se encontraron diferencias significativas y fue la más acertada para estimar la FCM comparada con una prueba de esfuerzo.

Frecuencia de amputaciones por pie diabético en un área de salud / Amputation rate as caused by diabetic foot in a primary health care district

Se realizó un estudio de la frecuencia de amputaciones de miembros inferiores por síndrome del pie diabético en el área de salud “Ignacio Agramonte” de la ciudad de Camaguey, desde enero de 1998 a diciembre de 2003 para determinar la incidencia de amputaciones de miembros inferiores mediante la caracterización de los pacientes amputados. La incidencia de amputaciones por pie diabético se presentó en nueve pacientes, predominaron en las mujeres mayores de 50 años ,el nivel de amputación más frecuente fue el del pie vinculado al diabético mixto en cinco pacientes (55.5 por ciento).El tiempo de evolución de la diabetes mellitus mayor de 15 años constituyó un importante factor de riesgo, otros que favorecieron las amputaciones fueron la hiperglicemia, la neuropatía periférica, la oclusión de las arterias de las piernas, el sedentarismo, la hipertensión arterial y las amputaciones previas. La oclusión de las arterias de las piernas constituyó un factor de riesgo importante, se manifestó en ocho pacientes (88.8 por ciento), de ellos siete (81.5 por ciento) del total de pacientes con oclusiones arteriales presentaron un patrón oclusivo distal, los cuales sufrieron amputaciones a nivel de la pierna y el pie