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[This corrects the article DOI: 10.3389/fmolb.2020.592747.].
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Temperature is a crucial variable that every living organism, from bacteria to humans, need to sense and respond to in order to adapt and survive. In particular, pathogenic bacteria exploit host-temperature sensing as a cue for triggering virulence gene expression. Here, we have identified and characterized two integral membrane thermosensor histidine kinases (HKs) from Gram-positive pathogens that exhibit high similarity to DesK, the extensively characterized cold sensor histidine kinase from Bacillus subtilis. Through in vivo experiments, we demonstrate that SA1313 from Staphylococcus aureus and BA5598 from Bacillus anthracis, which likely control the expression of putative ATP binding cassette (ABC) transporters, are regulated by environmental temperature. We show here that these HKs can phosphorylate the non-cognate response regulator DesR, partner of DesK, both in vitro and in vivo, inducing in B. subtilis the expression of the des gene upon a cold shock. In addition, we report the characterization of another DesK homolog from B. subtilis, YvfT, also closely associated to an ABC transporter. Although YvfT phosphorylates DesR in vitro, this sensor kinase can only induce des expression in B. subtilis when overexpressed together with its cognate response regulator YvfU. This finding evidences a physiological mechanism to avoid cross talk with DesK after a temperature downshift. Finally, we present data suggesting that the HKs studied in this work appear to monitor different ranges of membrane lipid properties variations to mount adaptive responses upon cooling. Overall, our findings point out that bacteria have evolved sophisticated mechanisms to assure specificity in the response to environmental stimuli. These findings pave the way to understand thermosensing mediated by membrane proteins that could have important roles upon host invasion by bacterial pathogens.
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Antecedentes y objetivo: La procalcitonina (PCT) puede ayudar al diagnóstico precoz de las infecciones bacterianas y estimar la respuesta obtenida. El objetivo es estudiar el valor de la PCT para el diagnóstico de la neumonía asociada a ventilación mecánica (NAV). Pacientes y método: Estudio prospectivo y observacional, realizado durante 18 meses, en una Unidad de Cuidados Intensivos (UCI) polivalente. Se incluyeron mayores de 18 años, con sospecha de neumonía luego de 48h de ventilación mecánica (VM). Se recogieron: datos demográficos, patología de ingreso, motivo de inicio de la VM, escalas de gravedad (APACHE II, SAPS II y SOFA), proteína C reactiva (PCR) y PCT. Al momento de la sospecha de NAV: precoz o tardía, severidad radiológica, presencia de shock séptico, SOFA, PCR, PCT y microbiología. Resultados: Se incluyeron 91 pacientes con sospecha de NAV. La media de edad fue de 42 (17,76) años y la de internación en la UCI fue de 18,59 (11,69) días. La NAV fue confirmada en 74 pacientes, de los cuales 19 (25,7%) presentaron shock séptico. La mortalidad fue del 28,4%. No hubo diferencias significativas de la PCT en los pacientes que presentaron NAV y los que no la presentaron (p=0,449). Cuando se compararon los pacientes sin NAV, con NAV y NAV con shock, la mediana de PCT fue de 0,38 (IC95%: 0,22-1,90), 0,56 (IC95%: 0,19-1,77) y 1,93 (IC95%: 0,38-10,07), respectivamente (p=0,169). Conclusiones: En nuestro trabajo la PCT no demostró utilidad para el diagnóstico de la NAV
Background and objective: Procalcitonin (PCT) can help the early diagnosis of bacterial infections and estimate the response obtained. The objective is to study the value of PCT for the diagnosis of ventilator-associated pneumonia (VAP). Patients and method: Prospective and observational study, carried out for 18 months, in a polyvalent Intensive Care Unit (ICU). Those included were over 18 years of age, with suspected pneumonia after 48h of mechanical ventilation (MV). Collected were demographic characteristics; admission pathology; reason for beginning MV; gravity scores (APACHE II, SAPS II and SOFA); C-reactive protein (CRP) and PCT. At the time of suspicion of VAP: early or late, radiological severity, presence of septic shock, SOFA, CRP, PCT and microbiology. Results: Ninety-one patients with suspected VAP were included. The mean age was 42 (17.76) and that of hospitalisation in the ICU was 18.59 (11.69) days. VAP was confirmed in 74 patients, of which 19 (25.7%) presented septic shock. The mortality was 28.4%. There were no significant differences of the PCT in the patients who presented VAP versus those who did not present VAP (P=.449). When patients without VAP, with VAP and VAP with shock, were compared, the PCT median was 0.38 (CI95%: 0.22-1.90), 0.56 (CI95%: 0.19-1.77) and 1.93 (CI95%: 0.38-10.07), respectively (P=.169). Conclusions: In our study, PCT did not prove useful for the diagnosis of VAP
Asunto(s)
Humanos , Masculino , Adulto , Persona de Mediana Edad , Femenino , Polipéptido alfa Relacionado con Calcitonina/administración & dosificación , Diagnóstico Precoz , Respiración Artificial/efectos adversos , Neumonía Asociada al Ventilador/diagnóstico , Infecciones Bacterianas/diagnóstico , Estudios Prospectivos , Biomarcadores , Neumonía Asociada al Ventilador/tratamiento farmacológicoRESUMEN
BACKGROUND AND OBJECTIVE: Procalcitonin (PCT) can help the early diagnosis of bacterial infections and estimate the response obtained. The objective is to study the value of PCT for the diagnosis of ventilator-associated pneumonia (VAP). PATIENTS AND METHOD: Prospective and observational study, carried out for 18 months, in a polyvalent Intensive Care Unit (ICU). Those included were over 18 years of age, with suspected pneumonia after 48h of mechanical ventilation (MV). Collected were demographic characteristics; admission pathology; reason for beginning MV; gravity scores (APACHE II, SAPS II and SOFA); C-reactive protein (CRP) and PCT. At the time of suspicion of VAP: early or late, radiological severity, presence of septic shock, SOFA, CRP, PCT and microbiology. RESULTS: Ninety-one patients with suspected VAP were included. The mean age was 42 (17.76) and that of hospitalisation in the ICU was 18.59 (11.69) days. VAP was confirmed in 74 patients, of which 19 (25.7%) presented septic shock. The mortality was 28.4%. There were no significant differences of the PCT in the patients who presented VAP versus those who did not present VAP (P=.449). When patients without VAP, with VAP and VAP with shock, were compared, the PCT median was 0.38 (CI95%: 0.22-1.90), 0.56 (CI95%: 0.19-1.77) and 1.93 (CI95%: 0.38-10.07), respectively (P=.169). CONCLUSIONS: In our study, PCT did not prove useful for the diagnosis of VAP.