[Molecular diagnostic methods of respiratory infections. Has the scheme diagnosis changed?]. / Métodos moleculares de diagnóstico de infecciones respiratorias. ¿Ha cambiado el esquema diagnóstico?

Lower respiratory tract infections remain one of the most common causes of mortality worldwide, which is why early diagnosis is crucial. Traditionally the microbiological diagnosis of these infections has been based on conventional methods including culture on artificial media for isolation of bacteria and fungi and cell cultures for virus and antibody or antigen detection using antigen-antibody reactions. The main drawback of the above mentioned methods is the time needed for an etiological diagnosis of the infection. The techniques based on molecular biology have drawn much attention in recent decades as tools for rapid diagnosis of infections. Some techniques are very expensive, especially those that can detect various microorganisms in the same reaction, therefore the question that arises is whether the cost of such testing is justified by the information obtained and by the clinical impact that its implementation will determine. In this article we make a review of the various techniques of molecular biology applied to the diagnosis of pneumonia and focus primarily on analysing the impact they may have on the management of patients with acute respiratory tract infections.

Structural and functional evaluation of the palindromic alanine-rich antimicrobial peptide Pa-MAP2.

Recently, several peptides have been studied regarding the defence process against pathogenic microorganisms, which are able to act against different targets, with the purpose of developing novel bioactive compounds. The present work focuses on the structural and functional evaluation of the palindromic antimicrobial peptide Pa-MAP2, designed based on the peptide Pa-MAP from Pleuronectes americanus. For a better structural understanding, molecular modelling analyses were carried out, together with molecular dynamics and circular dichroism, in different media. Antibacterial activity against Gram-negative and positive bacteria was evaluated, as well as cytotoxicity against human erythrocytes, RAW 264.7, Vero and L6 cells. In silico docking experiments, lipid vesicle studies, and atomic force microscopy (AFM) imaging were carried out to explore the activity of the peptide. In vivo studies on infected mice were also done. The palindromic primary sequence favoured an α-helix structure that was pH dependent, only present on alkaline environment, with dynamic N- and C-terminals that are stabilized in anionic media. Pa-MAP2 only showed activity against Gram-negative bacteria, with a MIC of 3.2 µM, and without any cytotoxic effect. In silico, lipid vesicles and AFM studies confirm the preference for anionic lipids (POPG, POPS, DPPE, DPPG and LPS), with the positively charged lysine residues being essential for the initial electrostatic interaction. In vivo studies showed that Pa-MAP2 increases to 100% the survival rate of mice infected with Escherichia coli. Data here reported indicated that palindromic Pa-MAP2 could be an alternative candidate for use in therapeutics against Gram-negative bacterial infections.

[Outbreaks caused by diarrheagenic Escherichia coli]. / Brotes epidémicos causados por Escherichia coli diarreagénicas.

Escherichia coli are ubiquitous bacteria from a wide variety of ecosystems including the gastrointestinal tract of humans and warm-blooded animals. E. coli can play a role as an opportunistic bacteria causing a variety of infectious diseases including, among many others, sepsis, urinary tract infections, meningitis, and wound infections. Moreover, these bacteria can also act as primary pathogens in the intestinal tract. There are several pathotypes of E. coli that cause enteritis, and both sporadic cases and outbreaks have been reported. In this article, we review the pathogenicity and epidemiology of enteritis caused by these E. coli pathotypes, and provide some examples of outbreaks described in the scientific literature and the measures required to prevent them.