Lay concepts and strategies for handling symptoms of disease. A sample of adult men and women experiencing back pain symptoms

A population sample of 60 men and women who had experienced back pains were interviewed in-depth with semi-structured techniques. Though two thirds of the sample had symptoms of severe or moderately severe character, less than half had any current contact with doctors. Interviews were taped and analysed qualitatively. Results show that almost all respondents continually develop ideas and concepts about their disease built upon the experiences and experiments of everyday activities over a long period, rather than upon medical information. Most respondents subscribed to a multifactorial view of the disease and some had quite sophisticated models of processes leading to symptom emergence. However, models almost invariably were of the "black-box type", specifying influences and outcomes but being blank on what was going on inside the body. Most respondents preferred not to see themselves as ill. They were nevertheless concerned with disease concepts and causes because correct disease modelling would give them information on the likely future development of symptoms, i.e. prognostic information, which in turn reduced anxiety and strengthened their mental and practical control of illness. Control of illness was practiced in several ways. We identified four main types of strategy towards illness: Ignoring/neclecting symptoms of disease. Routine treatment during symptom periods (professional/self-care). Preventive behaviour. Permanent change or modification of life situation. Roughly half of respondents were strategy-two users. The current concept and policy of individual health responsibility is discussed in light of the results.

The Global Regulator CcpA of Listeria monocytogenes Confers Sensitivity to Antimicrobial Fatty Acids

Free fatty acids (FFAs) are known to exhibit antimicrobial and anti-virulent properties against bacterial pathogens. Specific FFAs, such as lauric acid (LA; C12:0), exert both effects against the foodborne pathogen Listeria monocytogenes: at low levels, LA acts to inhibit the activity of the virulence regulator PrfA, whereas at higher levels, LA inhibits bacterial growth. Deletion of prfA is known to promote tolerance toward antimicrobial FFAs, suggesting that the response of L. monocytogenes to anti-virulent and antimicrobial FFAs could be linked. In this study, we explored the response of L. monocytogenes toward antimicrobial FFAs holding an anti-virulence activity by isolating strains that can grow at high concentrations of LA. We found that LA-tolerant isolates carry mutations in the gene encoding the global regulator CcpA. Importantly, we discovered that mutation or deletion of ccpA protect L. monocytogenes against the antimicrobial activity of FFAs, whereas the ccpA mutants remain sensitive toward FFA’s PrfA inhibitory effect. A regulatory link involving CcpA, connecting the response toward the antimicrobial and anti-virulence activities of FFAs, is therefore unlikely. To further study how deletion of ccpA promotes FFA tolerance, we performed a transcriptomic analysis of the response to LA. Our data indicated that the FFA-tolerant phenotype of the ∆ccpA strain is not induced upon LA exposure but appears to be an inherent phenotypic trait of the ccpA deletion mutation. Interestingly, we found that the bacterial surface of L. monocytogenes becomes more hydrophilic upon deletion of ccpA, and we demonstrate that CcpA plays a role in the response of L. monocytogenes to other stress conditions, including low pH and antibiotics. Altogether, our study revealed that regulatory activities of CcpA lead to an increased hydrophobicity of the bacterial surface, which may confer sensitivity of L. monocytogenes against the antimicrobial activity of FFAs. Notably, CcpA is not involved in responding to the PrfA inhibitory effect of FFAs, showing that FFA-tolerant strains can still be targeted by the anti-virulent activity of FFAs.

dos Santos P, Houborg SD, Lillebæk EMS, Kemp M, Kallipolitis BH. Long-chain unsaturated free fatty acids reduce the host cell invasion of Listeria monocytogenes outbreak strains

The Gram-positive bacterium Listeria monocytogenes is a highly adaptable pathogen capable of causing severe foodborne infections, particularly in vulnerable populations. During infection, L. monocytogenes uses a variety of virulence factors to invade and multiply within host cells. The transcriptional regulator PrfA controls the expression of these virulence factors and is essential for the intracellular lifestyle of L. monocytogenes. Long-chain unsaturated free fatty acids (FFAs) have long been recognized for their antimicrobial activity and were recently shown to inhibit PrfA-dependent virulence gene expression in L. monocytogenes. To date, the antimicrobial and anti-virulent activities of FFAs have been primarily studied in laboratory strains. However, to fully evaluate their potential as anti-infective agents, it is essential to assess the effects of long-chain FFAs on clinically relevant isolates, including outbreak strains associated with high-fat food products. Here, we demonstrate that five different clinically relevant L. monocytogenes isolates are sensitive to the antimicrobial activity of long-chain unsaturated FFAs. Furthermore, at subinhibitory concentrations, these FFAs inhibit PrfA-regulated expression of virulence factors across all tested strains and reduce their invasive potential in non-phagocytic cells. These findings underscore the potential of long-chain unsaturated FFAs in developing new preventive strategies against L. monocytogenes strains associated with severe foodborne infections.