Phenotypes of Non-Attached Pseudomonas aeruginosa Aggregates Resemble Surface Attached Biofilm

For a chronic infection to be established, bacteria must be able to cope with hostile conditions such as low iron levels, oxidative stress, and clearance by the host defense, as well as antibiotic treatment. It is generally accepted that biofilm formation facilitates tolerance to these adverse conditions. However, microscopic investigations of samples isolated from sites of chronic infections seem to suggest that some bacteria do not need to be attached to surfaces in order to establish chronic infections. In this study we employed scanning electron microscopy, confocal laser scanning microscopy, RT-PCR as well as traditional culturing techniques to study the properties of Pseudomonas aeruginosa aggregates. We found that non-attached aggregates from stationary-phase cultures have comparable growth rates to surface attached biofilms. The growth rate estimations indicated that, independently of age, both aggregates and flow-cell biofilm had the same slow growth rate as a stationary phase shaking cultures. Internal structures of the aggregates matrix components and their capacity to survive otherwise lethal treatments with antibiotics (referred to as tolerance) and resistance to phagocytes were also found to be strikingly similar to flow-cell biofilms. Our data indicate that the tolerance of both biofilms and non-attached aggregates towards antibiotics is reversible by physical disruption. We provide evidence that the antibiotic tolerance is likely to be dependent on both the physiological states of the aggregates and particular matrix components. Bacterial surface-attachment and subsequent biofilm formation are considered hallmarks of the capacity of microbes to cause persistent infections. We have observed non-attached aggregates in the lungs of cystic fibrosis patients; otitis media; soft tissue fillers and non-healing wounds, and we propose that aggregated cells exhibit enhanced survival in the hostile host environment, compared with non-aggregated bacterial populations

The limitations of in vitro experimentation in understanding biofilms and chronic infection

We have become increasingly aware that during infection, pathogenic bacteria often grow in multi- cellular biofilms which are often highly resistant to antibacterial strategies. In order to understand how biofilms form and contribute to infection, in vitro biofilm systems such as microtitre plate as- says and flow cells, have been heavily used by many research groups around the world. Whilst these methods have greatly increased our understanding of the biology of biofilms, it is becoming increasingly apparent that many of our in vitro methods do not accurately represent in vivo conditions. Here we present a systematic review of the most widely used in vitro biofilm systems, and we discuss why they are not always representative of the in vivo biofilms found in chronic infections. We present examples of methods that will help us to bridge the gap between in vitro and in vivo biofilm work, so that our bench-side data can ultimately be used to improve bedside treatment

Prevalence of self-reported middle ear disease, hearing loss and vertigo in two adult population-based cohorts over a 20-year period in Greenland

ABSTRACTTo estimate the frequencies of self-reported middle ear and hearing complaints and vertigo/dizziness in adult Greenlanders. Furthermore, to examine if there has been a development in the frequency of these complaints within a 20-year period. A structured questionnaire concerning middle ear disease and related neuro-otological symptoms was mailed to 400 randomly selected adult Greenlanders between 18 and 60 years of age in 1995. In 2014, the questions were included for the same age group in the general Greenlandic Health Survey. The questionnaires contained a total of six identical questions. In 1995, 281 participants (70%) replied to the questionnaire. In 2014, 1,639 participants (78%) replied. We found that in 1995 the two youngest age groups (18–29- and 30–39-year-olds) had the highest relative number of ear discharge. Approximately one-third of the participants in these two age groups reported to have had ear discharge, while this was only reported by 17% of the 18–29-year-olds and 16% of the 30–39-year-olds in 2014 (95% CI [0.03, 0.3] and [0.1, 0.3], respectively). The oldest age group indicated the lowest relative number of experiences of ear discharge in both 1995 and 2014 (18% and 17%, respectively). In 1995, 30% in the age group 30–39-year-olds reported hearing loss, whereas only 18% reported hearing loss in 2014 (p < 0.05, 95% CI [-0.003,0.2]). There was no significant difference in reported ear discharge since childhood and otitis media in childhood among the age groups between 1995 and 2014. However, in 1995 significantly more females had experienced ear discharge in the age groups 18–29 and 30–39 year-olds compared to 2014. Females in the age group 18–29 year-olds also showed a significant difference in having experienced otitis media in childhood, where 32% answered “yes” in 1995, and 18% answered “yes” in 2014 (p < 0.05). In 2014, females reported more frequent complaints of vertigo compared to males, 16% and 9%, respectively (p < 0.05). In 1995, there was no significant difference in experienced vertigo between males and females. Ear and hearing health problems and vertigo are reported frequently in the Greenlandic population. Overall, a tendency of less complaints in 2014 compared to 1995 except for vertigo. It is important to follow this trend and increase the prophylactic efforts to reduce common health disabilities like early otitis media in childhood and noise created symptoms even more

Childhood health as reflected in adult urban and rural samples from medieval Denmark

This study examines the evidence of three skeletal markers relating to childhood health that leave permanent observable changes in the adult skeleton. Two are well known to paleopathology, namely Harris lines (HL) and linear enamel hypoplasia (LEH). The third skeletal marker is less commonly used; the permanent changes in the temporal bones, induced by chronic or recurrent infectious middle ear disease (IMED) in childhood. A total of 291 adult skeletons from an urban (n = 109) and a rural (n = 182) cemetery, from the Danish medieval period (1050–1536 CE) were included. The markers were examined for their co-occurrence, and differences between the two samples. No statistically significant difference for the three skeletal markers between the two samples was found. A trend was nevertheless apparent, with greater frequencies for all three skeletal markers for the urban population. A statistically significant relationship was found only between IMED and HL. This positive relation was very low (rɸ = 0.307, 0.275) and may be considered non-existent. The lack of co-occurrence is interpreted as if an individual was exposed to conditions that could cause the osteological expression of all three markers this could be a life-threatening health condition, during developing years