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Recent technical developments in microbiology have led to new discoveries on the within-host dynamics of bacterial infections in laboratory animals. In particular, they have highlighted the importance of stochastic bottlenecks at the onset of invasive disease. A number of approaches exist for bottleneck-size estimation with respect to within-host bacterial infections; however, some are more appropriate than others under certain circumstances. A Bayesian comparison of several approaches is made in terms of the availability of isogenic multitype bacteria (e.g., WITS), knowledge of post-bottleneck dynamics, and the suitability of dilution with monotype bacteria. A sampling approach to bottleneck-size estimation is also introduced. The results are summarised by a guiding flowchart, which we hope will promote the use of quantitative models in microbiology to refine the analysis of animal experiment data. [ABSTRACT FROM AUTHOR]

Objectives: We determined the interactions between efficacy of antibiotic treatment, pathogen growth rates and between-organ spread during systemic Salmonella infections.Methods: We infected mice with isogenic molecularly tagged subpopulations of either a fast-growing WT or a slow-growing ΔaroC Salmonella strain. We monitored viable bacterial numbers and fluctuations in the proportions of each bacterial subpopulation in spleen, liver, blood and mesenteric lymph nodes (MLNs) before, during and after the cessation of treatment with ampicillin and ciprofloxacin.Results: Both antimicrobials induced a reduction in viable bacterial numbers in the spleen, liver and blood. This reduction was biphasic in infections with fast-growing bacteria, with a rapid initial reduction followed by a phase of lower effect. Conversely, a slow and gradual reduction of the bacterial load was seen in infections with the slow-growing strain, indicating a positive correlation between bacterial net growth rates and the efficacy of ampicillin and ciprofloxacin. The viable numbers of either bacterial strain remained constant in MLNs throughout the treatment with a relapse of the infection with WT bacteria occurring after cessation of the treatment. The frequency of each tagged bacterial subpopulation was similar in the spleen and liver, but different from that of the MLNs before, during and after treatment.Conclusions: In Salmonella infections, bacterial growth rates correlate with treatment efficacy. MLNs are a site with a bacterial population structure different to those of the spleen and liver and where the total viable bacterial load remains largely unaffected by antimicrobials, but can resume growth after cessation of treatment. [ABSTRACT FROM AUTHOR]

AimsTo investigate whether pseudophakic and phakic rhegmatogenous retinal detachment (RRD) patterns differ.MethodsRetrospective review of electronic database of patients, aged 50 years or over, presenting to our vitreoretinal service. Data included baseline characteristics, digital drawings, and outcomes. Retinal drawings were analysed in a masked fashion for site, size, and number of retinal breaks. Comparisons were made between the following groups and subgroups: pseudophakic eyes, phakic eyes, phakic eyes with cataract, and phakic eyes without cataract.ResultsOf 500 eyes included, 146 were pseudophakic; 177 of the phakic eyes had cataract. The following were significant by univariate analysis: pseudophakic patients were older than phakic patients in general, but the same age as patients with cataract; in the pseudophakic group, there were lower proportions of females and of patients presenting with vitreous haemorrhage or with large or superotemporal breaks; higher proportions of pseudophakic eyes had small breaks and inferonasal breaks. Some differences remained significant when comparing pseudophakia eyes with cataract. Multivariate analysis comparing pseudophakia with phakia confirmed a lower chance in pseudophakia of large breaks, vitreous haemorrhage and superotemporal breaks, but higher chance of detached inferior breaks. Some variables were age dependent.ConclusionDifferences were found between pseudophakic and phakic RRD patterns. These suggest special pathogenetic mechanisms in pseudophakic retinal detachment, which could help explain increased incidences of RRD after cataract surgery. [ABSTRACT FROM AUTHOR]