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Between 1953 and 1962, 21 patients presented with bronchial strictures. Bronchial reconstruction was carried out on 15 of these while a dermal graft was employed in another six patients. The follow-up period, therefore, is between 10 and 20 years. Bronchial structures lend themselves to satisfactory reconstruction. This review, however, showed that late contraction of a dermal graft may occur even two years after operation. [ABSTRACT FROM PUBLISHER]

The changes in pulmonary compliance have been studied under conditions of total body hypothermia. Five groups of sheep were used; two groups were controls—one for the effects of anaesthesia and the other for normothermic biventricular bypass. The third group was cooled using a femoro-femoral arterio-venous shunt to 20°-23° C. The fourth group was cooled to 15° C. and rewarmed using the Drew technique. The excised lungs of the remaining sheep were studied at 37° and 15° C. (fifth group). The controls showed little change in compliance. The cooled animals showed a decrease in compliance. In the group subjected to hypothermia by the Drew technique, the rewarming phase initially brought a return towards normal compliance. As the temperature rose to 24°-30° C. the improvement in compliance ceased and thereafter compliance decreased for two hours after rewarming. Histologically the lungs were normal. There was no compliance change caused by cooling the excised lungs. [ABSTRACT FROM PUBLISHER]

Abstract Background Internalin A (InlA) is a critical virulence factor which mediates the initiation of Listeria monocytogenes infection by the oral route in permissive hosts. The interaction of InlA with the host cell ligand E-cadherin efficiently stimulates L. monocytogenes entry into human enterocytes, but has only a limited interaction with murine cells. Results We have created a surface display library of randomly mutated InlA in a non-invasive heterologous host Lactococcus lactis in order to create and screen novel variants of this invasion factor. After sequential passage through a murine cell line (CT-26), multiple clones with enhanced invasion characteristics were identified. Competitive index experiments were conducted in mice using selected mutations introduced into L. monocytogenes EGD-e background. A novel single amino acid change was identified which enhanced virulence by the oral route in the murine model and will form the basis of further engineering approaches. As a control a previously described EGD-InlAm murinized strain was also re-created as part of this study with minor modifications and designated EGD-e InlAm*. The strain was created using a procedure that minimizes the likelihood of secondary mutations and incorporates Listeria-optimized codons encoding the altered amino acids. L. monocytogenes EGD-e InlAm* yielded consistently higher level murine infections by the oral route when compared to EGD-e, but did not display the two-fold increased invasion into a human cell line that was previously described for the EGD-InlAm strain. Conclusions We have used both site-directed mutagenesis and directed evolution to create variants of InlA which may inform future structure-function analyses of this protein. During the course of the study we engineered a murinized strain of L. monocytogenes EGD-e which shows reproducibly higher infectivity in the intragastric murine infection model than the wild type, but does not display enhanced entry into human cells as previously observed. This murinized L. monocytogenes strain will provide a useful tool for the analysis of the gastrointestinal phase of listeriosis.

Abstract Background The foodborne, gram-positive pathogen, Listeria monocytogenes, is capable of causing lethal infections in compromised individuals. In the post genomic era of L. monocytogenes research, techniques are required to identify and validate genes involved in the pathogenicity and environmental biology of the organism. The aim here was to develop a widely applicable method to tag L. monocytogenes strains, with a particular emphasis on the development of multiple strain competitive index assays. Results We have constructed a new site-specific integrative vector, pIMC, based on pPL2, for the selection of L. monocytogenes from complex samples. The pIMC vector was further modified through the incorporation of IPTG inducible markers (antibiotic and phenotypic) to produce a suite of four vectors which allowed the discrimination of multiple strains from a single sample. We were able to perform murine infection studies with up to four EGDe isolates within a single mouse and showed that the tags did not impact upon growth rate or virulence. The system also allowed the identification of subtle differences in virulence between strains of L. monocytogenes commonly used in laboratory studies. Conclusion This study has developed a competitive index assay that can be broadly applied to all L. monocytogenes strains. Improved statistical robustness of the data was observed, resulting in fewer mice being required for virulence assays. The competitive index assays provide a powerful method to analyse the virulence or fitness of L. monocytogenes in complex biological samples.

Even in the setting of optimal resuscitation in high-income countries severe sepsis and septic shock have a mortality of 20-40%, with antibiotic resistance dramatically increasing this mortality risk. To develop a reference dataset enabling the identification of common bacterial targets for therapeutic intervention, we applied a standardized genomic, transcriptomic, proteomic and metabolomic technological framework to multiple clinical isolates of four sepsis-causing pathogens: Escherichia coli, Klebsiella pneumoniae species complex, Staphylococcus aureus and Streptococcus pyogenes. Exposure to human serum generated a sepsis molecular signature containing global increases in fatty acid and lipid biosynthesis and metabolism, consistent with cell envelope remodelling and nutrient adaptation for osmoprotection. In addition, acquisition of cholesterol was identified across the bacterial species. This detailed reference dataset has been established as an open resource to support discovery and translational research., (© 2023. The Author(s).)

Mutation acquisition is a major mechanism of bacterial antibiotic resistance that remains insufficiently characterised. Here we present RM-seq, a new amplicon-based deep sequencing workflow based on a molecular barcoding technique adapted from Low Error Amplicon sequencing (LEA-seq). RM-seq allows detection and functional assessment of mutational resistance at high throughput from mixed bacterial populations. The sensitive detection of very low-frequency resistant sub-populations permits characterisation of antibiotic-linked mutational repertoires in vitro and detection of rare resistant populations during infections. Accurate quantification of resistance mutations enables phenotypic screening of mutations conferring pleiotropic phenotypes such as in vivo persistence, collateral sensitivity or cross-resistance. RM-seq will facilitate comprehensive detection, characterisation and surveillance of resistant bacterial populations ( https://github.com/rguerillot/RM-seq ).

Mutations in the beta-subunit of bacterial RNA polymerase (RpoB) cause resistance to rifampin (Rif r ), a critical antibiotic for treatment of multidrug-resistant Staphylococcus aureus . In vitro studies have shown that RpoB mutations confer decreased susceptibility to other antibiotics, but the clinical relevance is unknown. Here, by analyzing 7,099 S. aureus genomes, we demonstrate that the most prevalent RpoB mutations promote clinically relevant phenotypic plasticity resulting in the emergence of stable S. aureus lineages, associated with increased risk of therapeutic failure through generation of small-colony variants (SCVs) and coresistance to last-line antimicrobial agents. We found eight RpoB mutations that accounted for 93% (469/505) of the total number of Rif r mutations. The most frequently selected amino acid substitutions affecting residue 481 (H481N/Y) were associated with worldwide expansions of Rif r clones spanning decades. Recreating the H481N/Y mutations confirmed no impact on S. aureus growth, but the H481N mutation promoted the emergence of a subpopulation of stable Rif r SCVs with reduced susceptibility to vancomycin and daptomycin. Recreating the other frequent RpoB mutations showed similar impacts on resistance to these last-line agents. We found that 86% of all Rif r isolates in our global sample carried the mutations promoting cross-resistance to vancomycin and 52% to both vancomycin and daptomycin. As four of the most frequent RpoB mutations confer only low-level Rif r , equal to or below some international breakpoints, we recommend decreasing these breakpoints and reconsidering the appropriate use of rifampin to reduce the fixation and spread of these clinically deleterious mutations. IMPORTANCE Increasing antibiotic resistance in the major human pathogen Staphylococcus aureus is threatening the ability to treat patients with these infections. Recent laboratory studies suggest that mutations in the gene commonly associated with rifampin resistance may also impact susceptibility to other last-line antibiotics in S. aureus ; however, the overall frequency and clinical impact of these mutations are unknown. By mining a global collection of clinical S. aureus genomes and by mutagenesis experiments, this work reveals that common rifampin-induced rpoB mutations promote phenotypic plasticity that has led to the global emergence of stable, multidrug-resistant S. aureus lineages that are associated with increased risk of therapeutic failure through coresistance to other last-line antimicrobials. We recommend decreasing susceptibility breakpoints for rifampin to allow phenotypic detection of critical rpoB mutations conferring low resistance to rifampin and reconsidering the appropriate use of rifampin to reduce the fixation and spread of these deleterious mutations globally.

Objectives: Vancomycin-intermediate Staphylococcus aureus (VISA) is associated with genetic changes that may also impact upon pathogenicity. In the current study, we compared the virulence of clinical VISA strains with their isogenic vancomycin-susceptible progenitors (VSSA)., Methods: Production of the critical virulence protein, α toxin, was assessed using Western blot analysis and was correlated to agr activity using a bioluminescent agr-reporter. Cytotoxicity and intracellular persistence were compared ex vivo for VSSA and VISA within non-professional phagocytes (NPP). Virulence and host immune responses were further explored in vivo using a murine model of bacteraemia., Results: VISA isolates produced up to 20-fold less α toxin compared with VSSA, and this was corroborated by either loss of agr activity due to agr mutation, or altered agr activity in the absence of mutation. VISA were less cytotoxic towards NPP and were associated with enhanced intracellular persistence, suggesting that NPP may act as a reservoir for VISA. Infection with VSSA strains produced higher mortality in a murine bacteraemia model (≥90% 7-day mortality) compared with infection with VISA isolates (20% to 50%, p <0.001). Mice infected with VISA produced a dampened immune response (4.6-fold reduction in interleukin-6, p <0.001) and persistent organ bacterial growth was observed for VISA strains out to 7 days., Conclusions: These findings highlight the remarkable adaptability of S. aureus, whereby, in addition to having reduced antibiotic susceptibility, VISA alter the expression of pathogenic factors to circumvent the host immune response to favour persistent infection over acute virulence., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Staphylococcus aureus, sequence type (ST) 398, is an emerging pathogen and the leading cause of livestock-associated methicillin-resistant S. aureus infections in Europe and North America. This strain is characterized by high promiscuity in terms of host-species and also lacks several traditional S. aureus virulence factors. This does not, however, explain the apparent ease with which it crosses species-barriers. Recently, TIR-domain containing proteins (Tcps) which inhibit the innate immune response were identified in some Gram-negative bacteria. Here we report the presence of two proteins, S. aureus TIR-like Protein 1 (SaTlp1) and S. aureus TIR-like Protein 2 (SaTlp2), expressed by ST398 which contain domain of unknown function 1863 (DUF1863), similar to the Toll/IL-1 receptor (TIR) domain. In contrast to the Tcps in Gram-negative bacteria, our data suggest that SaTlp1 and SaTlp2 increase activation of the transcription factor NF-κB as well as downstream pro-inflammatory cytokines and immune effectors. To assess the role of both proteins as potential virulence factors knock-out mutants were created. These showed a slightly enhanced survival rate in a murine infectious model compared to the wild-type strain at one dose. Our data suggest that both proteins may act as factors contributing to the enhanced ability of ST398 to cross species-barriers.

Oncocytomas are rare tumours of the adrenal glands whose malignant potential is difficult to assess with certainty. We report a case of an adrenal oncocytoma and present a review of the literature particularly with regards to the radiological and histopathological features and their impact on the management.Adrenal oncocytomas are usually identified incidentally on imaging and can achieve large sizes. They should be considered in the differential diagnosis of any large upper abdominal lesion including those apparently arising from the liver as in this case report. MRI scan appears to be the ideal imaging modality to characterise such lesions. There seems to be little benefit in biopsying these masses and surgery remains the most optimal management. It remains difficult to predict metastatic behaviour based on histological findings and so long term surveillance is advisable.

Contaminated surfaces of food processing equipment are believed to be a significant source of Listeria monocytogenes to foods. However, very little is known about the survival of Listeria in processing environments. In a mixed bacterial biofilm of L. monocytogenes and Flavobacterium spp., the number of L. monocytogenes cells attaching to stainless steel increased significantly compared to when L. monocytogenes was in a pure culture. The L. monocytogenes cells in the mixed biofilms were also recoverable for significantly longer exposure periods. On colonized coupons held at 15 degrees C and 75% humidity, decimal reduction times were 1.2 and 18.7 days for L. monocytogenes in pure and mixed biofilms, respectively. With increasing exposure time, the proportion of cells that were sublethally injured (defined as an inability to grow on selective agar) increased from 8.1% of the recoverable cell population at day 0 to 91.4% after 40 days' exposure. At 4 and -20 degrees C, decimal reduction times for L. monocytogenes in pure culture were 2.8 and 1.4 days, respectively, and in mixed culture, 10.5 and 14.4 days, respectively. The enhanced colonization and survival of L. monocytogenes on "unclean" surfaces increase the persistence of this pathogen in food processing environments, while the increase in the percentage of sublethally injured cells in the population with time may decrease the ability of enrichment regimes to detect it.

An expired gas collection and disposal system based on an independent suction pump is described. The halothane concentration in the atmosphere was measured, with and without the system. The increase of halothane concentration was limited to 1 p.p.m. above the theatre basal value with the system in use, and 5 p.p.m. when no venting was used.