Mixed community-acquired lower respiratory tract infections

Biomarkers of Community-Acquired Pneumonia: A Key to Disease Diagnosis and Management

Community-acquired pneumonia (CAP) is a dangerous disease caused by a spectrum of bacterial and viral pathogens. The choice of specific therapy and the need for hospitalization or transfer to the intensive care unit are determined by the causative agent and disease severity. The microbiological analysis of sputum largely depends on the quality of the material obtained. The prediction of severity and the duration of therapy are determined individually, and existing prognostic scales are used generally. This review examines the possibilities of using specific serological biomarkers to detect the bacterial or viral aetiology of CAP and to assess disease severity. Particular emphasis is placed on the use of biomarker signatures and the discovery of biomarker candidates for a single multiplex analysis.

Pneumonia and Pleural Empyema due to a Mixed Lactobacillus spp. Infection as a Possible Early Esophageal Carcinoma Signature

Lactobacilli are human commensals found in the gastrointestinal and genitourinary tract. Although generally conceived as non-pathogenic microorganisms, the existence of several reports implicating them in certain severe pathological entities renders this species as opportunistic pathogens. The case of a 58-year-old woman with mixed Lactobacillus infection is described. The patient was admitted in an outpatient clinic with community acquired pneumonia, and on the third day of hospitalization she presented rapid pneumonia deterioration. Subsequent imaging techniques revealed increased pleural empyema in alignment with the general deterioration of her clinical condition. Pleural fluid culture revealed the presence of Lactobacillus delbrueckii and Lactobacillus gasseri and the infection was successfully treated with clindamycin. Five months after hospital discharge and an overall good condition, the patient developed signs of dysphagia and upon re-admission an inoperable esophageal carcinoma was diagnosed. The patient succumbed to the cancer 11 months later. Herein, we report for the first time a mixed respiratory infection due to lactobacilli, possibly associated with a formerly unveiled esophageal malignancy.

Polymicrobial interactions: impact on pathogenesis and human disease

Microorganisms coexist in a complex milieu of bacteria, fungi, archaea, and viruses on or within the human body, often as multifaceted polymicrobial biofilm communities at mucosal sites and on abiotic surfaces. Only recently have we begun to appreciate the complicated biofilm phenotype during infection; moreover, even less is known about the interactions that occur between microorganisms during polymicrobial growth and their implications in human disease. Therefore, this review focuses on polymicrobial biofilm-mediated infections and examines the contribution of bacterial-bacterial, bacterial-fungal, and bacterial-viral interactions during human infection and potential strategies for protection against such diseases.

Vaccine development in Staphylococcus aureus: taking the biofilm phenotype into consideration

Vaccine development against pathogenic bacteria is an imperative initiative as bacteria are gaining resistance to current antimicrobial therapies and few novel antibiotics are being developed. Candidate antigens for vaccine development can be identified by a multitude of high-throughput technologies that were accelerated by access to complete genomes. While considerable success has been achieved in vaccine development against bacterial pathogens, many species with multiple virulence factors and modes of infection have provided reasonable challenges in identifying protective antigens. In particular, vaccine candidates should be evaluated in the context of the complex disease properties, whether planktonic (e.g. sepsis and pneumonia) and/or biofilm associated (e.g. indwelling medical device infections). Because of the phenotypic differences between these modes of growth, those vaccine candidates chosen only for their efficacy in one disease state may fail against other infections. This review will summarize the history and types of bacterial vaccines and adjuvants as well as present an overview of modern antigen discovery and complications brought about by polymicrobial infections. Finally, we will also use one of the better studied microbial species that uses differential, multifactorial protein profiles to mediate an array of diseases, Staphylococcus aureus, to outline some of the more recently identified problematic issues in vaccine development in this biofilm-forming species.

Modelling the bacterial communities associated with cystic fibrosis lung infections

In many human diseases that cystic fibrosis (CF) patients suffer from, for example, lung infections, bacteria have been considered to grow as biofilms. The ability of key CF pathogens such as Pseudomonas aeruginosa to resist antibiotic therapies may be due to the poor drug penetration of these biofilms. The overall aim of this study was to develop biofilm models in vitro that resembled the bacterial species composition of CF sputa. Here, this was a step towards a longer term goal of forming multiple bacterial biofilm models in vitro that would serve, in turn, as better assays of antibiotic susceptibilities than conventionally grown cells. Biofilm models were constructed from 31 CF sputum samples, using a modified microtitre plate assay. Three forms of assessment of these biofilms were made, namely, the mass, microscopic analysis and species composition. Species composition in sputa and biofilms, characterised by terminal restriction fragment length polymorphism (T-RFLP) analysis of ribosomal gene polymerase chain reaction (PCR) products amplified from directly extracted nucleic acids, indicated that the bacterial community in sputa was well reproduced in the biofilm models. Typically, fresh sputa contained 4.6 +/- 2.3 bacterial species, with the species number decreasing to 4.0 +/- 1.6 over 5 days-this was not statistically significant (p = 0.29). This study outlines a novel methodology by which to generate and study bacterial biofilms communities. It is also hoped that the versatility of this in vitro approach, combined with its simplicity and high reproducibility, will make it an effective system to study CF sputum biofilm development and, in the longer term, serve as a means of assessing antibiotic susceptibilities.

Overcoming penicillin failures in the treatment of Group A streptococcal pharyngo-tonsillitis

The causes of penicillin failure in eradicating Group A beta-hemolytic streptococcal pharyngo-tonsillitis (GABHS PT) are described. These include the presence of beta-lactamase producing bacteria that "protect" Group A beta-hemolytic streptococci (GABHS) from penicillins; the absence of bacteria that interfere with the growth of GABHS; co-aggregation between GABHS and Moraxella catarrhalis; and the poor penetration of penicillin into the tonsillar tissues and the tonsillo-pharyngeal cells. The use of antimicrobials that can overcome and modulate these phenomena and achieve better cure of the infection is described.