Introduction Infection is a major cause of morbidity and mortality in patients with cystic fibrosis (CF). Research on CF infection has highlighted differences from other respiratory infections—both ...in the range and the nature of the organisms—especially in chronic infection. This is a rapidly advancing field of microbiology and is bringing insights into the complexity and adaptations of bacteria causing chronic infection in the respiratory tract. Areas of agreement and controversy The epidemiology of some infections in CF has changed, with reduction in spread of Burkholderia cenocepacia following patient segregation. Conversely, epidemic strains of Pseudomonas aeruginosa have emerged, which spread between patients; previously, most P. aeruginosa strains were patient-specific. Studies on hypermutators, quorum sensing, biofilm growth and the development of molecular identification have shed light on pathogenicity, microbial adaptation to the host and complexity of infection in CF. Non-tuberculous mycobacteria are emerging pathogens in CF; however, there is much to learn about pathogenicity and treatment of these infections. Species of aerobic and anaerobic bacteria, more commonly encountered in the upper tract, are found in significant numbers in CF sputum. The significance of this is however under debate. Finally, although the clinical relevance of conventional antibiotic susceptibility testing for chronic CF pathogens has been questioned, there are no clear alternatives. Emerging areas for developing research Much has been learnt about pathogenicity, evolution of CF pathogens and development of antibiotic resistance. The need is to focus on clinical relevance of these observations to improve diagnosis, prevention and treatment of CF infection.
The BSAC guidelines on treatment of infectious endocarditis (IE) were last published in 2004. The guidelines presented here have been updated and extended to reflect developments in diagnostics, new ...trial data and the availability of new antibiotics. The aim of these guidelines, which cover both native valve and prosthetic valve endocarditis, is to standardize the initial investigation and treatment of IE. An extensive review of the literature using a number of different search criteria has been carried out and cited publications used to support any changes we have made to the existing guidelines. Publications referring to in vitro or animal models have only been cited if appropriate clinical data are not available. Randomized, controlled trials suitable for the development of evidenced-based guidelines in this area are still lacking and therefore a consensus approach has again been adopted for most recommendations; however, we have attempted to grade the evidence, where possible. The guidelines have also been extended by the inclusion of sections on clinical diagnosis, echocardiography and surgery.
Objectives: To investigate the variability in antimicrobial susceptibility of Pseudomonas aeruginosa from sputa of patients with cystic fibrosis, to compare testing individual colonies of the same ...morphotype either separately or combined and to study the reproducibility of testing antimicrobial susceptibility within and between laboratories. Methods: One hundred and one sputa were cultured. Four colonies of each P. aeruginosa morphotype were suspended. Susceptibility to 12 agents by disc diffusion was tested individually or by pooling the four suspensions. A sputum sample containing four morphotypes of one genotype of P. aeruginosa was used to study reproducibility. Susceptibility was tested in duplicate by eight biomedical scientists in one laboratory and by routine procedures in seven different laboratories. Results: There was a mean of four morphotypes of P. aeruginosa per sputum and three antibiograms per morphotype. In some cases, all four colonies of a single morphotype had different antibiograms. The susceptibility profiles of single isolates of P. aeruginosa correlated poorly with pooled cultures, with the pooled tests missing resistance. Results from one sample tested in duplicate by eight biomedical scientists in one laboratory and in seven other laboratories did not correlate well. The wide range of zone sizes in disc diffusion tests illustrated the variation in susceptibility of 48 colonies from one sputum sample. Conclusions: The role of conventional antimicrobial susceptibility testing is questionable once P. aeruginosa chronically infects the cystic fibrosis lung. A range of susceptibility patterns is seen, even within a morphotype. Routine test results are not reproducible and underestimate resistance.
These guidelines have been produced following a literature review of the requirement for prophylaxis to prevent bacterial endocarditis following dental and surgical interventions. Recommendations are ...made based on the quality of available evidence and the consequent risk of morbidity and mortality for ‘at risk’ patients.
Bronchiectasis is a pathologic description of lung damage characterized by inflamed and dilated thick-walled bronchi. These findings may result from a number of possible causes and these may ...influence treatment and prognosis. The aim of this study was to determine causative factors in 150 adults with bronchiectasis (56 male, 94 female) identified using high-resolution computerized tomography. Relevant factors were identified in the clinical history; cystic fibrosis gene mutation analysis was performed; humoral immune defects were determined by measuring immunoglobulins, IgG subclasses and functional response to Pneumovax II vaccine; assessment was made of neutrophil function (respiratory burst, adhesion molecule expression, and chemotaxis); ciliary function was observed and those likely to have allergic bronchopulmonary aspergillosis (ABPA) were identified. Causes identified were: immune defects (12 cases), cystic fibrosis (4), Young's syndrome (5), ciliary dysfunction (3), aspiration (6), panbronchiolitis (1), congenital defect (1), ABPA (11), rheumatoid arthritis (4), and early childhood pneumonia, pertussis, or measles (44). Intensive investigation of this population of patients with bronchiectasis led to identification of one or more causative factor in 47% of cases. In 22 patients (15%), the cause identified had implications for prognosis and treatment.
The aim of the current study was to investigate the prevalence and clinical associations of nontuberculous mycobacteria (NTM) in a well-characterised cohort of patients with adult-onset ...bronchiectasis. The sputum of all patients attending a tertiary referral bronchiectasis clinic between April 2002 and August 2003 was examined for mycobacteria as part of an extensive diagnostic work-up. NTM-positive patients subsequently had further sputa examined. A modified bronchiectasis scoring system was applied to all high-resolution computed tomography (HRCT) scans from NTM-positive patients, and a matched cohort without NTM. Out of 98 patients attending the clinic, 10 had NTM in their sputum on first culture; of those, eight provided multiple positive cultures. Three patients were treated for NTM infection. A higher proportion of NTM-positive than -negative patients were subsequently diagnosed with cystic fibrosis (two out of nine versus two out of 75). On HRCT scoring, more patients in the NTM-positive group had peripheral mucus plugging than in the NTM-negative group. In the current prospective study of a large cohort of patients with bronchiectasis, 10% cultured positive for nontuberculous mycobacteria in a random clinic sputum sample. Few clinical parameters were helpful in discriminating between groups, except for a higher prevalence of previously undiagnosed cystic fibrosis and of peripheral mucus plugging on high-resolution computed tomography in the nontuberculous mycobacteria group.
Objectives To investigate variability in colony morphology and antibiotic susceptibility in populations of Pseudomonas aeruginosa from sputa of patients with bronchiectasis without cystic fibrosis ...(CF) compared with P. aeruginosa isolated from patients with CF, and from other infections as controls. Methods P. aeruginosa was cultured from 31 patients with non-CF bronchiectasis, 24 with CF, 7 ventilated patients and 9 skin swabs. Four colonies of each morphotype of P. aeruginosa were tested for susceptibility to 12 antibiotics by disc diffusion. The variability in susceptibility between the isolates in each patient’s population of P. aeruginosa was investigated. Results The classic morphotype of P. aeruginosa was cultured from control samples with an average variation in zone size of 2 mm (range 0–4 mm) for the four colonies tested. Non-CF bronchiectasis sputa contained 1–3 colonial morphotypes of P. aeruginosa; the average difference between the largest and smallest zone sizes found in all examples of the morphotypes present in each sample varied from 3 mm (1–9 mm) for colistin to 8 mm (0–24 mm) for piperacillin/tazobactam. CF sputa contained 2–6 morphotypes of P. aeruginosa with a wider variation of susceptibility. There was variation between bacteria of the same morphotype from non-CF bronchiectasis and CF sputa. Conclusions Phenotypic variation in colonial form and antibiotic susceptibility is not unique to chronic infection in CF but is also found in non-CF bronchiectasis. This questions the use of current susceptibility testing methods for the complex populations of bacteria found in chronic lung infection.
Mycobacterium abscessus
M. abscessus
(
sensu lato
) or
M. abscessus
complex comprises three closely related species:
M. abscessus
(
sensu stricto
), hereafter referred to as
M. abscessus
,
M. ...bolletii
and
M. massiliense
. We describe here an accurate and robust method for distinguishing
M. chelonae
from
M. abscessus
,
M. bolletii
and
M. massiliense
, using polymerase chain reaction (PCR) and the sequencing of house-keeping gene targets (
hsp65
and
rpoB
). Sequencing of the
sodA
gene is of little additional value in discriminating between species, but
M. massiliense
can be rapidly identified by amplification of the truncated
erm
(41) gene without the need for amplicon sequencing. We have applied the method to 81 isolates from 40 patients from two hospitals, the majority of whom were cystic fibrosis (CF) patients. Of these patients, 21 had previously been identified as
M. chelonae
and 59 as
M. abscessus
complex using commercial line probe assays. We identified these as 46
M. abscessus
isolates, 20
M. massiliense
isolates, five
M. bolletii
isolates and nine
M. chelonae
isolates and confirmed the one
M. fortuitum
isolate. This is the first study that has identified the individual members of the
M. abscessus
complex in a UK cohort of mainly CF patients.
The BSAC Guidelines on Endocarditis were last published in 1998. The Guidelines presented here have been updated and extended to reflect changes in both the antibiotic resistance characteristics of ...causative organisms and the availability of new antibiotics. Randomized, controlled trials suitable for the development of evidenced-based guidelines in this area are still lacking, and therefore a consensus approach has again been adopted. The Guidelines cover diagnosis and laboratory testing, suitable antibiotic regimens and causative organisms. Special emphasis is placed on common causes of endocarditis, such as streptococci and staphylococci, however, other bacterial causes (such as enterococci, HACEK organisms, Coxiella and Bartonella) and fungi are considered. The special circumstances of prosthetic endocarditis are discussed.
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