The use of a two-gene sequencing approach to accurately distinguish between the species within the Mycobacterium abscessus complex and Mycobacterium chelonae.

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.

Variable antibiotic susceptibility in populations of Pseudomonas aeruginosa infecting patients with bronchiectasis.

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.

Nontuberculous mycobacteria in bronchiectasis: Prevalence and patient characteristics.

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.

Guidelines for the prevention of endocarditis: report of the Working Party of the British Society for Antimicrobial Chemotherapy.

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.

Phenotypic variability of Pseudomonas aeruginosa in sputa from patients with acute infective exacerbation of cystic fibrosis and its impact on the validity of antimicrobial susceptibility testing.

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.

Gentamicin induced ototoxicity during treatment of enterococcal endocarditis: resolution with substitution by netilmicin.

Enterococcal endocarditis can be very difficult to eradicate, requiring prolonged treatment with a combination of a penicillin and an aminoglycoside. In this patient with a pacemaker associated enterococcal endocarditis, ototoxicity occurred due to total gentamicin dose despite plasma concentrations consistently within the treatment range. Substitution with netilmicin, without a break in aminoglycoside treatment, resulted in a rapid improvement in hearing and allowed the required course of aminoglycoside to be completed. The risk factors for ototoxicity with gentamicin are reviewed, in particular the dangers of increasing age and of multiple and prolonged courses. Close treatment monitoring does not totally avoid this risk, especially when prolonged aminoglycoside treatment is required. This case emphasises the need for prompt investigation and adequate, definitive treatment of enterococcal endocarditis to avoid the increased risk consequent on repeated courses of antibiotics. The resolution of the ototoxicity with netilmicin is consistent with other reports of lower cochleotoxicity than with other aminoglycosides.

Chronic Burkholderia multivorans bronchial infection in a non-cystic fibrosis individual with mannose binding lectin deficiency.

The case history is presented of a woman with multiple respiratory infections and mannose binding lectin (MBL) deficiency but no evidence of bronchiectasis who developed a chronic Burkholderia multivorans infection. Careful microbiological assessment is needed in patients with recurrent respiratory infection and the presence of B multivorans should trigger further immunological investigation including assessment of MBL status.

Guidelines for the antibiotic treatment of endocarditis in adults: report of the Working Party of the British Society for Antimicrobial Chemotherapy.

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.

Waterhouse-Friderichsen syndrome as a result of non-meningococcal infection.

Waterhouse-Friderichsen syndrome--massive adrenal haemorrhage in the setting of overwhelming clinical sepsis--is usually taken at necropsy to indicate meningococcal infection, and may be the only evidence of this pathogen. This report describes three fatal cases of the syndrome in which the causative organism proved to be a streptococcus. The organisms were detected during routine coroners' autopsies with histology and microbiological investigations. In two cases, the syndrome followed Streptococcus pneumoniae infection and in a third beta haemolytic streptococcus group A. Thus, adrenal haemorrhage alone cannot be taken to indicate meningococcal disease and other pathogens, particularly streptococcus, must be considered.

An investigation into causative factors in patients with bronchiectasis.

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.

An approach to the control of disease transmission in pig-to-human xenotransplantation.

Although several major immunologic hurdles need to be overcome, the pig is currently considered the most likely source animal of cells, tissues and organs for transplantation into humans. Concerns have been raised with regard to the potential for the transfer of infectious agents with the transplanted organ to the human recipient. This risk is perceived to be increased as it is likely that the patient will be iatrogenically immunocompromised and the organ-source pig may be genetically engineered in such a way to render its organs particularly susceptible to infection with human viruses. Furthermore, the risk may not be restricted to the recipient, but may have consequences for the health of others in the community. The identification of porcine endogenous retroviruses and of hitherto unknown viruses have given rise to the most concern. We document here the agents we believe should be excluded from the organ-source pigs. We discuss the likelihood of achieving this aim and outline the potential means by which it may best be achieved.

Parenteral ivermectin in Strongyloides hyperinfection.

Strongyloides hyperinfection, unresponsive to oral ivermectin and oral albendazole, was controlled by subcutaneous administration of a veterinary preparation of ivermectin.

Discrete-time stimulation of the oscillatory and excitable forms of a FitzHugh-Nagumo model applied to the pulsatile release of luteinizing hormone releasing hormone.

A model for the pulsatile release of luteinizing hormone releasing hormone (LHRH) can be reduced to a FitzHugh-Nagumo model subject to regular and quasiregular (i.e., with slight random variation in the interstimulus interval), discrete-time stimulation. The relationship of output pulse frequency (OPF) to stimulus frequency is compared between the excitable and oscillatory forms of the model and discussed in the context of results from other pulse-driven model systems. Some examples of the changes in OPF caused by quasiregular and purely Poissonian stimuli are given for the excitable case. The unstimulated system frequently interacts with the stimulation in such a complex manner that the OPF bears little resemblance to the frequency of stimulation or of the unstimulated system. Furthermore, the inability of the oscillatory form of the model to allow complete suppression of output pulses for moderate stimulation frequencies suggests that the LHRH system can be more appropriately described by the excitable form of the model. (c) 1995 American Institute of Physics.