Multicenter evaluation of the Abbott LCx Mycobacterium tuberculosis ligase chain reaction assay.

Four Australian hospital laboratories evaluated the performance of the Abbott LCx Mycobacterium tuberculosis assay with 2,347 specimens (2,083 respiratory and 264 nonrespiratory specimens) obtained from 1, 411 patients. A total of 152 specimens (6.5%) were culture positive for Mycobacterium tuberculosis complex (MTBC); of these, 79 (52%) were smear positive. After resolution of discrepant data, the overall sensitivity, specificity, and positive and negative predictive values for the LCx assay were 69.7, 99.9, 99.1, and 97.7% respectively. For smear-positive respiratory specimens that were culture positive for MTBC, the values were 98.5, 100, 100, and 98.4%, respectively, while the values for smear-negative respiratory specimens were 41.5, 99.9, 96.4, and 98%, respectively. Relative operating characteristic curves were constructed to demonstrate the relationship between sensitivity and specificity for a range of possible cutoff values in the LCx assay. These graphs suggested that the assay sensitivity for respiratory samples could be increased from 70.2 to 78.6%, while the specificity would be reduced from 99.9 to 99.4% by inclusion of a grey zone (i.e., LCx assay values of between 0.2 and 0.99). An algorithm is presented for the handling of specimens with LCx assay values within this grey zone.

Peritonitis associated with a CDC group EO-3 organism.

A 63-year-old female with chronic renal failure on continuous ambulatory peritoneal dialysis developed chronic peritonitis. A CDC group EO-3 organism was isolated from the peritoneal dialysis fluid on five occasions over a period of 4 months. This is the first reported isolation of this organism in which it is associated with a patient on continuous ambulatory peritoneal dialysis.

Meningococcal disease in urban south western Sydney, 1990-1994.

BACKGROUND: There has been a sustained increase in incidence of meningococcal disease throughout Australia since 1987. In south western Sydney the incidence is higher than the national rate and a cluster of cases occurred in 1991 resulting in a widespread vaccination programme. AIMS: To investigate the clinical demographics of patients with meningococcal disease treated in south western Sydney, and to differentiate meningococcal strains to understand better the epidemiology in this urban setting. In addition, to investigate whether delays in diagnosis of meningococcal disease and institution of appropriate treatment were occurring. METHODS: Retrospective classification of notified cases as meningitis, septicaemia, meningitis/septicaemia, and other syndromes. Clinical information recorded to establish patterns of disease, delays in diagnosis and appropriate treatment, and outcome. Microbiological classification of organisms isolated by serogroup, serotype and subtype. RESULTS: Meningococcal disease primarily affects young children in winter months in south western Sydney, with a secondary peak of incidence in the 15-20 year old age group. 20.7% presented with meningitis only, 22.4% with septicaemia only, and 53.4% with meningitis/septicaemia. There was a delay in diagnosis and institution of appropriate treatment of more than two hours in 21/58 (36.2%) patients including three of the six who died. No patient had received a parenteral antibiotic prior to coming to hospital -18.9% had received an oral antibiotic. The use of antibiotics before diagnostic lumbar puncture decreased the number of positive CSF cultures. However, in all but one patient with negative cultures there was other microbiological evidence of meningococcal disease. The mortality rate was highest (30.8%) in patients with septicaemia only, 6.5% in patients with meningitis/septicaemia and 0% in patients with meningitis only. Serogroup C was the predominant organism in all age groups. The predominant serotype was 2b (80% of serogroup C isolates). Subtypes were more variable but P1.2 occurred in 66.7% of serogroup C strains. CONCLUSIONS: There is a need for more education in our Health Area to improve the time taken to diagnose and institute appropriate treatment. The predominance of serogroup C is unusual in urban Australia where national data show serogroup B organisms predominate. Meningococci of phenotype C:2b:P1.2 have continued to cause disease in our Health Area for the past five years. This phenotype is uncommon in other areas of Australia.

Legionnaires' disease outbreak in south western Sydney, 1992. Clinical aspects.

OBJECTIVES: To document the clinical, laboratory and radiological features of patients with Legionella pneumophila serogroup 1 pneumonia during an outbreak, and probe for any relationship between clinical or laboratory features and outcome. DESIGN AND SETTING: Prospective identification of patients with Legionnaires' disease in an outbreak from 15-26 April 1992 in the South Western Sydney Area Health Service, centred on the Fairfield area. PATIENTS: Twenty-six patients (22 men, four women) were confirmed to have the disease, based on the presence of clinical features of pneumonia, with L. pneumophila serogroup 1 isolated on culture, or evidence of seroconversion. RESULTS: Seventeen patients (65.4%) were culture-positive for L. pneumophila serogroup 1 and nine were diagnosed on serological criteria. A direct fluorescent antibody (DFA) test of sputum performed well as a rapid diagnostic method. Twenty-three patients (89%) presented with hyponatraemia, 14 (54%) with renal impairment and nine of 19 (47%) with elevated serum creatinine phosphokinase levels. Overall mortality was 23% (71% for patients requiring mechanical ventilation). Eleven of 119 patients (10.2%) who did not have Legionnaires' disease showed serological evidence of previous exposure. CONCLUSIONS: The duration of symptoms and severity of biochemical abnormalities at presentation were not related to outcome. The sputum DFA test is useful for rapid diagnosis during outbreaks.

M-6 endocarditis: report of an Australian case.

Neisseria elongata subsp. nitroreducens (formerly CDC group M-6) is a newly-recognized cause of particularly destructive endocarditis, frequently requiring valve replacement. We describe an Australian case of endocarditis caused by this organism, summarizing the clinical and microbiological features of this rarely isolated subspecies.

Infective endocarditis due to nontoxigenic Corynebacterium diphtheriae: report of seven cases and review.

We report seven cases of endocarditis due to nontoxigenic Corynebacterium diphtheriae that occurred between October 1990 and September 1991. The patients all lived in the state of New South Wales, Australia. Three patients had preexisting cardiac abnormalities, and one patient used intravenous drugs regularly. The other three patients had no known risk factors for endocarditis. Notable clinical features were the aggressive nature of the infection, the occurrence of septic arthritis in four patients, and major vascular complications in four patients, one of whom died. One patient required urgent mitral valve replacement. All of the isolates were identified as non-toxigenic C. diphtheriae var gravis. Sporadic cases of endocarditis due to C. diphtheriae have rarely been reported; septic arthritis complicating endocarditis due to this organism has not previously been described. This report highlights the importance of identifying Corynebacterium isolates from normally sterile sites at the species level.