Floristic evidence for alternative biome states in tropical Africa.

The idea that tropical forest and savanna are alternative states is crucial to how we manage these biomes and predict their future under global change. Large-scale empirical evidence for alternative stable states is limited, however, and comes mostly from the multimodal distribution of structural aspects of vegetation. These approaches have been criticized, as structure alone cannot separate out wetter savannas from drier forests for example, and there are also technical challenges to mapping vegetation structure in unbiased ways. Here, we develop an alternative approach to delimit the climatic envelope of the two biomes in Africa using tree species lists gathered for a large number of forest and savanna sites distributed across the continent. Our analyses confirm extensive climatic overlap of forest and savanna, supporting the alternative stable states hypothesis for Africa, and this result is corroborated by paleoecological evidence. Further, we find the two biomes to have highly divergent tree species compositions and to represent alternative compositional states. This allowed us to classify tree species as forest vs. savanna specialists, with some generalist species that span both biomes. In conjunction with georeferenced herbarium records, we mapped the forest and savanna distributions across Africa and quantified their environmental limits, which are primarily related to precipitation and seasonality, with a secondary contribution of fire. These results are important for the ongoing efforts to restore African ecosystems, which depend on accurate biome maps to set appropriate targets for the restored states but also provide empirical evidence for broad-scale bistability.

Use of the BioMerieux ID 32C yeast identification system for identification of aerobic actinomycetes of medical importance.

The BioMerieux ID 32C Yeast Identification System was examined to determine its usefulness as a rapid method for the identification of medically important aerobic actinomycetes. More than 290 strains were tested by this method and the results were compared to those obtained by conventional methods. It was found that aerobic actinomycetes could be differentiated to species level in 7 days by the ID 32C system.

Paecilomyces variotii in peritoneal dialysate.

Four cases of peritonitis caused by the filamentous fungus Paecilomyces variotii in patients on continuous ambulatory peritoneal dialysis are reported. Removal of the Tenckhoff catheter and antifungal chemotherapy led to resolution of symptoms in all cases. Possible contaminating events are discussed, and reported infections with P. variotii are reviewed.

Blood-culture techniques. A survey in Australasian laboratories.

The blood-culture methods of participants in the Microbiology Quality Assurance Programme were surveyed in late 1983; 183 participants from Australasia and S.E. Asia completed a questionnaire, the results of which are discussed. The choice of skin disinfectants varied widely. Conventional broth media were used by 85 participants; one or more diphasic bottles by 56; Roche Septi-Chek was used by 25; and BACTEC by 17. Only 80% of respondents reported the use of sodium polyanethol sulfonate. Contamination rates ranged from 0 to greater than 10%. Cultures were kept for as little as five days or as long as three weeks and were examined by inspection and/or Gram stain and/or subculture at widely varying intervals. While a great diversity of methods was used, in most cases these were adequate. The workload involved in some of the more laborious routines was considerable. It would be desirable to evaluate the cost-effectiveness of many blood culture practices.

Black fungi: a survey of dematiaceous hyphomycetes from clinical specimens identified over a five year period in a reference laboratory.

Five hundred and fifty six dematiaceous hyphomycetes, the great majority referred from other laboratories, were identified by us over a five year period. Of these, thirty five were regarded as being of probable pathogenetic significance. These included seven isolates associated with chromoblastomycosis, and seven isolates thought to be causing phaeohyphomycosis. There were six strains of Phaeoannellomyces werneckii and five strains of Sporothrix schenckii. Seven isolates, all strains of Aureobasidium pullulans, were associated with fungal peritonitis in patients on chronic ambulatory peritoneal dialysis. Two Bipolaris isolates were associated with paranasal sinus fungus ball, a condition in which no evidence of tissue invasion by fungi could be found, even though pressure necrosis of bone could lead to very serious consequences. A further seven dematiaceous hyphomycetes, isolated from cases of paranasal fungus ball, keratitis and otitis externa, were thought to be of possible pathogenetic significance. Of the remaining 514 isolates thought to be of no pathogenetic significance, two thirds were made up of strains of Aureobasidium pullulans, Alternaria alternata, Cladosporium cladosporioides, Epicoccum purpurascens and Phoma species. In many cases it was thought that the referring laboratories had allowed insufficient time for development of conidiogenesis in these strains, before sending them to our laboratory for identification.

Subcutaneous zygomycosis due to Saksenaea vasiformis in an infant.

A case of localized, subcutaneous infection in the cheek of a three-month-old girl that was caused by the zygomycete Saksenaea vasiformis is reported. This is the fourth report of infection in Australia that was due to this fungus and, in contrast to all but one of the few previous reports in the literature, a cure was effected by surgical debridement alone.

Trichosporon beigelii: survey of isolates from clinical material.

Two hundred and eight isolates of Trichosporon beigelii were identified over the period January 1973 to July 1983. 45.7% of these were from skin, 25.0% from nail, 22.6% from tissues and fluids, 3.4% from hair and 3.4% from sputum. Tr. beigelii was isolated in association with a recognized pathogen in 23 cases, 9 with a yeast, 14 with a dermatophyte. In 38 cases, Tr. beigelii was the only organism isolated when direct microscopic examination of clinical material showed the presence of hyphae and/or yeast cells. Although Tr. beigelii could only be assigned a definite pathogenic role in 6 cases of genital white piedra, and in one case of peritonitis associated with chronic ambulatory peritoneal dialysis, we believe that this organism was pathogenic in many cases of skin infection. In most of the cases where it was isolated from tissue or fluids at Royal North Shore Hospital, Tr. beigelii was not considered to be significantly contributing to the disease process.

Histoplasma capsulatum. Isolation from an Australian cave environment and from a patient.

The fungus Histoplasma capsulatum, although commonly found in bat-frequented caves in many countries, has not previously been isolated from that environment in Australia. This report describes the isolation of H. capsulatum from several sources, including cave soil, the organs of mice exposed to the cave environment, and the sputum of a patient clinically diagnosed as having acute pulmonary histoplasmosis after exposure to the cave environment.

Salmonella food poisoning.

During an outbreak of Salmonella typhimurium food poisoning in September 1983, in Sydney, 10 affected subjects were admitted to the same hospital. On admission to hospital, all patients were severely dehydrated; two patients developed acute tubular necrosis, while a third patient had myopericarditis. Bacteraemia was confirmed in two patients, in one of whom no organisms were isolated from stool cultures. Antibiotic agents were administered to all patients, because of the unusually severe nature of the infection. This outbreak illustrates that salmonella gastroenteritis, although usually fairly mild and self-limiting, can be a virulent disease resulting in serious complications. Appropriate management should include careful initial assessment of suspected cases, vigorous correction of fluid and electrolyte disturbances, and judicious use of antibiotic agents when bacteraemia or severe toxaemic features are present.

External quality assurance in microbiology. The programme of the Royal College of Pathologists of Australasia.

Since 1967 the Royal College of Pathologists of Australasia has been providing an external quality assurance programme in microbiology. The number of participants has risen from 70 to 222, and the samples distributed for investigation have increased in quantity, now totalling 35-40 per annum, and in variety, so that most aspects of clinical microbiology are now touched on. In recent years clerical accuracy and the adequacy of reports have been examined. However, more emphasis is needed on the stability of the specimens (freeze-drying will be introduced soon), the assessment of a laboratory's general performance, the standardization of methods and the educational aspects of external quality control.

Clinching the diagnosis--sputum and other specimens in respiratory tract infection.

Routine sputum culture in microbiology laboratories is frequently a source of dissatisfaction to microbiologists and clinicians alike. Care should be taken to ensure that the investigations requested are appropriate and that an adequate specimen is collected. Co-operation between the microbiologist and the clinician is required if the laboratory's facilities are to be properly exploited for the etiological diagnosis of respiratory tract infection. In clinical conditions such as lung abscess and atypical pneumonia sputum is not an appropriate specimen for the laboratory to work on and early consideration should be given to obtaining lower respiratory tract secretions free of oropharyngeal contamination.

Dermatophytes identified at the Australian National Reference Laboratory in Medical Mycology 1966-1982.

Over a 17 yr period from 1966 to 1982, 4354 dermatophytes were identified at the Australian National Reference Laboratory in Medical Mycology. The most frequently identified species was Trichophyton rubrum, accounting for 35.3% of identifications, followed by Trichophyton mentagrophytes (26.5%), Trichophyton tonsurans (12.8%), Epidermophyton floccosum (10.7%) and Microsporum canis (8.4%). Specimens taken from the feet were the most common source of the Trichophyton rubrum isolates, followed by specimens from the groin. The highest incidence of T. rubrum and other Trichophyton infections was found in males in the age group 21-30 yr. Microsporum species were most commonly isolated from children aged 10 yr or less. In 1.5% of specimens, more than one fungal species was isolated. In most of these instances a yeast (predominantly Candida species) was found in addition to a Trichophyton species.