A field study of the survival of Legionella pneumophila in a hospital hot-water system.

The colonization, survival and control of Legionella pneumophila in a hospital hot-water system was examined. The organism was consistently isolated from calorifier drain-water samples at temperatures of 50 degrees C or below, despite previous chlorination of the system. When the temperature of one of two linked calorifiers was raised to 60 degrees C, by closing off the cold-water feed, the legionella count decreased from c. 10(4) c.f.u./l to an undetectable level. However, 10 min after turning on the cold-water feed which produced a fall in calorifier temperature, the count in the calorifier drain water returned to its original level. Investigations revealed that the cold-water supply was continually feeding the calorifiers with L. pneumophila. Simple modifications in the design of the system were made so that the cold-water feed no longer exceeds 20 degrees C; these measures have considerably reduced the number of L. pneumophila reaching the calorifiers.

The Stafford outbreak of Legionnaires' disease.

A large outbreak of Legionnaires' disease was associated with Stafford District General Hospital. A total of 68 confirmed cases was treated in hospital and 22 of these patients died. A further 35 patients, 14 of whom were treated at home, were suspected cases of Legionnaires' disease. All these patients had visited the hospital during April 1985. Epidemiological investigations demonstrated that there had been a high risk of acquiring the disease in the out patient department (OPD), but no risk in other parts of the hospital. The epidemic strain of Legionella pneumophila, serogroup 1, subgroup Pontiac 1a was isolated from the cooling water system of one of the air conditioning plants. This plant served several departments of the hospital including the OPD. The water in the cooling tower and a chiller unit which cooled the air entering the OPD were contaminated with legionellae. Bacteriological and engineering investigations showed how the chiller unit could have been contaminated and how an aerosol containing legionellae could have been generated in the U-trap below the chiller unit. These results, together with the epidemiological evidence, suggest that the chiller unit was most likely to have been the major source of the outbreak. Nearly one third of hospital staff had legionella antibodies. These staff were likely to have worked in areas of the hospital ventilated by the contaminated air conditioning plant, but not necessarily the OPD. There was evidence that a small proportion of these staff had a mild legionellosis and that these 'influenza-like' illnesses had been spread over a 5-month period. A possible explanation of this finding is that small amounts of aerosol from cooling tower sources could have entered the air-intake and been distributed throughout the areas of the hospital served by this ventilation system. Legionellae, subsequently found to be of the epidemic strain, had been found in the cooling tower pond in November 1984 and thus it is possible that staff were exposed to low doses of contaminated aerosol over several months. Control measures are described, but it was later apparent that the outbreak had ended before these interventions were introduced. The investigations revealed faults in the design of the ventilation system.

A christening party outbreak of haemorrhagic colitis and haemolytic uraemic syndrome associated with Escherichia coli O 157.H7.

A point source outbreak of haemorrhagic colitis due to Escherichia coli O 157.H7 producing verocytotoxin (VT), took place following a christening party in Birmingham in June 1987. Twenty-six people were affected, six were admitted to hospital and one developed haemolytic uraemic syndrome: there were no deaths. VT + E. coli O 157.H7 was isolated from 13 (57%) of 23 faecal specimens from affected people and from 3 (9%) of 33 specimens from asymptomatic people. Free VT was detected in the faeces of one further asymptomatic person. Illness was associated with eating turkey-roll sandwiches (P less than 0.001) suggesting that cold meats might be an important source of infection.

Factors affecting growth of Legionella pneumophila in liquid media.

The growth in liquid media of Legionella pneumophila serogroups 1-6 was monitored turbidimetrically and factors affecting growth rate were studied. The presence of inhibitors, use of detoxifying agents and the method of broth preparation each had significant effects on cultivation. Cysteine was essential for growth; the optimal concentration was 100 micrograms/ml, but supplemental iron had no demonstrable effect.

The activity of imipenem on Legionella pneumophila, with a note on the treatment of two cases.

An in-vitro assessment of the activity of imipenem, a new carbapenem beta-lactam antibiotic, was undertaken on isolates of Legionella pneumophila. The minimum inhibitory concentrations of imipenem were in the range 0.03 to 0.25 mg/l and turbidimetric studies showed that imipenem had a marked bactericidal effect which was more pronounced than that seen with either rifampicin or erythromycin. Two patients with legionella pneumonia were successfully treated with imipenem as part of a clinical trial of the drug.

Failure of the hydrogen breath test to detect pulmonary sugar malabsorption.

Five patients with sucrase-isomaltase deficiency, and one patient with primary glucose-galactose malabsorption had no increases in breath hydrogen excretion after oral sucrose or glucose. Anaerobic incubation with sugars of stool suspensions from 5 patients with primary sugar malabsorption produced by trace of hydrogen (17 microliter) in only one, while those from 13 or 14 controls produced a mean hydrogen volume of 640 microliter under similar conditions. Altered bacterial metabolism is a probable explanation. Breath hydrogen excretion did increase appreciably in 2 of these patients after oral lactulose showing that hydrogen excretion may vary according to the substrate. Therefore, observation of breath hydrogen excretion after lactulose is not recommended as a means of predicting false-negative breath tests with other sugars. The hydrogen breath test is not a reliable mean of diagnosing primary sugar malabsorption in children.

Infective endocarditis caused by Streptococcus mutans.

Members of the viridans group of streptococci are the commonest causes of bacterial endocarditis. However, Streptococcus mutans, a member of this group associated with dental caries which might be expected to be commonly associated with endocarditis, has only rarely been reported. This is possibly because of difficulties in isolation and identification. Differing blood culture media may affect the chances of isolation of these organisms, and, though brain-heart infusion, thiol, tryptic soy, and glucose-brain infusion broths have all proved satisfactory, subcultures may require increased CO2 concentrations for growth. Plemorphism in the resultant colonies and in the individual organisms may give rise to a hazardous misinterpretation of this appearance as contamination. Strep. mutans and the similarly penicillin sensitive Strep. bovis may be differentiated from the penicillin resistant enterococci by their lincomycin sensitivity and intolerance of 6-3 per cent sodium chloride. Precise differentiation of streptococci in bacterial endocarditis is of value both epidemiologically and in the management of the disease.

The adherence of pilate and non-pilate strains of Neisseria gonorrhoeae to human and guinea-pig epithelial tissues.

Strains of Neisseria gonorrhoeae adhered to pieces of human endocervix and appeared to be embedded in the surface mucus. Although a pilate strain adhered better than a non-pilate strain, the difference was small and pilation did not appear to be exclusively responsible for adherence. The pilate strain showed better adherence to pieces of human ectocervix and fallopian tube, but both strains were similarly adsorbed to human bronchus and guinea-pig uterus, cervix, male urethra and bladder, although to different degrees for different tissues. Since gonococci adhered to all tissues examined, their ability to infect human endocervix and fallopian tube and their failure to infect human ectocervix or guinea-pig urogenital tract mucosae are determined by factors other than a capacity for primary adherence to the tissue.

Clinical trial of mebendazole, a broad-spectrum anthelminthic.

Eighty-five children aged 5-14 years who were infested with worms were treated with mebendazole 100 mg twice daily for three days. The percentage cure rates were ascaris 100%, trichuris 94%, hookworm 82%, and hymenolepis 39%. The drug was well tolerated and with its broad activity should be very useful in treating those with multiple infestations.

Characteristics of some co-trimoxazole-resistant Enterobacteriaceae from infected patients.

Two isolates of Proteus mirabilis and four of Esch. coli which would not grow on commonly used commercial sensitivity test media are reported. These organisms appear to be resistant to co-trimoxazole, are exacting towards thymidine, and five of six were isolated from patients who had been treated with co-trimoxazole. A method for the detection of these strains is given and their significance in the laboratory and clinical practice discussed.

Stimulation of growth on a deficient medium of a Klebsiella aerogenes species by sulphonamide, para-amino benzoic acid, nitrofurantoin, and some other substances.

A strain of Klebsiella aerogenes is described which was unable to grow from light inocula on 5% lysed horse blood diagnostic sensitivity test (DST) agar. It was able to grow on DST agar without added horse cells and MacConkey and nutrient agar. Growth on a deficient medium was promoted by sulphonamides and nitrofurantoin as well as by para-amino benzoic acid, para-amino salicylic acid, procaine hydrochloride, thymine, and uracil.

Survey of intestinal pathogens from immigrant children.

Four thousand immigrant schoolchildren were screened by using a concentration method on a single faecal specimen for intestinal helminths; 1,468 (37%) were positive. Carriage rates were highest (51%) in children from the West Indies, in whom trichuris (75% of carriers) and ascaris (40% of carriers) predominated; carriage of two or more species was common (36% of carriers). Carriage of worms was low in children from Kenya (16%) and Uganda (7%). Children from South-east Asia, predominantly from India and Pakistan, had carriage rates between 30 and 40%; girls and boys from Pakistan differed significantly in their carriage patterns of hook-worm (commoner in boys) and hymenolepis and ascaris (commoner in girls).Five salmonellas were found, two of which were Salmonella typhi, and five Shigella sonnei were isolated. No isolates were made of Vibrio cholerae (classical or El Tor biotypes) from 590 South-east Asian children.