Mair Thomas

Sonne dysentery in day schools and nurseries: an eighteen-year study in Edmonton.

A study of Sonne dysentery infections in 19 primary and 11 secondary day-schools and 4 day-nurseries has been made over a period of 18 years in an urban area. Measures were taken throughout to try to prevent and control outbreaks. Sonne dysentery was not endemic in the school population and, even at times of high incidence, epidemics were localized within a few of the primary schools, usually in the spring or autumn terms. Incidence rates of Sonne dysentery were highest in primary schools with large infant departments and in nurseries. Secondary schools entirely escaped outbreaks.The co-operation of head teachers was engaged for all precautionary measures in schools. A policy of immediate exclusion of suspected and infected children was useful in preventing and controlling school epidemics of dysentery. Toilet hygiene was often poor in schools with outbreaks, and this was found to be a profitable field for applying control measures. Infected kitchen workers were only occasionally involved.Recommendations are given in the light of this study, and some reference is made to the more difficult problem posed by dysentery outbreaks in day-nurseries, where temporary closure may be the best policy. It is important that responsibility for infectious disease control in schools be clearly delineated in the reorganized health services of 1974. Teachers can play an important part in limiting infection.

Studies on a CO2-dependent Staphylococcus

A dwarf strain of Staphylococcus aureus was isolated in pure culture from styes on the eyelid of a young woman. Incubation of pus cultured on horse blood agar in 5% CO2 yielded a typical golden staphylococcus, coagulase and catalase positive and penicillin sensitive, but on duplicate plates in air the growth was of tiny white colonies only 0.25 mm. in diameter. These were penicillinsensitive Gram-positive cocci, but the catalase and coagulase tests were negative. Subcultured with added C02, typical 2 mm. colonies of Staphylococcus aureus developed, but in air all grew as dwarfs. This coccus was of bacteriophage type 52A. The patient, who had used penicillin ointment, was now given systemic penicillin and her styes healed, but the dwarf staphylococcus was present in nasal swabs a month later. Swabs from her mother, who had a palmar abscess and then a sore throat, also yielded a dwarf staphylococcus of type 52A which required added CO2 for normal growth.

DERMAL TRANSMISSION OF VIRUS AS A CAUSE OF SHINGLES

Abstract Three cases of adult shingles and one of childhood chickenpox were linked by visits to a single household. The shingles appeared 2-5 weeks after brief but close exposure to infection. It is concluded that shingles is not invariably due to reactivation of latent virus but can also follow recent infection, and it is suggested that this may occasionally be through the skin. Antihistamines may possibly join other immunosuppressive agents as a predisposing agent.

Salmonellosis in general practice. Observations of cases and their households in Enfield

Nine hundred and seventeen Salmonella infections in 580 households were confirmed during a laboratory study of diarrhoea in general practices in a large urban area during the years 1953-68. This was an annual incidence of about 2/10,000 population. Salmonellas were found in nearly 2% of new cases of diarrhoea investigated. Plural infections were found in 36% of the households studied and 18% of all contacts examined were shown to be infected. Among these contacts the infection rate was higher for children (24%) than for adults (16%). The duration of infection was longer than 2 months in nearly a quarter of the cases followed up, and intermittent excretion was observed in one-fifth. The commonest serotype was Salmonella typhimurium, but its incidence in the district declined especially after 1964. S. typhimurium infection provoked a severer enteritis but less general symptoms than did other salmonellas. Children were more susceptible than adults to salmonella infection, to illness and to prolonged excretion, but symptoms in index cases were as severe in adults as in children.

Contamination of an operating theatre by Gram-negative bacteria. Examination of water supplies, cleaning methods and wound infections

This paper describes a search for Gram-negative bacteria in an operating theatre and the steps taken to reduce the level of environmental contamination.A high rate of infection in clean wounds prompted a bacteriological survey. Potential sources of infection found, and the measures employed are described in the hope that others may be encouraged to examine familiar equipment critically and to improve hygiene even in old premises.The choice, design, use and care of cleaning and sterilizing equipment were open to criticism. In particular, a currently popular floor-scrubbing machine provided a breeding ground for Pseudomonas aeruginosa and was distributing it in the theatre environment.

HOSPITAL OUTBREAK OF CLOSTRIDIUM PERFRINGENS FOOD-POISONING

An outbreak of Clostridium perfringens (C.welchii) food-poisoning affected a third of the patients in a large hospital, and one frail patient died. C.perfringens type A, serotype 1, was isolated from 46 (61 per cent) of 76 patients examined and from food, and a new serotype (61) was isolated from 16. The attack-rate among patients who ate a minced-ham dish was 78 per cent. The cooking and storage of this mince was faulty: cuts of meat were much too large, they were kept at room temperature too long before refrigeration, and after cooking they were put into mincers used also for raw meat. C.perfringens type A, serotype 1, was isolated from meat scraps in a mincer. Final reheating was inadequate to destroy even vegetative bacteria, and multiplication may have occurred during slow distribution to the wards. Outbreaks of C.perfringens fool-poisoning are common in hospitals, and some underlying problems are discussed. A plea is made for the Food Hygiene Regulations to apply to National Health Service premises and for simple but effective reforms in institutional catering management.

EPIDEMIC OF POSTOPERATIVE WOUND INFECTION ASSOCIATED WITH UNGLOVED ABDOMINAL PALPATION

Abstract A small outbreak of wound infection among gynaecological patients followed an inadvertent change in operating-theatre practice. New medical students and housemen were found to have carried into the theatre the outpatient practice of gloving only the right hand for vaginal examination while palpating the abdomen with the bare left hand. Wounds were infected with a variety of different phage types of Staphylococcus aureus and with other bacteria. A similar range of organisms was isolated from the fingertips of students, nurses, and doctors. Staph. aureus was found on fingerprint cultures of 5 of 11 (46%) medical students, 5 of 16 (31%) nurses, and 3 of 19 (16%) medical staff, 2 being anaesthetists. Nasal carriage was even commoner, and heavy scalp carriage was found in two theatre workers and a student. Chlorhexidine nasal cream and hexachlorophane shampoo at least temporarily eliminated staphylococci from operating-theatre staff. The gloving and handwashing of all persons touching the abdomen in the theatre were supervised, and the cleansing of the skin before and after surgical incision was revised to eliminate the use of an unsterile cetrimide preparation. The outbreak ceased as soon as these measures were implemented.

An epidemiological study of strains of Shigella sonnei from two related outbreaks

During the winter of 1967-8 Sonne dysentery affected neighbouring North London primary schools. This was not simply due to cross-infection between the two schools, for two different, unusual strains of Sh. sonnei were distinguished. One was a novel kanamycin-resistant colicine type 7 strain, and as far as we know this was the first school outbreak due to such a strain to be documented. The other strain was kanamycin-sensitive and of colicine type 0 with a rare specific requirement for aspartic acid. There was some evidence to suggest that the kanamycin-resistant strain was more infective for adults and possibly more pathogenic than the kanamycin-sensitive.Studies on the transfer of drug resistance and of colicinogeny revealed that the factor determining colicine type 7 was carried on a transmissible plasmid, a new observation. Various drug resistances were also transmissible experimentally, and some were spontaneously unstable. Non-transferable ampicillin-resistance in the colicine type 7 strain and aspartic acid dependence in the colicine type 0 strain enabled all but one of the isolates to be classified into two distinct lines. No common ancestor was found and it was concluded that although occurring together they must have arisen from separate sources.

Virus diarrhoea associated with pale fatty faeces.

Steatorrhoea was a significant feature in an outbreak of rotavirus gastroenteritis which affected adults and infants in hospital. Fat globules or fatty acid crystals were obvious by light microscopy (LM) in faeces from 14 of 25 patients examined. Ten of the fatty stools and two of the remainder were very pale. By electron microscopy (EM) a rotavirus was seen in 11 of the 14 fatty faeces and in only two of 11 specimens without visible fat. In a further study of pale or fatty faeces 20 such specimens sent for laboratory examination from patients not involved in the hospital outbreak were compared microbiologically with a similar number which were neither pale nor fatty. Viruses were found by EM in 11 (55%) of the pale or fatty stools; eight rotaviruses, two astroviruses and an uncultivable adenovirus were seen; one further patient had acute jaundice. In contrast, no viruses were seen by EM in the twenty specimens which were normally pigmented and without evident fat. Steatorrhoea was significantly associated with rotavirus infection of the alimentary tract which usually presented as a fatty enteritis. We conclude that rotaviruses certainly, and other viruses possibly, can impede both the digestion of fat and the pigmentation of the faeces. Inspection and LM of faeces are easy. In acute enteritis a fatty or pale stool is an indication for virological examination.

Monitoring infectious diseases using routine microbiology data I. Study of gastroenteritis in an urban area

Sources of information for monitoring infectious disease are routine data, special surveys and ad hoc investigations. In practice much use is necessarily made of routine notifications and laboratory records although this reporting is often incomplete and may therefore be biased. In a retrospective study of a 16-year series (up to 1968) of routine records concerning the diagnosis of gastroenteritis at one Public Health Laboratory we found it possible to identify biases. During school outbreaks of dysentery, laboratory investigation of diarrhoea increased appreciably and such response to publicity affects the use of routine data in surveillance. Although the patients examined were probably representative diagnostically, their selection may not have reflected the age incidence of disease. Valid geographical comparisons within the urban area were not feasible because medical practitioners differed in their use of laboratory facilities and in their habits of notification. Nevertheless, as far as can be established retrospectively, these data did reflect time trends in disease incidence and so had value for monitoring purposes. Several of the biases defined are likely to apply to other sets of routine data. A further communication will describe a statistical method of correcting for quantifiable bias.