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Biomedical subjects

J H Hewitt

Publications and source records attributed to J H Hewitt.

18 recordsLinked to original sources
PubMed1990

The efficacy of chlorination and filtration in the control and eradication of Legionella from dental chair water systems.

The apparent failure of hyperchlorination and continuous dosing with chlorine to eliminate legionellae from a dental teaching hospital water supply prompted a prospective study to evaluate charcoal filters as a means of decontamination. Legionella pneumophila serogroup 10 and L. bozemanii serogroup 2 were isolated from dental units yielding 10(1)-10(3) colony forming units (cfu) ml-1 with total bacterial counts in the range 10(2)-greater than 10(4) cfu ml-1. After chair-side installation of charcoal filters bacterial contamination of the dental unit water was prevented and legionellae were initially not detected, but after 7 days the total count returned to pre-filtration levels of greater than 10(4) cfu ml-1; L. pneumophila serogroup 10 was eliminated but L. bozemanii serogroup 2 persisted. These results suggest that neither chlorination nor charcoal filtration deal adequately with the potential hazard of Legionella spp. in dental water.

Charcoal↗
PubMed1986

Large outbreaks of Clostridium perfringens food poisoning associated with the consumption of boiled salmon.

Five large outbreaks of food poisoning are described in which clinical, epidemiological or laboratory data indicated Clostridium perfringens as the causative organism. The foodstuff common to all incidents was boiled salmon served cold as an hors d 'oeuvre. In all cases the fish had been subject to a long period of cooling or storage between boiling and consumption. It is thought that multiplication of the organism occurred during this time. Recommendations are made for the avoidance of further similar incidents.

Animals↗
PubMed1978

Organisation of bank of raw and pasteurised human milk for neonatal intensive care.

In 1976 a human-milk bank was established at King's College Hospital to serve the neonatal intensive care unit. The bank is staffed by two part-time nurses, who interview prospective donors, organise collections, prepare samples for bacteriological screening, and process the milk. On average 25 litres a month may be collected from about 15 donors, of which at least two-thirds is free enough of bacteria to be fed raw (unheated) to sick and low-birth-weight infants. Most of the remainder may be used after holder pasteurisation. The bank provides an adequate supply of milk of consistent nutritional quality and permits a more informed approach to the dietary management of infants of low birth weight.

Costs and Cost Analysis↗
PubMed1976

Effect of various milk feeds on numbers of Escherichia coli and Bidifobacterium in the stools of new-born infants.

Escherichia coli was found in a similar proportion of stool specimens from infants who were breast-fed and from others fed on three different artificial-milk preparations. When E. coli was present its mean colony count in the stools of breast-fed infants was within the range of the mean counts for infants receiving the artificial -milk feeds. There was no consistent relation between high counts of bifidobacteria (Lactobacillus bifidus) and low counts of E. coli. This suggests that measures aimed at implanting or stimulating the growth of bifidobacteria in the large intestine of artificially fed infants may not greatly influence the E. coli population therein. The results are discussed in relation to the protection of artifically fed infants from E. coli enteritis.

Animals↗
PubMed1970

Nasal acquisition of Staphylococcus aureus in a subdivided and mechanically ventilated ward: endemic prevalence of a single staphylococcal strain.

An investigation was made of nasal acquisition of Staphylococcus aureus and of staphylococcal wound sepsis in a hospital ward divided into two sections and provided with mechanical ventilation, so that there was no transfer of air from one of the sections to the other. Although the strains of S. aureus found in the air, and those colonizing the noses of patients, in the protected section could seldom be related to patients nursed elsewhere in the ward, the mechanical ventilation did not lead to any significant reduction in the degree of contamination of the air or in the rate of nasal acquisition of S. aureus.Even in the protected section, nearly 20% of the strains of S. aureus recovered from the air could not be related to known nasal carriers. Since this proportion was nearly as great as that found in the absence of directed air-flow, it seems probable that these strains were derived either from undetected sources within the section or were dispersed from the clothes of persons who entered it.Nearly one-third of the nasal acquisitions in the ward could not be related to known nasal carriers, but about one-half of these (16%) were probably ;spurious' and half of the remainder (8%) could be related to strains recovered from patients' lesions or drawsheets, leaving no more than 8% unaccounted for. A short investigation in which both drawsheet and perineal samples were examined showed that drawsheet samples did not give a reliable indication of perineal carriage unassociated with nasal carriage.During the period of the investigation, a single strain of S. aureus that was resistant to a wide range of antibiotics established itself in the ward. The most notable character of this strain was the profuse dispersion of it by carriers. As a consequence, staphylococcal wound sepsis increased, with nearly three-quarters of the infections attributable to this strain, and nasal carrier rates increased with length of stay in the ward, over 20% of patients who stayed 5-6 weeks acquiring the strain.

Air Microbiology↗
PubMed1968

Sensitivity of penicillinase-forming strains of Staphylococcus aureus and of their penicillinase-negative variants to cephaloridine, cephalothin, methicillin, and benzylpenicillin.

Twenty-eight penicillinase-forming cultures of Staphylococcus aureus and their penicillinase-negative variants were examined for resistance to benzylpenicillin, methicillin, cephalothin, and cephaloridine. The results supported the view that cephaloridine was more easily destroyed by staphylococcal penicillinase than was cephalothin. In our tube-dilution tests, the minimum inhibitory concentration (M.I.C.) of cephaloridine for methicillin-sensitive cultures was never as high as some of the values reported by other workers who used apparently comparable methods. This was probably due to small differences in technique. The M.I.C. is an unsatisfactory measure of the antibiotic sensitivity of an organism which produces an enzyme which destroys the antibiotic.Methicillin-resistant strains of Staph. aureus have an intrinsic resistance of ;heterogenous' type also to benzylpenicillin, cephalothin, and cephaloridine.

Cephaloridine↗