The occurrence of resistance to gentamicin in strains of Staphylococcus aureus with different phage patterns in two hospitals is described. The data suggest transfer of gentamicin resistance between different strains. In the strains investigated the determinant for resistance to gentamicin (parallel resistance to kanamycin and tobramycin) is located on the chromosome. The transfer of this resistance determinant in a mixed culture of donor and recipient cells in vitro is mediated by transduction because it is dependent upon lysogenicity of the donor for a serogroup-B phage and because it can be inhibited by γ-globulin. The transfer is always associated with lysogenization of the recipient cells by this phage.

Corynebacterium diphtheriae was first observed by Klebs in 1883 and was cultivated a year later by Loeffler, whose description in 1884 of the causative organism of diphtheria remains a standard. Diphtheria was a life-threatening disease throughout the world until the therapeutic use of antitoxin and the use, as a public health measure, of childhood immunization with toxoid. In Britain the use of toxoid was advocated by the Ministry of Health in the early 1920s, but it was not until 20 years later that extensive programmes of prophylaxis were carried out under the advertising campaign Diphtheria is Deadly.

Friedrich Loeffler's classical paper entitled ‘Untersuchungen über die Bedeutung der Mikroorganismen für die Entstehung der Diphtheric beim Menschen, bei der Taube und der Kalbe’ (Studies on the significance of bacteria in causing diphtheria in man, pigeons and calves), was published in 1884. In this paper and those which followed during the next few years, Loeffler described the diphtheria bacillus and its isolation in pure culture, and proved its relationship to the disease diphtheria. While the credit for the discovery of diphtheria toxin must go to Roux & Yersin (1888), Loeffler clearly predicted its existence in his original paper. Because, at autopsy, living ‘virulent’ diphtheria bacilli could only be recovered from experimental animals at the site of injection, Loeffler postulated that the bacteria must have released into the bloodstream a ‘chemical poison’ which caused the characteristic sterile haemorrhagic lesions in remote organs. He even noted early in 1888 that ‘the bacterial poison resembles in its action the poison [now known as abrin] obtained from jaquiriti seeds, which causes inflammation and the production of false membranes when placed on the mucous membranes either of men or animals’ (cited in Loeffler, 1908). Today we know the reason for this astute observation. Both abrin and diphtheria toxin block protein synthesis in sensitive eucaryotic cells (Collier, 1975; Olsnes & Pihl, 1976; Pappenheimer, 1977), albeit by different mechanisms. Almost a quarter of a century after the discovery of the diphtheria bacillus, the British Medical Research Council published a 718-page volume on diphtheria. In the first chapter Loeffler (1908) reviewed the history of the disease and reminisced at some length about his own early work. By 1908 when this book appeared, a good deal was already known about the epidemiology of diphtheria, the bacteriology of the diphtheria bacillus, its mode of spread by healthy adults and the protective effect of antitoxin. However, other than its proteinaceous nature almost nothing was known of the chemistry of diphtheria toxin or its mode of action. The interpretation of many of Loeffler's astute early observations and questions that puzzled him remained obscure and unanswerable until the discovery of lysogenic conversion to toxinogenicity by Freeman (1951) and the realization that the tox structural gene was carried by a bacteriophage (Uchida, Gill & Pappenhcimer, 1971).

A search for nasopharyngeal carriers of Streptococcus pneumoniae was conducted in 573 children hospitalized in Durban, South Africa. Study subjects were divided into two groups, comprising 305 new admissions and 268 patients who had been hospitalized for more than 24 h. Of the 573 children 178(31%) yielded pneumococci on nasopharyngeal culture; 99 (32%) and 79 (29%) children in the new admission and in-patient categories respectively. Twenty-one (12%) pneumococci were resistant to penicillin, including 11 strains that were resistant to more than one antibiotic. Resistant pneumoeoeei belonged exclusively to serotypes 6 and 19 (Danish nomenclature), which were also the commonest serotypes among penicillin-sensitive strains. Factors that correlated with carriage of penicillin-resistant Pneumococci were hospitalization for more than 24 h, young age and recent exposure to beta-lactam antibiotics.

Strains of Neisseria meningitidis isolated from patients with meningitis or septicaemia without meningitis in Scotland during the years 1972–82 have been reviewed together with details of the age, sex, disease and outcome of the patients from whom they were isolated. A total of 1185 strains were isolated, of which 927 were examined at the Meningococcal Reference Laboratory (Scotland): 19·3% were of serogroup A, 63% of group B, 9·6% of group C, 6% of W135 and 1·6% of other groups. Non-groupable strains were rare. Disease was most common in the first years of life but there was a difference in the age distribution of disease due to the different serogroups, the proportion of disease due to group B being smaller in adults than that due to other serogroups. The overall mortality in meningitis was 7·5% and in septicaemia was 20·6%, although there were differences between the rates for the various serogroups. The serogroup distribution differed in disease as opposed to meningococci isolated from carriers although group B strains were predominant in both series. Overall, approximately 15% of strains were resistant to sulphadiazine, the proportion of resistant group A strains being higher than that of other serogroups.

The conversion of non-toxinogenic Corynebacterium diphtheriae to toxinogeny has been reviewed. The biology of converting phage and the relationship of converting phages to nonconverting phages are summarized. The significance of these findings to the natural history and evolution of diphtheria is assessed.

Infants' stools were examined for the presence of Clostridium difficile and its cytotoxin in a study performed over a one-year period on a special care baby unit. Overall, 21% of infants were colonized, but the organism was only recovered in a seven-month period during which its weekly prevalence in the group varied from zero to 44%, with a distinct clustering of colonized infants being observed. Tests for the presence of cytotoxin in the stools and in supernatants of broth that had been inoculated with each isolate were negative. The factors predisposing to colonization were a prolonged stay in the unit, low birth weight, younger gestational age and being nursed in an incubator. The organism was recovered only once from an environmental screen.

An antibiogram, used in conjunction with toxin production, was helpful in distinguishing these isolates from a collection obtained from other units in the hospital. We conclude that Cl. difficile was acquired by nosocomial spread although we did not establish the precise mechanism involved.

The detection of para-cresol by gas–liquid chromatography was found to be specific but insufficiently sensitive as a screening test for the organism's presence in the stools. It could only be demonstrated in infants whose birth-weights were less than 2500 g, and no association was observed between the type of feed and para-cresol presence in stools.

Four hundred and seven clinical isolates of Escherichia coli were examined for the presence of plasmids. These isolates comprised 189 which were collected irrespective of antimicrobial resistance (VP) and 218 which were collected on the basis of high-level trimethoprim resistance (TPR). The VP isolates were divided into drug sensitive (VPS) and drug-resistant (VPR) subpopulations.

Plasmids were detected in 88% of VP isolates (81% of VPS and 94% of VPR) and 98% of TPR isolates. The distribution of plasmids in both groups and subpopulations was very similar. However, there were small but statistically significant differences between the plasmid distributions. These showed that more isolates in the resistant groups harboured plasmids than in the sensitive subpopulation (VPS) and that the number of plasmids carried by resistant isolates was greater. Multiple drug resistance was significantly more common among TPR isolates than the VPR subpopulation and this was paralleled by increased numbers of plasmids.

Fifty-eight per cent of VPR and 57% of TPR isolates transferred antimicrobial resistance and plasmids to E. coli K12. Of the R+ isolates, 60% carried small plasmids (MW < 20Md) and 52% of these co-transferred with R-plasmids. These results are discussed.

Neomycin and polymyxin B, used during selective decontamination of the gastrointestinal tract, were studied for their effect on the human faecal flora in vitro. The selective effect was found to be associated with a relative insusceptibility of the obligate anaerobic flora as compared with the facultatively anaerobic Gram-negative rods (Escherichia coli). Both neomycin and polymyxin B were bound by human faeces, in contrast to ampicillin. The results may explain the selective effect of neomycin and polymyxin B on the human flora in vivo.

A method using an ammonia electrode is being developed for investigating the deamination of amino acids and amides by bacteria. Application of this method to Campylobacter jejuni and C. coli has led to the demonstration of d-asparaginase activity in some strains. This has allowed the subdivision of both species into d-asparaginase-positive and -negative biotypes. Even though the method is in the developmental stage, it was found to be generally reproducible and easy to perform. Areas for further improving the procedure have been identified. The ammonia electrode offers the theoretical possibility of investigating the breakdown of any amino acid by bacteria. It thus opens up a new and practical approach for separating species and strains, particularly in those bacterial groups that are difficult to subdivide by conventional means.

The incidence of diphtheria has declined in North America during the last fifty years until it is now an uncommon disease. This general pattern is similar to that seen in other developed countries with well-organized immunization programmes, but certain noteworthy characteristics have been observed in recent years: foci of infection lingered in two population groups of low socio-economic status, in both of which the skin has been an important reservoir. In central areas of certain cities, endemic diphtheria, chiefly cutaneous, has occurred amongst indigent adult males living in unhygienic conditions; and in the native Indian population of Northern Canada diphtheria infection has been endemic in infants and children, many of the infections being of the skin or ear and toxic disease being uncommon. During the last few years, diphtheria outbreaks have not been reported in urban areas and possibly endemicity is now restricted to northern native populations. The number of infections detected in these northern endemic areas is steadily decreasing.

Solid media were compared for their ability to recover salmonellae from seagull faecal material after pro-enrichment in buffered peptone water and enrichment in Rappaport's broth. Of the 847 specimens examined 96 were found to be positive for salmonellae. Use of Brilliant Green agar containing sulphamandelate supplement resulted in the detection of salmonellae from each of the 96 samples found to be positive and was the most efficient medium tested. Brilliant Green agar lacking the supplement was the least effective medium, salmonellae being isolated from only 80 samples using this medium.

All of the media tested were shown to support the growth of a wide range of salmonella serotypes, although Salmonella typhi and S. dublin did not form colonies on those media which contained Brilliant Green. Hynes' modification of deoxycholate citrate agar was shown to be considerably less inhibitory to salmonellae after ageing for four days. Ageing of other media had no significant affect on their ability to support the growth of salmonellae.

The results of a twelve-year study of Coxsackie B virus (CBV) infections in patients with a variety of acute and chronic illnesses are reported. CBVs were isolated from only 123 patients most of whom were children with respiratory illness. Virus diagnosis in adults was based mainly on the detection of significant rising or static high neutralizing antibody titrcs. Between 1972 and 1979 most investigations centred on patients with suspected viral heart disease, 12% of whom were found to have diagnostically significant CBV titres. In studies on patients with definite myo-pericarditis the number positive increased to 33%. In 1980 clinical interest switched to the possible role of CBV in myalgic encephalomyelitis (ME), an illness of diverse symptomatology. Investigation of suspected cases of ME in 1983 showed that 16% were serologically positive compared to 4% of normal adults in the West of Scotland. In patients with well-documented ME this figure rose to 41%.

The demand by clinicians for CBV neutralizing antibody tests has increased over the past twelve years and continues to escalate annually, especially in patients with chronic relapsing illness.

A letter of inquiry was sent to 21 countries in Europe to ascertain their experience of diphtheria during the last 20 years. An analysis of the 15 replies showed that all relied on childhood vaccination and that this had reduced the annual incidence of the disease to a very low level. There was mention of three epidemics during the last ten years, and three countries identified several cases of skin diphtheria, mostly in patients who had contracted infection abroad.

A comparison of neutralizing and immunofluorescent (IF) IgG antibody tests in 18 sera from 10 cases of hand, foot and mouth disease (HFMD) showed a variety of responses but all sera taken more than one week after infection had both neutralizing and IF IgG antibodies.

A survey of IF IgG antibody in 80 paediatric and 80 adult non-HFMD case sera gave antibody detection rates of 47·5% and 11·3% respectively. This difference could be attributed to a decline in IF IgG antibody with time after infection. Three point nine per cent of 2G sera from possible adult carditis cases had IF antibody suggesting that coxsackie A16 virus was not a common cause of adult carditis. Forty-eight point three per cent of 29 sera from cases of spontaneous abortion had detectable IF antibody, a rate similar to the paediatric sera and significantly greater than that in adult male (7·9%) and other adult female (13%) sera tested. This interesting observation requires further study.

Chickens were readily infected with salmonella organisms when fed diets containing unsterilized bone-meal or provided with drinking water containing a suspension of natural salmonella infected chicken faeces. When fed diets containing avoparcin at concentrations of 10 or 100 mg/kg chickens infected in these ways excreted larger numbers of salmonellas for longer periods than did chickens fed a nonmedicated diet.

Stability of aminoglycoside resistance has been investigated in 20 strains of Staphylococcus aureus resistant to gentamicin (16 strains were also resistant to methicillin). In view of previous reports that incubation at elevated temperatures can hasten the loss of unstable antibiotic resistance, we passaged strains daily in a liquid medium for 24 days at 43 °C. The nine strains which were resistant to neomycin kept their aminoglycoside resistance virtually intact, whereas most of the other 11 strains (sensitive to neomycin) lost almost all their resistance to gentamicin and kanamycin after 5 days. It thus appears that the stability of aminoglycoside resistances in Staph. aureus is closely linked to the resistance of the strains to neomycin. This finding has important possible consequences in terms of the advisability of the clinical usage of preparations containing neomycin or framycetin for topical application and bowel sterilization.

The Rappaport–Vassiliadis enrichment medium (RV medium)in 10 ml quantities (RV/43 °C, 10 ml) inoculated with 0·1 ml of pre-enrichment medium (P medium) was found more efficient in the isolation of salmonellae from 409 pre-enriched samples (mainly meat products), than the original Rappaport medium incubated at 43 °C (R/43 °C) and the RV medium in 5 ml quantities (RV/43 °C, 5 ml) inoculated with 0·01 ml of P medium (P < 0·001, in both instances). Therefore, the inoculum from pre-enriched foods should not be less than 0·l ml in 10 ml of RV medium.

The RV/43°, 10 ml was also better (P < 0·01) in detecting samples containing salmonellas than the original Rappaport medium incubated at 37 °C (R/37 °C, 10 ml) and the modification R25 of R medium incubated at 37 °C. The R25 modification was used in 10 ml quantities (R25/37 °C, 10 ml) inoculated with 0·1 ml of P medium and in 5 ml quantities (R25/37°, 5 ml) inoculated with 0·01 ml of P medium. The last two R25 procedures were of the same efficiency in isolating salmonellas from meat products.

Compared with a similar survey conducted ten years previously, a survey conducted in 1982, eleven years after the implementation of legislation forbidding the routine use of feeds containing ‘therapeutic’ antibiotics, revealed a decreased incidence of resistance to tetracyclines, furazolidone and sulphonamides in Escherichia coli strains causing generalized infections in chickens in the UK; the decrease was particularly marked in the case of tetracycline resistance, 17·9% of strains in 1982 being resistant to this antibiotic compared with 31·2% in 1972.

Giving furazolidone to groups of chickens inoculated intramuscularly with O2:K1 strains of E. coli of differing degrees of furazolidone sensitivity indicated that great care is required in the performance and interpretation of laboratory tests for sensitivity to this antibiotic. Infections caused by strains that required as little as 1·25 μg/ml of furazolidone to inhibit their multiplication in laboratory tests responded poorly to furazolidone treatment; those that were inhibited by less responded well, better than to treatment with tetrac3rcline, chloramphenicol. ampicillin or trimethoprim.