The FH strain of Mycoplasma pneumoniae was studied in experimentally infected cultures of lung diploid fibroblasts. The multiplicity of infection was found to have a profound influence on the distribution of the cell-associated and extra-cellular mycoplasmas. At a high multiplicity there was very little difference between the ratio of cell-associated and extracellular mycoplasmas. In contrast, with a low multiplicity the cell-associated mycoplasmas predominated and with further reductions of the inoculum only the cell-associated mycoplasmas could be detected. The significance of these findings is discussed. It is suggested that caution has to be exercised in the determination of the potency of antibiotics against mycoplasma by methods employing acellular media alone, and it is desirable to utilize also appropriate cell culture models. A possible approach to designing such models is provided by this study.

We express our appreciation to the Tissue Culture Laboratory, Pfizer Limited, Sandwich, for kindly supplying us with cell cultures. We furthermore thank the Board of Directors, Pfizer Limited, for permission to publish this study. The helpful discussions with our colleagues Drs D. Jackson and G. M. Williamson in preparing the manuscript are acknowledged with thanks.

Evidence is presented that outbreaks of myxomatosis among domestic rabbits at Newhaven in Sussex were spread through the agency of Anopheles atroparvus. The habits of this insect are discussed in relation to its possible importance as a vector of myxomatosis.

One question of particular importance in phase III HIV vaccine trials is the choice of efficacy measure (EM) to validly and precisely estimate the true vaccinal efficacy. Traditional EMs, based on hazard rate ratio (HRR) or cumulative incidence ratio (CIR) are time-sensitive to mode of vaccine action and population heterogeneities. Through Monte-Carlo simulation, the performance of HRR and CIR based EMs are examined across different trial designs and vaccine and population characteristics. A new EM based on log-spline hazard regression (HARE) is proposed. Given that vaccinal properties (mode of action, time-lag, waning) are unknown a priori, appropriate selection of EM is problematic, and HRR and CIR can be unreliable to estimate the true maximum efficacy of candidate products. Non-random sexual mixing can exacerbate biases in HRR and CIR. HARE can offer valid estimation across different modes of vaccine action and in presence of frailty effects, contrary to its traditional counterparts. Our simulation studies highlight the weaknesses of widely used EMs while offering guidelines for trial design and suggesting new avenues for statistical analysis.

The Group I paracolon bacilli formed biochemically a stable group. They fermented glucose, maltose, mannite, and dulcite, but not saccharose. Most of them could be distinguished from Salmonella organisms by the late fermentation of lactose or the production of indole. Many resembled the Newcastle bacillus in being late-dulcite fermenters. Serologically 75% of the strains were identical, each containing the A antigen. Some formed a separate group containing the A antigen, and Bact. alkalescens antigen and the C antigen of some Group III strains. The A strains are probably identical with those of Dudgeon & Pulvertaft (1927), but their strains were described as being motile. All Group I strains had minor agglutinins in common with the dysentery bacilli, particularly when freshly isolated. Most of Dudgeon's strains were isolated from cases of urinary infection, but in the present investigation almost all were isolated from the discharges of infants with diarrhoea and enteritis. This organism may be regarded as pathogenic or facultatively so, and deserves a name. I suggest it would be appropriate to attach to it the name of Dudgeon, who was the first to call attention to it.

Biochemically Group III bacilli resembled Group I strains but differed in fermenting saccharose. Some were motile. The metabolic and biochemical properties examined were stable. Serologically many (40%) possessed the A antigen, but also possessed a type-specific antigen, E. Others (37%) possessed both C and D antigens, usually C but sometimes D was dominant. These strains are related to the dysentery bacilli by the possession of common, minor antigens. A group of serologically heterogeneous strains remained (23%), generally unrelated to the dysentery bacilli.

Most Group II bacilli were stable biochemically, but some were not. Many strains of Group IV were unstable. Serologically, Groups II and IV were mostly heterogeneous, although 24% were included in the A, B, C, D, E pattern. Together they formed but a minority of all the paracolon bacilli.

Further serological investigation is required to discover new antigens and to link up the paracolon bacilli isolated from various sources.

This work was carried out under a whole-time grant from the Medical Research Council of Ireland to whom I am indebted.

I wish to record my very best thanks to my director, Prof. R. A. Q. O'Meara, for his continuous interest and invaluable advice at all times and without whose aid this research would not have been possible. My gratitude and thanks are due to my colleague, Dr J. St L. O'Dea, for his unfailing co-operation, particularly in obtaining all the specimens so quickly, in assisting at the post-mortems, and for many other services too numerous to mention.

Thanks are also due to the authorities, doctors and nurses of St Ultan's Hospital, Temple Street Hospital, St Kevin's Hospital, Clonskeagh Fever Hospital, Cork Street Hospital, and the Child Welfare Clinics in Dublin, particularly to Dr F. N. Elcock and Dr T. Murphy for their support and co-operation; to the ‘Diarrhoea and Enteritis’ Committee of the Department of Local Government and Public Health for their supervision of the research; and to the staff of the Department of Bacteriology, Trinity College, Dublin, where the research was carried out, for the help and facilities given.

I would like to thank all those general practitioners in Dublin who co-operated by the early notification of cases and in other ways. Finally, I wish to record my appreciation to the Statistics Branch, Department of Industry and Commerce, for their interest and kindness in furnishing a valuable report.

The prevalence of antibody to hepatitis A virus (HAV) in a group of socially and economically disadvantaged Spanish gypsy children was compared to that of a group of non-gypsy middle-class children. The study included 438 children, 73 gypsies (38 girls and 35 boys, mean age 8·5 years, age range 2–16 years) and 365 non-gypsy controls, randomly selected by age. The presence of anti-HAV was investigated using ELISA.

Among the gypsy children, 82% had antibodies to HAV compared with 9·3% of the children in the control group. The unfavourable living conditions of the gypsy population (e.g. homes with poor sanitary conditions, overcrowding) may explain the high prevalence of HAV infection. These findings underline the need for specific action which targets disadvantaged populations.

Vibrio parahaemolyticus was observed to overwinter in sediments and to be present in considerable numbers in sediments and Clithon retropictus (gastropod mollusc) during summer months at a brackish-water area along Hashizu Creek in Japan. The highest level of the organisms was 97·3 × 106 and 2·3 × 107/100 g in sediments and C. retropictus respectively.

Production of Kanagawa haemolysin was detected in approximately 12% and 20% of strains isolated from sediments and C. retropictus respectively at two stations in Hashizu Creek but were not detected at the other three stations. Two haemolysin-producing strains were isolated from water samples but none were isolated from Corbicula japonica (bivalve molluse). These findings suggest that haemolysin producers are preserved principally in sediments and some shellfish in the brackish-water areas with restricted salinity conditions.

This study examines a series of phenotypic variants of Staphylococcus epidermidis that were generated from a pair of parent variants, isolated from valvular tissue of a patient with prosthetic valve endocarditis. The variants were initially classified by examining their colonial morphology on Congo red agar. In addition to differences in Congo red binding and colonial morphology, they differed in the expression of several surface components and enzymes. Despite these phenotypic differences, all variants had the same restriction endonuclease profile of plasmid DNA. Examination of a collection of clinical isolates demonstrated that phenotypic variation is a common property of S. epidermidis. The ability to express different combinations of surface components and enzymes could contribute to the virulence of S. epidermidis strains by enabling these organisms to colonize a range of diverse environments.

1. The injection of mice with botulinum spores, freed from all traces of superficial toxin, can cause death but only if a very large number is given. This number was found in the case of a highly toxic strain to be of the order of 20 million spores given intramuscularly. This dose was fatal in the absence of spore germination.

2. In human botulism it is concluded that the spores of Clostridium botulinum persent in spoiled foodstuffs are not of importance compared with the toxin produced by the initial growth of the contaminating organisms.

3. Toxin could be demonstrated in the cytoplasm of botulinum spores when these were disintegreted by mechanical means. This is of theoretical interest as the toxin within the spores is more heat-stable than the extracellular form.

4. A local anaerobic myositis could be produced in mice by the intramuscular injection of spores plus 2·5% CaCl2. The number of viable spores in the LD50 was of the order of 50,000.

5. Calcium chloride solution in the commonly used strength of 2·5% was shown regularly to cause a drop in the number of botulinum spores in a given suspersion of some 40% and a parallel loss of viability of about 60%.

Salmonella javiana, a serotype rarely isolated in Australia, has been recovered from the faeces of a 14-month-old infant with symptoms of enteritis.

The child had been closely associated with a marsupial species, the quokka, during a vacation on Rottnest Island in Western Australia, and S. javiana was isolated from faecal pellets from adult quokkas, and also from a snake collected on the island.

Sampling revealed a high incidence of Salmonella infection in the quokkas. In all, 62 out of 87 animals (71%) were found to be infected, and 17 Salmonella and 3 Arizona serotypes were identified from 100 isolations comprising 92 salmonellas and 8 arizonas. Multiple infections were frequently detected and up to four serotypes were recovered from individual animals. S. javiana was isolated from four quokkas.

A close parallel was observed between the serotypes isolated from quokkas and sea-gulls on the island, and abattoir effluents, lake waters, bird droppings and reptiles sampled on the adjacent mainland.

The epidemiological significance of Salmonella and Arizona infections in the quokka population and their possible association with the seasonal decline in condition and numbers of animals on Rottnest Island is discussed.

HIV-positive persons and the elderly have increased risk for influenza-related complications, including pneumonia. Using claims data for pneumonia and influenza (P&I) hospitalization in the USA, we described the temporo-demographic trends and in-patient case-fatality in persons aged ⩾65 years by HIV status. Our results showed a near doubling in the fraction of P&I admissions representing HIV-positive persons between 1991 and 2004 [relative risk (RR) 1·95, 95% confidence interval (CI) 1·80–2·13]. HIV-positive adults were younger (70·3 vs. 79·9 years, P<0·001), and had higher case-fatality (18·0% vs. 12·6%, P<0·001). Adjusting for other variables, case-fatality decreased by 5·8% in HIV-positive persons with the availability of highly active antiretroviral therapy (P=0·032). However, HIV-positive seniors were still 51% more likely to die during hospitalization than HIV-negative persons in 2004 (OR 1·51, 95% CI 1·23–1·85). HIV-infected persons represent a growing fraction of the elderly population hospitalized with P&I. Additional measures are needed to reduce case-fatality associated with P&I in this population.

The overall incidence of spinal tuberculosis (TB) appears to be stable or declining in most European countries, but with an increasing proportion of cases in the foreign-born populations. We performed a retrospective observational study (1993–2014), including all cases of spinal TB diagnosed at a Barcelona hospital to assess the epidemiological changes. Fifty-four episodes (48·1% males, median age 52 years) of spinal TB were diagnosed. The percentage of foreign-born residents with spinal TB increased from 14% to 45·2% in the last 10 years (P = 0·017). Positive Mycobacterium tuberculosis testing in vertebral specimens was 88·2% (15/17) for GeneXpert MTB/RIF. Compared with natives, foreign-born patients were younger (P < 0·01) and required surgery more often (P = 0·003) because of higher percentages of paravertebral abscess (P = 0·038), cord compression (P = 0·05), and persistent neurological sequelae (P = 0·05). In our setting, one-third of spinal TB cases occurred in non-native residents. Compared with natives, foreign-born patients were younger and had greater severity of the disease. The GeneXpert MTB/RIF test may be of value for diagnosing spinal TB.

1. The use of sodium glutamate as a medium for freeze-drying Lact. bifidus significantly enhanced the stability of the dried product, especially the heat stability.

2. The optimal concentration of sodium glutamate, as a drying medium, was found to depend on the bacilliary concentration; the higher the concentration of the bacilliary suspension used the higher was found to be the optimal concentration of the sodium glutamate.

3. It was possible to classify various drying media according to the degree of sublimation of the product during the process of freeze-drying. Two types were observed; in the first, which included sodium glutamate and glucose, the sublimation rate diminished with the increasing concentration of the medium, whereas in the second group, which included polyvinyl pyrrolidon K 90 (PVP), soluble starch and dextran, no such diminution was observed when the concentration of the medium was increased.

4. By the combination of sodium glutamate or glucose with a medium belonging to the second group sublimation was found to be promoted.

5. The stabifity-conferring effect of sodium glutamate on dried Lact. bifidus was markedly enhanced when the glutamate was combined with a drying medium belonging to the second group. This effect is attributed to a desiccation-promoting property of the latter medium.

6. Lact. bifidus as a freeze-dried preparation showed a somewhat better survival rate when sealed in air than when sealed in vacuo. In the case of other anaerobic organisms tested there was no significant difference in the survival rates under the two methods of storage.

Treatment of serum with the insoluble polysaccharide residue of yeast cells (zymosan) has been shown (a) to decrease the bactericidal power of serum for certain bacteria; (b) to remove from some sera a factor essential to the interaction of zymosan with the third component of complement. The adsorbed protein (properdin) was eluted from zymosan and found to contain α2, β and some γ globulins. It was shown to restore partially the normal characteristics to treated serum (RP).

Properdin levels have been estimated in the sera of eighteen burned patients and in twelve normal subjects. There was evidence of a reduced level in the patients' sera. The limitations of the assay method are discussed.

Bactericidal activity of normal serum containing properdin was tested against nineteen Gram-negative bacilli isolated from burns. Ps. pyocyanea, Proteus and Klebsiella, which are commonly found in burns, were with one exception resistant or slightly sensitive to the bactericidal action of this serum. Bact. coli, which is uncommon in burns, was usually highly sensitive.

From our preliminary studies reported here it would seem that the properdin system cannot be expected to kill the flora in established infections of burns, and properdin is therefore unlikely to prove useful as a therapeutic agent. However, it probably has an important role as one of the defence mechanisms of uninfected tissues.

We wish to thank Dr Derrick Rowley and Dr A. C. Wardlaw for helpful discussions, and Dr W. Weiner for his advice and co-operation. We are grateful to Miss Stella Baar, F.R.I.C., for N and P analyses.

Factors affecting the growth of Streptococcus faecalis on glucose-yeast extract-sodium azide agar have been studied. Both the high temperature of incubation used (45° C.) and the presence of azide reduced the proportion of cells able to form colonies, the inhibitory action being much more marked with cultures which had become attenuated, either through age or through prolonged immersion in water, than with comparatively young and vigorous cultures. This inhibitory action was found to be largely overcome if the inoculum was subjected to a preliminary period of ‘resuscitation’, by incubating it with double-strength glucose broth before adding the azide-agar portion of the medium and allowing the mixture to set.

Neutral red was so inhibitory to some strains of Str. faecalis that it could not be included in the medium. Phosphate, as the potassium salt at a concentration of 0.7%, if autoclaved with the remaining constituents of the medium, exerted a depressing effect on the counts. Added separately it showed no inhibitory action.

The spinning-bottle technique (Allen et al. 1952) was adapted for Str. faecalis. When used for samples containing a mixed flora the method, described in the Appendix, permitted the growth only of Str. faecalis.

This paper is published by permission of the Department of Scientific and Industrial Research.

The degree of seroprotection against diphtheria in Poland was evaluated by determination of IgG antibodies to Corynebacterium diphtheriae toxin (IgG-DTAb). The study population consisted of 4829 healthy subjects aged from 1 day to 85 years from 7 regions of Poland. Serum samples collected between 1996 and 1998 were assayed for IgG-DTAb antibodies using a toxoid enzyme immunoassay. Neutralization of toxin in Vero cells was performed as a reference method with the WHO standard for human diphtheria antitoxin. The study revealed a lack of seroprotection (IgG-DTAb < 0·1 IU/ml) in 23 % of individuals, basic seroprotection (0·1–1·0 IU/ml) in 64 %, and effective seroprotection (> 1·0 IU/ml) in 13 %. The non-protected group consisted of non-vaccinated children below 2 months of age (10 %), individuals between 2 months and 18 years old (20 %) and greater than 19 years old (70 %). Of the adults, 32 % were seronegative, 63 % had basic seroprotection and only 5 % were fully protected; 43 % of adults between 30 and 64 years, who had not been vaccinated at least during the previous 10 years were not protected against diphtheria. The geometric mean titre (GMT) of IgG-DTAb was 0·25 IU/ml in the total population. Age-related GMTs differed significantly from each other and were higher (0·44 IU/ml) in individuals from 2 months to 18 years old, compared with 0·14 IU/ml and 0·17 IU/ml in children under 2 months and adults, respectively. No significant difference was found in the GMTs of men and women in all age groups. We conclude that the currently used vaccination programme in Poland is highly effective and assures protection against diphtheria in the majority of the population in the 10-year period following the last booster. However, a significant proportion of adults between 30 and 64 years lack protection and this indicates a need for booster immunization for this group.

Duplicate neutralization tests were done on 401 avian and 101 human sera from island residents collected in the Coral Sea and on Australia's Great Barrier Reef against 19 known arboviruses. Antibodies to a potentially harmful flavivirus, Gadget's Gully virus, were equally present (4%) in both avian and human sera. Antibodies to another flavivirus, Murray Valley Encephalitis, and an ungrouped isolate, CSIRO 1499, were also present in both populations with non-significantly different incidences. Antibodies to Upolu, Johnston Atoll, Lake Clarendon, Taggert, Saumarez Reef and CSIRO 264 viruses were restricted to seabirds. Island residents with antibodies to Ross River and Barmah Forest viruses are thought to have been exposed to these viruses on the mainland as antibody to both viruses was absent among seabirds. These results indicate that consideration should be given to tick-associated arboviruses as potential public health hazards on islands where both seabird and human activities interact.

The characters by which the “R” variant of a given bacterial type is distinguished from the “S” variant are to-day widely known. Most of them are morphological and in most bacterial types it is not difficult to say whether a single colony is smooth or rough; but every bacteriologist is familiar with those borderline colonies, which are apparently smooth, but which later prove to be serologically rough. It sometimes happens that by special stimulation the reversion from an “R” culture into the “S” form succeeds, but that, notwithstanding the smooth appearance of the isolated colonies, the organisms persist in showing some characters which belong to the “R” variant, such as instability in saline (Bruce White, 1926).

The fluorescent antibody technique was used for the identification of specific cytomegalovirus IgM in the sera of twenty-four of 1065 unmarried pregnant women. Seventeen of them were followed to term and five infected infants were identified. Two other infants had CMV IgM in neonatal serum samples but virus excretion was not demonstrated. The congenital infection rate in this study was 5·3 per 1000 births by virus excretion and 7·9 per 1000 if cases with specific IgM are included; from previous studies a rate of 8·8 per 1000 was expected. The reasons for the lack of relationship between specific IgM in the mothers' serum and infected babies is discussed.

Multi-locus sequence typing was performed on 1003 Campylobacter jejuni isolates collected in a 2-year longitudinal study of 15 dairy farms and four sheep farms in Lancashire, UK. There was considerable farm-level variation in occurrence and prevalence of clonal complexes (CC). Clonal complexes ST61, ST21, ST403 and ST45 were most prevalent in cattle while in sheep CC ST42, ST21, ST48 and ST52 were most prevalent. CC ST45, a complex previously shown to be more common in summer months in human cases, was more prevalent in summer in our ruminant samples. Gene flow analysis demonstrated a high level of genetic heterogeneity at the within-farm level. Sequence-type diversity was greater in cattle compared to sheep, in cattle at pasture vs. housed, and in isolates from farms on the Pennines compared to the Southern Fylde. Sequence-type diversity was greatest in isolates belonging to CC ST21, ST45 and ST206.

The efficacy of sodium hypochlorite was assessed against human immunodeficiency virus type 1 suspended in low (8% v/v) or high (80% v/v) concentrations of serum or in a high (80%) concentration of blood. In the presence of 8% serum. 100 p.p.m. available chlorine in the disinfectant test mixture inactivated 3·75 log TCID50 HIV/ml within 30 s. When the test mixture contained 80% serum. 500 p.p.m. available chlorine inactivated more than 4 log TCID50 HIV/ml in 1–2 min. Lower concentrations of available chlorine were unable to inactivate the virus completely. In the presence of 80% blood. 1000 p.p.m. available chlorine in the disinfectant test mixture was unable to inactivate 3·75 log TCID50 HIV/ml. although 2500 p.p.m. available chlorine was able to inactivate at least 1·5 log TCID50 HIV/ml. In all test mixtures, the chlorine rapidly became combined and thus less active. Our results emphasise the importance of cleaning prior to disinfection with sodium hypochlorite since it may prove to be ineffective in the presence of high levels of organic matter. In cases where prior cleaning is impossible, care must be taken to use the higher recommended concentration (a minimum of 10000 p.p.m. available chlorine).