Ethnicity as an independent predictive factor for the results of computed tomography pulmonary angiography and ultrasonography of the lower limbs

BACKGROUND

Asians, Pacific Islanders and Maori have significantly lower rates of venous thromboembolism (VTE) compared to Europeans, but its clinic implication regarding diagnosis and prevention is unclear.

AIMS

To investigate if ethnicity affects the yield of computed tomography pulmonary angiography (CTPA) and ultrasonography of the lower limbs.

METHODS

Data previously collected for 523 patients from another study were used to analyse the effect of ethnicity on the results of CTPA; 1587 consecutive ultrasonography of lower limbs was retrospectively analysed according to ethnicity. The Wells score was retrospectively calculated to determine the pretest probability of VTE.

RESULTS

The positive rates of CTPA were 23.3% for European patients and 9.3% for non-European patients. The rate ratio was 2.50 (confidence interval [CI] 1.27-4.95). European patients were 2.5 times more likely to have a positive scan result than non-Europeans, given same pretest probability. There was a larger difference among patients with low and moderate pretest probability with a rate ratio of 4.27 (CI 1.62-11.3). The positive rates of ultrasound scans (USS) among European patients were 16.6 and 9.0% for non-European patients. Rate ratio was 1.85 (CI 1.27-4.95). The difference was also more significant amongst patients with low and moderate pretest probability. The rate ratio was 2.31 (CI 1.38-3.86) for European patients compared to non-European patients.

CONCLUSION

Given the same pretest probability according to the Wells score, European patients had significantly higher positive rates of CTPA and ultrasonography of the lower limbs than non-European patients. Further prospective studies are required to confirm our findings and establish an appropriate pretest assessment tool for non-European patients.

The costs of falls in the community to the North East Ambulance Service

BACKGROUND

This study set out to quantify the immediate costs to the North East Ambulance Service (NEAS) of attending to fallers.

METHODS

Data from the Newcastle, UK area were collated by NEAS to identify those aged over 65 who had fallen and required an assistance only call or were subsequently transported to an Accident and Emergency (A&E) department. The 2001 census data for the total population served by NEAS in Newcastle were obtained.

RESULTS

The total population of Newcastle over the age of 65 was 41,338. Over 7 months NEAS attended to 1504 falls in Newcastle (at 115 pounds sterling per call out, this equates to 172,960 pounds sterling). The faller was transported to A&E on 1339 occasions, while 165 falls required assistance only (11% of total) (36 falls requiring NEAS assistance per 1000 Newcastle population aged over 65 in 7 months). The total time on site for ambulance crews attending to fallers was 377.1 h (15.7 days in 7 months or 2.25 days per month). As the cost of emergency ambulance time is 123 pounds sterling/h, the total cost was 46,383.30 pounds sterling. Therefore, in Newcastle, attending to fallers in the community costs NEAS 376,018 pounds sterling per year (145.83 pounds sterling per fall or 9.10 pounds sterlingper person over the age of 65 per year).

CONCLUSION

NEAS attend to a significant number of older people who fall in the community. In Newcastle alone the cost of this service equates to over 2 days of emergency ambulance crew time per month. Studies are needed to determine whether responding to falls in the community differently would be cost effective.

Elevated procalcitonin as a diagnostic marker in meningococcal disease

Patients with meningococcal disease who seek medical attention can create a diagnostic dilemma for clinicians due to the nonspecific nature of the disease's presentation. This study assesses the diagnostic accuracy of procalcitonin levels in the setting of meningococcal disease. Two emergency department cohorts (A and B) were studied between 2002 and 2005, during the current epidemic of serogroup B meningococcal disease in New Zealand. Cohort A consisted of 171 patients, all with confirmed meningococcal disease (84 children, 87 adults). Cohort B consisted of a large (n=1,524) consecutively recruited population of febrile patients who presented to the emergency department, 28 of whom had confirmed meningococcal disease. Within the meningococcal disease cohort (cohort A), the geometric mean procalcitonin level was 9.9 ng/ml, with levels being higher in children than in adults (21.6 vs. 4.6 ng/ml, p=0.01). The overall sensitivity of elevated procalcitonin, using a cutoff of 2.0 ng/ml in children and 0.5 ng/ml in adults, was 0.93 (95%CI: 0.88-0.96). Despite the higher cutoff level for paediatric patients, a trend towards greater sensitivity existed in children (0.96 vs. 0.90; p=0.08). Elevated procalcitonin was correlated with whole blood meningococcal load (r=0.50) and Glasgow Meningococcal Sepsis Prognostic Score (r=0.40). Within the cohort of patients who were febrile on presentation (cohort B), the specificity of elevated procalcitonin in meningococcal disease was 0.85 (95% CI: 0.83-0.87), the positive and negative likelihood ratios were 6.1 and 0.08, respectively, and the sensitivity of elevated procalcitonin (0.93; 95% CI: 0.76-0.99) was corroborated. Measurement of procalcitonin is a useful tool in patients with nonspecific febrile illnesses when the possibility of meningococcal disease is present. The diagnostic accuracy surpasses that of current early laboratory markers, allowing results to be used to guide decisions about patient management.

The mumps virus neurovirulence safety test in Rhesus monkeys: a comparison of mumps virus strains

Wild type mumps viruses are highly neurotropic and a frequent cause of aseptic meningitis in unvaccinated humans. To test whether attenuated mumps viruses used in the manufacture of mumps vaccines have neurovirulent properties, a monkey neurovirulence safety test (MNVT) is performed. However, results with several mumps virus MNVTs have raised questions as to whether the test can reliably discriminate neurovirulent from nonneurovirulent mumps virus strains. Here, various mumps virus strains representing a wide range of neuropathogenicity were tested in a standardized MNVT. A trend of higher neurovirulence scores was observed in monkeys inoculated with wild type mumps virus versus vaccine strains, although differences were not statistically significant. Results indicated the need for further examination and refinement of the MNVT or for development of alternative MNVTs.

Double-blind placebo-controlled study of concurrent administration of albendazole and praziquantel in schoolchildren with schistosomiasis and geohelminths

A double-blind placebo-controlled study of the concurrent administration of albendazole and praziquantel was conducted in>1500 children with high prevalences of geohelminths and schistosomiasis. The study sites were in China and the Philippines, including 2 strains of Schistosoma japonicum, and 2 different regions of Kenya, 1 each with endemic Schistosoma mansoni or Schistosoma haematobium. Neither medication affected the cure rate of the other. There was no difference between the side effect rate from albendazole or the double placebo. Praziquantel-treated children had more nausea, abdominal pain, and headache but these side effects were statistically more common in children with schistosomiasis, suggesting a strong influence of dying parasites. The subjects were followed for 6 months for changes in infection status, growth parameters, hemoglobin, and schistosomiasis morbidity. In all 4 sites, a significant 6-month increase in serum hemoglobin was observed in children who received praziquantel, strongly supporting population-based mass treatment.

Practising dermatology via telemedicine

AIM

An interactive telemedicine service has been established between Taumarunui Hospital and the Department of Dermatology at Waikato Hospital. The first one hundred dermatological consultations were reviewed to see if the consultations were satisfactory for medical staff and patients.

METHODS

A proprietary video conferencing system communicating via the Integrated Systems Digital Network was used to conduct dermatological consultations. Data were collected regarding waiting time, diagnosis and follow-up arrangements. Each patient was asked to complete a questionnaire after the consultation.

RESULTS

Of these consultations, 83 were newly referred patients and the rest were follow-ups. The median waiting time for a new patient was 63 days. A variety of skin lesions (in 40 patients), inflammatory eruptions (31) and infections (13) were diagnosed and managed. Sixteen patients had to be seen at the base hospital for surgical treatment (7), face-to-face diagnosis (3), patch testing (3), a second opinion (2), or for personal reasons (1). The others were followed up locally. Savings in time and cost to patients were noted particularly.

CONCLUSION

Only about 20% of consultations with new patients resulted in a further face-to-face appointment. The majority of patients found the telelink acceptable. The data supported the continuation and possible expansion of the dermatology telemedicine service. However, improved image quality is desirable.

Biology of malarial liver stages: implications for vaccine design

The molecular events controlling sporozoite invasion and exo-erythrocytic (EE) development within hepatocytes are largely not understood, and EE parasites are probably better defined immunologically than biologically. The observation that the Plasmodium falciparum sporozoite antigen TRAP (thrombospondin-related anonymous protein) contains multiple adhesive domains that recognize endothelial and hepatocyte receptors indicates that, like leucocyte passage across capillaries, sporozoite invasion probably involves a co-ordinated interaction between sporozoite and hepatic molecules. The parallel with leucocyte extravasation is strengthened by the finding that TRAP contains a functional, integrin-like, I domain. EE parasites are an important target of immunity elicited by irradiated sporozoites, and much current effort is focused on developing malaria vaccines targeting EE parasites. Only one EE-specific antigen, liver-stage antigen 1 (LSA-1), is known to be expressed during EE development and may contribute to protective immunity elicited by irradiated P. falciparum sporozoites. In a study in Papua New Guinea, resistance to P. falciparum infection correlated with CD8+ T-cell interferon-gamma responses to an LSA-1 epitope that contains an HLA A11-restricted sequence. Since A11 is > 40% frequent in this population it is reasonable to suggest that, as with B53 responses to LSA-1 in The Gambia, P. falciparum has driven genetic selection of certain HLA haplotypes, as proposed by Haldane nearly 50 years ago. LSA-1 is thus an important vaccine candidate, and is being expressed in bacterial and phage vectors.

On the role of the World Health Organization in the development of Sabin vaccines

The World Health Organization has played a major part in the development, surveillance and distribution of attenuated poliovirus vaccines. At a time when most of the United States' efforts concerned the introduction of Salk-type vaccines, WHO initiated studies that set standards and permitted the large scale trials of Sabin and other attenuated vaccines. Independent expert review validated studies in countries such as the U.S.S.R. which helped lead to the adoption of Sabin vaccines for worldwide usage. Surveillance by WHO Collaborative Centres established the safety of Sabin vaccines and identified issues of reversion primarily concerning type 3 viruses, initiating studies which have elucidated the molecular mechanism of reversion. Efforts by the Biological Unit of the World Health Organization have ensured worldwide acceptable standards to control the safety and manufacture of vaccines. Revision of neurovirulence test methods has ensured adequate safety testing of vaccine lots, reduced the costs of such studies and the numbers of primates needed, important ethical and conservation issues. Finally, the World Health Organization has played a major part in the worldwide supply of vaccines at affordable prices and has been the repository of, and had the exclusive license, to Sabin vaccines since 1972.

Haemophilus influenzae lobar pneumonia in the father of a child with epiglottitis

We present a case of Haemophilus influenzae lobar pneumonia in the father of a child admitted with acute epiglottitis caused by the same organism. The suggestion that adult, as well as child, contacts for Haemophilus influenzae epiglottitis should be prophylactically treated is discussed.

Haemophilus influenzae lobar pneumonia in the father of a child with epiglottitis

We present a case of Haemophilus influenzae lobar pneumonia in the father of a child admitted with acute epiglottitis caused by the same organism. The suggestion that adult, as well as child, contacts for Haemophilus influenzae epiglottitis should be prophylactically treated is discussed.

Reversion of the attenuated and temperature-sensitive phenotypes of the Sabin type 3 strain of poliovirus in vaccinees

Isolates of type 3 poliovirus from vaccine-recipients were characterized in terms of virulence, sensitivity of growth to high temperatures, and differences in genome structure from the Sabin type 3 vaccine strain. These included point mutations in the region of the genome coding for the structural proteins and in the 5' noncoding region, and the presence of type 1 or type 2 poliovirus genomic sequences resulting from intertypic recombination. Isolates from healthy vaccinees resembled those from vaccine-associated cases of poliomyelitis in all of these properties. Suppression of the temperature-sensitive phenotype was strictly correlated with reversion to virulence in nonrecombinant type 3 strains. Recombinant isolates were more attenuated than expected, even when they had lost all mutations known to attenuate the type 3 vaccine strain.

Papilloedema and respiratory failure

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Nucleotide sequence from neurovirulent and attenuated strains of type 3 poliovirus

As part of an investigation into the molecular basis of attenuation in the Sabin poliovirus vaccines, the genomes of three strains of type 3 poliovirus differing in neurovirulence were cloned in Escherichia coli. The nucleotide sequence of the region of the genome encoding the virion protein 1 (VP1) polypeptide from each of these strains is presented. Very few changes were observed, a finding suggesting that the mutation(s) involved in the attenuation of type 3 poliovirus probably lies elsewhere in the genome. The complete nucleotide sequence of one of the strains, P3/Sabin, has been obtained and is compared with the published sequences of type 1 poliovirus. Between serotypes 1 and 3, there is 77% homology in nucleotide sequence and 90% homology in the amino acid sequence predicted for viral proteins.

Comparison of the complete nucleotide sequences of the genomes of the neurovirulent poliovirus P3/Leon/37 and its attenuated Sabin vaccine derivative P3/Leon 12a1b

As part of a study into the molecular basis of attenuation and reversion to neurovirulence in the Sabin poliovirus vaccines, we have determined the complete nucleotide sequence of a cloned DNA copy of the genome of P3/Leon/37, the neurovirulent progenitor of the type 3 Sabin vaccine strain, P3/Leon 12a1b. Comparison of the sequence with that which we previously obtained for the vaccine strain [Stanway, G., Cann, A. J., Hauptmann, R., Hughes, P., Clarke, L. D., Mountford, R. C., Minor, P. D., Schild, G. C. & Almond, J. W. (1983) Nucleic Acids Res. 11, 5629-5643] indicates that attenuation has been brought about by a maximum of 10 point mutations, at least 5 of which are likely to be of minor significance. Predicted amino acid sequences of all the known virus-encoded proteins show that amino acid substitutions have occurred at only three positions. Two of these are in structural proteins (i.e., Ser----Phe in VP3 and Lys----Arg in VP1), and the third, Thr----Ala, is in the nonstructural protein P2-3b. The distribution and nature of nucleotide and amino acid sequence differences suggest that a single base substitution may be responsible for the attenuated phenotype of the vaccine strain.

Nucleic acid sequence of the region of the genome encoding capsid protein VP1 of neurovirulent and attenuated type 3 polioviruses

Three closely related strains of poliovirus type 3 have been used to study the molecular basis of attenuation in the currently used Sabin vaccine of this serotype. Plaque-purified derivatives of these strains possess closely similar serological and biochemical properties yet differ markedly in neurovirulence for monkeys. Molecular cloning via an RNA . cDNA method has facilitated comparative nucleotide sequencing. Initial efforts have concentrated on the region of the genome encoding VP1. Only minor structural differences between neurovirulent and attenuated type 3 strains were detected, in contrast to the major differences observed between the vaccine strains of poliovirus type 1 and its virulent precursor P1/Mahoney. These observations suggest that the molecular basis of attenuation of type 3 Sabin vaccine virus does not involve the VP1 polypeptide and, therefore, that mutations conferring the attenuated phenotype probably lie elsewhere in the genome.

Location and primary structure of a major antigenic site for poliovirus neutralization

We have determined a major antigenic site for virus neutralization on the capsid protein VP1 of poliovirus type 3. Antigenic mutant viruses selected for resistance to individual monoclonal antibodies had point mutations concentrated in a region 277-294 bases downstream from the start of the region of viral RNA coding for VP1. These findings provide the basis for an improved understanding of the molecular basis of virus neutralization.

Studies in man with a cold-recombinant live influenza B virus vaccine

A cold recombinant live influenza B virus vaccine was tested in man. In comparison to a placebo, reactogenicity attributable to virus infection was slight or moderate. No revertant viruses were shed, and there was no evidence of transmission to the placebo group who were housed in close contact with the vaccinees. Serological responses to initial inoculation were moderate; 60% of vaccinees showing twofold increases in serum hemagglutination inhibition (HAI) titers gave a geometric mean titer (GMT) of 1:13. Three weeks after the first vaccination, both the vaccine and the placebo group were revaccinated with homologous live virus vaccine. The group previously given vaccine was resistant to reinfection as judged from clinical reactions and virus shedding and the GMT increased only slightly to 1:16.3. In contrast, the former placebo group responded; mild symptoms were seen, the majority shed viruses and 50% showed twofold increases in serum HAI titers to a geometric mean titer of 1:17.4.

Studies with some influenza B viruses in cell cultures, hamsters and hamster tracheal organ cultures

Six influenza B virus strains and one recombinant vaccine strain have been compared in cell cultures, hamsters and in hamster tracheal organ cultures. In cell cultures all strains plaque well with or without trypsin. All strains are restricted in growth above 38 degrees C. The cold adapted attenuated virus, influenza B/AA/1/66, and a cold recombinant, RB77, are also restricted in growth above 37 degrees C and thus have a temperature marker. In hamsters influenza B viruses, except strain B/Lee, grow well in lungs and nasal tissues. Small differences were seen between wild type viruses and the cold adapted irus and its recombinants which may serve as additional markers for attenuation.

Studies with a cold-recombinant A/Victoria/3/75 (H3N2) virus. II. Evaluation in adult volunteers

A cold-recombinant influenza A virus, CR 22, derived from A/Ann Arbor/6/60 (H2N2) cold-adapted virus and A/Victoria/3/75 (H3N2) wild-type virus, was tested in adult volunteers. CR 22 induced only low-grade clinical reactions in volunteers who had low titers of serum antibodies. Virus could be reisolated from about one-third of the volunteers, but only at low titers. No revertant viruses were found, and there was no evidence for transmission of virus to unvaccinated volunteers housed in the close contact with the vaccinees. A high proportion of the volunteers seroconverted, and the mean titers of serum antibody after immunization suggest that a high degree of protection is induced by vaccination with liver CR 22 virus.

Studies with a cold-recombinant A/Victoria/3/75 (H3N2) virus. I. biologic, genetic, and biochemical characterization

A cold-recombinant virus CR 22, was derived from an attenuated cold-adapted parent strain. A/Ann Arbor/6/60 (H2N2), and a wild-type parent strain, A/Victoria/3/75 (H3N2). Antigenic analysis showed that CR 22 possesses the hemagglutinin and neruaminidase surface antigens derived from the A/Victoria/3/75 (H3N2) parent. From studies of virus-induced polypeptides using polyacrylamide gel electrophoresis, it was deduced that a polymerase protein, P1, is coded and by an RNA segment derived from the wild-type parent; all other genetic elements are derived from the attenuated parent. The attenuated parent and the recombinant CR 22 both possess temperature-sensitive (ts) lesions, evident by restriction of multiplication in fertile chicken eggs or in Madin-Darby canine kidney cell cultures at greater than or equal to 38 C. Genetic analysis of CR 22 by complementation tests using Hong Kong and Wilson Smith neurotropic ts mutants gave evidence for a ts lesion in the genetic elements coding for complementary RNA.

Studies in man with cold-recombinant influenza virus (H1N1) live vaccines

Two cold-recombinant influenza A (H1N1) viruses were tested in several groups of human volunteers. Only minor clinical symptoms were seen and no febrile reactions occurred. With serologically primed individuals virus shedding was low, but a high proportion showed rises in serum antibody levels after vaccination and mean titres were high. With serologically unprimed volunteers shedding was high, about 75% yielding viruses but only at low titres and for a short duration. No revertant viruses were found and there was no evidence of transmission to potentially susceptible individuals housed in close contact to the vaccinees. Serum antibody responses with unprimed volunteers were, however, low. Only about one half showed increases in serum antibody titres after vaccination and mean titres were low. Nevertheless, challenge with live attenuated virus indicated a high degree of protection based on virological evidence of infection.

The structural and infected cell polypeptides of influenza B virus

Structural and virus-induced infected cell polypeptides of several strains of influenza B virus were examined by high resolution polyacrylamide gel electrophoresis and shown to be directly analogous to those of the influenza A viruses. Eight structural polypeptides, P1, P2, P3, HA1, HA2, NA, NP and M were observed in purified virus and at least two additional polypeptides, HA and NS could be detected in infected MDCK cells. The three P proteins plus NP were shown to be associated with RNA-dependent RNA polymerase activity and HA, HA1, HA2 and NA were shown to be glycosylated. Like the influenza A viruses, migrational differences of some of the infected cell polypeptides could be observed between different B strains. Investigation of a time course of virus replication failed to show any temporal control of protein synthesis in the infected cell.

Growth of some attenuated influenza viruses in hamster tracheal organ cultures

Hamster tracheal organ cultures were infected with different influenza viruses and the metabolic activity measured using a tetrazolium reduction assay. In addition, relative ciliary activity was observed, virus multiplication measured, and histological studies were made. The hamster organ cultures proved relatively simple to set up and were sensitive to infection with influenza viruses; and the tetrazolium reduction was a reliable objective measure of relative tissue damage correlating well with histological and virological findings as well as with visual assessment of ciliary activities.

Growth of some attenuated influenza A viruses in hamsters

The replication of three attenuated influenza viruses in SPF hamsters inoculated by aerosol was investigated. Strains A2-Eng, A2-Victoria, ts-1-[E] A2-Victoria recombinant, and the RIT 4050 strain all multiplied to high titers in hamster lungs and induced both primary and secondary serological responses. Recombinant strain, A/AA/6/60-A2-Vic (CR22) multiplied to lower titers in hamsters. Differences were observed between the infectivity of different strains for hamsters, the wild-type viruses A2-Eng and A2-Vic being the most infective.

Infection of the uterine cervix with Chlamydia trachomatis

For identification of those variables in the history and in the clinical and routine laboratory examination that are most likely to indicate infection of the uterine cervix with Chlamydia trachomatis, 284 women attending a venereal disease clinic were studied, were studied, of whom 58 (20.4%) yielded the organism from the cervix. Women with chlamydial cervical infection showed no distinctive symptoms. Although associations were found between the presence of C. trachomatis and cervical discontinuity, purulent cervical exudate, and inflammatory changes in cervical cytology, these signs were not pathognomonic of chlamydial infection since they were also seen in some women infected with other microorganisms. There was a significant relationship between the presence of antibodies, detected by immunofluorescence, and the recovery of C. trachomatis in cell culture. There were no associations between ethnic group, history of sexually transmitted disease, method of contraception, phase in the menstrual cycle, or numbers of sexual contacts and infection with C. trachomatis.

Simplified serological test for antibodies to Chlamydia trachomatis

Three-hundred sixty sera from unselected patients attending two London venereal disease clinics were examined by a microimmunofluorescence test. Eleven egg-grown serotypes of Chlamydia trachomatis and the so-called "fast" strain SA2(f) were used as antigens. Of the 360 sera tested, 119 (33%) reacted to a titer of 1:16 or above with at least one antigen. Of these positive sera, over 50% cross-reacted with all 12 serotypes, and 95.5% reacted with SA2(f) in addition to other antigenic types. It is suggested that SA2(f) could be used as a single antigen for preliminary screening of a large number of sera for the presence or absence of chlamydial antibody.

The lack of effect of ampicillin plus probenecid given for genital infections with Neisseria gonorrhoeae on associated infections with Chlamydia trachomatis

Forty-six men were successfully treated with a single oral dose of ampicillin (2 g) plus probenecid (1 g) for urethral infections with Neisseria gonorrhoeae. Chlamydia trachomatis was isolated from cultures of cells obtained from 11 of these men both before and after treatment; C. trachomatis was isolated from one man before but not after treatment and from three men after but not before treatment. No isolates were obtained from the remaining 31 men either before or after treatment. Of the 15 patients whose cultures yielded C. trachomatis, 12 developed postgonococcal urethritis; of the 31 patients from whose cultures no isolate was obtained, five developed postgonococcal urethritis. Of 44 women successfully treated with ampicillin plus probenecid for cervical infections with N. gonorrhoeae, 18 had C. trachomatis isolated from the cervix both before and after treatment. C. trachomatis was isolated from five women before but not after treatment and from two women after but not before treatment. No isolates were obtained from the remaining 19 women either before or after treatment. Thus ampicillin plus probencide in the dosage used rarely eliminated C. trachomatis from the genital tract of either men or women. Whereas men with a persisting chlamydial infection will probably develop postgonococcal urethritis and thus receive appropriate treatment, such an infection in women is not likely to be suspected unless attempts are made to isolate C. trachomatis.

Chlamydial infection of the male urethra

Urethral specimens from 477 men were collected with endourethral swabs and examined for Chlamydia trachomatis by cell culture on McCoy cells pretreated with idoxuridine. Of these men, 141 had gonococcal urethritis, 262 non-gonococcal urethritis (NGU), and 74 showed no evidence of urethritis. Of 118 men with heterosexually acquired gonococcal urethritis, thirty (25 per cent.), and of 23 men with homosexually acquired gonococcal urethritis, five (22 per cent.), yielded C. trachomatis from the urethra. Urethral specimens from 240 heterosexual men with NGU were examined, and 118 (49 per cent.) yielded C. trachomatis. Of these 240 men, 140 gave a past history of gonococcal or nongonococcal urethritis and 67 (48 per cent.) of these were positive for C. trachomatis; no past history was given by 100 men, of whom 51 were positive for C. trachomatis. Of the 240 heterosexual men with NGU, 81 had had symptoms for 7 days or more before examination, of whom 48 (59 per cent.) yielded isolates of C. trachomatis, and 145 had had symptoms for less than 7 days, of whom 59 (41 per cent.) yielded isolates. Of fourteen asymptomatic men, three were positive for C. trachomatis. Of 22 homosexual men with NGU, seven (32 per cent.) yielded C. trachomatis. C. trachomatis was recovered from the urethra in three (5 per cent.) of sixty heterosexual men without urethritis, and none of fourteen homosexual men without urethritis yielded C. trachomatis.

Laboratory procedures for the isolation of chlamydia trachomatis from the human genital tract

The technique of isolating Chlamydia trachomatis from the human gential tract by centrifuging clinical specimens on to cell monolayers with subsequent incubation has been improved and simplified. Gentamicin in the media was found to be superior to streptomycin in reducing bacterial contamination of specimens. The infectivity of chlamydial suspensions of laboratory cultured material was significantly reduced by storage at +4 degrees C for more than 48 hours, and by immediate freezing to -70 degrees C. When compared with immediate processing of the specimens, freezing to -70 degrees C was found to reduce the isolation rate of C.trachomatis from men with non-gonococcal urethritis (NGU) by approximately 20%. McCoy cells pretreated with idoxuridine were compared with irradiated McCoy cells for the isolation of C. trachomatis from clinical specimens. There was no significant difference in sensitivity between the two systems, but the former is considerably simpler. The effect of the centrifugal force used for inoculating specimens on to the cell monolayers on the isolation rate of C. trachomatis was studied in groups of men with NGU. Maximal isolation rates were obtained with forces of about 3000 G, which were not significantly raised by further increasing the force used. It is suggested that the isolation of C. trachomatis from the genital tract is now well within the capacity of any laboratory equipped with simple cell culture facilities.

Minocycline in the treatment of nongonococcal urethritis: its effect on Chlamydia trachomatis

The effect of minocycline on nongonococcal urethritis (NGU) was investigated, with particular reference to its action against Chlamydia trachomatis. Preliminary laboratory studies showed that the drug was active against a laboratory chlamydial strain (Lb4f) in vitro. A group of 133 men with first attacks of NGU was then treated with minocycline, 100 mg twice daily for 3 weeks. Isolates of C trachomatis were obtained from 33 of these men before treatment; all of them gave negative results on cell culture after therapy. Of the 133 patients, 119 (90%) had symptoms on their first attendance, but after one week's treatment only 16 of the 133 (12%) and after 3 weeks 6 of the 133 (5%) had symptoms. All 133 men had demonstrable urethritis initially; by the end of the first week of treatment only 43 of the 133 (32%) and by the end of the third week 32 of the 133 (24%) had evidence of urethritis. There were no differences in clinical response between the Chlamydia-positive and Chlamydia-negative groups. A group of 24 female sexual contacts of men with NGU yielded C trachomatis on cell culture. After 3 weeks' therapy with minocycline all these women gave negative results on cell culture. It is concluded that minocycline is a useful addition to existing remedies for NGU. The future structure of treatment trials for NGU is discussed.

Infection with Chlamydia group A in men with urethritis due to Neisseria gonorrhoeae

Men with urethritis due to Neisseria gonorrhoeae were treated with gentamicin, which is inactive against Chlamydia. Urethral specimens were collected before treatment and one and two weeks after treatment and cultured for Chlamydia in irradiated McCoy cells. The overall incidence of chlamydial infection was 15 of 44 (34%). All of 15 Chlamydia-positive men and 11 of 29 Chlamydia-negative men (38%) developed postogonococcal urethritis two weeks after treatment. Pre-treatment sera were examined by a complement fixation test and a simplified indirect fluorescent antibody (FA) test with a yolk sac-cultured antigen, strain SA2)f). Sera from all of 15 Chlamydia-positive men had titers of larger than or equal to 1:16 in the indirect FA test; 13 of 29 Chlamydia-negative men (45%) had positive tests. The complement fixation test was insensitive, detecting chlamydial antibodies in only one of 15 sera from Chlamydia-positive men. These results suggest that Chlamydia may cause many cases of postgonococcal urethritis.

The ribonucleic acid of infectious bronchitis virus

Analysis of the nucleic acid of infectious bronchitis virus by SDS polyacrylamide gel electrophoresis revealed an RNA of molecular weight 9.0 times 10-6 Daltons. The RNA was shown to have a sedimentation coefficient of 50.