Effects of SARS-CoV-2 strain variation on virus neutralisation titres: therapeutic use of convalescent plasma

We compared neutralising antibody titres of convalescent samples collected before and after the emergence of novel strains of SARS-CoV-2, against the wild-type virus (WT), Alpha (B.1.1.7) and Beta (B.1.351) variants. Plasma collected in 2020 before emergence of variants showed reduced titres against the Alpha variants, and both sets of samples demonstrated significantly reduced titres against Beta. Comparison of microneutralisation titres to those obtained with pseudotype and HAT assays showed a good correlation of titres and effects of strain variation, supporting the use of these simpler assays for assessment of convalescent plasma potency against currently circulating and emerging strains of SARS-CoV-2.

Virological Characterization of Critically Ill Patients With COVID-19 in the United Kingdom: Interactions of Viral Load, Antibody Status, and B.1.1.7 Infection

BACKGROUND

Convalescent plasma containing neutralizing antibody to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is under investigation for coronavirus disease 2019 (COVID-19) treatment. We report diverse virological characteristics of UK intensive care patients enrolled in the Immunoglobulin Domain of the REMAP-CAP randomized controlled trial that potentially influence treatment outcomes.

METHODS

SARS-CoV-2 RNA in nasopharyngeal swabs collected pretreatment was quantified by PCR. Antibody status was determined by spike-protein ELISA. B.1.1.7 was differentiated from other SARS-CoV-2 strains using allele-specific probes or restriction site polymorphism (SfcI) targeting D1118H.

RESULTS

Of 1274 subjects, 90% were PCR positive with viral loads 118-1.7 × 1011IU/mL. Median viral loads were 40-fold higher in those IgG seronegative (n = 354; 28%) compared to seropositives (n = 939; 72%). Frequencies of B.1.1.7 increased from <1% in November 2020 to 82% of subjects in January 2021. Seronegative individuals with wild-type SARS-CoV-2 had significantly higher viral loads than seropositives (medians 5.8 × 106 and 2.0 × 105 IU/mL, respectively; P = 2 × 10-15).

CONCLUSIONS

High viral loads in seropositive B.1.1.7-infected subjects and resistance to seroconversion indicate less effective clearance by innate and adaptive immune responses. SARS-CoV-2 strain, viral loads, and antibody status define subgroups for analysis of treatment efficacy.

Comparability of six different immunoassays measuring SARS-CoV-2 antibodies with neutralizing antibody levels in convalescent plasma: From utility to prediction

BACKGROUND

Convalescent plasma (CP) therapy for coronavirus disease (COVID-19) provides virus-neutralizing antibodies that may ameliorate the outcome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. The effectiveness of CP likely depends on its antiviral neutralizing potency and is determined using in vitro neutralizing antibody assays.

STUDY DESIGN AND METHODS

We evaluated abilities of three immunoassays for anti-spike antibodies (EUROimmun, Ortho, Roche), a pseudotype-based neutralization assay, and two assays that quantify ACE2 binding of spike protein (GenScript and hemagglutination test [HAT]-based assay) to predict neutralizing antibody titers in 113 CP donations. Assay outputs were analyzed through linear regression and calculation of sensitivities and specificities by receiver operator characteristic (ROC) analysis.

RESULTS

Median values of plasma samples containing neutralizing antibodies produced conversion factors for assay unitage of ×6.5 (pseudotype), ×19 (GenScript), ×3.4 (HAT assay), ×0.08 (EUROimmun), ×1.64 (Roche), and ×0.10 (Ortho). All selected assays were sufficient in identifying the high titer donations based on ROC analysis; area over curve ranged from 91.7% for HAT and GenScript assay to 95.6% for pseudotype assay. However, their ability to predict the actual neutralizing antibody levels varied substantially as shown by linear regression correlation values (from 0.27 for Ortho to 0.61 for pseudotype assay).

DISCUSSION

Overall, the study data demonstrate that all selected assays were effective in identifying donations with high neutralizing antibody levels and are potentially suitable as surrogate assays for donation selection for CP therapy.

Convalescent plasma or hyperimmune immunoglobulin for people with COVID-19: a living systematic review

BACKGROUND

Convalescent plasma and hyperimmune immunoglobulin may reduce mortality in patients with viral respiratory diseases, and are currently being investigated in trials as potential therapy for coronavirus disease 2019 (COVID-19). A thorough understanding of the current body of evidence regarding the benefits and risks is required.  OBJECTIVES: To continually assess, as more evidence becomes available, whether convalescent plasma or hyperimmune immunoglobulin transfusion is effective and safe in treatment of people with COVID-19.

SEARCH METHODS

We searched the World Health Organization (WHO) COVID-19 Global Research Database, MEDLINE, Embase, Cochrane COVID-19 Study Register, Centers for Disease Control and Prevention COVID-19 Research Article Database and trial registries to identify completed and ongoing studies on 4 June 2020.

SELECTION CRITERIA

We followed standard Cochrane methodology. We included studies evaluating convalescent plasma or hyperimmune immunoglobulin for people with COVID-19, irrespective of study design, disease severity, age, gender or ethnicity. We excluded studies including populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)) and studies evaluating standard immunoglobulin.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess bias in included studies, we used the Cochrane 'Risk of bias' tool for randomised controlled trials (RCTs), the Risk of Bias in Non-randomised Studies - of Interventions (ROBINS-I) tool for controlled non-randomised studies of interventions (NRSIs), and the assessment criteria for observational studies, provided by Cochrane Childhood Cancer for non-controlled NRSIs.  MAIN RESULTS: This is the first living update of our review. We included 20 studies (1 RCT, 3 controlled NRSIs, 16 non-controlled NRSIs) with 5443 participants, of whom 5211 received convalescent plasma, and identified a further 98 ongoing studies evaluating convalescent plasma or hyperimmune immunoglobulin, of which 50 are randomised. We did not identify any completed studies evaluating hyperimmune immunoglobulin. Overall risk of bias of included studies was high, due to study design, type of participants, and other previous or concurrent treatments. Effectiveness of convalescent plasma for people with COVID-19  We included results from four controlled studies (1 RCT (stopped early) with 103 participants, of whom 52 received convalescent plasma; and 3 controlled NRSIs with 236 participants, of whom 55 received convalescent plasma) to assess effectiveness of convalescent plasma. Control groups received standard care at time of treatment without convalescent plasma. All-cause mortality at hospital discharge (1 controlled NRSI, 21 participants) We are very uncertain whether convalescent plasma has any effect on all-cause mortality at hospital discharge (risk ratio (RR) 0.89, 95% confidence interval (CI) 0.61 to 1.31; very low-certainty evidence). Time to death (1 RCT, 103 participants; 1 controlled NRSI, 195 participants) We are very uncertain whether convalescent plasma prolongs time to death (RCT: hazard ratio (HR) 0.74, 95% CI 0.30 to 1.82; controlled NRSI: HR 0.46, 95% CI 0.22 to 0.96; very low-certainty evidence). Improvement of clinical symptoms, assessed by need for respiratory support (1 RCT, 103 participants; 1 controlled NRSI, 195 participants) We are very uncertain whether convalescent plasma has any effect on improvement of clinical symptoms at seven days (RCT: RR 0.98, 95% CI 0.30 to 3.19), 14 days (RCT: RR 1.85, 95% CI 0.91 to 3.77; controlled NRSI: RR 1.08, 95% CI 0.91 to 1.29), and 28 days (RCT: RR 1.20, 95% CI 0.80 to 1.81; very low-certainty evidence). Quality of life No studies reported this outcome.  Safety of convalescent plasma for people with COVID-19 We included results from 1 RCT, 3 controlled NRSIs and 10 non-controlled NRSIs assessing safety of convalescent plasma. Reporting of adverse events and serious adverse events was variable. The controlled studies reported on adverse events and serious adverse events only in participants receiving convalescent plasma. The duration of follow-up varied. Some, but not all, studies included death as a serious adverse event.  Grade 3 or 4 adverse events (13 studies, 201 participants) The studies did not report the grade of adverse events. Thirteen studies (201 participants) reported on adverse events of possible grade 3 or 4 severity. The majority of these adverse events were allergic or respiratory events. We are very uncertain whether or not convalescent plasma therapy affects the risk of moderate to severe adverse events (very low-certainty evidence).  Serious adverse events (14 studies, 5201 participants)  Fourteen studies (5201 participants) reported on serious adverse events. The majority of participants were from one non-controlled NRSI (5000 participants), which reported only on serious adverse events limited to the first four hours after convalescent plasma transfusion. This study included death as a serious adverse event; they reported 15 deaths, four of which they classified as potentially, probably or definitely related to transfusion. Other serious adverse events reported in all studies were predominantly allergic or respiratory in nature, including anaphylaxis, transfusion-associated dyspnoea, and transfusion-related acute lung injury (TRALI). We are very uncertain whether or not convalescent plasma affects the number of serious adverse events.

AUTHORS' CONCLUSIONS

We are very uncertain whether convalescent plasma is beneficial for people admitted to hospital with COVID-19. For safety outcomes we also included non-controlled NRSIs. There was limited information regarding adverse events. Of the controlled studies, none reported on this outcome in the control group. There is only very low-certainty evidence for safety of convalescent plasma for COVID-19.  While major efforts to conduct research on COVID-19 are being made, problems with recruiting the anticipated number of participants into these studies are conceivable. The early termination of the first RCT investigating convalescent plasma, and the multitude of studies registered in the past months illustrate this. It is therefore necessary to critically assess the design of these registered studies, and well-designed studies should be prioritised. Other considerations for these studies are the need to report outcomes for all study arms in the same way, and the importance of maintaining comparability in terms of co-interventions administered in all study arms.  There are 98 ongoing studies evaluating convalescent plasma and hyperimmune immunoglobulin, of which 50 are RCTs. This is the first living update of the review, and we will continue to update this review periodically. These updates may show different results to those reported here.

Convalescent plasma or hyperimmune immunoglobulin for people with COVID-19: a rapid review

BACKGROUND

Convalescent plasma and hyperimmune immunoglobulin may reduce mortality in patients with respiratory virus diseases, and are currently being investigated in trials as a potential therapy for coronavirus disease 2019 (COVID-19). A thorough understanding of the current body of evidence regarding the benefits and risks is required.  OBJECTIVES: To assess whether convalescent plasma or hyperimmune immunoglobulin transfusion is effective and safe in the treatment of people with COVID-19.

SEARCH METHODS

The protocol was pre-published with the Center for Open Science and can be accessed here: osf.io/dwf53  We searched the World Health Organization (WHO) COVID-19 Global Research Database, MEDLINE, Embase, Cochrane COVID-19 Study Register, Centers for Disease Control and Prevention COVID-19 Research Article Database and trials registries to identify ongoing studies and results of completed studies on 23 April 2020 for case-series, cohort, prospectively planned, and randomised controlled trials (RCTs).

SELECTION CRITERIA

We followed standard Cochrane methodology and performed all steps regarding study selection in duplicate by two independent review authors (in contrast to the recommendations of the Cochrane Rapid Reviews Methods Group). We included studies evaluating convalescent plasma or hyperimmune immunoglobulin for people with COVID-19, irrespective of disease severity, age, gender or ethnicity. We excluded studies including populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)) and studies evaluating standard immunoglobulins.

DATA COLLECTION AND ANALYSIS

We followed recommendations of the Cochrane Rapid Reviews Methods Group regarding data extraction and assessment. To assess bias in included studies, we used the assessment criteria tool for observational studies, provided by Cochrane Childhood Cancer. We rated the certainty of evidence using the GRADE approach for the following outcomes: all-cause mortality at hospital discharge, improvement of clinical symptoms (7, 15, and 30 days after transfusion), grade 3 and 4 adverse events, and serious adverse events.  MAIN RESULTS: We included eight studies (seven case-series, one prospectively planned, single-arm intervention study) with 32 participants, and identified a further 48 ongoing studies evaluating convalescent plasma (47 studies) or hyperimmune immunoglobulin (one study), of which 22 are randomised. Overall risk of bias of the eight included studies was high, due to: study design; small number of participants; poor reporting within studies; and varied type of participants with different severities of disease, comorbidities, and types of previous or concurrent treatments, including antivirals, antifungals or antibiotics, corticosteroids, hydroxychloroquine and respiratory support. We rated all outcomes as very low certainty, and we were unable to summarise numerical data in any meaningful way. As we identified case-series studies only, we reported results narratively. Effectiveness of convalescent plasma for people with COVID-19 The following reported outcomes could all be related to the underlying natural history of the disease or other concomitant treatment, rather than convalescent plasma. All-cause mortality at hospital discharge All studies reported mortality. All participants were alive at the end of the reporting period, but not all participants had been discharged from hospital by the end of the study (15 participants discharged, 6 still hospitalised, 11 unclear). Follow-up ranged from 3 days to 37 days post-transfusion. We do not know whether convalescent plasma therapy affects mortality (very low-certainty evidence).  Improvement of clinical symptoms (assessed by respiratory support) Six studies, including 28 participants, reported the level of respiratory support required; most participants required respiratory support at baseline. All studies reported improvement in clinical symptoms in at least some participants. We do not know whether convalescent plasma improves clinical symptoms (very low-certainty evidence). Time to discharge from hospital Six studies reported time to discharge from hospital for at least some participants, which ranged from four to 35 days after convalescent plasma therapy.  Admission on the intensive care unit (ICU) Six studies included patients who were critically ill. At final follow-up the majority of these patients were no longer on the ICU or no longer required mechanical ventilation. Length of stay on the ICU Only one study (1 participant) reported length of stay on the ICU. The individual was discharged from the ICU 11 days after plasma transfusion. Safety of convalescent plasma for people with COVID-19 Grade 3 or 4 adverse events  The studies did not report the grade of adverse events after convalescent plasma transfusion. Two studies reported data relating to participants who had experienced adverse events, that were presumably grade 3 or 4. One case study reported a participant who had moderate fever (38.9 °C). Another study (3 participants) reported a case of severe anaphylactic shock. Four studies reported the absence of moderate or severe adverse events (19 participants). We are very uncertain whether or not convalescent plasma therapy affects the risk of moderate to severe adverse events (very low-certainty evidence). Serious adverse events One study (3 participants) reported one serious adverse event. As described above, this individual had severe anaphylactic shock after receiving convalescent plasma. Six studies reported that no serious adverse events occurred. We are very uncertain whether or not convalescent plasma therapy affects the risk of serious adverse events (very low-certainty evidence).  AUTHORS' CONCLUSIONS: We identified eight studies (seven case-series and one prospectively planned single-arm intervention study) with a total of 32 participants (range 1 to 10). Most studies assessed the risks of the intervention; reporting two adverse events (potentially grade 3 or 4), one of which was a serious adverse event. We are very uncertain whether convalescent plasma is effective for people admitted to hospital with COVID-19 as studies reported results inconsistently, making it difficult to compare results and to draw conclusions. We identified very low-certainty evidence on the effectiveness and safety of convalescent plasma therapy for people with COVID-19; all studies were at high risk of bias and reporting quality was low. No RCTs or controlled non-randomised studies evaluating benefits and harms of convalescent plasma have been completed. There are 47 ongoing studies evaluating convalescent plasma, of which 22 are RCTs, and one trial evaluating hyperimmune immunoglobulin. We will update this review as a living systematic review, based on monthly searches in the above mentioned databases and registries. These updates are likely to show different results to those reported here.

Increased regulatory T cell graft content is associated with improved outcome in haematopoietic stem cell transplantation: a systematic review

Allogeneic haematopoietic stem cell transplant (HSCT) recipients are at increased risk of morbidity and mortality, often due to the development of acute or chronic graft-versus-host disease (GVHD). Low numbers or proportions of regulatory T cells (Tregs) have been reported in patients who develop GVHD. We undertook a systematic review of studies that reported the Treg composition of HSCT grafts in patients with haematological malignancies. Fourteen eligible studies were identified, eight of which stratified patients by Tregs (absolute dose or ratio to CD3+ or CD4+ cells). Meta-analyses showed that high levels of Tregs in the grafts were associated with improved overall survival [hazard ratio (HR) 0·42, 95% confidence interval (CI) 0·23-0·74, P = 0·003, 2 studies], with a significant reduction in non-relapse mortality (HR 0·30, 95% CI 0·14-0·64, P = 0·002, 2 studies) and a reduced risk of acute GVHD (relative risk (RR) 0·59, 95% CI 0·40-0·89, P = 0·01, 6 studies). The consistency of these findings strongly suggests that the Treg composition of HSCT grafts has a powerful effect on the success of allogeneic HSCT. The major challenge is to translate these findings into better selection of allografts and future donors to provide a substantial improvement in allogeneic HSCT outcomes and practice.

A study of the intestinal carriage of antibiotic resistant Staphylococcus aureus by Nigerian children

BACKGROUND

The gastrointestinal tract has been recognized as a major ecological site for Staphylococcus aureus where it can reach neighboring sites and cause mild or serious infections.

OBJECTIVES

To determine the prevalence of intestinal carriage of S. aureus in children aged 3 years and below in Ile-Ife, Nigeria and the antibiotic resistance characteristics of the organisms obtained.

METHODS

The organisms isolated in the course of the study were identified by phenotypic and genotypic methods and screened against 13 antibiotics by conventional methods. A total of 293 subjects were sampled of which 130 were diagnosed with diarrheal at the time of the study while the rest were apparently healthy.

RESULTS

14.0% of the faecal samples yielded S. aureus with the carriage rate among the subjects being found to be highest at about 1 month approximately in subjected ages. Sixty-five percent of the isolates were found to be resistant to more than three different antibiotics with more than 50% being resistant to penicillin, erythromycin and trimethoprim.

CONCLUSIONS

The results of the study indicated that a reservoir of multiply antibiotic resistant S. aureus exists in the gastrointestinal tracts of children living within the study environment.

Quality and bioavailability of tetracycline capsules in a Nigerian semi-urban community

Six batches of tetracycline capsules were purchased from different dispensing points in Ile-Ife, a Nigerian semi-urban town and subjected to weight uniformity tests, microbiological assay and chromatographic determination of degradation products. Four of them were also subjected to dissolution tests and a comparative bioavailability study. A batch of capsules obtained from the local manufacturer of the innovators product was used as the reference standard. From this study, it is apparent that the tetracycline capsules available in this locality are of poor pharmaceutical quality. This has led to poor relative availability and may have made some contribution to the high level of tetracycline resistance in the sample environment.

Identification of the HLA-DM/HLA-DR interface

Human leukocyte antigen (HLA)-DM is a critical participant in antigen presentation that catalyzes the dissociation of the Class II-associated Invariant chain-derived Peptide (CLIP) from the major histocompatibility complex (MHC) Class II molecules. There is competition amongst peptides for access to an MHC Class II groove and it has been hypothesised that DM functions as a 'peptide editor' that catalyzes the replacement of one peptide for another within the groove. It is established that the DM catalyst interacts directly with the MHC Class II but the precise location of the interface is unknown. Here, we combine previously described mutational data with molecular docking and energy minimisation simulations to identify a putative interaction site of >4000A2 which agrees with known point mutational data for both the DR and DM molecule. The docked structure is validated by comparison with experimental data and previously determined properties of protein-protein interfaces. A possible dissociation mechanism is suggested by the presence of an acidic cluster near the N terminus of the bound peptide.

Antimicrobial and antioxidant activities of some Nigerian medicinal plants

Ten Nigerian plants suggested from their ethnomedical uses to possess antimicrobial and antioxidant activities were studied for their anti-microbial and anti-oxidant properties. Antimicrobial activity was tested against Escherichia coli NCTC 10418, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Candida pseudotropicalis and Trichophyton rubrum (clinical isolate). Trichilia heudelotti leaf extract showed both antibacterial and antifungal activities and was the most active against all the strains of bacteria tested. Boerhavia diffusa, Markhamia tomentosa and T. heudelotti leaf extracts inhibited the gram negative bacteria E. coli and P. aeruginosa strains whereas those of M. tomentosa, T. heudelotti and Sphenoceutrum jollyamum root inhibited at least one of the fungi tested. At a concentration of 312 microg/ml, hexane and chloroform fractions of T. heudelotti extract inhibited 6 and 14% of the fifty multi-drug resistant bacteria isolates from clinical infections, respectively. At < or = 5 mg/ml, the CHCl(3) (64%) and aqueous (22%) fractions of T. heudelotti and those of CHCl(3) (34%) and EtOAC (48%) of M. tomentosa gave the highest inhibition that was stronger than their corresponding methanol extracts. The corresponding EC(50) of the extracts on M. acuminata, T. heudelotti, E. senegalensis and M. tomentosa were 4.00, 6.50, 13.33, and 16.50 ig/ml using the TLC staining and 1,1-dipheyl-2-picry-hydrazyl (DPPH) free radical scavenging assay. Therefore, leaf extracts of M. tomentosa and T. heudelotti, especially the latter, possess strong antimicrobial and antioxidant activities and should be further investigated. These activities justified the ethnomedical uses of these plants.

A study of the microbial quality and organoleptic properties of ophthalmic preparations obtained from traditional medical practitioners in South Western Nigeria

Twenty eight samples of traditional ophthalmic preparations were obtained from various traditional medical practitioners in the South Western states of Nigeria over a one-year period. They were examined for sterility, clarity, presence of particulate contamination and pH. All of them were found to be contaminated with bacteria to the order of 2.00 x 10(6) to 1.60 x 10(11) colony forming units/ml, with Pseudomonas species and other potential pathogens such as Staphylococcus aureus, Yersinia enterocolita, Micrococcus varians and others being isolated from these preparations. A rotifer Rotaria rotatoria, at the adult stage, was also isolated from one sample, this being an indication of gross faecal contamination. All the samples were also found to contain significant particulate contamination and pH values encountered varied over the range of 2.5-9.2. None of the samples was found to comply with official specifications and all of them may therefore be regarded as being potentially dangerous to the users.

A study of theIn Vivo activity of the leaf extract ofAlchornea cordifolia against multiply antibiotic resistantS. aureus isolate in mice

The effect of a 50% aqueous ethanol extract of Alchornea cordifolia (Schum and Thonn) Muell. Arg. leaf was investigated in mice which had been infected intraperitoneally with 5.0 x 10(9) cfu of Staphylococcus aureus. Dose-dependent antibacterial activity was demonstrated and the rate of survival of infected mice was improved significantly by doses between 25 and 200 mg/kg of injected extract when compared with untreated infected controls. The intraperitoneal median lethal dose of the extract was found to be 800 mg/kg.

Antimicrobial susceptibility of Helicobacter pylori isolates of dyspeptic Nigerian patients

The resistance of Helicobacter pylori to antibiotic treatment is a growing global concern, but this has not been well studied in our environment. This study sought to determine: the susceptibility of the organism to common antimicrobial agents used in its eradication therapy. Twenty H. pylori isolates from dyspeptic patients were subjected to standard procedures for sensitivity testing and the determination of minimum inhibitory concentration against amoxycillin, ciprofloxacin, clarithromycin, erythromycin, metronidazole, rifampicin and tetracycline. The study showed marked in vitro multiple antimicrobial resistance to the commonly used eradication agents. All twenty isolates were however sensitive to ciprofloxacin. The findings of marked antimicrobial resistance may affect the effectiveness of currently recommended eradication regimes. In our environment, incorporating ciprofloxacin into the existing H. pylori antimicrobial therapy may improve the outcome of eradication.

In vivo evaluation of an EIAV vector for the systemic genetic delivery of therapeutic antibodies

Lentiviral-based vectors hold great promise as gene delivery vehicles for the treatment of a wide variety of diseases. We have previously reported the development of a nonprimate lentiviral vector system based on the equine infectious anaemia virus (EIAV), which is able to efficiently transduce dividing and nondividing cells both in vitro and in vivo. Here, we report on the application of EIAV vectors for the systemic delivery of an antibody fusion protein designed for the treatment of cancer. The therapeutic potential of a single chain antibody against the tumour-associated antigen, 5T4, fused to immune enhancer moieties has been demonstrated in vitro and here we evaluate the genetic delivery of a 5T4 scFv fused to B7.1 (scFvB7) using an EIAV vector. The kinetics and concentration of protein produced following both intravenous (i.v.) and intramuscular (i.m.) administration was determined in immune competent adult mice. In addition, the immune response to the EIAV vector and the transgene were determined. Here, we show that a single injection of EIAV expressing scFv-B7 can give rise to concentrations of protein in the range of 1-5 microg/ml that persist in the sera for more than 50 days. After a second injection, concentrations of scFv-B7.1 rose as high as 20 microg/ml and levels greater than 2 microg/ml were present in the sera of all mice injected i.v. after 210 days despite the detection of antibodies against both the transgene and viral envelope for the duration of this study. These results demonstrate the potential of EIAV as a gene therapy vector for long-term production of therapeutic recombinant proteins.

Seminars on controversial issues. A review of the pharmacological approach to the management of dental anxiety in children

This paper aims to review the existing literature on the pharmacology of a number of sedative drugs used in the management of dental anxiety in the conscious child patient. Pharmacological agents may be used as a complement to behavioural techniques to assist in the management of anxiety in some paediatric dental patients. Their use may also be especially indicated in children with disabilities. These agents are usually sedative in action and do not, in themselves, eliminate anxiety but merely enhance patient acceptance by reducing arousal and modifying anticipation of danger. The agents used are varied and diverse and include nitrous oxide, benzodiazepines and narcotics. Nitrous oxide has proved to be of particular value but carries a degree of risk for the operating staff. Amongst the benzodiazepines, Midazolam has been used more frequently in recent years. It may be given by a variety of routes, including intra-nasally. Dentists who employ sedative agents and techniques should be familiar with the pharmacology of the agents selected, be cognisant of the risks and benefits of the technique employed and be able to manage any adverse events that may arise through their use.

Helicobacter pylori in the dental plaque and gastric mucosa of dyspeptic Nigerian patients

BACKGROUND

Presence of helicobacter pylori (H.Pylori) in the dental plaques may be associated with the presence of the same organism in gastric mucosa.

OBJECTIVES

To assess and compare the prevalence of H. pylori in dental plaques and gastric mucosa of dyspeptic Nigerians.

METHODS

Sixty-six consecutive patients undergoing endoscopy for investigation of dyspepsia were included in the study. A predesigned questionnaire was used to collect information on socio-demographic and other factors. Each patient also had clinical dental examination. Dental plaque scrapping was collected before endoscopy for helicobacter pylori culture, and at endoscopy, two gastric biopsy specimens were taken for culture and histology.

RESULTS

The mean age (+/- SD) of the patients was 44.8 (+/- 17.4) years (range 5 to 80 years). The positivity rate of helicobacter pylori in gastric biopsy was 35 of 66 (53.0%) while the same for dental plaque was 46 of 66 (69.7%). The correlation (Spearman's) between gastric mucosa and dental plaque colonization with helicobactor pylori was significant (R = 0.30, P = 0.01). When concordant positivity of gastric biopsy culture and histology was taken as diagnostic, the sensitivity of dental plaque culture was found to be 82.9% and the specificity was 45.2%.

CONCLUSIONS

This study revealed that helicobactor pylori has a high prevalence in the dental plaque of the population that we have studied and may therefore be of potential relevance in screening for such infection.

Bacteriological quality of skin-moisturizing creams and lotions distributed in a tropical developing country

AIMS

To evaluate the bacteriological quality of skin moisturizing products in the South-west part of Nigeria and study factors predisposing their bacterial contamination under tropical conditions.

METHODS AND RESULTS

Viable counts for bacteria exceeded 10(3) cfu ml(-1) or cfu g(-1) in 8 (16.3%) commercially available creams and lotions at time of purchase. Escherichia coli (8), Pseudomonas spp. (7), Staphylococcus spp. (9) and Bacillus spp. (6) were the most commonly recovered bacteria. Following use by volunteers, the proportion of E. coli and other Gram-negative organisms recovered increased. Organic matter, particularly in the absence of preservatives, enhanced survival and growth of bacteria in creams stored under ambient tropical conditions during challenge experiments.

CONCLUSIONS

Contaminated products are relatively uncommon but some products present a potential health hazard because they are unable to suppress the growth of organisms of likely faecal origin during use.

SIGNIFICANCE AND IMPACT OF THE STUDY

Quality assurance during manufacture, pack size, preservative evaluation, organic matter and water content were identified as factors to be considered during the development of creams and lotions for use in tropical developing countries.

Regression of established human papillomavirus type 16 (HPV-16) immortalized tumors in vivo by vaccinia viruses expressing different forms of HPV-16 E7 correlates with enhanced CD8(+) T-cell responses that home to the tumor site

Using vaccinia virus as a live vector, we show that the expression of human papillomavirus type 16 (HPV-16) E7 fused to a nonhemolytic portion of the Listeria monocytogenes virulence factor, listeriolysin O (LLO), induces an immune response that causes the regression of established HPV-16 immortalized tumors in C57BL/6 mice. The vaccinia virus construct expressing LLO fused to E7 (VacLLOE7) was compared with two previously described vaccinia virus constructs: one that expresses unmodified E7 (VacE7) and another that expresses E7 in a form designed to direct it to intracellular lysosomal compartments and improve major histocompatibility complex class II-restricted responses (VacSigE7LAMP-1). C57BL/6 mice bearing established HPV-16 immortalized tumors of 5 or 8 mm were treated with each of these vaccines. Fifty percent of the mice treated with VacLLOE7 remained tumor free 2 months after tumor inoculation, whereas 12 to 25% of the mice were tumor free after treatment with VacSigE7LAMP-1 (depending on the size of the tumor). No mice were tumor free in the group given VacE7. Compared to VacE7, VacSigE7LAMP-1 and VacLLOE7 resulted in increased numbers of H2-D(b)-specific tetramer-positive CD8(+) T cells in mouse spleens that produced gamma interferon and tumor necrosis factor alpha upon stimulation with RAHYNIVTF peptide. In addition, the highest frequency of tetramer-positive T cells was seen in the tumor sites of mice treated with VacLLOE7. An increased efficiency of E7-specific lysis by splenocytes from mice immunized with VacLLOE7 was also observed. These results indicate that the fusion of E7 with LLO not only enhances antitumor therapy by improving the tumoricidal function of E7-specific CD8(+) T cells but may also increase the number of antigen-specific CD8(+) T cells in the tumor, the principle site of antigen expression.

Quality and bioavailability of ampicillin capsules dispensed in a Nigerian semi-urban community

Five samples of ampicillin capsules with a label claim of 250 mg were purchased from different dispensing points in a small town in Nigeria. The pharmaceutical quality of the products and a sample from a batch produced by a local manufacturer was evaluated and five of the capsule samples were employed in an in vivo bioavailability study. Three of the five capsule samples from dispensing points were found to be of lower quality than the officially prescribed standards of pharmaceutical quality. The quality lapses observed were sufficient to bring about determinable differences in biological availability. The results demonstrate that ampicillin capsules of sub-standard chemical quality are being dispensed within the study sources from authorised and unauthorised sources and that this may have biological, clinical and epidemiological consequences.

Heterogeneous virulence of enteroaggregative Escherichia coli strains isolated from children in Southwest Nigeria

Enteroaggregative Escherichia coli (EAEC) has been implicated in acute and persistent diarrhea, and most strains harbor a member of a partially-conserved plasmid family (called pAA). We studied EAEC isolated from Nigerian children aged <5 years to elucidate the roles of plasmid and chromosomal EAEC loci. We tested a total of 131 EAEC strains isolated from acute diarrhea case patients and control subjects for hybridization with 8 pAA plasmid-derived and 2 chromosomal gene probes, for several in vitro phenotypes and for resistance to antimicrobial agents. Using by multiple logistic regression, we found genes encoding the AAF/II fimbriae to be strongly associated with diarrhea in this population. EAEC strains appear to be of heterogeneous virulence, and data suggest that AAF/II may be a marker for pathogenic strains.

Characterization of Escherichia coli strains from cases of childhood diarrhea in provincial southwestern Nigeria

In a study carried out in small-town and rural primary health care centers in southwestern Nigeria, 330 Escherichia coli strains isolated from 187 children with diarrhea and 144 apparently healthy controls were examined for virulence traits. Based on the results of colony blot hybridization, strains were categorized as enteropathogenic E. coli (1.8%), enterotoxigenic E. coli (2.4%), enteroinvasive E. coli (1.2%), enterohemorrhagic E. coli (0.6%), enteroaggregative E. coli (10.3%), diffusely adherent E. coli (7.9%), cell-detaching E. coli (6.9%), and cytolethal distending toxin-producing E. coli (0.9%). E. coli strains that hybridized with a Shiga toxin gene probe but lacked other characteristics usually present in enterohemorrhagic E. coli constituted 8.4% of the isolates. Ninety-seven E. coli isolates adhered to HEp-2 cells in an aggregative fashion but did not hybridize with any of the probes employed in the study. Overall the pathotypes, apart from cytolethal distending toxin-producing E. coli, were recovered both from children with diarrhea and from children without diarrhea, though to a lower extent from the healthy children. All diarrheagenic E. coli strains were associated with diarrhea (P < 0.02). Heat-stable-enterotoxin-producing enterotoxigenic E. coli showed significant association with diarrhea (P < 0.02), as did strains that demonstrated aggregative adherence to HEp-2 cells (P < 0.04), but not those that hybridized with the CVD432 enteroaggregative probe.

Antibiotic resistance in Escherichia coli from Nigerian students, 1986 1998

We tested 758 fecal Escherichia coli isolates, recovered from Nigerian students in 1986, 1988, 1990, 1994, and 1998, for susceptibility to seven antimicrobial drugs. The prevalences of strains resistant to tetracycline, ampicillin, chloramphenicol, and streptomycin were 9% to 35% in 1986 and 56% to 100% in 1998. These findings demonstrate that resistance gene reservoirs are increasing in healthy persons.

Antimicrobial spectrum of Alchornea cordifolia leaf extract

The 50% aqueous ethanol extract of Alchornea cordifolia (Schum and Thonn) Muell. Arg. leaf was screened for activity against 74 microbial strains representing aerobic, facultative and anaerobic bacteria as well as fungi. The panel of test strains included organisms from culture collections as well as clinical and environmental isolates. A concentration of 5 mg/mL of extract inhibited 36.5% of the isolates and 95.9% were inhibited by a concentration of 20 mg/mL. Only three strains, all filamentous fungi, were not susceptible to 40 mg/mL of the extract, the highest concentration tested. The extract showed the best activity against gram-positive bacteria and yeasts with inhibitory concentrations against these organisms being under 5 mg/mL. The results demonstrate that the A. cordifolia extract has a very broad spectrum of activity and suggests that it may be useful in the treatment of various microbial infections.

Socioeconomic and behavioral factors leading to acquired bacterial resistance to antibiotics in developing countries

In developing countries, acquired bacterial resistance to antimicrobial agents is common in isolates from healthy persons and from persons with community-acquired infections. Complex socioeconomic and behavioral factors associated with antibiotic resistance, particularly regarding diarrheal and respiratory pathogens, in developing tropical countries, include misuse of antibiotics by health professionals, unskilled practitioners, and laypersons; poor drug quality; unhygienic conditions accounting for spread of resistant bacteria; and inadequate surveillance.

Epoetin alfa and beta differ in their erythropoietin isoform compositions and biological properties

Epoetin alfa and beta are the two forms of recombinant DNA-derived erythropoietin (rEPO), both synthesized in Chinese hamster ovary cells, which are used for the treatment of erythropoietin (EPO)-responsive anaemias. Several batches of each of these rEPOs were compared for differences in their EPO isoform compositions by isoelectric focusing (IEF) and in a range of lectin-binding assays, and for differences in their EPO activities by in-vivo and in-vitro mouse bioassays and by immunoassay. Epoetin beta was found to differ from epoetin alfa in containing: (a) a greater proportion of more basic isoforms, (b) a greater proportion of EPO binding to Erythrina cristagalli agglutinin (which binds N-glycans with nonsialylated outer Gal beta1-4GlcNAc moieties), and (c) isoforms with higher in-vivo:in-vitro bioactivity ratios. Epoetin beta also contained slightly more than epoetin alfa of EPO binding to Lycopersicon esculentum agglutinin (which binds N-glycans containing repeating Gal beta1-4GlcNAc sequences), to the leucoagglutinin of Phaseolus vulgaris (which binds tetraantennary and 2,6-branched triantennary N-glycans) and to Agaricus bisporus agglutinin (which binds Gal beta1-3GalNAc containing O-glycans). No differences were found between the two rEPOs in their binding to a further five lectins. The differences between the isoform composition of epoetin alfa and beta, and the smaller inter-batch differences appear to be due to differences in glycosylation. The higher murine in-vivo:in-vitro bioactivity ratio of epoetin beta compared to epoetin alfa could not be explained in terms of differences in their degrees of sialylation, but was consistent with differences in their pharmacokinetics and pharmacodynamics observed in human subjects. There have been no reports that epoetin alfa differs from epoetin beta in its clinical efficacy, but the differences between epoetin alfa and beta in some analytical systems suggest that there might be a need for separate international standards for these two types of rEPO.

Bacterial capsules: a simple method for demonstration under the light microscope

It is sometimes desirable to demonstrate bacterial capsules during the routine examination of clinical isolates. Apart from the Indian ink method, methods of demonstrating bacterial capsules are not only tedious but are often non-reproducible. A combined positive-negative capsule staining procedure which is simple, rapid and reproducible is described.

A survey of nasal carriage of Staphylococcus aureus in a neonatal ward in Ile-Ife, Nigeria

The nasal carriage rate of Staphylococcus aureus among maternal-infant pairs was 18% compared with 39% among hospital staff in Ile-Ife, Nigeria during a 12-week survey. Of the newborns, 46% tested positive compared with 26% of their mothers. The S. aureus phage types recovered were predominantly of the group III type (38%); however, 28% of the strains isolated were non-typable. All the S. aureus strains were resistant to penicillin, 84% to tetracycline, and 35 and 24% were resistant to streptomycin and chloramphenicol, respectively. Altogether 19% of the strains tested were resistant to methicillin.

Transmissible trimethoprim resistance in strains of Escherichia coli isolated from cases of infantile diarrhoea

Of 190 isolates of Escherichia coli from children aged up to 5 years with diarrhoea, 72 (37.9%) were resistant to trimethoprim and of the 70 isolates tested, 38 transferred high level trimethoprim resistance (MIC greater than 1000 mg/L) into E. coli EC 1005. Of the enterotoxigenic isolates from which trimethoprim resistance was transferred, 41.2% also contained transmissible toxigenic characteristics. All the trimethoprim-resistant isolates were resistant to other antibiotics.

A study of the incidence of enterotoxigenic Escherichia coli (ETEC) secreting heat-labile toxin in two communities in south-western Nigeria

The incidence of enterotoxigenic Escherichia coli (ETEC) was investigated at oral rehydration therapy clinics in Ibadan and Ile-Ife. The incidence rate of ETEC was 74 (21.3%) of the 347 diarrhoeal stool samples examined. ETEC incidence rate was 25.1% in Ibadan and 12.0% in Ile-Ife. Children aged between 0 and 18 months appeared most susceptible in both centres. A higher incidence of ETEC occurred among the male (31.9%) than female (17.0%) subjects at Ibadan but no such difference was obtained at Ile-Ife where 12.5% of males and 11.4% of female subjects were infected. The results obtained in this study suggest ETEC played a prominent role in infantile diarrhoea in the two centres studied.

Incidence of multiple antibiotic resistances in organisms isolated from cases of infantile diarrhoea in a Nigerian oral rehydration therapy clinic

A total of 247 bacterial isolates were obtained from diarrhoeal patients aged 0-60 months in an oral rehydration therapy clinic in Ibadan and tested for sensitivity to 11 antibiotics using the disc diffusion method. Fifty isolates obtained from apparently healthy age-matched controls were similarly tested. The results show that 6(2.4%) of the isolates obtained from the diarrhoeal children were resistant to all the 11 antibiotics used in the test and that most of the others were resistant to several antibiotics. Similarly, a very considerable percentage of isolates obtained from children in the control group were found to be resistant to several antibiotics. It is therefore apparent that there is a high incidence of multiply-antibiotic-resistant isolates within the sample environment.

Transfer of low level trimethoprim resistance in faecal isolates obtained from apparently healthy Nigerian students

Twenty-four of 63 enteric Gram-negative organisms (38.1%) which were isolated from 35 apparently healthy Nigerian students were found to have low trimethoprim resistance (MIC less than 1000 mg/l). These isolates were also found to be resistant to several other antibiotics and trimethoprim resistance was found to be transferable from 15 (62.5%) of the trimethoprim resistant organisms into E. coli EC 1005. It is likely that the high percentage of trimethoprim resistance encountered in this study is related to the high rate of resistance transfer which was observed.

Trimethoprim resistance in urinary tract pathogens in two Nigerian hospitals

One hundred and twenty eight (63.3%) of 202 isolates of Gram-negative bacilli from urinary infections in patients in two Nigerian hospitals were found to be resistant to trimethoprim. Of the trimethoprim-resistant organisms, 111 (86.7%) showed MICs of trimethoprim in excess of 1000 mg/l. Trimethoprim resistance was found to be transferable from 65 (50.8%) of these highly resistant organisms into Escherichia coli EC1005. The trimethoprim-resistant strains obtained in the study were also resistant to at least one other antibiotic of the nine tested.

A long-term study of the nasal carriage of Staphylococcus aureus in healthy Nigerian students

892 nasal swabs were collected from 50 pharmacy students (25 male and 25 female) over a period of 15 months. 323 (36.2%) contained Staphylococcus aureus and analysis of the results showed that 19 (38%) of the subjects were true nasal carriers of S. aureus, 23 (46%) were non-carriers, and the other 8 (16%) were sporadic non-carriers. 84% of the 162 isolates tested were resistant to penicillin and 58% were resistant to tetracycline.

Nasal carriage of Staphylococcus aureus in a population of healthy Nigerian students

The nasal carrier-rate of Staphylococcus aureus in 548 Nigerians aged 9-32 years and attending various educational establishments was 56.4%. This rate decreased with increasing age. A significantly greater proportion of females (65.0%) than males (46.5%) were carriers, but the excess in females was apparent only in subjects aged greater than 20 years. Mucoid strains of S. aureus, which gave a negative slide-coagulase reaction, were found in 21.5% of carriers aged 10-15 years, but were absent from members of other age-groups. A considerable proportion of all the strains tested were resistant to commonly used antibiotics.

Antimicrobial sensitivity patterns of hospital and non-hospital strains of Staphylococcus aureus isolated from nasal carriers

The nasal carriage rate of Staphylococcus aureus was significantly higher in hospitalized persons (children, adult females and staff) - 53.8%, - than in similar persons at a local clinic - 29.8% (P less than 0.001) - in Ile-Ife, Nigeria. However, unlike studies carried out elsewhere, a higher proportion of S. aureus strains obtained from persons at the clinic were resistant to commonly used antimicrobial agents than were strains isolated in the hospital. This has been attributed to the ease at which these drugs can be obtained by the general population and used unsupervised and indiscriminately. Methicillin was the most effective antimicrobial agent against pathologic staphylococci (2.2% resistance), followed by erythromycin (16.5% resistance), co-trimaxozole (28.0% resistance), chloramphenicol (76.9% resistance), tetracycline (78.6% resistance) and penicillin and ampicillin (97.8% resistance). The widespread resistance of S. aureus to penicillin and ampicillin (and other antimicrobial agents) is of clinical significance in the treatment of post-operative infections, since carriers are reportedly more prone to such infections than are non-carriers.

Nasal carriers of coagulase-positive staphylococci in a Nigerian hospital community

Nasal swabs taken from 324 subjects in a Nigerian hospital were examined for the presence of coagulase positive staphylococci. The subjects used in this study included the patients, staff and "auxiliaries" aged from one day to 70 years. The results obtained show that approximately 50% of all the subjects were nasal carriers of Staphylococcus aureus and that age, occupation and length of the subjects' stay in hospital had a significant effect on this figure. It was also found that there is no significant difference between the prevalence of nasal carriage of S. aureus amongst the hospital staff and the patients.