Tenofovir diphosphate in dried blood spots and HIV-1 resistance in South Africa.

BACKGROUND: Suboptimal antiretroviral (ART) adherence can lead to virologic failure with consequent HIV-1 resistance. Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is a powerful biomarker of cumulative adherence, predictive of future viremia. It has been associated with resistance in Persons With HIV (PWH) in South Africa and the US. We explored the relationship of TFV-DP concentrations with antiretroviral drug resistance at the time of treatment failure in SA. METHODS: Adult PWH from health clinics in Cape Town, South Africa on efavirenz-based first-line ART containing tenofovir disoproxil fumarate (TDF) with an undetectable (< 50 copies/mL) HIV-1 viral load (VL) were prospectively enrolled in an observational cohort for 12 months. Monthly study visits included blood collection for HIV-1 VL and DBS for TFV-DP. The first confirmed viral breakthrough (VB) > 400 copies/mL triggered HIV-1 genotyping at the subsequent visit. An electronic adherence (EA) device monitored ART adherence in real-time, estimated as a percent for the 30-days prior to VB. Wilcoxon rank sum test was used to compare median [IQR] TFV-DP by genotype outcome. RESULTS: Of 250 individuals, (n = 195, 78% women), 21 experienced VB, with a median of 5 [4;7] months on study, and a median EA of 33.3 [13.3;53.3]%. Demographic characteristics between those with and without VB were similar. Median VL at VB was 4.0 [3.2;4.5] log copies/mL. TFV-DP concentrations trended down towards the VB visit. Median TFV-DP concentrations were significantly higher in those HIV-1 genotype did not amplify due to being virally suppressed at the subsequent visit (n = 10; 380 [227-661] fmol/punch, p = 0.035; EA 45 [24.9; 59.2]%); than in those who were successfully genotyped with evidence of drug resistance (n = 5, 241 [150-247] fmol/punch, EA 20 [6.7;36.7]%) and in individuals who did not have resistance (n = 3, 39.9 [16.6; 93.9] fmol/punch; EA 33.3 [16-38]%). Three genotype collections were not done. Only non-nucleoside reverse transcriptase inhibitor-associated mutations were identified on resistance testing. (K103N, E138K, Y118H). CONCLUSION: TFV-DP in DBS showed a step-wise inverse relationship with VB and drug resistance, with evidence of low cumulative ART adherence in PWH who developed antiretroviral resistance. Monitoring TFV-DP concentrations could be a valuable tool for predicting future VB and future resistance.

Measuring ART Adherence Among Young Adults with Perinatally Acquired HIV: Comparison Between Self-report, Telephone-Based Pill Count, and Objective Pharmacologic Measures.

Tenofovir diphosphate (TVF-DP) can be quantified in red blood cells (RBCs) and dried blood spots (DBS) and can objectively measure ART adherence and predict viral suppression. Data on the association of TFV-DP with viral load are very limited in adolescents and young adults (AYA) living with perinatally-acquired HIV (PHIV), as are data comparing TFV-DP to other measures of ART adherence, such as self-report and unannounced telephone pill count. Viral load and ART adherence (self-report, TFV-DP and unannounced telephone pill count) were assessed and compared among 61 AYAPHIV recruited from an ongoing longitudinal study (CASAH) in New York City.

The Impact of HIV-Associated Neurocognitive Impairment on Driving Performance in Commercial Truck Drivers.

Driving ability can be diminished amongst people with HIV with associated neurocognitive impairment (NCI). We explore the relationship between HIV status, NCI and driving ability in professional truck drivers. Forty male professional drivers (20 HIV-positive; mean age = 39.20 ± 7.05) completed a neuropsychological test battery, two driving simulator tasks that assessed driving ability, and a driving history and habits questionnaire. A higher proportion of HIV-positive drivers exhibited impaired overall cognitive performance (p ≤ 0.001). Overall, drivers with NCI (defined as z ≤ 1.00) were more likely than those without NCI to crash (p = 0.002). There were no significant between-group (HIV-positive versus HIV-negative) differences with regard to self-reported on-road driving events. Professional drivers with NCI, as measured on a driving simulator, are at increased risk of making driving errors under high-risk conditions compared to their neurocognitively normal counterparts. These data should inform driver health management with regard to annual medical screening and surveillance.

RESUMEN: La capacidad de conducción puede verse disminuida entre las personas con VIH con deterioro neurocognitivo asociado (neurocognitive impairment, NCI). Exploramos la relación entre la situación frente al VIH, el NCI y la capacidad de conducción en conductores profesionales de camiones. Cuarenta conductores profesionales masculinos (20 seropositivos, edad media = 39.20 ± 7.05) completaron una batería de pruebas neuropsicológicas, dos tareas de simulador de conducción que evaluaron la capacidad de conducción y un cuestionario de hábitos y antecedentes de conducción. Una mayor proporción de conductores VIH positivos exhibió un desempeño cognitivo general deficiente (p ≤ 0.001). En general, los conductores con NCI (definido como z ≤ 1.00) tenían más probabilidades de chocar que aquellos sin NCI (p = 0.002). No hubo diferencias significativas entre los grupos (VIH positivo frente a VIH negativo) con respecto a los eventos autoinformados de conducción en carretera. Los conductores profesionales con NCI, según lo medido en un simulador de conducción, tienen un mayor riesgo de cometer errores de conducción en condiciones de alto riesgo en comparación con sus homólogos neurocognitivamente normales. Estos datos deberían informar a la gestión de la salud del conductor en lo que respecta a la vigilancia y los exámenes médicos anuales.

Construct Validity Supports Use of a Novel, Tablet-Based Neurocognitive Assessment for Adolescents and Young Adults Affected by Perinatal HIV from Vulnerable Communities in the United States.

Construct validity of novel tablet-based neurocognitive tests (in the NeuroScreen app) measuring processing speed, working memory, and executive functioning in adolescents and young adults (AYA) living with perinatally-acquired HIV (PHIV) and perinatal HIV-exposure without infection (PHEU) was examined. Sixty-two AYA (33 PHIV, 29 PHEU) were recruited from an ongoing longitudinal study (CASAH) in New York City. Medium to large and statistically significant correlations were found between NeuroScreen and gold standard, paper-and-pencil tests of processing speed, working memory, and executive functioning. Results provide partial support for NeuroScreen as an alternative to cumbersome paper-and-pencil tests for assessing neurocognition among HIV-affected AYA.

Empowering Lay-Counsellors with Technology: Masivukeni, a Standardized Multimedia Counselling Support Tool to Deliver ART Counselling.

Lay-counsellors in resource-limited settings convey critical HIV- and ART-information, and face challenges including limited training and variable application of counselling. This study explored lay-counsellors and Department of Health (DoH) perspectives on the utility of a multimedia adherence counselling program. Masivukeni, an mHealth application that provides scaffolding for delivering standardized ART counselling was used in a 3-year randomized control trail at two primary health care clinics in Cape Town, South Africa. In this programmatic and descriptive narrative report, we describe the application; lay-counsellors' response to open-ended questions regarding their experience with using Masivukeni; and perspectives of the City of Cape Town and Western Cape Government DoH, obtained through ongoing engagements and feedback sessions. Counsellors reported Masivukeni empowered them to provide high quality counselling. DoH indicated strong support for a future implementation study assessing feasibility for larger scale roll-out. Masivukeni has potential as a counselling tool in resource-limited settings.

Effect of tampon wraps on production of toxic shock syndrome toxin 1.

The influence of tampon wraps on the production and distribution of toxic shock syndrome toxin 1 (TSST-1) was investigated with use of a disk-membrane-agar method. Filter membranes (45 micron) overlaying agar medium in 50-mm petri dishes were spread-inoculated with a TSST-1-producing strain of Staphylococcus aureus and covered with 0.5 mL of whole citrated rabbit blood. Disks of tampon core materials with and without wraps were placed on the inoculated membranes and incubated at 37 degrees C in 5% CO2 in air. Eight wraps with each of 14 tampon core materials were tested to determine the amount of toxin in the agar layer, a quantity considered an indicator of the relative amounts of toxin available for absorption in vivo. The average level of toxin in the agar layer with any particular wrap compared with that in the agar layer with no wrap was higher with five wraps, lower with two wraps, and essentially the same with one wrap. The lower levels of toxin were obtained with one wrap that had a starch binder and with one that contained the surfactant Standamul 1414-E. Standamul 1414-E has been reported to be an inhibitor of growth of and production of TSST-1 by S. aureus.

Production of toxic shock syndrome toxin 1 by Staphylococcus aureus as determined by tampon disk-membrane-agar method.

The influence of 17 commercially available tampons on production of toxic shock syndrome toxin 1 (TSST-1) by Staphylococcus aureus was investigated by using a tampon disk method. Filter membranes overlaying agar medium (with or without blood) in small petri dishes were spread inoculated with a TSST-1-producing strain of S. aureus. Disks cut from unrolled tampons were pressed and laid on the inoculated membranes; incubation was for 19 h at 37 degrees C with 5% CO2 in air. CFU on the membranes and in the disks were enumerated, and the presence of TSST-1 in the disks and in the agar layers was determined. Tampons made of different materials supported characteristic levels of cell growth and toxin production in the tampon. Colonization of the interface surface of the tampon disks was heavy. The number of CFU extracted from the tampon disks ranged from 5 X 10(10) to 82 X 10(10). There was little variation in the CFU recovered from the membranes ([1.9 +/- 0.4] X 10(11)). Sixty to 170 micrograms of TSST-1 was recoverable from the agar, with an additional 10 to 90 micrograms recoverable from tampon disks, depending on the type of tampon disk. The amount of toxin in the agar layer from the various tampon disks was relatively constant and indicated an important contribution of toxin from vaginal S. aureus cells not growing in the tampon. The main role of tampons in toxic shock syndrome may be that of providing a fibrous surface for heavy colonization and sufficient air for TSST-1 production.

Toxic shock syndrome--the role of the toxin.

From isolates of Staphylococcus aureus derived from patients suffering from toxic shock syndrome a toxin was identified by tests in monkeys and was found to be distinct from the enterotoxin responsible for staphylococcal food poisoning. When purified, this TSS toxin (TSST-1) was characterised and used to generate antibodies in rabbits. Only a small proportion of routine staphylococcal isolates produce TSST-1, though it is clear that this toxin has existed for some years. At the same time, TSST-1 producing staphylococci have been isolated in every continent, yet very few cases of toxic shock syndrome have been recognised in developing countries. Using the purified TSST-1, human sera have been examined for the presence of antibodies. Patients with the disease had either no antibodies, or low titres.

Identification, purification, and some physicochemical properties of staphylococcal enterotoxin C3.

A third staphylococcal enterotoxin C (C3) has been identified, purified, and characterized. Staphylococcal enterotoxin C3 was identified from a Staphylococcus aureus isolated received from England. The purified toxin was determined by gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be a simple protein with a molecular weight of 26,900. The isoelectric point of the major band was determined by isoelectric focusing in polyacrylamide gels to be 8.15. The reaction of enterotoxin C3 with its specific antibody was not affected by tryptic digestion at pH 8.0 or peptic digestion at pH 4.5. The enterotoxin C3 consisted of 236 amino acid residues. Serine was shown to be the NH2-terminal amino acid residue by end group analysis. The protein was highly emetic in cynomolgus monkeys both per os and intravenously.

Purification and some physicochemical properties of toxic-shock toxin.

A procedure for the purification of a protein marker for the staphylococci isolated from toxic-shock syndrome patients has been developed. The purification procedure involves the removal of the toxic protein from culture supernatant fluids of toxic-shock syndrome associated Staphylococcus aureus strains FRI-1169 and FRI-1183 by batch absorption with CG-50 resin, ion-exchange chromatography on CM-Sepharose CL-6B, and gel permeation chromatography on Sephacryl S-200. The purified toxin is a simple protein with a molecular weight of 24 000 +/- 500 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point of the major band is 7.0 as determined by isoelectric focusing in polyacrylamide gels. The TS-toxin's reactivity with its specific antibody is not affected by tryptic digestion at pH 8.0 but is slowly reduced by treatment with pepsin at pH 4.5. The TS-toxin consists of 188 amino acid residues. Serine was shown to be the NH2-terminal amino acid residue by end-group analysis. Initial studies indicated the protein was emetic; thus tentatively it was called staphylococcal enterotoxin F. In this paper it is called TS-toxin because the emetic action in monkeys has not been confirmed.

An enterotoxin-like protein in Staphylococcus aureus strains from patients with toxic shock syndrome.

An enterotoxin-like protein, tentatively labeled enterotoxin F, was isolated from Staphylococcus aureus strains taken from patients with toxic shock syndrome. Antibodies specific for enterotoxin F were prepared in rabbits. Use of these antibodies showed that 130 (91.5%) of 142 S. aureus strains from patients with toxic shock syndrome produced enterotoxin F. Strains from toxic shock patients in eight other countries were identified as enterotoxin F producers. Only a small number of S. aureus strains from sources other than patients with toxic shock syndrome were found to produce enterotoxin F. Twenty-one of 111 controls had low antibody titers (less than 1:100) to enterotoxin F whereas 86 of 92 toxic shock patients had low acute phase antibody titers (less than 1:100) to enterotoxin F. Eight of 52 patients had serum conversion as shown by an increase in antibody titer to enterotoxin F in sera taken 21 to 60 days after onset of the illness. It may be possible to identify persons susceptible to toxic shock syndrome by measuring their antibody titer to enterotoxin F.

A new staphylococcal enterotoxin, enterotoxin F, associated with toxic-shock-syndrome Staphylococcus aureus isolates.

612 (93.8%) of 65 Staphylococcus aureus strains isolated from 65 patients with toxic-shock syndrome (TSS) produced an enterotoxin-like protein, tentatively identified as staphylococcal enterotoxin F (SEF). One of the other strains produced staphylococcal enterotoxin B and another exterotoxin C. In two blind studies all 34 TSS-associated S. aureau strains examined and 3 (11.5%) of 26 control S. aureau strains produced SEF. 2 of the latter strains were isolated from the vaginas of women who had no history of TSS. SEF was purified, and specific antibodies to it were prepared. Only 4 (4.6%) of 87 S. aureau strains from other sources were found to produce SEF. 5 (17.2%) of 29 TSS patients whose acute sera were available had anti-SEF antibody present in titres of greater than or equal to 1:100 as determined by radioimmunoassay, compared with 44 (78.6%) of 56 controls--demonstrating a greater serosusceptibility of TSS patients to SEF. It is suggested that staphylococcal enterotoxin, particularly SEF, may be a cause of the signs and symptoms of TSS.

Antibodies to staphylococcal enterotoxin in laboratory personnel.

Eighty-five percent of laboratory personnel working with staphylococcal enterotoxin had antibodies to enterotoxin in their sera, whereas only 23% of the control group had antibodies specific for enterotoxin. Two persons who carried enterotoxin B-producing staphylococci in their noses, throats, or both, had antibodies to enterotoxin B in their sera.

Isolation of specific and common antibodies to staphylococcal enterotoxins B, C1, and C2.

Staphylococcal enterotoxins C1 and C2 elicit the production of antibodies in rabbits that give precipitin reactions with both toxins and gel diffusion plates. These enterotoxins also elicit the production of antibodies that are specific for each of the enterotoxins. Enterotoxin B elicits the production of antibodies in some rabbits that react with enterotoxins B, C1, and C2 in gel diffusion plates and in radioimmunoassay. Antibodies specific for enterotoxin B are produced also. Enterotoxin C1 elicits the production of antibodies that cross-react weakly with enterotoxin B, indicating that the antigenic sites involved in the cross-reactions are not identical in the two toxins. The antibodies have been isolated by affinity chromatography.

Isolation of specific and common antibodies to staphylococcal enterotoxins A and E by affinity chromatography.

Specific and common antibodies to staphylococcal enterotoxins A and E (SEA and SEE) were isolated from anti-SEA and anti-SEE antisera by affinity chromatography. Anti-SEA and anti-SEE antisera were passed through a column with the cross-reacting enterotoxin coupled to a CNBr-activated Sepharose 4B matrix. Specifically bound common antibodies were eluted with NaSCN. The isolated specific antibodies reacted only with the homologous enterotoxin, whereas the common antibodies gave a reaction of identify with both enterotoxins in double gel diffusion plates. The common antibodies had a higher titer against SEE than against SEA. The significance of the isolation of antibodies common to two separate protein molecules is discussed.

Identification of enterotoxin E.

Identification of a new enterotoxin was accomplished by purification of the enterotoxin produced by staphylococcal strain FRI-326 and by preparation of specific antitoxin to the enterotoxin. Toxicity of the preparations was determined in rhesus monkeys, and specificity of the enterotoxin-antitoxin reaction was determined in gel diffusion plates. The enterotoxin was designated enterotoxin E.

Relationship between staphylococcal antiserum titer and zone development on immune serum plates.

A workable relationship was established between the standard serum titers of staphylococcal immune antisera and the development of precipitin zones on serum agar around colonies of staphylococcal strains producing homologous antigens (enterotoxins). The standard titer of a serum is defined as the reciprocal of that serum dilution which, with 10 mug of pure enterotoxin per ml, will give a precipitin zone 10 mm in length in single gel-diffusion tubes after 7 days of incubation at 25 C. A numerical scale was set up for determining the intensity of precipitin zones on serum agar. A reading of 3 was considered optimum. This correlated well with a standard serum titer of 25, when 1 ml of such a serum was used per 20 ml of medium per serum plate. From this relationship, the minimum volume of serum required to give optimum precipitin zone development can be calculated.