[Determination of amoxicillin in human plasma by high performance liquid chromatography and its pharmacokinetics]

A rapid and sensitive assay for amoxicillin in human plasma has been developed using reversed phase high performance liquid chromatography. Plasma samples were prepared for analysis by addition of internal standard (tinidazole) followed by protein precipitation with HClO4. A YWG C18H37 column as stationary phase and a 0.033 mol.L-1 phosphate buffer (pH 7.2)--methanol mixture (85:15) as mobile phase were used with the UV detector set at 229 nm. The calibration curve was linear in the range from 0.2 microgram.ml-1 to 20.0 micrograms.ml-1 with gamma > 0.999. The analytical recovery of amoxicillin from plasma was > 86.7%. The relative standard deviations for within-day and between-day were < 5.48% and < 8.29%, respectively. Following oral administration of 500 mg in human volunteers, the peak levels of amoxicillin in plasma averaged 6.88 +/- 2.25 micrograms.ml-1 at 84.4 +/- 21.1 min. The mean half life time for amoxicillin was 62.8 +/- 14.6 min.

Geographical distribution of HIV-1 group O viruses in Africa

OBJECTIVE

To determine to what extent HIV-1 group O strains are present in different African countries.

MATERIALS AND METHODS

A total of 14,682 samples of sera from a range of patients from 12 different African countries were tested. All the sera were tested with an enzyme-linked immunosorbent assay (ELISA) using a combination of V3 peptides from ANT-70 and MVP-5180. Samples reactive in ELISA were retested in a line immunoassay (LIA-O). Samples reactive in ELISA were also retested with an in-house Western blot to determine the presence of antibodies to gp120 of HIV-1 ANT-70. Polymerase chain reaction was performed on HIV-1 group O and group O indeterminate sera.

RESULTS

Of all the sera samples tested, only 19 sera had antibodies to group O V3 peptides exclusively and 46 were indeterminate for group O infection in LIA-O. The highest prevalence of HIV-1 group O infection among HIV-positive sera was observed in Cameroon (2.1%) and neighbouring countries, 1.1% in Nigeria and 0.9% in Gabon. The lowest rates were seen in west Africa: 0.07% in Senegal, 0.14% in Togo, 0.16% in Chad and 0.3% in Niger. Group O sera were observed in almost all the population categories tested. The ANT-70 V3 peptide in LIA-O was reactive with all of the sera considered to be HIV-1 group O antibody positive by LIA, versus 78.9% for the MVP-5180 peptide. Thirteen out of 19 group O samples of sera were tested in PCR. Eight samples were identified as group O by specific group O pol and/or V3 primers; in the remaining five samples no HIV RNA could be detected. Of the indeterminate sera samples, two were identified as group O.

CONCLUSION

In eight of the 12 countries tested, antibodies to group O viruses were identified. Numbers of HIV-1 group O viruses are low. Their presence is not restricted to Cameroon and neighbouring countries but can also be found in west and south-east Africa.

Neopterin, beta 2-microglobulin, and acute phase proteins in HIV-1-seropositive and -seronegative Zambian patients with tuberculosis

Neopterin is a biochemical marker for the activation of the cell-mediated immune system. We measured neopterin, beta 2-microglobulin, and acute phase proteins in 31 HIV-seropositive and -seronegative Zambian patients with tuberculosis, using stored sera that had been obtained at the beginning and at end of antituberculosis treatment. In both HIV-seropositive and -seronegative patients neopterin and acute phase proteins were elevated when tuberculosis was initially diagnosed and fell during treatment. In contrast, the mean beta 2-microglobulin level increased during antituberculous therapy in the HIV-seropositive group. Serum neopterin levels at diagnosis were correlated with other parameters of disease activity (fever, anemia, and weight loss). In both groups, patients with persistently elevated neopterin levels at the end of treatment were more likely to suffer relapse of tuberculosis or other adverse health events in the subsequent follow-up period. Neopterin can be used to monitor the response to antituberculous therapy in both HIV-seropositive and -seronegative patients and may have a prognostic value for the patients' wellbeing in the follow-up period.

The prevalence and aetiology of persistent diarrhoea in adults in urban Zambia

As the AIDS pandemic has spread, diarrhoea in adults has become a major burden on health care institutions in central Africa and on the families of sufferers. In order to assess the magnitude of the problem, we carried out a survey of households in a high population density township of Lusaka to determine the prevalence of persistent diarrhoea in adults. We also carried out a study of the causes of persistent diarrhoea in patients attending the University Teaching Hospital, Lusaka. The community survey assessed 460 households, representing a sample of 1440 adults. 94 adults were reported as having had diarrhoea in the 2 weeks prior to the survey, implying an attack rate of 1.74 per adult per year. Of these 94 cases, six had diarrhoea of between 2 and 4 weeks duration, and ten had diarrhoea of over 4 weeks duration. In the hospital study, 75 (97%) out of 77 patients with diarrhoea of over 1 months' duration were HIV seropositive; potentially pathogenic parasites were found in 61/75 (81%) of seropositives. This information indicates that persistent diarrhoea in adults, mostly related to HIV infection, is likely to be an important and growing reservoir of enteric pathogens and represents a significant burden on hospitals and relatives. This emerging problem in sub-Saharan Africa may foreshadow developments in other continents.

The increased burden of tuberculous lymphadenitis in central Africa: lymph node biopsies in Lusaka, Zambia, 1981 and and 1990

In order to assess the effect of the HIV epidemic on lymph node biopsies in Central Africa, HIV-1 serology was tested on a cohort of patients undergoing node biopsy in Lusaka in 1990, and the histology of all lymph nodes biopsied in Lusaka in 1981 and 1990 was reviewed. One hundred and eighteen lymph nodes were biopsied in 1981 and 351 in 1990. Cases of tuberculous lymphadenitis increased from 52 (31 children and 21 adults) in 1981 to 186 (22 children, 160 adults, four patients unknown age) in 1990. Sixty-eight of 77 adults (88%) with tuberculous lymphadenitis in 1990 tested HIV-positive. Cases of histology suspicious of primary HIV lymphadenopathy and nodal Kaposi's disease also increased. Cases of malignant lymphadenopathy and overall number of surgical biopsies remained equivalent for 1981 and 1990. The study concludes that the HIV epidemic has led to a large increase in diagnostic lymph node biopsies in Lusaka, mostly through an increase in HIV-related adult tuberculous lymphadenitis.

[Effects of high dose pulse oral calcitriol on secondary hyperparathyroidism in patients with end-stage renal disease]

To evaluate the therapeutic effects of high dose pulse oral calcitrol, 3.5 micrograms calcitrol three times a week and calcium carbonate were administered to 13 patients with end-stage renal disease on chronic hemodialysis with hyperparathyroidism refractory to conventional calcitrol therapy. Serum parathyroid hormone and osteocalcin were detected by radioimmunoassay. Serum parathyroid hormone level of the patients decreased from 1111 +/- 344 ng/L to 492 +/- 218 ng/L by 57.5 +/- 11.5 percent (P < 0.01) in 6 months after the beginning of treatment. Both serum alkaline phosphatase and osteocalcin levels declined markedly, and correlated positively with that of parathyroid hormone. Plasma calcium concentration was markedly elevated, but no obvious increase of plasma phosphate was found. High dose pulse oral calcitrol was effective on secondary hyperparathyroidism. During the course of treatment timely and individual adjustment of calcitrol dose and dialysate calcium concentration is essential.

Importance of human immunodeficiency virus-associated lymphadenopathy and tuberculous lymphadenitis in patients undergoing lymph node biopsy in Zambia

The relative importance of human immunodeficiency virus (HIV)-associated lymphadenopathy amongst patients presenting for lymph node biopsy in Central Africa is unknown. HIV-1 serology and histology of patients undergoing superficial lymph node biopsy during 1989-1990 in Lusaka, Zambia, were examined in a prospective cohort study of HIV serology and by retrospective review of laboratory records. Of 727 lymph nodes biopsied in Lusaka in 1989-1990, 380 (52 per cent) showed tuberculous lymphadenitis, 160 (22 per cent) histology suggestive of primary HIV lymphadenopathy and 66 (9 per cent) nodal Kaposi's disease. HIV serology was tested in 280 adults and was positive in 91 per cent (255 patients), including 89 per cent (153 of 171) of those with tuberculous lymphadenitis, 98 per cent (63 of 64) of those with histology suspicious of primary HIV lymphadenopathy and all (24 of 24) with nodal Kaposi's disease. Other HIV-associated lymphadenopathy included nodal lymphomas and lymphoepithelial cysts. HIV serology was tested in 22 children and was positive in eight, including four of 14 with tuberculous lymphadenitis. It is concluded that HIV-associated lymphadenopathy, especially tuberculous lymphadenitis, is very common amongst patients presenting for lymph node biopsy in Central Africa.

Hepatitis B virus infection among pregnant women in Zambia

The prevalence of hepatitis B virus (HBV) markers was studied in pregnant women attending antenatal clinics in Zambia. A total of 2,098 pregnant women were recruited into the study at three urban health centres in Lusaka, the capital city and four district hospitals in rural areas of different provinces of Zambia. The overall prevalence of HBsAg was 6.5% (137/2,098), and HBeAg was present in 16.1% (22/137) of those positive for HBsAg. Antibody positive rate (HBsAb and/or HBcAb) was 51.3% in randomly selected HBsAg negative samples. HBsAg positive rate varied between 3.3% and 13.6% in each study sites. Prevalence for both HBsAg and antibodies to HBV were significantly higher in rural areas (district hospitals) than in urban areas (urban health centres in Lusaka). These data show that although HBV is endemic in Zambia, the prevalence varies from region to region.

Recruitment to a trial of tuberculosis preventive therapy from a voluntary HIV testing centre in Lusaka: relevance to implementation

To determine the number of clients attending for voluntary human immunodeficiency virus (HIV) testing who are able to enter a trial of preventive therapy for tuberculosis, and the factors that determine who receives therapy, we studied 475 consecutive people attending for an HIV test at Lusaka's first voluntary HIV testing centre and the preventive therapy study clinic at the University Teaching Hospital, Lusaka, Zambia. Semi-structured interviews were conducted by counsellors and collated with recruitment data from the trial. Two hundred and twenty-five people were seropositive, of whom 201 returned to collect their results; 77 (38%) of these (16% of the total number screened) entered the trial. Reasons for not entering the trial included exclusion by trial protocol (30), including 18 who had active tuberculosis; psychological adjustment to a positive result (27); death (6); worries about confidentiality (3); the experimental nature of the trial (12); attitudes of staff in the hospital (5); and cost of transport (7). Targeting preventive therapy at those who are already choosing to be tested for HIV seems appropriate and may be cost-effective. Although visiting a hospital may deter some people, the prevalence of active tuberculosis among this group emphasized the importance of arranging adequate screening facilities.

HEp-2 cell-adherent Escherichia coli in patients with human immunodeficiency virus-associated diarrhea

Diarrhea occurs commonly in African human immunodeficiency virus (HIV) infections. A case-control (HIV-positive vs. -negative) study of adults with diarrhea was done in Lusaka, Zambia, to determine the prevalence of intestinal infection by HEp-2 cell-adherent Escherichia coli. Adherent E. coli were more common in HIV-positive patients with acute diarrhea than among HIV-negative controls (60% vs. 33%) and were found significantly more often in HIV-positive patients with chronic diarrhea than among HIV-negative controls with chronic diarrhea (79% vs. 17%, P < .002). Adherent strains were found significantly more often among HIV-positive patients (69%) than in 22 asymptomatic subjects (36%, P < .02). The HEp-2 cell adherence of the E. coli strains did not show a common pattern. Adherent bacteria were also observed in colonic biopsies from 32% of Zambians with chronic diarrhea who underwent endoscopy. Adherent E. coli may be an important cause of HIV-associated diarrhea in Zambia.

Use of saliva as an alternative to serum for HIV screening in Africa

Saliva has been recommended as a safe and effective alternative to serum for enzyme-linked immunosorbent assay (ELISA) for HIV antibodies in surveillance programmes in developing countries. We evaluated the use of saliva specimens for detection of HIV antibodies using three different commercially available ELISAs. Saliva specimens from 107 patients selected at random from HIV high-risk (38), medium-risk (27) and low-risk (42) areas of the hospital were screened with the Wellcozyme HIV1 + 2 GACELISA VK61 (recommended for use with saliva), Wellcozyme HIV1 + 2 VK54/55 and Wellcozyme HIV-1 recombinant VK56/57. Of the 107 patients, 50 were positive and 57 negative for antibodies to HIV on confirmatory Western blot testing. For detection of antibodies to HIV in saliva, the Wellcozyme HIV1 + 2 GACELISA VK61 had a sensitivity and a specificity of 98%, the Wellcozyme HIV-1 recombinant VK56/57 a sensitivity and specificity of 96%, and the Wellcozyme HIV1 + 2 VK54/55 a sensitivity of 94% and a specificity of 95%. For detection of antibodies to HIV in serum, the Wellcozyme HIV-1 recombinant VK56/57 had a sensitivity and a specificity of 100%, the Wellcozyme HIV1 + 2 GACELISA VK61 a sensitivity and a specificity of 98%, and the Wellcozyme HIV1 + 2 VK54/55 a sensitivity and a specificity of 96%. This study illustrates that saliva can be used as an alternative to serum for screening for anti-HIV antibodies in African patients.

The impact of human immunodeficiency virus on response to treatment and recurrence rate in patients treated for tuberculosis: two-year follow-up of a cohort in Lusaka, Zambia

To examine the effect of HIV on response to treatment and recurrence rate in patients with tuberculosis (TB), we have followed 239 previously untreated, adult, TB patients in a prospective cohort study in Lusaka, Zambia. One hundred and seventy-four (73%) were HIV-1 antibody positive. Patients with sputum smear positive, miliary, or meningeal TB were prescribed 2 months daily streptomycin, thiacetazone, isoniazid, rifampicin, pyrazinamide followed by 6 months thiacetazone and isoniazid; others, 2 months streptomycin, thiacetazone and isoniazid followed by 10 months thiacetazone and isoniazid. Thirty-five per cent of HIV-positive (HIV+ve) and 9% of HIV-negative (HIV-ve) patients were known to have died before the scheduled end of treatment. Surviving HIV+ve patients showed weight gain and improvement in symptoms and laboratory and radiological findings similar to HIV-ve patients. The risk of cutaneous drug reaction was 17% (95% CI: 12-25%) in HIV+ve, and 4% (1-13%) in HIV-ve patients. Severe rashes were attributed to thiacetazone. Recurrence of active TB was examined among 64 HIV+ve and 37 HIV-ve patients who successfully completed treatment, with mean follow-up after the end of treatment of 13.5 and 16.8 months, respectively. The rate of recurrence was 22/100 person years (pyr) for HIV+ve patients and 6/100 pyr for HIV-ve patients, giving a recurrence rate ratio of 4.0 (95% CI 1.2-13.8, P = 0.03).

Rotavirus gastro-enteritis in hospitalized children with acute diarrhoea in Zambia

The clinical and epidemiological aspects of rotavirus diarrhoea were studied in hospitalized children with acute diarrhoea in Lusaka, Zambia. Two hundred and fifty-six (24.0%) of 1069 children admitted to the study were shedding rotavirus. The rotavirus-positive rate was highest in children less than 1 year of age (37.0%) and it was also high in those less than 6 months old. Rotavirus diarrhoea was seen throughout the year with a higher rotavirus-positive rate in the dry season. In rotavirus-positive diarrhoea patients, more children were dehydrated (82.4%) than in the rotavirus-negative group (56.2%). Rotavirus infection was more common in the children with normal nutritional status (27.6%, 162/588) than in those with malnutrition (19.3%, 93/482). The associated case fatality rate in the rotavirus-positive group was 6.4%, significantly less than in the rotavirus-negative group (OR 0.44, 95% CI 0.24-0.79), and mortality cases were seen only in children less than 2 years old.

The impact of human immunodeficiency virus on mortality of patients treated for tuberculosis in a cohort study in Zambia

We have examined the impact of human immunodeficiency virus (HIV) on mortality of patients treated for tuberculosis in a prospective study in Lusaka, Zambia. Patients with sputum smear-positive, miliary, or meningeal tuberculosis were prescribed 2 months' daily streptomycin, thiacetazone, isoniazid, rifampicin, and pyrazinamide followed by 6 months thiacetazone and isoniazid; others, 2 months streptomycin, thiacetazone and isoniazid followed by 10 months thiacetazone and isoniazid. 239 patients (65 HIV-negative and 174 HIV-positive) were followed to 2 years from start of treatment. The crude mortality rate ratio for HIV-positive compared with HIV-negative patients over 2 years was 5.00 (95% confidence interval 2.30-10.86). Median survival for HIV-positive patients from the start of treatment was 22 months. At least 34% of HIV-positive patients for whom cause of death was known died from tuberculosis, three-quarters of these during the first month of treatment. Risk factors for death in HIV-positive patients included multi-site tuberculosis, history of prolonged diarrhoea or fever, oral thrush, splenomegaly, anergy to tuberculin, low weight, anaemia or lymphopenia, and poor compliance with regimens containing rifampicin and pyrazinamide. Tuberculosis, even treated, was a major cause of death in patients with HIV infection.

Intestinal secretory IgA immune response against human immunodeficiency virus among infected patients with acute and chronic diarrhea

Diarrhea is common in patients infected with the human immunodeficiency virus (HIV) in Africa. There has been speculation that HIV itself may cause some of the enteropathy seen. The intestinal secretory IgA (sIgA) response was used to evaluate HIV intestinal infections in Zambian patients with acute and chronic diarrhea. sIgA was extracted from stool specimens and evaluated by an ELISA. Seven (58%) of 12 HIV-positive patients with acute diarrhea and 25 (69%) of 36 HIV-positive patients with chronic diarrhea showed an sIgA response to HIV p24, compared with 1 of 10 HIV-positive patients without diarrhea (P < .025 for acute and P < .001 for chronic diarrhea). The mean duration of diarrhea was significantly longer in patients showing an anti-p24 response. An sIgA response to HIV antigens occurs commonly in infected patients with diarrhea and may provide further evidence of an etiologic role of HIV in the diarrhea associated with AIDS.

The impact of HIV on infectiousness of pulmonary tuberculosis: a community study in Zambia

OBJECTIVE

To examine the impact of HIV on infectiousness of pulmonary tuberculosis (TB).

DESIGN

A cross-sectional tuberculin survey carried out among household contacts of HIV-1-positive and negative patients with bacteriologically confirmed pulmonary TB. Contacts were also examined for active TB.

SETTING

Index cases were recruited from patients attending the University Teaching Hospital in Lusaka, Zambia and household contacts were examined during visits to their homes within Lusaka.

PATIENTS, PARTICIPANTS

A total of 207 contacts of 43 HIV-positive patients, and 141 contacts of 28 HIV-negative patients with pulmonary TB were examined.

MAIN OUTCOME MEASURES

Proportion of contacts of HIV-positive and negative index cases with a positive tuberculin response (diameter of induration > or = 5 mm to a dose of 2 tuberculin units).

RESULTS

Fifty-two per cent of contacts of HIV-positive pulmonary TB patients had a positive tuberculin response compared with 71% of contacts of HIV-negative patients (odds ratio, 0.43; 95% CI, 0.26-0.72; P < 0.001). This difference persisted after allowing for between-household variations in the tuberculin response. Tuberculin response in the contact was related to age of contact, intimacy with the index case and crowding in the household. However, the effect of HIV status of the index case was not confounded by these variables. Tuberculin response in the contact was also related to the number of bacilli seen in the sputum smear of the index case which partially explained the effect of HIV status of the index case. Active TB was diagnosed in 4% of contacts of HIV-positive and 3% of contacts of HIV-negative cases, respectively (P = 0.8).

CONCLUSIONS

HIV-positive patients with pulmonary TB may be less infectious than their HIV-negative counterparts and this may partly be explained by lower bacillary load in the sputum.

Negative sputum smear results in HIV-positive patients with pulmonary tuberculosis in Lusaka, Zambia

During recruitment to a prospective study of tuberculosis patients in Lusaka, Zambia, 109 had pulmonary disease proven by sputum culture for Mycobacterium tuberculosis, of whom 72 were HIV-1 antibody-positive and 37 were HIV-negative. Among these culture-proven cases, 43% of the HIV-positive patients had a negative sputum smear, compared with 24% of the HIV-negative cases. There was a strong trend towards lower grade or negative sputum smear in the HIV-positive group (P = 0.003). HIV-positive cases also had lower colony counts on culture and colonies took longer to appear. The findings imply that cases of HIV-associated pulmonary tuberculosis may frequently be missed and emphasise the need for new diagnostic methods.

The impact of human immunodeficiency virus on presentation and diagnosis of tuberculosis in a cohort study in Zambia

Two hundred and forty-nine patients with tuberculosis were recruited to a cohort study to investigate the interaction between tuberculosis and HIV in Lusaka, Zambia; findings at presentation are presented here. One hundred and eighty-two (73%; 95% confidence interval 67-79%) of the cases were HIV-1 antibody positive. The diagnosis of tuberculosis was confirmed by microscopy for acid-alcohol fast bacilli, culture of Mycobacterium tuberculosis, or histology in 74% of all cases. HIV negative and positive cases differed in site of disease: among HIV negative patients 72% had pulmonary disease alone, 16% extrapulmonary disease alone and 12% had both, whereas among HIV positive patients 40% had pulmonary disease alone, 34% extrapulmonary disease alone and 26% both (P < 0.001). HIV negative and positive cases were compared with regard to outcome of diagnostic procedures: 55% of HIV negative cases could be diagnosed at enrollment by sputum smear, but only 35% of HIV positive cases (P < 0.01). Among pulmonary cases confirmed by sputum culture, 76% of HIV negative patients had a positive sputum smear, compared with 57% of HIV positive patients (P = 0.09). Pleural and pericardial disease were difficult to confirm, but culture of pleural fluid was positive in 12/46 HIV positive patients, compared with 0/11 HIV negative patients. Lymph node disease was readily confirmed by biopsy. The tuberculin test was positive in only 30/110 (27%) of HIV positive cases, but in 21/38 (55%) of HIV negative cases (P < 0.01). Mycobacterium tuberculosis was cultured in 57% of HIV negative cases and 54% of HIV positive cases; no atypical mycobacteria were isolated. Initial resistance to isoniazid was present in isolates from 5% of cases with a positive culture.

Use of prednisolone in the treatment of HIV-positive tuberculosis patients

Corticosteroids are beneficial in the treatment of some forms of tuberculosis, but their role in TB affecting HIV-positive patients is not clear. During a cohort study of tuberculosis patients in Lusaka, Zambia, prednisolone was prescribed for specific indications. Six of 47 (13 per cent) of patients who received prednisolone early in treatment developed herpes zoster, compared with 2 of 118 (2 per cent) of those who did not. Three patients who received prednisolone developed Kaposi's sarcoma, compared with none who did not. At 2 months patients who had received prednisolone showed a greater improvement in generalized lymphadenopathy and cough. Controlled studies of the risks and benefits of administration of corticosteroids to HIV-positive TB patients are urgently needed.