Lymphocyte subset enumeration in HIV seronegative and HIV-1 seropositive adults in Dar es Salaam, Tanzania: determination of reference values in males and females and comparison of two flow cytometric methods.

The level of CD4(+) T-lymphocytes represents a useful marker with which to monitor the progression of HIV infection. Sex and geographical differences in the reference values of lymphocyte subsets have been reported. We have compared two flow cytometric methods (MultiSET and SimulSET) for the quantification of lymphocyte subsets using whole blood from 92 HIV seropositive and 241 seronegative adults, and determined the reference values of lymphocyte subsets in HIV seronegative Tanzanian subjects. In seronegative Tanzanian subjects, the percentages of CD3(+) and CD4(+) T-lymphocytes and the CD4(+):CD8(+) T-lymphocyte ratios were lower while the percentage of natural killer cells was higher compared to the levels of the corresponding parameters reported for Europeans. Seronegative Tanzanian females had significantly higher levels of CD3(+) and CD4(+) T-lymphocytes and CD4(+):CD8(+) T-lymphocyte ratios compared to seronegative males. The correlation coefficients of CD3(+), CD4(+) and CD8(+) T lymphocyte counts and percentages obtained by the two flow cytometric methods were high. The median values of the number of CD4(+) T-lymphocytes obtained by the two methods were not significantly different. In conclusion, determination of the reference values of lymphocyte subsets in HIV seronegative Tanzanian adults showed significant sex differences and differences in percentage values compared to those reported in certain other geographical areas. There was acceptable agreement in the levels of CD4(+) T-lymphocyte values obtained by the two flow cytometric methods.

Risk factors for syphilis among HIV-1 infected pregnant women in Dar es Salaam, Tanzania.

This study was conducted to determine the risk factors for recent (active) syphilis among HIV-1 seropositive pregnant women (N = 1058) in Dar es Salaam, Tanzania, Recruitment of study participants (N = 1058) was done between April 1995 and June 1997 at four main prenatal clinics in Dar es Salaam city. Study subjects were interviewed to obtain information about potential risk factors, and blood and genital specimens were collected for detection of syphilis and other genital infections. The prevalence of active syphilis was 5.9%. After adjusting for other risk factors, women without their own source of income had a 50% lower risk of syphilis (OR = 0.5, 95% CI: 0.3-0.9). The risk of active syphilis was significantly increased among women with genital ulceration on examination (OR = 8.4, 95% CI: 1.5-47.7), and in those with trichomoniasis (OR = 2.2, 95% CI: 1.2-3.8). HIV-related immunodeficiency was not associated with increased risk of syphilis. These results show that syphilis and other genital infections are a major problem among HIV infected women. Prevention of syphilis and other genital infections is urgently needed in this population.

Antimicrobial susceptibility pattern of Vibrio cholerae O1 strains during two cholera outbreaks in Dar es Salaam, Tanzania.

OBJECTIVE: To determine and compare the antimicrobial susceptibility patterns of Vibrio cholerae 01 strains, which were isolated in two cholera epidemics in 1997 and 1999 in Dar es Salaam. METHODS: V. cholerae 01 strains isolated from patients with cholera in Dar es Salaam city during 1997 (94 isolates) and 1999 (87 isolates) were stored on nutrient agar slants at room temperature and antimicrobial susceptibility pattern was determined, using Kirby Bauer method. SETTING: Department of Microbiology and Immunology, Muhimbili Medical Centre, Dar es Salaam, Tanzania. RESULTS: A total of 181 V. cholerae 01 strains were studied during two epidemic periods when tetracycline or erythromycin was used for treatment of patients with severe disease. Among the 94 V. cholerae 01 strains isolated in 1997; 98.6%, 93.6%, 83%, 81.9%, 36.2%, 35.5%, 3.2% were sensitive to ciprofloxacin, tetracycline, ampicillin, erythromycin, nalidixic acid, chloramphenicol and trimethoprim/sulphamethoxazole, respectively. Among the 87 V. cholerae 01 isolates collected in 1999, 100%, 58.6%, 46.0%, 46%, 47.1%, 19.5%, 3.4% were sensitive to ciprofloxacin, tetracycline, ampicillin, erythromycin, chloramphenicol, nalidixic acid and trimethoprim/sulphamethoxazole, respectively. Between 1997 and 1999, there was a significant increase in the proportion of V. cholerae 01 isolates resistant to tetracycline, ampicillin, nalidixic acid and to erythromycin but there was no change for susceptibility to ciprofloxacin and trimethoprim/sulphamethoxazole. CONCLUSION: Significant proportion of V. cholerae 01 strains in Dar es Salaam were resistant to commonly used antimicrobial agents during the two years of the study. Therefore, there is a great need to control the utilisation of antimicrobial agents in cholera control, in addition to continuing carrying out surveillance of antimicrobial resistance as a guide to choice of antimicrobial treatment. Rotational use of the available drugs with regular monitoring of susceptibility may contribute to continuing usefulness of such drugs.

Antimicrobial susceptibillty of Staphylococcus aureus strains at Muhimbili Medical Centre, Tanzania.

OBJECTIVE: To determine the antimicrobial susceptibility pattern of S. aureus isolates including the presence of methicillin resistant S. aureus strains. DESIGN: Cross-sectional study. SETTING: Department of Microbiology and Immunology, Muhimbili Medical Centre, Dar es Salaam, Tanzania between October 1997 and March 1998. PATIENTS: Two hundred and sixty patients consisting of 67 neonates, 114 children aged 18 years and below and 79 adults. MAIN OUTCOME MEASURES: Antimicrobial susceptibility to tetracycline, erythromycin, cefuroxime, methicillin and penicillin G and presence of mec A gene. RESULTS: Among the S. aureus strains, 97.3%, 68.1%, 37.3% and 6.5% were sensitive to cefuroxime, erythromycin, tetracycline and penicillin G respectively. Only one (0.4%) S. aureus isolate was resistant to methicillin using both the E test and presence of mec A gene. There was no significant difference between the sensitive S. aureus isolates from the neonates, children and adults. CONCLUSION: S. aureus strains are becoming more resistant to commonly used antimicrobial agents, the prevalence of methicillin resistant S. aureus strains in our study population is low compared with reported studies.

Immunological profile of endemic and epidemic Kaposi's sarcoma patients in Dar-es-Salaam, Tanzania.

Kaposi's sarcoma (KS) presents in four clinicopathological types namely classical/sporadic (CKS), endemic African (EKS), iatrogenic (IKS) and that associated with AIDS (AKS). Recently a putative herpes virus (HHV-8) was described and shown to be present in all four types of KS. The immunological status of patients with EKS has been conflicting. In this study total leucocyte counts, total lymphocyte counts and lymphocyte subsets of patients with EKS and AKS were determined by flow cytometry and compared to those of healthy HIV-1 seronegative controls. Results show that 50% of EKS lesions were of nodular type. Patients with EKS had significantly lower levels of CD4+ T- lymphocytes and CD4:CD8 ratio but significantly higher CD8+ T-lymphocytes compared to controls. Patients with AKS had significantly lower levels of CD4+ T-lymphocytes and also CD4:CD8 ratios but significantly higher percentage of CD8+ T-lymphocytes when compared with EKS patients. These findings indicate that in both forms of KS there is a certain degree of immunological disturbance which is more conspicuous in AKS because of HIV infection and suggests that HIV-1 acts synergistically with the aetiological agent (HHV-8) to cause a more aggressive type of KS.

Susceptibility pattern of uropathogenic gram negative bacilli to antimicrobial chemotherapeutic agents in a National Hospital in Dar es Salaam.

In a period of two months, 232 consecutive urinary tract pathogens were isolated from hospitalised and non-hospitalised patients. Among the isolates, 200 (86.2%) were gram negative bacilli, including E. coli 109 (54.5%), Klebsiella species, 44 (22.5%), Enterobacter species 19 (9.5%), Proteus species 18 (9%), Morganella morganii 9 (4.5%) and Salmonella typhimurium, one (0.5%). Antimicrobial susceptibility testing to amoxycillin/clavulanic acid, nitrofurantoin, gentamicin and cefuroxime was performed using Stoke's method. Among the 109 E. coli isolates, 107 (98.2%), 104 (94.5%), 105(95.5% and 107 (98.2%) were sensitive to amoxycillin/clavulanic acid, cefuroxime, nitrofurantoin and gentamicin, respectively. Of the 44 Klebsiella isolates, 42 (95.5%), 41 (95.5%), 40 (90.9%) and 34 (77.3%) were sensitive to amoxycillin/clavulanic acid, cefuroxime, nitrofurantoin and gentamicin, respectively. There was no significant difference when the suceptibility patterns of isolates from hospitalised patients were compared to those from outpatients. Although the susceptibility pattern of urinary tract pathogens to the commonly used antimicrobial agents in the hospital is still favourable, there is a need to establish strategies to prevent emergence of resistant bacterial strains.

Immunohaematological findings in healthy and HIV-1 infected adults in Dar es Salaam, Tanzania.

In order to assess the prognostic value of lymphocyte subsets and immune activation markers in HIV-1 infected Tanzanian patients, peripheral white blood cell(WBC) count, total lymphocytes, CD4+ and CD8+ T-lymphocytes and Beta-2 microglobulin (B-2M) concentrations were determined among healthy HIV-1 seronegative Tanzanian blood donors and in infected Tanzania individuals in different clinical stages of HIV-1 infection. CD4+ T-lymphocytes, CD8+ T-lymphocyte percentages, CD4:CD8 lymphocyte ratios and the concentrations of B-2M were strongly correlated with the clinical stages of HIV-1 infection. These results suggest that B-2M could be a useful prognostic marker in HIV-1 infection in settings where T-lymphocyte subset determinations cannot be done.

PIP: Lymphocyte subsets and concentrations of beta-2 microglobulin (B2M) were determined among 119 HIV-1 seronegative and 183 HIV-1 seropositive individuals at Muhimbili Medical Center (MMC) to assess their prognostic value in HIV-1 infected Tanzanian patients. The HIV-negative individuals were blood donors at MMC, while the HIV-positive participants were blood donors, patients admitted to one medical ward, and those seen at MMC's outpatient clinic who were found to be HIV-positive during the study period. HIV-negative blood donors were of mean age 28.8 years and patients were of mean age 33.5. The measurement of peripheral white blood cell (WBC) count, total lymphocytes, CD4 and CD8 T-lymphocytes, and B2M concentrations found CD4 T-lymphocytes, CD8 T-lymphocyte percentages, CD4:CD8 lymphocyte ratios, and the concentrations of B2M to be strongly correlated with the clinical stages of HIV-1 infection. These findings suggest that B2M could be a useful prognostic marker in HIV-1 infection in settings where T-lymphocyte subset determinations cannot be made.

Evaluation of the FACScount, TRAx CD4 and Dynabeads methods for CD4 lymphocyte determination.

A study to evaluate the performance of the FACScount, TRAx CD4 and Dynabeads methods for the determination of CD4+ T lymphocyte subset levels was conducted in Tanzania as part of a World Health Organization (WHO) collaborative multicenter field evaluation of alternative methodologies for the enumeration of CD4+ T lymphocytes. The objective was to compare the performance of these alternative methods in a developing country setting, against that of flow cytometry as the reference standard. T lymphocyte subset levels were determined in 91 HIV seronegative and 98 HIV-1 seropositive adults using the three alternative methods. CD4+ and CD8+ T lymphocyte counts were determined by all methods except for TRAx CD4 enzyme linked immunosorbent assay (ELISA) which measures CD4+ T lymphocyte levels only. Linear regression analysis was done to correlate the counts obtained by the alternative methods to those obtained by flow cytometry. The overall correlation coefficients of FACScount and Dynabeads CD4+ and CD8+ T lymphocyte counts with those of flow cytometry were high (r > 0.9). A lower correlation (r = 0.631) was obtained when TRAx CD4+ ELISA counts were compared to those of the reference method. These results show that two of these alternative methodologies are suitable for the determination of CD4+ and CD8+ T lymphocyte counts with the use of African blood samples. Since the methods are simpler and cheaper than flow cytometry, they provide an alternative option for the enumeration of T lymphocyte subsets in laboratories with limited facilities.

Response to podophyllotoxin treatment of genital warts in relation to HIV-1 infection among patients in Dar es Salaam, Tanzania.

Forty-two Tanzanian patients with genital warts were treated with 0.5% podophyllotoxin solution (Wartec) for 3 days. Thirteen patients (30.9%) were cured and a further 7 patients (16.7%) had more than 50% of lesions cleared at 6 weeks, while 19 patients were resistant to treatment. Three patients had a recurrence of lesions after an initial response. Thirty-three patients were tested for serological evidence of infection with human immunodeficiency virus (HIV) and 15 (45.5%) patients were shown to be HIV-1 antibody positive. The response to treatment was analysed in relation to HIV antibody status. The cure rate was significantly higher in HIV seronegative patients (8/18 = 44.4%) compared to HIV seropositive patients (1/15 = 6.7%) (P = 0.018). We conclude that podophyllotoxin treatment provides a useful non-hospital based treatment for genital warts, but HIV infection appears to contribute to the failure of treatment for genital warts.

Alternative confirmatory strategies in HIV-1 antibody testing.

Alternatives to confirmation of human immunodeficiency virus (HIV)-1 seropositivity by Western blot analysis were evaluated retrospectively using combinations of six anti-HIV-1 screening assays, including four enzyme-linked immunosorbent assays (ELISA) and two simple tests (a rapid dot immunoassay and an agglutination assay), according to an algorithm where sera are first screened by one assay and those repeatedly reactive on this assay are tested repeatedly by a second assay. Two panels of sera collected in Dar es Salaam, Tanzania, were used. Panel 1 was composed of 1,465 consecutive blood donor sera of which 99 (6.8%) were confirmed HIV-1 antibody positive, and panel 2 was composed of sera from 396 consecutively admitted patients at two medical wards of which 116 (29.3%) were confirmed HIV-1 antibody positive. Sera reactive on any of the six screening assays were also tested by a confirmatory Western blot assay. The sensitivity of the assays at the initial valid testing were as follows: Abbott 99.5%, Behring 99.5%, Organon 97.7%, Wellcozyme 100%, HIV CHEK-1 95.8%, and Serodia 95.8%. After repeat testing of sera that initially gave false-negative results all assays showed 100% sensitivity except HIV CHEK-1 (98.6%). The specificities after repeat testing were between 99.6 and 99.9% for all assays except for the Behring ELISA (98.1%). Several combinations of screening assays were found to give the same diagnostic accuracy as the screening assay followed by Western blot analysis. We conclude that an alternative confirmatory strategy can be fully satisfactory for some testing purposes.