Mood, cognition and serotonin transporter availability in current and former ecstasy (MDMA) users

RATIONALE

Chronic recreational ecstasy (MDMA) use has often been reported to be associated with psychopathology, memory impairments and serotonergic alterations. However, the findings have not been consistent.

OBJECTIVES

To attempt to replicate these findings, to investigate whether such alterations would be reversible and whether they could be predicted by parameters of previous drug use.

METHODS

In a cross-sectional design, 30 current and 31 ex-ecstasy users with ecstasy abstinence of at least 5 months, and 29 polydrug and 30 drug-naive controls were compared on measures of psychopathology, cognitive performance and serotonin transporter availability.

RESULTS

The groups did not differ significantly in age, gender distribution, education level and premorbid intelligence. The ecstasy groups did not differ significantly from polydrug controls on most of the relevant parameters of concomitant illegal drug use. Reported drug use was confirmed by hair and urine analyses. All three groups of drug users exhibited significantly elevated psychopathology compared with drug-naive controls. Only ex-ecstasy users were significantly impaired on verbal recall. Current ecstasy users showed significantly reduced distribution volume ratios of serotonin transporter availability in the mesencephalon and caudate nucleus. Regression analyses indicated that psychopathology and serotonergic alterations were best predicted by the number of ecstasy tablets taken on a typical event.

CONCLUSION

The results indicate that verbal memory impairments were possibly aggravated after prolonged ecstasy abstinence while there was tentative evidence of serotonergic recovery. On the other hand, self-reported elevated psychopathology appeared to be associated with polydrug use in general and not specifically with ecstasy use.

Preliminary genetic linkage map of Miscanthus sinensis with RAPD markers

We have used an "offspring cross" mapping strategy in combination with the random amplified polymorphic DNA (RAPD) assay to construct the first genetic map of the species Miscanthus sinensis (2 n = 2 x = 38). This map is based on an outbred population of 89 individuals resulting from the cross between two genotypes from a previously designed cross. Consequently, both parents are fullsibs. The same proportion of bi-parental markers (heterozygotic in both parents) and pseudo-testcross markers (heterozygotic in one parent and null in the other), mono-parental markers, have been obtained. A total of 383 RAPD markers were analysed within the 89 F1 plants. Out of these markers, 257 were mapped into 28 linkage groups which spanned a total map length of around 1,074.5 cM with an average density of 4.2 cM per marker. Out of 257 mapped markers, 62 were inherited from F1.1 (P1), 63 from F1.7 (P7) and 132 were bi-parental markers. The contribution to the map was equal from both parents. This map provides a useful tool for genetic analyses of agronomically interesting characters in M. sinensis such as flowering, yield, plant height, stem diameter and mineral constitution. The offspring cross mapping strategy is proposed to obtain a higher efficiency in developing integrated maps including both parents.

Severe lower respiratory tract infections associated with human parainfluenza viruses 1-3 in children infected and noninfected with HIV type 1

The aim of this study was to compare the clinical course of severe lower respiratory tract infections associated with human parainfluenza virus types 1-3 (HPIV 1-3) in hospitalised children infected with the human immunodeficiency virus type 1 (HIV-1) versus that in hospitalised children not infected with HIV-1. Children were enrolled prospectively as part of a broader study that evaluated the aetiology of lower respiratory tract infections in HIV-1-infected and -noninfected children from March 1997 through March 1999. HPIV types 1-3 were isolated from nasopharyngeal aspirate samples that were analysed using immunofluorescein monoclonal antibody assays. Thirty percent (24 of 80) of the children from whom HPIV was isolated were infected with HIV-1. Sixty-six percent (47 of 62) and 22% (14 of 62) of the HPIV isolates that were typed were subtypes 3 and 1, respectively. The clinical presentation of severe lower respiratory tract infection was similar in both HIV-1-infected and -noninfected children, except that the former were less likely to have wheezing (4.2% vs. 28.6%, P=0.01). Furthermore, the duration of hospitalisation was longer in HIV-1-infected children than in HIV-1-noninfected children (median 11.5 days [range 1-15 days] vs. median 7.5 days [range 1-22 days]; P=0.02), and mortality was higher (5 of 24 [20.8%] infected children vs. 0 of 56 noninfected children; P=0.001). Importantly, four of five (80%) of the HIV-1-infected children who died had other concurrent illnesses or predisposing factors for severe HPIV-associated disease. HPIV-associated lower respiratory tract infection causes greater morbidity and mortality in HIV-1-infected children than in HIV-1-noninfected children; however, this may be due to other concurrent illnesses in HIV-1-infected children.

Plasma concentrations of 5-HT, 5-HIAA, norepinephrine, epinephrine and dopamine in ecstasy users

Recreational use of the synthetic methamphetamine derivative MDMA (3,4-methylenedioxymethamphetamine), the main constituent of the illegal drug "ecstasy", has increased dramatically in recent years. The reasons for ecstasy-associated cardiovascular complications like tachycardia, arrhythmias and hypertensive crises and psychiatric symptoms like psychotic episodes are not well understood. We have measured the plasma concentrations of 5-HIAA, 5-HT, norepinephrine, epinephrine and dopamine in 159 ecstasy users and controls. Ecstasy users showed elevated resting sympathetic activity, reflected in increased norepinephrine, epinephrine and dopamine levels. The levels of these catecholamines correlated positively with the cumulative dose and also with consumption during the last 30 days and 12 months. Although it is known that significant changes in 5-HT and 5-HIAA appear in the cerebrospinal fluid in ecstasy users, we could not detect alterations in serotonergic neurotransmitters in plasma in this large sample of subjects. Thus, in the drug-free interval, ecstasy users show lowered central serotonergic activity (lowered 5-HT and 5-HIAA concentrations in CSF) along with unchanged central noradrenergic and dopaminergic activity (HVA and MHPG unchanged in CSF) and elevated peripheral noradrenergic, dopaminergic and adrenergic activity along with unchanged peripheral serotonergic activity (plasma levels). We conclude, that the data presented here could argue for a noradrenergic hyperreactivity in the drug-free interval in ecstasy users resulting from previous ecstasy consumption. Also for an association with psychotic episodes and cardiovascular complications like tachycardia, arrhythmias.

Specific neurotoxicity of chronic use of ecstasy

The use of the illicit drug ecstasy (mainly containing methylenedioxymethamphetamine, MDMA) is widespread among young people in western Nations. Animal experiments indicate that MDMA is a potent neurotoxin specifically affecting the serotonergic system. A few functional neuroimaging studies revealed central nervous alterations after the repeated use of ecstasy. We examined 94 ecstasy users in comparison to 27 control subjects by means of positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG). The FDG uptake rates were globally reduced in ecstasy users, most pronounced in the striatum. The uptake rates tended to be negatively correlated with the cumulative ecstasy doses. The results indicate that younger ecstasy users may be more vulnerable with regard to neurotoxicity.

Impact of human immunodeficiency virus type 1 infection on the epidemiology and outcome of bacterial meningitis in South African children

OBJECTIVE

To define the impact that the human immunodeficiency virus type 1 (HIV-1) epidemic has had on the burden and outcome of bacterial meningitis in an area with a high prevalence of pediatric HIV-1 infection.

METHODS

Children less than 12 years of age with proven or suspected bacterial meningitis were enrolled in this study between March 1997 and February 1999, and their hospital records were retrospectively reviewed for clinical data.

RESULTS

Sixty-two (42.2%) of the 147 children tested for HIV-1 infection were infected. Streptococcus pneumoniae (Pnc) exceeded Haemophilus influenzae type b (Hib) as the most important cause of meningitis in HIV-1-infected (74.2% vs. 12.9%, respectively) compared with uninfected children (29.4% vs. 42.3%, respectively, P less than 10(-5)). The estimated relative risk of Pnc meningitis was greater in HIV-1-infected than in uninfected children under 2 years of age (relative risk [RR] = 40.4; 95% confidence intervals [CI] = 17.7-92.2). Overall, HIV-1-infected children had a higher rate of mortality than uninfected children (30.6% vs. 11.8%, respectively, P = 0.01), and in particular, HIV-1-infected children with Pnc meningitis (60.8% vs. 36.0%, respectively, P = 0.04) had a poorer outcome.

CONCLUSIONS

Streptococcus pneumoniae has exceeded Hib as the most important pathogen causing bacterial meningitis in HIV-1-infected compared with uninfected children. Effective vaccination against Hib and Pnc should be evaluated to reduce the overall burden of bacterial meningitis in HIV-1-infected children.

Pim-1: a serine/threonine kinase with a role in cell survival, proliferation, differentiation and tumorigenesis

Pim-1 belongs to a family of serine/threonine protein kinases that are highly conserved through evolution in multicellular organisms. Originally identified from moloney murine leukemia virus (MuLV)-induced T-cell lymphomas in mice, Pim-1 kinase is involved in the control of cell growth, differentiation and apoptosis. Expression of Pim-1 kinase can be stimulated by a variety of growth factors and regulated at four different levels: transcriptional, post-transcriptional, translational and post-translational. Several signal transduction pathways may be associated with the regulation of Pim-1's expression; accumulating data support that the expression of Pim-1 protein is mediated through activation of JAK/STATs. Recent studies of Pim family kinases indicate that Pim-1 kinase plays important roles outside of the hematopoietic system as well.

The impact of the zona pellucida thickness variation of human embryos on pregnancy outcome in relation to suboptimal embryo development. A prospective randomized controlled study

BACKGROUND

The study represents a prospective randomized controlled study evaluating zona pellucida thickness variation (ZPTV) measurements versus conventional selection of embryos using classic embryo score criteria, prior to embryo transfer in human IVF/intracytoplasmatic sperm injection (ICSI).

METHODS

Eighty-six patients having > or =3 embryos, with a classic embryo score of < or =2.2, were allocated to either ZPTV measurement or classic embryo morphology score before embryo transfer. The technician selecting embryos using classic embryo scoring was not aware of the ZPTV measurement results. Of the embryos allocated to ZPTV measurements, only the embryos with the highest ZPTV were transferred.

RESULTS

We found no differences in the pregnancy rate per embryo transfer between the two groups (34.4 versus 35.7%). Neither did the implantation rates differ. However, significantly better results were obtained when ZPTV was used as the selection criteria in cases where all embryos had an asynchrony in development or a high embryo score (i.e. were of poorer quality) by classical evaluation (odds ratio = 2.51, confidence interval = 0.33-198).

CONCLUSIONS

Using a normally-developed embryo with an optimal embryo score, no beneficial effect of using ZPTV measurement was seen. However, when only less optimal embryos were available to select for transfer, ZPTV provided a x 2.5 increase in the chance of achieving a clinical pregnancy.

Long-term effects of 'ecstasy' abuse on the human brain studied by FDG PET

The popular recreational drug, 'ecstasy', mainly contains 3,4-methylenedioxymethamphetamine (MDMA) as the psychotropic agent. MDMA is suspected of causing neurotoxic lesions to the serotonergic system as demonstrated by animal studies, examinations of human cerebrospinal fluid, and the first positron emission tomography (PET) studies using the serotonin transporter ligand [11C]-McN5652. Damage of serotonergic afferents might mediate long-lasting alterations of cerebral glucose metabolism as a secondary effect. To study a relationship between ecstasy use and long-lasting alterations, PET using 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) was performed in 93 ecstasy users and 27 subjects without any known history of illicit-drug abuse. As an index of glucose metabolism, mean normalized FDG uptake was determined in both groups using a computerized brain atlas, and was compared for a selected number of brain regions. FDG uptake was normalized in each individual by dividing local FDG uptake by the maximum FDG uptake in the individual's brain. Within the group of ecstasy users we examined the relationship between FDG uptake and cumulative ecstasy dose, time since last ecstasy ingestion at the time of PET scanning, and age at first ecstasy use, respectively. Normalized FDG uptake was reduced within the striatum and amygdala of ecstasy users when compared to controls. No statistically significant correlation of the FDG uptake and the cumulative dose of ecstasy was detected. A positive correlation was found in the cingulate between FDG uptake and the time since last ecstasy ingestion. As compared to the control group, normalized FDG uptake in the cingulate was reduced in ecstasy users who took ecstasy during the last 6 months, while it was elevated in former ecstasy users who did not consume ecstasy for more than 1 year. FDG uptake was significantly more affected in ecstasy users who started to consume ecstasy before the age of 18 years. In conclusion, ecstasy abuse causes long-lasting effects on glucose metabolism in the human brain. These effects are more severe in the case of very early abuse. However, several questions still remain to be answered, i.e. the correlation of the neuronal alterations and the history of ecstasy use (cumulative dose, and time since the last dose) and its reversibility.

Preparing to meet foreign bugs. Travel, immigration, and international adoptions require special precautions

As the world's population becomes increasingly mobile, children are more likely to be exposed to exotic and troublesome pathogens. These exposures raise concerns about protecting not only kids but the general population as well. In this article, Dr Petersen presents ways to avoid illness in children who travel to other parts of the world. She also discusses concerns about communicable disease as it relates to immigration or adoption of foreign-born children, especially those from developing nations.

Orofacial findings in the Klippel-Trénaunay syndrome

The Klippel-Trénaunay syndrome is a triad of congenital anomalies characterised by haemangiomas, varicosities, and unilateral bony and soft tissue hypertrophy. Hypertrophy usually affects one distal limb, but trunk or face may be affected. Cutaneous haemangiomas (nevus flammeus) of varying extent and irregular contour are often present in the hypertrophic regions. Varicosities may also be part of the vascular lesions of the syndrome. Orofacial manifestations include facial asymmetry, jaw enlargement, and malocclusions as well as premature tooth eruption. Two cases of the Klippel-Trénaunay syndrome are presented here. Both of these show the typical hemifacial hypertrophy and premature eruption of teeth on the affected side. In the first case only the left mandibular region was affected. In contrast, in the second there was hypertrophy of the whole left side of the body including upper and lower jaws. This boy also suffers from congenital ideokinetic retardation, while the first was otherwise normal. Both cases differ from previously reported cases of the Klippel-Trénaunay syndrome in lacking any prominent facial nevus flammeus. In the first case there was also malformation of the crown of the first permanent molar on the affected side that has not been described previously.

Pregnancy rates in relation to time intervals between repeat sperm-retrieval procedures

A total of 76 repeat sperm retrievals were carried out in 47 azoospermic men. The outcome of the procedures was evaluated regarding to the interval between two successive procedures. Sperm motility and pregnancy rate were not increased by increasing the interval between two successive sperm retrievals from less than 90 days to more than 180 days. The pregnancy rate declined from 50% with a less than 90-day interval to 25% with a more than 180-day interval. The trend did not quite reach the significance level. Pregnancy was obtained in only 27% of the couples where TESE was done the last time against 48 and 57% where PESA and TESA, respectively, were performed the last time (p < .05). This study suggests that sperm retrieval procedures in men with obstructive azoospermia can be carried out with time intervals of only 3 months to obtain an optimal pregnancy rate, and it might suggest that an epididymal aspiration procedure should be preferred for a TESE.

Molecular approach to the characterisation of fungal communities: methods for DNA extraction, PCR amplification and DGGE analysis of painted art objects

A protocol for efficient extraction of fungal DNA from micromycetes colonising painted art objects was developed. Polymerase chain reaction (PCR) inhibitors were successfully removed by a combined application of a Chelex-100 adsorption resin and a Geneclean Kit for Ancient DNA. Universal fungal primers for PCR amplification of 28S rDNA (U1 and U2) were tested for their applicability in denaturing gradient gel electrophoresis (DGGE) analysis of fungal communities. Artificially produced mortar samples inoculated with fungal pure cultures isolated from mural paintings were used as model objects for DNA extractions and DGGE analysis. Good resolution in DGGE was achieved using 260-bp rDNA fragments amplified with U1/DGGE and U2 primers directly from model communities.

Embryo quality and developmental potential is compromised by age

AIMS

The aim of this retrospective study was to assess whether and how the age of the woman affects the quality and developmental potential of the oocytes and embryos in an ART program.

METHOD AND MATERIAL

A total of 878 IVF cycles was included as a consecutive series of single transfers (n=292), dual transfers (n=366) and triple transfers (n=220), where all the transferred embryos in each cycle were of identical quality score and identical cleavage stage.

RESULTS

We found a highly significant decrease in oocyte recovery with increasing age with about one oocyte per 2.3 years (95% CI 1.8 years to 3.1 years, p<0.0001). Further, we found that the number of oocytes that cleaved declined significantly with increasing age with one per 3.7 years (95% CI 2.7 years to 5.5 years, p<0.0001). This decline was mainly due to the decline in number of oocytes retrieved as the ratio of aspirated oocytes that cleaved with increasing age (approx. -0.04/10 year 95% CI: -0.10; +0.009) was not significantly different (p=0.10). The percentage of transfers using fragmented embryos did not increase significantly with increasing age (p=0.08). The odds of fragmentation increased by 3% per year. The average number of embryos transferred decreased significantly (p=0.03) with age from approximately 2.1 at the age of 25 to approximately 1.8 at the age of 40. In a selected subgroup of embryos all consisting of good quality embryos, a significant decrease was found in implantation rate with increasing age (approx. -0.08/10 years, 95% CI: -1.6; +0.00, p=0.05). Of the 357 pregnancies achieved in this study we found a significantly decreased ongoing pregnancy rate and a significantly increased abortion rate with increasing age (p=0.03). The decrease in the rate of ongoing pregnancies was almost linear, decreasing by approximately 1.5% per year.

CONCLUSIONS

We conclude that age has an impact throughout a woman's reproductive life and that it is important to realize that the age-related decline in fertility may start already in the late twenties and not in the mid-thirties as is generally assumed.

cDNA cloning, sequencing and characterization of bovine pim-1

The cDNA clone of bovine pim-1 has been isolated from phorbol-12-myristate-13-acetate (PMA) and concanavalin A (ConA)-activated peripheral blood lymphocytes (PBLs). The full-length cDNA contains a 411bp 5' untranslated region (5'-UTR), followed by a 939bp coding region and a 3' untranslated region (3'-UTR) that contains 1403bp. Comparison of the bovine pim-1 coding sequence with the human, rat, mouse, frog and zebrafish counterparts reveals 94, 90, 89, 67 and 40% homology at the nucleotide level, respectively. The predicted amino acid sequence of bovine Pim-1 shares 98.7, 97.1, 93.3, 68.8, and 52.4% similarity with the sequences of human, rat, mouse, frog, and zebrafish, respectively. The 5'-UTR of bovine pim-1 shares high sequence similarity to the human and mouse counterparts and is G/C-rich (75%) which may promote a high degree of secondary structure. The 3'-UTR of bovine pim-1 contains two potential polyadenylation sites and an A/T-rich motif which has been shown to decrease the stability of polyA mRNA molecules. Southern blot results indicate that a single copy of the gene exists in the bovine genome. Northern blot results show that PMA stimulation of PBLs increases the expression of the pim-1 mRNA. In addition, examination of Pim-1 protein expression in PBLs stimulated with a variety of mitogens including ConA, PMA, anti-CD3 and purified protein derivative (PPD) from Mycobacterium tuberculosis, reveals two different types of expression patterns during the course of a 24h period of stimulation. ConA and PPD gave a biphasic pattern of expression while PMA and anti-CD3 gave single transient pattern of expression suggesting that expression is controlled by more than one signaling pathway.

Impact of human immunodeficiency virus type 1 on the disease spectrum of Streptococcus pneumoniae in South African children

BACKGROUND

HIV-infected children are at increased risk of developing invasive Streptococcus pneumoniae disease.

OBJECTIVE

To determine the impact of the HIV epidemic on the epidemiology of invasive pneumococcal disease in hospitalized African children.

METHODS

Children <12 years of age with invasive pneumococcal disease were enrolled between March, 1997, and February, 1999.

RESULTS

The seroprevalence of HIV was 64.9% (146 of 225). In children with pneumococcal isolates from serogroups 6, 9, 14, 19 or 23 (pediatric serogroups), pneumonia and pneumonia with concurrent meningitis was more common in HIV-infected children (P = 0.03 and P = 0.003, respectively), whereas septic shock occurred more often in HIV-uninfected children (P = 0.0003). The overall burden of severe invasive pneumococcal disease was 41.7 (95% confidence interval, 26.5 to 65.6) fold increased in HIV-infected compared with HIV-uninfected children. Reduced susceptibility to penicillin (45.91% vs. 27.9%, P = 0.009), trimethoprim-sulfamethoxazole (44.5% vs. 19.0%, P = 0.0002) and multiple drug resistance was more common in HIV-infected than in HIV-uninfected children (24.0% vs. 6.4%, P = 0.01), respectively. The increased burden of disease and reduced antibiotic susceptibility of pneumococcal isolates in HIV-infected children was because of a heightened susceptibility to disease caused by pediatric serogroups in these children than in HIV-uninfected children (P = 0.01). Although the case fatality rates did not differ between HIV-infected and -uninfected children, mortality in HIV-infected children with advanced AIDS (Stage C, 22 of 61; 36.1%) was greater than that in children with moderate AIDS (Stage B, 12 of 85; 14.1%, P = 0.002).

CONCLUSIONS

In children with invasive pneumococcal disease caused by the pediatric serogroups, HIV-infected children have more antibiotic-resistant isolates and have a different clinical presentation than do HIV-uninfected children.

Effects of leptin on basal and FSH stimulated steroidogenesis in human granulosa luteal cells

BACKGROUND

Body weight influences fertility and studies in mice have indicated that leptin is one of the mediators of this effect. Leptin is believed to centrally stimulate the hypothalamic-pituitary axis resulting in increased gonadotropin release. Moreover, leptin is present in follicular fluid and the receptor is expressed in the human ovary. The aim of this study was to evaluate the direct effect of leptin on cultured human granulosa cell steroidogenesis.

METHODS

Granulosa cells were obtained in connection with IVF procedures, and then cultured in a serum-free medium containing androstenedione (1 microM) for a total of 4 days. After 2 days of culture the medium was changed and the hormones under study were added. We tested the effect of leptin (1, 20, 100 ng/ml) on basal, FSH (10-100 ng/ml), and FSH (10-100 ng/ml)+IGF-I (30 ng/ml) stimulated steroidogenesis.

RESULTS

Leptin (20 ng/ml and 100 ng/ml) significantly reduced basal and FSH-stimulated estradiol secretion (p<0.05). Basal and FSH (10 and 30 ng/ml) stimulated progesterone production was significantly inhibited by leptin 20 ng/ml, whereas leptin 100 ng/ml significantly reduced basal but not FSH stimulated progesterone production. Finally, steroidogenesis stimulated by IGF-I alone and in combination with FSH was not influenced by leptin.

CONCLUSION

These results suggest that leptin acts directly to inhibit basal and FSH stimulated estradiol and progesterone production in cultured human granulosa cells. This raises the possibility that high circulating leptin levels as seen in obese women may compromise fertility through peripheral mechanisms.

Influence of zona pellucida thickness of human embryos on clinical pregnancy outcome following in vitro fertilization treatment

PURPOSE

To evaluate the correlation between the degree of zona pellucida thickness variation (ZPTV) of transferred embryos with identical morphologies and subsequent clinical pregnancy rates during 141 intracytoplasmic sperm injection (ICSI) treatment cycles.

METHODS

A total of 141 women participating in the study group comprising mostly male factor infertilities and some repeat in vitro fertilization (IVF) failures were transferred, 2 days after ovum pickup, with two to three embryos with identical grades created by fertilization with ICSI. All selected embryos were subjected to zona pellucida thickness measurements immediately prior to transfer using a computerized embryo measurement program from videocinematography recordings.

RESULTS

A total of 326 identical-grade transferred pre-embryos resulted in 70 clinical pregnancies with live-born implantation rate of 27.6%. A highly significant correlation was observed between ZPTV of transferred embryos and the IVF outcome with 77.1% and 83.64% of the clinical pregnancies resulting from transferred embryos with ZPTV values greater than 20 and 25, respectively. The mean ZPTV values for 70 conceptual cycles and 62 nonconceptual cycles were 28 +/- 6.43 and 17.85 +/- 8.11, respectively. No significant correlation between ZP thickness and number of blastomeres in the transferred embryos was evident, though embryos with better scores had significantly thinner zonae and higher ZPTV values. Though average zona thickness of embryos declined with age, the mean ZPTV value for women less than 30 years old was significantly higher (25.84 +/- 8.57) as compared with those from women older than 35 years (20.72 +/- 8.45).

CONCLUSIONS

The degree of ZPTV of the transferred embryos exhibits a strong correlation with clinical pregnancy outcome following IVF treatment. This potentially reliable indicator of IVF success rate could be used as a criteria for embryo selection during clinical transfers.

Increased disease burden and antibiotic resistance of bacteria causing severe community-acquired lower respiratory tract infections in human immunodeficiency virus type 1-infected children

To improve the management of lower respiratory tract infections (LRTI) in human immunodeficiency virus type 1 (HIV-1)-infected children, we assessed the burden of disease, clinical outcome and antibiotic susceptibility of bacteria causing severe community-acquired LRTI in children. A prospective, descriptive study was performed in the pediatric wards at a secondary and tertiary care hospital in South Africa. Urban black children aged 2-60 months admitted with severe acute LRTI from March 1997 through February 1998 were enrolled. HIV-1 infection was present in 45.1% of 1215 cases of severe LRTI. Bacteremia occurred in 14.9% of HIV-1-infected and in 6.5% of HIV-1-uninfected children (P<.00001). The estimated relative incidence of bacteremic severe LRTI in children aged from 2 to 24 months were greater in HIV-1-infected than in -uninfected children for Streptococcus pneumoniae (risk ratio [RR], 42.9; 95% confidence interval [CI], 20.7-90.2), Haemophilus influenzae type b (RR, 21.4; 95% CI, 9.4-48.4), Staphylococcus aureus (RR, 97.9; 95% CI, 11.4-838.2) and Escherichia coli (RR, 49.0; 95% CI, 15.4-156). Isolation of Mycobacterium tuberculosis was also more common in HIV-1-infected than in -uninfected children (RR, 22.5; 95% CI, 13.4-37.6). In HIV-1-infected children, 60% of S. aureus and 85.7% of E. coli isolates were resistant to methicillin and trimethoprim-sulfamethoxazole, respectively. The case-fatality rates among HIV-1-infected children was 13.1%, and among HIV-1-uninfected children, 2.1% (adjusted odds ratio [AOR]; 6.52, 95% CI, 3.53-12.05; P<.00001). The changing spectrum of bacteria and antibiotic susceptibility patterns in HIV-1-infected children requires a reevaluation of the empirical treatment of community-acquired severe LRTI in children from developing countries with a high prevalence of childhood HIV-1 infection.