Centers For Disease Control Group Research Articles

Cellular fatty acid composition of Lautropia mirabilis.

Ten strains of Lautropia mirabilis (ATCC 51599(T) and nine phenotypically similar clinical isolates) were examined for cellular fatty acid (CFA) composition to evaluate their chemical relatedness to known bacterial species and groups. The CFAs were liberated from whole cells by base hydrolysis, methylated, and analyzed by gas-liquid chromatography. CFA profiles were generated by using a commericial software package (MIDI, Newark, Del.). All strains tested had an identical CFA profile characterized by major amounts of 16:1omega7c (41%) and 16:0 (44%); smaller amounts (1 to 4%) of 3-OH-10:0, 12:0, 14:0, 15:0, and 18:1 omega7c; trace amounts (<1%) of 10:0, 18:2 and 18:0; and no cyclopropane acids. This profile was similar to the CFA profiles of Acidovorax delafieldii, Comamonas terrigena, and strains of an unclassified Centers for Disease Control group designated weak oxidizer group 1. CFA analysis, when supplemented by phenotypic characterization, is useful for the identification of L. mirabilis isolates.

Dysgonomonas gen. nov. to accommodate Dysgonomonas gadei sp. nov., an organism isolated from a human gall bladder, and Dysgonomonas capnocytophagoides (formerly CDC group DF-3).

Results of a polyphasic taxonomic study on an unknown Gram-negative, facultatively anaerobic, coccobacillus-shaped organism isolated from an infected human gall bladder are presented. Phenotypic and molecular taxonomic studies revealed the organism to be close to, but distinct from, organisms designated CDC (Centers for Disease Control and Prevention) group DF-3. The unknown bacterium was readily distinguished from reference strains of Bacteroides, Prevotella, Porphyromonas and related taxa by 16S rRNA gene sequencing, biochemical tests, analysis of cellular long-chain fatty acids and electrophoretic analysis of whole-cell proteins. Based on the results of the present study, it is proposed that the unknown bacterium be classified in a new genus, Dysgonomonas, as Dysgonomonas gadei sp. nov. (type strain CCUG 42882T = CIP 106420T). In addition, a new species, Dysgonomonas capnocytophagoides sp. nov., is proposed to accommodate strains previously belonging to CDC group DF-3. The type species of the genus Dysgonomonas is Dysgonomonas gadei.

Assignment of Centers for Disease Control group IVc-2 to the genus Ralstonia as Ralstonia paucula sp. nov.

An integrated genotypic and phenotypic analysis of 12 Centers for Disease Control (CDC) group IVc-2 strains revealed that this taxon represents a novel species belonging to the genus Ralstonia. Comparative 16S rDNA sequence analysis allocated a representative CDC group IVc-2 strain to the Ralstonia branch of the beta subclass of the Proteobacteria. DNA-DNA hybridizations did not detect significant binding levels towards any presently known Ralstonia species, including Ralstonia pickettii. Its DNA base ratio is between 65 and 67 mol%. The name Ralstonia paucula sp. nov. is proposed, with strain LMG 3244 (= CDC E6793), isolated from a human respiratory tract, as the type strain. R. paucula can be differentiated from other Ralstonia species by whole-cell protein analysis, amplified rDNA restriction analysis and a variety of classical biochemical tests. Strains have been isolated from various human clinical and environmental sources.

Anorectal surgery in patients infected with human immunodeficiency virus: factors associated with delayed wound healing.

A review of all anorectal operations in patients infected with human immunodeficiency virus (HIV) was performed to assess the incidence, variety, and clinical course of anorectal disease in these patients and to identify factors influencing wound healing. Anorectal disease is the most common indication for surgical intervention in patients infected with HIV. The cause and management of HIV-related anorectal conditions, which differ significantly from non-HIV-related diseases, are not clear. There also is considerable variation in the reported results of surgical procedures, including wound healing. St. Vincent's Hospital, Sydney, is situated in an area with the highest concentration of individuals infected with HIV in Australia. The medical records of all identified patients infected with HIV who had an anorectal operation at St. Vincent's General Hospital between January 1, 1988, and January 31, 1995, were reviewed retrospectively. Logistic regression, Mann-Whitney U test, and Fisher's exact tests were used for analysis. One thousand five hundred two patients with acquired immune deficiency syndrome (AIDS), equivalent to 26.8% of all known patients with AIDS in Australia at this time, were admitted to this hospital during the 7-year period. One hundred one patients infected with HIV underwent 161 anorectal operations. All patients were male homosexuals (98 patients, 97%) or bisexuals (3 patients, 3%), with intravenous drug use an additional risk factor in 5 patients (5%). Thirty-seven percent of patients had more than one operation. Seventy-two percent of patients were Centers for Disease Control (CDC) group 4 (AIDS) at operation, 27% were group 2, 1% was group 3, and none were group 1. Accurate information about wound healing was available for 74% of first operations, and univariate and multivariate logistic analyses of these showed that when the CD4+ T-lymphocyte count was <50 cells/ microL, healing was significantly retarded (p = 0.016). The Centers for Disease Control group, patient age, and serum albumin were not significant predictors of wound healing. The interval between HIV diagnosis and operation was not associated with impaired wound healing, but recognition of AIDS more than 1 year before operation was associated with significantly better wound healing compared with those in whom AIDS developed within the year before operation (p = 0.025). In the patients for whom accurate wound healing information was available, only 40% had healed their wounds by 3 months after operation. Wound healing was worst for patients with chronic fissures, only 16% of whom had healed their wounds at 3 months. The wound healing rate was worse for repeat operations than for first operations. Ten percent of patients had anorectal malignancies, none of which were diagnosed clinically before or during operation. Wound healing is a significant problem after anorectal operations in patients infected with HIV, especially when the CD4 count is <50/microL. Although there seems to be little or no benefit from more invasive operations in some cases, thorough examination with adequate biopsies is required in all cases. The best management of anorectal disease in patients infected with HIV still is unclear.

Anal cytological abnormalities and anal HPV infection in men with Centers for Disease Control group IV HIV disease.

OBJECTIVE: To characterise risk factors for abnormal and cytology and anal human papilloma virus (HPV) infection in homosexual/bisexual men with advanced HIV related immunosuppression. DESIGN: Cross sectional study of men...

Inadequate erythropoietin response to anaemia in HIV patients: relationship to serum levels of tumour necrosis factor-alpha, interleukin-6 and their soluble receptors.

Severe anaemia is a frequent complication in advanced HIV infection. In our study we investigated the interaction between cytokine network, HIV infection and erythropoietin (Epo) response with increasing anaemia levels. No correlations could be established between circulating tumour necrosis factor (TNF)-alpha and any of the examined parameters. However, a negative correlation was found between haemoglobin values and soluble TNF receptor levels (sTNF-R-I: r = -0.54; P < 0.001; sTNF-R II: r = -0.47; P < 0.001) as well as interleukin-6 levels (r = -0.29; P < 0.01). In contrast, no significant increase in log[Epo], counterbalancing haemoglobin decline and paralleling the rise in sTNF receptors, was found. In patients classified as stage III, according to the Centers for Disease Control (CDC) classification, the erythropoietin response was significantly more impaired than in patients from CDC groups I and II (P < 0.01). The results of this study suggest that similar to its action in vitro, activation of the TNF/TNF-R system may impair erythropoietin production in HIV-associated anaemia. Due to the brief half-life of TNF-alpha, this activation is particularly reflected by elevations of soluble TNF receptor levels.

Polyphasic analysis of strains of the genus Capnocytophaga and Centers for Disease Control group DF-3.

A polyphasic approach was used to determine the relationships between well-characterized reference strains representing all seven Capnocytophaga species. One Centers for Disease Control (CDC) group DF-3 strain, a presumed relative of the genus Capnocytophaga, and 15 field isolates were included as well. Fourteen isolates were assigned to named Capnocytophaga species, all of which could be differentiated by means of whole-organism protein electrophoresis. A separate position was occupied by the CDC group DF-3 strain and by one field isolate representing a novel Capnocytophaga species. The phylogenetic position of each taxon was determined by means of 16S rRNA sequence analysis. A considerable genotypic heterogeneity within the genus Capnocytophaga was detected in spite of the minimal phenotypic differences. Comparative 16S rRNA sequence analysis revealed that CDC group DF-3 is not a close relative of the capnocytophagas but constitutes a separate genus that clusters together with Bacteroides forsythus and Bacteroides distasonis, two generically misclassified Bacteroides species. The degree of protein similarity correlated with our and published DNA-DNA binding values. Percentage 16S rRNA similarity values of greater than 97% did not guarantee conspecificity. All Capnocytophaga strains had very similar fatty acid contents characterized by significant amounts of 14:0, 15:0 iso (greater than 55%), 16:0, 16:0 3OH, and 17:0 iso 3OH. PCR-mediated DNA fingerprinting allowed discrimination of most species, although some strains could not be classified efficiently because of DNA polymorphisms.

Circulating levels of mannose binding protein in human immunodeficiency virus infection

Mannose binding protein (MBP) is a serum lectin which, upon binding to a carbohydrate extremity, acquires the ability to activate the classical complement pathway. MBP binds human immunodeficiency virus (HIV) in vitro via glycans on gp120 and thus, it may play a defensive role in HIV infection and contribute to virus clearance through the activation of complement associated with this condition. We measured serum MBP and activation indices of the classical complement pathway (plasma C4d and C3d) in HIV-seropositive patients at different stages of disease severity, and in normal subjects. MBP was higher in HIV patients as a whole and in each Centers for Disease Control (CDC) group than controls (P<0.01). MBP was not significantly different between CDC groups and and did not significantly correlate either with CD4-positive lymphocytes, neopterin or beta2-microglobulin or with C4d and C3d. The possibility that MBP plays a defensive role in HIV infection cannot be excluded, but, it it is, it does not appear to act by recruiting complement for vital elimination.

Serum Levels of Stem Cell Factor Are Increased in Asymptomatic Human Immunodeficiency Virus-Infected Patients and Are Associated With Prolonged Survival

Cytopenia is a common complication of human immunodeficiency virus (HIV) infection and can affect different hematopoietic lineages, including erythropoiesis, lymphopoiesis, thrombopoiesis, and granulopoiesis. Stem cell factor (SCF), a cytokine expressed by bone marrow stromal cells, is a multipotential growth factor acting on early progenitor cells of most hematopoietic lineages. Therefore, we investigated the serum SCF levels in 74 HIV-infected persons without active secondary infection at different stages of HIV infection [Centers for Disease Control (CDC) stages A through C]. Circulating SCF levels were determined by enzyme-linked immunosorbent assay and were found to be significantly elevated in CDC stage A as compared with normal controls (7.18 +/- 1.94 ng/mL v 3.95 +/- 0.91 ng/mL, P = .04). However, in CDC groups B and C, SCF levels were lower than in CDC group A (3.29 +/- 0.75, P = .162, and 1.95 +/- 0.39, P = .005, respectively). Serum levels greater than 1.8 ng/mL were associated with a longer survival (P = .0037) in 74 HIV type 1 (HIV-1)-seropositive patients monitored for up to 114 weeks, suggesting that this cytokine may be directly associated with the disease course. A Cox proportional hazards model showed SCF to be an independent prognostic factor for survival (risk ratio for death, 0.73; 95% confidence interval, 0.56 to 0.95; P = .019). Serum SCF levels decreased on follow up in 24 of 38 patients or remained below 0.4 ng/mL in 10 of 38 patients from whom a second blood sample was collected after a mean interval of 44 weeks. To determine potential regulatory factors of SCF expression by stromal cells, we exposed cultured fibroblasts to various cytokines. Only interleukin-4 (IL-4) upregulated SCF mRNA. As IL-4 is modulated during early HIV disease, it may be a key regulator of SCF secretion. Further studies are required to elucidate the mechanism of SCF action and regulation in patients with HIV infection.

Relationship between the tumour-associated antigen 90K and cytokines in the circulation of persons infected with human immunodeficiency virus

A tumour-associated antigen known as 90K has been found in high concentrations in the serum of patients infected with human immunodeficiency virus (HIV) even in the absence of neoplastic complications. In order to investigate the relationship between the production of 90K and soluble inflammatory mediators, we studied serum concentrations of the antigen, tumour necrosis factor-alpha (TNF-alpha), interleukin-I-alpha (IL-I-alpha), interferon-gamma (IFN-gamma), IFN-alpha, neopterin and beta 2-microglobulin (beta 2-m) in patients with non-neoplastic HIV infection at various stages of disease and in control persons. The antigen was detected in all those studied but its concentration was higher in HIV-infected patients compared with controls (P < 0.001), increasing progressively with advancing stages of disease. There was a negative correlation between concentrations of 90K and IL-I-alpha in patients in U.S.A. Centers for Disease Control groups II and III (P < 0.02) and also between that of 90K and both TNF-alpha (P < 0.01) and IL-I-alpha (P < 0.05) in control persons. The results indicate that 90K is not merely a tumour-associated antigen and that its production may be part of immune and inflammatory responses in the absence of neoplasia. The correlation between the concentrations of 90K and of some cytokines in asymptomatic patients and healthy persons suggests that 90K may be part of a network of immune and inflammatory reactants.

Plasma concentration of cytokine antagonists in patients with HIV infection.

There is increasing evidence that cytokines contribute to the immunopathogenesis of human immunodeficiency virus (HIV) infection. It may be, therefore, that compensatory rises in circulating cytokine antagonists also occur in HIV infection and that such changes mark disease progression. To test this idea, plasma concentrations of the cytokine antagonists alpha-melanocyte-stimulating hormone (alpha-MSH), interleukin-1 receptor antagonist (IL-1ra), and soluble tumor necrosis factor receptor (sTNFr) were measured in patients of different Centers for Disease Control (CDC) categories of HIV infection and in seronegative controls. Plasma levels of all these cytokine antagonists were higher in HIV-infected patients. IL-1ra and sTNFr concentrations were correlated with indicators of disease activity: positively with plasma neopterin and negatively with CD4+ T lymphocyte counts. alpha-MSH and sTNF r were greater in CDC groups III and IV, whereas IL-1ra was elevated only in the latter group. Because cytokines activate the hypothalamic-pituitary-adrenal axis and adrenal steroids inhibit cytokine production, we measured circulating adrenocorticotropic hormone (ACTH) and cortisol in HIV-infected patients and investigated relations among these hormones, cytokine antagonists, and markers of disease progression. It appears that these physiological modulators of cytokine activity are not closely linked to sTNFr, IL-1ra and alpha-MSH: there were no significant correlations between plasma concentrations of ACTH or cortisol and those of cytokine antagonists, nor were there correlations between hormones and markers of disease progression such as neopterin or CD4+ T cell counts. It is notable that severe adrenal insufficiency was extremely rare (3%) in HIV-infected patients; it was confined to the AIDS group and was consistently secondary to ACTH deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Neisseria weaveri sp. nov. (formerly CDC Group M-5), from Dog Bite Wounds of Humans

The taxonomic relationships of strains belonging to Centers for Disease Control group M-5 were examined. Previous studies of rRNA cistron similarities placed this organism on the Neisseriaceae rRNA branch of rRNA superfamily III; the closest neighbors included the genus Neisseria and groups EF-4a and EF-4b. The group M-5 strains were characterized by a range of phenotypic tests, and their G + C contents and DNA-DNA relatedness levels were determined. In addition, a numerical taxonomic analysis of the whole-cell protein patterns (obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) of group M-5 and related taxa was performed. The strains studied included 45 group M-5 strains, the type strains of six Neisseria species or subspecies, three group EF-4a reference strains, and three group EF-4b reference strains plus the type strain of the phenotypically similar organism Oligella urethralis. Our results showed that the group M-5 strains were members of a homogeneous taxon distinct from phylogenetically closely related taxa. The genomic divergence as revealed by levels of rRNA cistron similarity and phenotypic characteristics indicate that group M-5 can be considered a new species of the genus Neisseria. We therefore propose the new species Neisseria weaveri, with NCTC 12742 (= CCUG 4007 = ISL775/91 = LMG 5135) as the type strain. N. weaveri strains are strictly aerobic, gram-negative, nonmotile, rod-shaped organisms which are catalase and oxidase positive, nonsaccharolytic, and able to grow on MacConkey agar and do not reduce nitrate but generally reduce nitrite.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of Centers for Disease Control group NO-1, a fastidious, nonoxidative, gram-negative organism associated with dog and cat bites

Seventeen strains of fastidious, nonoxidative, gram-negative rods, isolated from human wounds resulting primarily from dog or cat bites, formed a distinct group, which was designated Centers for Disease Control (CDC) group nonoxidizer 1 (NO-1). The phenotypic characteristics of CDC group NO-1 were most similar to non-acid-producing Acinetobacter species, with the major difference being a negative reaction in the transformation assay test for Acinetobacter spp. The cellular fatty acid composition of CDC group NO-1 was different from those of Acinetobacter species and all other bacteria tested to date. The isolates were susceptible to a variety of antimicrobial agents including the aminoglycosides, beta-lactam antibiotics, tetracyclines, quinolones, and sulfonamides. Fifty percent of the isolates were resistant to trimethoprim. Ubiquinone-8 was present as the major isoprenoid quinone in CDC group NO-1.

Human Immunodeficiency Virus-Associated Autonomic Neuropathy, Drug Addiction, and Zidovudine Treatment

We would like to make some comments on the work by Rüttimann et al¹on human immunodeficiency virus (HIV)—associated autonomic neuropathy, which we read with interest. In a group of HIV-positive intravenous drug users,²we found that 59.4% of the subjects without neurologic symptoms were showing dysfunction of the autonomic nervous system (ANS) to the same cardiovascular tests mentioned by Rüttimann et al. Also, we have found that more severe ANS involvement is related to the seriousness of the disease (Centers for Disease Control groups). The observation of higher values of circulating immune complex in subjects with more important ANS involvement seems to us a valid support for the hypothesis of an autoimmune pathogenesis of the autonomic neuropathy. In the "Conclusions" section of one of our articles,³we described a subject with acquired immunodeficiency syndrome—dementia complex that manifested a relevant improvement to the ANS functional test response

Prospective multicentric study of the etiology of 1051 bacteremic episodes in 782 cancer patients. CEMIC (French-Belgian Study Club of Infectious Diseases in Cancer).

A total of 1051 bacteremic episodes (782 patients) were prospectively recorded in 10 cancer centers (9 French, 1 Belgian), with: patient's age (mean 53, range 1-89 years), underlying cancer, neutropenia (< 1000 neutrophils/microliters; 233), signs and symptoms, type of i.v. line (percutaneous central: 534; peripheral: 228; central implanted: 304), treatment, blood culture system, number of positive blood culture bottles/total obtained, time to growth. Of all episodes, 23.2% occurred within 48 h of admission. The patients were receiving systemic antibiotics at sampling (on AB) in 34.6% of cases. The 1147 pathogens isolated (86 polymicrobial) were: E. coli (10.7%), Klebsiella-Enterobacter-Serratia (6.1%), other enterobacteriaceae (2.2%), Pseudomonas aeruginosa (4.8%), other nonfermenters (4.7%), coagulase-negative staphylococci (CNS, 40.8%), Staphylococcus aureus (9.9%), streptococci (5.4%), enterococci (2.2%), anaerobes (3.4%), yeasts (3.5%), and other bacteria (6.9%). The CDC (Centers for Disease Control) criteria (1988) were used to assess significance: group 1: pathogenic species (616 episodes; 59%); group 2: clinical signs and isolation of a "contaminant" species (47; 4.5%); group 3: as in group 2 with an i.v. line and empiric antibiotic treatment (181 episodes including 176 CNS; 17%); group 4: non-significant (207 episodes including 203 CNS; 20%). Groups 1-3, in which the episodes were considered to be significant (844 episodes; 80%) were compared with non-significant episodes (Fisher). Significant differences (P < or = 0.05) were seen in time to growth (median growth within 24 h vs 48 h), fever (86% vs 54%), chills (40% vs 3%), hypotension (10% vs 2%), septic shock (9% vs 1%), polymicrobial etiology (10% vs 0.5%), and initiation of empiric antibiotic treatment (71% vs 4%). Bacteremic episodes of CDC groups 1, 3 and 4 were further studied in episodes with a single isolate as a doubtful clinical significance (482 episodes) and episodes with > or = 2 bottles positive of probable clinical significance (569 episodes; 54%). In group 1 (218 doubtful, 398 probably significant episodes) significant differences were seen in chills (36% vs 52%), shock (7% vs 13%), polymicrobial (8% vs 17%), initiation of empiric antibiotic treatment (60% vs 72%); in group 3 (87 doubtful, 94 probably significant) in time to growth delay; in group 4 (177 doubtful, 30 probably significant) in proportion with implanted catheter (26% vs 52%), fever (62% vs 10%), and time to growth. This study confirms the predominant role of Gram-positive cocci in bacteremia occurring in cancer patients.

Cardiac surgery in patients with human immunodeficiency virus infection: indications and results.

Ten patients with human immunodeficiency virus (HIV) infections underwent cardiac surgery using cardiopulmonary bypass. All were in Centers for Disease Control (CDC) group II. The cardiac involvement was either urgent or severely symptomatic in all cases. One patient died due to acquired immunodeficiency syndrome (AIDS) unrelated cause. No complications were encountered in this series. Eight of the nine survivors were available for follow-up. Three of these eight patients progressed to AIDS (CDC group IV) and subsequently died. Five patients are alive and in CDC group II. Prognosis of the HIV infection and the natural history of the cardiac disease are the two main elements to be considered whenever cardiac surgery is required.

High-performance liquid chromatography of corynomycolic acids as a tool in identification of Corynebacterium species and related organisms.

A high-performance liquid chromatography (HPLC) study of 307 strains of Corynebacterium species and related taxa revealed that strains classified as "Corynebacterium aquaticum"; "Corynebacterium asperum"; and Centers for Disease Control (CDC) groups 1, 2, A-3, A-4, A-5, B-1, B-3, E, F-2, and I-2 as well as some unidentified coryneforms do not contain any corynomycolic acids; therefore, they should not be included in the genus Corynebacterium. Such an HPLC method of identification permitted the correct assignment to the genus Rhodococcus of two unpigmented strains of coryneform bacteria whose mycolic acid profiles were comparable to those of Rhodococcus equi. Bacteria belonging to CDC groups ANF-1, ANF-3, F-1, G-1, G-2, and I-1, as well as some other Corynebacterium sp. strains, yielded corynomycolic acid HPLC patterns related to those of Corynebacterium species. Either similarities or differences were observed in the corynomycolic acid profiles of Corynebacterium species tested after culture on sheep blood agar and/or sheep blood agar supplemented with Tween 80, which demonstrated that identification at the species or group level is possible. However, Corynebacterium striatum and CDC group I-1 bacteria as well as CDC group G-1 and group G-2 bacteria had indistinguishable HPLC patterns. Conversely, some variations were observed within some species as Corynebacterium xerosis, C. striatum, and Corynebacterium minutissimum. The evaluation procedure of this HPLC method by mass spectrometry analysis of isolated eluted peaks revealed that analytical reverse-phase HPLC alone does not provide any structural information, since isomers with identical polarities coeluted as a single peak. Nevertheless, HPLC is a rapid and reliable method for identification of corynomycolic acid-containing bacteria in the clinical microbiological laboratory.

Brain-Stem Auditory Evoked Potentials in Human Immunodeficiency Virus-Seropositive Patients With and Without Acquired Immunodeficiency Syndrome

Brain-stem auditory evoked potentials were recorded in 35 human immunodeficiency virus (HIV)-seropositive subjects from the Centers for Disease Control groups III and IV, 24 HIV-negative drug abusers, and 62 normal healthy controls. None of the patients had evidence of neurological complications. History of alcohol consumption was an exclusion criterion. The values of central conduction times I-V and III-V showed significant differences between the HIV-seropositive subjects and normal healthy controls, as well as between the HIV-seropositive subjects and HIV-negative drug abusers. Central conduction times I-III showed no differences between groups, except in the left ear of Centers for Disease Control group IV compared with controls. No statistical differences were found in the central conduction times between HIV-negative drug abusers and normal healthy controls. The results suggest a subclinical involvement of the upper brain stem in HIV infection. It could be produced by direct action of the virus on central nervous system structures.

Centers for Disease Control Group M-6: A Cause of Destructive Endocarditis

Centers for Disease Control Group M-6: A Cause of Destructive Endocarditis

Resting energy expenditure and substrate oxidation in human immunodeficiency virus (HIV)-infected asymptomatic men: HIV affects host metabolism in the early asymptomatic stage

To study the effect of persistent human immunodeficiency virus (HIV) infection on host metabolism, we performed indirect calorimetry in 11 asymptomatic HIV-infected patients (Centers for Disease Control group II or III) who were seropositive for greater than or equal to 1 y, but who still had normal numbers of circulating CD4+ T cells, and in 11 healthy control subjects of similar age and relative body composition. HIV-infected patients had 8% (P less than 0.05) higher rates of resting energy expenditure than did control subjects. Fat-oxidation rates were significantly higher in the patients (means +/- SE: 2.90 +/- 0.08 vs 2.19 +/- 0.17 g.kg FFM-1.d-1, patients vs control subjects, P less than 0.01) whereas no significant differences in carbohydrate-oxidation rates between patients and control subjects were found. These alterations in metabolism were not associated with increased concentrations of catecholamines, cortisol, or thyroid hormones. Mean concentrations of interleukin 6 in the patients were increased only twofold when compared with healthy control subjects. The results indicate that HIV infection affects host metabolism in the early asymptomatic stage, before CD4+ T cell numbers start to decline.