HIV-1 infected patients older than 50 years. PISCIS cohort study.

OBJECTIVE: The aim of this study is to characterize the ways in which older HIV-infected people differ from younger HIV-infected people. METHODS: Prospective cohort study. PISCIS cohort includes newly attended HIV-infected subjects since January 1, 1998. Naive patients were selected. Two groups were defined: G1 (>or=50 years at time of diagnosis, n=493) and G2 (18-49 years, n=4511). Statistical analysis was performed using chi(2), Student's t test, Cox regression and linear mixed models. RESULTS: G1 had different features: males (G1: 84% vs. G2: 75%, p<0.001), sexual transmission (52% vs. 32%, p<0.001), AIDS at first visit (38% vs. 22%, p<0.001). The follow-up was 6 years. Ninety-five percent of patients in G1 and 92% in G2 presented a detectable viral load (>or=500 copies/mm(3)) at the first visit (p=0.016). G1 presented lower CD4 levels with respect to G2 throughout the period but the increase of CD4 in G1 at the end of the study period was 254 cells/mm(3) whereas for G2 it was 196 cells/mm(3) (p<0.001). Mortality was 9% for G1 and 4% for G2 (p<0.001). CONCLUSIONS: HIV-infected people diagnosed at the age of 50 years or older showed different features. They showed good viral and immunological response to HAART.

Serological evidence of Bartonella henselae infection in healthy people in Catalonia, Spain.

Cat scratch disease (CSD), bacillary angiomatosis, hepatic peliosis and some cases of bacteraemia, endocarditis, and osteomyelitis are directly caused by some species of the genus Bartonella. The purpose of this study was to determine the prevalence of IgG antibodies against Bartonella henselae in healthy people and to identify the epidemiological factors involved. Serum samples from 218 patients were examined by indirect immunofluorescence assay (IFA). Significance levels for univariate statistical analysis were determined by the Mann-Whitney U test, chi2 test and Fisher's exact test. Of 218 patients, 99 were female and 119 male, with a median age of 34.36 years (range 0-91 years). Nineteen (8.7%) reacted with B. henselae antigens. Of all the factors concerning the seroprevalence rate being studied (age, sex, contact with animals, residential area), only age was statistically significant. Our serological data seems to indicate that B. henselae is present in Catalonia and could be transmitted to humans.

Seroepidemiological study of Rickettsia felis, Rickettsia typhi, and Rickettsia conorii infection among the population of southern Spain.

Rickettsia typhi and Rickettsia conorii, the etiologic agents of, respectively, murine typhus and Mediterranean spotted fever, are recognized as frequent causes of fever of intermediate duration in southern Spain; in addition, in recent years Rickettsia felis has been detected in potential vectors in this area. Nevertheless, limited data exist regarding the actual prevalence of past infection due to these three pathogens. In the present study, the prevalence of past infection due to R. felis, R. typhi, and R. conorii was determined in a representative population of southern Spain during 2002. In addition, the possible risk factors associated with exposure to these pathogens were investigated. An epidemiological survey was completed by all subjects included in the study. Serum samples were tested by indirect immunofluorescence assay. The prevalence of past infection due to R. felis, R. typhi, and R. conorii among the 504 total subjects was 6.5, 3.8 and 8.7%, respectively. In multivariate analysis, infection due to R. felis was independently associated with a high-risk occupation (one that required working outdoors in nature, close contact with domestic animals, or potential contact with rodents) (OR=5.8; 95%CI 2.1-15.6), while infection due to R. typhi was associated with older age (factor of 1.04 [95%CI 1.008-1.068]) and frequent insect bites (OR=10.3; 95%CI 2.3-45.5). Two factors were associated with infection due to R. conorii: a high-risk occupation (OR=9.3; 95%CI 3.7-23.2), and participation in outdoor activities (OR=7.2; 95%CI 1.4-38.5). The results confirm the widespread prevalence of past infection due to R. felis, R. typhi, and R. conorii in the population of southern Spain.

Presence of human past infections due to the Bar29 rickettsial strain in Southern Spain.

The prevalence of past infections due to Bar29 rickettsial strain in a population from Southern Europe, as well as the possible risk factors associated to exposure to this rickettsia, were analysed. Among the 504 subjects included, global prevalence of past infections was 3.4%. Past infections were significantly more frequent in rural areas compared to urban (10.8 vs. 3.2%, OR 3.6 [1.1-12.3], P = .05), and suburban areas (10.8 vs. 1.9%, OR 6.2 [1.3-28.9], P = .02). In multivariate analysis the factors that were independently associated to past infection due to Bar29 strain were higher age (P = .037; factor of 1.033 [1.002-1.066]), and a risk profession (P = .005; OR = 5.7 [1.6-19.6]). These data point towards the presence of past Bar29 strain infections in a population from Southern Spain.

Cloning and sequencing of the Klebsiella pneumoniae O5 wb gene cluster and its role in pathogenesis.

One representative recombinant clone encoding Klebsiella pneumoniae O5-antigen lipopolysaccharide (LPS) was found upon screening for serum resistance in a cosmid-based genomic library of K. pneumoniae KT769 (O5:K57) introduced into Escherichia coli DH5alpha. A total of eight open reading frames (wb(O5) gene cluster) were necessary to produce K. pneumoniae O5-antigen LPS in E. coli K-12. The enzymatic activities proposed for the wb(O5) gene cluster are in agreement with the activities proposed for the biosynthesis of K. pneumoniae O5-antigen LPS. Using the complete DNA sequence of the K. pneumoniae wb(O5) gene cluster, we obtained (by single or double recombination) genetically well-characterized mutants devoid only of this O5-antigen LPS. Finally, using these O5(-) mutants and the corresponding wild-type strains or complemented mutants with the wb(O5) gene cluster (O5(+) strains), we found that the presence of K. pneumoniae O5-antigen LPS is essential for some pathogenic features like serum resistance, adhesion to uroepithelial cells, and colonization (experimental infections) of the urinary tract in rats.

Cloning, sequencing, and role in serum susceptibility of porin II from mesophilic Aeromonas hydrophila.

We cloned and sequenced the structural gene for Aeromonas hydrophila porin II from strain AH-3 (serogroup O:34). The genetic position of this gene, like that of ompF in Escherichia coli, is adjacent to aspC and transcribed in the same direction. However, upstream of the porin II gene no similarities with E. coli were found. We obtained defined insertion mutants in porin II gene either in A. hydrophila (O:34) or A. veronii sobria (serogroup O:11) serum-resistant or -sensitive strains. Furthermore, we complemented these mutants with a plasmid harboring only the porin II gene, which allowed us to define the role of porin II as an important surface molecule involved in serum susceptibility and C1q binding in these strains.

Two genes from the capsule of Aeromonas hydrophila (serogroup O:34) confer serum resistance to Escherichia coli K12 strains.

The Escherichia coli DH5alpha strain as well as other K12-derived strains are unable to produce O-specific lipopolysaccharide and are thus rough and serum-sensitive. One representative recombinant clone (COS-SR1) containing Aeromonas hydrophila (serogroup O:34) chromosomal DNA conferred serum resistance to E. coli K12 strains. Genetic, biochemical, and immunological studies suggested that the two genes (orf1 and wcaJ) identified in a subclone (pAC-SR9) of COS-SR1 are necessary for the production of the colanic acid capsule at 37 degrees C on E. coli DH5alpha, rendering the strain serum-resistant. A. hydrophila strains from serogroup O:34 are able to produce capsule when they grow both in synthetic medium and in an autolysate of fish viscera. However, defined wcaJ insertion mutants of A. hydrophila 1051-88 (serogroup O:34) are unable to produce capsule on these media. This strongly suggests that both genes belong to the gene cluster responsible for capsule production (wca) of A. hydrophila 1051-88 (serogroup O:34).

Cloning, sequencing, and role in virulence of two phospholipases (A1 and C) from mesophilic Aeromonas sp. serogroup O:34.

Two different representative recombinant clones encoding Aeromonas hydrophila lipases were found upon screening on tributyrin (phospholipase A1) and egg yolk agar (lecithinase-phospholipase C) plates of a cosmid-based genomic library of Aeromonas hydrophila AH-3 (serogroup O34) introduced into Escherichia coli DH5alpha. Subcloning, nucleotide sequencing, and in vitro-coupled transcription-translation experiments showed that the phospholipase A1 (pla) and C (plc) genes code for an 83-kDa putative lipoprotein and a 65-kDa protein, respectively. Defined insertion mutants of A. hydrophila AH-3 defective in either pla or plc genes were defective in phospholipase A1 and C activities, respectively. Lecithinase (phospholipase C) was shown to be cytotoxic but nonhemolytic or poorly hemolytic. A. hydrophila AH-3 plc mutants showed a more than 10-fold increase in their 50% lethal dose on fish and mice, and complementation of the plc single gene on these mutants abolished this effect, suggesting that Plc protein is a virulence factor in the mesophilic Aeromonas sp. serogroup O:34 infection process.

Activation of the complement classical pathway (C1q binding) by mesophilic Aeromonas hydrophila outer membrane protein.

The mechanism of killing of Aeromonas hydrophila serum-sensitive strains in nonimmune serum by the complement classical pathway has been studied. The bacterial cell surface component that binds C1q more efficiently was identified as a major outer membrane protein of 39 kDa, presumably the porin II described by D. Jeanteur, N. Gletsu, F. Pattus, and J. T. Buckley (Mol. Microbiol. 6:3355-3363, 1992), of these microorganisms. We have demonstrated that the purified form of porin II binds C1q and activates the classical pathway in an antibody-independent manner, with the subsequent consumption of C4 and reduction of the serum total hemolytic activity. Activation of the classical pathway has been observed in human nonimmune serum and agammaglobulinemic serum (both depleted of factor D). Binding of C1q to other components of the bacterial outer membrane, in particular to rough lipopolysaccharide, could not be demonstrated. Activation of the classical pathway by this lipopolysaccharide was also much less efficient than activation by the outer membrane protein. The strains possessing O-antigen lipopolysaccharide bind less C1q than the serum-sensitive strains, because the outer membrane protein is less accessible, and are resistant to complement-mediated killing. Finally, a similar or identical outer membrane protein (presumably porin II) that binds C1q was shown to be present in strains from the most common mesophilic Aeromonas O serogroups.