RESUMEN
Clostridium difficile is a well recognized pathogen of humans and animals. Although C. difficile was first identified over 70 years ago, much remains unknown in regards to the primary source of human acquisition and its pathobiology. These deficits in our knowledge have been intensified by dramatic increases in both the frequency and severity of disease in humans over the last decade. The changes in C. difficile epidemiology might be due to the emergence of a hypervirulent stain of C. difficile, ageing of the population, altered risk of developing infection with newer medications, and/or increased exposure to C. difficile outside of hospitals. In recent years, there have been numerous reports documenting C. difficile contamination of various foods, and reports of similarities between strains that infect animals and strains that infect humans as well. The purposes of this review are to highlight the many challenges to diagnosing, treating, and preventing C. difficile infection in humans, and to stress that collaboration between human and veterinary researchers is needed to control this pathogen.
Asunto(s)
Clostridioides difficile/patogenicidad , Enterocolitis Seudomembranosa/transmisión , Enterocolitis Seudomembranosa/veterinaria , Zoonosis , Animales , Enfermedades Transmisibles Emergentes/epidemiología , Enfermedades Transmisibles Emergentes/prevención & control , Enfermedades Transmisibles Emergentes/transmisión , Enfermedades Transmisibles Emergentes/veterinaria , Enterocolitis Seudomembranosa/epidemiología , Enterocolitis Seudomembranosa/prevención & control , Contaminación de Alimentos , Microbiología de Alimentos , Humanos , Incidencia , Control de Infecciones/métodos , Factores de Riesgo , VirulenciaRESUMEN
A six-year prospective study of Chlamydia trachomatis infection and ocular disease in Tanzanian village children was conducted to identify the determinants of trachoma endemicity using sequencing of ompA. Overall, 749 conjunctival samples were obtained, with 176 children sampled in both 1989 and 1995. 31.1% (233/749) were positive by PCR-enzyme immunoassay, and 76% (176/233) of the positives were sequenced in variable domains (VD) 1 to 4 (22 children in both 1989 and 1995). Twenty-six ompA genotypes of serovar A, and 19 of B/Ba were identified, and only 20% of genotypes identified in 1995 matched those found in 1989. In particular, B/Ba genotypes exhibited a 15-base region in VD 2 with increased nucleotide substitution, and these types were associated with age and water availability. Homotypic infection and infection with multiple genotypes and high chlamydial load did predict subsequent severe trachoma (odds ratio (OR) = 10.14, 95% confidence interval (CI): 1.71, 60.23; OR = 6.40, 95% CI: 0.75, 54.41; OR = 6.74, 95% CI: 0.82, 55.38, respectively). And, multitypic infection was clustered with residence of village and associated with familial cattle ownership. In conclusion, high ompA polymorphism and the inability of some hosts to clear infection with the same ompA genotype suggest two distinct but converging mechanisms of endemic severe trachoma.
Asunto(s)
Proteínas de la Membrana Bacteriana Externa/genética , Chlamydia trachomatis/genética , Polimorfismo Genético , Tracoma/epidemiología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Bovinos , Niño , Preescolar , Chlamydia trachomatis/inmunología , Chlamydia trachomatis/aislamiento & purificación , Enfermedades Endémicas , Estudios de Seguimiento , Genotipo , Humanos , Datos de Secuencia Molecular , Filogenia , Estudios Prospectivos , Salud Rural , Tanzanía/epidemiología , Tracoma/inmunología , Tracoma/microbiologíaRESUMEN
The authors investigated the long-term stability of risk factors in predicting the presence of active trachoma and severe inflammatory trachoma in 176 children in Kongwa, Tanzania, who were aged 1 and 2 years in 1989 and were available for follow-up in 1995. Familial cattle ownership, living more than 2 hours away from a water source, and facial cleanliness at both time points were associated with the presence of active trachoma at both time points (odds ratio (OR) = 2.58, 95% confidence interval (CI): 1.15, 5.79; OR = 3.07, 95% CI: 1.23, 7.64; and OR = 0.52, 95% CI: 0.26, 1.03, respectively). An association of familial cattle ownership with facial cleanliness and water accessibility was observed. Having a clean face at both time points was associated with lower odds of active trachoma at both time points for children in non-cattle-herding families (OR = 0.40, 95% CI: 0.18, 0.87). Living more than 2 hours away from a water source at both time points increased the odds of active trachoma at both time points in children of cattle-herding families (OR = 8.00, 95% CI: 1.99, 32.10). Noticeably, severe inflammatory trachoma at baseline predicted mortality in children from villages in which trachoma was less common (OR = 3.75, 95% CI: 1.09, 12.98). The results suggest that risk factor reduction could diminish persistent disease.
Asunto(s)
Higiene , Tracoma/epidemiología , Animales , Antibacterianos/uso terapéutico , Bovinos , Niño , Escolaridad , Monitoreo del Ambiente/métodos , Monitoreo Epidemiológico , Femenino , Estudios de Seguimiento , Humanos , Lactante , Modelos Logísticos , Masculino , Prevalencia , Factores de Riesgo , Índice de Severidad de la Enfermedad , Tanzanía/epidemiología , Tetraciclina/uso terapéutico , Tracoma/clasificación , Tracoma/tratamiento farmacológico , Tracoma/etiología , Abastecimiento de AguaRESUMEN
OBJECTIVE: To identify Chlamydia trachomatis by the polymerase chain reaction (PCR) in fallopian tube tissues with chronic salpingitis. DESIGN: Retrospective case-control study. SETTING: Academic tertiary institution. PATIENT(S): Women with a pathological diagnosis of chronic salpingitis or normal fallopian tube hospitalized between September 1992 and November 1994. Initial identification of 248 specimens with final analysis of 154. INTERVENTION(S): Paraffin-embedded fallopian tube tissues were analyzed with use of PCR to detect C. trachomatis. MAIN OUTCOME MEASURE(S): Identification of C. trachomatis DNA; demographics of age, ethnicity, parity, history of sexually transmitted disease, and surgical procedure. RESULT(S): C. trachomatis DNA was detected in 9 of 77 chronic salpingitis cases. Seventy-seven controls were negative for C. trachomatis. No statistically significant difference in age or ethnicity between cases and controls was identified. Nulliparity was more frequent in cases (26 of 74) than controls (14 of 76). Sexually transmitted disease history was more prevalent in cases (24 of 74) than controls (6 of 76). Chlamydia infection was not associated with a particular surgical indication. CONCLUSION(S): Chronic salpingitis is highly associated with the presence of C. trachomatis infection as detected by PCR.
Asunto(s)
Infecciones por Chlamydia/diagnóstico , Chlamydia trachomatis/genética , ADN Bacteriano/análisis , Salpingitis/microbiología , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Infecciones por Chlamydia/complicaciones , Enfermedad Crónica , Femenino , Humanos , Persona de Mediana Edad , Parafina , Reacción en Cadena de la Polimerasa/métodos , Estudios Retrospectivos , Salpingitis/etiologíaRESUMEN
The immediate study objective was to determine if variable disease severity in children with trachoma could be attributable in part to host variation in the ability to clear Chlamydia trachomatis infection. Identification of sibling cohorts with these variant phenotypes would be useful for immunogenetic studies. A weekly survey for 3 months in a trachoma-hyperendemic village using detection of chlamydial DNA and grading of disease severity indicated that 62% (33/53) of children had at least one infection episode. Of those, 64% (21/33) who were persistently infected had both significantly higher mean chlamydial DNA loads and more severe trachoma than did sporadically infected children. Of importance, duration of infection differed between siblings in 60% (6/10) of families. The results suggest that chlamydial load and duration of infection determine the chronic nature of severe disease in trachoma and that host variable efficiency for chlamydial clearance between siblings is in part determined by host variation.
Asunto(s)
Chlamydia trachomatis/crecimiento & desarrollo , Porinas , Tracoma/genética , Tracoma/inmunología , Adenovirus Humanos/genética , Factores de Edad , Proteínas de la Membrana Bacteriana Externa/genética , Secuencia de Bases , Niño , Preescolar , Chlamydia trachomatis/patogenicidad , Enfermedad Crónica , ADN Bacteriano/análisis , ADN Bacteriano/genética , ADN Viral/análisis , ADN Viral/genética , Femenino , Antígenos HLA-DR/genética , Humanos , Lactante , Estudios Longitudinales , Masculino , Datos de Secuencia Molecular , Linaje , Reacción en Cadena de la Polimerasa , Índice de Severidad de la Enfermedad , Factores SexualesRESUMEN
DNA was amplified by polymerase chain reaction from the gene encoding the major outer membrane protein (MOMP) of Chlamydia pneumoniae in order to examine the relatedness of strains isolated from diverse geographical regions. Primers for this reaction were chosen to span a 207-bp region comparable to that of the fourth variable segment of the MOMP gene of Chlamydia trachomatis. Among C. trachomatis, sequence heterogeneity is characteristic within variable sequence domain IV (VDIV) and correlates with serovar type. In contrast, sequence analysis of polymerase chain reaction products from 13 C. pneumoniae isolates indicated that all tested strains were identical in this segment of the MOMP gene. The predicted amino acid sequences from the C. pneumoniae VDIV gene products shared only 13.3 to 30% homology with published VDIV regions from serovars of C. trachomatis. Homology of these VDIV amino acid sequences with sequences from strains of C. psittaci ranged from 45.7 to 60%. The sequence conservation of the VDIV region of the MOMP gene indicates that C. pneumoniae strains may be more genetically homogeneous than C. trachomatis or Chlamydia psittaci strains. Future investigations of antigenic diversity among C. pneumoniae strains should be aimed at the evaluation of variation in other regions of the C. pneumoniae genome.
Asunto(s)
Proteínas de la Membrana Bacteriana Externa/genética , Chlamydophila pneumoniae/genética , Genes Bacterianos , Secuencia de Aminoácidos , Secuencia de Bases , Datos de Secuencia MolecularRESUMEN
The Culturette Brand Clostridium difficile test (CDT; Marion Laboratories, Inc., Kansas City, Mo.) is a latex agglutination test for C. difficile. The recent controversy involving the identity of antigens detected by CDT has made decisions on its use difficult. We compared the test results with those of selective culture and stool cytotoxin assays in investigations of two nursing home outbreaks of C. difficile-associated disease in order to formulate usage recommendations. Selective culture for C. difficile identified 27 (19%) of 142 subjects as carriers. CDT and the stool cytotoxin assay identified only 52 and 48% of these carriers, respectively. Compared with the stool cytotoxin assay, CDT had a high sensitivity (92%) and specificity (89%) for the detection of C. difficile disease, but the positive predictive value of the test was only 17% when the prevalence of disease was 2%. We conclude that the CDT should not be used to identify carriers but that it is a sufficiently sensitive and specific screening test for diagnosing C. difficile disease. However, since the positive predictive value of the CDT is low when the prevalence of disease is low, positive test results should be confirmed by the stool cytotoxin assay.