ABSTRACT
National health statistics report a 2·5-fold increase in laboratory-confirmed Chlamydia trachomatis (CT) cases over the last decade in Switzerland where no CT screening programme exists. We obtained essential denominator information to describe the epidemiology of CT in the canton of Basel-Stadt, an urban canton in north-western Switzerland. Laboratories reporting at least two CT infections from Basel-Stadt residents to the SFOPH in 2010 provided demographic and test-related data. CT positivity rates were calculated for 20022010. The influences of test year, age, sex and laboratory on CT positivity were investigated in a multivariable model. Positivity differed between sexes and age groups. In our sample of 32 034 records, female and male CT positivity rates were 4·7% and 11·1%, respectively. Test year was significantly associated with test outcome in the multivariable analysis but no time trend was observed. CT positivity did not change over the past 9 years in Basel-Stadt. In contrast to other European countries without CT screening, we found no evidence that the observed increase of Chlamydia cases in the national notification system represents an epidemiological trend, but rather results from an increased testing frequency.
Subject(s)
Chlamydia Infections/epidemiology , Chlamydia Infections/microbiology , Chlamydia trachomatis/isolation & purification , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , Prevalence , Risk Factors , Switzerland/epidemiology , Young AdultABSTRACT
The application of molecular techniques to investigate strain relatedness may help define the local epidemiology of Mycobacterium avium infection, and, by identifying false isolates (i.e. neither pathogens nor colonizers) resulting from contamination, may serve as a tool for quality control in the laboratory. For this purpose, isolates from all patients (n = 129) with Mycobacterium avium infections identified over a two-year period were investigated by pulsed-field gel electrophoresis (PFGE). Of 38 PFGE patterns identified, 34 corresponded to unique strains or to isolates present in no more than two or three individuals. One prevalent strain was identified among HIV-infected patients and three patterns were related to culture contamination events. PFGE (i) established the diversity of Mycobacterium avium strains in a community; (ii) identified the existence of a unique strain that may account for one-fifth of Mycobacterium avium isolated from HIV-infected patients locally; (iii) documented the extent and resolution of a suspected pseudo-outbreak; and (iv) uncovered an additional-unsuspected contamination event.
Subject(s)
AIDS-Related Opportunistic Infections/epidemiology , Mycobacterium Infections/epidemiology , Mycobacterium avium/isolation & purification , AIDS-Related Opportunistic Infections/microbiology , Electrophoresis, Gel, Pulsed-Field , Humans , Molecular Epidemiology , Mycobacterium Infections/microbiology , Mycobacterium avium/classification , Sensitivity and SpecificityABSTRACT
The insertion sequence IS1245 is a novel mycobacterial repetitive element identified in Mycobacterium avium. It encodes a transposase which exhibits a 64% amino acid similarity with IS1081, an insertion element present in the M. tuberculosis complex. The host range of IS1245 appears limited to M. avium as this element was not identified in M. intracellulare or in any other of 18 mycobacteria species tested. When IS1245 was used for restriction fragment length polymorphism (RFLP) analysis, human isolates characteristically presented a high number of copies (median, 16; range, 3 to 27) and a diversity of RFLP patterns comparable to that found by pulsed-field gel electrophoresis. Isolates from nonhuman sources differed both in number of copies and in RFLP pattern diversity: while swine isolates shared the characteristics of human strains, those from several avian sources exhibited a very low copy number of IS1245 and appeared clonal on the basis of RFLP.
Subject(s)
DNA Transposable Elements , Mycobacterium avium Complex/genetics , Mycobacterium avium/genetics , Animals , Base Sequence , DNA Primers/genetics , DNA, Bacterial/genetics , Gene Amplification , Humans , Molecular Sequence Data , Mycobacterium/genetics , Mycobacterium avium/classification , Mycobacterium avium/isolation & purification , Mycobacterium avium Complex/classification , Mycobacterium avium Complex/isolation & purification , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Repetitive Sequences, Nucleic Acid , Species SpecificityABSTRACT
Mycobacterium avium was recovered from 21 birds and 10 pigs. Bird isolates carried IS901 and a few copies of IS1245 and appeared highly related by pulsed-field gel electrophoresis. Pig isolates showed features previously described in human isolates: a lack of IS901, a high copy number of IS1245, and marked polymorphism by pulsed-field gel electrophoresis.
