Genotyping of Chlamydia trachomatis is limited by the low sequence variation in the genome, and no adequate method is available for analysis of the spread of chlamydial infections in the community. We have developed a multilocus sequence typing (MLST) system based on five target regions and compared it with analysis of ompA, the single gene most extensively used for genotyping. Sequence determination of 16 reference strains, comprising all major serotypes, serotypes A to L3, showed that the number of genetic variants in the five separate target regions ranged from 8 to 16. The genetic variation in 47 clinical C. trachomatis isolates of representative serotypes (14 serotype D, 12 serotype E, 11 serotype G, and 10 serotype K strains) was analyzed; and the MLST system detected 32 variants, whereas 12 variants were detected by using ompA analysis. Specimens of the predominant serotype, serotype E, were differentiated into seven genotypes by MLST but into only two by ompA analysis. The MLST system was applied to C. trachomatis specimens from a population of men who have sex with men and was able to differentiate 10 specimens of one predominant ompA genotype G variant into four distinct MLST variants. To conclude, our MLST system can be used to discriminate C. trachomatis strains and can be applied to high-resolution molecular epidemiology.Chlamydia trachomatis can be subdivided by serological typing, based on the major outer membrane protein, into at least 15 serotypes. Serotypes A to C are associated with ocular trachoma, serotypes D to K preferably colonize the urogenital tract, and serotypes L1 to L3 cause lymphogranuloma venereum.Serotyping of Chlamydia is laborious since it requires multiple passages in cell culture and the use of a large panel of monoclonal antibodies. Genotyping methods are more commonly used, and the major outer membrane protein gene, ompA, provides the best discriminatory capacity of the genes tested. Restriction fragment length polymorphism analysis of ompA is rapid, and its results show a high level of agreement with the results serotyping (9), while DNA sequencing of ompA has a higher resolution and can discriminate strains in clinically high-risk populations (2, 14). However, when it is applied to nonselected populations, the limited resolution of ompA sequencing restricts the amount of epidemiological information that can be obtained (6). This is especially true, given that the single serotype E comprises almost half of all urogenital chlamydial infections, and within this serotype, one genotypic variant appears to predominate (3, 4, 6). There is therefore an obvious need to develop better methods for evaluation of the molecular epidemiology of chlamydial infections. Furthermore, it has recently been shown that mutant strains evade systems commonly used for the detection of C. trachomatis (11). At present little is known about the spread of such changed chlamydial strains, but they are known to be prevalent in several regions of Sweden and are probably prevalent elsewhere. In this conte...

Background: Adequate peri-operative analgesia may reduce post-operative stress response and improve recovery in laboratory animals. We have established a method involving repeated automated blood sampling, allowing quantification of serum corticosterone levels in rats for stress assessment without stress-inducing handling or restraint. In the present study, the effects of the commonly used route of buprenorphine administration (0.05 mg/kg injected subcutaneously) were compared with oral administration (0.4 mg/kg mixed with Nutella® and orally administered by voluntary ingestion) in male Sprague-Dawley rats. Methods: A catheter was placed in the jugular vein and attached to an Accusampler® for automated blood sampling. During 96 h after surgery, blood was collected at specified time points. Pre- and post-operative body weights and water consumption were registered. Results: Buprenorphine significantly suppressed levels of circulating corticosterone after the oral but not after the subcutaneous treatment. Both buprenorphine treatments had a positive impact on maintenance of body weight and water consumption, compared to the control group that received no buprenorphine. Conclusion: The present investigation suggests that oral voluntary ingestion ad libitum is an efficacious, convenient and non-invasive way of administering peri-operative buprenorphine to rats, as judged by corticosteroid response and effects on body weight and water consumption.

The present study investigated the postoperative plasma concentrations of corticosterone and buprenorphine in male Wistar and Sprague-Dawley rats, treated with buprenorphine administered either through subcutaneous (SC) injection or through voluntary ingestion (VI). The animals were treated with buprenorphine for pre-emptive analgesia prior to surgical placement of a jugular catheter, followed by automated blood sampling during 96 h. Buprenorphine was administered on a regular basis throughout the experiment, and blood was collected on selected time points. Body weight was measured before and 96 h after surgery. It was found that the two rat stocks responded in a similar manner to both buprenorphine treatments, with the exception of body weight change in Wistar rats, in which body weight was reduced after SC treatment. The plasma concentration of corticosterone was significantly higher in the SC-treated animals than in the VI-treated animals during the first 18 h of the study, while plasma buprenorphine concentration was at least as high and more even over time after VI treatment. The present study shows that buprenorphine administration through VI is suitable for both Wistar and Sprague-Dawley rats, with lower stress response and higher plasma concentrations of buprenorphine than after the traditional SC route of administration.

Tissue injury and anaesthesia during surgery induce a stress response associated with increased glucocorticoid secretion from the adrenal glands. This response alters the normal physiology and may cause postoperative morbidity, as well as affect the results during acute experiments. The aim of the present investigation was to study the effect of surgical severity and analgesic treatment on circulating corticosterone in male Sprague-Dawley rats. Male rats were treated with either lidocaine infiltrated during surgery, buprenorphine (0.05 or 0.1 mg/kg subcutaneously) or saline subcutaneously. Each treatment group was subjected to either arterial catheterisation or arterial catheterisation and laparotomy. A catheter was inserted in the common carotid artery and blood was collected during surgery and during anaesthesia 6 h after surgery. Lidocaine treatment reduced the corticosterone levels compared to saline treatment after catheterisation but not after laparotomy. Buprenorphine treatment reduced the corticosterone levels during the first hour after surgery after both catheterisation and laparotomy. The higher buprenorphine dose led to an earlier and more pronounced reduction, especially after laparotomy. In the present study, the corticosterone response during surgery in laboratory rats is correlated with the severity of the procedure, and buprenorphine reduces the surgical stress response more effectively than lidocaine treatment.

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