Performance of molecular and serologic tests for the diagnosis of scrub typhus.

Diagnosis of scrub typhus, caused by the bacterium Orientia tsutsugamushi, is challenging because of the overlap of its non-specific symptoms with other infections coupled with the lack of sufficient data on the performance of diagnostic tests. Early diagnosis of scrub typhus is crucial to improve outcomes and this study evaluates the diagnostic performance of various tests. The present study aims at assessing the accuracy of various rapid diagnostic tests, serologic tests, and nucleic acid amplification methods on well-characterized patient samples. Adult patients with acute febrile illness and manifestations suggestive of scrub typhus confirmed by positive PCR in the blood, eschar or tissue were characterized as cases. Patients with acute febrile illness and a confirmed alternate etiology such as culture-confirmed typhoid, smear/PCR positive for malaria, PCR/NS1 antigen positive for dengue, PCR positive for influenza, PCR/MAT positive for leptospirosis, PCR positive for spotted fever were characterized as controls with other infections. The healthy controls consisted of subjects from the same geographic region. We performed the following tests on blood samples for scrub typhus and calculated the sensitivity, specificity, positive predictive value, and negative predictive value: (1) Quantitative real time PCR using 47kDa gene (qPCR); (2) Conventional PCR using 56kDa gene (cPCR); (3) Loop-mediated isothermal amplification assay (LAMP assay); (4) Immunofluorescence assay (IFA); (5) Enzyme-linked immunosorbent assay (ELISA); (6) Weil-Felix test(WF test); and (7) Immunochromatographic Rapid Diagnostic Test (RDT).Among the 316 participants, 158 had confirmed scrub typhus (cases) and 158 were controls. ELISA and RDT detecting Orientia tsutsugamushi specific IgM antibodies had excellent discriminative potential with sensitivities and specificities of 92%, 94% and 92%, 92% respectively. The sensitivity and specificity of IFA were found to be 95% and 74% respectively. IgM serology had a false positivity rate of 8% with other acute febrile illnesses such as dengue, leptospirosis and spotted fever due to the nonspecific binding of the pentavalent IgM. LAMP assay had 91.7% sensitivity and 77.2% specificity while qPCR provided excellent sensitivity (97%) and perfect specificity. In conclusion, ELISA and RDT detecting Orientia tsutsugamushi specific IgM antibodies have excellent sensitivity and specificity while the accuracy of IFA is suboptimal for the diagnosis of scrub typhus. Given its perfect specificity and superior sensitivity, qPCR is preferred for diagnostic confirmation in reference laboratories particularly for diagnosis of early disease with less than 7 days duration. This study provides a comprehensive evaluation of all currently available diagnostic tests for scrub typhus.

Evaluation of an in-house LipL32 polymerase chain reaction for diagnosis of leptospirosis and its correlation with various serological diagnostic techniques.

BACKGROUND: Leptospirosis is a zoonotic disease of ubiquitous distribution. During rainy seasons, in spring and summer and also during harvest times, the risk of leptospirosis increases as there are chances of frequent contact with infected rat population which is common in Karnataka as farming is a main source of income to the people here. There is a paucity of data regarding the prevalent serovars from Karnataka. This study was undertaken as an attempt to compare a battery of tools such as immunochromatographic test (ICT), microscopic agglutination test (MAT), immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and in-house polymerase chain reaction (PCR) to detect leptospirosis. SETTINGS AND DESIGN: This study using consecutive sampling technique was conducted in a tertiary care centre, Mysore, Karnataka. SUBJECTS AND METHODS: Samples from 783 suspected cases of leptospirosis in and around Mysore between April 2013 and April 2016 were processed. Samples from 783 patients suspected of leptospirosis were subjected to ICT, IgM ELISA, MAT and in-house PCR. STATISTICAL ANALYSIS USED: The statistical analysis was carried out using SPSS software version. RESULTS: Among 783 samples tested, only 14 (1.7%) were positive by ICT, 341 (44%) were positive by IgM ELISA, 368 (47%) were positive by MAT and 393 (50.2%) were positive by in-house PCR. CONCLUSIONS: Mysore can be considered endemic for leptospirosis. The in-house PCR based on LipL32 gene proved to be useful in the early diagnosis of leptospirosis.

Is Language a Factor in the Perception of Foreign Accent Syndrome?

Neurogenic foreign accent syndrome (FAS) is diagnosed when listeners perceive speech associated with motor speech impairments as foreign rather than disordered. Speakers with foreign accent syndrome typically have aphasia. It remains unclear how far language changes might contribute to the perception of foreign accent syndrome independent of accent. Judges with and without training in language analysis rated orthographic transcriptions of speech from people with foreign accent syndrome, speech-language disorder and no foreign accent syndrome, foreign accent without neurological impairment and healthy controls on scales of foreignness, normalness and disorderedness. Control speakers were judged as significantly more normal, less disordered and less foreign than other groups. Foreign accent syndrome speakers' transcriptions consistently profiled most closely to those of foreign speakers and significantly different to speakers with speech-language disorder. On normalness and foreignness ratings there were no significant differences between foreign and foreign accent syndrome speakers. For disorderedness, foreign accent syndrome participants fell midway between foreign speakers and those with speech-language impairment only. Slower rate, more hesitations, pauses within and between utterances influenced judgments, delineating control scripts from others. Word-level syntactic and morphological deviations and reduced syntactic and semantic repertoire linked strongly with foreignness perceptions. Greater disordered ratings related to word fragments, poorly intelligible grammatical structures and inappropriate word selection. Language changes influence foreignness perception. Clinical and theoretical issues are addressed.

Acenocoumarol and phenytoin toxicity in the presence of CYP2C9 mutation.

This case report describes a rare interaction between therapeutic doses of phenytoin and acenocoumarol resulting in both acute phenytoin toxicity and increased international normalized ratio (INR). Interactions between these drugs are due to the pharmacokinetics and the common metabolising pathway by hepatic cytochrome P450 isoenzyme-CYP2C9. Our patient was detected to be homozygous for CYP2C9*3 by PCR-RFLP analysis resulting in markedly decreased metabolism of both the drugs. Given that these two drugs are often given concomitantly in the medical out patient department, and that CYP2C9 polymorphisms are not uncommon, clinicians should be aware of this interaction and suspect this in patients with toxicity to these drugs.