Diagnosis

Diagnostic techniques have been developed primarily for the detection of T. vaginalis but are equally applicable to the detection of T. tenax. Diagnosis of Trichomonas traditionally depends on the microscopic observation of motile protozoa. Although this technique is rapid, specific, and cost effective, it has a low sensitivity detecting only half of the culture positive samples.[23] The low sensitivity is probably due to the loss of the distinctive motility after the parasite has been removed from body temperatures for any length of time. Sensitivity is increased if specimens are examined immediately after being taken.

The culture method is the gold standard for the detection of Trichomonas; however, culture requires an inoculum of 300 to 500 trichomonads/mL[24] and up to 7 days before a sample could be reported as negative. During this period positive patients may continue transmitting the disease. Moreover, inadequate transport or storage of samples may result in a negative culture. The InPouch TV system (BioMed Diagnostics, San Jose, CA) is considered the most advantageous culture systems. It consists of a two-chambered bag that allows performing an immediate wet-mount microscopic examination through the bag as well as a culture,[25] but as with other culture techniques sensitivity may vary especially according to rapid access to incubators.

Cell culture is more sensitive than broth culture and wet-mount preparation; however, cell culture is not routinely performed and is neither convenient nor used at present for rapid diagnosis.[24]

Papanicolaou (Pap) smear and other staining techniques have also been performed as a detection tool for trichomonas.1-26,27-1 Papanicolaou smear is preferred as it is routinely performed in gynecological screening for cytological abnormalities. Staining techniques are not reliable, however, as Trichomonas does not always appear in its typical pear-shape form.

Detection of T. vaginalis based on antibody detection is not reliable because of serotype differences among different strains and because host response to the parasite is widely variable. In addition, infection of T. vaginalis by a double-stranded RNA virus (the T. vaginalis virus, TVV) may influence expression of antigenic proteins.[28]

Detection of the parasite in clinical samples using labeled monoclonal antibodies has shown similar sensitivity and specificity results to those obtained by culture.[29]

Techniques based on DNA analysis have been increasingly used in clinical laboratories to improve the specificity and sensitivity of T. vaginalis diagnosis. Hybridization techniques such as the Affirm VP system

(MicroProbe Corp., Bothwell, WA) or the dot blot and in situ hybridization demonstrated a better performance than the wet-mount preparation. However, the number of false-negative results was high when the Affirm VP system was tested.[30] The requirement for radioactive material for the dot blot and in situ hybridization is the main drawback of these techniques.

Polymerase chain reaction-based techniques have been widely explored for the detection of both T. vaginalis and T. tenax. Repetitive DNA sequences of T. vaginalis have been cloned, sequenced, and characterized for PCR amplification;[31,32] however, low sensitivity is observed because of the high variability of these sequences and the presence of insertion elements, causing more than a single product or absence of amplification. The beta tubulin gene has also been used as a target for PCR amplification, but this PCR shows a cross-reaction with some T. tenax isolates and fails to amplify some axenically cultivated T. vaginalis isolates.[33] Techniques based on the amplification of ribosomal coding DNA sequences have been described both for T. tenax[34] and T. vaginalis.[35] Ribosomal genes (rDNA) have been demonstrated to be highly conserved among different Trichomonas strains;[2] also, ribosomal genes are generally multicopy genes. The nature of the rDNA genes made them the most advantageous target for PCR-based detection. Both human Trichomonas are capable of invading organs and tissue that are not their natural environment making them difficult to identify using current techniques; rDNA-based PCR is especially useful when those cases occur.

Random amplified polymorphic DNA (RAPD) amplification may be useful to characterize T. vaginalis strains according to resistance to metronidazole, and infection with TVV or mycoplasmas; however, virulence of strains or geographic distribution has not been genotypically correlated.1-36-1

Antigenic differences between T. tenax isolates from respiratory passages and isolates from the oral cavity have suggested that the isolates from the respiratory passages may belong to a separate species.[3] However, no further studies have been conducted in this regard. The use of molecular biology techniques should be able to provide a definitive answer to whether there is a difference in the oral and respiratory T. tenax isolates.

whether symptomatic or asymptomatic, should be treated to prevent reinfection. Both regimens are equally effective.[37]

Although treatment is highly effective, resistance of T. vaginalis to metronidazole is now on the rise, and according to the Centers for Disease Control 5% of all T. vaginalis patient isolates have some level of resistance to metronidazole.1-38-1

The mechanism of metronidazole resistance may be a consequence of a reduced transcription of the ferredoxin gene and/or a consequence of abolished or decreased activities of the pyruvate-ferredoxin oxidoreductase and hydrogenase enzymes.[39]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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