In-house Multiplex Polymerase Chain Reaction Research Articles

Evaluation of Xpert MTB/RIF Assay on Stool Samples for the Diagnosis of Pulmonary Tuberculosis among the Pediatric Population.

Objective Microbiological confirmation of tuberculosis (TB) in pediatric cases is challenging due to its paucibacillary nature and difficulty in specimen collection. This study aimed to validate stool as an alternative sample for the diagnosis of pediatric pulmonary TB via Xpert MTB/RIF (Xpert) assay. Materials and Methods This cross-sectional study included 75 pediatric patients up to 10 years of age with signs and symptoms suggestive of TB. From each recruited patient, pulmonary and stool samples were collected in a sterile container. The collected samples were subjected to Ziehl-Neelsen staining, BACTEC MGIT 960 culture (MGIT), Xpert, and in-house multiplex polymerase chain reaction for TB diagnosis. Results About 13.33% (10/75) of the pulmonary samples and, of them, 50% (5/75) of the stool samples were positive by Xpert assay. The sensitivity and specificity of Xpert assay with stool and pulmonary samples were 50 (95% confidence interval [CI]: 18.71-81.29%) and 100% (95% CI: 94.48-100%), respectively. Conclusion The Xpert assay on stool samples showed limited sensitivity and good specificity in the diagnosis of pulmonary TB. Therefore, it can be proposed as an alternative screening sample to diagnose TB in pediatric cases for which getting a respiratory sample is extremely difficult. However, further studies with greater number of samples and multiple baseline variables are required to support our findings. Strategies to optimize stool Xpert assay should be performed to enhance the sensitivity of this method to detect Mycobacterium tuberculosis in children.

Standardization of an in-house multiplex real-time polymerase chain reaction for the simultaneous detection of Toxoplasma gondii, Rubella virus, cytomegalovirus, herpes simplex Virus 1 and 2, and Treponema pallidum infection among pregnant women.

An in-house multiplex real-time polymerase chain reaction (PCR) was developed in two cocktails for the identification of six Toxoplasma gondii, Rubella virus, cytomegalovirus, herpes simplex virus (1 and 2), and Treponema pallidum (syphilis) (TORCH-S) agents, which causes congenital infection among pregnant women. Standardization and validation of an in-house multiplex real-time PCR assay for the detection of TORCH-S infection. This study was conducted from February 2017 to February 2019. Primers specific for T. gondii, Rubella virus, cytomegalovirus, herpes simplex virus (1 and 2), and T. pallidum were designed using Primer3 software (https://bioinfo.ut.ee/primer3-0.4.0/). The primer sequences obtained were subjected to BLAST analysis using BLAST database. Synthetic DNA was obtained to use as positive control templates for all the six TORCH-S agents. The lower limit of the detection was performed using plasmid construct for each virus serially diluted from 10-1 to 10-9. An in-house multiplex real-time PCR was standardized and validated in two cocktails for TORCH-S agents, cocktail-1 (HSV1, rubella, and T. gondii), and cocktail-2 (HSV2, CMV, and T. pallidum). The lower limit of the detection for HSV1, rubella, and Toxoplasma were 60.7 copies/10 μl input, 76.4 copies/10 μl input, and 34.4 copies/10 μl input and for HSV2, CMV, and T. pallidum were 80.8 copies/10 μl input, 166 copies/10 μl input, and 43.7 copies/10 μl input, respectively. TORCH-S infection is one of the significant reasons for irregular pregnant outcomes. It is absolutely important to screen TORCH-S infection for women who had the histories of abnormal pregnancies to prevent birth defects and perinatal complications. This multiplex real-time PCR assay provides a rapid, sensitive, and specific technique to detect these six TORCH-S agents.

Use of Multiplex Polymerase Chain Reaction for Detection of High-Risk Human Papillomavirus Genotypes in Women Attending Routine Cervical Cancer Screening in Harare

Background/Aims: In Zimbabwe, cervical cancer is screened through cytology and visual inspection with acetic acid and cervicography (VIAC). The effectiveness of these methods can be increased if complemented by a human papillomavirus DNA detection tool since most cervical cancer cases are caused by persistent infection with high-risk human papillomavirus (HR-HPV) genotypes. Moreover, the possibility of multiple-genotype HR-HPV infections warrants the need for HPV detection tools with the capacity to detect both single and multiple infections. The aim of this study was to detect HR-HPV genotypes (HPV 16, 18, 31, 33, 35, 45, 51, 52, 56, and 58), using multiplex polymerase chain reaction (PCR), in stored cervicovaginal swabs from both HIV-positive and HIV-negative women reporting for routine cervical cancer screening. Methodology: Stored cervicovaginal swabs from sexually active women who underwent VIAC at the Parirenyatwa Referral Hospital in Harare, Zimbabwe, between February and April 2015 and had received HIV counselling and testing were genotyped for the selected 10 HR-HPV genotypes using in-house multiplex PCR. The results from the multiplex PCR were compared to those previously obtained when the same samples were HPV genotyped with next-generation sequencing (NGS) on an MiSeq platform (Illumina; USA). Results: A total of 136 women were recruited and all 10 HR-HPV genotypes were detected. Quality control failed in 3 of the 136 swabs during the multiplex PCR reactions. The prevalence of HR-HPV genotypes in the study subjects was 53% (70/133). HIV-infected women were 1.67 times more likely to be infected with HR-HPV than were HIV-negative women (OR 1.67; p = 0.17). Of the 70 HR-HPV-positive cases, 37% (26/70) had multiple HR-HPV infections, and the majority of them were HIV infected. HIV-infected women were 1.86 times more likely to have multiple HR-HPV infections than HIV-negative women (OR 1.86; p = 0.20). Multiplex PCR and NGS had an almost perfect concordance rate in ­HR-HPV detection (κ = 0.960), with only 3 discordant cases (negative with NGS and positive for HPV16 with multiplex PCR). Conclusion: Multiplex PCR can detect HR-HPV genotypes that are common in Zimbabwe and could be used to detect HR-HPV genotypes from women attending cervical cancer screening programs at the Parirenyatwa VIAC clinic in Harare.

Coronavirus and Chronic Lung Allograft Dysfunction: Hiding in Plain Sight?

Coronavirus and Chronic Lung Allograft Dysfunction: Hiding in Plain Sight?

Evaluation of the Influence of Gastrointestinal Coinfections on Rotavirus Vaccine Effectiveness in Botswana.

Studies have demonstrated reduced rotavirus vaccine effectiveness (VE) in resource-limited settings. Enteropathogen coinfections in rotavirus cases have been hypothesized to contribute to the lower VE in such settings. We sought to determine if coinfections affect rotavirus VE in Botswana. Between June 2013 and April 2015, children <60 months old, presenting with severe gastroenteritis at 4 hospitals as part of a national rotavirus surveillance were enrolled. Rotavirus enzyme immunoassay (EIA)-positive samples were tested with an in-house real-time polymerase chain reaction (PCR) panel that detected 9 pathogens and a commercial 15 multiplex PCR gastrointestinal pathogen panel. Coinfection was defined as detection of rotavirus plus 1 of the 5 pathogens with the highest attributable fractions for diarrhea. Vaccine status was compared between rotavirus case patients and non-rotavirus "test-negative" controls. VE was also calculated restricting cases to those with rotavirus as the only pathogen detected. Two hundred and forty-two children tested rotavirus EIA positive, and 368 children were negative. Of the 182 rotavirus EIA-positive samples tested with the gastrointestinal pathogen panel assay, coinfections were detected in 60 (33%). The overall adjusted 2-dose VE was 59% (95% confidence interval [CI]: 27-77) in the rotavirus coinfection group and 51% (95% CI: -14 to 79) in the rotavirus monoinfection subgroup. Using in-house multiplex PCR panel, of 213 rotavirus EIA-positive subjects, coinfections were detected in 98 samples (46%). The overall adjusted VEs for 2 doses were 48% (95% CI: -2 to 74) and 62% (95% CI: 25-80) in rotavirus monoinfection subgroup. We could not find evidence of an effect of enteric coinfections on the effectiveness of rotavirus vaccine.

A chip-based rapid genotyping assay to discriminate between rhinovirus species A, B and C

BackgroundHuman rhinoviruses (RVs) are increasingly associated with severe disease of the respiratory tract. Multiple studies highlighted the clinical significance of different RV species; RV-C is linked to asthma exacerbations and increased disease severity in children, whereas RV-B seems to correlate with milder disease. ObjectivesCurrent typing strategies for differentiation of RV species are time consuming and require extensive equipment. Here we present a novel genotyping tool to discriminate RV species A, B and C. Study designThe method encompasses a VP4/VP2 polymerase chain reaction (PCR), followed by hybridization of the product on a macro array with probes covering RV-A, B, and C, produced by Chipron as custom array. Validation was performed with respiratory specimens submitted for diagnostic evaluation to the Academic Medical Center. A selection of RV PCR-positive samples genotyped based on VP4/VP2 sequencing was evaluated. Diagnostic performance was tested on respiratory samples positive for RV in an in-house multiplex respiratory PCR from January 2016 to January 2017. In-house primers and additional genotype-specific primers were used for sequencing to investigate array-negative and array-double-positive samples. ResultsThe majority of samples pretyped RVs (n = 135) were classified correctly, except for one that was assigned RV-C instead of RV-A, and 3 samples tested negative. The array gave four double-positive results; the presence of more than one genotype was confirmed in two samples. In 173/187 (92.5%) RV-positive tested patient samples from 2016, the test resulted in a designated species. RV species A was identified in 109 specimens (58.3%), RV-B in 26 (13.9%), and RV-C in 56 (29.9%) samples. Sequencing of the probe region of 14 (7.6%) negative samples revealed up to 3 mismatches to the probes for 12 samples; in 2 cases no PCR product was generated. Notably, in 18 samples the chip detected more than one species, of which 16 were confirmed by sequencing. DiscussionThe Chipron LCD RV array provides a fast and highly sensitive method for discrimination between rhinovirus species, and has the power to detect dual infections.

The impact of virus infections on pneumonia mortality is complex in adults: a prospective multicentre observational study

BackgroundVarious viruses are known to be associated with pneumonia. However, the impact of viral infections on adult pneumonia mortality remains unclear. This study aimed to clarify the effect of virus infection on pneumonia mortality among adults stratified by virus type and patient comorbidities.MethodsThis multicentre prospective study enrolled pneumonia patients aged ≥15 years from September 2011 to August 2014. Sputum samples were tested by in-house multiplex polymerase chain reaction assays to identify 13 respiratory viruses. Viral infection status and its effect on in-hospital mortality were examined by age group and comorbidity status.ResultsA total of 2617 patients were enrolled in the study and 77.8% was aged ≥65 years. 574 (21.9%) did not have comorbidities, 790 (30.2%) had chronic respiratory disease, and 1253 (47.9%) had other comorbidities. Viruses were detected in 605 (23.1%) patients. Human rhinovirus (9.8%) was the most frequently identified virus, followed by influenza A (3.9%) and respiratory syncytial virus (3.9%). Respiratory syncytial virus was more frequently identified in patients with chronic respiratory disease (4.7%) than those with other comorbidities (4.2%) and without comorbidities (2.1%) (p = 0.037). The frequencies of other viruses were almost identical between the three groups. Virus detection overall was not associated with increased mortality (adjusted risk ratio (ARR) 0.76, 95% CI 0.53–1.09). However, influenza virus A and B were associated with three-fold higher mortality in patients with chronic respiratory disease but not with other comorbidities (ARR 3.38, 95% CI 1.54–7.42). Intriguingly, paramyxoviruses were associated with dramatically lower mortality in patients with other comorbidities (ARR 0.10, 95% CI 0.01–0.70) but not with chronic respiratory disease. These effects were not affected by age group.ConclusionsThe impact of virus infections on pneumonia mortality varies by virus type and comorbidity status in adults.

DNA Sequence Analysis of dtxR Gene (Partial) of Corynebacterium diphtheriae Causing Diphtheria in Jawa and Kalimantan Islands, Indonesia

BACKGROUND: dtxR gene is a global regulator that can be used as a marker for detection of Corynebacterium diphtheriae (C. diphtheriae) and it is also a representative tool for mapping purpose (molecular typing) of this bacteria. The aim of this study was to analyze the DNA sequences of partial dtxR gene of C. diphtheriae causing diphtheria in some region of Indonesia. DNA sequence analysis was used to verify the accuracy of the in-house multiplex polymerase chain reaction (PCR) method that used for detection of C. diphtheriae in the clinical specimen as well as a preliminary study to determine the strain diversity of C. diphtheriae circulating in Indonesia.METHODS:Ten PCR products targeting the dtxR gene that have been detected as positive C. diphtheriae previously by in-house multiplex PCR used as samples in this study. The DNA sequencing carried out by Sanger method and the sequence data was analyzed by Bioedit software offline and basic local alignment sequence typing (BLAST) online.RESULTS: All of DNA sequence analyzed in this study were similar or identical to the dtxR gene sequence data of C. diphtheriae registered in GenBank. Within the 162 nucleotides (base 150-311) of dtxR gene that analyzed, at least 2 clonals were found among 10 samples. Substitutions of 2 nucleotides (base 225 and 273) was detected, both were silent mutation.CONCLUSION:Ten partial DNA sequences of dtxR genes in this study verify the accuracy of in-house multiplex PCR which used to identify the bacteria causing diphtheria in the clinical specimen. The DNA sequences also represent the existing diversity of the bacteria causing diphtheria circulating in Indonesia.KEYWORDS: dtxR, C. diphtheriae, diphtheria, Indonesia

Performance of Xpert MTB/RIF on Ascitic Fluid Samples for Detection of Abdominal Tuberculosis.

Background:Diagnosis of abdominal tuberculosis (TB) from ascitic fluid samples using routinely available diagnostic methods is challenging due to its paucibacillary nature. Although performance of Xpert MTB/RIF assay has been evaluated extensively on pulmonary samples, its performance on extrapulmonary samples is still under evaluation.Objectives:The objective of this study was to find out the performance of Xpert MTB/RIF on ascitic fluid samples obtained from suspected cases of abdominal TB. Performance was compared with Mycobacterium growth indicator tube-960 (MGIT-960) culture and in-house multiplex polymerase chain reaction (PCR). The latter detects and differentiates Mycobacterium tuberculosis and nontuberculous mycobacteria simultaneously.Materials and Methods:Sixty-seven patients suspected of probable/possible abdominal TB were included in this observational, prospective study. All samples were tested by Ziehl–Neelsen staining, MGIT-960 culture, in-house multiplex PCR, and Xpert MTB/RIF assay.Results:All 67 samples were smear negative. Seventeen (25.4%) were MGIT-960 culture positive while 12 (17.9%) were detected positive by the Xpert MTB/RIF assay and 9 (13.4%) by in-house multiplex PCR. Sensitivity and specificity of the Xpert MTB/RIF assay compared with the MGIT-960 culture were 70.6% (95%, confidence interval [CI]: 44.1–89.7) and 100% (95%, CI: 92.8–100) and that of in-house multiplex PCR were 52.9% (95%, CI: 30.9–73.8) and 100% (95%, CI: 92.8–100), respectively.Conclusions:Diagnostic yield of Xpert MTB/RIF assay on ascitic fluid samples was lower than MGIT-960 culture. We thus emphasize on the need for urgent discovery of new biomarkers for paucibacillary TB.

Carbapenem-resistant Acinetobacter baumannii in Brazil: susceptibility profile and diversity of oxacillinases

ABSTRACT Introduction: The Acinetobacter calcoaceticus-baumannii (ABC) complex includes five species, and the A. baumannii is the most important of them because it carries mechanisms of carbapenems resistance, especially the oxacillinases. Objectives: The objectives of this study were to identify the species of the ABC complex, to evaluate the susceptibility profile and to investigate the presence of oxacillinases in carbapenems-resistant isolates from four Brazilian States. Methods: In the study period, 92 isolates from Rio Grande do Sul (RS), Rio de Janeiro (RJ), Parana (PR) and Sao Paulo (SP) were collected. The isolates were identified by matrix-assisted laser desorption ionization-time of fight mass spectrometry (MALDI-TOF MS) and sequencing of gyrB gene. Evaluation of susceptibility was performed by disk diffusion and broth microdilution. The presence of oxacillinases was performed by in-house multiplex polymerase chain reaction (PCR). Results: Ninety-one (99%) isolates were identified as A. baumannii by MALDI-TOF and sequencing. The majority of isolates (56; 61%) showed resistance to the six antimicrobial agents tested. Three isolates were resistant to polymyxin B [minimum inhibitory concentration (MIC) ≥ 4 µg/ml). Eighty (87%) isolates were positive to OXA-23-like, and twelve (13%) isolates to OXA-24-like. Conclusion: Our findings confirm the knowledge about the dissemination of the blaOXA-23 gene in Brazil and suggest the recent emergence and spread of blaOXA-24 gene, since it was identified in three of the four sampled states.

Evaluation of In-House Multiplex Polymerase Chain Reaction (MPCR) For Diagnosis of Pulmonary Tuberculosis

Evaluation of In-House Multiplex Polymerase Chain Reaction (MPCR) For Diagnosis of Pulmonary Tuberculosis

The carbapenem-resistant Enterobacteriaceae threat is growing: NDM-1 epidemic at a training hospital in Turkey.

BackgroundRecently, new carbapenemases in Enterobacteriaceae strains and non-fermentative gram-negative bacilli have been reported. The New Delhi metallo‐β‐lactamase-1 (NDM-1) is a major problem around the world. The purpose of this article is to address the NDM-1 Klebsiella pneumoniae epidemic detected in eight cases in our hospital.MethodsBacteria identified in this epidemic were from patients already admitted to the intensive care unit of the Sakarya University Training and Research Hospital during efforts toward establishment of infection surveillance and control program. Antimicrobial susceptibility testing of strains was performed using the VITEK 2 system (bioMérieux, France), E-test gradient strips (bioMérieux, France), and the disc diffusion test. For the metallo-beta-lactamase activity, the combined disc diffusion test and modified Hodge test as phenotypic tests were performed. To identify the resistance gene, the Xpert Carba-R kit (Cepheid Inc., USA) and an in-house multiplex polymerase chain reaction (PCR) method designed for five common carbapenemase genes (IMP, VIM, KPC, NDM-1, and OXA-48) were employed. The clonal relationship of these strains was explored by the repetitive PCR (rep-PCR, DiversiLab System, bioMérieux, France) method.ResultsDuring the December 2014 to March 2015 period, NDM-1 positive K. pneumoniae strains were detected in eight patients. All of these strains were found to produce NDM-1, while two of them also revealed the presence of OXA‐48. The rep-PCR results reveal a clonal proximity of 95 % for six of the eight strains.ConclusionsOur findings suggest the tendency of NDM-1-producing strains to spread in our country as well. A carbapenem-resistant K. pneumoniae threat may pose a great risk to our country. It is clear that more comprehensive infection control precautions should be implemented in our hospitals.

Carriage of Streptococcus pyogenes in primary school children: M-protein types, pyrogenic toxin genes, and investigation of the clonal relationships between the isolates

M-protein and pyrogenic toxins are the most important virulence factors of Streptococcus pyogenes, and they play significant role in the pathophysiology of acute rheumatoid fever and scarlet fever, respectively. In this study, the pharyngeal carriage of S.pyogenes of the primary school children, clonal relationship of the strains, M-protein types, and the presence of pyrogenic toxin genes were aimed to be investigated. A total of 668 throat cultures obtained from children (age range: 6-16 years) in two primary schools in our region, were included in the study. The clonal relationships of the isolated group A streptococci (GAS) strains were investigated by DiversiLab assay (BioMérieux, France), and the clonal relatedness was confirmed by pulsed-field gel electrophoresis (PFGE) method. M-protein (emm) typing was performed by DNA sequencing as suggested by Centers for Disease Control and Prevention (CDC). The genes encoding pyrogenic toxins, speA and speC, were investigated by an in-house multiplex polymerase chain reaction (PCR) method. S.pyogenes was isolated from 134 (20.05%) of the throat samples. The GAS carriage rate of the students aged ≥10 was statistically higher than those 7-9 years age group (%22 vs %16.4, p<0.05). The M protein gene could be characterized only among 123 isolates by DNA sequencing, and 20 different emm types were detected. The most frequent emm type was emm1 (n=38, 30.9%) followed by emm12 (n=18, 14.6%), emm89 (n=10, 8.1%), emm118 (n=9, 7.3%), and emm4 (n=7, 5.7%). Pyrogenic toxin genes were found in 25 (18.6%) of the isolates, including speA in 11 isolates (8.2%) and speC in 12 isolates (8.9%) and both genes were detected in 2 isolates (1.5%). Sixty-two different Rep (Repetitive extragenic palindromic)-PCR profiles were detected in 134 S.pyogenes isolates by DiversiLab method. Thirteen different clusters were formed by a total of clonally related 36 isolates revealing a strain clustering ratio of 26.9%. Clonal relationship of all isolates in the same cluster was confirmed by PFGE method. In this study, relatively high percentage of GAS carriage was observed among primary school children in our region. The coverage rate of the 30-valent vaccine was determined to be over 90% with respect to M-protein types. Since the pyrogenic toxin-encoding genes were found in one fifth of the isolates from the studied subjects, we concluded that the carrier population may also have high risk for scarlet fever. We also concluded that, the clonal relationship ratio determined among the isolates may be a risk in school transmission of GAS.

Etiology and antimicrobial susceptibility of pathogens responsible for urethral discharge among men in Harare, Zimbabwe.

Periodic etiological surveillance of sexually transmitted infection (STI) syndromes is required to validate treatment algorithms used to control STIs. However, such surveys have not been performed in Zimbabwe over the past decade. A cross-sectional study design was used to determine the prevalence of the key STI etiological agents causing male urethral discharge (MUD). Urethral swab specimens were collected for molecular analysis and Neisseria gonorrhoeae isolation from consenting men 18 years and older who presented with MUD to the 12 clinics in Harare, Zimbabwe, between November 2010 and May 2011. A validated in-house multiplex polymerase chain reaction assay was used to detect the presence of N. gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, and Mycoplasma genitalium. Gonococci were cultured on selective media, and antimicrobial susceptibilities were determined locally for ciprofloxacin, kanamycin, ceftriaxone, and cefixime using Etest strips, and minimum inhibitory concentrations were reported using defined breakpoints. Among 130 participants, N. gonorrhoeae was the most frequent pathogen detected (106; 82.8%), followed by C. trachomatis (15; 11.7%), M. genitalium (6; 4.7%), and T. vaginalis (2; 1.6%). Four (6.1%) of the 66 gonococci isolated were resistant to fluoroquinolones, whereas all viable isolates were susceptible to kanamycin, cefixime, and ceftriaxone. Gonorrhea is the most important cause of MUD in men in Harare, and our study highlights the emergence of fluoroquinolone-resistant N. gonorrhoeae. Further STI surveys are required in other regions of Zimbabwe to obtain a nationally representative picture of gonococcal burden and antimicrobial resistance among MUD patients.

Doğu Karadeniz Bölgesi Hepatit C Hastalarında Hepatit C Virusu Genotiplerinin Belirlenmesi

Hepatitis C virus (HCV), the major cause of transfusion-associated hepatitis, is an important public health problem in the world as well as in Turkey. HCV is grouped as six distinct genotypes and a large number of closely-related subtypes. Genotyping of HCV is an important tool for providing epidemiological data, prediction of prognosis, and optimization of antiviral therapy. This study was carried out to determine the distribution of HCV genotypes in hepatitis C patients residing in different provinces of the Eastern Black Sea Region, Turkey. A total of 304 HCV-RNA positive cases (151 male, 153 female; age range: 11-93 years, mean age: 55.2 ± 13.3 years) who were admitted to the Molecular Microbiology Unit of Department of Medical Microbiology, Karadeniz Technical University Faculty of Medicine, between January 2009 to December 2012, were included in the study. HCV genotypes were detected in plasma samples of the patients by using commercial assays [INNO-LiPA HCV II (Innogenetics, Belgium) or Abbott RealTime HCV Genotype II (Abbott Molecular Inc, USA)]. Due to the ambiguous genotyping results in some samples with these methods, an in-house multiplex polymerase chain reaction (PCR) assay with genotype-specific primers was also used in the study. Similar to the previous reports from Turkey, our results showed that four HCV genotypes (1, 2, 3, and 4) prevailed in the Eastern Black Sea Region and the predominant genotype and subtype were genotype 1 (92.8%) and 1b (87.5%), respectively. Distribution of genotypes were observed to vary according to the province. Prevalences of subtype 1a, genotype 2, 3, and 4 were noted as 5.3%, 1.6%, 4.9%, and 0.7%, respectively. Furthermore, the samples from Giresun, Gumushane and Bayburt provinces, which are relatively less immigrated, had higher genotype 1, and the prevalence rates in the region was affected by the presence of non-citizen residents. This study is the first report on distribution of HCV genotypes in chronic hepatitis C patients living in the provinces of Eastern Black Sea Region. Moreover, genotype-specific multiplex PCR assay could be useful in resolving certain methodological problems such as "ghost bands" encountered in line probe assay (LiPA) and multiple genotypes (including genotype 4) observed in real-time PCR during the characterization of HCV genotypes seen in Turkey.

Genotyping of HPA‐1 to ‐7 and ‐15 in the Thai population using multiplex PCR

Different polymerase chain reaction (PCR) techniques for human platelet antigens (HPA) genotyping have been implemented, in order to diagnose the clinical syndromes of patients with thrombocytopaenia and provide effective HPA-matched platelet donors. The aim of this study is to develop an in-house multiplex PCR for HPA-1 to -7 and -15 genotyping in the Thai population. One hundred DNA samples of known HPA genotyping by the PCR with sequence-specific primers (PCR-SSP), as previously described, were tested with the multiplex PCR. Additionally, 300 DNA samples of group O donors were tested for HPA-1 to -7 and -15 genotyping using multiplex PCR. The comparison of HPA-1 to -7 and -15 genotype results between multiplex PCR and PCR-SSP technique was in 100% concordance. Interestingly, HPA-2b2b genotype was found in two samples; however, other low-incidence genotypes such as HPA-1b1b, HPA-5b5b, HPA-6b6b and HPA-7b7b were not found in this study. Moreover, 30 samples were randomly tested twice for HPA genotyping using the multiplex PCR and demonstrated reproducible results. This study shows that the in-house multiplex PCR is simple, cost-effective and suitable for HPA genotyping for routine laboratories in other developing countries. Nevertheless, a large-scale evaluation of this technique through multicentre analysis is suggested.

Is the new variant of Chlamydia trachomatis present in South Africa?

An investigation was conducted to determine the prevalence of the new variant of Chlamydia trachomatis (nvCT) in South Africa (SA). Four hundred and fifty-nine C. trachomatis-positive clinical specimens, tested by in-house multiplex polymerase chain reaction (PCR), were screened for the presence of the 377 bp deletion in the ORF1 of the cryptic plasmid, documented in nvCT, by means of nested PCR. All specimens generated a 630 bp amplicon in the nested PCR, indicative of wild-type CT, and no nvCT strains were identifed. Even though there was no evidence of the presence of nvCT in South Africa, continuous screening for emerging mutant strains is of epidemiological importance.

A Fast Real-Time Polymerase Chain Reaction Method for Sensitive and Specific Detection of the Neisseria gonorrhoeae porA Pseudogene

Ever since the advent of molecular methods, the diagnostics of Neisseria gonorrhoeae has been troubled by false negative and false positive results compared with culture. Commensal Neisseria species and Neisseria meningitidis are closely related to N. gonorrhoeae and may cross-react when using molecular tests comprising too-low specificity. We have devised a real-time polymerase chain reaction (PCR), including an internal amplification control, that targets the N. gonorrhoeae porA pseudogene. DNA was automatically isolated on a BioRobot M48. Our subsequent PCR method amplified all of the different N. gonorrhoeae international reference strains (n = 34) and N. gonorrhoeae clinical isolates (n = 176) but not isolates of the 13 different nongonococcal Neisseria species (n = 68) that we tested. Furthermore, a panel of gram-negative bacterial (n = 18), gram-positive bacterial (n = 23), fungal (n = 1), and viral (n = 4) as well as human DNA did not amplify. The limit of detection was determined to be less than 7.5 genome equivalents/PCR reaction. In conclusion, the N. gonorrhoeae porA pseudogene real-time PCR developed in the present study is highly sensitive, specific, robust, rapid and reproducible, making it suitable for diagnosis of N. gonorrhoeae infection.