Diagnostic Microbiology and Infectious Disease via MedWorm.com

Development of an ultrasensitive polymerase chain reaction–amplified immunoassay based on mycobacterial RD antigens: implications for the serodiagnosis of tuberculosis

Diagnostic Microbiology and Infectious Disease — Thu, 19 Jan 2012 03:02:10 +0100

Abstract: Immuno-polymerase chain reaction (I-PCR) combines the versatility of enzyme-linked immunosorbent assay (ELISA) with the exponential amplification power of PCR. The present study was designed to detect antibodies to Mycobacterium tuberculosis complex–specific region of difference (RD) antigens, i.e., early secretory antigenic target-6, culture filtrate protein-10, culture filtrate protein-21, and mycobacterial protein from species tuberculosis-64, as well as antigens in pulmonary tuberculosis patients by I-PCR assay. We could detect ESAT-6 and other RD antigens up to 0.1 fg by I-PCR assay, thus resulting in 107 times higher sensitivity than that observed with ELISA. With paired sample analysis based on the detection of antibodies in serum and antigens in sputum of the same indiv...

Diagnostic significance of hepatitis B viral antigens in patients with glomerulonephritis-associated hepatitis B virus infection

Diagnostic Microbiology and Infectious Disease — Thu, 19 Jan 2012 03:02:10 +0100

Abstract: Hepatitis B viral infection can lead to hepatitis B virus–associated glomerulonephritis, a clinically significant subtype of secondary nephritis. In the present study, we examined the presence of PreS1/S2 antigen in renal tissues by use of immunohistochemistry and investigated the use of PreS1/S2 and 2 HBV serum antigens, HBe-Ag and HBs-Ag, in the diagnosis. We assessed the presence of these 3 antigens in patients with confirmed hepatitis B virus–associated glomerulonephritis (n = 22) and patients without this disease (n = 19). Our results indicate that the combined use of PreS1/S2-Ag and serum HBe-Ag in the diagnosis of hepatitis B virus–associated glomerulonephritis had good positive predictive value (0.89), modest negative predictive value (0.77), and substantial agreeme...

Evaluation of a novel commercial rapid test for dengue diagnosis based on specific IgA detection

Diagnostic Microbiology and Infectious Disease — Thu, 19 Jan 2012 03:02:10 +0100

Abstract: The performance of the novel commercial test ASSURE® Dengue IgA Rapid test (MP Diagnostics) was evaluated using a panel of 172 sera collected from dengue patients and 47 sera from healthy blood donors. The overall specificity and sensitivity were 61.0% and 85.1%, respectively. However, the positivity rate for IgA went from 33.3% for sera collected the same day of fever onset to 81.2% for sera collected 5 days after fever onset. Infections with serotype 2 viruses were detected more efficiently than those with serotype 1 viruses, and no sera from infections with serotypes 3 and 4 were available. In addition, the kit was twice more efficient at detecting secondary infections than at detecting primary infections. Finally, the ASSURE® test showed good repeatability and reproducibili...

Pyrosequencing-based validation of a simple cell-suspension polymerase chain reaction assay for Campylobacter with application of high-processivity polymerase and novel internal amplification controls for rapid and specific detection

Diagnostic Microbiology and Infectious Disease — Thu, 19 Jan 2012 03:02:10 +0100

We present a specific protocol which eliminates the need for time-consuming and expensive genomic DNA extractions and, using a high-processivity polymerase, demonstrate conclusive screening of samples in 99%) sensitive, and spike-back experiments demonstrated a detection threshold of (Source: Diagnostic Microbiology and Infectious Disease)

Detection of 10 medically important Candida species by seminested polymerase chain reaction

Diagnostic Microbiology and Infectious Disease — Mon, 12 Dec 2011 05:00:00 +0100

Abstract: A seminested PCR detecting ten medically important Candida species were achieved. Analytical sensitivity and specificity were not compromised. (Source: Diagnostic Microbiology and Infectious Disease)

Low prevalence of Pneumocystis jirovecii lung colonization in Ugandan HIV-infected patients hospitalized with non-Pneumocystis pneumonia

Diagnostic Microbiology and Infectious Disease — Wed, 07 Dec 2011 05:00:00 +0100

Abstract: Pneumocystis jirovecii is an important opportunistic infection in human immunodeficiency virus (HIV)–infected patients. In the developed world, P. jirovecii epidemiology is marked by frequent colonization in immunosuppressed patients, but data on the prevalence of colonization are very limited in sub-Saharan Africa, where the majority of persons living with HIV reside. Our objective was to describe the epidemiology of P. jirovecii colonization among HIV-positive patients in a cross-sectional, hospital-based study of patients admitted with suspected pneumonia in Kampala, Uganda. P. jirovecii was detectable in bronchoalveolar lavage fluid from 7 (6%) of 124 consecutive patients with non-Pneumocystis pneumonia. Colonization was not associated with patient demographic or clinical i...

Nontuberculous mycobacterial infections in cancer patients in a medical center in Taiwan, 2005–2008

Diagnostic Microbiology and Infectious Disease — Mon, 05 Dec 2011 05:00:00 +0100

In conclusion, physicians need to be aware of the possibility of co-existing pulmonary NTM infection in patients with lung cancer. In addition, disseminated NTM infection should be considered in patients with hematologic cancer. (Source: Diagnostic Microbiology and Infectious Disease)

Validation of a polymerase chain reaction–oligochromatography test for detection of influenza A (H1N1) 2009 virus

Diagnostic Microbiology and Infectious Disease — Mon, 05 Dec 2011 05:00:00 +0100

Abstract: The outbreak of pandemic influenza A (H1N1) 2009 virus caused the first influenza pandemic disease of the 21st century. In August 2010, the pandemic moved into the post-pandemic period. However, localized outbreaks of various magnitudes continued with a higher rate of disease severity. The aim of this study was to assess a new polymerase chain reaction (PCR)–oligochromatographic assay (Speed-Oligo) in the diagnosis of novel influenza A (H1N1) 2009. A total of 405 nasopharyngeal aspirate specimens from 400 pediatric and adults patients with suspected infection of pandemic influenza A (H1N1) 2009 were analyzed. The sensitivity and specificity values of the Speed-Oligo assay in comparison to reverse transcriptase–PCR assay developed by the Centers for Disease Control and Prevent...

Methicillin-resistant Staphylococcus aureus expressing low-level methicillin resistance may not be detected by the VITEK2® system

Diagnostic Microbiology and Infectious Disease — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Low-level methicillin-resistant Staphylococcus aureus may be difficult to detect with the VITEK® 2 system (VK2). Here, we suggest that S. aureus exhibiting VK2-oxacillin MIC of 1 or 2 mg/L and a negative cefoxitin screen should be tested for the presence of mecA or its gene product. (Source: Diagnostic Microbiology and Infectious Disease)

Clinical evidence for rapid transmission of Lyme disease following a tickbite

Diagnostic Microbiology and Infectious Disease — Mon, 21 Nov 2011 05:00:00 +0100

We describe 3 cases in which transmission of Borrelia burgdorferi, the spirochetal agent of Lyme disease, appears to have occurred in less than 24 h based on the degree of tick engorgement, clinical signs of acute infection, and immunologic evidence of acute Lyme disease. Health care providers and individuals exposed to ticks should be aware that transmission of Lyme disease may occur more rapidly than animal models suggest. A diagnosis of Lyme disease should not be ruled out based on a short tick attachment time in a subject with clinical evidence of B. burgdorferi infection. (Source: Diagnostic Microbiology and Infectious Disease)

Coccidioidomycosis of cervical lymph nodes in an HIV-infected patient with immunologic reconstitution on potent HAART: a rare observation in a nonendemic area

Diagnostic Microbiology and Infectious Disease — Mon, 21 Nov 2011 05:00:00 +0100

We report a case of coccidioidomycosis of cervical lymph nodes that occurred early after the introduction of highly active antiretroviral therapy during the phase of immune system recovery, demonstrating a rare disease in a nonendemic area. (Source: Diagnostic Microbiology and Infectious Disease)

Fulminant gestational hepatitis due to primary herpes simplex type 2 infection: use of serum HSV polymerase chain reaction for noninvasive diagnosis

Diagnostic Microbiology and Infectious Disease — Mon, 21 Nov 2011 05:00:00 +0100

We present the first reported case of primary HSV type 2 hepatitis in a pregnant woman who was diagnosed by detection of HSV-2 viremia via real-time polymerase chain reaction. The patient was successfully treated with acyclovir and delivered a healthy infant. (Source: Diagnostic Microbiology and Infectious Disease)

Evaluation of 3 different rapid automated systems for diagnosis of urinary tract infections

Diagnostic Microbiology and Infectious Disease — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Urinary tract infections (UTI) are one of the most common infections in both hospitalised and ambulant patients. Rapid diagnostic of UTIs is necessary to provide early information about the presence of bacteria and the indication to administer an antibiotic therapy. Here we report on a study comparing 3 different rapid automated systems with the semiquantitative plate culture reference method in a university hospital with a highly complex patient population. In total, 2230 urine samples were consecutively tested using the UroQuick (Alifax), the BACSYS-40i (Sysmex), and the UF-1000i (Sysmex) system. In comparison to the results obtained by culture techniques, the automated systems showed a sensitivity of 73.0–80.9% and a specificity ranging between 61.8% and 92.8%. Additionally,...

Pelvic abscess caused by New Delhi metallo-β-lactamase-1–producing Klebsiella oxytoca in Taiwan in a patient who underwent renal transplantation in China

Diagnostic Microbiology and Infectious Disease — Fri, 18 Nov 2011 05:17:01 +0100

Enterobacteriacae species harboring New Delhi metallo-β-lactamase 1 (NDM-1) have spread worldwide (). A 56-year-old man, who underwent renal transplantation in a hospital in Nanchang, Province of Jangxi in China in 2010, presented to a hospital in Taiwan 7 days after transplantation with abdominal pain and dysuria. On admission, the patient was afebrile (36.1 °C). Magnetic resonance imaging (MRI) of the pelvis revealed a large (13 × 5 cm) abscess in the anterior pelvic cavity (). Bacterial culture of the aspirated fluid grew ertapenem-resistant Klebsiella oxytoca. Neither anal nor throat swab cultures yielded ertapenem-resistant K. oxytoca using eosin methylene blue agar with ertapenem disk (10 μg) as screening media. Tigecycline (70 mg loading and 50 mg every 12 h) was administered. T...

Tuberculosis patients are characterized by a low–IFN-γ/high–TNF-α response to methylated HBHA produced in M. smegmatis

Diagnostic Microbiology and Infectious Disease — Fri, 18 Nov 2011 05:17:01 +0100

Abstract: Whole blood from Mycobacterium tuberculosis–infected subjects was stimulated with heparin-binding hemagglutinin (HBHA). Tuberculosis (TB) patients showed an HBHA-specific T-cell response characterized by low–IFN-γ/high–TNF-α secretion, while asymptomatic subjects with latent infection (LTBI) and TB patients under therapy showed a pattern with high IFN-γ/low TNF-α. These results underscore the usefulness of HBHA in helping to distinguish LTBI subjects versus TB patients. (Source: Diagnostic Microbiology and Infectious Disease)

Fusarium verticillioides fungemia in a liver transplantation patient: successful treatment with voriconazole

Diagnostic Microbiology and Infectious Disease — Fri, 18 Nov 2011 05:17:01 +0100

We present a rare case of F. verticillioides fungemia that occurred in a patient who underwent a second orthotopic liver transplantation for chronic rejection and completely responded to treatment with voriconazole. (Source: Diagnostic Microbiology and Infectious Disease)

Wild-type MIC distribution and epidemiological cut-off values in clinical Legionella pneumophila serogroup 1 isolates

Diagnostic Microbiology and Infectious Disease — Fri, 18 Nov 2011 05:00:00 +0100

Conclusion: All isolates were inhibited by low concentrations of the fluoroquinolones and macrolides tested, with somewhat higher MICs for the fluoroquinolones. Rifampicin was found to be the most active against L. pneumophila isolates in vitro. These data can be used as a reference for the detection of resistance in clinical L. pneumophila isolates and as a setting of clinical breakpoints. (Source: Diagnostic Microbiology and Infectious Disease)

Characteristics related to antimicrobial resistance and biofilm formation of widespread methicillin-resistant Staphylococcus epidermidis ST2 and ST23 lineages in Rio de Janeiro hospitals, Brazil

Diagnostic Microbiology and Infectious Disease — Fri, 18 Nov 2011 05:00:00 +0100

In this study, staphylococcal chromosomal cassette mec (SCCmec) types, antimicrobial susceptibility profiles, biofilm formation genes, and multilocus sequence types (MLST) were investigated in 35 MRSE clinical isolates. The collection of isolates was previously well characterized by pulsed-field gel electrophoresis (PFGE) into 2 main genotypes (A and B, 22 isolates) and 10 sporadic genotypes (13 isolates). MLST revealed a total of 8 different sequence types (STs), but ST2 and ST23, which were icaAB-positive, represented the majority (71.4%) of MRSE isolates tested. Almost all isolates (91.4%) belonged to clonal complex 2. SCCmec types III and IV were identified among 71.4% of the isolates, while the remaining was nontypeable. The predominant MRSE genotypes were defined as SCCmec type III/S...

Evaluation of the performance of 5 commercialized enzyme immunoassays for the detection of Taenia solium antibodies and for the diagnosis of neurocysticercosis

Diagnostic Microbiology and Infectious Disease — Wed, 16 Nov 2011 05:00:00 +0100

This study aimed to evaluate 5 enzyme immunoassays for detecting human antibodies against Taenia solium in human serum and for the diagnosis of neurocysticercosis (NCC): DRG™, RIDASCREEN™, NOVATECH™, CYPRESS™, and IVD™. A collection of 114 reference serum samples were used. All sera were tested both by ELISA and by an immunoblot method (enzyme-linked immunoelectrotransfer blot [EITB]). When compared with EITB, the Ridascreen™ test had the best positive concordance rate (85.1–91.2%) and the NovaLisa test™ showed the optimal negative concordance rate (93.7–95.6%). All tests had a sensitivity under 72% and a specificity above 60%. The best sensitivity was obtained using Ridascreen™ test (71.4%). An optimal specificity was achieved by the NovaLisa test™. T. solium–posit...

Detection of immune cell response to M. tuberculosis–specific antigens by quantitative polymerase chain reaction

Diagnostic Microbiology and Infectious Disease — Wed, 16 Nov 2011 05:00:00 +0100

Abstract: One third of the world's population is latently infected with Mycobacterium tuberculosis (Mtb) and up to 10% of infected individuals develop active tuberculosis (TB) in their lifetime. Among the major challenges in the control of TB is the implementation of sensitive methods for detection of latent tuberculosis infection (LTBI). Currently, in vitro interferon gamma release assays, yielding single value readout, are used as an alternative to the traditional tuberculin skin test for the diagnosis of LTBI. More complex characterization of immune status of LTBI individuals, however, is desirable for indication of LTBI subjects for preventative chemotherapy. Here we describe a quantitative polymerase chain reaction (qPCR) for determination of expression levels of 14 genes, additional ...

Molecular diagnosis and species identification of imported malaria in returning travellers in Italy