PubMed Health⌕ Search

Biomedical subjects

Haijing Li

Publications and source records attributed to Haijing Li.

18 recordsLinked to original sources
PubMed2006

Antimicrobial susceptibility patterns and staphylococcal cassette chromosome mec types of, as well as Panton-Valentine leukocidin occurrence among, methicillin-resistant Staphylococcus aureus isolates from children and adults in middle Tennessee.

Antimicrobial susceptibility patterns, Panton-Valentine leukocidin (PVL) occurrence, and staphylococcal cassette chromosome mec (SCCmec) types in methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from children and adults at Vanderbilt University Medical Center during a 12-month period were evaluated. A total of 1,315 MRSA isolates were collected, of which 748 (36.7%) were recovered from children. Among all isolates, 448 (34.1%) were SCCmec-II, and 847 (64.4%) were SCCmec-IV. More SCCmec-IV isolates were recovered from children than SCCmec-II isolates (424 [50.1%] versus 50 [11.2%]; odds ration [OR]=7.98; P<0.000001). The PVL gene was detected in 93.6% of SCCmec-IV isolates, in contrast to 0.2% in SCCmec-II isolates. Within SCCmec-IV isolates, a statistically higher PVL occurrence was noticed in children (98.1%) than in adults (89.1%) (OR=6.34; P<0.000001). Overall, SCCmec-II strains showed greater resistance than SCCmec-IV strains to clindamycin, erythromycin, levofloxacin, gentamicin, rifampin, minocycline, and trimethoprim-sulfamethoxazole. Both SCCmec-II and SCCmec-IV strains recovered from adults were more resistant to these antibiotics than those recovered from children. SCCmec-II strains were predominantly recovered from the respiratory tract, whereas SCCmec-IV strains were predominantly recovered from skin, soft tissue, abscesses, and surgical wounds. These data indicate that SCCmec-IV MRSA isolates frequently infect children in middle Tennessee and are likely to harbor the PVL gene.

Adult↗
PubMed2006

Urine polymerase chain reaction is not as sensitive as urine antigen for the diagnosis of disseminated histoplasmosis.

We developed a colorimetric microtiter plate polymerase chain reaction enzyme immunoassay (PCR-EIA) for the detection of Histoplasma capsulatum in urine. The specificity of the PCR assay was confirmed using H. capsulatum (positive control) and Blastomyces dermatitidis (negative control) isolates. The analytical sensitivity of the PCR assay was determined by testing urine samples spiked with freshly grown H. capsulatum organisms and was 2 yeasts per reaction in urine and 0.2 yeasts per reaction in urine sediment after centrifugation. Fifty-one urine specimens positive for H. capsulatum antigen and 25 urine specimens from healthy volunteers were tested blindly. Patient specimens also were cultured for H. capsulatum. The PCR assay was positive in 4 (7.8%) of 51 urine specimens containing antigen and negative in urine specimens from healthy volunteers. The positive PCR results occurred in 4 of 5 urine specimens that were positive by culture, and each exhibited high level of antigenuria (>20 U). Urine cultures were not positive in 24 urine specimens with an antigenuria of 1-19.9 U, but were positive in 5 of 27 urine specimens with antigenuria >20 U. Thus, positive PCR results in urine specimens correlate with positive culture results, but not with antigenuria. The low sensitivity of this PCR assay in urine limits its use in the diagnosis of disseminated histoplasmosis.

Antigens, Fungal↗
PubMed2006

Invader plus method detects herpes simplex virus in cerebrospinal fluid and simultaneously differentiates types 1 and 2.

We report here on the development and validation of a prototype Invader Plus method for the qualitative detection of herpes simplex virus types 1 and 2 in cerebrospinal fluid (CSF). The method combines PCR and Invader techniques in a single, closed-tube, continuous-reaction format that gives an analytical sensitivity of approximately 10 copies per reaction. The clinical sensitivity and specificity were 100.0% and 98.6%, respectively, when the results of the method were validated against the results obtained with a PCR colorimetric microtiter plate system by use of clinical CSF specimens.

Central Nervous System Viral Diseases↗
PubMed2006

Clonal spread of serogroup W135 meningococcal disease in Turkey.

Six cases of Neisseria meningitidis serogroup W135 meningococcal infection have been reported in Turkey since 2003. Seven isolates recovered from four meningococcal meningitis patients and two asymptomatic carriers produced three distinct pulsed-field gel electrophoresis (PFGE) patterns. Multilocus sequence typing and antigen gene sequencing showed that five isolates were indistinguishable from ST-11 (ET-37) serogroup W135 meningococci, which were first isolated in Saudi Arabia and were responsible for the worldwide outbreak among Hajj pilgrims and their contacts in 2000. The remaining two isolates, which had related PFGE patterns, differed from each other at only one of the genetic loci characterized but were not related to the ST-11 clonal complex. None of the six individuals recalled contact with a pilgrim or had traveled on the Hajj. These six individuals exhibited no time or place relationships to each other, except for the two asymptomatic carriers, who were soldiers and served in the same military unit. These data demonstrate that serogroup W135 meningococci with different genotypes, including the Hajj epidemic strain, are endemic in Turkey.

Bacterial Typing Techniques↗
PubMed2005

QIAamp MinElute virus kit effectively extracts viral nucleic acids from cerebrospinal fluids and nasopharyngeal swabs.

BACKGROUND: Nucleic acid preparation from a variety of clinical specimens requires efficient target recovery and amplification inhibitor removal and is critical for successful molecular diagnosis. The QIAamp MinElute Virus kit (Qiagen Inc., Valencia, CA) was compared to the two existing methods currently used in our laboratory, IsoQuick (Orca Research Inc., Bothell, WA) for DNA extraction and RNAzol B (Leedo Laboratories Inc., Houston, TX) for RNA extraction, of viral nucleic acids. STUDY DESIGN: A total of 150 clinical specimens, including cerebrospinal fluid (CSF) and nasopharyngeal swabs (NPS), were used to determine the extraction efficiency of the MinElute compared to the other two methods. Nucleic acid recovery, hands-on time, turn-around-time and cost were compared across all kits. RESULTS: There was complete concordance between the MinElute and IsoQuick/RNAzol kits when herpes simplex virus (HSV), Epstein-Barr virus (EBV), varicella-zoster virus (VZV), influenza A virus or enteroviruses were detected using a colorimetric microtiter plate PCR system. The kits were equivalent in their ability to detect either DNA or RNA with superior ability to recover a high quality and quantity of RNA. With the potential to process larger specimen volumes, the MinElute kit can significantly shorten processing time from 2h to 50-55min. CONCLUSIONS: Although relatively high test kit costs were noted, the MinElute kit provides another rapid and user-friendly specimen processing tool in the diagnostic molecular microbiology laboratory.

Cerebrospinal Fluid↗
PubMed2005

Comparative evaluation of three commercial systems for nucleic acid extraction from urine specimens.

A nucleic acid extraction system that can handle small numbers of specimens with a short test turnaround time and short hands-on time is desirable for emergent testing. We performed a comparative validation on three systems: the MagNA Pure compact system (Compact), the NucliSens miniMAG extraction instrument (miniMAG), and the BioRobot EZ1 system (EZ1). A total of 75 urine specimens submitted for polyomavirus BK virus detection were used. The human beta-actin gene was detected on 75 (100%), 75 (100%), and 72 (96%) nucleic acid extracts prepared by the miniMAG, EZ1, and Compact, respectively. The miniMAG produced the highest quantity of nucleic acids and the best precision among the three systems. The agreement rate was 100% for BKV detection on nucleic acid extracts prepared by the three extraction systems. When a full panel of specimens was run, the hands-on time and test turnaround time were 105.7 and 121.1 min for miniMAG, 6.1 and 22.6 min for EZ1, and 7.4 and 33.7 min for Compact, respectively. The EZ1 and Compact systems processed automatic nucleic acid extraction properly, providing a good solution to the need for sporadic but emergent specimen detection. The miniMAG yielded the highest quantity of nucleic acids, suggesting that this system would be the best for specimens containing a low number of microorganisms of interest.

Actins↗
PubMed2004

Detection of hepatitis C virus by a user-developed reverse transcriptase-PCR and use of amplification products for subsequent genotyping.

BACKGROUND: Detection, quantitation and genotyping of hepatitis C virus (HCV) are important in selecting appropriate therapy. Current commercially available HCV genotyping kits, including sequencing-based TRUGENE HCV 5'NC and hybridization-based INNO-LiPA HCV II assays, rely on amplification products (amplicons) generated by HCV reverse-transcriptase (RT)-PCR methods such as the Roche AMPLICOR HCV test. METHODS: We developed a one-step RT-PCR assay to amplify and detect HCV RNA, and the resulting amplicons were used for HCV genotyping (TRUGENE). A total of 142 clinical samples were used to compare results from the RT-PCR/TRUGENE assay and those generated by the COBAS AMPLICOR and INNO-LiPA tests. RESULTS: Eighty-seven of 108 plasma specimens which were positive by AMPLICOR were also positive by the user-developed RT-PCR, giving a sensitivity of 100.0%. The RT-PCR detected 2 of 21 AMPLICOR-negative specimens and none of 34 HCV-EIA-negative serum specimens, giving a specificity of 96.4%. The 87 amplicons from the RT-PCR yielded HCV genotypes. HCV genotype results from both TRUGENE and INNO-LiPA were all in agreement. The TRUGENE and INNO-LiPA assays identified 69 (79.3%) and 47 (54.0%) specimens, respectively at the subtype level. HCV subtype information agreed by both assays in 34 of 36 (99.4%) specimens. One specimen with HCV genotypes 2 and 4 by INNO-LiPA was classified as a single genotype 2 by TRUGENE. CONCLUSION: Our data showed that the user-developed RT-PCR has comparable sensitivity and specificity for the detection of HCV in clinical specimens. The amplicons generated by the RT-PCR can be used for HCV genotyping by the sequencing-based TRUGENE assay.

Base Sequence↗
PubMed2003

Cytokine expression in respiratory syncytial virus-infected mice as measured by quantitative reverse-transcriptase PCR.

In the murine model for respiratory syncytial virus (RSV) infection, cytokine patterns induced by vaccinations with either killed (i.e. formalin-inactivated, alum-precipitated) virus (KV) or live virus (LV) have been shown to influence disease expression. To determine the mRNA expression of the cytokines IL-4 and IFN-gamma in BALB/c mice challenged with RSV, a real-time quantitative reverse-transcriptase PCR assay was developed. This assay uses 5'-exonuclease fluorogenic probes and is performed on the ABI PRISM 7700 Sequence Detector System (TaqMan). The relative quantitative levels of mRNA for IL-4 and IFN-gamma were compared with those measured by an RNase protection assay (RPA) and an enzyme immunoassay (EIA), which are methods used to measure the levels of mRNA and protein, respectively. Results obtained by the TaqMan assay showed that mice primed with KV induces increased IL-4 mRNA production while LV induces increased IFN-gamma mRNA, which is in agreement with conventional methods. IL-4 and IFN-gamma relative quantities obtained from TaqMan were highly correlated to those determined by RPA (r=0.96 for IFN-gamma, P<0.01) and EIA (r=0.90 for IL-4 and r=0.75 for IFN-gamma, P<0.01). Assay reproducibility was examined by testing a same sample in triplicate at three experiments. Minimal deviation values were observed in both intra- and inter-assays. TaqMan, which is rapid, sensitive and reproducible, provides an alternative tool for the quantitative analysis of cytokine mRNA expression in the murine model of RSV immunopathogenesis.

Animals↗
PubMed2003

Identification of the bacterial etiology of culture-negative endocarditis by amplification and sequencing of a small ribosomal RNA gene.

We report two cases of culture-negative bacterial endocarditis in which the organisms were identified by amplification and sequencing of the bacterial 16S rRNA gene. These results support an important role for polymerase chain reaction followed by direct sequencing to determine the etiology of culture-negative bacterial endocarditis and to guide appropriate antimicrobial therapy.

Adult↗
PubMed2003

Measurement of human cytomegalovirus loads by quantitative real-time PCR for monitoring clinical intervention in transplant recipients.

Quantitative monitoring of human cytomegalovirus (HCMV) infection is helpful in determining appropriate antiviral management of transplant recipients. Quantitative PCR technologies have demonstrated accuracy in measuring systemic HCMV loads. A total of 298 consecutive whole-blood specimens submitted to the Clinical Virology Laboratory at Vanderbilt University Medical Center from 15 February to 31 October 1999 were included in the study. In addition to a qualitative colorimetric microtiter plate PCR assay (MTP-PCR) and a semiquantitative pp65 antigenemia assay, each specimen was measured for HCMV loads by a quantitative PCR assay performed on an ABI PRISM 7700 Sequence Detection System (TaqMan). Compared to results of the MTP-PCR, the sensitivity, specificity, positive predictive value, and negative predictive value were 70.5, 97.5, 87.8, and 92.8% for the antigenemia assay and were 96.7, 92.0, 75.6, and 99.1% for the TaqMan assay, respectively. There was a high correlation between antigenemia values and HCMV loads as determined by the TaqMan (r = 0.989; P < 0.001). Antigenemia values of 0, 1 to 10, 11 to 100, 101 to 1,000, and over 1,000 positive cells per 2 x 10(5) leukocytes corresponded to median HCMV loads measured by TaqMan of 125, 1,593, 5,713, 16,825, and 5,425,000 copies/ml, respectively. Corresponding to antigenemia values of 1 to 2, 10, and 50 positive cells per 2 x 10(5) leukocytes, HCMV viral loads of 1,000, 4,000, and 10,000 copies/ml are proposed as cutoff points for initiating antiviral therapy in patient groups with high, intermediate, and low risk of CMV diseases.

Cytomegalovirus↗
PubMed2003

Major outbreak of toxic shock-like syndrome caused by Streptococcus mitis.

Severe illness caused by viridans streptococci rarely occurs in immunocompetent hosts. Between December 1990 and May 1991, thousands of patients in the YangZi River Delta area of Jiangsu Province, China, suffered from scarlet fever-like pharyngitis. Fewer cases occurred in subsequent years with the same seasonality. Approximately half of the cases developed complications characteristic of streptococcal toxic shock-like syndrome (TSLS). Throat cultures yielded predominant growth of alpha-hemolytic streptococci. All cases admitted to Haian People's Hospital were investigated. Clinical specimens were collected, medical records were reviewed, and bacterial isolates were identified phenotypically and analyzed by 16S rRNA gene sequencing and pulsed-field gel electrophoresis (PFGE). Proteins were purified from culture supernatants by extraction, ammonium sulfate precipitation, and fast-protein liquid chromatography. Biological activities of protein components were determined by subcutaneous inoculation into rabbits. A total of 178 cases of non-beta-hemolytic streptococcal scarlet fever-like pharyngitis were studied. In 88 (79.3%) of 111 patients, oropharyngeal swab cultures grew morphologically identical alpha-hemolytic streptococci. A protein in culture supernatants was pyrogenic in rabbits, was mitogenic for splenocytes, and enhanced rabbit susceptibility to endotoxin challenge. The N-terminal amino acid sequence of this 34-kDa protein showed no homology with known Streptococcus pyrogenic exotoxins. The organism was identified as Streptococcus mitis based on biochemical and 16S rRNA sequence analyses. Representative outbreak isolates from 1990 to 1995 displayed identical PFGE patterns. This TSLS outbreak in southeastern China was caused by a toxigenic clone of S. mitis. An apparently novel toxin may explain the unusual virulence of this organism.

Animals↗
PubMed2002

Rapidly increasing prevalence of penicillin-resistant Streptococcus pneumoniae in middle Tennessee: a 10-year clinical and molecular analysis.

The clinical and molecular epidemiology of penicillin-resistant Streptococcus pneumoniae and the diagnostic accuracy of a six-primer PCR assay in identifying penicillin resistance were analyzed by using clinical isolates recovered over a 10-year period in middle Tennessee. The prevalence of non-penicillin-susceptible S. pneumoniae isolates (MIC, > or =0.1 microg/ml) increased from 10% in 1990 to 70% in 1999 (P < 0.001). Among S. pneumoniae isolates for which the penicillin MIC was > or =2 microg/ml (highly penicillin-resistant S. pneumoniae [PRSP]), 23 and 5% were resistant to at least three and at least five other antimicrobial classes, respectively. Pulsed-field gel electrophoresis identified 13 unique strain types, with type B accounting for 33% of PRSP isolates. The sensitivity, specificity, and negative and positive predictive values of the PCR assay in detecting PRSP were 99, 100, 99, and 100%, respectively. Penicillin resistance is rapidly increasing among S. pneumoniae isolates in Tennessee. The simultaneous detection of S. pneumoniae and high-level penicillin resistance can be accurately performed with the six-primer PCR assay.

Adolescent↗
PubMed2002

Enterococcus faecium-related outbreak with molecular evidence of transmission from pigs to humans.

Between 24 July and 31 August 1998, thousands of domestic pigs died of hemorrhagic shock in three adjunct counties along the YangZi River in Jiangshu Province, China. From 28 July to 6 September 1998, 40 local farmers (36 males and 4 females, ages 23 to 78 years) were hospitalized with severe illness characterized by high fever, erythematous rash or petechiae, and profound lethargy after contact with sick pigs. Twelve (30%) of these patients died of respiratory failure and shock. Eleven bacterial isolates recovered from 11 blood and cerebrospinal fluid specimens collected from seven patients and two pigs were identified as Enterococcus faecium based on biochemical reactions and 16S rRNA gene sequence analysis. Both pig and human E. faecium isolates displayed indistinguishable antibiotic susceptibility and pulsed-field gel electrophoresis patterns. These data strongly suggest the spread of an outbreak of E. faecium-related sepsis from pigs to humans.

Adult↗
PubMed2002

Bedside diagnosis of influenzavirus infections in hospitalized children.

OBJECTIVE: For preventing nosocomial influenza infections and to facilitate prompt antiviral therapy, an accessible, rapid diagnostic method for influenzavirus is needed. We evaluated the performance of a lateral-flow immunoassay (QuickVue Influenza Test) completed at the bedside of hospitalized children during the influenza season. METHODS: All children who were evaluated at a large teaching hospital during the 1999 to 2000 influenza season were eligible if they were 1) younger than 19 years and hospitalized with respiratory symptoms or 2) younger than 3 years and hospitalized with fever. Each study child had 2 nasal swabs obtained--1 for influenzavirus culture and polymerase chain reaction (PCR) and the other for the QuickVue Influenza Test. The performance of the rapid diagnostic test was compared with the results of culture or PCR for influenza A or B. RESULTS: Of 303 eligible children, 233 (77%) were enrolled. In this population, 19 children had culture- and/or PCR-confirmed influenza A infection, prevalence of 8%. The QuickVue Influenza Test had a sensitivity of 74%, specificity of 98%, positive predictive value of 74%, and negative predictive value of 98%. CONCLUSIONS: Among children hospitalized with fever/respiratory symptoms during the influenza season, negative bedside QuickVue Influenza Tests indicated very low likelihood of influenza infection, whereas positive tests greatly increased the probability of influenza-associated illness.

Adolescent↗