Penetration of erythromycin through Staphylococcus epidermidis biofilm / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The catheter related infection caused by Staphylococcus epidermidis biofilm is increasing and difficult to treat by antimicrobial chemotherapy. The properties of biofilms that give rise to antibiotic resistance are only partially understood. This study aimed to elucidate the penetration of erythromycin through Staphylococcus epidermidis biofilm.</p><p><b>METHODS</b>The penetration ratio of erythromycin through Staphylococcus epidermidis biofilms of 1457, 1457-msrA, and wild isolate S68 was detected by biofilm penetration model at different time points according to the standard regression curve. The RNA/DNA ratio and the cell density within the biofilms were observed by confocal laser microscope and transmission electromicroscope, respectively.</p><p><b>RESULTS</b>The penetration ratios of erythromycin through the biofilms of 1457, 1457-msrA, and S68 after cultivation for 36 hours were 0.93, 0.55 and 0.4, respectively. The erythromycin penetration ratio through 1457 biofilm (0.58 after 8 hours) was higher than that through the other two (0.499 and 0.31 after 24 hours). Lower growth rate of the cells in biofilm was shown, with reduction of RNA/DNA proportion observed by confocal laser microscope through acridine orange stain. Compared with the control group observed by transmission electrmicroscope, the cell density of biofilm air face was lower than that of agar face, with more cell debris.</p><p><b>CONCLUSIONS</b>Erythromycin could penetrate to the Staphylococcus epidermidis biofilm, but could not kill the cells thoroughly. The lower growth rate of the cells within biofilm could help decreasing the erythromycin susceptibility.</p>

Study on the molecular epidemiological characteristics of norovirus in acute gastroenteritis of Beijing / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the prevalence, genotypes and molecular characteristics of norovirus (NoV) in acute gastroenteritis.</p><p><b>METHODS</b>RT-PCR was used to determine the molecular epidemiology of NoV.</p><p><b>RESULTS</b>Out of 685 samples, 66 positive specimens were identified and the prevalence was 9.6% (66/685), 9.9% in males and 9.4% in females, respectively, with no significant difference. The prevalence rates showed no differences between age groups or between inpatients and outpatients. NoV gastroenteritis did not present any seasonal distribution. 43 out of the 66 specimens were classified, with 10 (22.7%) belonged to GI including 2 GI.3, 1 GI.4, 4 GI.5 and 3 GI.7. Other 33 (77.3%) belonged to GII genogroup, including GII.4 accounted for 60.6% (20/33) and followed by 7 GII.12, 2 GII.6, 1 GII.2, 1 GII.3, 1 GII.5. Six specimens mixed with GI and GII and 3 specimens were classified as GI.3/GII.7, GI.5/GII.5 and GI.4/GII.4.</p><p><b>CONCLUSION</b>The main symptoms of acute gastroenteritis were abdominal pain, nausea, vomit and fever. There were many genotypes identified in our study and the main genotypes were GII.4/2006a and 2006b. GI and GII could be coinfected with each other.</p>

Viral shedding in Chinese young adults with mild 2009 H1N1 influenza / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The duration of viral shedding and the transmission of 2009 H1N1 influenza among individuals, especially among the younger population with mild illness, are not well understood now. The aim of this study was to determine the viral shedding of the young adult patients with mild 2009 H1N1 influenza in China.</p><p><b>METHODS</b>From September 2009 to January 2010, the clinical data and serial nasopharyngeal swabs of 67 patients with 2009 H1N1 influenza and 37 patients with seasonal influenza aged from 18 years to 35 years were collected. The nasopharyngeal swab samples were detected by real time RT-PCR to determine the viral shedding. All the patients did not receive the antiviral therapy but Chinese medicine for detoxicating.</p><p><b>RESULTS</b>Among the patients with H1N1 virus infection, 82.1% (55/67) patients presented with fever symptom, while more patients with high fever (≥ 39°C) were found in seasonal influenza patients (P < 0.05). For the H1N1 patients, the median interval between the symptom onset and the undetectable RNA was six days (4 - 10 days). But viral shedding was still found in 31.3% patients after 7 days following illness onset. The median interval between disappearance of fever and an undetectable viral RNA level was three days (2 - 8 days), and 17.9% patients were found to be viral shedding 6 days later after normalization of body temperature. For the seasonal influenza patients, 94.6% patients were detected out viral RNA within 7 days. The median interval of seasonal influenza between the symptom onset and the undetectable RNA was four days (3 - 8 days). The median interval between disappearance of fever and an undetectable viral RNA level was three days (2 - 6 days).</p><p><b>CONCLUSION</b>It suggests that 7 days isolation period from the illness onset or 24 hours after the resolution of fever and respiratory symptoms are not long enough to cut off the transmission among Chinese young adults with mild illness.</p>

Colloidal gold and dot-ELISA rapid tests for screening influenza A virus / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the diagnostic efficiency of colloidal gold and dot ELISA rapid tests in clinical screening of influenza A virus.</p><p><b>METHODS</b>The pharyngeal swabs were collected from 297 outpatients suspected of influenza between June and October, 2009 for detection with colloid gold and dot ELISA rapid test, with real-time PCR as the golden methods. The discrepant results of colloid gold and dot ELISA methods were confirmed by sequencing, and the diagnostic efficiency of the two methods was evaluated.</p><p><b>RESULTS</b>Among the 166 samples with influenza A virus infection as confirmed by real-time PCR and sequencing, the diagnostic sensitivity of dot ELISA and colloid gold methods was 54.82% (91/166) and 4.22% (7/166), respectively. The total concordance rate with PCR was 66.67% (Kappa value of 0.35). Among the 133 samples negative for influenza A virus, the specificity of dot ELISA and colloid gold methods was 81.68% (107/131) and 98.47% (129/131), respectively, with a total concordance rate with PCR of 45.79% (Kappa value 0.02). Of the 99 H1N1 influenza samples confirmed by real-time PCR, the detection rate of dot ELISA was 67.3%, whereas that of colloid gold was 5.1%. Out of the 107 dot ELISA-positive but colloid gold-negative samples, 84 were confirmed to be influenza A virus-positive by real-time PCR and sequencing. One sample negative for dot ELISA but positive for colloid gold test was confirmed to be influenza A virus-negative. The detection rate and diagnostic concordance rate for influenza A virus by dot ELISA were significantly higher than those of colloid gold (P<0.05).</p><p><b>CONCLUSION</b>Dot ELISA is better than colloid gold in influenza A virus detection and shows great prospect in clinical screening.</p>

Clinical manifestations and epidemic factors of autumn-winter type scrub typhus in children from northern new endemic area / 中华儿科杂志

<p><b>OBJECTIVE</b>Scrub typhus is an infectious disease due to Orientia tsutsugamushi transmitted by infected chigger mites. Scrub typhus has long been recognized to occur in southern areas of China, but has recently been increasingly often reported from the north since the first case was reported in Mengyin County, Shandong Province in 1986. The key objectives of the present study were to investigate the clinical manifestations and epidemic factors of scrub typhus in children from the northern new natural foci.</p><p><b>METHODS</b>The case records of 56 children with scrub typhus who were admitted to the 5 hospitals of Fei County from September 1993 to January 2004 were reviewed. Orientia tsutsugamushi (Ot) was isolated from the cases. Based on ecological observations on the composition, seasonal fluctuation of animal hosts and chigger mites, Ot was isolated from rodents and chiggers. IgG antibodies to Ot was detected by IFA. Genotypes of the Ot isolates were also identified by nested PCR.</p><p><b>RESULTS</b>Among 56 children scrub typhus cases, 46 were male, 10 were female; 96% exhibited typical eschars or ulcers, 100% cases had high fever, skin rashes were observed in 55 cases (98%), and regional lymphadenopathy occurred in 48 cases (86%). All cases came from countryside, and all had histories of exposure to the crop field. fifty-one serum samples of suspected patients with scrub typhus were collected, 48 were positive for antibodies to Ot. The serotypes were Gilliam types. The cases only appeared in September to December with the peak at mid and late October. Leptotrombidium (L.) scutellare was the most important vector causing scrub typhus in the foci. Apodemus (A.) agrarius was the main host animals of Ot in the crop field. Totally 26 strains were isolated from patients, rodents, and chigger mites. The serotypes of 24 out of the 26 isolates were Gilliam types, while the genotypes of these isolates were Kawasaki types. The serotypes of the other 2 isolates were identical and both were Karp types.</p><p><b>CONCLUSION</b>Children scrub typhus patients were frequently seen in the new natural foci of Shandong province. Exposure history, typical eschars or ulcers, and presence of IgG antibody were the important indexes to diagnose the disease.</p>

Amplification and restriction fragment length polymorphism analysis on the complete sequence of Sta56 gene of Orientia tsutsugamushi isolated from Shandong area / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the genetic differences of Orientia tsutsugamushi (Ot) Sta56 gene between Shandong isolates and other strains deposited in GenBank.</p><p><b>METHODS</b>PCR and restriction fragment length polymorphism (RFLP) were used to amplify the complete sequence of Ot-Sta56 gene. RFLP profiles of Ot were predicted by a computer program according to their complete sequences of Ot-Sta56 gene. PCR amplicon from XDM2 strain was sequenced and analyzed by Clustal X (1.8) and PHYLIP software.</p><p><b>RESULTS</b>The complete sequences (about 1.6 kbp) of Ot-Sta56 gene were amplified from B16 strain (isolated from patients), FXS2 strain (isolated from A. agrarius) and XDM2 strain. Four species of restriction endonucleases (Hha I, Hinf I, Hae III, Pst I) were used to digest the PCR amplicons from the 3 isolates. When comparing with the RFLP profiles of prototype Ot, the RFLP profiles of PCR amplicons from the 3 isolates were similar to those of Japan Kawasaki strain, but were quite different from the international reference strains Gilliam, Karp, Kato. Results from DNA sequence analysis showed that the complete sequence of Ot-Sta56 gene homology to Japan Kawasaki strain of XDM2 strain was 97%, and deduced amino acid sequence was 92%.</p><p><b>CONCLUSION</b>Data from the complete sequence of Sta56 gene indicated that the genotypes of Ot isolates in Shandong province were similar, but with distinction from the Kawasaki strain.</p>

Nucleotide sequence characterization and phylogenetic analysis of hantaviruses isolated in Shandong Province, China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>China is the most severe endemic area of hemorrhagic fever with renal syndrome (HFRS) in the world with 30,000-50,000 cases reported annually, which accounts for more than 90% of total number of cases worldwide. The incidence rate of the syndrome in Shandong Province is one of the highest in China, which has ever reached 50 per 100,000 persons per year. However, the molecular characteristics of hantaviruses (HV) epidemic in Shandong Province remain unclear. Therefore it is useful to clarify nucleotide sequence and phylogenetic characteristics of HV isolated in Shandong Province in order to provide better advices to control and prevent HFRS.</p><p><b>METHODS</b>RNAs were extracted from sera of clinically diagnosed patients and positive rodent lungs that were detected by indirect immunofluorescent assay (IFA). Partial M segments of HV were amplified from the RNAs with reverse transcription nested polymerase chain reactions (nested PCR) using hantavirus genotype specific primers. The nested PCR products were sequenced and compared with those from previously epidemic isolates in Shandong and with other representative HV sequences from GenBank. Phylogenetic tree analyses were performed based on the sequences of the M genes.</p><p><b>RESULTS</b>Thirty-four HV isolates in Shandong showed 67.1%-100% nucleotide identities. The nucleotide homologies among 6 Hantaan viruses (HTNV) isolates in Shandong were 78.1%-98.7%, while the homologies among 28 Seoul virus (SEOV) isolates in Shandong were 93.7%-100%. There were at least 3 subtypes HTNV (H2, H5, H9) and 2 subtypes SEOV (S2, S3) in Shandong Province.</p><p><b>CONCLUSIONS</b>In Shandong Province, the homologies of HTNV were lower and there were no predominant subtypes, while the homologies of SEOV were higher and S3 was the predominant subtype. The homologies of SEOV from rodents were higher than those from patients. The distribution of subtypes in Shandong was similar to that of the adjoining provinces. Phylogenetic analyses of the sequences showed geographic clustering of HV in Shandong.</p>

Genotype identification and sequence analysis of Orientia tsutsugamushi isolated from Shandong area / 中华流行病学杂志

<p><b>OBJECTIVE</b>To determine genotype, nucleotide sequence homology and phylogenesis of Orientia tsutsugamushi isolated from Shandong, China.</p><p><b>METHODS</b>Orientia tsutsugamushi isolated from patients, Apodemus agrarius and Leptotrombidium scutellare in Shandong area were identified by nested-PCR. On the basis of the nucleotide sequence of the gene that encoding the Ot M, 56 x 10(3) antigen, the primers were frequently used in Japan and Korea. Nucleotide sequences of three isolates were determined. The DNA sequences were compared with nucleotide sequences of Orientia tsutsugamushi registered in GenBank for sequence homology analysis. Phylogenetic analysis of the isolates and'some published sequences was carried out with Neighbor-joining method by MEGA 3.1 software.</p><p><b>RESULTS</b>481- 507 bp DNA fragments encoding Orientia tsutsugamushi M, 56 x 10(3) protein were amplified successfully in the samples of Gilliam, Karp, Kato and Shandong isolates by group-specific primers. The corresponding target fragments of the three international reference strains of Gilliam, Karp, and Kato were amplified successfully with each of their own type specific primers. 523 bp DNA fragments were amplified successfully from Shandong isolates by the nPCR with Kawasaki-specific primer, and no DNA fragment was amplified by the nPCR with Gilliam, Karp, Kato, Kuroki and Saitama-specific primer. Comparing with the sequences of Orientia tsutsugamushi registered in GenBank, all the Shandong isolates shared higher than 95% nucleotide sequence homology with Kawasaki strain founded in Japan. Data from phylogenetic analysis showed that Shandong isolates belonged to the same branch with Kawasaki strain.</p><p><b>CONCLUSION</b>To facilitate international comparison and communication, the primers should be employed in the Orientia tsutsugamushi research in China. Orientia tsutsugamushi isolated in China were similar to Kawasaki strain</p>

Investigation on rodents' natural infection of Orientia tsutsugamushi in some areas of Inner Mongolia and Xinjiang, China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate rodents' natural infection of Orientia tsutsugamushi (Ot) in some areas of Inner Mongolia and Xinjiang, China.</p><p><b>METHODS</b>DNAs were extracted from spleens of the captured mice and nested-polymerase chain reaction (nPCR) technique was used to detect the Ot-Sta56 gene. Six positive samples were sequenced and analyzed by Clustal X (5.0) and DNA Club software.</p><p><b>RESULTS</b>A total of 90 rodents were captured in Inner Mongolia, and the overall prevalence of Ot was 6.67%. There was no significant difference in infection rates among the positive rodents species. 20 rodents were captured in Xinjiang, and the prevalence of Ot was 5.00%. The geographical difference in infection rates was not statistically significant between Inner Mongolia and Xinjiang. 9 rodents were captured in farmlands of Inner Mongolia and Xinjiang but there was no positive samples found. 101 rodents were captured in grasslands, and the prevalence of Ot was 6.93%. The Sta56 gene nucleotide sequence homology to Karp strain of N59 (from Microtus maximowiczii), N69 (from Cricetulus barabensis) and X33(from Cricetus cricetus) was 99%. The sequence homology to Taitung-2 strain and TW461 strain of N65 (from C. barabensis) was 94%, and the sequence homology to Taitung-2 strain and TW461 strain of N88(from Apodemus agrarius) was also 94%. The sequence homology to Oishi strain of N90 (from A. agrarius) was 96.00%.</p><p><b>CONCLUSION</b>Our findings indicated that infections of Ot did exist in rodents captured from Inner Mongolia and Xinjiang. The genotypes of Ot in Inner Mongolia and Xinjiang were quite complex, with some of them belonged to Karp type, and the others belonged to Taitung-2, TW461 and Oishi types which providing evidence for further investigation on the scrub typhus fuci in the two areas.</p>

Amplification and typing of Sta56 gene of Orientia tsutsugamushi from Shandong province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To clarify the gene type of Orientia tsutsugamushi (Ot) from Shandong province.</p><p><b>METHODS</b>Nested-polymerase chain reaction (nPCR) was used to identify the gene type of 23 isolated Ot strains, 2 pools of homogenized leptotrombidium (L.) scutellare, 10 blood specimens of scrub typhus patients, and at the same time to compare with the international reference strains Gilliam, Karp, Kato. Sequencing analysis of the Sta56 gene was also used to further identify the precise gene types.</p><p><b>RESULTS</b>Of the 35 samples, 33 had the same products in the amplification of template Ot-DNA. They all belonged to Kawasaki strains endemic in Japan while 2 (FXS4 and LHGM2 strain) belonged to Karp strains. The Sta56 gene sequence homologies to Japan Kawasaki strain of the 2 representative strains (B-16 and FXS2 strain) of the 33 samples were 94.22%, 95.21% respectively, but they were less than 75.87% to other prototype strains; The homologies to Karp strain of FXS4 and LHGM2 strain were 83.03%, 96.45% respectively. B-16 and FXS2 strain were designated as of types strain Japan Kawasaki, FXS4 and LHGM2 as Karp strain.</p><p><b>CONCLUSION</b>The results indicated that the dominant Ot strains in Shandong Province were similar to Kawasaki strains, but Karp strains also existed.</p>