Plasmid-borne colistin resistance gene mcr-1 in a multidrug resistant Salmonella enterica serovar Typhimurium isolate from an infant with acute diarrhea in China.

BACKGROUND: Antimicrobial resistance of Salmonella enterica is a major global concern. Recent findings suggest that colistin as a last resort treatment for multidrug-resistant gram-negative bacteria is seriously threatened by the report of plasmid-mediated colistin resistance gene mcr-1 in China. METHODS: A total of 827 S. Typhimurium isolates were recovered from 4 cities of China, including Henan, Shanghai, Zhejiang, and Hubei provinces. Subsequently, mcr-1 presence was identified by PCR screening. Antimicrobial susceptibility testing was performed by broth microdilution using a 96-well microtiter plate. Plasmid conjugation transfer experiments were conducted using Escherichia coli J53 as the recipient. RESULTS: Only one mcr-1 positive strain from the stool sample of an infant with acute diarrhea was isolated. Apart from colistin, the mcr-1-positive isolate showed co-resistance to the third-generation cephalosporins, ampicillin, nalidixic acid, tetracycline, chloramphenicol, sulfisoxazole, gentamicin, and cefotaxime revealing a multidrug-resistant phenotype. This strain harbored mcr-1 on a 227 kb IncHI2 plasmid, termed pJZ26, which could be transferred to E. coli J53. In addition to mcr-1, pJZ26 coharbored other resistance genes, including aph(4)-Ia, aac(3)-IVa, fosA, floR, sul2, and blaCTX-M-14. Compared with p2474-MCR1 and pHYEC7-IncHI2, pJZ26 contains an additional 4.6 kb fragment harboring the resistance gene tet(A) and its regulator tetR located on TnAs1 transposable element, which could mediate resistance to tetracycline. CONCLUSIONS: These findings highlight that the fact the mcr-1-harboring plasmid pJZ26 has a high potential to disseminate the mcr-1 gene and further challenge the clinical treatment.

Invasive Streptococcus pneumoniae infection among hospitalized patients in Jingzhou city, China, 2010-2012.

BACKGROUND: Streptococcus pneumoniae (Sp) is a leading cause of bacterial pneumonia, meningitis, and sepsis and a major source of morbidity and mortality worldwide. Invasive pneumococcal disease (IPD) is defined as isolation of Sp from a normally sterile site, including blood or cerebrospinal fluid. The aim of this study is to describe outcomes as well as clinical and epidemiological characteristics of hospitalized IPD case patients in central China. METHODS: We conducted surveillance for IPD among children and adults from April 5, 2010 to September 30, 2012, in four major hospitals in Jingzhou City, Hubei Province. We collected demographic, clinical, and outcome data for all enrolled hospitalized patients with severe acute respiratory infection (SARI) or meningitis, and collected blood, urine, and cerebrospinal fluid (CSF) for laboratory testing for Sp infections. Collected data were entered into Epidata software and imported into SPSS for analysis. RESULTS: We enrolled 22,375 patients, including 22,202 (99%) with SARI and 173 (1%) with meningitis. One hundred and eighteen (118, 3%) with either SARI or meningitis were Sp positive, 32 (0.8%) from blood/CSF culture, and 87 (5%) from urine antigen testing. Of those 118 patients, 57% were aged ≥65 years and nearly 100% received antibiotics during hospitalization. None were previously vaccinated with 7-valent pneumococcal conjugate vaccine (PCV 7), 23-valent pneumococcal polysaccharide vaccine, or seasonal influenza vaccine. The main serotypes identified were 14, 12, 3, 1, 19F, 4, 5, 9V, 15 and 18C, corresponding to serotype coverage rates of 42%, 63%, and 77% for PCV7, PCV10, and PCV13, respectively. CONCLUSIONS: Further work is needed to expand access to pneumococcal vaccination in China, both among children and potentially among the elderly, and inappropriate use of antibiotics is a widespread and serious problem in China.

Clinical characteristics and factors associated with severe acute respiratory infection and influenza among children in Jingzhou, China.

BACKGROUND: Influenza is an important cause of respiratory illness in children, but data are limited on hospitalized children with laboratory-confirmed influenza in China. METHODS: We conducted active surveillance for severe acute respiratory infection (SARI; fever and at least one sign or symptom of acute respiratory illness) among hospitalized pediatric patients in Jingzhou, Hubei Province, from April 2010 to April 2012. Data were collected from enrolled SARI patients on demographics, underlying health conditions, clinical course of illness, and outcomes. Nasal swabs were collected and tested for influenza viruses by reverse transcription polymerase chain reaction. We described the clinical and epidemiological characteristics of children with influenza and analyzed the association between potential risk factors and SARI patients with influenza. RESULTS: During the study period, 15 354 children aged <15 years with signs and symptoms of SARI were enrolled at hospital admission. severe acute respiratory infection patients aged 5-15 years with confirmed influenza (H3N2) infection were more likely than children without influenza to have radiographic diagnosis of pneumonia (11/31, 36% vs 15/105, 14%. P<.05). Only 16% (1116/7145) of enrolled patients had received seasonal trivalent influenza vaccination within 12 months of hospital admission. Non-vaccinated influenza cases were more likely than vaccinated influenza cases to have pneumonia (31/133, 23% vs 37/256, 15%, P<.05). severe acute respiratory infection cases aged 5-15 years diagnosed with influenza were also more likely to have a household member who smoked cigarettes compared with SARI cases without a smoking household member (54/208, 26% vs 158/960, 16%, P<.05). CONCLUSIONS: Influenza A (H3N2) virus infection was an important contributor to pneumonia requiring hospitalization. Our results highlight the importance of surveillance in identifying factors for influenza hospitalization, monitoring adherence to influenza prevention and treatment strategies, and evaluating the disease burden among hospitalized pediatric SARI patients. Influenza vaccination promotion should target children.

Epidemiology, Seasonality and Treatment of Hospitalized Adults and Adolescents with Influenza in Jingzhou, China, 2010-2012.

BACKGROUND: After the 2009 influenza A (H1N1) pandemic, we conducted hospital-based severe acute respiratory infection (SARI) surveillance in one central Chinese city to assess disease burden attributable to influenza among adults and adolescents. METHODS: We defined an adult SARI case as a hospitalized patient aged ≥ 15 years with temperature ≥38.0°C and at least one of the following: cough, sore throat, tachypnea, difficulty breathing, abnormal breath sounds on auscultation, sputum production, hemoptysis, chest pain, or chest radiograph consistent with pneumonia. For each enrolled SARI case-patient, we completed a standardized case report form, and collected a nasopharyngeal swab within 24 hours of admission. Specimens were tested for influenza viruses by real-time reverse transcription polymerase chain reaction (rRT-PCR). We analyzed data from adult SARI cases in four hospitals in Jingzhou, China from April 2010 to April 2012. RESULTS: Of 1,790 adult SARI patients enrolled, 40% were aged ≥ 65 years old. The median duration of hospitalization was 9 days. Nearly all were prescribed antibiotics during their hospitalization, less than 1% were prescribed oseltamivir, and 28% were prescribed corticosteroids. Only 0.1% reported receiving influenza vaccination in the past year. Of 1,704 samples tested, 16% were positive for influenza. Influenza activity in all age groups showed winter-spring and summer peaks. Influenza-positive patients had a longer duration from illness onset to hospitalization and a shorter duration from hospital admission to discharge or death compared to influenza negative SARI patients. CONCLUSIONS: There is substantial burden of influenza-associated SARI hospitalizations in Jingzhou, China, especially among older adults. More effective promotion of annual seasonal influenza vaccination and timely oseltamivir treatment among high risk groups may improve influenza prevention and control in China.

[Estimation of hospitalization rate of laboratory confirmed influenza cases in Jingzhou city, Hubei province, 2010-2012].

OBJECTIVE: To estimate the hospitalization rate of severe acute respiratory infection (SARI) cases attributable to influenza in Jingzhou city, Hubei province from 2010 to 2012. METHODS: SARI surveillance was conducted at four hospitals in Jingzhou city, Hubei province from 2010 to 2012. Inpatients meeting the SARI case definition and with informed consent were enrolled to collect their demographic information, clinical features, treatment, and disease outcomes, with their respiratory tract specimens collected for PCR test of influenza virus. RESULTS: From April, 2010 to September, 2012, 19 679 SARI cases enrolled were residents of Jingzhou, and nasopharyngeal swab was collected from 18 412 (93.6%) cases of them to test influenza virus and 13.3% were positive for influenza. During the three consecutive 2010-2012 flu seasons, laboratory-confirmed influenza was associated with 102 per 100 000, 132 per 100 000 and 244 per 100 000, respectively. As for the hospitalization rate attributable to specific type/subtype of influenza virus, 48 per 100 000, 30 per 100 000 and 24 per 100 000 were attributable to A (H3N2), A (H1N1) pdm2009, and influenza B, respectively in 2010-2011 season; 42 per 100 000 [A (H3N2)] and 90 per 100 000 (influenza B) in 2011-2012 season; 90 per 100 000 [A (H3N2)] and one per 100 000 [influenza B] from April, 2010 to September, 2012. SARI hospitalization caused by influenza A or B occurred both mainly among children younger than five years old, with the peak in children aged 0.5 year old. CONCLUSION: Influenza could cause a substantial number of hospitalizations and different viral type/subtype result in different hospitalizations over influenza seasons in Jingzhou city, Hubei province. Children less than five years old should be prioritized for influenza vaccination in China.

The substantial hospitalization burden of influenza in central China: surveillance for severe, acute respiratory infection, and influenza viruses, 2010-2012.

BACKGROUND: Published data on influenza in severe acute respiratory infection (SARI) patients are limited. We conducted SARI surveillance in central China and estimated hospitalization rates of SARI attributable to influenza by viral type/subtype. METHODS: Surveillance was conducted at four hospitals in Jingzhou, China from 2010 to 2012. We enrolled hospitalized patients who had temperature ≥37·3°C and at least one of: cough, sore throat, tachypnea, difficulty breathing, abnormal breath sounds on auscultation, sputum production, hemoptysis, chest pain, or chest radiograph consistent with pneumonia. A nasopharyngeal swab was collected from each case-patient within 24 hours of admission for influenza testing by real-time reverse transcription PCR. RESULTS: Of 17 172 SARI patients enrolled, 90% were aged <15 years. The median duration of hospitalization was 5 days. Of 16 208 (94%) SARI cases tested, 2057 (13%) had confirmed influenza, including 1427 (69%) aged <5 years. Multiple peaks of influenza occurred during summer, winter, and spring months. Influenza was associated with an estimated 115 and 142 SARI hospitalizations per 100 000 during 2010-2011 and 2011-2012 [including A(H3N2): 55 and 44 SARI hospitalizations per 100 000; pandemic A(H1N1): 33 SARI hospitalizations per 100 000 during 2010-2011; influenza B: 26 and 98 hospitalizations per 100 000], with the highest rate among children aged 6-11 months (3603 and 3805 hospitalizations per 100 000 during 2010-2011 and 2011-2012, respectively). CONCLUSIONS: In central China, influenza A and B caused a substantial number of hospitalizations during multiple periods each year. Our findings strongly suggest that young children should be the highest priority group for annual influenza vaccination in China.

[Application of pulsed-field gel electrophoresis in a food-borne outbreak of Salmonella serotype Muenchen infection].

OBJECTIVE: To investigate the application of pulsed-field gel electrophoresis (PFGE) in food-borne outbreak. METHODS: Pathogens were isolated and further characteristics identified by traditional methods. The strains isolated were carried out with molecular typing with using PFGE. PFGE was performed by Laboratory Directions for molecular subtyping of Salmonella by PFGE (CDC, USA) and the results of PFGE were analyzed by BioNumerics soft. RESULTS: Totally 14 Salmonella serotype Muenchen strains were isolated from 19 patients, 3 of 9 suspicious foods were positive for S. muenchen and 7 strains were isolated from 18 cooks. The biochemistry characterization and antimicrobial susceptibility of all the strains isolated were the same. 23 S. muenchen isolates were all shown indistinguishable by PFGE. CONCLUSION: PFGE should play a key role in identifying the outbreak-associated isolates and distinguishing them from unrelated sporadic isolates. It might also demonstrate that the genetic fingerprints of serotype Muenchen isolates derived from patients were indistinguishable from those derived from drinks. PFGE might provide precise information on bacterial food-borne pathogens, promptly identify the source of infection, and effectively prevent from spreading. It should be one of the early warning method on controlling outbreak of the food-borne disease.