Viral and Bacterial Etiology of Acute Diarrhea among Children under 5 Years of Age in Wuhan, China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Acute diarrhea remains the serious problem in developing countries, especially among children under 5 years of age. Currently, only two or three common diarrhea pathogens were screened at most hospitals in China. The aim of this study was to provide a wide variety of diarrhea pathogens and their antimicrobial resistance patterns in children under 5 years of age.</p><p><b>METHODS</b>Totally 381 stool samples collected from Tongji Hospital between July 1, 2014 and June 30, 2015 were tested by culture and/or polymerase chain reaction for eight kinds of bacteria and five kinds of viruses. An antimicrobial sensitivity test was performed using dilution method recommended by the Clinical and Laboratory Standards Institute.</p><p><b>RESULTS</b>Viral infections were mainly identified in infants (0-11 months), whereas bacterial infections were more prevalent in the age of 24-59 months. About 69.8% of samples were positive for at least one pathogen, 51.7% of samples were virus positive, followed by bacteria positive cases (19.4%), and 12.6% of cases displayed co-infections with two viruses or a virus and a bacterium. Rotavirus was the most prevalent pathogen, followed closely by norovirus, while Salmonella was the most commonly isolated bacteria, followed by diarrheagenic Escherichia coli (DEC) and Campylobacter. More than 40% of Salmonella spp. and DEC isolates were resistant to first-line antibiotics (ampicillin, trimethoprim-sulfamethoxazole, and tetracycline). Around 10% of Salmonella spp. isolates were resistant to ceftriaxone and ciprofloxacin simultaneously. Campylobacter spp. displayed high resistance to ciprofloxacin but kept low resistance to azithromycin and doxycycline.</p><p><b>CONCLUSIONS</b>The etiology of acute diarrhea varies in children of different age groups. The high frequency of infection with viruses suggests the urgent demand for new viral vaccine development. Proper use of antibiotics in the treatment of acute diarrhea is crucial due to the high level of antibiotic resistance.</p>

Epidemiological study of Streptococcus pneumoniae in the nasopharynx of healthy children under 5 years of age in Wuhan / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the population biology of Streptococcus (S.) pneumoniae carried by healthy children under 5 years of age in Wuhan.</p><p><b>METHODS</b>S. pneumoniae was isolated from nasopharyngeal swabs of healthy children under the age of 5 years (under 5) in Wuhan. The susceptibility to 12 antimicrobial agents was tested by agar dilution method. The erythromycin resistant genes were detected by using the technique of polymerase chain reaction. The quellung reaction was used for serotyping.</p><p><b>RESULTS</b>The carrier rate of S. pneumoniae was 22.31% (135/605) in under 5 children in Wuhan. Among the 133 alive strains, the proportion of penicillin non-susceptible S. pneumoniae (PNSSP) was 45.9% (61/133). The susceptibility of S. pneumoniae to the first (cefalexin), the second (cefaclor) and the third (cefixime, cefpodoxime and cetriaxone) generations of cephalosporins was 6.0%, 45.1%, 54.9%, 56.4%, and 88.7%, respectively. None of the strains were found resistant to fluoroquinolones except for one strain which was resistant to ciprofloxacin at low level. The susceptibility to macrolides was low, 14.3% - 15.8%. Among totally 114 strains resistant to erythromycin, the genes ermB alone, both ermB and mefA, and mefA alone were found in 76 strains (66.7%), 46 strains (40.4%) and 2 strains (1.8%), respectively. Seventeen serotypes were involved and the prevalent serotypes were 19, 23, 6, 15 and 14. Seven strains remained nontypable for serotype. PNSSP strains were found to be distributed in serotypes 19, 23, 6 and nontypable group.</p><p><b>CONCLUSIONS</b>The antibiotic resistance of S. pneumoniae was serious in Wuhan area. The ribosomal modification (ermB gene mediated) was the main mechanism of S. pneumoniae resistant to erythromycin. The major prevalent serotypes were 19, 23 and 6.</p>

Genotypes of Plasmid-mediated AmpC Beta-lactamases in Klebsiella pneumoniae / 中华医院感染学杂志

OBJECTIVE To investigate the genotypes of plasmid-mediated AmpC beta-lactamases carried in Klebsiella pneumoniae,to provide reasonable use of antibacterial agents and to reduce the spread of these drug resistant genes.METHODS Two hundred and eighteen strains of K.pneumoniae were performed in Tongji Hospital in Wuhan.Plasmid-mediated AmpC beta-lactamases-producing strains were screened by improved three-dimensional method and identified by multiplex PCR.DNA sequencing method was used to confirm these drug resistant strains.The MIC of 15 kinds of antibacterial agents against the clinical isolates was detected by double agar dilution method.RESULTS Thirteen strains of K.pneumoniae were detected by improved three-dimensional method.The detection rates were 5.96%.There were seven of thirteen positive strains of K.pneumoniae through improved three-dimensional method harboring DHA-1 type plasmid-mediated AmpC beta-lactamase by multiplex PCR and confirmed by DNA sequencing.Plasmid-mediated AmpC beta-lactamase producers revealed a highly drug resistance to cephalosporins,monobactams,beta-lactam/beta-lactamase inhibitor combinations,aminoglycosides and fluoroquinolones.Only imipenem was susceptible to all of these detected strains.CONCLUSIONS DHA-1 plasmid-mediated AmpC beta-lactamase is detected in K.pneumoniae strains from Tongji Hospital.The detection rate is 3.2%.The pAmpC-producing strains reveal multi-drug resistance.Only imipenem is susceptible to them.

Analysis of the distribution characteristics and drug sensitivity of infection pathogens in hematology department ward / 中国实验血液学杂志

The objective of this study was to investigate clinical distribution characteristics and drug sensitivity of infection pathogens in hematology department wards of our hospital during recent two years. The isolation and cultivation of pathogens from samples were performed by routine methods. Drug sensitivity tests of bacteria were performed by Kirby-Bauer method. Drug sensitivity tests of fungi were performed by ATBFUNGUS Drug sensitivity strips. The results showed that 102 strains of pathogens were isolated from all detected samples. The composition ratio of Gram-positive bacteria, Gram-negative bacteria and fungi was 42.2%, 34.3%, 3.5%, respectively. 58.8% of pathogens were isolated from samples of malignant hematopathy patients. 27.5% were isolated from samples of the patients with fever of unknown origin (FUO). 51.0% of pathogens were isolated from samples of the patients who suffered from agranulocytosis or leucocytopenia. Isolated fungi were mostly sensitive to anti-fungal drugs. G+ bacteria were most sensitive to vancomycin. G- bacteria were most sensitive to imipenem. Most bacteria were resistant to multiple antibiotics. It is concluded that the infection in hematology department wards was related with many conditions, such as weakened resistance of patients, leucocytopenia or agranulocytosis, tumor loading, etc. The prompt microbiological examination and drug sensitivity tests are important to rationally select antibiotics, reduce infection incidence and mortality rate, and decrease the occurrence of drug resistant strains.

Studies on drug resistance genes among 49 strains of extended-spectrum beta-lactamase-producing bacteria / 中华检验医学杂志

Objective To investigate the drug resistance genes of extended-spectrum beta- lactamase-producing bacteria in 49 strains.Methods Extended-spectrum ?-lactamase -producing strains were detected by the disc diffusion test.The techniques of polymerase chain reaction,sequence analysis, pulsed-field gel electrophoresis were used to analyze the genotype and homology of extended-spectrum ?- lactamase-producing strains.Results The incidence of ESBL-producing strains from E.coli,K pneumoniae,K oxytoca,was 20% in 2000,and 40% in 2003.Among the 49 ESBLs producers the most common genotype was CTX-M-14( n=33).The others were CTX-M-3,CTX-M-9,CTX-M-12,CTX-M-15, CTX-M-24 and SHVSa.Both two CTX-M subtypes,CTX-M-3 and CTX-M-14,were detected in one strain. However,4 ESBL-producing strains confirmed by phenotype remained untyped.The results showed that the ESBLs producers were not closely related,except for two strains of E.coli and two strains of K.pneumoniae which were homgenic respectively.Concolusions The incidence of ESBL-producing strains increases with years.The most common genotype of ESBLs is CTX-M.There is no evidence for epidemiologic spread of ESBL-producers by pulsed-field gel electrophoresis.