Antimicrobial resistance and prevalence of CvfB, SEK and SEQ genes among Staphylococcus aureus isolates from paediatric patients with bloodstream infections

Staphylococcus aureus (S. aureus) is one of the most frequently isolated pathogens in neonatal cases of early and late-onset sepsis. Drug resistance profiles and carriage of toxin genes may affect the treatment and outcome of an infection. The present study aimed to determine the antimicrobial resistance patterns and frequencies of the toxin-associated genes conserved virulence factor B (CvfB), staphylococcal enterotoxin Q (SEQ) and staphylococcal enterotoxin K (SEK) among S. aureus isolates recovered from paediatric patients with bloodstream infections (BSIs) in Guangzhou (China). Of the 53 isolates, 43.4% were methicillin-resistant S. aureus (MRSA), and resistance rates to penicillin, erythromycin, clindamycin, trimethoprim/sulfamethoxazole, tetracycline, and ciprofloxacin of 92.5, 66.0, 62.3, 13.2, 20.8 and 1.9% were recorded, respectively. However, no resistance to nitrofurantoin, dalfopristin/quinupristin, rifampicin, gentamicin, linezolid or vancomycin was detected. Resistance to erythromycin, clindamycin and tetracycline in the MRSA group was significantly higher than that in the methicillin-susceptible S. aureus (MSSA) group. No significant differences in antimicrobial resistance patterns were noted between two age groups (≤1 year and >1 year). The proportion of S. aureus isolates positive for CvfB, SEQ and SEK was 100, 34.0 and 35.8%, respectively, with 24.5% (13/53) of strains carrying all three genes. Compared with those in MSSA isolates, the rates of SEK, SEQ and SEK + SEQ carriage among MRSA isolates were significantly higher. Correlations were identified between the carriage of SEQ, SEK and SEQ + SEK genes and MRSA (contingency coefficient 0.500, 0.416, 0.546, respectively; P<0.01). In conclusion, MRSA isolated from the blood of paediatric patients with BSIs not only exhibited higher rates of antimicrobial resistance than MSSA from the same source, but also more frequently harboured SEK and SEQ genes. The combination of the two aspects influenced the dissemination of MRSA among children. The present study clarified the characteristics of BSI-associated S. aureus and enhanced the current understanding of the pathogenicity and treatment of MRSA.

[The coping styles and its relationship with quality of life among 1 968 female breast cancer patients in Shanghai in 2014]

Objective: To study the coping styles and its relationship with quality of life among part of the female breast cancer patients in Shanghai in 2014. Methods: In August of 2014, 1-3 block groups affiliated to Shanghai Cancer Rehabilitation Club were selected from each of the 17 districts of Shanghai by convenient sampling method. Respondents were recruited from these block groups via putting up posters in the community or top three hospitals nearby. The inclusion criteria were as follows: female, aged from 18 to 80 years old; the initial diagnosis or primary tumor was breast cancer, and active treatments including surgery, radiotherapy and chemotherapy were finished; capable of basic reading and comprehension, and there was no communication disorder; daily activities were not limited, and with no mental disorder or dysgnosia. Totally 2 205 respondents were included. Questionnaire survey was conducted to collect the information of demographic characteristics, disease characteristics, result of European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), and result of the Ways of Coping Inventory-Cancer Version (WOC-CA). 1 968 valid questionnaires were withdrawn. The results of respondent characteristics and WOC-CA were under descriptive analysis, and the differences of coping styles among groups of different demographic characteristics were compared using t test. In addition, we analyzed the correlation between respondents' coping styles and quality of life using partial correlation analysis. Results: The average age of the 1 968 respondents was (58.7±7.4) years old, and BMI was (24.4±5.4) kg/m(2). The score of positive coping styles was 2.04±0.41, and the score of negative coping styles was 1.79±0.33. The scores of Physical Functioning (PF), Role Functioning (RF), Cognitive Functioning (CF), Emotional Functioning (EF), Social Functioning (SF), and Global Health (GH) were 83.40±12.18, 90.80±15.92, 80.72±16.29, 84.67±15.19, 80.99±20.91, 65.27±21.21, respectively. Positive coping styles correlated with PF, EF, and GH positively, and the correlation coefficients were separately 0.581 (P=0.046), 0.593 (P=0.045), 0.770 (P<0.001). Negative coping styles correlated with RF, CF, EF, and SF negatively, and the correlation coefficients were separately-0.672 (P=0.021),-0.815 (P=0.005),-0.121 (P<0.001),-0.123 (P<0.001). Conclusion: Part of the female breast cancer patients in Shanghai in 2014 mainly adopted positive coping styles, and in general the positive coping styles correlated with quality of life positively and negative coping styles correlated with quality of life negatively.

Pneumococcal serotype distribution and antimicrobial resistance in Chinese children hospitalized for pneumonia

A prospective study was performed to determine serotype distribution and antimicrobial resistance in Streptococcus pneumoniae (S. pneumoniae) from Chinese children <5 years old meeting pneumonia criteria. A total of 3865 children were enrolled and 338 S. pneumoniae isolates were obtained. The most frequent serotypes were 19F (55.6%), 19A (13.9%), 23F (10.1%), 6B (4.7%), and 14 (3.6%). The 7-, 10- and 13-valent conjugate vaccines, respectively, covered 76.3%, 76.9%, and 92.3% of isolates. Out of the isolates, six (1.8%) were penicillin resistant. All except 1 of the isolates were resistant to erythromycin. Serotype 19A showed the highest drug resistance. The use of PCV7 has the potential to prevent a substantial number of pneumococcal infections. However, PCV13 is likely to prevent more episodes of pneumococcal disease in China because of the high rates of 19A.

[Cloning and sequence analysis of UreB of Helicobacter pylori isolated from children]

OBJECTIVE

To clone UreB gene of Helicobacter pylori (H. pylori) isolated from children to pGEX-4T-1 expression plasmid, and do sequence analysis.

METHODS

A pair of specific primer was designed according to H. pylori UreB gene in the GenBank. Using H. pylori strains isolated from children as a template, a UreB gene was obtained by PCR. After EcoR I and Not I digestion, the PCR production was linked with pGEX-4T-1 which was digested with the same enzymes. The recombinant plasmid was transformed into E.coli BL21 and identified by double enzyme digestion and sequence analysis. The sequence results were compared with the gene sequence in the GenBank.

RESULTS

A UreB gene was successfully amplified from children's H. pylori strain GZCH1. It was 1710 bp in size. The objective band was identified by double enzyme digestion. DNA sequence showed that UreB was in the correct open reading frame. The sequence comparison analysis showed that DNA and amino acid sequence identities of UreB gene with other strains were 98%. The sequence of UreB of H. pylori strain GZCH1 was submitted to GenBank (accession number:FJ455126).

CONCLUSIONS

UreB of H. pylori strain GZCH1 is successfully cloned to pGEX-4T-1, which provides a basis for research of oral H. pylori vaccine.

[Antimicrobial resistance and penicillin resistance-associated genes of Streptococcus pneumoniae isolated from children with respiratory tract infection]

OBJECTIVE

To investigate the antimicrobial resistance and penicillin resistance-associated genes (TEM and pbp2B) of Streptococcus pneumoniae (S. pneumoniae) isolated from sputum specimens of Guangzhou children with respiratory tract infection.

METHODS

E-test and Kirby-Bauer methods were applied to detect the antibiotic susceptibility of 44 strains of S. pneumoniae. PCR was used to detect resistance genes pbp2B and TEM, followed by DNA sequence analysis of pbp2B gene. The sequence results were compared to those of penicillin-susceptible S. pneumoniae R6.

RESULTS

Of the 44 isolates of S. pneumoniae, only 5 (11.4%) were susceptible to penicillin. All strains were resistant to erythromycin but susceptible to ofloxacin and vancomycin. The resistance rate of the isolates to clindamycin and trimoxazole was more than 90%. The S. pneumoniae isolates showed a high susceptibility to amoxicillin, imipenem and ceftriaxone, with a resistance rate of 0, 2.6% and 3.9%, respectively. The sequence analysis showed that more than 99% nucleotide sequence of pbp2B gene of five penicillin-susceptible isolates was the same as penicillin-susceptible S. pneumoniae R6, without any amino acid replacement. Site mutation was found in the remaining 39 penicillin-nonsusceptible isolates with a nucleotide mutation rate ranging from 13.2% to 23.1% and amino acid replacement rate from 6.5% to 10.9%. The 39 penicillin-nonsusceptible isolates were classified into 4 types according to the mutation site between Ser391 and Thr492 of pbp2B: type I (n=30), type II (n=7), type III (n=1) and type IV (n=1). No TEM gene was detected in all the 44 S. pneumoniae isolates.

CONCLUSIONS

The S.pneumoniae isolates from Guangzhou children with respiratory tract infection are resistant to penicillin and erythromycin. Amoxicillin and the third generation cephalosporin may be recommended for treating S. pneumoniae infection. The mutation of pbp2B gene plays an important role in the development of S. pneumoniae resistance to penicillin.

[Investigation of campylobacter jejuni infection in children with diarrhea in Guangzhou]

OBJECTIVE

To investigate the incidence of campylobacter jejuni (CJ) infection and the drug resistance of CJ in children with diarrhea in Guangzhou.

METHODS

The fecal samples of 3,351 children with diarrhea between July 2005 and June 2008 were collected for CJ culture. The species of CJ strains were identified by Lior methods. The drug susceptibility tests were performed by the Kirby-Bauer method.

RESULTS

Two hundred and sixty-seven CJ strains (8.0%) were isolated from 3,351 samples. The children at age of 1 month to 1 year were susceptible to CJ, accounting for 91.0%. A higher incidence of CJ infection (76.8%) was found in summer and autumn. The CJ strains were susceptible to imipenem, amikacin, cefoperazone/sulbactam, chloramphenicol, macrolides and lincomycins. Parts of CJ strains (20%-40%) were resistant to ampicillin, quinolones and ambramycin. All CJ strains were resistant to sulfamethoxazole/trimethoprim and cefditoren. Two hundred and one strains (75.3%) were CJ biotype I.

CONCLUSIONS

CJ is an important pathogen of diarrhea in children from Guangzhou. CJ is resistant to some antibiotics used often in clinical practice, and so it is thus important to use antibiotics based on the results of drug susceptibility tests in children with CJ infection.

[Distribution and antibiotic resistance of pathogens isolated from children with infectious diarrhea in Guangzhou]

OBJECTIVE

To study the distribution and antibiotic resistance of the isolated pathogens from children with infectious diarrhea in Guangzhou.

METHODS

The fecal samples of 2 409 children with infectious diarrhea between January 2006 and December 2007 were collected and cultured. Pathogenic bacterium were isolated and identified by biochemical and serological methods. The antibiotic susceptibilities were tested by the Kirby-Bauer method.

RESULTS

A total of 448 isolates of pathogenic bacterium (18.6%) were obtained, including Shigella (n=159), enteropathogenic Escherichia coli (n=141), Salmonella (n=76), Vibrion (n=11), fungus (n=41), and C jejuni (n=20). All of isolates of the three major pathogenic bacterium, Shigella, enteropathogenic Escherichia coli and Salmonella, were susceptible to imipenem and less than 10% of the isolates were resistant to the third generation cephalosporins and beta-lactamase inhibitors. However, the isolates showed a high resistance to ampicillin and sulfamethoxazole/trimethoprim (>75%).

CONCLUSIONS

Shigella, enteropathogenic Escherichia coli and Salmonella were major pathogenic bacterium of diarrhea in children from Guangzhou. The major isolates were susceptible to imipenem, the third generation cephalosporins and beta -lactamase inhibitors, but were resistant to ampicillin and sulfamethoxazole/trimethoprim.

[Surveillance of antibiotic resistance of Streptococcus pneumoniae isolated from hospitalized patients with pneumonia in four children's hospitals in China]

OBJECTIVE

To investigate the antimicrobial resistance of Streptococcus pneumoniae (S.pneumoniae) isolated from Chinese children with pneumonia.

METHODS

Hypopharyngeal aspirate specimens were collected from hospitalized children with pneumonia who were admitted to the children's hospital located in Beijing, Shanghai, Guangzhou or Shanghai from February 16, 2006 to February 16, 2007. The minimum inhibitory concentration (MIC) of S.pneumoniae isolates against penicillin, amoxicillin, cefuroxime (sodium), ceftriaxone, erythromycin, vancomycin, ofloxacin and imipenem was determined by E-test method.

RESULTS

A total of 279 S.pneumoniae isolates were obtained. Eighty-six percent of the isolates were not susceptive to penicillin, and 23.3% was resistant to penicillin. The rate of susceptibility of the isolates to amoxicillin was 92.1%, and to cefuroxime and ceftriaxone was 19.0% and 75.3%, respectively. The isolates also showed a high susceptibility to vancomycin (99.6%) and ofloxacin (97.8%). Seventeen point six percent of the isolates were not susceptive to imipenem, and most of those were intermediate. Almost of all isolates were resistant to erythromycin. There were some distinct regional differences in the susceptibility to antimicrobials tested except for erythromycin, vancomycin and ofloxacin.

CONCLUSIONS

The S.pneumoniae isolates from Chinese children with pneumonia were susceptive to amoxicillin, vancomycin and ofloxacin, but were not susceptive or resistant to penicillin, cefuroxime and erythromycin. The isolates kept susceptibility to ceftriaxone and imipenem to a certain extent.

Usefulness of diffusion/perfusion-weighted MRI in patients with non-enhancing supratentorial brain gliomas: a valuable tool to predict tumour grading?

22 patients with non-enhancing supratentorial gliomas on contrast-enhanced MRI underwent both diffusion- and perfusion-weighted MRI (DWI/PWI) before surgical resection. 14 low-grade gliomas (WHO Grade I and II) and 8 anaplastic gliomas were verified histologically. Both apparent diffusion coefficient (ADC) values and relative cerebral blood volume (rCBV) ratios were calculated on the solid portion of the tumour, on peritumoural area, as well as on the contralateral normal white matter, respectively. The results showed that lower ADC values were present in the solid portions of anaplastic gliomas, but not in low grade (p < 0.01). All ADC values in peritumoural regions of tumours were decreased compared with the contralateral normal white matter. However, there was no significant difference between anaplastic gliomas and low-grade gliomas. Meanwhile, higher rCBV ratios were present in both solid portions and peritumoural regions of anaplastic gliomas, but not in low grade gliomas (p < 0.01). In conclusion, non-enhancing brain gliomas with lower ADC values in the solid portions and higher rCBV ratios in both solid portions and peritumoural regions of tumours are significantly correlated with anaplasia. Therefore, DWI and PWI should be integrated in the diagnostic work-up of non-enhancing gliomas in order to predict grading.

[The development of SPA bone densitometry for heel bone]

The design principles of a bone densitometer for heel bone based on SPA are introduced here, which include the principles of mechanical system and control system. The main technical index and advantages of the device have also been discussed in the paper.

[Preparation, characterization and evaluation of cellulose tris (3,5-dimethylphencarbamate) chiral stationary phase]

With the deposition of cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) on aminopropylated silica gel (mean particle size, 5 microns; pore size, 13 nm; surface area, 110 m2/g) by using two different methods (evaporation and precipitation), two chiral stationary phases (CSP1 and CSP2) characterized by elemental analysis and scanning electron micrography were obtained. They were also evaluated by using seven racemic compounds with n-hexane/ethanol(95/5, V/V) and n-hexane/2-propanol (90/10, V/V) as mobile phases. The results showed that the chiral stationary phase CSP1 obtained by the evaporation method had better efficiency and chiral resolution ability than CSP2 by the precipitation method.

Binding site analysis of c-Myb: screening of potential binding sites by using the mutation matrix derived from systematic binding affinity measurements

The c-Myb oncoprotein is known to bind to multiple sites in the promoters of target genes. We have developed a protocol to screen the binding site of c-Myb by using the systematic binding data derived form measurements of binding affinity for oligonucleotide containing a known Myb-binding site and its complete single mutants. We first applied the method to predict the binding affinity for the known binding sites and compared with available experimental data. The predicated binding sites agree with many putative binding sites of known target promoters. However, there are some binding sites not predicated by the analysis. These sequences deviate from the consensus sequence derived from the binding analyses. In the light of the structure of Myb-DNA complex, these results indicate that different DNA-binding modes may be used by c-Myb to recognize different classes of binding sites. We also screened the sequence database for potential Myb-binding sites, and found sequences of several promoters that have not been identified experimentally but could be the target for c-Myb.