Nasopharyngeal carriage rate, antimicrobial resistance and serotype distribution of Streptococcus pneumoniae among children with upper respiratory infection / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate nasopharyngeal carriage rate, antimicrobial resistance and serotype distribution of Streptococcus pneumoniae among children with upper respiratory infection.</p><p><b>METHODS</b>Nasopharygeal swabs were collected from children with upper respiratory infection visiting the outpatient department of Beijing Children′s Hospital between March 2013 and February 2014. The antibiotic susceptibility was tested by Etest method, and the serotype was determined by Quellung reaction.</p><p><b>RESULTS</b>The nasopharyngeal carriage rate for Streptococcus pneumoniae was 23.8% (699/2 941). One hundred isolates were randomly chosen for antimicrobial susceptiblity test and serotyping. Up to 98.0% isolates were susceptible to parenteral penicillin. The susceptible rate against oral penicillin, however, was 33.0%. The non-susceptible rate to erythromycin and azithromycin was 97.0%. The multi-drug resistance rate was up to 86.0%. The common serotypes were 6A(12.0%), 19F(12.0%), 6B(10.0%), 23F(9.0%) and 14(8.0%). The coverage rates of 7-, 10- and 13-valent pneumococcal conjugate vaccine were 41.0%, 42.0% and 59.0% respectively.</p><p><b>CONCLUSIONS</b>About 25% of children with upper respiratory infection are nasopharyngeal colonized by Streptococcus pneumoniae. The isolates show a high antimicrobial resistance. The 13-valent pneumococcal conjugate vaccine covers about 60.0% of the isolates.</p>

Characterization of erythromycin-resistant Streptococcus pneumoniae isolates causing invasive diseases in Chinese children / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Erythromycin-resistant Streptococcus pneumoniae isolates that causing invasive pneumococcal diseases (IPD) in Chinese children remain uncharacterized. This study aims to identify the resistance genes associated with erythromycin resistance and to determine the genetic relationships of IPD isolates in Chinese children.</p><p><b>METHODS</b>A total of 171 S. pneumoniae strains were isolated from 11 medical centers in China from 2006 to 2008. All the isolates were characterized via serotyping and antibiotic susceptibility determination. The erythromycin-resistant isolates were further characterized via ermB and mefA gene detection, multi-locus sequence typing analysis, and pulsed-field gel electrophoresis.</p><p><b>RESULTS</b>A total of 164 (95.9%) isolates showed resistance to erythromycin, of which 162 strains with high high-level resistance (MIC ≥ 256 µg/ml). A total of 104 (63.4%) isolates carry the ermB gene alone, whereas 59 (36.0%) harbor both ermB and mefA genes. Of the 59 strains, 54 were of serotypes 19A and 19F and were identified as highly clonal and related to the Taiwan(19F)-14 clone.</p><p><b>CONCLUSIONS</b>The erythromycin resistance rate in IPD isolates is significantly high and is predominantly mediated by the ermB gene. Isolates that carry both ermB and mefA genes are predominantly of serotypes 19A and 19F.</p>

Enterobacterial repetitive intergenic consensus-polymerase chain reaction typing of Escherichia coli isolated from hospitalized neonates / 中华实用儿科临床杂志

Objective To explore the genetic relationship among the isolates of Escherichia coli,and to analyze the epidemiological status.Methods One hundred and ten strains of Escherichia coli were isolated from 102 hospitalized neonates in the Neonatal Center of Beijing Children's Hospital.The homologous relation among the strains were typed and studied by using enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) method.Results One hundred and two cases of neonates were selected,including 61 male cases and 41 female cases.Among them,94 cases were full-term infants,8 cases were preterm infants,25 cases ≤7 days,and 77 cases ＞ 7 days.One hundred and ten strains of Escherichia coli isolated clinically by ERIC-PCR typing were divided into 58 types,fingerprints indnded 4-12 bands,and the similarity coefficient was between 26.2％ and 100.0％.The dominant genotype contained 6 strains,with 4-5 bands,and the similarity coefficient was 88.9％-100.0％.In dominant genotype E58,5 out of 6 strains were attacked in March,and 1 strain attacked by the end of February.In the second dominant type E32,4 out of 5 strains were spread in May,and 1 strain in July.In E23 type,4 out of 5 strains were distributed in September,and 1 strain in October.There were 8 pairs of clinical isolates from 8 neonatal patients,including 7 pairs of them belonging to the same genotype,and the other 1 pair of isolates did not belong to the same genotype and was distantly related.From homology analysis point of view,the possibility of the different isolates was infectious or contaminant.Two strains were isolated from the blood and cerebrospinal fluid of the same patient,belonging to the same genotype,with 100.0％ similarity coefficient.Five isolates were confirmed to have closer relationship by ERIC-PCR genotyping.One isolate derived from a child and the other 4 isolates derived from the other 4 children were considered hospital-acquired infection since these five children shared one ward.Conclusions Escherichia coli infections in full-term infants are more common.Most of them are late infections,and boys are more than girls.Different seasons may have different types of epidemic caused by Escherichia coli infection of respiratory tract.Strains of high homology hospital-acquired infection by Escherichia coli was found at Beijng Children's Hospital had Escherichia coli hospital-acquired infection.ERIC-PCR typing method can track the source of infection,which plays a role in prevention and control of nosocomial infection.

Molecular epidemiology of serotype 19A Streptococcus pneumoniae isolated from children in Beijing, 1997-2006 / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Despite the prevalence of Streptococcus pneumoniae serotype 19A, the molecular characteristics of this serotype are yet to be fully elucidated. The aim of this study was therefore to determine the homology of the serotype 19A in China.</p><p><b>METHODS</b>Pulsed-field gel electrophoresis and multilocus sequence typing were done to these forty-nine serotype 19A isolates to investigate the relationship between the strains prevalent in Beijing and other regions.</p><p><b>RESULTS</b>From 1997 to 2006, the percentage of serotype 19A isolates increased. The susceptibility rate to penicillin and amoxicillin decreased and the resistance rate to cefuroxime increased. ST320 was the most prevalent ST, followed by ST3546. There were six new STs identified in our study. The serotype 19A strains were classified into six different pulsed-field gel electrophoresis (PFGE) patterns. ST320, which was associated with two different PFGE patterns (A and D), accounted for 32 isolates, and ST3546, which was associated with two PFGE patterns (B and E), accounted for eight isolates.</p><p><b>CONCLUSIONS</b>From 2003 onwards, ST320 was the most common ST and the rate of resistance to cefuroxime increased significantly. Further long-term surveys of Streptococcus pneumoniae serotype 19A are required to monitor ST prevalence and antimicrobial resistance in this important human pathogen.</p>

Characterization of multidrug-resistant and metallo-beta-lactamase-producing Pseudomonas aeruginosa isolates from a paediatric clinic in China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>In the present study, we characterized multidrug-resistant Pseudomonas aeruginosa (MDRP) clinical isolates from a paediatric facility and investigated the types and features of the metallo-beta-lactamases (MBLs) produced by carbapenem-resistant strains.</p><p><b>METHODS</b>Four hundred and ninety-eight strains of Pseudomonas aeruginosa were isolated from patients at Beijing Children's Hospital between January 2005 and December 2006. The minimal inhibition concentrations (MICs) of the strains for 13 antibiotics were measured. A combination of the E test and PCR amplification/DNA sequencing was used to define the carbapenem-resistant strains.</p><p><b>RESULTS</b>We found that 24.1% (120/498) of the isolates were MDRP. The frequencies of resistance to imipenem and meropenem were 34.2% and 35.8%, respectively, and the MIC50 and MIC90 values for the two antibiotics were identical at 4 microg/ml and 32 microg/ml, respectively. The detection rate for carbapenem resistance was 49.2% (59/120). Among the 59 carbapenem-resistant Pseudomonas aeruginosa strains, 39 (66.1%) were positive for the MBL genotype; 35 (89.7%) strains carried the bla(IMP) gene and 4 (10.3%) strains carried the bla(VIM) gene. Neither bla(SPM) nor bla(GIM) was amplified from any of the 59 isolates. DNA sequencing revealed that IMP-1 was present in 35 IMP-producing isolates and VIM-2 was detected in four VIM-producing isolates.</p><p><b>CONCLUSIONS</b>These MDRP isolates exhibited high frequencies of resistance to carbapenems among clinical isolates from a paediatric facility in Beijing, China. The production of MBL appears to be an important mechanism for carbapenem resistance in Pseudomonas aeruginosa.</p>

Surveillance of antibiotic resistance of Streptococcus pneumoniae isolated from hospitalized patients with pneumonia in four children's hospitals in China / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the antimicrobial resistance of Streptococcus pneumoniae (S.pneumoniae) isolated from Chinese children with pneumonia.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

Serotype distribution and resistance to beta-lactams of Streptococcus pneumoniae isolated from children in Beijing, Shanghai and Guangzhou, 2000 - 2002 / 中华儿科杂志

<p><b>OBJECTIVE</b>The present study was designed to investigate the situation of serotype distribution and beta-lactam antibiotics resistance of Streptococcus pneumoniae (S. pneumoniae) isolated from Chinese children, and to further understand the significance of vaccine for preventing infection caused by the bactria and controlling the resistance to antibiotics.</p><p><b>METHODS</b>Nasopharageal swab specimens were collected from randomly selected less than 5-year-old out-patients with upper respiratory infection in Beijing, Shanghai and Guangzhou, 2000 - 2002. Capsular typing was performed by the Quellung reaction tested using a simplified chessboard system for typing of S. pneumoniae. The coverage rate of the 7-valent pneumococcal conjugate vaccine (4, 6B, 9V, 14, 18C, 19F and 23F) was calculated. Antibiotic susceptibility was determined by E-test MIC method for beta-lactam antibiotics (penicillin, amoxicillin/clavulanic acid, cefaclor, cefuroxime and ceftriaxone).</p><p><b>RESULTS</b>Totally 625 pneumococcal strains were typed. Serogroup 19, including 121 strains, was the most frequent serogroup observed (19.4%). Other frequently observed serotypes/serogroups in decreasing order of frequency were serotype/serogroups 23 (15.4%), 6 (13.3%), 14 (6.6%) and 15 (4.3%). Of all these isolates, about 57.6% (360/625) were in the 7-valent conjugate vaccine. Only 1, 6 and 12 strains were serotypes/serogroups 4, 9 and 18, respectively. The coverage rate for the 7-valent vaccine of penicillin nonsusceptible S. pneumoniae (PNSP) was higher than penicillin susceptible S. pneumoniae (PSSP) (73.2% and 46.1%). Serogroups 19 and 23, without other serotypes/serogroups, were significantly associated with PNSP (serogroup 19 accounted for 29.1% of PNSP and 12.2% of PSSP; serogroup 23 accounted for 23.8% of PNSP to 9.2% of PSSP). Overall, 140 strains (22.4%) could not be typed by using the chessboard system, and 117 strains (18.7%) were identified as other 28 kinds of serotype/serogroup. The strains showed different resistance change for beta-lactam antibiotics according to different serotype/serogroup during the three years.</p><p><b>CONCLUSIONS</b>Serotype/Serogroup 19, 23, 6, 14 and 15 were the common types among the pneumococcal strains isolated from Chinese children. Serogroups 19 and 23 were significantly associated with PNSP. The 7-valent pneumococcal conjugate vaccine could cover most of the islotes.</p>

Detection of group B streptococcus in the cases died of neonatal pneumonia / 中华儿科杂志

<p><b>OBJECTIVE</b>From the 1970s, group B streptococci (GBS) have been widely recognized as an important pathogen in neonatal infectious disease, and it emerged as the leading cause of neonatal morbidity and mortality in the Western world. However, there are few data on the prevalence of neonatal GBS infections in China. The aim of this retrospective study was to estimate whether GBS is an important pathogen in severe neonatal pneumonia, and to develop a method for detection of GBS infections in fatal neonatal pneumonia.</p><p><b>METHODS</b>A total of 234 neonatal cases (0 - 28 days) died in Beijing Children's Hospital from 1953 to 2004 were enrolled in this study. They were divided into two groups. Two hundred cases diagnosed as neonatal pneumonia were assigned to study group and the remaining 34 cases died of neonatal hemolysis or surgical operation without any confirmed infectious diseases were designated as control group. Formalin-fixed, paraffin-embedded lung tissues were used as source for total genomic DNA extraction. PCR and Southern blot analyses were applied to detect GBS specific cfb gene target sequence. And the clinical data of these cases were reviewed as well.</p><p><b>RESULTS</b>In the study group, 52 cases were detected positive for GBS DNA by PCR (26%), 130 cases were positive by Southern blot (65%). In the control group, 1 case was detected positive GBS DNA by PCR (3%), and 6 cases were positive by Southern blot (18%). The positive rate was significantly lower in the control group than that in the study group (PCR, chi(2) = 8.82, P < 0.01; Southern blot, chi(2) = 26.77, P < 0.01). The positive rate in the neonates younger than 7 days (early-onset) was significantly higher than that in neonates older than 7 days (late-onset) (PCR: 37% vs. 13%, chi(2) = 15.537, P < 0.01; Southern blot: 72% vs. 52%, chi(2) = 4.37, P < 0.05). In the positive early-onset cases, 39% of whom were born prematurely (29/74). Out of the 200 cases, 75 had complete clinical data. Neither blood nor lung culture for GBS was performed in any of these cases. But risk factors were identified for 35 cases, such as premature delivery, low birth weight, premature rupture of the membrane and abnormal amniotic fluid. GBS was positive in all these cases. Severe apnea appeared to be a common symptom and was present in most of the early-onset GBS-positive cases, while cough and wheezing were found in most of the late-onset GBS-positive cases. In the control group, one PCR positive case was suffered from malignant teratoma. The other 5 positive cases confirmed by Southern blot were diagnosed as kernicterus, hepatoma, aproctia complicating with cysti-urethral fistula, neonatal physio logical bleeding and aproctia complicated with archo-perineal fistula.</p><p><b>CONCLUSION</b>Group B Streptococcus is an important pathogen in fatal neonatal pneumonia, especially in early-onset cases. southern blot may be a sensitive method to detect GBS infection in archival tissues. In the clinical work, more attention should be paid to the neonates with GBS risk factors. And GBS detection and prevention in neonates should be put into clinical practice.</p>

Study on Haemophilus influenzae type b: data from autopsy of community acquired pneumonia among children / 中华流行病学杂志

<p><b>OBJECTIVE</b>To evaluate the status of Haemophilus influenza type b(Hib) on death cases of children from community-acquired pneumonia (CAP) and to estimate the value of direct in-situ polymerase chain reaction (ISPCR) on diagnosis of children CAP, pathogenically.</p><p><b>METHODS</b>Ordinary PCR, Southern blot and direct ISPCR were applied and compared in detecting Hib in 100 paraffin-embedded lung tissues of autopsy children died of CAP.</p><p><b>RESULTS</b>No major difference on the detection rate of Hib between 50-60s and 80s-2002 was found. The detection rate of Hib by direct ISPCR was higher than the other two methods. By Southern blot, Hib was identified from 8 out of 100 samples (8%), including 4 out of 56 in 1950-60s (7.1%) and 4 out of 44 (9.1%) (chi2 = 0.084, P>0.05) in 1980s-2002. By ISPCR, Hib was identified from 17 out of 100 samples (17%), including 8 out of 56 in 1950-60s (14.3%) and 9 out of 44 (20.5%) with chi2 = 0.665, P > 0.05, in 1980s-2002. Positive cases diagnosed by both Southern blot and ISPCR were 7%.</p><p><b>CONCLUSION</b>Hib was one of the main bacterial pathogens causing CAP and deaths among children. Direct ISPCR was prefertable to be used in pathogenic diagnosis on children pneumonia, in terms of its sensitivity, specificity and localization.</p>

Molecular epidemiology of penicillin-nonsusceptible Streptococcus pneumoniae in Beijing, China, 2000-2002 / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the molecular epidemiology of the penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) in Beijing, China.</p><p><b>METHODS</b>The resistant profile of 63 PNSP strains isolated from children with upper respiratory infection in the outpatient department from 2000 to 2002 was analyzed. The isolates were compared by detecting restriction fragment length polymorphism (RFLP) of the penicillin-binding protein (PBP) genes pbp1a, pbp2b and pbp2x and by applying chromosomal macrorestriction patterns detected by pulsed-field gel electrophoresis (PFGE).</p><p><b>RESULTS</b>Sixty-one (96.8%) out of the 63 PNSP strains were multidrug-resistant Streptococcus pneumoniae (Sp). Overall, 16 resistance profiles were found, 14 of which were multidrug resistant profiles. Seven (33.3%), 6 (24.0%) and 8 (47.1%) strains resistant to one of cephalosporins were respectively isolated in 2000, 2001 and 2002, indicating an increasing trend but without any statistical significance (chi(2) = 2.42, P > 0.05). The RFLP results showed 8, 9 and 18 genotypes of pbp1a, pbp2b and pbp2x, respectively. A total of 30 patterns were found according to the three pbps types. And clearly, the most common 5 patterns had main resistant profiles. In the mean time, 35 different PFGE types were elucidated and the 9 PFGE types, with each consisting of more than 2 strains, covered 59% (37/63) of all isolates. One of the 9 PFGE type included 2 strains, both possibly related to each other, but one of them was detected to be the same PFGE pattern with clones prevalent in Asia, Vietnam-19 serogroup, Singapore-19 serogroup, Taiwan-19 serogroup, and the other was the same as that in Korea-19 serogroup.</p><p><b>CONCLUSION</b>Multidrug resistance is very common among PNSP isolates in Beijing. The spread of a few multidrug resistant clones is an important factor for the prevalence of PNSP. It deserves the concern that the resistant clones spread in Asia have been found in Beijing.</p>

Genotyping of ampicillin-resistant Haemophilus influenzae / 中华儿科杂志

<p><b>OBJECTIVE</b>Haemophilus (H.) influenzae is a gram-negative bacillus that is a common commensal organism of the human upper respiratory tract and an important cause of human diseases such as pneumonia, meningitis, septicemia, epiglottitis and cellulitis. Strains of H. influenzae are classified according to their capsular polysaccharide. There are six serotypes, designated as a through f. In addition, there are nonencapsulated strains. Although the type of infectious diseases caused by H. influenzae has changed considerably in recent years because of the widespread and routine immunization of children against type b H. influenzae (Hib), Hib remains an important pathogen. Ampicillin is the drug of choice for treating many infections caused by H. influenzae, but its usefulness has been compromised by the increasing prevalence of ampicillin-resistant strains. The continued monitoring of resistant strains by using genotyping methods may provide insights into the epidemiology of transmission. A molecular epidemiological study of ampicillin-resistant H. influenzae derived from nasopharyngeal swabs specimens of children less than 5 years of age with respiratory tract infection were investigated in this study.</p><p><b>METHODS</b>A total of 899 isolates were collected from Beijing, Shanghai, and Guangzhou during 2000-2003. Susceptibility to ampicillin was determined by using E-test. Ampicillin-resistant H. influenzae strains were selected according to National Committee for Clinical Laboratory Standards (NCCLS) 2002 breakpoints. Nested PCR method with primers specific for bexA gene and b capsulate type-specific gene was established. Genotyping by pulsed-field gel electrophoresis (PFGE) and multiplex PCR assay was performed for all ampicillin-resistant H. influenzae strains.</p><p><b>RESULTS</b>Seventy-four ampicillin-resistant H. influenzae strains were obtained. Two strains were positive by nested PCR, characterized as b genotype. The incidence of Hib in ampicillin-resistant H. influenzae strains was 2.7%; 38 genotypes were detected by PFGE. Detection of five types strains of clonal dissemination by PFGE accounted for 55.4% in all ampicillin-resistant H. influenzae strains. Among them eighteen H. influenzae strains belonged to one type, accounted for 24.3% in all ampicillin-resistant H. influenzae strains. Thirty one genotypes were identified by multiplex PCR assay for ampicillin-resistant H. influenzae. The identity ratio of PFGE and multiplex PCR was 63.5%.</p><p><b>CONCLUSION</b>In Beijing, Shanghai and Guangzhou areas 55.4% of ampicillin-resistant H. influenzae strains had clonal dissemination during the 4 years.</p>

Macrolide-resistant Streptococcus pneumoniae in the pediatric population in Beijing / 中华儿科杂志

<p><b>OBJECTIVE</b>To analyze the mechanisms of macrolide resistance in Streptococcus pneumoniae from children in Beijing.</p><p><b>METHODS</b>The MICs of penicillin and erythromycin were determined by the E-test methods for 200 Streptococcus pneumoniae isolates collected from 2002 to 2003 at Beijing Children's Hospital. MICs of azithrhomycin, clarithromycin, acetylspiramycin and clindamycin for 147 erythromycin-resistant isolates were detected by the agar dilution methods. For phenotyping, macrolide resistance induction tests were used in erythromycin-resistant isolates. PCR was used to determine the presence of the erythromycin-resistant genes.</p><p><b>RESULTS</b>Of 200 Streptococcus pneumoniae isolates, 89.5% were resistant to erythromycin. In 147 erythromycin-resistant isolates, resistance rates were as follows: azithromycin, 100%; clarithromycin, 100%; acetylspiramycin, 95.2%; and clindamycin, 95.9%. The most common macrolide resistance phenotype was the cMIS phenotype (95.9%), 1.4% had the iMLS phenotype and 2.7% the M phenotype. Erythromycin-resistant isolates were characterized for the underlying resistance genotype, with 79.6% having the ermB genotypes, 17.7% having both ermB and mefA, 2.7% having the mefA, and none having neither ermB nor mefA genotypes.</p><p><b>CONCLUSIONS</b>The rates of carriage of macrolide-resistant Streptococcus pneumoniae by children were high in Beijing during 2002 - 2003. cMLS was the most prevalent phenotype among erythromycin-resistant Streptococcus pneumoniae isolates, and ribosomal modification (ermB gene coded) was the main resistance mechanism against macrolides in Beijing region.</p>

Analysis of antimicrobial resistance of Streptococcus pneumoniae with restriction fragment length polymorphism of pbp2b gene and pulsed-field gel electrophoresis profiles among children / 中华儿科杂志

<p><b>UNLABELLED</b>Streptococcus pneumoniae is a common cause of potentially life-threatening infections such as meningitis, bacteraemia, pneumonia worldwide, for which children of preschool age are at particularly high risk. Since the late 1970s and 1980s, antibiotic resistance among pneumococci has become an emerging problem. Several multidrug-resistant clones have rapidly spread throughout the world.</p><p><b>OBJECTIVE</b>(1) To investigate the prevalence of penicillin and other antibiotics nonsusceptibility among pneumococci. (2) To analyze the correlation of pbp2b amplicon profiles with penicillin resistance. (3) To serotype 31 isolates of penicillin-resistant pneumococci by latex agglutination. (4) To analyze the chromosomal relatedness of serotype 23F and 6 isolates of penicillin-resistant pneumococci by using pulsed-field gel electrophoresis (PFGE) and characterize these isolates in molecular epidemiology.</p><p><b>METHODS</b>(1) Susceptibility was determined by using broth microdilution, E-test, and K-B disk. (2) The correlation of pbp2b amplicon profiles with penicillin resistance was assessed by restriction fragment length polymorphism (RFLP). (3) Serotyping of penicillin-resistant pneumococcal isolates was performed by using latex agglutination. (4) The properties of serotype 23F and 6 isolates of penicillin-resistant pneumococci were assessed by PFGE.</p><p><b>RESULTS</b>S. pneumoniae with increased nonsusceptibility (including intermediate strains and resistant strains) to penicillin G was 9.9% in 1997, 12.6% in 1998, 14.6% in 2000; to cefuroxime 4.2%, 1.5%, 8.2%; to cefotaxime 0.0%, 1.7%, 1.0% respectively. There were no statistically significant differences (P > 0.05). While resistance to erythromycin, trimethoprim-sulfamethoxazole and chloramphenicol increased significantly from 76.8% in 1997 to 87.4% in 2000, from 74.7% to 88.3%, and from 22.6% to 40.8%, respectively (P < 0.05). RFLP analysis of pneumococcal pbp2b-specific amplicons was effective for screening penicillin resistance. Of the 31 strains of penicillin-resistant pneumococci (MICs 0.12 - 2.0 micro g/ml) studied, 6 (19.4%) strains (MICs 0.12 - 0.19 micro g/ml) were serotype 23F and 3 (9.7%) strains (MICs 0.5 - 1.5 micro g/ml) were serotype 6. There were nearly identical susceptibility to antibiotics and identical PFGE patterns in the former, and there were different susceptibility to antibiotics and different PFGE patterns in the latter. Three serotype 6 strains had different susceptibility to antibiotics and different PFGE patterns, which suggested that those strains may be scattered.</p><p><b>CONCLUSION</b>Generally beta-lactams retained their activity against S. pneumoniae in Beijing. Resistance to erythromycin, trimethoprim-sulfamethoxazole, and chloramphenicol increased drastically. RFLP analysis of pneumococcal pbp2b-specific amplicons was effective for screening penicillin resistance. In 6 strains of serotype 23 F there were nearly identical susceptibility to antibiotics and identical PFGE patterns, which suggested the probability that there was a spread of serotype 23F isolates with low-level penicillin resistance in local area.</p>

Analysis of genotype of metallo-?-lactamases produced by carbapenem-resistant Pseudomonas aeruginosa in pediatric patients / 中华检验医学杂志

Objective To investigate the genotype of metallo-?-lactamases (MBL) produced by carbapenem resistant Pseudomonas aeruginosa in pediatric patients.Methods 59 strains of resistance to imipenem or meropenem were collected from December 2003 to November 2005 in Beijing children's hospital.Isolates were further evaluated for MBL production by two screening methods.MBL Etest strips were used to screen the phenotype of MBL production.Molecular screening for blaVIM,blaIMP,blaSPM and blaGIM was carried out using primers targeting the conserved regions of the MBL genes.The PCR fragments obtained with integron primers were sequenced on both strands.The nucleotide sequences were compared with sequences available over the Internet.Results Of the 59 carbapenem resistant Pseudomonas aeruginosa included in this study,29 (49.2%)were MBL positive using Etest methods,and 39 (66.1%) of these tested positive for MBL genes by PCR.35 (89.7%) were positive for blaIMP genes and 4 (10.3%) were positive for blaVIM genes.All isolates were negative for SPM and GIM DNA sequencing revealed that the IMP-1 was detected in 35 IMP-producing isolates,and VIM-2 was detected in 4 VIM-producing isolates.Conclusions This study has demonstrated that MBL-producing strains in pediatric are more common than in adult.IMP-1-producing strains are the main in pediatric,and VIM-2-producing strains concurred.The production of MBL is one of the important reasons of carbapenem resistant Pseudomonas aeruginosa in pediatric.It is very important to monitor the production of MBL.