Bacterial pathogenic characteristics of respiratory tract infection in children in Suzhou, China: an analysis of 14,994 cases / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the bacterial pathogenic characteristics of respiratory tract infection in children.</p><p><b>METHODS</b>The medical data from 14,994 children with respiratory tract infection who were hospitalized in Children's Hospital Affiliated to Soochow University between November 2005 and October 2014 were retrospectively reviewed.</p><p><b>RESULTS</b>Among the 14,994 sputum samples from the children with respiratory tract infection, 3,947 (26.32%) had a positive bacterial culture. The most common bacterial pathogen was Streptococcus pneumonia (12.79%), followed by Haemophilus influenzae (5.02%) and Moraxella catarrhalis (2.91%). The bacterial detection rates differed significantly in different years and seasons and children of different ages (P<0.01). The children who had not taken antibacterial agents before admission had a significantly higher positive bacterial culture rate than those who had taken antibacterial agents (P<0.01). There were significant differences in the bacterial detection rate among the children with different course of disease (<1 month, 1-3 months and >3 months) (P<0.05). The detection rates of Streptococcus pneumonia, Moraxella catarrhalis and Acinetobacter baumannii showed an increased trend with a prolonged disease course (P<0.05).</p><p><b>CONCLUSIONS</b>Streptococcus pneumonia is the most common bacterial pathogen causing respiratory tract infection in children, followed by Haemophilus influenzae and Moraxella catarrhalis. The detection rate of bacterial pathogens varies in different years and seasons and children of different ages. The course of the disease and application of antibacterial agents outside hospital can affect the detection rate of bacterial pathogens in children with respiratory tract infection.</p>

Urinary tract infections in the neonatal intensive care unit: clinical analysis of 229 cases / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the clinical features, distribution of pathogens, drug susceptibility, and treatment effectiveness in neonates with urinary tract infection (UTI) and admitted to the neonatal intensive care unit (NICU).</p><p><b>METHODS</b>The clinical data of 229 neonates who developed UTI during their stay in the NICU were retrospectively studied.</p><p><b>RESULTS</b>The main clinical manifestations of these children included fever/irregular body temperature, refusing to milk feeding, jaundice, vomiting, diarrhea, poor weight gain, and lethargy. The top three pathogens were Escherichia coli, Enterococcus feces, and Klebsiella pneumoniae. Escherichia coli and Klebsiella pneumoniae were highly resistant to ampicillin and most cephalosporins (≥ 85%), and were highly sensitive to imipenem (100%), meropenem (100%), cefoperazone/sulbactam and piperacillin/tazobactam (>90%). Enterococcus feces were highly resistant to penicillin (100%), rifampicin (84%) and gentamicin (79%), but were sensitive to vancomycin.</p><p><b>CONCLUSIONS</b>The clinical manifestations of neonatal UTI are often atypical and manifested as systemic symptoms. The main pathogenic bacterium is Escherichia coli, and the isolation rate of enterococci can also be high. Most pathogenic bacteria are resistant to penicillin and cephalosporins, and therefore decision-making on drug administration must be based on the results of drug sensitivity tests.</p>

Comparative studies on the composition and antibiotic-resistance of pathogenic bacteria between children with community-acquired and hospital-acquired pneumonia / 中华预防医学杂志

<p><b>OBJECTIVE</b>This research was to explore the difference between children with community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP) in the composition and antibiotic-resistance of pathogenic bacteria.</p><p><b>METHODS</b>241 CAP and 116 HAP with positive sputum culture who were hospitalized from January to December in 2008 in Children's Hospital Affiliated to Suzhou University were selected in this study. The bacteria were identified by traditionally manual method and antibiotic sensitivity tests were performed by K-B method. The chi-square or Fisher's exact test were used for statistical test.</p><p><b>RESULTS</b>In 241 CAP, Streptococcus pneumoniae and haemophilus influenza accounted for (42.2%, 106/251) and (12.4%, 31/251) infection, respectively; however in 116 HAP, Enterobacteriaceae and Non-fermenters accounted for (88.2%, 127/144). In addition, methicillin-resistant Staphylococcus aureus weren't isolated, however, its detection rate was 66.7% in HAP. The drug resistance was 1.5 times higher in HAP than that in CAP for several types of antibiotics, such as ceftazidime (37.5% (6/16) vs 75.6% (31/41)), cefepime (37.5% (6/16) vs 78.0% (32/41)), aztreonam (50.0% (8/16) vs 90.2% (37/41)), cefoperazone/sulbactam (12.5% (2/16) vs 51.2% (21/41)) and piperacillin/tazobactam (12.5% (2/16) vs 56.0% (23/41)). Klebsiella pneumoniae isolated from HAP had higher drug resistance than that isolated from CAP against some antibiotics, for example, gentamicin (0 vs 63.6% (7/11)), SMZ + TMP (20.0% (1/5) vs 63.6% (7/11)) and cefoperazone/sulbactam (0 vs 54.5% (6/11)). We also found Enterobacter cloacae isolated from HAP showed high drug resistance than that isolated from CAP against imipenem (0 vs 46.7% (7/15)), aztreonam (9.1% (1/11) vs 60.0% (9/15)) and cefoperazone (18.2% (2/11) vs 80.0% (12/15)) and Pseudomonas aeruginosa from HAP had higher resistance than that from CAP against gentamicin (0 vs 50.0% (9/18)), amikacin (0 vs 38.9% (7/18)), ceftazidime (0 vs 55.6% (10/18)), cefepime (0 vs 50.0% (9/18)) and cefoperazone (33.3% (2/6) vs 94.4% (17/18)). The detection rates of ESBLs for Escherichia coli were 84.6% (11/13) and 93.3% (14/15) in CAP and HAP, respectively (χ(2) = 0.553, P > 0.05); while for Klebsiella pneumoniae, they were 81.3% (13/16) and 95.1% (39/41), respectively (χ(2) = 2.767, P > 0.05).</p><p><b>CONCLUSION</b>CAP was mainly comprised of Streptococcus pneumoniae and haemophilus influenza; while HAP was mainly comprised of Enterobacteriaceae and Non-fermenters. The drug resistance of gram-negative bacilli was higher in HAP than that in CAP.</p>

Effects of amino acid substitutions of penicillin-binding proteins 2B, 1A, 2X on minimal inhibitory concentration of beta-lactams against Streptococcus pneumoniae / 中华儿科杂志

<p><b>OBJECTIVE</b>To observe the effect of amino acid substitution in conserved sequence of penicillin-binding protein (PBP) 1A, 2B, 2X on antimicrobial activity of beta-lactams against Streptococcus pneumoniae (SP).</p><p><b>METHOD</b>Minimal inhibitory concentration (MIC) of 6 beta-lactams was determined by the E-test in 59 SP strains. The penicillin-binding protein genes pbp1a, 2b, 2x in every SP strain were amplified by nested-polymerase chain reaction (nPCR), then the PCR products were sequenced using automatic genetic analyzer directly. To analyze the amino acid substitutions, the DNA sequences were converted to protein sequences and aligned by Clustalx software. According to amino acid substitution in conserved sequence of PBP2B, 3 phenotypes were observed, including: PBP2B phenotype I (no amino acid substitution); PBP2B phenotype II (Glutamine 432-->Leucine and/or Threonine 445/451-->Alanine/Serine, Glutamic 481-->Glycine, 1 strain had proline insertion between residues 431/432); PBP2B phenotype III (Alanine 624-->Glycine with the addition of phenotype II). According to amino acid substitution in conserved sequence of PBP1A, 3 phenotypes were observed, including: PBP1A phenotype I (no amino acid substitution); PBP1A phenotype II (Threonine 574-->Asparagine, Serine 575-->Threonine, Glutamine 576-->Glycine, Phenylalanine 577-->Tyrosine, 574TSQF-->NTGY); PBP1A III (Threonine 371-->Alanine/Serine, Proline 432-->Threonine with the addition of 574TSQF-->NTGY). According to amino acid substitution in conserved sequence of PBP2X, 4 phenotypes were observed, including: PBP2X phenotype I (no amino acid substitution); PBP2X phenotype II (Histidine 394-->Leucine or Threonine 338-->Alanine); PBP2X phenotype III (Threonine 338-->Alanine, Isoleucine 371-->Threonine, Arginine 384-->Glycine and Leucine 546-->Valine); PBP2X phenotype IV (Methionine 339-->Phenylalanine, Methionine 400-->Threonine with the addition of PBP2X phenotype III).</p><p><b>RESULT</b>Among 59 SP strains antibacterial activities distribution (sensitive strains, intermediate strains and resistant strains) of 6 beta-lactams were penicillin (12, 29, 18); amoxicillin(49, 9, 1); cefuroxime (16, 16, 27); ceftriaxone (47, 1, 11); cefotaxime (47, 3, 9); imipenem (49, 10, 0). beta-lactam antibiotics insensitive strains (intermediate + resistant strain) in PBP2B phenotype III, PBP1A phenotype III, PBP2X phenotype III and IV were significantly increased, the MIC(50) of these strains were significantly higher than that of the others.</p><p><b>CONCLUSION</b>The amino acid substitutions in or vicinal conserved sequence of PBP of SP increase MIC for beta-lactam antibiotics.</p>

Etiology of pneumonia in hospitalized patients less than 3 years of age / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To understand the etiology of pneumonia in hospitalized patients less than 3 years of age.</p><p><b>METHODS</b>A total of 316 children with pneumonia admitted to the Children's Hospital of Suzhou University in Jiangsu Province from March, 2006 to January, 2007 were enrolled in this study. Sputum samples were obtained by deep nasotracheal aspiration technique for bacterial and viral cultures.</p><p><b>RESULTS</b>Of the 316 samples, specific microbial etiology was obtained in 192 cases (60.8%). Bacterial infection was found in 162 cases (51.3 %), viral infection in 19 cases (6.3%)and compound infection with virus and bacteria in 11 cases (3.5 %). Haemophilus influenzae was the most common agent (46 cases; 14.6%) in bacterial infection, followed by Streptococcus pneumoniae (32 cases; 10.1%). Respiratory syncycial virus (RSV) was the most common agent (12 cases; 4.0%) in viral infection, followed by adenovirus (11 cases; 3.6%).</p><p><b>CONCLUSIONS</b>Bacterial infection was a leading cause of pneumonia in children less than 3 years of age in Suzhou area. Haemophilus influenzae was the most common agent, followed by Streptococcus pneumoniae.</p>

Relation of pbp2B, ermB, ermA/B, mefA genes with resistance to penicillin and erythromycin among Streptococcus pneumoniae isolates from children / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the relation of pbp2B, ermB, ermA/B and mefA genes to penicillin and erythromycin resistance among isolated Streptococcus pneumoniae (Sp) in children.</p><p><b>METHODS</b>Twenty-six strains of Sp were collected from September 2002 to April 2003 at the Children Hospital of Suzhou University. (1) Twenty-six pneumococcal isolates were obtained from respiratory tract secretions of children with respiratory diseases. (2) Susceptibility of the isolates to penicillin, cefuroxime, ceftriaxone, cefotaxime and erythromycin was determined by E-test. (3) The genes pbp2B, ermB, ermA/B and mefA of the isolates were detected with PCR. (4) The PCR product of pbp2B gene was sequenced. (5) DNA sequences of pbp2B of pneumococcal isolates were compared with those of SpR6 [penicillin sensitive (www.ncbi.nlm.gov/nucleotide, NC-003098)].</p><p><b>RESULTS</b>Among the 26 isolates studied, pbp2B gene mutation was found in 15(58%) isolates, all were point mutation of A, B, C and D genotypes which were seen in 11(73%), 2(13%), 1(7%) and 1(7%), respectively. The numbers of isolates susceptible to penicillin, cefuroxime, ceftriaxone and cefotaxime were 9(82%), 10(91%), 11(100%) and 11(100%), of 11 non-mutation isolates;numbers of isolates resistant to penicillin, cefuroxime, ceftriaxone, and cefotaxime were 13(87%), 11(73%), 1(7%) and 1(7%) out of 15 isolates with mutation.ErmB, ermA/B, mefA and erm/mef genes were positive in 9(35%), 16(62%), 7(27%) and 21(81%)isolates. MIC of erythromycin was 2 to > 256 mg/L among pneumococcal isolates with erm/mef genes.</p><p><b>CONCLUSION</b>Among antibiotic resistant pneumococcal isolates in the area, the main basis of penicillin resistance was the mutation of pbp2B genes. Genotype A mutation had the highest rate among the isolates with mutation and manifested as resistance to penicillin and cefuroxime. Expression of either all or any of the ermA, ermB and mef genes led to erythromycin resistance. Antibiotics resistant Sp strains in this area are forming a challenge to efficacy of penicillin and erythromycin.</p>

Study on the molecule epidemiological between resistances of 7 genes interrelated 4 antibiotic to isolated Streptococcus pneumoniae in children / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the molecule epidemic for 7 genes interrelated penicillin, erythromycin, tetracycline, vancomycin resistance of isolated Streptococcus pneumoniae (SP) in children at Suzhou area.</p><p><b>METHODS</b>(1) Thirty-one pneumococcal isolates were collected from respiratory tract secretions of children with respiratory diseases from Nov 2002 to Apr 2003 at the Children's Hospital of Suzhou University (reference strain ATCC49619). (2) Penicillin susceptibility was determined by E-test, while erythromycin, tetracycline, vancomycin were determined by K-B disk. (3) The detecting of pbp2B, ermA/B, mefA, tetM, vanA, vanB genes by PCR, Sequencing pbp2B genes, Contrasting pbp2B DNA sequences among pneumococcal isolates and SP R6 [penicillin sensitive (www.ncbi.nlm.gov/nucleotide, NC-003098)].</p><p><b>RESULTS</b>Of thirty-one isolates studied, the results were shown as follows; (1) Penicillin sensibility 38.7% (n = 12), penicillin resistance 61.3% (n = 19), pbp2B mutation 64.5% (n = 20); (2) Erythromycin sensibility 9.7% (n = 3), erythromycin resistance 90.3% (n = 28), ermA/B 71% (n = 22), mefA 32.1% (n = 10), ermA/B + mefA 87.1% (n = 27); (3) Tetracycline sensibility 9.7% (n = 3), tetracycline resistance 90.3% (n = 28), tetM 90.3% (n = 28); (4) Vancomycin sensibility 100% (n = 31), vanA, vanB all 0%.</p><p><b>CONCLUSION</b>Among pneumococcal isolates at our area, penicillin, erythromycin, tetracycline resistance were high, vancomycin was sensitive. Detecting 7 genes interrelated penicillin, erythromycin, tetracycline, vancomycin resistance expressed genotypies for antibiotic resistances in pneumococcal isolates.</p>

Study on the molecular epidemiology of beta-lactamase TEM gene in isolated Streptococcus pneumoniae / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the beta-lactamase TEM gene of isolated Streptococcus pneumoniae (Sp) in Suzhou area.</p><p><b>METHODS</b>Twenty-three strains of Sp were collected from respiratory tract secretions of children with respiratory diseases in Nov 2002 to Apr 2003 at Children's Hospital of Suzhou University (reference strain ATCC49619) to build TEM polymerase chain reaction (PCR) system (reference strain E. coli. 9-j53R1 with TEM gene) TEM gene of 23 strains was detected to comparo the sequences with published TEM gene sequences in GenBank for analyzing TEM gene model.</p><p><b>RESULTS</b>Twenty-one strains had TEM gene with a positive rate of 91.3% (21/23). TEM-129 gene were confirmed from No.17 (SR017, penicillin resistance) TEM sequence. New discovered TEM-129 sequence had a modification (ATG[M]-->ATA[I]) at No.182 code and published (GenBank: www.ncbi.nlm.nih.gov/nucleotide, AY452662). TEM-1 genes were confirmed from other TEM sequences. New discovered TEM-1 gene of isolated Sp had been published (GenBank: www.ncbi.nlm.nih.gov/nucleotide, AY392531) too.</p><p><b>CONCLUSION</b>Isolated Sp had TEM gene (TEM-129, EM-1 genotype) with a positive rate of 91.3%. The result enriched the understanding of isolated Sp with penicillin resistance.</p>