[Relation of pbp2B, ermB, ermA/B, mefA genes with resistance to penicillin and erythromycin among Streptococcus pneumoniae isolates from children].
OBJECTIVE
To investigate the relation of pbp2B, ermB, ermA/B and mefA genes to penicillin and erythromycin resistance among isolated Streptococcus pneumoniae (Sp) in children.


METHODS
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)].


RESULTS
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.


CONCLUSIONS
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.
Ding
Yun-fang
YF
Department of Medical Laboratory, The Children's Hospital Affiliated to Suzhou University, Suzhou 215003, China.
Zhang
Jian-hua
JH
Mi
Zu-huang
ZH
Tao
Yun-zhen
YZ
Qin
Ling
L
D019881:Aminoacyltransferases / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D002648:Child; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics*; D008780:Methyltransferases / Q000235:genetics*; D010403:Penicillin Resistance; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C117866:MefA protein, Streptococcus; D008565:Membrane Proteins; D046915:Penicillin-Binding Proteins; D004917:Erythromycin; D008780:Methyltransferases; C431709:ErmA protein, Bacteria; D019881:Aminoacyltransferases; C478701:penicillin-binding protein 2b, Streptococcus