Genomic analysis of penicillin-resistant Streptococcus pneumoniae in Southeastern Michigan.
OBJECTIVE
The emergence of multidrug resistance within Streptococcus pneumoniae population was analysed, correlating penicillin resistance Pen(R) with secondary antibiotic resistance, capsular serotype, and genetic diversity among isolates.


METHODS
DNA fingerprinting, following macro-restriction enzyme digestion and pulse field gel electrophoresis (PFGE), and restriction fragment analysis of the PBP 2b gene, following PCR amplification, were performed on the Pen(R) S. pneumoniae, among 377 clinical isolates obtained from the clinical microbiology laboratory (University of Michigan Medical Center).


RESULTS
Overall 35% of the isolates were Pen(R) of which 45% demonstrated high-level penicillin (Pen(R)-R, MIC>1). Respiratory isolates were more likely to be Pen(R) (p <0.001) than non-respiratory isolates and the rate of Pen(R)-R was significantly increased in children <10 years of age (59.6%, p <0.02). Secondary antibiotic resistance was more frequently associated with Pen(R)-R. Genomic DNA fingerprinting analysis and restriction fragment analysis of the PBP 2b gene demonstrated genomic divergence with discrete conserved pattern in the PBP 2b gene among the resistant isolates.


CONCLUSIONS
The emergence of multidrug resistance in the S. pneumoniae population in SE Michigan is not due to expansion of a single or limited number of resistant clones, is occurring most frequently in the paediatric population and is associated with a decreased susceptibility to penicillin.
Yee
Elizabeth K
EK
Divisions of Pediatric Infectious Diseases, Department of Pediatrics University of Michigan, Ann Arbor, MI 48109-0244, USA.
Melkerson-Watson
Lyla J
LJ
Bloch
Craig A
CA
Pierson
Carl L
CL
Blackwood
R Alexander
RA
D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D016009:Chi-Square Distribution; D016172:DNA Fingerprinting; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D014644:Genetic Variation; D006602:Hexosyltransferases / Q000235:genetics; D006801:Humans; D008824:Michigan; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics; D010403:Penicillin Resistance / Q000235:genetics; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases / Q000235:genetics; D012150:Polymorphism, Restriction Fragment Length; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase