50%-70%
60 50 40 30 20 10 0 1980's 1990's 2000'
35%-60%
5%-24%
Mechanism of MRSA

MRSA contain novel PBP2a, substitutes for native PBPs; low affinity for all -lactams PBP2a is encoded by mecA gene; expression controlled by mecI, mecR1 and other factors
l l z me em in me in Su Su Ta in ac SM e m n im ne pi ll ll xi p/ P/ p/ en ci id pe fe ip xa ci ci ta Am CF Pi az ro Ce Im lo pi ra fo Am ik ZTM P
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Am
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Wang F. Chin J Infect Chemother 2006; 6: 289
pr
of
Antimicrobial resistance rates of K. pneumoniae in China in 2005 (n=2234)
100 90 80 70 60 50 40 30 20 10 0
68 60
3 13
3 13
0 0
34
124 69
9
70 20
9
42 17
0
28 3
PNSSP, penicillin non-susceptible S. pneumoniae; PISP, penicillin intermediate S. pneumoniae; PRSP, penicillin resistant S. pneumoniae
Clinical
151
79 244 553
15
14 14 14
*
15
11 13 12
0
2 1 2
1997* 99-00
Children
Carriage Clinical
PNSSP, penicillin non-susceptible S. pneumoniae; PISP, penicillin intermediate S. pneumoniae; PRSP, penicillin resistant S. pneumoniae
First case of PRSP
Penicillin resistance in S. pneumoniae in China in late 1990’
Year Region Populati on Adults Source Clinical Clinical Carriage Clinical
Year 2001 01-02 00-02 Region Shanghai
Beijing Shenyang
Populati on Children
Source Clinical Clinical
No. of Strains
PNSSP (%)
PISP (%)
PRSP (%)
100 192 887 624
The penicillin resistance rates were much higher in children than that in adults
Year Region Populati on Adults 96-99 Shanghai Children Adults 2004 Shanghai Children 2004 Multiple centers Adults Clinical Clinical Clinical Clinical Source Clinical No. of Strains PNSSP (%) PISP (%) PRSP (%)
• Streptococcus pneumoniae • Staphylococcus spp.

Gram-negative bacilli
• Enterobacteriaceae

Escherichia coli Klebsiella spp. Enterobacter spp., et al.

Active efflux
• Phenotype M 4% (7/176)
Antimicrobial Resistance in Staphylococcus spp.
Trends of methicillin resistant Staphylococcus spp. (MRS) in China
Increasing trends of Penicillin
resistance in S. pneumoniae in China
70 60 50 40 1 30 49 20 10 0 34.7 50 6 11
70 60 50
R I
40 5 30 2 20 10 0 23 25 31 0
R I
Antimicrobial Resistance in Enterobacteriaceae
Antimicrobial resistance rates of E. coli isolated in China in 2005 (n=3758)
90 80 70 60 50 40 30 20 10 0
• Non-fermenting gram-negative bacilli (non-fermenters)
Antimicrobial Resistance in Streptococcus pneumoniae
History of studies on antimicrobial resistance on Streptococcus pneumoniae
Am
pe
Ce
Ce
Pi
Wang F. Chin J Infect Chemother 2006; 6: 289
1967 1970 1978 1980 1991
Global problem
2001
Regional problem
Spread around the world β-lactams (penicillin) Mechanism of PRSP First case of MDR Macrolides Fluoroquinolones
2000
2001
2002
2002
2003
2004
Shanghai
100 strains each year
Beijing
More than 100 strains each year
Clinical strains isolated from Children’s Hospital
Reasons causing the rapid increasing of penicillin resistance
Resistance of S. pneumoniae to macrolides
70%-90% of S. pneumoniae clinical isolates were resistant to erythromycin
Antimicrobial resistance of S. pneumoniae isolated from children in Beijing, Shanghai, Guangzhou and Xi’an（2000－2001）
55 43 40 41
49 32 34 37
6 11 6 4
3 centers
Children
Clinical
00-01
4 centers
Children
Clinical
PNSSP, penicillin non-susceptible S. pneumoniae; PISP, penicillin intermediate S. pneumoniae; PRSP, penicillin resistant S. pneumoniae
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ft
Me Ci
Guangzhou
No. of Strains
PNSSP (%)
PISP (%)
PRSP (%)
68 60
3 13
3 13
0 0
96-99
1998 1998
Shanghai
Children Children
222
102
14
12
14
12
0
0
Children
Bejing 4 centers
Carriage
Ce f ur ox
Ce ftr i ax
Am ox
Ce f ac
r om yc
Er yth
Te
tra c
yc lin
on
e
v
Mechanism of bacterial resistance: Mosaic PBP Genes in PRSP

Penicillin resistance is due to alterations in endogenous PBPs

Summary
Antimicrobial resistance in gram-positive cocci