Infection with resistant bacteria has been a great challenge to human health in this new century. WHO document “The global strategy for containment of antimicrobial resistance” emphasized the importance of surveillance on bacterial resistance. In this article some problems existed in resistance surveillance are pointed out, and proposals for the improvement of this work are suggested.

Objective To investigate bacterial resistance of Streptococcus pneumoniae against erythromycin and clindamycin, and resistance phenotypes of erythromycin resistant S. pneumoniae. Methods The MICs of erythromycin and clindamycin against 345 strains of S. pneumoniae were tested with agar dilution method, the phenotypes of erythromycin resistant S. pneumoniae were detected by double disc test. Results The resistance rates of S. pneumoniae to erythromycin and clindamycin were 53.0%(183/345) and 49.6%(171/345), respectively. Among erythromycin resistant S. pneumoniae , the percentages of cMLS, iMLS and M phenotype were 90.3% (159/176), 5.7% (10/176) and 4.0%(7/176), respectively. Conclusions The resistance rate of S.pneumoniae against erythromycin is very high in Shanghai. The main phenotype is cMLS.

Objective To investigate the ESBL gene in a Klebsiella pneumoniae strain isolated from a patient in Huashan Hospital, Shanghai. Methods ESBL gene in the transconjugant from Klebsiella pneumoniae isolate was amplified by PCR. The PCR products were cloned into pHSG398 vector. The antibiotic susceptiblity and ?-lactamases activity of the clone strain were tested; The PCR product was sequenced and analyzed. Results The ESBL gene was identified as CTX-M-12 gene and CTX-M-12 is much more active against cefotaxime than against ceftazidine.Conclusions A clinical isolate of Klebsiella pneumoniae k99-442 isolated from a patient in Huashan Hospital, Shanghai produced ESBL type CTX-M-12 which caused this isolate resistant to most ?-lactams.

Objectives To identify the spectrum of pathogens causing bloodstream infection and their resistance profiles. Methods We examined records with positive blood culture from Jan. 1998 to Mar. 2003 in a teaching hospital in Shanghai. The contaminants were excluded according to the CDC definition of bloodstream infection. Bacteria were collected from April 1, 2002 to March 31, 2003 and MIC to the most commonly used antimicrobial agents was performed. Results 276 episodes occurred during the study period. Of all the BSI episodes, about 74.3% BSI were hospital-acquired and 37.3% were community-acquired. Gram-positive organisms accounted for 38% of isolates, while gram-negative for 44.2% and fungus for 13.8%. The commonest pathogens causing bloodstream infection in hospital-acquired BSI were coagulase-negative staphylococcus (16.9%) and Escherichia coli (16.6%), followed by Candida species (14.1%), Staphylococcus aureus (13.7%) and Klebsiella pneumoniae (13.2%). Streptococcus spp., Escherichia coli, coagulase-negative staphylococcus and Staphylococcus aureus are the leading pathogens causing community-acquired bloodstream infection, which accounted for 16.9%, 15.5%, 15.5%, 11.3% respectively. Susceptibility tests in vitro shows that methicillin resistance in S. aureus was 56%, while in coagulase-negative staphylococcus was 88%. Among the prevalent Gram-negative BSI isolates, resistance rates for most of the antimi-crobial agents were high. However, it is encouraging to note that the carbapenems retained potency against almost all the Enterobacteriaceae, including those resistant to the third-generation cephalosporins and extended-broad-spectrum penicillins. The crude mortality rate of BSI was 24.4%. Conclusion The rate of Coagulase-negative staphylococcus, Klebsiella pneumoniae and fungus in BSI have increased in the past years. Enterobacteriaceae, acinetobacter spp and fungus are more common in hospital-acquired BSI than community-acquired BSI.

Objective To study dIe ESBLs and plasmid-mediated AmpC enzymes in E.Coli and Klebsiella spp. with CLSI ESBL-screening test positive,confirmation test negative but cefepime susceptible.Methods Antimierobial susceptibility testing were performed by Kirby-Bauer(K-B)method.The genes encoding ESBLs and plasmid-mediated AmpC enzymes were detected by PCR Transfer of ESBLs or plagmid-mediated AmpC resistance was studied by conjugation experiments.The homology of donor (E.coli),recipient(E.coli J53)and their transconjugants were analyzed by ERIC-PCR DNA fingerprints of E.coli and Klebsiella pneumoniae were analyzed by PFGE as recommended bv PulseNet protocoL Results Of 18 isolates from Huashan Hospital,11 were E.coli.6 were Klebsiella pneumoniae and 1 was Klebsiella oxytoca.Antimicrobial susceptibility testing indicated all of 18 isolates were positive on the CLSI ESBL screening test but negative on the confirmation test.and all of isolates were susceptible to cefepime(a zoneof-inhibition diameter of≥18 mm wag considered to indicate susceptible).PCR results indicated that 9 of the 11 E.coli isolates predued CMY-2 AmpC enzyme.TEM,SHV,CTX-M,PER,VEB or SFO type β-lactamages were not identified.Of 6 Klebsiella pneumoniae isolates.5 were DHA-1 AmpC-producing strains.4 of the 5 DHA-1 AmpC-producing strains were coexistence of broad-speetrumβ-lactamaae or extended-spectrumβ-lactamase.including two producing SHV-11 and two producing CTX-M-14 and SHV-62 type ESBL respectively.One Klebsiella oxytoca wag also DHA-1 AmpC producing strain.Conjugation experiments indicated that both ESBLs and AmpC enzymes could be transfefred from donor to recipient.PFGE indicated that the DNA fingerprints of K.pneumoniae were difierent but seven CMY-2 AmpC-producing E.coli isolates from general surgieal ward were similar.Concluslons The main mechanism of antibiotic resistance in CLSI ESBLs-screening test-positive but eefepime.susceptible E.coli and KIebsiellaspp.is production of plagmid-mediated AmpC enzymes.Some strains produce both AmpC enzyme and ESBLs.Such strains should be reported as resistant to cefepime.The results suggest that laboratories should routinely conduct research on the ESBLs and plnsmid.mediated AmpC enzymes in Enterobacteriaceae in order to report antimicrobial susceptibility testing results more correcdy.

Objective To investigate acquired carbapenemases and prevalence of carbapenem- resistant gram-negative bacill.Methods The antimicrobial susceptibility was determined by agar dilution method.Metallo-B-lactamase(MBLs)were screened by EDTA-disk synergy tesL The encoding genes of MBLs were amplified by PCR followed by sequencing.Strain homology Was investigated by pulsed-field gel electronphoresis(PFGE).Results In 141 carbapenem-resistant Pseudomonas aeruginosa(P.aeruginosa), there were three resistant patterns which were imipenem(IMP)-resistant+meropenem(MEM)-resistant (66.7%),IMP-resistant+MEM-sensitive(32.6%),and IMP-resistant+MEM-sensitive(0.7%).AⅡthe carbapenem-resistan Acinetobacter baumannii(A.baumannii),Acinetobacter lwoffi(A.lwoffi),Citrobactor freundii(C.freundii),Klebsielta pneumoniac(K.pneumoniac)and Serratia were resistant to imipenem and meropenem.Four strains of 141 P.aeruginosa were positive by EDTA-disk synergy test,and they produced VIM-2-type Metallo-B-1actamase.Of 34 carbapenem-resistan A.baumannii,30 strains produced OXA-tllrpe.Among them, OXA23, OXA24 and OXA66 accounted for 79.4%,38.2% and 67.6%,respectively.And 22 of 34 strains(64.7%)produced multiple OXA-carbapenemases.All 7 strains A.lwoffi produced OXA-23-type carbapenemases.A11 11 strains C.freundii,5 strains k pneumoniac and 1 strains Serratia produced KPC-2-type carbapencmases.And 6 of 11 strains C.freundii produced new subtype IMP-8.Of 15 PFGE type in 34 strains A.baumannii,14 strains belonged to A-type,7 strains belonged to B-type.Seven A.lwoffi strains distilbuted in difierent PFGE type.Four strains of P.aeruginosa producing VIM-2.type Metallo-8-lactamase did not have the same PFGE type.Eleven C.freundii strains had the same PFGE type.Five k pneumoniae strains had the sanle PFGE type.Conclusions Drug resistance to 12 common antibiotics in carbapenem-resistant gram-negative bacill was higher than non-carbapenem-resistant gram-negative.The former produced many kinds of carbaponemases and the strains prducing carbapenemases were prevalent in the C.freundii, A.baumanii, and k pneumoniae.

OBJECTIVE To characterize clinical feature,frequency of isolation and antimicrobial susceptibility of bacterial pathogens isolated from patients with healthcare-associated bacterial meningitis(HABM).METHODS We review the charts of all patients in whom the diagnosis was based on(national) diagnostic criteria of healthcare-(associated) infections at Huashan Hospital from 1995 through 2004.The pathogens were routinely isolated,(identified) and susceptibilities against antimicrobial agents were determined by Kirby-Bauer methods.RESULTS During the 10-year study period,109 patients were treated for 120 episodes of HABM.Most of patients had a(history) of recent and remote neurosurgery.Fever was present in all patients,while nuchal rigidity and decrease consciousness were present in less than half of all patients.CSF opening(pressure,) white blood cell count and(protein) were elevated with predominance of neutrophils.A total of 120 strains were isolated from CSF specimen,Gram-positive bacteria and Gram-negative bacilli were accounted for 35.8% and(64.2%) of all isolates,respectively.Acinetobacter spp(24.2%),coagulase-negative staphylococci(22.5%),Klebsiella pneumoniae(12.5%),Pseudomonas aeruginosa(10%),Enterobacter cloacae(8.3%) and Staphylococcus aureas(7.5%) were the 6 most frequent isolates and resistance to the first line antibiotics was common among all pathogens isolated.(CONCLUSIONS) The most common risk factor for HABM is neurosurgery.Gram-negative bacilli and staphylococci are important causes of HABM,resistance to the first line antibiotics is common among all pathogens isolated.

Objective To investigate the drug resistance of bacteria from January 1 st to December 31 st , 2002. Methods Antimicrobial susceptibility testing of clinical isolates were performed using Kirby Bauer methods and the results were analysed according to NCCLs(2002). Results Of 22 849 clinical isolates, Gram positive organisms accounted for 30.4% (6490 isolates), Gram negative organisms for 69.6% (15 909 isolates). Methicillin resistant Staphylococcus (MRSA) and Methicillin resistant and Coagulase Negative Staphylococci (MRCNS) accounted for 68.2% and 75.3% of staphylococcus aureus respectively. Penicillin nonsusceptible (PISP+PRSP) strains were 40% and 7.5% from children and adult respectively, and 28.9% of them were resistant to cefotriaxon, one of the third generation cephalosporins. Vancomycin is the most potent antimicrobial against Gram positive cocci and non VISA, VRSA and VRE strains has been found yet. The antibacterial activity of antimicrobial agents tested against strains of Gram negative bacilli. ESBLs producing strains accounted for 24.0% and 35.2% of E.coli and Klebsiella spp. respectively. The incidence of ESBLs was increased in recent years. The resistant rates of clinical isolates from in patients to antimicrobial agents were much higher than from out patients. The difference between those was significant. Conclusions Our data will be useful for reasonably choosing antimicrobial agents in the treatment of infections caused by pathogenic bacteria.

Objective To analyze the 23S rRNA gene partial sequences of common bacteria, and establish molecular biologic techniques to identify bacteria by the difference of gene sequences. Methods Analyzing the sequences of variable region of bacterial 23S rRNA genes, primers and oligonucleotide probes were designed accordingly. Thereafter, bacteria were identified by PCR gel electrophoresis and PCR reverse hybridization. Results There exists significant sequence difference between Gram negative bacteria and Gram positive bacteria and it could be used to differentiate these 2 kinds of bacteria quickly with PCR gel electrophoresis. Meanwhile, sequence variety in different species of bacteria was also observed and PCR reverse hybridization could be used to identify different bacterial species further.Conclusions There exist significant sequence differences among 23S rRNA genes in different common bacteria. By the sequence differences, a specific, sensitive and rapid molecular biologic techniques could be established to quickly identify the pathogens of bacterial infections.

20 antimicrobial agents were determined by Kirby-Bauer methods by the participating institutions.RESULTS A total of 428 strains were isolated,Gram-positive cocci and Gram-negative bacilli accounted for 49.8% and 50.2%,respectively.The Gram-positive bacteria increased from 44.6% to 51.2% from 1995-1996 through 2003-2004 and Gram negative bacteria decreased from 55.4% to 48.2% in the meantime.The most frequent Gram-positive isolates were coagulase negative staphylococci,Staphylococcus aureus,Enterococcus spp and Streptococcus pneumoniae;the most frequent Gram-negative isolates were Acinetobacter spp,Klebsiella spp,Escherichia coli,Pseudomonas aeruginosa and Enterobacter spp;Neisseria meningitidis,Haemophilus influenzae,Flavobacterium spp and Citrobacter spp were relative less common.No strains resistant to vancomycin were found in staphylococci and enterococci.Gram-negative bacilli were highly susceptible to carbapenem.CONCLUSIONS Gram-positive cocci play an increasing role in central nervous sysytem infections,especilly coagulase negative staphylococci,and Gram-positive cocci have been increasing from 1995-1996 through 2003-2004,resistance to the first line antibiotics is common among all cerebrospinal fluids isolates.