Antibiotic resistance and class 1 integron patterns of non-typhoidal human Salmonella serotypes isolated in Hungary in 2002 and 2003

The antibiotic resistance profiles of 5178 Salmonella strains representing 19 non-typhoidal serotypes isolated from human salmonellosis cases in Hungary in 2002 and 2003 were analysed for resistance to 10 antibiotic agents. The most frequent resistances were to nalidixic acid (Nx), streptomycin (S), tetracycline (Tc), ampicillin (Amp) and chloramphenicol (Cm) (ranging from 27% to 13%). Forty-five percent of the Salmonella Typhimurium strains were multiple resistant and belonged mainly to the definitive phage types 104 and U302. A prevalence of 83-94% of strains of serotypes S. Infantis, S. Hadar and S. Virchow was observed with the NxSTc resistance pattern, sometimes complemented with other resistances. Multiple resistance was uncommon in S. Enteritidis; nevertheless, 20% of the strains, most of which belonged to phage type 4, were nalidixic acid resistant. One strain of S. Typhimurium was found to be resistant to ciprofloxacin. Four S. Typhimurium strains were resistant to cefotaxime and produced extended-spectrum beta-lactamase. Selected isolates were screened for the presence of class 1 integrons by polymerase chain reaction (PCR). Nucleotide sequencing of the PCR products revealed nine different variable regions. One resistance gene was identified in five variable regions (aadA1, aadA2, aadA23, dfrV and pse-1), and four variable regions carried two resistance gene cassettes (aadB-catB3, dhfrI-aadA, dfrA17-aadA5 and oxa-1-aadA1).     

Emergence of multidrug-resistant Salmonella enterica serovar Typhi associated with a class 1 integron carrying the dfrA7 gene cassette in Nepal

A total of 121 Salmonella enterica serovars Typhi and Paratyphi A isolated from enteric fever patients at a university hospital in Nepal between February 2004 and January 2006 were tested for their antimicrobial susceptibility. The occurrence and cassette content of integrons as well as the molecular mechanisms of resistance among the multidrug-resistant (MDR) S. Typhi were evaluated. Thirty-nine percent of the isolates were susceptible to all the antimicrobial agents tested. Seven of the S. Typhi strains were MDR. None of the 121 S. enterica isolates were resistant to ciprofloxacin, cefazolin, rifampicin or kanamycin. All MDR S. Typhi isolates contained a class 1 integron with a single cassette, dfrA7, conferring resistance to trimethoprim. Pulsed-field gel electrophoresis (PFGE) of XbaI-generated genomic restriction fragments yielded 12 different patterns. Five of the seven MDR isolates containing class 1 integrons had an identical PFGE pattern. Resistance to sulfamethoxazole, streptomycin, ampicillin, tetracycline and chloramphenicol was mediated by sul1, strA-strB, blaTEM-like, tetB and catA genes, respectively. To the best of our knowledge, this is the first report of integron-associated multidrug resistance as well as the first molecular characterisation of the mechanism of resistance of S. Typhi isolated from Nepal. This study indicates the spread of integron-associated multidrug resistance in S. Typhi in Nepal.     

Antimicrobial susceptibility phenotypes, resistance determinants and DNA fingerprints of Salmonella enterica serotype Typhimurium isolated from bovine in Southern Japan

A longitudinal study was conducted in cattle to determine the antimicrobial resistance phenotypes, integron elements, resistance genes and pulsed-field gel electrophoresis fingerprints among Salmonella enterica serotype Typhimurium isolates. A total of 33 strains were isolated and categorised into Groups A, B and C during the period 1989-2004. Thirty-one strains (93.9%) showed resistance to ampicillin (A) encoded by bla(OXA-1), bla(TEM) and bla(PSE-1) genes; 84.8% showed resistance to chloramphenicol (C) encoded by floR and catA1; 97.0% were resistant both to streptomycin (S) and sulfamethoxazole (Su), the former encoded by aadA1 and aadA2; 100% were resistant to oxytetracycline (T) encoded by tetA, tetB and tetG; and 42.4% were resistant to kanamycin (Km) encoded by aphA1-Iab. Multidrug resistance types observed were ACSSuT-Km (n=13), ACSSuT (n=15), ASSuT (n=3) and SSuT (n=2). Class 1 integrons ranging from 1.0 kb to 1.9 kb were detected from 54.5% of isolates (18/33). Integrons were not detected initially (1989-1992), then during the 1993-1996 interval a high frequency of 1.0 kb and 1.2kb amplicons were detected and during 2000-2004 the amplicon size increased to 1.7 kb and 1.9 kb. We report evidence of additional integration of resistance gene cassettes as shown by integrons with increased size. Finally, group B strains showed banding patterns indistinguishable from S. Typhimurium DT104 reference strain, indicating that the DT104 lineage existed on the island since 1993.     

Molecular basis of resistance to macrolides, lincosamides and streptogramins in Staphylococcus saprophyticus clinical isolates

The aim of this study was to evaluate the prevalence of resistance to macrolide-lincosamide-streptogramin (MLS) antibiotics as well as to assess the molecular basis of this resistance amongst 72 Staphylococcus saprophyticus urinary isolates collected from 2005 to 2009 in University Hospital of Caen (France). Of the 72 strains studied, 33 (45.8%) were resistant to at least one MLS antibiotic, including 24 (72.7%) with an M phenotype, 5 (15.2%) with an inducible MLS(B) phenotype, 3 (9.1%) with a combined M+L phenotype and 1 (3.0%) with an L phenotype. All isolates were susceptible to the combination of streptogramins A and B. The resistance genes erm(A), erm(B), erm(C), msr(A) and lnu(A) were detected alone in 0, 0, 5 (15.2%), 24 (72.7%) and 1 (3.0%) of the 33 MLS-resistant isolates, respectively, whereas 2 strains (6.1%) were positive for both msr(A) and lnu(A). All msr(A)-positive isolates exhibited an M phenotype, whereas all five erm(C)-positive and all three lnu(A)-positive strains displayed, respectively, an inducible MLS(B) phenotype and an L phenotype with a positive Hodge test. Plasmid analysis indicated that erm(C) and lnu(A) genes were borne by small-size plasmids (ca. 2.5 kb), whereas larger plasmids (30-90 kb) harboured msr(A). In conclusion, these findings show a high prevalence of MLS resistance in S. saprophyticus, which was mainly associated with the presence of the msr(A) gene. Since S. saprophyticus colonises the gastrointestinal tract, it may constitute an unexpected reservoir for MLS resistance genes, in particular msr(A), amongst coagulase-negative staphylococci.     

Transferable antibiotic resistance in Escherichia coli isolated from healthy Nigerian school children

Three hundred and ninety-six E. coli isolates obtained from apparently healthy school children in Ile-Ife, Nigeria, were tested for their susceptibility to 11 different antibiotics. Of these, only gentamicin, cefotaxime and nalidixic acid were found to have significant in vitro activity against most of the isolates. The incidence of antibiotic resistances encountered varied between 24% for trimethoprim and 55.5% for the sulphonamide. It was further observed that 47.5% of the isolates were identified as being multiply resistant, since they were simultaneously resistant to at least three different antibiotics. The 86 trimethoprim-resistant isolates tested were found to be able to transfer this resistance trait together with resistance genes of to other antibiotics, into a plamidless strain of E. coli by conjugation. Seventy-seven of the trimethoprim-resistant isolates were also found to be classifiable into the types of dihydrofolate reductases responsible for the observed resistance on the basis of hybridization experiments. The results of this study indicate that there is a large reservoir of antibiotic resistances within the community, and that the resistance genes were easily transferable to other strains even without direct exposure to antibiotics.     

淋病流行株耐药基因的定位研究

为了对淋病流行株的耐药基因作定位研究 ,对 1998～ 1999年间从广东省湛江地区分离出的 98株淋病流行株 ,采用 K- B法测定了其对 10种抗生素的敏感性 ;应用碱裂解法提取了相应菌株的质粒 ;并筛选其中的 NG4 、NG31 、NG4 3、NG70 4株菌作质粒的转化、接合及消除试验 ,对耐药基因进行定位。结果显示 ,98株淋病流行株对环丙沙星、四环素、氯霉素高度耐药 ,耐药率分别为 82 .6 5 %、6 9.39%、5 0 % ;检出 4 2 .5、39.5、7.4、4 .2 kb质粒分别占 11.2 2 %、4 1.82 %、5 9.16 %和 6 7.32 %。 NG4 3能通过接合、转化将对四环素和氯霉素的耐药性传递给受体菌淋病奈瑟氏敏感菌和大肠埃希氏菌 C6 0 0 ,NG31 通过接合传递实验 ,将对氯霉素的耐药性传递给淋病奈瑟氏标准敏感菌 ,通过质粒消除 ,上述菌株又恢复对抗生素的敏感性 ,而环丙沙星的耐药性通过接合、转化及消除均未见改变。从而提示湛江地区淋病流行株耐药形势严峻 ,淋球菌对四环素和氯霉素的耐药由质粒介导 ,对环丙沙星的耐药则有可能由染色体介导。     

Characterisation of plasmids encoding CTX-M-3 extended-spectrum beta-lactamase from Enterobacteriaceae isolated at a university hospital in Taiwan

CTX-M-3 is the most common extended-spectrum beta-lactamase produced by Enterobacteriaceae in Taiwan. The present study was conducted to characterise the genetic environment surrounding bla(CTX-M-3). A total of 11 ceftriaxone-resistant isolates were studied: Escherichia coli (n=4), Klebsiella pneumoniae (n=5) and Salmonella enterica serotypes Anatum (SA831R) and Potsdam (SC72). Molecular methods used included polymerase chain reaction, sequencing, DNA-DNA hybridisation, conjugation, physical mapping and restriction fragment length polymorphism (RFLP) analysis. All isolates examined carried bla(CTX-M-3) on large plasmids (>70kb). The resistance plasmids of the two Salmonella and two K. pneumoniae strains (KP104 and KP116) were confirmed to be conjugative in vitro. RFLP analysis indicated that the plasmids were different. Physical mapping also revealed the difference between the two Salmonella plasmids, pSA831R (82kb) and pSC72 (74kb). An insertion sequence, ISEcp1, was found upstream of each bla(CTX-M-3) gene. However, sequencing of downstream regions of the bla genes showed two different patterns: the presence of orf477 in pSA831R and of orf1-mucA in pSC72, pKP104 and pKP116. IncI1-type oriT and nikA sequences were present in the plasmids of all the clinical isolates tested, except S. Anatum. Different bla(CTX-M-3)-carrying plasmids were identified among the enterobacteria studied. The presence of ISEcp1 in all isolates may be associated with the widespread resistance among Enterobacteriaceae. Although the plasmids were not identical, they appeared to belong to the same incompatibility group (IncI1-like plasmids), suggesting that they are genetically related but may have evolved divergently over time.     

Dissemination of genetically related IMP-6-producing multidrug-resistant Pseudomonas aeruginosa ST235 in South Korea

The present study aimed to describe the prevalence and molecular epidemiology of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa isolates obtained from non-tertiary care hospitals and geriatric hospitals in South Korea. Of the 644 isolates, 224 were carbapenem-resistant, amongst which 41 (18.3%) were MBL-producers and the major MBL type was IMP-6 (35 isolates). IMP-6-producing isolates were multidrug-resistant and showed higher minimum inhibitory concentrations for meropenem than imipenem. All of the IMP-6-producing isolates had class 1 integrons with amplification sizes of 4.5 kb/5.5 kb (34 isolates) or 3.0 kb (1 isolate); 4.5 kb/5.5 kb integrons had bla(IMP-6)-qac-aacA4-bla(OXA-1)-aadA1 (5.5 kb) and aadB-cmlA-bla(OXA-10)-aadA1 (4.5 kb). Pulsed-field gel electrophoresis (PFGE) analysis indicated that all IMP-6-producing P. aeruginosa from various geographic areas had nearly identical patterns with >85% similarity. All IMP-6-producing isolates showed high genetic similarity to those obtained from tertiary care hospitals and had the same integron type, indicating the spread of these strains to the three types of hospitals nationwide. These data show the wide spreading of clonally related IMP-6-producing P. aeruginosa (sequence type 235) through tertiary, non-tertiary and geriatric hospitals in South Korea. Continuous monitoring and thorough infection control should be performed in all types of hospitals to prevent further spreading of MBL-producing P. aeruginosa.     

北京市2016—2017年耐碳青霉烯类肺炎克雷伯菌分子流行病学和遗传特征调查

目的 调查北京市2016—2017年耐碳青霉烯类肺炎克雷伯菌中碳青霉烯酶基因流行现状和遗传背景。方法 挑选2016—2017年北京市细菌耐药监测项目收集的厄他培南耐药肺炎克雷伯菌为碳青霉烯类耐药肺炎克雷伯菌(carbapenem-resistant Klebsiella pneumoniae, CRKP)。PCR扩增检测CRKP中碳青霉烯酶基因(blaKPC、blaSME、blaIMI、blaGES、blaIMP、blaVIM、blaSPM、blaSIM、blaGIM、blaNDM和blaOXA-48)；mCIM和eCIM法检测碳青霉烯酶。脉冲场凝胶电泳和多位点序列分析检测不同菌株的同源性。采用美国临床实验室标准协会(CLSI)推荐的琼脂二倍稀释法检测常见抗菌药物对其最低抑菌浓度(MIC)。采用S1-PFGE和Southern Blotting技术进行blaKPC-2和blaNDM-5基因定位。采用接合实验检测blaKPC-2和blaNDM-5基因的水平传递性。三代测序技术分析blaNDM-5基因遗传背景。结果 2016—2017年北京14家二级和三级医院收集的肺炎克雷伯菌中共筛选出78株CRKP，其中64株检出blaKPC-2基因，1株检出blaNDM-1基因，1株检出blaNDM-5基因，检出率分别为82.1%、1.3%和1.3%。mCIM和eCIM检测的敏感度和特异度均为100%。MLST将66株碳青霉烯酶基因阳性菌分为12个不同的ST型，其中以ST11为主，共46株(69.7%)。PFGE结果显示共有52个PFGE型别。所有碳青霉烯酶基因阳性菌均对碳青霉烯类抗生素耐药，对其他常见抗菌药物如β-内酰胺类合剂、第三/四代头孢菌素、单环β-内酰胺类、喹诺酮类抗菌药物的耐药率大于87%。对携带blaKPC-2和blaNDM-5基因的CRKP进行基因定位分析发现，仅一株菌所携带blaKPC-2基因定位在染色体上，其他均定位在质粒上，有4株细菌接合成功，其中携带blaNDM-5基因的是一个大小约为46kb的质粒，质粒类型为IncX3型。遗传背景分析blaNDM-5基因上游为Tn3、IS3000、ISAba125和IS5，下游为bleMBL、trpF、dsbC和IS26。结论 北京地区耐碳青霉烯类肺炎克雷伯菌分子型别多态性大，同时又存在优势序列型，为ST11型。携带blaKPC-2基因的质粒大小不一，提示其遗传背景可能比较复杂。与blaKPC-2基因不同，对比国内外其他研究发现blaNDM-5基因的遗传背景比较稳定，IncX3型质粒在介导blaNDM-5基因的传播上发挥着重要作用。     

北京市2016—2017年耐碳青霉烯类肺炎克雷伯菌分子流行病学和遗传特征调查

目的 调查北京市2016—2017年耐碳青霉烯类肺炎克雷伯菌中碳青霉烯酶基因流行现状和遗传背景。方法 挑选2016—2017年北京市细菌耐药监测项目收集的厄他培南耐药肺炎克雷伯菌为碳青霉烯类耐药肺炎克雷伯菌(carbapenem-resistant Klebsiella pneumoniae, CRKP)。PCR扩增检测CRKP中碳青霉烯酶基因(blaKPC、blaSME、blaIMI、blaGES、blaIMP、blaVIM、blaSPM、blaSIM、blaGIM、blaNDM和blaOXA-48);mCIM和eCIM法检测碳青霉烯酶。脉冲场凝胶电泳和多位点序列分析检测不同菌株的同源性。采用美国临床实验室标准协会(CLSI)推荐的琼脂二倍稀释法检测常见抗菌药物对其最低抑菌浓度(MIC)。采用S1-PFGE和Southern Blotting技术进行blaKPC-2和blaNDM-5基因定位。采用接合实验检测blaKPC-2和blaNDM-5基因的水平传递性。三代测序技术分析blaNDM-5基因遗传背景。结果 2016—2017年北京14家二级和三级医院收集的肺炎克雷伯菌中共筛选出78株CRKP,其中64株检出blaKPC-2基因,1株检出blaNDM-1基因,1株检出blaNDM-5基因,检出率分别为82.1%、1.3%和1.3%。mCIM和eCIM检测的敏感度和特异度均为100%。MLST将66株碳青霉烯酶基因阳性菌分为12个不同的ST型,其中以ST11为主,共46株(69.7%)。PFGE结果显示共有52个PFGE型别。所有碳青霉烯酶基因阳性菌均对碳青霉烯类抗生素耐药,对其他常见抗菌药物如β-内酰胺类合剂、第三/四代头孢菌素、单环β-内酰胺类、喹诺酮类抗菌药物的耐药率大于87%。对携带blaKPC-2和blaNDM-5基因的CRKP进行基因定位分析发现,仅一株菌所携带blaKPC-2基因定位在染色体上,其他均定位在质粒上,有4株细菌接合成功,其中携带blaNDM-5基因的是一个大小约为46kb的质粒,质粒类型为IncX3型。遗传背景分析blaNDM-5基因上游为Tn3、IS3000、ISAba125和IS5,下游为bleMBL、trpF、dsbC和IS26。结论     

Dissemination and spread of CTX-M extended-spectrum beta-lactamases among clinical isolates of Klebsiella pneumoniae in central China

Of 50 extended-spectrum beta-lactamase-producing (ESBL) isolates of Klebsiella pneumoniae collected from six hospitals in Hubei Province, 20 were found to produce CTX-M ESBLs (40%). Sequence analysis of the six isolates carrying bla(CTX-M) genes revealed that they all harboured bla(CTX-M-3). In the majority of isolates, bla(CTX-M) genes were within large conjugative plasmids. A high degree of diversity of the RAPD types revealed that all the isolates carrying CTX-M were genetically unrelated and horizontal transfer of plasmids was probably the main mechanism of bla(CTX-M) spread. This is the first report of the occurrence of CTX-M-3 ESBLs in central China; previously this enzyme was identified only in Europe. A more comprehensive survey of ESBL types from China is urgently needed.     

Trends in antimicrobial drug resistance in Salmonella enterica serotypes Typhi and Paratyphi A isolated in Europe, 1999-2001

Results of antimicrobial sensitivity tests for strains of Salmonella enterica serotypes Typhi and Paratyphi A isolated from patients in ten European countries between 1999 and 2001 have been transferred electronically to the Enter-net surveillance hub. For Typhi between 22 and 29% of isolates were multiresistant (to four drugs or more) with decreased susceptibility to ciprofloxacin (MIC 0.25-1.0 mg/l) increasing from 20% in 1999 to 26% in 2001. Nineteen of 169 (11%) strains with decreased ciprofloxacin susceptibility were sensitive to nalidixic acid. For Paratyphi A multiple resistance increased from 9% in 1999 to 25% in 2001 and decreased ciprofloxacin susceptibility from 6 to 17%. Clinicians should be aware of the possibility of treatment failures when fluoroquinolones are used as the first-line drug for infections with Typhi and Paratyphi A, particularly for patients recently returning from areas where drug-resistant strains are endemic.     

Multiple transmissible genes encoding fluoroquinolone and third-generation cephalosporin resistance co-located in non-typhoidal Salmonella isolated from food-producing animals in China

The aim of this study was to identify genes conferring resistance to fluoroquinolones and extended-spectrum β-lactams in non-typhoidal Salmonella (NTS) from food-producing animals in China. In total, 31 non-duplicate NTS were obtained from food-producing animals that were sick. Isolates were identified and serotyped and the genetic relatedness of the isolates was determined by pulsed-field gel electrophoresis of XbaI-digested chromosomal DNA. Antimicrobial susceptibility was determined using Clinical and Laboratory Standards Institute methodology. The presence of extended-spectrum β-lactamase (ESBL) and fluoroquinolone resistance genes was established by PCR and sequencing. Genes encoded on transmissible elements were identified by conjugation and transformation. Plasmids were typed by PCR-based replicon typing. The occurrence and diversity of numerous different transmissible genes conferring fluoroquinolone resistance [qnrA, qnrD, oqxA and aac(6′)-Ib-cr] and ESBLs (CTX-M-27 and CTX-M-14), and which co-resided in different isolates and serovars of Salmonella, were much higher than in European countries. Furthermore, different plasmids encoded fluoroquinolone resistance (ca. 6 kb) and β-lactam resistance (ca. 63 kb) and these co-resided in isolates with mutations in topoisomerase genes (gyrA and parC) giving very resistant Salmonella. The presence of multidrug-resistant bacteria in food-producing animals in countries that export foodstuffs suggests that global transfer of antibiotic resistances from country to country on food is possible.     

Epidemiology of SHV-type beta-lactamase-producing Klebsiella spp. from outbreaks in five geographically distant Hungarian neonatal intensive care units: widespread dissemination of epidemic R-plasmids

One hundred and twenty-six extended-spectrum β-lactamase-producing clinical isolates of Klebsiella spp. were collected in 1998, 2002 and 2003 from seven outbreaks in neonatal intensive care units (NICUs) of five Hungarian county and teaching hospitals. The isolates were multidrug resistant but were susceptible to ciprofloxacin. Pulsed-field gel electrophoresis revealed the existence of 12 distinct genetic clones, 10 of which proved epidemic in the studied NICUs. All isolates harboured plasmids ranging from 2.3 kb to 228 kb, representing 12 diverse plasmid profiles. Sequence analysis of SHV-specific polymerase chain reaction products from 13 representative isolates detected the bla_SHV-2a gene in three and the bla_SHV-5 gene in seven epidemic clones, respectively. In the majority of isolates the bla_SHV genes were on transferable plasmids of 94 kb. EcoRI and PstI digestion of plasmid DNA from transconjugants revealed identical or closely related restriction patterns in nine bla_SHV-5-harbouring R-plasmids and in two bla_SHV-2a-harbouring R-plasmids carried by strains obtained from geographically distant NICUs. Endemic clones in individual wards or epidemic clones affecting multiple healthcare facilities were not found. However, similarities observed in the size and restriction pattern of the plasmids hints at the multiple transfer of epidemic R-plasmids responsible for a sequence of outbreaks in Hungary.     

Detection of an integrated tetracycline-resistance plasmid in Staphylococcus aureus from a Nigerian hospital

The genetics of tetracycline-resistance determinants was studied in eight methicillin-resistant and two methicillin-sensitive Staphylococcus aureus isolated from a Nigerian hospital. Curing and transfer experiments demonstrated that one methicillin-sensitive S. aureus isolate WBG4762, had a 4.4 kb extrachromosomal plasmid- as well as a chromosomally-mediated tetracycline resistance. All others had chromosomal tetracycline resistance and were resistant to either tetracycline and minocycline or tetracycline only. The two methicillin-susceptible isolates were resistant to both tetracycline and minocycline. Chromosomal DNA from all the resistant isolates hybridized with a digoxigenin-11-dUTP labeled 4.4 kb tetracycline-resistance plasmid probe indicating that they contained tetracycline-resistance plasmids similar to the probe integrated into their chromosomes. The results demonstrated the presence of integrated tetracycline-resistance plasmid in both methicillin-resistant and methicillin-susceptible S. aureus resistant to tetracycline and minocycline as well as those resistant only to tetracycline. This is the first demonstration of an integrated tetracycline-resistance plasmid in methicillin-sensitive S. aureus and suggests that the integrated tetracycline-resistance plasmid may be widespread in S. aureus.     

Identification of Plasmid Containing Bacteria in an Activated Sludge Reactor

Samples taken from an activated sludge reactor used for the biodegradation of metal cutting fluids were studied for the presence of plasmid-containing bacteria. Twenty different bacterial isolates contained one or more plasmids. After numerous transfers of the isolates through LB broth, 55% of the plasmids were spontaneously lost as evidenced by agarose gel electrophoresis. Eighty percent of the isolates were resistant to one or more antibiotics, 65% resistant to two or more antibiotics, 40% resistant to three or more, 20% resistant to four or more and 5% resistant to five antibiotics. The isolates were also tested for their sensitivity to several common metals. This study has demonstrated that activated sludge is a natural reservoir for plasmid-containing bacteria involved in biodegradation of wastes.     

Antimicrobial susceptibility of Pseudomonas aeruginosa isolated at Kochi Municipal Central Hospital in the last 3 years

Antimicrobial susceptibility of Pseudomonas aeruginosa isolated at Kochi Municipal Central Hospital between 2001 and 2003 was assessed according to the NCCLS interpretive criteria. 1. The piperacillin-susceptible rate was 92.9%. 2. Among cephem antibiotics, the ceftazidime-susceptible rate was the highest (96.0%). 3. As for aminoglycosides, susceptibility to tobramycin and amikacin remained with a susceptible rate of 93.2% and 94.8%, respectively. 4. The carbapenem-susceptibility remained high. The susceptible rate for meropenem (94.1%) was higher than that for imipenem (88.3%). 5. Acquisition of resistance was observed in urinary isolates. Four multi-drug resistant P. aeruginosa, which are resistant to all of imipenem, amikacin and ofloxacin were isolated in this study and all were isolated from urine. 6. Of 388 isolates, 34 isolates were resistant to imipenem, but no positive isolate was found in screening of metallo-beta-lactamase-producing bacteria.     

耐药鲍曼不动杆菌不同年份分离株耐药元件基因比较研究

目的 调查两组相隔7年的鲍曼不动杆菌菌株可能存在的耐药基因状况及菌株间的亲缘关系。方法 分别收集南京医科大学附属淮安第一医院2008年20株鲍曼不动杆菌，2016年20株鲍曼不动杆菌。菌种鉴定为鲍曼不动杆菌种特异mdfA基因与blaOXA-51基因PCR双重检测为阳性方确认为鲍曼不动杆菌。再用PCR方法检测32种β-内酰胺类药物获得性耐药基因、15种氨基糖苷类药物获得性耐药基因、10种可移动遗传元件遗传标记，最后对检测结果作样本聚类分析(UPGMA法)。 结果 2016年分离株对第三代头孢类药物、碳青霉烯类药物、氨基糖苷类药物、喹诺酮药物均为耐药。2008年分离株仅对第三代头孢类药物均为耐药，而对碳青霉烯类药物均为敏感，对喹诺酮药物、氨基糖苷类药物分别有50.00%和60.00%的敏感性。2008和2016年分离株均检出blaADC和blaOXA-51，但blaOXA-2群、blaOXA-23群只有2016年分离株均被检出。2008年分离株对第三代头孢类药物耐药主要与blaADC相关，2016年分离株对第三代头孢类药物、碳青霉烯类药物耐药主要与blaADC、blaOXA-2群和blaOXA-23群相关。2016年分离株均测出aac(2)-Ⅰb、aph(3)-Ⅰ、armA等3种氨基糖苷类药物耐药相关基因，而2008年分离株均无检出。可移动遗传元件遗传标记tnpU、tnp513、IS26和ISaba1等4种也只有2016年分离株被全部检出。菌株亲缘关系分析可见2008和2016年不同年份分离株分成两个独立的簇群(A簇群和B簇群)，2016年分离株聚集性更强相差系数更小。A和B簇群均可分为两个亚簇群。A-1亚簇群有两个克隆播散，A-2、B-1和B2亚簇群各有一个克隆播散。其中2016年分离株B-簇群一个有14株菌构成的大克隆播散。分离株耐药元件检测阳性模式显示，2008年分离株仅携带2~7种耐药元件基因；2016年分离株则携带14种~16种耐药元件基因。结论 多种β-内酰胺类药物耐药基因、氨基糖苷类药物耐药基因和可移动遗传元件是导致鲍曼不动杆菌对抗菌药物耐药的重要原因。在同一家医院的对相隔7年的鲍曼不动杆菌临床分离株进行耐药元件基因检测与分析是国内首次报道。不同年份分离株的耐药性和耐药元件基因携带状况差异明显：2016年分离株比2008年分离株耐药性更强，携带的耐药元件基因更多。2008年和2016年分离株均有克隆播散，提示有医院感染的存在。     

Detection of novel gyrA mutations in nalidixic acid-resistant isolates of Salmonella enterica from patients with diarrhoea

The aim of the current study was to detect mutations in the gyrA gene of quinolone-resistant Salmonella spp. isolates recovered in Tehran, Iran. Between April 2008 and September 2009, 174 Salmonella spp. were collected and assayed for quinolone resistance and detection of gyrA mutations. Isolates identified as Salmonella enterica were tested for susceptibility by the disk diffusion method. Polymerase chain reaction (PCR) amplification and sequencing of the gyrA gene segment encoding the quinolone resistance-determining region (QRDR) were performed for the nalidixic acid-resistant isolates. Amongst the 174 recovered Salmonella spp. isolates, 89 were resistant to nalidixic acid, of which 9 were resistant to enrofloxacin; 10 isolates had reduced susceptibility to nalidixic acid. None of the isolates were resistant to ciprofloxacin, but a single isolate showed reduced susceptibility. Twelve types of amino acid replacement were found in the QRDR region of GyrA, namely the previously described substitutions in positions 83 and 87 as well as five new substitutions Leu41-Pro, Arg47-Ser, Ser111-Thr, Ala118-Thr and Asp147-Gly. Double substitutions in both positions 83 and 87 were not identified. A Gly133-Glu substitution was identified in a single S. enterica serotype Typhi isolate.     

儿童与成人常见病原菌耐药性比较

目的：比较儿童与成人常见病原菌耐药状况。方法：监测2010年度泉州市儿童医院与泉州市第一医院临床分离细菌的耐药状况,以WHONET5.5软件进行数据分析,比较儿童与成人临床常见病原菌的耐药性差异。结果：由儿童患者分离得到致病菌1815株,其中革兰阳性菌767株（占42.3%）,革兰阴性菌1048株（占57.7%）;最常见的细菌依次为肺炎克雷伯菌、大肠埃希菌、金黄色葡萄球菌、流感嗜血杆菌、铜绿假单胞菌、鲍曼不动杆菌。由成人患者分离得到致病菌2345株,其中革兰阳性菌768株（占32.8%）,革兰阴性菌1577株（占67.2%）;最常见的细菌依次为大肠埃希菌、鲍曼不动杆菌、肺炎克雷伯菌、金黄色葡萄球菌、肠球菌、铜绿假单胞菌。儿童和成人耐甲氧西林金黄色葡萄球菌（MRSA）的检出率分别为19.8%和17.8%;儿童患者大肠埃希菌和肺炎克雷伯菌对阿米卡星和喹诺酮类药的耐药率要远低于成人;儿童患者铜绿假单胞菌和鲍曼不动杆菌对抗菌药物的耐药率低于成人,特别是对氨基糖苷类和喹诺酮类药。结论：儿童患者常见病原菌分布和耐药特点与成人存在一定的差异;应持续地进行细菌耐药监测。