Antimicrobial drug resistance in nontyphoid human Salmonella in Belgium: trends for the period 2000-2002

In order to assess antimicrobial resistance in nontyphoid human Salmonella in Belgium, the six most important serovars, representing together more than 90% of laboratory confirmed cases, were randomly sampled. From June 2000 until December 2002, a total of 1756 isolates were screened for their antimicrobial resistance profile by the disc diffusion method. S. Hadar strains showed the highest level of antimicrobial resistance. Simultaneous resistance to ampicillin, nalidixic acid, tetracycline and streptomycin was observed in 81.5, 58 and 76.1% of these isolates in 2000, 2001 and 2002, respectively. All S. Hadar isolates resistant to nalidixic acid also displayed decreased susceptibility to ciprofloxacin (MIC50 values of 0.25 microg/mL in 2000-2001 and 0.19 microg/mL in 2002). In 2000, 2001 and 2002, respectively 44.6, 46 and 36.5% of S. Typhimurium isolates were multiresistant (resistant to 4 or more antimicrobial agents). These multiresistant isolates were preferably associated with a few phage types, such as DT104. Complete resistance to ciprofloxacin was detected in three S. Typhimurium isolates and sequencing of the gyrA gene revealed for each isolate two mutations at codons corresponding to Ser-83 and Asp-87. Multiresistance was also common in S. Virchow (7.7%, 15.9% and 29.7%, in 2000, 2001 and 2002, respectively). Resistance to nalidixic acid in S. Virchow isolates increased from 46.2% in 2000 to 80.9% in 2002 and six S. Virchow isolates were detected as cefotaxime resistant. In contrast, the vast majority of S. Enteritidis, S. Brandenburg and S. Derby isolates remained sensitive to almost all antimicrobial agents tested.     

Imported Enteric Fever: Case Series from the Hospital for Tropical Diseases,London, United Kingdom

Our current knowledge of the clinical characteristics of enteric fever is drawn mainly from population-based studies in disease-endemic countries, and there are limited data published on cases in returning travelers. We report the clinical characteristics of enteric fever in 92 travelers returning to London, United Kingdom. Salmonella typhi and S. paratyphi resulted in an almost indistinguishable clinical picture. Rose spots and relative bradycardia were found only in a few patients. A total of 91% of the patients had a normal leukocyte count, which was associated with a markedly increased level of alanine aminotransferase in 82%. A total of 57% of the S. typhi isolates had decreased susceptibility to ciprofloxacin and resistance to nalidixic acid; these isolates were from southern Asia. Thirty percent were multidrug resistant; all were from southern Asia and Nigeria. None of the paratyphoid isolates were multidrug resistant but rates of decreased susceptibility to fluoroquinolones were higher than in S. typhi (74%).     

Rapid sequence-based identification of gonococcal transmission clusters in a large metropolitan area

In large metropolitan areas, which typically have the highest rates of gonorrhea, the identification of chains of transmission by use of partner notification is problematic, and there is an increasing interest in applying molecular approaches, which would require new discriminatory high-throughput procedures for recognizing clusters of indistinguishable gonococci, procedures that identify local chains of transmission. Sequencing of internal fragments of 2 highly polymorphic loci, from 436 isolates recovered in London during a 3-month period, identified clusters of antibiotic-resistant and antibiotic-susceptible isolates with indistinguishable genotypes, the vast majority of which were also identical or closely related by other methods, and defined groups of individuals who typically had similar demographic characteristics. This discriminatory sequence-based approach produces unambiguous data that easily can be compared via the Internet and appears to be suitable for the identification of linked cases of gonorrhea and the timely identification of transmission of antibiotic-resistant strains, even within large cities.     

What is new with antibiotic-resistant gonorrhoea in Newcastle,England?

Neisseria gonorrhoeae isolates that were resistant to ciprofloxacin and/or penicillin were analysed to investigate the escalating problem of antibiotic-resistant gonorrhoea in the north east of England. Opa-typing (outer membrane opacity protein) was carried out on isolates resistant to ciprofloxacin and of nutrient nonrequiring (NR) auxotype. In the year 2000 there were 265 cases of gonorrhoea, of which 44 (16.6%) were resistant to penicillin and 12 (4.5%) were resistant or had reduced sensitivity to ciprofloxacin (with only four of these acquired outside the UK). Three (7.5%) of the non-beta-lactamase penicillin-resistant isolates were imported from abroad. By Opa-typing of ciprofloxacin-resistant strains, one pair of the isolates was similar, two were unique and one was similar to the Oldham/Rochdale outbreak strain described early in 2000. This marked increase in the prevalence of indigenous ciprofloxacin resistance requires continued surveillance and may soon necessitate an alteration in our first line treatment.     

A disseminated multidrug-resistant clonal group of uropathogenic Escherichia coli in pyelonephritis

In acute pyelonephritis, bacterial resistance to co-trimoxazole predicts treatment failure, but the clonal basis of such resistance is undefined. We did molecular and serological analyses of 170 Escherichia coli urine isolates obtained in 1994-96 from women with acute pyelonephritis. 12 (7%) of the pyelonephritis isolates were in clonal group A (CGA; responsible for 38-51% of co-trimoxazole resistance in acute cystitis), including ten (34%) of 29 isolates that were resistant to co-trimoxazole. CGA isolates were obtained from diverse locations across the USA and were related to the O15:K52:H1 clone of the 1986-87 outbreak in London, UK. Thus, CGA is broadly disseminated and contributes to co-trimoxazole resistance in pyelonephritis as well as in cystitis.     

Neisseria gonorrhoeae in a London sexually transmitted infection clinic not fully sensitive to quinolones: are isolates imported and how effective is ciprofloxacin as a first-line therapy?

Our objectives were to determine the prevalence of Neisseria gonorrhoeae not fully sensitive to ciprofloxacin from a sexually transmitted infection (STI) clinic in London and where the isolates were acquired from. Data of antibiotic sensitivities of N. gonorrhoeae from 292 patients were reviewed over a 6-month period at St Mary's Genitourinary Medicine (GUM) Clinic, London. Isolates which exhibited reduced susceptibility (minimum inhibitory concentration [MIC] 0.03-0.12 mg/l) and high level resistance (MIC>0.12 mg/l) to ciprofloxacin represented 10% and 1.3% of the total respectively. All patients infected with a high level resistant isolate to ciprofloxacin had had a recent sexual partner from abroad but 18 of the 28 patients infected with a reduced susceptibility isolate denied recent travel. None of the 20 patients with a non-sensitive isolate who re-attended for post treatment cultures had persistant gonococcal infection. From this study we concluded that although N. gonorrhoeae resistant to ciprofloxacin was rare and probably always acquired abroad, isolates exhibiting reduced susceptibility were more common and were mainly as a result of infection from the UK. A stat dose of ciprofloxacin 500 mg and doxycycline 100 mg twice a day for one week was effective treatment.     

Antimicrobial drug resistance in isolates of Salmonella enterica from cases of salmonellosis in humans in Europe in 2000: results of international multi-centre surveillance

The Enter-net surveillance system received results of antimicrobial sensitivity tests for isolates from over 27 000 cases of human salmonellosis in 2000 in 10 European countries. Almost 40% of isolates were resistant to at least one antimicrobial, with 18% multiresistant. Resistance to ampicillin, streptomycin, sulphonamides and tetracyclines was common, with over 20% of isolates resistant to at least one of these antimicrobials. Clinical resistance to ciprofloxacin was rare, with only 0.5% of isolates exhibiting such resistance (MIC >1.0 mg/l). Resistance to nalidixic acid coupled with a decreased susceptibility to ciprofloxacin (MIC 0.25-1.0 mg/l) was more common, with 14% of isolates showing these properties. Resistance to third-generation cephalosporins was rare with only 0.6% of isolates resistant to cefotaxime. In all countries multiple resistance was most common in Salmonella enterica serotype Typhimurium, with 51% of isolates multiresistant in total. In England and Wales multiple resistance was also prevalent in S. Virchow and S. Hadar, whereas in other countries multiple resistance was common in serotypes such as S. Blockley.     

IS6110-RFLP and spoligotyping of Mycobacterium tuberculosis isolates in Iran

To evaluate and compare the usefulness of IS6110-restriction fragment length polymorphism (RFLP) and spoligotyping in the epidemiology of tuberculosis in Iran, Mycobacterium tuberculosis complex strains, isolated in 2 different areas of Iran, were subjected to RFLP and spoligotyping. The average number of IS6110 copies per strain was 11 and ranged from 5 to 18 among the M. tuberculosis strains. In total, among the 62 isolates, 56 different patterns were observed. 50 strains had unique RFLP patterns (89%) and 12 (11%) revealed patterns that were found among at least 1 other isolate. Spoligotyping of 97 isolates resulted in 42 different patterns, of which 72% were found in 15 clusters. 14 (29%) out of 48 investigated isolates were resistant to 1 or more antituberculosis drugs and 57% of the resistant isolates were isolated from Afghan immigrants. Ten percent of the isolates represented the Beijing genotype, including 4 of the 14 (36%) resistant strains. Three of these resistant Beijing strains were isolated from Afghan patients. IS6110-RFLP typing could be useful for studying the epidemiology of tuberculosis in Iran. IS6110 patterns were polymorphic and the average IS6110 copy number was high.     

Antibiotic-resistant flora in nursing home patients admitted to the hospital

To study carriage of multiply resistant gram-negative bacilli, 50 patients admitted to the hospital from nursing homes (NHs) and 50 control admissions not from NHs were matched for age and recent antibiotic use. Their antibiotic resistance patterns were similar: 20 NH patients and 14 controls had resistant strains. However, significantly more patients (64%) from NHs with large numbers of "skilled beds" had resistant bacteria than did patients from small NHs (21%) or controls (28%). Also, more patients from NHs had members of the Proteus-Providencia-Morganella group in their urine than did controls. Discriminant analysis showed that residence in NHs with large numbers of skilled beds, recent antibiotic use, and bladder dysfunction (indwelling catheter or incontinence) were independently important in predicting carriage of resistant strains in NH and control patients. Over 75% of resistant isolates were from rectal specimens, emphasizing the occult way that such strains are brought into the hospital.     

Epidemiological analysis of Salmonella enterica serotype typhimurium from Hong Kong by ribotyping and pulsed-field gel electrophoresis

We investigated the antimicrobial susceptibilities and molecular epidemiology of 200 strains of Salmonella enterica serotype typhimurium isolated from 1989 to 1996 in Hong Kong. Only 22% of strains were susceptible to all 19 antibiotics tested but all were susceptible to second- and third-generation cephalosporins. Up to 9% of strains were resistant to 0.12 mg/l concentrations of ciprofloxacin or ofloxacin but none were resistant to 1 or 2 mg/l concentrations of these 2 drugs, respectively. The isolates were grouped into 15 types by ribotyping with restriction endonuclease EcoRI and into 53 types by pulsed-field gel electrophoresis of XbaI-restricted DNA fragments. When DNA fragments of the ribotypes and pulsotypes were pooled and analyzed 87 types resulted, 76 (87%) of which were of > 90% similarity and were grouped into 15 clusters. About 60% of the isolates belonged to 3 clusters, which probably represented 3 clones endemic in the community. The rest of the isolates were of a large variety of types or clusters. For epidemiological purposes analysis of pooled results from different molecular techniques would be more discriminative than results from individual techniques alone.     

ESBL genotypes in fluoroquinolone-resistant and fluoroquinolone-susceptible ESBL-producing Escherichia coli urinary isolates in Manitoba

OBJECTIVE: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are increasingly common in nosocomial and community settings. Furthermore, fluoroquinolone (FQ) and even multidrug resistance (MDR) appear to be associated with certain ESBL genotypes. The purpose of the present study was to determine which ESBL genotypes are associated with FQ and MDR in E coli urinary isolates in Manitoba. METHODS: The authors determined the antimicrobial susceptibility, genetic similarity and ESBL genotype of 27 FQ-resistant and seven FQ-susceptible, ESBL-producing urinary isolates submitted to the clinical microbiology laboratories of two teaching hospitals between October 2000 and April 2005. Susceptibilities to beta-lactams, FQs, trimethoprim-sulfamethoxazole (SXT), doxycycline (DOX), gentamicin (GM) and tigecycline were determined by microbroth dilution; pulsed-field gel electrophoresis (PFGE) was used to determine genetic relatedness, and ESBL genotype was determined by polymerase chain reaction and sequencing. RESULTS: Of 34 ESBL-producing organisms, 27 (79.4%) were found to be ciprofloxacin (CIP) resistant, 27 (79.4%) were SXT resistant, eight (23.5%) were GM resistant and 29 (85.3%) were DOX resistant. Twenty-three (67.6%) had MDR, with concomitant resistance to CIP and SXT; 16 had concomitant resistance to CIP, SXT and DOX; and seven (20.6%) had MDR, with concomitant resistance to CIP, SXT, DOX and GM. All isolates were susceptible to tigecycline. Of 27 FQ-resistant ESBL-producing organisms, seven (25.9%) were genotype CTX-M-14, 19 (70.4%) were genotype CTX-M-15 and one (3.7%) was genotype CTX-M-24. Among the seven FQ-susceptible strains, three (42.8%) expressed SHV-type enzymes, three (42.8%) expressed TEM-type enzymes and one (14.3%) expressed CTX-M-9. CTX-M-15 was the most common MDR-associated genotype. Of a total of 19 strains, 18 (94.7%) were resistant to FQs and SXT; 15 (78.9%) were resistant to FQs, SXT and DOX; and five (26.3%) were resistant to FQs, SXT, DOX and GM. PFGE analysis revealed genetic similarity within CTX-M-15-producing isolates only. CONCLUSION: CTX-M-15 in E coli is strongly associated with an MDR phenotype compared with other genotypes. CTX-M-14 is associated with FQ resistance only. PFGE suggests clonality of CTX-M-15-producing isolates within and among hospitals.     

Frequency of embB codon 306 mutations in ethambutol-susceptible and -resistant clinical Mycobacterium tuberculosis isolates in Kuwait

SETTING: Recent reports of embB306 mutations in ethambutol-resistant and ethambutol-susceptible drug-resistant strains of Mycobacterium tuberculosis have questioned the significance of these mutations in conferring resistance to ethambutol (EMB). OBJECTIVE: To determine the occurrence of embB306 mutations in all EMB-resistant and -susceptible drug-resistant M. tuberculosis strains isolated during a specified period at a single geographical location. DESIGN: Twenty-five pansusceptible, all EMB-resistant and -susceptible M. tuberculosis strains resistant to other first-line drugs isolated in Kuwait during 2000-2003 were analyzed. The embB306 mutations were detected by PCR-restriction fragment length polymorphism and DNA sequencing. The PCR-based methods were also used for determining strain relatedness. RESULTS: None of the pansusceptible M. tuberculosis strains contained a mutation at embB306. Fifteen of 50 (30%) EMB-resistant strains but only three of 122 (2%) EMB-susceptible isolates resistant to other first-line drugs contained a mutated embB306. The EMB-susceptible isolates with embB306 mutation were resistant to isoniazid plus other drug(s). The isolates carrying similar mutations were genotypically distinct strains. CONCLUSIONS: The frequency of embB306 mutations in EMB-resistant strains compared to EMB-susceptible M. tuberculosis isolates resistant to other drugs was 15 times higher. Association of embB306 mutations in EMB-susceptible strains with isoniazid resistance and inherent problems associated with phenotypic EMB susceptibility testing suggest that these strains may actually be EMB-resistant.     

Postvaccine genetic structure of Streptococcus pneumoniae serotype 19A from children in the United States

BACKGROUND: The introduction of the 7-valent conjugate pneumococcal vaccine (PCV7) in children may result in serotype replacement. We estimated the rate of increase of invasive pneumococcal disease (IPD) caused by serotype 19A in children <5 years old and determined the genetic composition of these isolates. METHODS: Cases of IPD between July 1999 and June 2004 were identified through the Active Bacterial Core Surveillance. Serotype 19A isolates obtained from children <5 years old between January 2003 and June 2004 were characterized by serotyping, antibiotic susceptibility testing, and pulsed-field gel electrophoresis (PFGE). Select isolates representing homologous PFGE clusters were subjected to multilocus sequence typing, and eBURST was used to delineate clonal groups. RESULTS: Between July 1999 and June 2004, the overall rate of IPD decreased from 23.3 to 13.1 cases/100,000 population (P<.00001). In children <5 years old, the rate decreased from 88.7 to 22.4 cases/100,000 population (P<.00001), whereas the rate in persons > or =5 years old decreased from 18.4 to 12.4 cases/100,000 population (P<.0001). The rate of serotype 19A IPD in children <5 years old increased significantly from 2.6 cases/100,000 population in 1999-2000 to 6.5 cases/100,000 population in 2003-2004; this was accompanied by significant increases in penicillin nonsusceptibility (P=.008) and multidrug resistance (P=.002) among serotype 19A isolates. As was observed during the pre-PCV7 era, clonal complex (CC) 199 predominated within serotype 19A, representing approximately 70% of invasive serotype 19A isolates from children <5 years old during 2003-2004. New serotype 19A genotypes were observed during 2003-2004, including 6 CCs that were not found among pneumococcal serotype 19A isolates during surveillance in 1999. CONCLUSION: Serotype 19A is, at present, the most important cause of IPD by replacement serotypes, and it is increasingly drug resistant. CC199 is the predominant CC among type 19A serotypes in children <5 years old. Our data suggest that some of the increase in rates of infection with serotype 19A may be due to serotype switching within certain vaccine type strains.     

Surveillance of Mycobacterium tuberculosis drug resistance in Hong Kong, 1986-1999, after the implementation of directly observed treatment.

OBJECTIVE: To study changing trends in TB epidemiology with emphasis on drug resistance rates in various age groups from 1986-1999. DESIGN: Laboratory-based data on drug susceptibility testing against streptomycin (SM), isoniazid (NH), rifampicin (RMP) and ethambutol (EMB) had been collected continuously in a centralised TB laboratory in Hong Kong. Epidemiological parameters such as sex, age and drug resistance rates in new and retreatment cases were measured and analysed for longitudinal trends. RESULTS: Of 48 924 non-duplicate isolates from new TB cases, 7045 (14.4%) were resistant to one or more drugs, 5773 (11.8%) were resistant to SM and/or INH while 881 (1.8%) were multidrug-resistant (MDR-TB). Of 3857 isolates from retreatment patients, 1176 (30.5%) were resistant to one or more drugs, 616 (16.0%) were resistant to SM and/or [NH, and 467 (12.1%) were MDR-TB. For isolates from new cases, significant declines were observed in the resistance rates against any drug, SM alone, INH alone, SM+INH and INH+RMP. For retreatment isolates, significant declines were also observed in resistance to any drug and INH+RMP. In both new and retreatment cases, isolates from patients aged over 65 years showed significantly lower drug resistance (any drug and INH+RMP) compared with other age groups (16-34 years and 35-65 years). CONCLUSION: With successful implementation of DOTS over a 14-year period, laboratory-based surveillance data showed significant declines in drug resistance, including MDR-TB. This has occurred amidst demographic changes associated with a generally ageing population as well as highly mobile sectors that are in constant exchange with highly endemic areas.     

Antibiotic resistance, plasmid profile and RAPD-PCR analysis of enteropathogenic Escherichia coli (EPEC) clinical isolates

Enteropathogenic Escherichia coli (EPEC) is a leading cause of diarrhea among infants in developing countries. A total of 38 EPEC isolates, obtained from diarrhea patients of Hospital Miri, Sarawak, were investigated through plasmid profile, antibiotic resistance and randomly amplified polymorphic DNA (RAPD) analysis. From the 8 types of antibiotics used, all isolates were 100% resistant to furoxime, cephalothin and sulphamethoxazole and showed high multiple antibiotic resistant (MAR) indexes, ranging from 0.5 to 1.0. In plasmid profiling, 22 isolates (58%) showed the presence of one or more plasmids in the range 1.0 to 30.9 mDa. The dendrogram obtained from the results of the RAPD-PCR discriminated the isolates into 30 single isolates and 3 clusters at the level of 40% similarity. The EPEC isolates were highly diverse, as shown by their differing plasmid profiles, antibiotic resistance patterns and RAPD profiles.     

Increasing incidence and the mechanism of resistance of nalidixic acid resistant Shigella sonnei]

One hundred and fourteen Shigella sonnei strains obtained in 1991 to 2000 were tested for their susceptibilities to 12 antimicrobial agents. Nalidixic acid (NA) resistance was found in 2 of 15 strains (13.3%) in 1993, 2 of 8 strains (25%) in 1996, one of 5 strains (20%) in 1998, 7 of 21 strains (33.3%) in 1999 and 6 of 12 strains (50%) in 2000. The incidence of resistance to NA in S. sonnei strains increased significantly during this period. Among those 19 NA resistant strains, 11 strains were derived from patients with traveler's diarrhea and 8 strains were derived from patients who had not traveled abroad before the infection, namely domestic patients. PFGE analysis with Xba I revealed that all strains tested differentiated into two major clonal clusters, one cluster consisted of strains derived from patients who had traveled to India after 1993, and another cluster included strains derived from domestic patients. Mechanism of NA resistance was examined by sequencing the quinolone resistance-determining region (QRDR) of gyrA gene. Among 19 NA resistant strains tested, 11 strains presented a change at Ser-83 to Leu and 7 strains presented a change at Asp-87 to Try (5 strains) or Asn (2 strains), whereas 3 NA sensitive strains had no change in the region. These findings indicated that this mutation in gyrA plays an important role in acquisition of Nalidixic-acid resistance in clinical isolates of S. sonnei.     

Clusters of new tuberculosis cases in North-west London: a survey from three hospitals based on IS6110 RFLP typing

OBJECTIVES: The relative contributions of reactivation of latent infection and clusters of new infections to the overall incidence of tuberculosis in the U.K. is unknown. A study was carried out in North-West London to determine the feasibility of IS6110 RFLP strain typing as a tool to investigate the relative contributions of these two sources. METHODS: All available isolates of M. tuberculosis from specimens collected over a calendar year at three participating hospitals were typed by RFLP using an IS6110 probe. Isolates exhibiting a single band pattern were subject to further typing using an oligonucleotide direct repeat probe. Demographic and clinical information on cases was obtained from the National Survey of Tuberculosis Notifications in England and Wales and further information sought on clustered cases as identified by RFLP typing. RESULTS: Twenty-seven (23%) of the 118 cases had shared IS6110 RFLP patterns. Strains from nine cases had single band patterns, but these were all distinguishable from each other when subjected to further typing by direct repeat probe. The remaining 18 cases belonged to eight clusters. Epidemiological links were established between all the patients in each cluster. The likelihood of being in a cluster was increased in cases with pulmonary smear-positive disease. It was lower in cases of Indian Sub-continent ethnic origin. For 10 of the 18 clustered cases epidemiological links had not been established by conventional contact tracing. CONCLUSIONS: Investigation of the relative contributions of reactivation of latent infection and new infection is feasible in a UJK population, using IS6110 RFLP typing of M. tuberculosis isolates and epidemiological enquiries. This study in London identified clustered, presumably new cases, the majority of whom had not been linked epidemiologically. Comprehensive IS6110 RFLP typing of UK isolates would probably identify many clusters of incident tubercular infection.     

Molecular epidemiology of Haemophilus influenzae strains isolated from patients with meningitis during 1999 to 2003

A total of 535 Haemophilus influenzae strains from 226 Japanese institutions participating in the Nationwide Surveillance Study Group for Bacterial Meningitis were sent to our laboratory during 1999 to 2003. All strains were analyzed by PCR to identify the beta-lactam resistance genes, and their susceptibilities to beta-lactam agents were determined. These strains were classified into 6 genotype patterns and MIC90 values for ampicillin (ABPC): (i) beta-lactamase nonproducing, ABPC susceptible (BLNAS) strains and lacked all resistance genes (27.7% of isolates; MIC90, 0.5 microg/ml); (ii) beta-lactamase producing, ABPC resistant (BLPAR) strains (12.9%, 16 microg/ml); (iii) beta-lactamase nonproducing, ABPC resistant (Low-BLNAR) strains with a Asn526Lys amino acid substitution in ftsI gene encoding PBP3 (31.2%, 2 microg/ml); (iv) beta-lactamase nonproducing, ABPC resistant (BLNAR) strains with Ser385Thr and Asn526Lys substitutions in ftsI (17.2%, 8 microg/ml); (v) amoxicillin/clavlanic acid resistant (BLPACR I) strains, having beta-lactamase gene and a Asn526Lys amino acid substitution in ftsI (9.2%, 32 microg/ml); and (vi) amoxicillin/clavlanic acid resistant (BLPACR II), having beta-lactamase gene and ftsI substitutions as for BLNAR strains (1.9%, 64 microg/ml). All but 4 strains were serotype b. The prevalence of BLNAR strains has increased exponentially: 0% (n = 0/41) in 1999, 5.8% (n = 4/69) in 2000, 14.1% (n = 19/139) in 2001, 20.1% (n = 32/159) in 2002, and 29.1% (n = 37/127) in 2003. The MIC90s of BLNAR isolates except for ABPC were as follows: piperacillin, 0.125 microg/ml; ceftriaxone, 0.25 microg/ml; meropenem, 0.5 microg/ml; cefotaxime, 1 microg/ml; panipenem, 2 microg/ml; cefozopran, 16 microg/ml; and cefotiam, 64 microg/ml. To prevent such resistance from increasing, expedited vaccination, correct identification of the BLNAR molecularly, and the proper selection of proper antibiotics based on PK/PD must be taken.     

Population-based investigation of fluoroquinolones resistant tuberculosis in rural eastern China

Empirical use of fluoroquinolones (FQ) to treat a variety of bacterial infections may inadvertently select for FQ-resistant strains of Mycobacterium tuberculosis(MTB), especially in rural China where the use of FQ in treating infections has not been standardized. Here we determine the prevalence and describe the transmission of FQ-resistant MTB in two rural counties in eastern China through a combination of conventional epidemiology with IS6110-based restriction fragment length polymorphism(RFLP) analysis and DNA sequencing of drug-resistance determining regions. Phenotypic FQ resistance was detected in 31 of 351(8.8%) isolates. FQ resistance was equally distributed between patient-isolates deemed drug resistant and drug-susceptible, but mostly observed in those with treatment history of respiratory infection. Mutations in gyrA were found in 54.8% of FQ resistant isolates, and one isolate with a gyrB mutation. Despite predominating in entire bacilli population(69.2%), Beijing family strain had similar proportion of FQ resistance to the other(10.3% vs. 4.7%, p = 0.060). IS6110RFLP identified 2 clusters(4 isolates) among FQ resistant isolates and 3 clusters composed of both 4 FQ resistant isolates and 6 FQ susceptible isolates. Our results indicate that FQ-resistant MTB has emerged among the circulating bacillary population in rural eastern China. The relatively low level of clustering among FQ-resistant strains suggests most are acquired de novo, likely due to widespread FQ use.     

Emergence of community-associated methicillin-resistant Staphylococcus aureus USA 300 clone as a cause of health care-associated infections among patients with prosthetic joint infections

BACKGROUND: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as an important cause of staphylococcal infections, but there have been little data on whether CA-MRSA causes health care-associated infections. METHODS: A case-control study was performed to identify risk factors for prosthetic joint infections (PJI). Antibiograms of isolates associated with PJI were reviewed. Molecular typing of available MRSA isolates was done using pulsed field gel electrophoresis (PFGE). Nares cultures of health care workers who provided care to those orthopedic patients were obtained. RESULTS: Over a 13-month period (January 2003-January 2004), 9.5% of patients with prosthetic hip (THA) or knee (TKA) joint surgery developed PJI (7 TKA and 2 THA). The mean time to development of PJI was 20 days. Five infections were caused by CA-MRSA and 3 by methicillin-susceptible S aureus; one was culture negative. All CA-MRSA isolates had identical antibiograms (resistant to beta-lactams and erythromycin; susceptible to clindamycin, trimethoprim-sulfamethoxazole, rifampin, gentamicin, levofloxacin, and vancomycin). Molecular typing of 2 available CA-MRSA isolates revealed that these were the USA300 clone; these isolates were PVL+ and carried SCCmec IV. CA-MRSA was not recovered from nares cultures from 31 health care workers. In multivariate analysis, TKA (OR, 8.1; 95% CI: 1.3-48.1) and surgery time >180 minutes (OR, 7.4; 95% CI: 1.4-39.6) were associated with PJI. CONCLUSION: We have demonstrated that the CA-MRSA USA300 clone is no longer just a cause of community-acquired infections but has also emerged as a cause of health care-associated infections, causing PJI at our institution.