Expert Consensus on Polymyxin Antimicrobial Susceptibility Testing and Clinical Interpretation.

The polymyxins are important antimicrobial agents against antibiotic-resistant gram-negative bacilli. In 2020, the Clinical and Laboratory Standards Institute modified the clinical breakpoints for polymyxin susceptibility test by eliminating the "susceptible" interpretive category, only reporting intermediate (≤2 mg/L) and resistant (≥4 mg/L). However, the European Committee on Antimicrobial Susceptibility Testing recommended the use of clinical breakpoints of ≤2 mg/L as susceptible and >2 mg/L as resistant. The first-line laboratorians and clinicians in China have been perplexed by the inconsistence of international polymyxin clinical breakpoints and discouraged by the difficulty of conducting polymyxin susceptibility testing. Therefore, it is urgently needed to make it clear for the laboratorians in China to know how to accurately carry out polymyxin susceptibility testing and standardize the interpretation of susceptibility testing results. To this end, the experts from relevant fields were convened to formulate this consensus statement on the testing and clinical interpretation of polymyxin susceptibility. Relevant recommendations are proposed accordingly for laboratorians and clinicians to streamline their daily work.

The inoculum effect of antibiotics against CTX-M-extended-spectrum ß-lactamase-producing Escherichia coli.

BACKGROUND: Questions remain regarding the use of the cephalosporins to treat infections caused by extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli. For example, should ceftazidime or cefepime be used to treat infections with CTX-M ESBL-producing organisms with low MICs (minimum inhibitory concentrations), according to the new Clinical and Laboratory Standards Institute's (CLSI) recommendations for susceptibility testing? Some studies have reported that in vitro MICs of cephalosporins increase as the inoculum increases, which is the inoculum effect; however, most of the enzymes studied were SHV and TEM. In this study, we aimed to investigate the inoculum effect on ceftazidime, cefepime and four other ß-lactam agents against CTX-M-ESBLs-producing Escherichia coli. METHODS: Antibiotic susceptibilities were determined using broth microdilution MIC methodology according to the CLSI recommended with standard and 100-fold-higher inocula. RESULTS: An inoculum effect on meropenem and cefminox was not detected. The size of the inoculum affected piperacillin/tazobactam activity against only 4 strains, all CTX-M-14 genotypes. The inoculum size affected the activity of ceftazidime, cefepime and cefotaxime against 35%, 85%, 100% of strains, respectively. Among the strains with an inoculum effect, CTX-M-14 was the most common ESBL genotype. CONCLUSIONS: These findings suggest that meropenem is the most active compound against serious infections caused by Escherichia coli producing ESBLs. Cefminox and piperacillin-tazobactam exhibit strong activity against many strains. Until further studies are performed, clinicians should be aware that third- and fourth-generation cephalosporins (such as ceftazidime and cefepime) are not reliable for serious infections even though in vitro tests indicate susceptibility.

ISEcp1 element in association with bla(CTX-M) genes of E. coli that produce extended-spectrum ß-lactamase among the elderly in community settings.

INTRODUCTION: This study analyzed the relationship between the ISEcp1 element and bla(CTX-M) genes of Escherichia coli isolates that produce extended-spectrum ß-lactamase (ESBL) in community settings. METHODS: Nineteen E. coli isolates that produced CTX-M-type ß-lactamase were collected from four communities of elderly people in Shenyang, China. Polymerase chain reaction (PCR) amplification and direct sequencing were used to detect the insertion of the ISEcp1 element into the genetic environment of the bla(CTX-M) genes. RESULTS: The ISEcp1 element was associated with several bla(CTX-M) gene types, including CTX-M-14, CTX-M-24, CTX-M-22, and CTX-M-79. Sequence analysis revealed that all of the ISEcp1-like DNA sequences contained the putative promoter region that is involved in CTX-M genes transcription. ISEcp1 insertion sequences were observed 42-127bp upstream of the open reading frames (ORFs) that encode the CTX-M enzymes in all 15 strains. The CTX-M-79 ß-lactamase-encoding gene was observed with a different ISEcp1 insertion site and variable sequences between the ISEcp1 and bla(CTX-M-79) gene. For one strain (T298), the ISEcp1 element was disrupted by IS10. CONCLUSION: This work confirmed that the ISEcp1 elements were closely linked to bla(CTX-M) genes in community isolates from Shenyang, China.

Pharmacokinetic-pharmacodynamic profiling of four antimicrobials against gram-negative bacteria collected from Shenyang, China.

BACKGROUND: To examine common antimicrobial regimens used in eradicating certain nosocomial gram-negative pathogens and determine which ones are likely to be the most suitable as empirical choices in Shenyang, China. METHODS: A 5000-subject Monte Carlo simulation was conducted to determine the cumulative fraction of response (CFR) for meropenem, imipenem, cefepime, piperacillin/tazobactam and levofloxacin against Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Acinetobacter baumannii and Pseudomonas aeruginosa collected in 2006 and 2007 from Shenyang. RESULTS: Meropenem and imipenem had the highest CFRs against the Enterobacteriaceae (97%-100%), followed by cefepime. No antibiotic simulated regimen achieved optimal CFR against P. aeruginosa and A. baumannii. Piperacillin/tazobactam dosed at 4.5 g q8h achieved the lowest CFR against all bacteria. CONCLUSIONS: This study suggests that the carbapenems provide the greatest likelihood of clinical success for the Enterobacteriaceae, and combination therapy might be needed when choosing empirical therapy, especially when A. baumannii or P. aeruginosa are suspected.

[Molecular epidemiological study of multi-drug resistant Acinetobacter baumannii].

OBJECTIVE: To determine the possible genetic background and the source of our hospital's 43 clinical isolates of multidrug-resistant Acinetobacter baumannii, and the category of gene cassettes in type 1 integrons of all strains. METHODS: Restriction enzyme Apa I was chosen for all strains in pulsed-field gel electrophoresis (PFGE) methods. Multilocus sequence typing (MLST) was used to compare the allelic profiles of all the strains. PCR method was used for amplify the integrons of all strains. RESULTS: PFGE results showed that 43 strains were divided into four types. A-type and B-type were divided into 4 and 2 subtypes, respectively. The MLST results showed the existing of three allelic profiles: 1-3-3-2-2-7-3, 1-3-3-2-2-11-3, and 1-3-3-2-2-14-3. B-type and D-type of PFGE have the same allelic profile (1-3-3-2-2-11-3). A-type strains were detected mainly in ICU, and in burn unit only found B- and D-type. The same integron was detected in 62.8% of the strains. The constituent ratio of A1, A2, A3, A4, B1, B2, C and D-type was 40.7%, 18.5%, 7.4%, 3.7%, 14.8%, 3.7%, 3.7% and 7.4%, respectively. CONCLUSIONS: The coexistence of multiple cloning system in this region was proved by the PFGE and MLST, and the same clone can evolve to different subtypes when stimulated by different environmental conditions; and the different carrying-situation of the same integron in strains prove the possibility of the change during the evolution of resistance mechanisms.

[Novel gene sequence variants of pbp2b in penicillin-nonsusceptible Streptococcus pneumonia isolates].

OBJECTIVE: To investigate the alternations in gene/amino acid sequence of penicillin-binding protein (PBP)2b from clinical isolates of penicillin-nonsusceptible Streptococcus pneumonia (PNSP) in this region. METHODS: 24 strains of Streptococcus pneumonia were collected from January to December 2006. The antibiotics susceptibility of these strains was detected. PCR amplification and direct sequencing of pbp2b genes were performed. The sequence variations of PBP genes of the PNSP in this region were studied with sequence BLAST analysis. RESULTS: Three prominent substitutions were common to 13 PNSP isolates with minimal inhibitory concentration (MIC) at least 0.1 mg/L. These included the replacement of Thr(445)--> Ala following the conservative motif SSN, Glu(475)-->Gly and Thr(488)-->Ala/Ser. The exchange of Glu(332)-->Gly was identified in 12 PNSP isolates of which the MIC was at least 0. 25 mg/L. Seven penicillin resistant Streptococcus pneumonia (PRSP) isolates (MIC > or = 3 mg/L) shared the amino acid substitution Ala(618)-->Gly adjacent to third conserved (KTG) motif and the PBP2b sequences of seven PRSP isolates were classified within Baek's group II and were very similar to those of the Korean J77 isolate. Novel gene and amino acid sequence variants in isolate 14, 15, 8, 11 and 24 was identified in this study and these gene sequences have been deposited in the GenBank database and assigned accession no. EU035970, EU056919, EU056920, EU056921 and EU106886. CONCLUSION: Analysis of pbp2b genes revealed highly similar patterns of nucleotide and amino acid sequence variation among most resistant isolates, while penicillin intermediate Streptococcus pneumonia might be associated with novel gene sequence variants.

Involvement of p38 mitogen-activated protein kinase in E. coli-induced U937 apoptosis.

OBJECTIVE: To investigate whether the effect of E. coli on U937 cell lines apoptosis is mediated via p38 mitogen-activated protein kinase (MAPK) activation. METHODS: The U937 cell lines were treated with E. coli at different time or together with SB203580, an inhibitor for p38. Cell apoptosis was analyzed by flow cytometry. p38 activities were detected by Western blotting. RESULTS: E. coli induced apoptosis in cultured U937 cell lines in a time-dependent manner. The phosphorylation of p38 was induced after 10 minutes infection, reached the peak after 20 minutes, and started to decline after 30 minutes. In contrast, the level of total p38 protein was not changed in whole experimental period. Inhibition of p38 with SB203580 significantly inhibited E. coli induced apoptosis in U937 cells. CONCLUSION: The activation of the p38 MAPK in U937 cell lines by E. coli is a major pathway to mediate the apoptosis.

[Expression of nuclear factor-kappa B and effect of pyrrolidine dithiocarbamate in Pseudomonas aeruginosa pneumonia rat model].

OBJECTIVE: To investigate the expression of nuclear factor-kappa B (NF-kappaB) and cytokines in Pseudomonas aeruginosa (PA)-induced pneumonia of rats, and the effect of pyrrolidine dithiocarbamate (PDTC). METHODS: Seventy-two male SD rats were divided into three groups at random:a control group, a PA group and a PDTC group (n = 24 each). The PA induced pneumonia model was established in SD rats. The rats of the control group and the PA group were intraperitoneally given saline (1 ml) at 60 min before PA exposure, while the rats of the PDTC group received the same volume of PDTC (200 mg/kg). After 60 min, the rats of the PA group and the PDTC group were intratracheally instilled with PA 0.2 ml (6 x 10(8) CFU/ml), while the rats of the control group received the same volume of saline. At 3 h, 6 h, 16 h, 24 h after PA exposure, the rats were examined. Then they were sacrificed and the lung were excised for routine histological analysis. Immunohistochemical staining with an antibody against activated NF-kappaB and Western blot were performed to detect the expression of NF-kappaB. The change of TNFalpha mRNA was identified by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Histological findings demonstrated that the lung exposed to PA showed significant changes in the lung structure, edema and pronounced inflammatory cell infiltration. Both symptoms and damages of the lung were less severe in the rats of PDTC group than those of the PA group. Compared with the PDTC group, the activation of NF-kappaB and the expression of TNFalpha in the PA group were significantly upregulated after PA challenge 3 - 24 h (P < 0.01), respectively; peak expression of NF-kappaB and TNFalpha were observed at 3 - 6 h after PA exposure. CONCLUSIONS: The expression of NF-kappaB and TNFalpha induced by NF-kappaB play an important role in the pathogenesis of pneumonia. The inhibitor of NF-kappaB, PDTC, can relieve the lung damages produced by pneumonia.

[Replacement of third-generation cephalosporins by piperacillin-tazobactam decreases colonization of extended-spectrum beta-lactamases-producing intestinal Escherichia coli].

OBJECTIVE: To investigate the role of replacement of third-generation cephalosporins by piperacillin-tazobactam (pip-tazo) in influencing the colonization of extended-spectrum beta-lactamases (ESBLs)-producing Escherichia coli (E. coli) in intestinal tract. METHODS: The study was divided into two phases lasting altogether 9 months, namely the pre-replacement phase (phase I, 3 months) and replacement phase (phase II, 6 months). In the latter phase, third-generation cephalosporins was restricted and replaced by pip-tazo. In phase I and phase IIb (the last 3 months of phase II), clinical data and rectal swab were taken for E. coli isolation as follow: within 24 hrs after admission (baseline screening), every week and 48 hrs before discharge. ESBLs production was detected with double disc test. Acquisition rate of ESBLs-producing E. coli were calculated both in ES1 group (patients' rectal swab collected and tests at least 2 times) and ES2 group (ES1 but with negative ESBLs either at the time of screening on admission or at anytime during the hospital stay). Continuous variable was compared using unpaired t-test and categorical variables was compared using Pearson Chi square test. Fisher's exact test was used in the two phases. RESULTS: In phase IIb, as compared with in phase I, the total consumption of antibiotics other than pip-tazo was reduced by 38.40%, the third-generation cephalosporins consumption was reduced by 70.11%, but pip-tazo consumption was raised by 895.35%. Meanwhile, the acquisition rate of ESBLs-producing E. coli in rectal swab was significantly decreased in phase IIb as compared with phase I (11.4% vs 24.0%) in ES1 group and the same is true in ES2 group (11.8% vs 27.9%). CONCLUSION: Replacement of third-generation cephalosporin with pip-tazo can reduce colonization of ESBLs--producing E. coli in intestinal tract.

[Effects of insulin-like growth factor-1 and insulin on modulating glucose metabolism and functions of lung fibroblasts].

OBJECTIVE: It is recognized that lung fibroblasts (LF) act as a common pathway in the development of fibrosis from alveolitis of whatever etiology. The study was undertaken to identify the modulating effects of insulin-like growth factor-1 (IGF-1) on LF glucose metabolism and functions, to explore possible therapeutic targets through modulating LF for the treatment of pulmonary fibrosis. METHODS: Human embryonic lung (HEL) diploid fibroblast cells were cultured for 24 h with blank control, 100 ng/ml IGF-1, 200 ng/ml IGF-1, 100 ng/ml IGF-1 + 100 ng/ml insulin, 100 ng/ml IGF-1 + 200 ng/ml insulin, 100ng/ml insulin, 200 ng/ml insulin, respectively. The culture supernatants and cell pellets were collected to extract proteins and mRNAs. After quantitated with ultraviolet spectrometer, RT-PCR and Northern blotting were performed to determine the content of glucose transporter-4 (Glut-4), hexokinase II, elastin and collagen-IV. RESULTS: RT-PCR showed that the general mean absorbance ratios of Glut-4 and HK-IImRNA in IGF-1 group were (0.67 +/- 0.25) and (0.60 +/- 0.19), significantly increased as compared with that of control group [(0.61 +/- 0.12), (0.55 +/- 0.19)]; but decreased as compared with that of insulin group [(0.74 +/- 0.26), (0.71 +/- 0.23)]. The expression of elastin, collagen protein in IGF-1 group [(174.3 +/- 4.2), (142.1 +/- 1.0)] were significantly stronger than that of insulin group. CONCLUSIONS: IGF-1 can stimulate LF glucose metabolism, companied with increased expression of elastin and collagen IV in a concentration-dependent manner. IGF-1 can decrease the effect of insulin on LF glucose metabolism, whereas insulin can attenuate the effect of IGF-1 on LF in elastin and collagen expression.

Sharp instrument injuries among hospital healthcare workers in mainland China: a cross-sectional study.

OBJECTIVES: To determine the prevalence of sharp instrument injuries in hospital-based healthcare workers (HCWs) in mainland China and the contributing factors. DESIGN: Cross-sectional study. SETTING: The data were derived from public hospitals. PARTICIPANTS: A total of 360 hospitals were recruited in the study, including 289 general hospitals and 71 specialised hospitals. Among them, 194 are tertiary-level hospitals and 166 are secondary level. The study population finally consisted of 223 149 hospital HCWs. PRIMARY OUTCOME MEASURES: A questionnaire was designed based on the aim of the study. Profession of HCWs, workplace, circumstance and medical apparatus and instrument were covered in the survey. HCWs completed a self-administered questionnaire regarding details of sharp instrument injuries within the previous month. Prevalence estimates for the injuries were calculated for the overall HCWs and for subgroups according to profession, workplace, circumstance or instrument. RESULTS: Within the included HCWs, the prevalence of sharp instrument injuries was 0.08 per person-month. Only 4.6% of the HCWs reported to their hospitals after injury. The highest number of injuries occurred in nursing staff (10.3%). Injuries took place most frequently on general wards (44.5%). The circumstances that involved most frequent injuries include surgical needle insertion, removing an arteriovenous needle from a patient and recapping the needle. Single-use syringe caused more injuries incidents than other instruments. CONCLUSIONS: These results indicate that sharp instrument injuries have become a major occupational problem of HCWs in mainland China. Attentions need to be paid to the issue and strategies for preventing such injuries are needed.

Spectrum and antimicrobial resistance of common pathogenic bacteria isolated from patients with acute exacerbation of chronic obstructive pulmonary disease in mainland of China.

BACKGROUND: Bacteria-induced respiratory infection has been long considered to be the major cause of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Therefore, a clear picture about the distribution and drug-resistance of pathogenic bacteria in the lower airways should be helpful for treatment of the disease. So far, data on this topic among Chinese are lacking. METHODS: A surveillance study was performed in consecutive patients with AECOPD at five areas in China between October 2006 and April 2008. The sputum from these patients was cultured and isolated for bacteria. Agar dilution method was used to determine the minimal inhibitory concentrations (MICs) of levofoxacin and other 15 antibiotics against these strains. RESULTS: Three hundred and fifty-nine pathogenic bacterial strains were isolated among 884 patients with AECOPD. The predominant bacteria were Pseudomonas aeruginosa (21.7%), Klebsiella pneumoniae (12.3%), Haemophilus influenzae (14.2%) and Streptococcus pneumoniae (11.7%), followed by Haemophilus parainfluenzae (9.5%), Acinetobacter baumannii (7.8%), Moraxella catarrhalis (6.4%) and Escherichia coli (3.6%). The majority of bacterial pathogens isolated in this study were susceptible to fuoroquinolones, ceftazidime, cefepime and imipenem. CONCLUSIONS: Gram-negative bacilli are the leading pathogens in patients with AECOPD in China. Haemophilus parainfluenzae may be one of the most important pathogens in AECOPD. This study provides evidence for local surveillance of AECOPD pathogens and appropriate choice of antimicrobials in China.

An uncontrolled open-label, multicenter study to monitor the antiviral activity and safety of inhaled zanamivir (as Rotadisk via Diskhaler device) among Chinese adolescents and adults with influenza-like illness.

BACKGROUND: It is the first multicenter clinical study in China to investigate zanamivir use among Chinese adolescents and adults with influenza-like illness (ILI) since 2009, when inhaled zanamivir (RELENZA(®)) was marketed in China. METHODS: An uncontrolled open-label, multicentre study to evaluate the antiviral activity, and safety of inhaled zanamivir (as Rotadisk via Diskhaler device); 10 mg administered twice daily for 5 days in subjects ≥ 12 years old with ILI. Patients were enrolled within 48 hours of onset and followed for eight days. Patients were defined as being influenza-positive if the real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) test had positive results. RESULTS: A total of 400 patients ≥ 12 years old were screened from 11 centers in seven provinces from March 2010 to January 2011. Three hundred and ninety-two patients who took at least one dose of zanamivir were entered into the safety analysis. The mean age was 33.8 years and 50% were male. Cardiovascular diseases and diabetes were the most common comorbidities. All the reported adverse events, such as rash, nasal ache, muscle ache, nausea, diarrhea, headache, occurred in less than 1% of subjects. Mild sinus bradycadia or arrhythmia occurred in four subjects (1%). Most of the adverse events were mild and did not require any change of treatment. No severe adverse events (SAE) or fatal cases were reported. Bronchospasm was found in a 38 years old woman whose symptoms disappeared after stopping zanamivir and without additional treatment. All the 61 influenza virus isolates (43 before enrollment, 18 during treatment) proved to be sensitive to zanamivir. CONCLUSIONS: Zanamivir is well tolerated by Chinese adolescents and adults with ILIs. There is no evidence for the emergence of drug-resistant isolates during treatment with zanamivir.

Molecular characteristics and resistant mechanisms of imipenem-resistant Acinetobacter baumannii isolates in Shenyang, China.

The investigation was carried out to elucidate the molecular characteristics and resistant mechanisms of imipenem-resistant Acinetobacter baumannii. Thirty-seven isolates were collected from January 2007 to December 2007. The homology of the isolates was analyzed by both pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The genes of ß-lactamases, adeB, and class 1 integron were polymerase chain reaction amplified. Genotype analysis of the 37 A. baumannii isolates by PFGE revealed the circulation of four PFGE types (A-D); the A- and B-type accounted for 48.6% and 40.5%, respectively. MLST showed the existence of three allelic profiles. The agar dilution method was carried out to determine the MIC of imipenem, in the absence or presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP, 10 µg/ml). The MICs of the strains to imipenem were between 16 µg/ml and 128 µg/ml. When CCCP was added, a MIC decrease of at least four-fold was observed in 20 isolates, which belonged to the A- or C-type. AdeB and bla (PER-1) genes were each detected in 35 isolates, bla (OXA-23) gene in 34 isolates and bla (OXA-58)-like gene in 24 isolates. All isolates harbored bla (OXA-51)-like genes. No isolates carried the bla (IMP-1) gene. Integron was detected in 25 isolates, which mediated the resistance to aminoglycosides and rifampin. The epidemiologic data suggested that the increasing infection of A. baumannii in our hospital was mainly caused by the inter-hospital spread of two epidemic clones. The AdeABC efflux system may be the important factor that leads to the high level of imipenem-resistance in PFGE A-type.

Molecular characteristics of penicillin-binding protein 2b, 2x, and 1a sequences in penicillin-nonsusceptible Streptococcus pneumoniae isolates in Shenyang, China.

The aim of this study was to investigate the nature of the amino acid motifs found in penicillin-binding proteins (PBP) 2b, 2x, and 1a of penicillin-nonsusceptible Streptococcus pneumoniae isolates from Shenyang, China, and to obtain information regarding the prevalence of alterations within the motifs or in positions flanking the motifs. For 18 clinical isolates comprising 4 penicillin-susceptible S. pneumoniae, 5 penicillin-intermediate S. pneumoniae, and 9 penicillin-resistant S. pneumoniae. the DNA sequences of PBP2b, PBP2x, and PBP1a transpeptidase domains were determined and then genotyped by multilocus sequence typing. Sequence analysis revealed that most penicillin-nonsusceptible S. pneumoniae isolates (penicillin MIC > or = 1.5 microg/mL and cefotaxime MIC > or = 2 microg/mL) shared identical PBP2b, PBP2x, and PBP1a amino acid profiles. Most penicillin-resistant S. pneumoniae isolates were ST320 (4-16-19-15-6-20-1), the double-locus variant of the Taiwan19F-14 clone. This study will serve as a basis for future monitoring of genetic changes associated with the emergence and spread of beta-lactam resistance in Shenyang, China.

Prevalence of rectal carriage of extended-spectrum beta-lactamase-producing Escherichia coli among elderly people in community settings in China.

The importance of community-acquired infections due to extended-spectrum beta-lactamase-producing (ESBL) Escherichia coli has been increasingly recognized in recent years. No comprehensive data are available on the prevalence, risk factors, and genotypes of ESBL production in community residents in China. Rectal samples from 270 elderly people were collected in four communities in Shenyang (China). Colonies were screened by double-disk synergy test for ESBL production and then, ESBLs were characterized by PCR and sequencing. The clonal relatedness of all ESBL-producing isolates was determined by pulsed-field gel electrophoresis. Potential risk factors for rectal carriage of ESBL producers were examined by multivariate analysis. The prevalence of rectal carriage of ESBL-producing E. coli was 7.0%. All 19 ESBL-producing isolates produced CTX-M-type ESBLs, including CTX-M-14 (11 strains), CTX-M-22 (3 strains), CTX-M-79 (3 strains), CTX-M-24 (1 strain), and CTX-M-24 and CTX-M-79 together (1 strain). CTX-M-79 ESBL was first detected worldwide. ESBL-producing strains were clonally unrelated. Appearance of ESBL producers is strongly associated with the use of antibiotics in the past 3 months (odds ratio 3.2, 95% CI 1.1-9.0, P = 0.03). Our results show the importance of the intestinal tract as a reservoir for ESBL-producing isolates in community settings in China and that the use of antibiotics in the past 3 months is clearly linked to rectal carriage of ESBL producers.