Christian G Giske

Publications (54)180.77 Total impact

• Article: Rational use of aminoglycosides-Review and recommendations by the Swedish Reference Group for Antibiotics (SRGA).

  Håkan Hanberger, Charlotta Edlund, Mia Furebring, Christian G Giske, Asa Melhus, Lennart E Nilsson, Johan Petersson, Jan Sjölin, Anders Ternhag, Maria Werner, Erik Eliasson
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  ABSTRACT: The Swedish Reference Group for Antibiotics (SRGA) has carried out a risk-benefit analysis of aminoglycoside treatment based on clinical efficacy, antibacterial spectrum, and synergistic effect with beta-lactam antibiotics, endotoxin release, toxicity, and side effects. In addition, SRGA has considered optimal dosage schedules and advice on serum concentration monitoring, with respect to variability in volume of drug distribution and renal clearance. SRGA recommends that aminoglycoside therapy should be considered in the following situations: (1) progressive severe sepsis and septic shock, in combination with broad-spectrum beta-lactam antibiotics, (2) sepsis without shock, in combination with broad-spectrum beta-lactam antibiotics if the infection is suspected to be caused by multi-resistant Gram-negative pathogens, (3) pyelonephritis, in combination with a beta-lactam or quinolone until culture and susceptibility results are obtained, or as monotherapy if a serious allergy to beta-lactam or quinolone antibiotics exists, (4) serious infections caused by multi-resistant Gram-negative bacteria when other alternatives are lacking, and (5) endocarditis caused by difficult-to-treat pathogens when monotherapy with beta-lactam antibiotics is not sufficient. Amikacin is generally more active against extended-spectrum beta-lactamase (ESBL)-producing and quinolone-resistant Escherichia coli than other aminoglycosides, making it a better option in cases of suspected infection caused by multidrug-resistant Enterobacteriaceae. Based on their resistance data, local drug committees should decide on the choice of first-line aminoglycoside. Unfortunately, aminoglycoside use is rarely followed up with audiometry, and in Sweden we currently have no systematic surveillance of adverse events after aminoglycoside treatment. We recommend routine assessment of adverse effects, including hearing loss and impairment of renal function, if possible at the start and after treatment with aminoglycosides, and that these data should be included in hospital patient safety surveillance and national quality registries.
  Scandinavian Journal of Infectious Diseases 12/2012; · 1.72 Impact Factor
• Article: Age and risk factors influence the microbial etiology of blood stream infection in children.

  Joachim Luthander, Rutger Bennet, Christian G Giske, Anna Nilsson, Margareta Eriksson
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  ABSTRACT: AIM: To study the etiology of bloodstream infections (BSI) in children 0-17 years, the influence of age and underlying co-morbidity on BSI rate, distribution of pathogens and outcome; and to provide data on antimicrobial susceptibility patterns. METHODS: A retrospective population-based study. Data on blood cultures were collected at yearly intervals during 1998-2008. Information about risk factors, focal infection and outcome was retrieved from the patient charts. RESULTS: We identified 1097 BSI. The incidence of BSI was 0.4 /1000. The age-specific incidence was 2.3/1000 in neonates (0-28 days old) and 0.2/1000 in the age group 6-17 years. S.aureus was the most common pathogen. The number of species causing BSI in previously healthy children was lower compared to children with co-morbidity. Most children requiring intensive care had a serious underlying illness. Antimicrobial resistance was rare and did not influence outcome. The case-fatality rate was 14.4% in neonates, 5.4 % in children with co-morbidity and 1.7% in previously healthy children. CONCLUSION: Mortality from BSI is low and a limited spectrum of pathogens is isolated from previously healthy children compared to children with co-morbidity. When choosing empiric therapy for suspected BSI, age and presence of risk factors should be taken into account. © 2012 The Author(s)/Acta Paediatrica © 2012 Foundation Acta Paediatrica.
  Acta Paediatrica 11/2012; · 2.07 Impact Factor
• Article: Evaluation of ROSCO Neo-Sensitabs for phenotypic detection and subgrouping of ESBL-, AmpC- and carbapenemase-producing Enterobacteriaceae.

  Frank Hansen, Anette M Hammerum, Robert L Skov, Christian G Giske, Arnfinn Sundsfjord, Orjan Samuelsen
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  ABSTRACT: The increasing prevalence of ESBL-, AmpC- and carbapenemase-producing Enterobacteriaceae necessitates reliable phenotypic tests for detection and categorization. The main objective of this study was to evaluate ROSCO Neo-Sensitabs with different β-lactam-β-lactam inhibitor combinations for phenotypic detection and categorization of β-lactamases in Enterobacteriaceae. Using standard CLSI/EUCAST methodology, differences in zones of inhibitions between a β-lactam alone compared with the combination with a β-lactamase inhibitor as well as subjective synergy observations were determined for 172 well characterized Enterobacteriaceae strains with defined resistance mechanisms. The results showed that for all ESBL-positive strains (n = 66), combinations of clavulanic acid synergy with cefotaxime, ceftazidime or cefepime, were observed. All acquired AmpC β-lactamases (n = 17) were detected using cloxacillin combined with cefotaxime and/or ceftazidime (both combinations were required). Carbapenemase producers (n = 59) with the exception of one KPC-producer were correctly grouped using the combination of meropenem ± aminophenylboronic acid (APBA) or dipicolinic acid (DPA). Ethylene diamine tetraacetic acid (EDTA) also inhibited all metallo-β-lactamases, but as with DPA, one false positive result was observed. Based upon these data, we propose a tablet layout for 14 cm agar plates, which could be used as a whole or in a targeted approach for detection and categorizing of relevant acquired β-lactamases in Enterobacteriaceae.
  Apmis 09/2012; 120(9):724-32. · 1.99 Impact Factor
• Article: Prevalence of antibiotic-resistant bacteria in residents of nursing homes in a Swedish municipality: healthcare staff knowledge of and adherence to principles of basic infection prevention.

  Helene Andersson, Christina Lindholm, Aina Iversen, Christian G Giske, Åke Örtqvist, Mats Kalin, Bjöörn Fossum
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  ABSTRACT: The aims of this study were to investigate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in residents living in Swedish nursing homes, and if carriage of resistant bacteria was related to antibiotic treatment, other risk factors, and/or staff's adherence to guidelines for infection control. Five hundred and sixty residents from 9 nursing homes on a total of 67 wards participated in the study and had microbiological cultures taken. Faecal samples were obtained from 495 residents (88.3%). ESBL-positive residents were followed for 2 y with repeated sampling. Two hundred and ninety-six [corrected] staff members were interviewed and observed regarding familiarity with and adherence to infection control guidelines. No resident was positive for MRSA or VRE. Fifteen of the residents were found to be ESBL-positive. Residents living on wards where ESBL-positive residents were identified had been treated more frequently with antibiotics (42%), compared to those on wards where no residents with ESBL were found (28%; p = 0.02). ESBL-positive Escherichia coli isolates from residents living in adjacent rooms were found to be closely genetically related when analysed by pulsed-field gel electrophoresis, indicating transmission between residents. Staff adherence to infection control guidelines sometimes revealed shortcomings, but no significant differences regarding compliance to the guidelines could be found. Carriage of resistant bacteria was uncommon and only ESBL-producing Enterobacteriaceae were identified in Swedish nursing homes. Usage of antibiotics was higher on wards where ESBL-positive residents were detected and there was an indication of transmission of ESBL between residents.
  Scandinavian Journal of Infectious Diseases 06/2012; 44(9):641-9. · 1.72 Impact Factor
• Article: Diverse sequence types of Klebsiella pneumoniae contribute to the dissemination of blaNDM-1 in India, Sweden, and the United Kingdom.

  Christian G Giske, Inga Fröding, Chowdhury Mehedi Hasan, Agata Turlej-Rogacka, Mark Toleman, David Livermore, Neil Woodford, Timothy R Walsh
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  ABSTRACT: Clinical isolates of Klebsiella pneumoniae producing NDM-1 carbapenemase from India (n = 22), the United Kingdom (n = 13), and Sweden (n = 4) were subjected to multilocus sequence typing (MLST), automated repetitive sequence-based PCR (rep-PCR), serotyping, virulence gene screening, and plasmid replicon typing. The most frequently detected MLST sequence types (STs) were ST14 (n = 13; all serotype K2), ST11, ST149, ST231, and ST147. The correlation between MLST and automated rep-PCR was excellent. IncA/C was the most frequently detected plasmid replicon type (n = 14). ST14, ST11, and other successful clones may be important for the dissemination of bla(NDM-1).
  Antimicrobial Agents and Chemotherapy 02/2012; 56(5):2735-8. · 4.84 Impact Factor
• Article: Hematological: Low all-cause mortality and low occurrence of antimicrobial resistance in hematological patients with bacteremia receiving no antibacterial prophylaxis: a single-center study.

  Christian Kjellander, Magnus Björkholm, Honar Cherif, Mats Kalin, Christian G Giske
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  ABSTRACT: Bacteremia is a major cause of morbidity and mortality in patients with hematological malignancies. The aim of this study was to define temporal trends in species distribution, antimicrobial susceptibility, and all-cause mortality in bacteremic hospitalized patients receiving no antibacterial prophylaxis during chemotherapy-induced neutropenia. A total of 677 clinical episodes of bacteremia were identified in 463 patients during 2002-2008, and the results were compared with those published from the same institution during 1980-86 and 1988-2001. No major changes in patient selection were introduced during this period. Between 2002 and 2008, the dominating pathogens were Escherichia coli (18%), coagulase-negative staphylococci (15%), viridans streptococci (14%), Klebsiella spp. (10%), and Enterococcus faecium (8%). The 7-d crude mortality rate was 5.2%. Polymicrobial bacteremia was seen in 25.7% of the patients who died within 7 d and in 13.1% of the survivors (P = 0.04). Acquired resistance was rarely observed, but a statistically significant increase in ciprofloxacin resistance in E. coli was observed. Comparing 2002-2008 with historical data from the same institution, the proportion of Gram-positive isolates remained stable at 53-55% from 1988. The avoidance of fluoroquinolone prophylaxis may have contributed to a stable proportion of Gram-positive bacteremia. The crude mortality was low in an international perspective. Acquired resistance was uncommon, but ciprofloxacin resistance in E. coli increased significantly. We believe that an indiscriminate use of antibacterial prophylaxis could be avoided in neutropenic patients without a negative impact on mortality.
  European Journal Of Haematology 02/2012; 88(5):422-30. · 2.61 Impact Factor
• Article: Fecal Carriage of ESBL-Producing E. coli and K. pneumoniae in Children in Guinea-Bissau: A Hospital-Based Cross-Sectional Study.

  Joakim Isendahl, Agata Turlej-Rogacka, Cristovão Manjuba, Amabelia Rodrigues, Christian G Giske, Pontus Nauclér
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  ABSTRACT: In recent years, the world has seen a surge in extended-spectrum β-lactamase (ESBL)-producing bacteria. However, data on the dissemination of ESBL-producing Enterobacteriaceae in the community from systematically enrolled study subjects in Africa remains limited. To determine the prevalence, phenotypic resistance patterns and genetic characteristics of ESBL-producing E. coli and K. pneumoniae in fecal carriage and to analyze associated risk factors in children attending a pediatric emergency department in Guinea-Bissau. From June to September 2010, children <5 years of age with fever or tachycardia attending a pediatric emergency ward during the day was screened for ESBL carriage in feces. Socio-demographic and health seeking behavior data was collected. Antibiotic susceptibility was tested with VITEK2 and EUCAST disk diffusion method, molecular characterization of ESBL-encoding genes was performed with multiplex PCR and clonal relatedness was established by automated rep-PCR. Of 408 enrolled children 133 (32.6%) were ESBL carriers. In total, 83 E. coli and 91 K. pneumoniae ESBL-producing isolates were obtained. Nearly all isolates were multidrug-resistant. Co-resistance to ciprofloxacin, trimethoprim-sulfamethoxazole and aminoglycosides was common. Of the isolates, 38.5% were co-resistant to these classes plus extended-spectrum cephalosporins, which infers resistance to all easily available antibiotic agents for treatment of gram-negative sepsis in Guinea-Bissau. The predominant resistance-encoding gene subgroup was bla(CTX-M-1) and epidemiologic typing showed that the bacterial ESBL population was highly diverse both for E. coli and K. pneumoniae. Bed sharing with another child <5 years of age was a risk factor for ESBL carriage, indicating crowding as a potential risk factor for transmission of ESBL-producing bacteria. Prevalence of ESBL-producing bacteria in this population was high and clonally diverse. This is alarming considering the limited diagnostic and treatment possibilities in Guinea-Bissau and other resource-poor countries.
  PLoS ONE 01/2012; 7(12):e51981. · 4.09 Impact Factor
• Article: Efficacy of pivmecillinam for treatment of lower urinary tract infection caused by extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae.

  Emilia Titelman, Aina Iversen, Mats Kalin, Christian G Giske
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  ABSTRACT: To evaluate the clinical and bacteriological efficacy of pivmecillinam against lower urinary tract infection (UTI) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, patients treated for lower UTI with pivmecillinam (n=8) were studied. Patients treated with nitrofurantoin (n=3) and trimethoprim (n=3) or a combination of these agents with pivmecillinam (n=3) were included as a control group. Antimicrobial susceptibility was determined with EUCAST methodology. Bacteriologic cure was defined as <10(3) CFU/ml at follow-up (30 days), and clinical cure as resolved UTI symptoms after completed treatment. All patients receiving pivmecillinam had good clinical response (8/8), but bacteriological cure rates were low (2/8). However, none of the patients with persisting bacteriuria had a relapse of UTI symptoms within 6 months. All isolates were susceptible to the given antimicrobial. Most isolates belonged to the CTX-M-1 group (n=11, 65%) or CTX-M-9-group (n=4, 24%). Four E. coli isolates belonged to the international clone O25b-ST131 (25%). In conclusion, pivmecillinam had good clinical activity against lower UTI caused by ESBL-producing Enterobacteriaceae, but bacteriological cure rates were low. The persistent bacteriuria appears to be of little clinical importance, but larger clinical studies are needed to determine the usefulness of pivmecillinam in infections caused by ESBL-producing bacteria.
  Microbial drug resistance (Larchmont, N.Y.) 12/2011; 18(2):189-92. · 1.99 Impact Factor
• Article: Antimicrobial susceptibility to parenteral and oral agents in a largely polyclonal collection of CTX-M-14 and CTX-M-15-producing Escherichia coli and Klebsiella pneumoniae.

  Emilia Titelman, Aina Iversen, Gunnar Kahlmeter, Christian G Giske
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  ABSTRACT: Activity of oral and parenteral antimicrobials against consecutively isolated extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (n = 149) and Klebsiella pneumoniae (n = 20) was determined, and susceptibility test methods were compared for parenteral β-lactams. Polymerase chain reaction (PCR) targeting bla(CTX-M), bla(SHV) and bla(TEM), and DNA sequencing and epidemiological typing with pulsed-field gel electrophoresis were performed. PCR targeting pabB was screened for E. coli O25b-ST131. Minimum inhibitory concentrations (MICs) were determined using Etest and broth microdilution. Disc diffusion was performed according to European Committee on Antimicrobial Susceptibility Testing (EUCAST). Dominating genotypes were bla(CTX-M-15) (75%) and bla(CTX-M-14) (23%). Four E. coli clusters (7-18 isolates) were found. Forty-two per cent of E. coli belonged to O25b-ST131. Ciprofloxacin resistance was 72%, trimethoprim resistance was 70%. Among E. coli, resistance to mecillinam (13%), nitrofurantoin (7%) and fosfomycin (3%) was low, although resistance was high in K. pneumoniae (25%, 60%, 85%). Susceptibility to ertapenem was 99%, piperacillin-tazobactam 91%, tigecycline 96% and temocillin 76%. Susceptibility rates obtained with broth microdilution and Etest were in agreement for cefotaxime (2 vs 1%) and ceftazidime (9 vs 11%), but not for piperacillin-tazobactam (59 vs 91%). With disc diffusion major errors occurred with piperacillin-tazobactam (18/169). Several therapeutic alternatives exist for ESBL-producing E. coli, but few exist for K. pneumoniae. Disc diffusion and Etest can accurately predict susceptibility to cefotaxime and ceftazidime, but not to piperacillin-tazobactam with the present breakpoints.
  Apmis 12/2011; 119(12):853-63. · 1.99 Impact Factor
• Source

  Available from: Kristian Angeby

  Article: Wild-type MIC distributions must be considered to set clinically meaningful susceptibility testing breakpoints for all bacterial pathogens, including Mycobacterium tuberculosis.

  Kristian Angeby, Christian G Giske, Pontus Juréen, Thomas Schön, Jotam G Pasipanodya, Tawando Gumbo
  Antimicrobial Agents and Chemotherapy 09/2011; 55(9):4492-3; author reply 4493. · 4.84 Impact Factor
• Article: A diversity of OXA-carbapenemases and class 1 integrons among carbapenem-resistant Acinetobacter baumannii clinical isolates from Sweden belonging to different international clonal lineages.

  Nabil Karah, Christian G Giske, Arnfinn Sundsfjord, Ørjan Samuelsen
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  ABSTRACT: This study was aimed to investigate the molecular epidemiology, mechanism of carbapenem resistance, and occurrence of class 1 integrons among 13 carbapenem-resistant clinical isolates of Acinetobacter baumannii obtained between 2004 and 2007 from Sweden. Nine isolates were linked with hospitalization abroad. Molecular epidemiology was investigated by multilocus sequence typing, multiplex PCRs for major international clones/sequence groups (SGs), and pulsed-field gel electrophoresis. OXA-carbapenemase genes/genetic surroundings and class 1 integrons were examined by PCRs and sequencing. The isolates belonged to sequence type (ST) 2/international clone II (n=6), ST23/SG5 (n=2), ST25 (n=2), ST5/SG7 (n=1), and ST109 (n=2). OXA-58, OXA-23, and OXA-24 were detected in seven, five, and one isolate, respectively. Different genetic structures surrounded the bla(OXA-58-like) and bla(OXA-23-like) genes. Interestingly, ISAba825 was detected upstream bla(OXA-58-like) in two isolates. Class 1 integrons with three different variable regions (VR) were detected. VR1 (aacA4-orfO-bla(OXA-20)) was found in four isolates from ST2/international clone II, with three of them imported from Greece. VR2 (aadB-aadA1-IS) was detected in one ST5 isolate imported from Poland, and VR3 (bla(GES-11)-aacA4-dfrA7) was present in a nonimport ST25 isolate. In conclusion, a variety of clonal lineages, OXA-carbapenemases genes and genetic structures, and class 1 integrons were detected among carbapenem-resistant A. baumannii from Sweden.
  Microbial drug resistance (Larchmont, N.Y.) 08/2011; 17(4):545-9. · 1.99 Impact Factor
• Article: When and how to cover for resistant gram-negative bacilli in severe sepsis and septic shock.

  Håkan Hanberger, Christian G Giske, Helen Giamarellou
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  ABSTRACT: In the 80s and 90s, increasing antibiotic resistance was met by the introduction of new effective agents with broader antibacterial spectra for the empirical treatment of severe infections. In recent years, however, few novel antimicrobials have been developed, and this has critically weakened our strength in the fight against resistant bacteria, especially Gram-negative bacilli. It has been well proven that mortality increases if initial empirical antibiotic treatment for severe infection is inappropriate due to resistance of the pathogen. Physicians are already faced with the increasing challenge of untreatable or almost untreatable Gram-negative infections due to antibiotic resistance. Empirical treatment with broader spectra and high antibiotic pressure both in- and outside hospital is the driving force behind resistance. Since new efficient drugs against Gram-negative bacilli will not be available for some time, the best we can do to stop infections caused by multidrug-resistant bacteria is to improve infection control and choice of antibiotics, which should be based on surveillance of local antibiotic consumption and resistance. We must learn more about the revived antibacterial agents colistin and fosfomycin, and the few next generation Gram-negative antibiotics that have been developed. The aim of this review is to give an update on present therapeutic options in the fight against multidrug-resistant Gram-negative bacteria.
  Current Infectious Disease Reports 07/2011; 13(5):416-25.
• Article: Setting interpretive breakpoints for antimicrobial susceptibility testing using disk diffusion.

  Göran Kronvall, Christian G Giske, Gunnar Kahlmeter
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  ABSTRACT: Antimicrobial susceptibility testing plays a key role in clinical microbiology. The disk diffusion test dates back to the 1940s and became standardised from the 1950s, with the International Collaborative Study (ICS) and National Committee for Clinical Laboratory Standards (NCCLS) as the two major standards. Interlaboratory variation of disk test results was recognised early but has never been dealt with in a satisfactory manner. The error-rate bounded method was described in 1974 and its role is discussed. Species-specific susceptibility interpretation was coined in 1980 for Proteus mirabilis and chloramphenicol. In the late 1970s, more extensive use of species-specific breakpoints was introduced in Lund (Sweden). At the same time, P. Mouton constructed species-specific regression lines and pointed out the difficulties with narrow ranges of minimal inhibitory concentration (MIC) values. A more general use of species-specific regression lines was made possible with single-strain regression analysis, using one well-defined strain tested in disk diffusion with a range of disk contents. This method made it possible to calibrate the disk test in an individual laboratory. Other methods to achieve such calibration are also described. A recent method, 'MIC-coloured zone diameter histogram-technique', has proven useful for the validation of species-specific interpretive breakpoints. The microbiological breakpoint proposed by Williams in 1990 has experienced a renaissance with the European Committee on Antimicrobial Susceptibility Testing (EUCAST) epidemiological cut-off value (ECOFF). MIC and zone diameter distributions with accompanying ECOFFs for species-antimicrobial combinations are published on the EUCAST website. A method for the reconstruction of wild-type zone diameter populations, namely normalised resistance interpretation, is described. This method can produce resistance figures that are truly comparable between laboratories.
  International journal of antimicrobial agents 06/2011; 38(4):281-90. · 3.03 Impact Factor
• Article: In vitro activity of CXA-101 plus tazobactam (CXA-201) against CTX-M-14- and CTX-M-15-producing Escherichia coli and Klebsiella pneumoniae.

  Emilia Titelman, Inga M Karlsson, Yigong Ge, Christian G Giske
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  ABSTRACT: CXA-101, a novel cephalosporin with good antipseudomonal activity, was evaluated against a consecutive and polyclonal collection of extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli (n = 149) and Klebsiella pneumoniae (n = 20), mainly CTX-M-15- (69%) or CTX-M-14 producing (22%). A total of 41% of the E. coli isolates belonged to the international clone O25b-ST131. Broth microdilution versus CXA-101, CXA-tazobactam 4 and 8 mg/L (CXA-201), ceftazidime-tazobactam (CAT), ceftazidime-clavulanate (CAC), piperacillin-tazobactam (TZP), amoxicillin-clavulanate (ACL), ampicillin-sulbactam (ASU), and other comparators was performed, using EUCAST methodology and breakpoints. Susceptibility to CXA-201 was 96% (tazobactam 8 mg/L, tentative breakpoint S ≤ 1 mg/L), CAT 93%, CAC 95%, ACL 24%, ASU 2%, TZP 58%, ciprofloxacin 25%, levofloxacin 30%, gentamicin 54%, tobramycin 34%, amikacin 90%, and tigecycline 98%. Ninety-four percent of the TZP-resistant and all ACL-resistant isolates were CXA-201 susceptible. CXA-201 has good in vitro activity against ESBL-producing Enterobacteriaceae and might be a future therapeutic option for infections caused by TZP- and ACL-resistant isolates.
  Diagnostic microbiology and infectious disease 05/2011; 70(1):137-41. · 2.45 Impact Factor
• Source

  Available from: PubMed Central

  Article: Population structure of Pseudomonas aeruginosa from five Mediterranean countries: evidence for frequent recombination and epidemic occurrence of CC235.

  Makaoui Maatallah, Jihane Cheriaa, Amina Backhrouf, Aina Iversen, Hajo Grundmann, Thuy Do, Philippe Lanotte, Maha Mastouri, Mohamed Salem Elghmati, Fernando Rojo, Snoussi Mejdi, Christian G Giske
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  ABSTRACT: Several studies in recent years have provided evidence that Pseudomonas aeruginosa has a non-clonal population structure punctuated by highly successful epidemic clones or clonal complexes. The role of recombination in the diversification of P. aeruginosa clones has been suggested, but not yet demonstrated using multi-locus sequence typing (MLST). Isolates of P. aeruginosa from five Mediterranean countries (n = 141) were subjected to pulsed-field gel electrophoresis (PFGE), serotyping and PCR targeting the virulence genes exoS and exoU. The occurrence of multi-resistance (≥ 3 antipseudomonal drugs) was analyzed with disk diffusion according to EUCAST. MLST was performed on a subset of strains (n = 110) most of them had a distinct PFGE variant. MLST data were analyzed with Bionumerics 6.0, using minimal spanning tree (MST) as well as eBURST. Measurement of clonality was assessed by the standardized index of association (I(A) (S)). Evidence of recombination was estimated by ClonalFrame as well as SplitsTree4.0. The MST analysis connected 70 sequence types, among which ST235 was by far the most common. ST235 was very frequently associated with the O11 serotype, and frequently displayed multi-resistance and the virulence genotype exoS⁻/exoU⁺. ClonalFrame linked several groups previously identified by eBURST and MST, and provided insight to the evolutionary events occurring in the population; the recombination/mutation ratio was found to be 8.4. A Neighbor-Net analysis based on the concatenated sequences revealed a complex network, providing evidence of frequent recombination. The index of association when all the strains were considered indicated a freely recombining population. P. aeruginosa isolates from the Mediterranean countries display an epidemic population structure, particularly dominated by ST235-O11, which has earlier also been coupled to the spread of ß-lactamases in many countries.
  PLoS ONE 01/2011; 6(10):e25617. · 4.09 Impact Factor
• Article: The DiversiLab system versus pulsed-field gel electrophoresis: characterisation of extended spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae.

  Alma Brolund, Sara Hæggman, Petra J Edquist, Lena Gezelius, Barbro Olsson-Liljequist, Karin Tegmark Wisell, Christian G Giske
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  ABSTRACT: Fast and reliable epidemiological typing methods for identifying outbreaks and epidemic strains of extended spectrum β-lactamase (ESBL) producing Enterobacteriaceae are urgently needed. The DiversiLab system (DL) has been proposed for these purposes. We compared DL to pulsed-field gel electrophoresis (PFGE) on a national collection of ESBL-producing Escherichia coli (n=258; of which 226 isolates were typeable with PFGE) and Klebsiella pneumoniae (n=48) isolated in 2007. For E. coli the Wallace coefficients showed that the probability of two isolates of the same DL type having the same PFGE type was only 19.8% and the probability of two isolates of the same PFGE type having the same DL type was 90.4%. For K. pneumoniae the Wallace coefficients showed that the probability of two isolates of the same DL type having the same PFGE type was 100% and the probability of two isolates of the same PFGE type having the same DL type was 79%, indicating that for this K. pneumoniae strain collection DL was slightly more discriminatory. Only four of 48 isolates had discordant results with the two methods. In E. coli 42% of the isolates were sequence type 131 and these isolates were related at >95% similarity with DL and at ≥60% similarity with PFGE. In summary, for E. coli DL performed well in identifying isolates related by PFGE, but overestimated the genetic relatedness in the studied collection. This indicates that DL could be a primary screening method for excluding unrelated isolates. Isolates shown to be related must be confirmed with a more discriminatory method. For K. pneumoniae, DL discriminated well but overestimated the diversity of the isolates compared to PFGE, assuming a risk of missing possible genetic relatedness.
  Journal of microbiological methods 11/2010; 83(2):224-30. · 2.43 Impact Factor
• Article: Development of a real-time SYBRGreen PCR assay for rapid detection of acquired AmpC in Enterobacteriaceae.

  Alma Brolund, Karin Tegmark Wisell, Petra J Edquist, Lisbeth Elfström, Mats Walder, Christian G Giske
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  ABSTRACT: Acquired AmpC enzymes, classified as miscellaneous extended-spectrum beta-lactamase (ESBL(M)) enzymes according to a recently proposed beta-lactamase classification, are increasing according to several publications. Simple and rapid methods for detection of ESBL(M) are needed for appropriate infection control. A gel-based multiplex PCR method for acquired bla(AmpC) detection and subtype classification has been available for several years. Here, we describe a modification of the protocol to suit real-time PCR platforms and to include novel genotypes. Clinical isolates with clavulanic acid non-reversible non-susceptibility to extended-spectrum cephalosporins were subjected to combination disk testing with cefoxitin +/- cloxacillin at Malmö University Hospital. Phenotypical AmpC production was defined as cloxacillin reversible cefoxitin resistance. In this study 51 phenotypical AmpC-producing isolates, were subjected to the acquired bla(AmpC) real-time PCR assay. The acquired blaAmpC positive isolates were further characterized by DNA sequencing of the acquired AmpC encoding gene, Pulsed-Field Gel Electrophoresis (PFGE) and PCR-based replicon typing. The real-time PCR assay was able to detect and sub-classify all acquired bla(AmpC) genes described to date. The assay can be performed in less than 3h, including pre-PCR preparations. Analysis of the isolate collection resulted in 18 of 51 phenotypical AmpC-producing isolates being positive in the acquired bla(AmpC) real-time multiplex PCR assay; 17 of subtype CIT and one DHA. Sequence analysis identified 16 isolates as blaCMY-2, one as blaCMY-16 and one as blaDHA-1. Detected plasmid replicon types were I1 and B/O. Two of the E. coli isolates were identical according to PFGE and the others were unrelated.
  Journal of microbiological methods 09/2010; 82(3):229-33. · 2.43 Impact Factor
• Source

  Available from: Sunil Maharjan

  Article: Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study.

  Karthikeyan K Kumarasamy, Mark A Toleman, Timothy R Walsh, Jay Bagaria, Fafhana Butt, Ravikumar Balakrishnan, Uma Chaudhary, Michel Doumith, Christian G Giske, Seema Irfan, [......], Jayanta B Sarma, Madhu Sharma, Elizabeth Sheridan, Mandayam A Thirunarayan, Jane Turton, Supriya Upadhyay, Marina Warner, William Welfare, David M Livermore, Neil Woodford
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  ABSTRACT: Gram-negative Enterobacteriaceae with resistance to carbapenem conferred by New Delhi metallo-beta-lactamase 1 (NDM-1) are potentially a major global health problem. We investigated the prevalence of NDM-1, in multidrug-resistant Enterobacteriaceae in India, Pakistan, and the UK. Enterobacteriaceae isolates were studied from two major centres in India--Chennai (south India), Haryana (north India)--and those referred to the UK's national reference laboratory. Antibiotic susceptibilities were assessed, and the presence of the carbapenem resistance gene bla(NDM-1) was established by PCR. Isolates were typed by pulsed-field gel electrophoresis of XbaI-restricted genomic DNA. Plasmids were analysed by S1 nuclease digestion and PCR typing. Case data for UK patients were reviewed for evidence of travel and recent admission to hospitals in India or Pakistan. We identified 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among Escherichia coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics except to tigecycline and colistin. K pneumoniae isolates from Haryana were clonal but NDM-1 producers from the UK and Chennai were clonally diverse. Most isolates carried the NDM-1 gene on plasmids: those from UK and Chennai were readily transferable whereas those from Haryana were not conjugative. Many of the UK NDM-1 positive patients had travelled to India or Pakistan within the past year, or had links with these countries. The potential of NDM-1 to be a worldwide public health problem is great, and co-ordinated international surveillance is needed.
  The Lancet Infectious Diseases 09/2010; 10(9):597-602. · 17.39 Impact Factor
• Article: Outbreak of CTX-M-15-producing Klebsiella pneumoniae of sequence type 199 in a Latvian teaching hospital.

  Uga Dumpis, Aina Iversen, Arta Balode, Māra Saule, Edvīns Miklasevics, Christian G Giske
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  ABSTRACT: Previous studies on the epidemiology of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Latvia are lacking. ESBL-producing Klebsiella pneumoniae (n = 32) were subjected to pulsed-field gel electrophoresis (PFGE) and selected isolates to multi-locus sequence typing (MLST). Species identification and susceptibility testing were performed using VITEK2, and sequencing of bla(CTX-M) was performed in selected isolates. PFGE revealed one major clone (n = 23), with most of the isolates derived from the ICU. The clone harboured bla(CTX-M-15), was sequence type 199 and comprised two ertapenem non-susceptible isolates. This is the first report of an ESBL outbreak in Latvia, and calls for increased epidemiological typing of ESBL-producing Enterobacteriaceae, as well as improved infection control routines.
  Apmis 09/2010; 118(9):713-6. · 1.99 Impact Factor
• Article: Etiology of community-acquired pneumonia: increased microbiological yield with new diagnostic methods.

  Niclas Johansson, Mats Kalin, Annika Tiveljung-Lindell, Christian G Giske, Jonas Hedlund
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  ABSTRACT: The microbial etiology of community-acquired pneumonia (CAP) is still not well characterized. During the past few years, polymerase chain reaction (PCR)-based methods have been developed for many pathogens causing respiratory tract infections. The aim of this study was to determine the etiology of CAP among adults-especially the occurrence of mixed infections among patients with CAP-by implementing a new diagnostic PCR platform combined with conventional methods. Adults admitted to Karolinska University Hospital were studied prospectively during a 12-month period. Microbiological testing methods included culture from blood, sputum, and nasopharyngeal secretion samples; sputum samples analyzed by real-time quantitative PCR for Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis; nasopharyngeal specimens analyzed by use of PCR; serological testing for Mycoplasma pneumoniae, Chlamydophila pneumoniae, and viruses common in the respiratory tract; and urine antigen assays for detection of pneumococcal and Legionella pneumophila antigens. A microbial etiology could be identified for 67% of the patients (n = 124). For patients with complete sampling, a microbiological agent was identified for 89% of the cases. The most frequently detected pathogens were S. pneumoniae (70 patients [38%]) and respiratory virus (53 patients [29%]). Two or more pathogens were present in 43 (35%) of 124 cases with a determined etiology. By supplementing traditional diagnostic methods with new PCR-based methods, a high microbial yield was achieved. This was especially evident for patients with complete sampling. Mixed infections were frequent (most commonly S. pneumoniae together with a respiratory virus).
  Clinical Infectious Diseases 12/2009; 50(2):202-9. · 9.15 Impact Factor