Low‐level resistance and clonal diversity of Pseudomonas aeruginosa among chronically colonized cystic fibrosis patients

A prospective study was conducted in Brazil to evaluate antimicrobial resistance patterns and molecular epidemiology of Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients with chronic lung infection. All isolates were obtained between May 2009 and June 2010 from 75 patients seen in four reference centers in Brazil: HCPA (20 patients) and HEOM (15 patients), located in southern and northeastern Brazil, respectively; IFF (20 patients) and HUPE (20 patients), both in southwestern Brazil. Antimicrobial susceptibility testing, PCR for detection of carpapenemases, and pulsed‐field gel electrophoresis (PFGE) were performed in 274 isolates. A total of 224 PFGE types were identified and no clones were found circulating among the centers or within the same center. Despite the chronic infection, most patients were colonized by intermittent clones. Only three patients (4%) maintained the same clone during the study. The resistance rates were lower than 30% for the majority of antimicrobials tested in all centers and only 17% of isolates were multiresistant. Isolates (n = 54) with reduced susceptibility to imipenem and/or meropenem presented negative results for bla_SPM‐1, bla_IMP?1, bla_VIM, and bla_KPCgenes. Our results indicate an unexpected low level of antimicrobial resistance and a high genotypic diversity among P. aeruginosa from Brazilian chronic CF patients.     

Epidemiological typing of clinical isolates of <Emphasis Type="Italic">Achromobacter xylosoxidans</Emphasis>: comparison of phenotypic and genotypic methods

The purpose of this paper is to evaluate the utility of different typing methods for Achromobacter xylosoxidans clinical isolates. Ninety-two blood culture isolates of A. xylosoxidans subsp. xylosoxidans were collected over a 25-month period. The typeability, discriminatory power and reproducibility of commonly used phenotypic and genotypic methods, such as resistotyping, plasmid profiling, whole-cell protein fingerprinting, random amplification of polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE), were compared. All 92 isolates were typeable by all of the methods used, with comparable reproducibility. PFGE showed the highest discriminatory power (98.9%), but whole-cell protein profiling showed better correlation with epidemiological data without significant loss in discriminatory power (94%). Whole-cell protein profiling is a reliable epidemiological tool for the analysis of A. xylosoxidans; PFGE is the most discriminatory.     

Achromobacter xylosoxidans respiratory tract infection in cystic fibrosis patients

The aims of this study were to evaluate the frequency of Achromobacter xylosoxidans infection in a cohort of cystic fibrosis patients, to investigate antimicrobial sensitivity, to establish possible clonal likeness among strains, and to address the clinical impact of this infection or colonization on the general outcome of these patients. The study was undertaken between January 2004 and December 2008 on 300 patients receiving care at the Regional Cystic Fibrosis Center of the Naples University “Federico II”. Sputum samples were checked for bacterial identification. For DNA fingerprinting, pulsed-field gel electrophoresis (PFGE) was carried out. Fifty-three patients (17.6%) had at least one positive culture for A. xylosoxidans; of these, 6/53 (11.3%) patients were defined as chronically infected and all were co-colonized by Pseudomonas aeruginosa. Of the patients, 18.8% persistently carried multidrug-resistant isolates. Macrorestriction analysis showed the presence of seven major clusters. DNA fingerprinting also showed a genetic relationship among strains isolated from the same patients at different times. The results of DNA fingerprinting indicate evidence of bacterial clonal likeness among the enrolled infected patients. We found no significant differences in the forced expiratory volume in 1 s (FEV₁) and body mass index (BMI) when comparing the case group of A. xylosoxidans chronically infected patients with the control group of P. aeruginosa chronically infected patients.     

Outbreak of long-term intravascular catheter-related bacteremia due to Achromobacter xylosoxidans subspecies xylosoxidans in a hemodialysis unit

Achromobacter xylosoxidans is a rare cause of bacteremia. Over a 2-week period, A. xylosoxidans subsp. xylosoxidans was isolated from blood cultures of four hemodialysis patients with long-term intravascular catheters. A culture from one atomizer that contained diluted 2.5% chlorhexidine, which had been used to disinfect the skin, yielded A. xylosoxidans subsp. xylosoxidans. No further cases were diagnosed once the use of this atomizer was discontinued. Five outbreak-related strains from the four patients and the atomizer were tested by pulsed-field gel electrophoresis (PFGE) under XbaI restriction. The isolates from the first three patients and the atomizer had identical PFGE patterns, confirming the atomizer as the source of the outbreak. The strain isolated from the fourth patient had six more bands than the outbreak strain and was considered possibly related to the outbreak strain. All patients were treated with intravenous levofloxacin. The catheter was removed in only one patient. The three patients in whom the catheter was left in place were also treated with antibiotic lock therapy with levofloxacin. All four patients were cured. This is believed to be the first reported outbreak of central venous catheter-related bacteremia due to A. xylosoxidans and the second reported outbreak with this organism associated with chlorhexidine atomizers. The use of diluted chlorhexidine via atomizers can be dangerous for the care of venous catheters and should be called into question. Patients with long-term intravascular catheter-related bacteremia due to this organism can be treated successfully with systemic antimicrobial therapy in addition to antibiotic lock therapy without catheter removal.     

Persistent Colonization of Nine Cystic Fibrosis Patients with an<Emphasis Type="Italic"> Achromobacter</Emphasis> (<Emphasis Type="Italic">Alcaligenes</Emphasis>)<Emphasis Type="Italic"> xylosoxidans</Emphasis> Clone

The present study was conducted to investigate the increasing incidence of Achromobacter (previously Alcaligenes) xylosoxidans isolates being recovered from sputum samples of cystic fibrosis patients at a cystic fibrosis department for adults in Athens, Greece. During the 1-year study period, a total of 34 isolates were detected persistently in 9 of 71 cystic fibrosis patients. The isolates exhibited resistance to multiple antimicrobial agents. Isolates that were recovered repeatedly from each patient exhibited identical macrorestriction profiles with pulsed-field gel electrophoresis, indicating that the same strain persisted in the lungs of these patients. Isolates from five of the patients were genetically related, suggesting a common-source outbreak of Achromobacter xylosoxidans colonization or infection.     

Genotyping of Pseudomonas aeruginosa isolates from lung transplant recipients and aquatic environment–detected in‐hospital transmission

Lung infection with Pseudomonas aeruginosa is common in lung transplant recipients and may lead to severe complications. Bacteriological surveillance aims to detect transmission of microbes between hospital environment and patients. We sought to determine whether genotyping of P. aeruginosa isolates could improve identifications of pathways of infection. From 2004 to 2009, we performed genotyping with multiple‐locus variable number of tandem repeats analysis (MLVA) and pulsed‐field gel electrophoresis (PFGE) of P. aeruginosa isolates cultured from lung transplant recipients at Sahlgrenska University Hospital, Gothenburg. During a small outbreak in 2008, cultivation and genotyping of isolates from sink and drains samples from the hospital ward were performed. Pseudomona aeruginosa from 11/18 patients were genotyped to unique strains. The remaining seven patients were carriers of a P. aeruginosa strain of cluster A genotype. Pseudomona aeruginosa was isolated in 4/8 water samples, typed by MLVA also as cluster A genotype and confirmed by PFGE to be similar or identical to the isolates from four transplanted patients. In conclusion, genotyping of isolates revealed a clonal relationship between patient and water isolates, indicating in‐hospital transmission of P. aeruginosa. We suggest genotyping with MLVA for rapid routine surveillance, with the PFGE method used for extended, confirmatory analyses.     

Staphylococcus aureus as source of catheter‐related bloodstream infection evaluated by PFGE and rep‐PCR typing in a Brazilian hospital

Staphylococci are a common cause of catheter‐related bloodstream infection (CR‐BSI), and epidemiological typing is an important tool for effective infection control. This study evaluated by PFGE and rep‐PCR whether Staphylococcus aureus strains isolated from skin and catheter tips were related to specimens isolated from blood. A prospective observational study, carried out in a clinical surgical ward at a Brazilian hospital between September 2000 and November 2002, investigated non‐tunneled central venous catheters from 179 patients. S. aureus isolates were mainly obtained from blood (41.4%), while coagulase‐negative staphylococci strains were more often isolated from the skin at the catheter insertion site (49.7%) and from the catheter tip (57.5%). Among the 21 strains isolated from 9 patients at 2 or 3 sites simultaneously, 9 were methicillin‐resistant S. aureus (MRSA) and 12 were methicillin‐susceptible S. aureus (MSSA). Seven patients harbored the same S. aureus strain isolated from the skin, blood and/or catheter tip cultures. MRSA isolates belonged to one PFGE pattern (type A‐ subtypes A₁, A₂ and A₃), and to two rep‐PCR patterns (a and b). MSSA isolates were distinguished in five PFGE (B to F) and in three rep‐PCR (c, d and e) patterns. Both PFGE and rep‐PCR methods indicated that the skin at the catheter insertion site was the origin of CR‐BSI caused by S. aureus.     

Investigation of Acinetobacter baumannii resistance to carbapenems in Marseille hospitals,south of France: a transition from an epidemic to an endemic situation

Carbapenem‐resistant Acinetobacter baumannii infections are a worldwide endemic nosocomial threat. Between December 2010 and April 2011, an increase of carbapenem‐resistant A. baumannii infections occurred in several Marseille University Hospitals. The aim of this study was to investigate the increase of carbapenem‐resistant A. baumannii infections and to characterize the mechanisms of carbapenem resistance. The increase was detected by a homemade computer surveillance program, known as EPIMIC, that monitors antibiotic resistance profiles on a weekly basis. During this period, positive samples of carbapenem‐resistant A. baumannii were retrieved from patients hospitalized in different units. Genotyping of the isolates was performed using pulsed‐field gel electrophoresis (PFGE) and multi‐locus sequence typing (MLST), and carbapenemase gene analyses were performed to detect the presence of carbapenemases and to determine the relationships of the isolates. Carbapenem‐resistant A. baumannii were isolated in a total of 11 patients who were hospitalized in different hospitals units. We identified the presence of the bla_OXA23‐like carbapenemase‐encoding gene in all of the isolates and found four major PFGE groups and different MLST groups. These results demonstrate a current evolution in the A. baumannii epidemiology in Marseille with a switch from an epidemic situation to an endemic situation and with several circulating clones.     

Evaluation of colistin susceptibility in multidrug-resistant clinical isolates from cystic fibrosis, France

The emergence of multidrug-resistant (MDR) bacteria in cystic fibrosis (CF) patients has led to the use of colistin drug and the emergence of colistin-resistant Gram-negative bacteria. The aim of this study was to compare the disk diffusion and Etest methods for colistin susceptibility testing on MDR bacteria associated with CF from Marseille, France. Forty-nine MDR clinical isolates (27 Stenotrophomonas maltophilia, 22 Achromobacter xylosoxidans) were used in this study. Disk diffusion and Etest assays were used to assess the reliability of these two techniques. For S. maltophilia, 25 out of 27 isolates had low minimum inhibitory concentrations (MICs, 0.125–0.75 mg/L), whereas two isolates displayed high MICs (32 mg/L). Similarly, 19 out of 22 A. xylosoxidans isolates had low MICs (0.75–3.0 mg/L), whereas three isolates had high MICs (32–256 mg/L). The diameters of zone inhibition with a 50-μg colistin disk displayed a good correlation with the MICs obtained by the Etest. Susceptible and resistant strains were eventually separated using a disk diffusion assay at a cut-off of ≤12 mm for a 50-μg disk. Colistin displayed excellent activity against S. maltophilia and A. xylosoxidans and the disk diffusion assay could be confidently used to determine the susceptibility to colistin for MDR Gram-negative bacteria in the context of CF.     

Variation of the antimicrobial susceptibility profiles of <Emphasis Type="Italic">Burkholderia cepacia</Emphasis> complex clonal isolates obtained from chronically infected cystic fibrosis patients: a five-year survey in the major Portuguese treatment center

The treatment of cystic fibrosis (CF) patients chronically infected with Burkholderia cepacia complex (Bcc) bacteria requires extensive and aggressive antibiotics therapy, exposing these bacteria to prolonged antibiotics-selective pressure. In the present study, we have compared the susceptibility patterns to 13 antimicrobials of 94 Bcc isolates obtained from 15 Portuguese CF patients in the course of chronic infection during a five-year survey. These isolates were previously genotyped and represent 11 different strains of the species B. cenocepacia (subgroups A and B), B. cepacia, B. multivorans, and B. stabilis. The results are consistent with the notion that CF Bcc isolates are resistant to the most clinically relevant antimicrobials and suggest an uneven distribution of resistance rates among the different species, with B. cenocepacia subgroup A isolates being the most resistant. Phenotypic variants exhibiting differences in the antimicrobial susceptibility patterns were obtained from the sputum samples of clinically deteriorated CF patients during chronic lung infection. The isolation of resistant variants coincided with periods of pulmonary exacerbation and antibiotics therapy.     

Clinical isolates of Staphylococcus aureus from the Arkhangelsk region,Russia: antimicrobial susceptibility,molecular epidemiology,and distribution of Panton‐Valentine leucocidin genes

A total of 91 consecutive clinical isolates of Staphylococcus aureus were collected at the Regional Hospital of Arkhangelsk, Russia, from May to December 2004, and examined for antimicrobial susceptibility, methicillin resistance and presence of Panton‐Valentine leucocidin (PVL) genes. Epidemiological typing was performed by pulsed‐field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Methicillin‐resistant S. aureus (MRSA) isolates were examined by staphylococcal cassette chromosome mec (SCCmec) typing. High‐to‐moderate rates of resistance to penicillin (β‐lactamase production; 93%), tetracycline (40%), erythromycin and clindamycin (32%) were observed. Forty out of ninety‐one (44%) isolates were positive for PVL genes. Thirty‐six (40%) PVL‐positive methicillin‐susceptible S. aureus (MSSA) strains were shown by PFGE and MLST typing (ST121, ST681, ST837) to be part of a nosocomial outbreak caused by clonal complex (CC) 121. PFGE, MLST and SCCmec typing revealed three MRSA clones. Sequence type (ST) 239‐III (n=11), ST1097‐III (n=1) and ST8‐IV (n=3) belong to CC8 of epidemic multiresistant MRSA, whereas ST426‐MRSA‐IV/CC395 (n=1) has not been reported previously. All MRSA strains were PVL negative. The overall results underline the necessity of microbiological sampling, antimicrobial susceptibility testing, and epidemiological typing as a rational basis for antimicrobial treatment of S. aureus infections, and infection control measures to limit the spread of multiresistant MRSA and epidemic MSSA clones.     

Detection of invasive protein profile of Streptococcus pyogenes M1 isolates from pharyngitis patients

Hasegawa T, Okamoto A, Kamimura T, Tatsuno I, Hashikawa S‐N, Yabutani M, Matsumoto M, Yamada K, Isaka M, Minami M, Ohta M. Detection of invasive protein profile of Streptococcus pyogenes M1 isolates from pharyngitis patients. APMIS 2010; 118: 167–78. Streptococcal toxic shock syndrome (STSS) is a re‐emerging infectious disease in Japan and many other developed countries. Epidemiological studies have revealed that the M1 serotype of Streptococcus pyogenes is the most dominant causative isolate of STSS. Recent characterization of M1 isolates revealed that the mutation of covS, one of the two‐component regulatory systems, plays an important role in STSS by altering protein expression. We analyzed the M1 S. pyogenes clinical isolates before or after 1990 in Japan, using two‐dimensional gel electrophoresis (2‐DE) and pulsed‐field gel electrophoresis (PFGE). PFGE profiles were different between the isolates before and after 1990. Markedly different profiles among isolates after 1990 from STSS and pharyngitis patients were detected. Sequence analysis of two‐component regulatory systems showed that covS mutations were detected not only in STSS but also in three pharyngitis isolates, in which proteins from the culture supernatant displayed the invasive type. The mutated CovS detected in the pharyngitis isolates had impaired function on the production of streptococcal pyrogenic exotoxin B (SpeB) analyzed by 2‐DE. These results suggest that several covS mutations that lead to the malfunction of the CovS protein occurred even in pharyngeal infection.     

Near absence of methicillin-resistance and pronounced genetic diversity among Staphylococcus epidermidis isolated from healthy persons in northern Sweden

Widerström M, Wiström J, Ek E, Edebro H, Monsen T. Near absence of methicillin‐resistance and pronounced genetic diversity among Staphylococcus epidermidis isolated from healthy persons in northern Sweden. APMIS 2011; 119: 505–12. The main aim of this study was to examine if hospital‐associated clones of multidrug‐resistant Staphylococcus epidermidis (MDRSE), commonly identified in hospitals in our region, also are spread among healthy persons in the community. A total of 124 isolates of S. epidermidis sampled from subjects attending a Travel health clinic, Umeå, Sweden during 2008 were examined with antibiotic susceptibility testing and pulsed‐field gel electrophoresis (PFGE) analysis. Resistance to methicillin or any antibiotic was detected in 2 and 26 of the isolates, respectively. PFGE analysis showed an extensive genetic diversity with 86 different PFGE types, 62 of which were singletons. No isolates belonged to the previously described hospital‐associated MDRSE genotypes, indicating that MDRSE by large are confined to the hospital setting in our region. In conclusion, community‐associated isolates of S. epidermidis showed a low level of methicillin‐resistance and were genetically extremely diverse with no predominating genotype.     

Molecular Characterization of Achromobacter Isolates from Cystic Fibrosis and Non-Cystic Fibrosis Patients in Madrid,Spain

Multilocus sequence typing and nrdA sequence analysis identified 6 different species or genogroups and 13 sequence types (STs) among 15 Achromobacter isolates from cystic fibrosis (CF) patients and 7 species or genogroups and 11 STs among 11 isolates from non-CF patients. Achromobacter xylosoxidans was the most frequently isolated species among CF patients.     

Screening for vancomycin‐resistant enterococci: results of a survey in Stockholm

Fang H, Nord CE, Ullberg M. Screening for vancomycin‐resistant enterococci: results of a survey in Stockholm. APMIS 2010; 118: 413–7. Vancomycin‐resistant enterococci (VRE) are emerging in Stockholm hospitals. To rapidly screen for VRE from stool and rectal swab samples, a detection assay combining broth enrichment and real‐time PCR was set up. From September to December 2008, 6914 samples were screened for VRE using the broth‐PCR combined assay. Of them, 5463 samples were reported as negative the day after sampling. Among the 6914 samples, 47 was screened as vanA probable and 44 of them were confirmed as VRE; 1314 samples was screened as vanB probable and 93 of them were confirmed as VRE. The 44 vanA‐type VRE isolates, detected from 31 patients, were clustered into four genetic types by pulsed‐field gel electrophoresis (PFGE). The same PFGE type was observed in multiple isolates recovered from the same patient with vanA VRE. The 93 vanB‐type VRE isolates were detected from 60 patients, 59 of them harboring VRE with PFGE type 1. One patient with vanB VRE had two isolates of distinct PFGE types (types 1 and 5). PFGE type 1 and PFGE type 2 were predominant clones in vanB and vanA strains, respectively, represented by 98.3% (59/60) of patients with vanB VRE and 77.4% (24/31) of patients with vanA VRE.     

Six-year molecular analysis of Burkholderia cepacia complex isolates among cystic fibrosis patients at a referral center for lung transplantation

Over a 6-year period, Burkholderia cepacia complex species were isolated from cystic fibrosis (CF) patients receiving care at The University of North Carolina Hospitals (clinic CF patients) and from those referred from other treatment centers. Fifty-six isolates collected from 30 referred patients and 26 clinic CF patients were characterized by pulsed-field gel electrophoresis (PFGE) and were assayed by PCR to detect the cable pilin gene, cblA. PFGE results indicated that six separate clusters (clusters A to F) were present among the 56 isolates and that three clusters (clusters A, B, and E) consisted only of isolates from referred patients infected with B. cepacia complex isolates prior to referral. However, one cluster (cluster C) consisted of isolates from four CF patients, and hospital records indicate that this cluster began with an isolate that came from a referred patient and that spread to three clinic CF patients. Cluster D consisted of two isolates from clinic CF patients, and hospitalization records are consistent with nosocomial, patient-to-patient spread. cblA was present in only 4 of the 56 isolates and included isolates in cluster E from the referred patients. Our results indicate a lack of spread of a previously characterized, transmissible clone from referred patients to our clinic CF population. Only two instances of nosocomial, patient-to-patient spread could be documented over the 6-year period. An additional spread of an isolate (cluster F) from a referred patient to a clinic patient could not be documented as nosocomial and may have been the result of spread in a nonhospitalized setting. The majority (36 of 56) of our B. cepacia complex-infected CF patients harbor isolates with unique genotypes, indicating that a diversity of sources account for infection. These data suggest that CF patients infected with B. cepacia complex and referred for lung transplantation evaluation were not a major source of B. cepacia complex strains that infected our resident CF clinic population.     

Achromobacter xylosoxidans Genomic Characterization and Correlation of Randomly Amplified Polymorphic DNA Profiles of Cystic Fibrosis Patients

Achromobacter xylosoxidans is an emerging pathogen increasingly being isolated from respiratory samples of cystic fibrosis (CF) patients. Its role and clinical significance in lung pathogenesis have not yet been clarified. The aim of the present study was to genetically characterize A. xylosoxidans strains isolated from CF patients by use of randomly amplified polymorphic DNA (RAPD) profiles and to look for a possible correlation between RAPD profiles and the patients'' clinical features, such as their spirometry values, the presence of concomitant chronic bacterial flora at the time of isolation, and the persistent or intermittent presence of A. xylosoxidans strains. A set of 106 strains of A. xylosoxidans were typed by RAPD analysis, and their profiles were analyzed by agglomerative hierarchical classification (AHC) and associated with the patient characteristics mentioned above by factorial discriminant analysis (FDA). The overall results obtained in this study showed that (i) there is a marked genetic relationship between strains isolated from the same patients at different times, (ii) characteristic RAPD profiles are associated with different predicted classes for forced expiratory volume in 1 s (FEV1%), (iii) some characteristic RAPD profiles are associated with different concomitant chronic flora (CCF) profiles, and (iv) there is a significant division of RAPD profiles into “persistent strains” and “intermittent strains” of A. xylosoxidans. These findings seem to imply that the lung habitats found in CF patients are capable of shaping and selecting the colonizing bacterial flora, as seems to be the case for the A. xylosoxidans strains studied.Cystic fibrosis (CF) is the most common lethal genetic disease, causing a chronic infection of the respiratory tract, which in turn leads to progressive respiratory deficiency (6, 15). Pseudomonas aeruginosa is the most frequently found Gram-negative pathogen in the sputa of patients with CF, while Staphylococcus aureus is the most frequently found Gram-positive one. Recently, new pathogens have also emerged, such as Burkholderia cepacia complex, Stenotrophomonas maltophilia, and Achromobacter xylosoxidans (3, 9, 18, 19, 20, 24). Although the clinical significance of A. xylosoxidans is not yet clear, it is increasingly being isolated from the sputum cultures of CF patients. Tan et al. (22) found that 2.3% of CF patients had at least 3 positive cultures for A. xylosoxidans during a 6-month period. The U.S. Cystic Fibrosis Foundation''s National Patient Registry reported an increase of 4.5%, from 1995 to 2002 (1, 2), in the frequency of isolation of this microorganism from CF patients. Recently, A. xylosoxidans has been considered a nosocomial pathogen, particularly in immunocompromised patients, causing a variety of infections, including bacteremia, meningitis, pneumonia, and peritonitis (8, 23, 25). Achromobacter spp. are aerobic, nonfermentative, Gram-negative bacilli (5, 7, 21) that are frequently misidentified by routine laboratory tests, thus seriously compromising control measures related to epidemiology studies. These microorganisms are often highly resistant to various antibiotics, including β-lactams, quinolones, aminoglycosides, and carbapenems, all commonly used for the management of lung infection in CF patients.Considering the importance of bacterial lung infections in CF patients, our goals were (i) to assess the genetic relationships among isolated A. xylosoxidans strains by randomly amplified polymorphic DNA (RAPD) analysis and (ii) to use multivariate analysis techniques to look for possible correlations between A. xylosoxidans RAPD profiles and patients'' clinical features (predicted classes for forced expiratory volume in 1 s [FEV1%], presence of concomitant chronic flora [CCF] during the isolation step, and persistent or intermittent presence of A. xylosoxidans). The study was conceived in order to give a picture of adaptive changes of A. xylosoxidans during lung infection in patients with CF and to improve our knowledge about this emerging pathogenic species, highlighting its potential role in CF disease.     

Molecular epidemiology of Mycobacterium abscessus, with focus on cystic fibrosis

Mycobacterium abscessus has been isolated increasingly often from the respiratory tracts of cystic fibrosis (CF) patients. It is not known whether these organisms are transmitted from person to person or acquired from environmental sources. Here, colony morphology and pulsed-field gel electrophoresis (PFGE) pattern were examined for 71 isolates of M. abscessus derived from 14 CF patients, three non-CF patients with chronic respiratory M. abscessus infection or colonization, one patient with mastoiditis, and four patients with infected wounds, as well as for six isolates identified as environmental contaminants in various clinical specimens. Contaminants and wound isolates mainly exhibited smooth colony morphology, while a rough colony phenotype was significantly associated with chronic airway colonization (P=0.014). Rough strains may exhibit increased airway-colonizing capacity, the cause of which remains to be determined. Examination by PFGE of consecutive isolates from the same patient showed that they all represented a single strain, even in cases where both smooth and rough isolates were present. When PFGE patterns were compared, it was shown that 24 patients had unique strains, while four patients harbored strains indistinguishable by PFGE. Two of these were siblings with CF. The other two patients, one of whom had CF, had not had contact with each other or with the siblings. Our results show that most patients colonized by M. abscessus in the airways have unique strains, indicating that these strains derive from the environment and that patient-to-patient transmission rarely occurs.     

Comparison of three molecular techniques for typing Pseudomonas aeruginosa isolates in sputum samples from patients with cystic fibrosis

Monitoring the emergence and transmission of Pseudomonas aeruginosa strains among cystic fibrosis (CF) patients is important for infection control in CF centers internationally. A recently developed multilocus sequence typing (MLST) scheme is used for epidemiologic analyses of P. aeruginosa outbreaks; however, little is known about its suitability for isolates from CF patients compared with that of pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). As part of a prevalence study of P. aeruginosa strains in Australian CF clinics, we compared the discriminatory power and concordance of ERIC-PCR, PFGE, and MLST among 93 CF sputum and 11 control P. aeruginosa isolates. PFGE and MLST analyses were also performed on 30 paired isolates collected 85 to 354 days apart from 30 patients attending two CF centers separated by 3,600 kilometers in order to detect within-host evolution. Each of the three methods displayed high levels of concordance and discrimination; however, overall lower discrimination was seen with ERIC-PCR than with MLST and PFGE. Analysis of the 50 ERIC-PCR types yielded 54 PFGE types, which were related by ≤ 6 band differences, and 59 sequence types, which were classified into 7 BURST groups and 42 singletons. MLST also proved useful for detecting novel and known strains and for inferring relatedness among unique PFGE types. However, 47% of the paired isolates produced PFGE patterns that within 1 year differed by one to five bands, whereas with MLST all paired isolates remained identical. MLST thus represents a categorical analysis tool with resolving power similar to that of PFGE for typing P. aeruginosa. Its focus on highly conserved housekeeping genes is particularly suited for long-term clinical monitoring and detecting novel strains.     

Outbreak of CTX‐M‐15‐producing Klebsiella pneumoniae of sequence type 199 in a Latvian teaching hospital

Dumpis U, Iversen A, Balode A, Saule M, Mikla?evi?s E, Giske CG. Outbreak of CTX‐M‐15‐producing Klebsiella pneumoniae of sequence type 199 in a Latvian teaching hospital. APMIS 2010; 118: 713–6. Previous studies on the epidemiology of extended‐spectrum β‐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.