RESUMEN
Capsular type K54 of Klebsiella pneumoniae is associated with hypervirulence and we sought to discover the basis for this among isolates submitted to the UK reference laboratory between 2012 and 2017. Isolates were typed by variable number tandem repeat analysis, and capsular type and virulence elements sought by PCR. The most prevalent type found (15/31 isolates) corresponded to clonal group (CG) 29 and included five representatives carrying rmpA, rmpA2 (regulators of mucoid phenotype), iutA and iroD (from the aerobactin and salmochelin siderophore clusters) associated with virulence plasmids. These included isolate KpvK54, recovered from pus. The remaining isolates did not carry a virulence plasmid. We also noted 11 further related isolates, including NCTC 9159, not of capsular type K54, but nevertheless sometimes associated with sepsis and abscesses. Whole-genome sequencing showed that KpvK54 carried a large virulence plasmid and an ICEKp3-like structure carrying the yersiniabactin cluster, absent in NCTC 9159. Comparative chromosomal analysis with an additional four genomes showed that KpvK54 shared further genes with K1-ST23 hypervirulent isolates, and with LS358, a K54-ST29 isolate from liver abscess puncture fluid. While CG29 isolates displayed varying degrees of virulence, some, especially those with the virulence plasmid (all K54), were clearly associated with hypervirulence.
Asunto(s)
Infecciones por Klebsiella/epidemiología , Klebsiella pneumoniae/fisiología , Klebsiella pneumoniae/patogenicidad , Plásmidos/fisiología , Cápsulas Bacterianas/fisiología , Inglaterra/epidemiología , Infecciones por Klebsiella/microbiología , Fenotipo , Reacción en Cadena de la Polimerasa , Prevalencia , VirulenciaRESUMEN
This study aimed to determine prevalence of Ralstonia spp. in cystic fibrosis patients, look for any evidence of cross infection and to describe clinical outcomes for patients infected by Ralstonia spp. Prevalence of Ralstonia spp. was calculated annually from 2008 to 2016. Pulsed-field gel electrophoresis was performed on ⩾1 sample from patients with an isolation of Ralstonia spp. between 2008 and 2016. A prospective, longitudinal observational study of adult patients was performed with 12 months follow-up from recruitment. Prevalence of Ralstonia spp. rose from 0·6% in 2008 to 2·4% in 2016. In total 12 out of 14 (86%) patients with ⩾1 isolation of Ralstonia spp. developed chronic infection. A pair and a group of three unrelated patients with epidemiological connections shared strains of Ralstonia mannitolilytica. Lung function of Ralstonia spp. infected patients was moderately to severely impaired. Prevalence of Ralstonia spp. is low but increasing. The risk of a patient developing chronic Ralstonia spp. infection following first acquisition is high and cross-infection may be possible. Whether Ralstonia spp. infection causes increased pulmonary exacerbation frequency and lung function decline needs to be evaluated in larger prospective studies.
Asunto(s)
Infección Hospitalaria/epidemiología , Fibrosis Quística/complicaciones , Fibrosis Quística/epidemiología , Infecciones por Bacterias Gramnegativas/complicaciones , Infecciones por Bacterias Gramnegativas/epidemiología , Ralstonia/aislamiento & purificación , Adolescente , Adulto , Comorbilidad , Infección Hospitalaria/microbiología , Fibrosis Quística/terapia , Electroforesis en Gel de Campo Pulsado , Inglaterra/epidemiología , Femenino , Infecciones por Bacterias Gramnegativas/microbiología , Humanos , Estudios Longitudinales , Masculino , Prevalencia , Estudios Prospectivos , Ralstonia/clasificación , Riesgo , Adulto JovenRESUMEN
OBJECTIVES: The objectives of this study were: (i) to describe an outbreak of multidrug-resistant Klebsiella pneumoniae in our population; (ii) to identify the potential source of this outbreak by examining antibiotic resistance trends in urocultures; (iii) to evaluate the contribution of this outbreak to resistance patterns over time in the two commonest Gram-negative blood culture isolates, namely K. pneumoniae and Escherichia coli; and (iv) to assess risk factors for multidrug resistance and the impact of this resistance on mortality and length of stay. METHODS: We searched Microbiology and Patient Administration Service databases retrospectively and describe resistance trends in E. coli and K. pneumoniae bloodstream infections (BSIs) in Oxfordshire, UK, over an 11 year period. RESULTS: An outbreak of a multidrug-resistant, CTX-M-15 extended-spectrum ß-lactamase (ESBL)-producing K. pneumoniae clone was identified and shown by multilocus sequence typing to belong to a novel sequence type designated ST490. This was associated with a sporadic change in resistance rates in K. pneumoniae BSIs with rates of multidrug resistance (defined as resistance to three or more antibiotic classes) reaching 40%. A case-control study showed prior antibiotic exposure as a risk factor for infection with this organism. During the same time period, rates of ESBL-producing Klebsiella spp. isolated from urocultures increased from 0.5% to almost 6%. By contrast, the rate of multidrug resistance in E. coli rose more steadily from 0% in 2000 to 10% in 2010. CONCLUSIONS: Changes in resistance rates may be associated with outbreaks of resistant clones in K. pneumoniae. Changing resistance patterns may affect important health economic issues such as length of stay.
Asunto(s)
Infecciones por Escherichia coli/sangre , Infecciones por Escherichia coli/microbiología , Infecciones por Klebsiella/sangre , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/enzimología , beta-Lactamasas/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Cuidados Críticos , Infección Hospitalaria/tratamiento farmacológico , Infección Hospitalaria/microbiología , Infección Hospitalaria/mortalidad , Brotes de Enfermedades , Farmacorresistencia Bacteriana Múltiple , Escherichia coli/efectos de los fármacos , Infecciones por Escherichia coli/orina , Femenino , Mortalidad Hospitalaria , Humanos , Infecciones por Klebsiella/orina , Tiempo de Internación , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Riesgo , Reino Unido/epidemiología , beta-Lactamasas/genéticaRESUMEN
Some genotypes of Acinetobacter baumannii, defined by pulsed-field gel electrophoresis (PFGE), have been found in many hospitals. Our aim was to find variable number tandem repeat (VNTR) loci capable of providing discrimination among isolates with highly similar or identical PFGE profiles, to gain insights into the epidemiology. Thirteen loci identified in A. baumannii ATCC 17978 were tested using a panel of isolates that included multiple representatives of genotypes belonging to the three European clonal lineages. Two loci, with repeat units of 9 and 6 bp respectively were selected. Repeat numbers varied between 3 and 29, and 9 and 26 respectively at the two loci. The repeat numbers of representatives of each genotype often differed between hospitals, providing a means of tracking patient transfers and possible transmissions between patients. The results suggest that this analysis accurately reflects the known epidemiological information, and provides a valuable tool for cross-infection studies.
Asunto(s)
Acinetobacter baumannii/clasificación , Acinetobacter baumannii/genética , Técnicas de Tipificación Bacteriana , Dermatoglifia del ADN/métodos , ADN Bacteriano/genética , Repeticiones de Minisatélite , Electroforesis en Gel de Campo Pulsado , Genotipo , Humanos , Epidemiología Molecular/métodos , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Pseudomonas aeruginosa healthcare outbreaks can be time consuming and difficult to investigate. Guidance does not specify which typing technique is most practical for decision-making. AIM: To explore the usefulness of whole-genome sequencing (WGS) in the investigation of a P. aeruginosa outbreak, describing how it compares with pulsed-field gel electrophoresis (PFGE) and variable number tandem repeat (VNTR) analysis. METHODS: Six patient isolates and six environmental samples from an intensive care unit (ICU) positive for P. aeruginosa over two years underwent VNTR, PFGE and WGS. FINDINGS: VNTR and PFGE were required to fully determine the potential source of infection and rule out others. WGS results unambiguously distinguished linked isolates, giving greater assurance of the transmission route between wash-hand basin water and two patients, supporting the control measures employed. CONCLUSION: WGS provided detailed information without the need for further typing. When allied to epidemiological information, WGS can be used to understand outbreak situations rapidly and with certainty. Implementation of WGS in real-time would be a major advance in day-to-day practice. It could become a standard of care as it becomes more widespread due to its reproducibility and lower costs.
Asunto(s)
Infección Hospitalaria/epidemiología , Brotes de Enfermedades , Tipificación Molecular/métodos , Infecciones por Pseudomonas/epidemiología , Pseudomonas aeruginosa/aislamiento & purificación , Secuenciación Completa del Genoma/métodos , Transmisión de Enfermedad Infecciosa , Electroforesis en Gel de Campo Pulsado , Humanos , Unidades de Cuidados Intensivos , Repeticiones de Minisatélite , Epidemiología Molecular , Pseudomonas aeruginosa/clasificación , Pseudomonas aeruginosa/genéticaRESUMEN
Representatives (n = 31) of outbreak strains of Acinetobacter baumannii from five countries fell into three clear groups, designated Groups 1-3, based on their ompA (outer-membrane protein A), csuE (part of a pilus assembly system required for biofilm formation) and bla(OXA-51-like) (the intrinsic carbapenemase gene in A. baumannii) gene sequences. With the exception of the closely related alleles within the Group 1 clonal complex, alleles at each locus were highly distinct from each other, with a minimum of 14 nucleotide differences between any two alleles. Isolates within a group shared the same combination of alleles at the three loci, providing compelling evidence that the outbreak strains investigated belonged to three clonal lineages. These corresponded to the previously identified European clones I-III. Sequence differences among the alleles were used to design multiplex PCRs to rapidly assign isolates belonging to particular genotypes to sequence groups. In the UK, genotypes belonging to the Group 1 clonal complex have been particularly successful, accounting for the vast majority of isolates referred from hospitals experiencing problems with Acinetobacter.
Asunto(s)
Infecciones por Acinetobacter/genética , Acinetobacter baumannii , Infección Hospitalaria/genética , Brotes de Enfermedades/clasificación , Infecciones por Acinetobacter/clasificación , Infecciones por Acinetobacter/epidemiología , Acinetobacter baumannii/clasificación , Acinetobacter baumannii/genética , Acinetobacter baumannii/patogenicidad , Infección Hospitalaria/microbiología , Electroforesis en Gel de Campo Pulsado , Europa (Continente)/epidemiología , Humanos , Israel/epidemiología , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa , Estudios RetrospectivosAsunto(s)
Enterobacter cloacae/enzimología , Enterobacter cloacae/aislamiento & purificación , Infecciones por Enterobacteriaceae/microbiología , Resistencia betalactámica , beta-Lactamasas/biosíntesis , Técnicas de Tipificación Bacteriana , ADN Bacteriano/genética , Electroforesis en Gel de Campo Pulsado , Enterobacter cloacae/clasificación , Enterobacter cloacae/efectos de los fármacos , Humanos , Tipificación Molecular , Reino Unido , beta-Lactamasas/genéticaRESUMEN
A multiresistant clone of Acinetobacter baumannii was identified in 24 hospitals in the UK, predominantly in the London area, over a period of three years. Isolates were characterized by distinctive ApaI macrorestriction profiles, as resolved by pulsed-field gel electrophoresis (PFGE), which all clustered within 80% similarity using a 1% band position tolerance setting. The first isolates identified were received by the reference laboratories in April 2000, and by June 2003, a total of 375 isolates with similar PFGE profiles from 310 patients from 24 hospitals had been received. The isolates originated mainly from sputum and wound specimens, with the majority from patients in intensive care units. Amplified fragment length polymorphism analysis of a subset of isolates showed that they clustered closely, supporting the PFGE results. All the isolates tested were highly resistant to ampicillin, piperacillin, piperacillin/tazobactam, ceftazidime, cefotaxime, gentamicin and ciprofloxacin, and most isolates were carbapenem resistant. Amikacin sensitivity varied from susceptible [minimum inhibitory concentration (MIC)
Asunto(s)
Infecciones por Acinetobacter/epidemiología , Acinetobacter baumannii/efectos de los fármacos , Infección Hospitalaria/epidemiología , Resistencia a Múltiples Medicamentos , Infecciones por Acinetobacter/tratamiento farmacológico , Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii/genética , Antiinfecciosos/farmacología , Antiinfecciosos/uso terapéutico , Infección Hospitalaria/tratamiento farmacológico , Infección Hospitalaria/prevención & control , Dermatoglifia del ADN , Cartilla de ADN , ADN Bacteriano/análisis , Electroforesis en Gel de Campo Pulsado , Humanos , Control de Infecciones , Londres/epidemiología , Pruebas de Sensibilidad Microbiana , PrevalenciaRESUMEN
BACKGROUND: In December 2011 and early 2012 four neonates died from Pseudomonas aeruginosa bacteraemia in hospitals in Northern Ireland. AIM: To assess whether P. aeruginosa was associated with the neonatal unit taps and whether waterborne isolates were consistent with patient isolates. METHODS: Thirty taps and eight flow straighteners from the relevant hospitals were categorized and dismantled into 494 components and assessed for aerobic colony and P. aeruginosa counts using non-selective and selective agars. P. aeruginosa isolates were typed by variable number tandem repeat (VNTR) analysis. Selected tap components were subjected to epifluorescence and scanning electron microscopy to visualize biofilm. FINDINGS: The highest P. aeruginosa counts were from the flow straighteners, metal support collars and the tap bodies surrounding these two components. Complex flow straighteners had a significantly higher P. aeruginosa count than other types of flow straighteners (P < 0.05). Highest aerobic colony counts were associated with integrated mixers and solenoids (P < 0.05), but there was not a strong correlation (r = 0.33) between the aerobic colony counts and P. aeruginosa counts. Representative P. aeruginosa tap isolates from two hospital neonatal units had VNTR profiles consistent with strains from the tap water and infected neonates. CONCLUSION: P. aeruginosa was predominantly found in biofilms in flow straighteners and associated components in the tap outlets and was a possible source of the infections observed. Healthcare providers should be aware that water outlets can be a source of P. aeruginosa contamination and should take steps to reduce such contamination, monitor it and have strategies to minimize risk to susceptible patients.
Asunto(s)
Biopelículas/crecimiento & desarrollo , Infección Hospitalaria/epidemiología , Microbiología Ambiental , Instituciones de Salud , Infecciones por Pseudomonas/epidemiología , Pseudomonas aeruginosa/fisiología , Carga Bacteriana , Infección Hospitalaria/microbiología , Infección Hospitalaria/mortalidad , Agua Potable/microbiología , Fluorescencia , Genotipo , Humanos , Microscopía Electrónica de Rastreo , Repeticiones de Minisatélite , Tipificación Molecular , Irlanda del Norte/epidemiología , Infecciones por Pseudomonas/microbiología , Infecciones por Pseudomonas/mortalidad , Pseudomonas aeruginosa/clasificación , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/aislamiento & purificación , Coloración y EtiquetadoRESUMEN
BACKGROUND: Stenotrophomonas maltophilia causes opportunistic infections and remains a problem pathogen on intensive care unit (ICU) due to its multidrug resistance. AIM: An outbreak of S. maltophilia on ICU is described in order to highlight the risk from contaminated devices for supply of drinking water. METHODS: The outbreak was investigated by a combination of epidemiology, environmental sampling and molecular typing. FINDINGS: From 2009 to 2011 isolates of S. maltophilia from 23 patients were found to belong to only two genotypes by contrast with isolates from 52 other patients during this period, which represented distinct strains. The monthly incidence for all S. maltophilia strains ranged from 0 to 11% and for the two outbreak strains from 0 to 9%. Admission and weekly pharyngeal screening on ICU showed that the outbreak strains were acquired on ICU (range: 3-90 days). The majority of isolates (74%) were from the respiratory tract. Only two of 12 (17%) colonized intubated patients developed pneumonia. Environmental sampling found the two outbreak strains in two sinks and in the drinking water of the cooling unit in the ICU kitchen. S. maltophilia had formed a biofilm in the flexible tube from the carbon filter to the chiller and from the latter to the tap at the kitchen sink. This cooled water was used for providing drinking water and mouth care to ICU patients. The outbreak strains disappeared after removal of the water-cooler and the monthly incidence fell to <2% of ICU admissions. CONCLUSION: This outbreak report highlights the risk from biofilms in devices that supply drinking water for ICU patients.
Asunto(s)
Brotes de Enfermedades , Microbiología Ambiental , Infecciones por Bacterias Gramnegativas/epidemiología , Unidades de Cuidados Intensivos , Stenotrophomonas maltophilia/aislamiento & purificación , Anciano , Biopelículas , Agua Potable , Femenino , Infecciones por Bacterias Gramnegativas/microbiología , Humanos , Masculino , Persona de Mediana Edad , Stenotrophomonas maltophilia/fisiología , Abastecimiento de AguaRESUMEN
BACKGROUND: Carbapenem-resistant Enterobacteriaceae are an emerging global infection threat. However, there are few data describing their clinical importance in children. AIM: This retrospective study reviewed the prevalence and resistance mechanisms of carbapenem-resistant Enterobacteriaceae grown from clinical and surveillance samples in a large tertiary referral children's hospital in the UK. METHODS: Carbapenem-resistant Enterobacteriaceae were sought in specimens submitted for diagnostic and surveillance purposes at Alder Hey Children's NHS Foundation Trust, Liverpool, between September 2011 and August 2012. Mechanisms of resistance were identified using phenotypic and/or molecular methods. Variable number tandem repeat profiling was used to type carbapenemase-producing strains. FINDINGS: During the 12-month study period, carbapenem-resistant Enterobacteriaceae were recovered from 24 patients. Five isolates were from clinical diagnostic specimens whereas 19 of 421 patients had positive rectal surveillance swabs (4.5%). Of the 24 isolates, seven (all Klebsiella spp.) harboured carbapenemases: three had blaKPC and four blaNDM, whereas 17 had resistance due to combinations of AmpC or extended-spectrum ß-lactamase activity plus impermeability. CONCLUSION: Carbapenem-resistant Enterobacteriaceae and, in particular, those with carbapenemases, are an emerging infection problem in a major paediatric hospital in the UK. Active surveillance is required to monitor and control their spread.
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Antibacterianos/farmacología , Carbapenémicos/farmacología , Enfermedades Transmisibles Emergentes/epidemiología , Enfermedades Transmisibles Emergentes/microbiología , Infecciones por Enterobacteriaceae/epidemiología , Enterobacteriaceae/efectos de los fármacos , Resistencia betalactámica , Adolescente , Niño , Preescolar , Enterobacteriaceae/aislamiento & purificación , Infecciones por Enterobacteriaceae/microbiología , Femenino , Hospitales Pediátricos , Humanos , Lactante , Recién Nacido , Masculino , Pruebas de Sensibilidad Microbiana , Repeticiones de Minisatélite , Tipificación Molecular , Reacción en Cadena de la Polimerasa , Prevalencia , Estudios Retrospectivos , Centros de Atención Terciaria , Reino Unido/epidemiologíaRESUMEN
The purpose of this study was to identify molecular and epidemiological characteristics of hospital-acquired carbapenem-resistant Acinetobacter baumannii (CRAB) from two different intensive care unit (ICU) settings in Karachi, Pakistan. A cross-sectional study was performed in the adult ICUs of a private sector tertiary care hospital (PS-ICU) and of a government sector hospital (GS-ICU) between November 2007 and August 2008. Deduplicated CRAB isolates from clinical specimens were examined for carbapenemase and class 1 integrase genes. Isolates were typed using sequence-based multiplex polymerase chain reaction, pulsed-field gel electrophoresis (PFGE) and variable number tandem repeat (VNTR). A total of 50 patients (33 from PS-ICU and 17 from GS-ICU) were recruited. There were statistically significant differences between patients in the two ICUs in terms of mean age, comorbidities, the presence of central venous pressure lines, urinary catheters, and average length of stay. bla(OxA-23-like) acquired-oxacillinase genes were found in 47/50 isolates. Class 1 integrase genes were found in 50% (25/50) of the organisms. The majority of isolates belonged to strains of European clones I and II. PFGE typing grouped the isolates into eight distinct clusters, three of which were found in both hospitals. Most of the isolates within each PFGE cluster shared identical or highly similar VNTR profiles, suggesting close epidemiological association. Irrespective of differences in risk factors and infection control policies and practices, the extent of clonality among CRAB isolates was very similar in both ICU settings.
Asunto(s)
Infecciones por Acinetobacter/epidemiología , Acinetobacter baumannii/genética , Antibacterianos/farmacología , Carbapenémicos/farmacología , Farmacorresistencia Bacteriana , Unidades de Cuidados Intensivos/estadística & datos numéricos , Epidemiología Molecular , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/clasificación , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/aislamiento & purificación , Adulto , Anciano , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Estudios Transversales , Femenino , Humanos , Integrasas/genética , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Pakistán/epidemiología , Sector Privado , Sector Público , Adulto Joven , beta-Lactamasas/genéticaRESUMEN
Repeat numbers at nine variable-number tandem-repeat (VNTR) loci were determined for 177 isolates of Pseudomonas aeruginosa representing 77 strains distinguished by pulsed-field gel electrophoresis (PFGE). Eight loci provided for discrimination similar to that provided by PFGE, with variation at the ninth locus (ms61) sometimes allowing discrimination within a PFGE-defined type. The Liverpool and Midlands 1 strains, which are common among patients with cystic fibrosis in the UK, could be unambiguously identified by their characteristic VNTR profiles. In rare cases, the repeat number at the ninth locus alone provided discrimination among isolates that were distinct according to PFGE. In each case, the two isolates shared the same bla(OXA-50-like) allele and belonged to the same oprD sequence type group, supporting the VNTR results in suggesting that they are similar.
Asunto(s)
Técnicas de Tipificación Bacteriana , Dermatoglifia del ADN , Repeticiones de Minisatélite , Pseudomonas aeruginosa/clasificación , Pseudomonas aeruginosa/genética , Análisis por Conglomerados , Fibrosis Quística/complicaciones , ADN Bacteriano/química , ADN Bacteriano/genética , Electroforesis en Gel de Campo Pulsado , Genotipo , Humanos , Datos de Secuencia Molecular , Porinas/genética , Infecciones por Pseudomonas/microbiología , Pseudomonas aeruginosa/aislamiento & purificación , Sensibilidad y Especificidad , Análisis de Secuencia de ADN , Reino Unido , beta-Lactamasas/genéticaRESUMEN
Bla(OXA-51-like), the intrinsic carbapenemase gene in Acinetobacter baumannii previously found only in this species, was detected in a clinical isolate of Acinetobacter genomic species 13tU. this study aimed to characterize this gene in the isolate. Genomic species identification was confirmed by amplified ribosomal DNA restriction analysis and sequence analysis of 16S-23S ribosomal DNA intergenic spacer, rpoB and recA. The bla(OXA-51-like) gene, with an upstream ISAba1 insertion, was plasmid-encoded and the surrounding sequences suggested that its origin was from A. baumannii. Transformation of Acinetobacter genomic species 13TU AtCC 17903 with recombinant plasmid bearing ISAba1-bla(OXA-51-like) from the isolate increased the minimum inhibitory concentrations (MICs) of meropenem and imipenem 256-fold. This is the first report of bla(OXA-51-like) in an organism other than A. baumannii. This plasmid-borne bla(OXA-51-like) gene with an upstream ISAba1 insertion confers a high level of carbapenem resistance to Acinetobacter genomic species 13TU.
Asunto(s)
Acinetobacter baumannii/genética , Acinetobacter/genética , Proteínas Bacterianas/genética , beta-Lactamasas/genética , Acinetobacter/aislamiento & purificación , Acinetobacter baumannii/aislamiento & purificación , Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Southern Blotting , ADN Bacteriano/genética , ADN Ribosómico/genética , Farmacorresistencia Bacteriana , Genotipo , Humanos , Pruebas de Sensibilidad Microbiana , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16S/genética , ARN Ribosómico 23S/genética , beta-Lactamasas/metabolismoRESUMEN
The gln-gamma gene, which specifies the gamma subunit of glutamine synthetase in Phaseolus vulgaris L., has been isolated and the regulatory properties of its promoter region analyzed in transgenic Lotus corniculatus plants. A 2-kilobase fragment from the 5'-flanking region of gln-gamma conferred a strongly nodule-enhanced pattern of expression on the beta-glucuronidase reporter gene. Parallel studies on the promoter of another glutamine synthetase gene (gln-beta) showed that a 1.7-kilobase fragment directed 20-fold to 140-fold higher levels of beta-glucuronidase expression in roots than in shoots. Histochemical localization of beta-glucuronidase activity in nodules of the transgenic plants indicated that the chimeric gln-gamma gene was expressed specifically in the rhizobially infected cells; expression of the gln-beta construct was detected in both cortical and infected regions of young nodules, and became restricted to the vascular tissue as the nodule matured. We conclude that gln-beta and gln-gamma genes are differentially expressed both temporally and spatially in plant development and that the cis-acting regulatory elements responsible for conferring these contrasting expression patterns are located within a 2-kilobase region upstream of their coding sequences.