Genomic resistant determinants of multidrug-resistant Campylobacter spp. isolates in Peru.

OBJECTIVES: Antimicrobial resistant (AMR) Campylobacter is a global health threat; however, there is limited information on genomic determinants of resistance in low- and middle-income countries. We evaluated genomic determinants of AMR using a collection of whole genome sequenced Campylobacter jejuni and C. coli isolates from Iquitos, Peru. METHODS: Campylobacter isolates from two paediatric cohort studies enriched with isolates that demonstrated resistance to ciprofloxacin and azithromycin were sequenced and mined for AMR determinants. RESULTS: The gyrA mutation leading to the Thr86Ile amino acid change was the only gyrA mutation associated with fluoroquinolone resistance identified. The A2075G mutation in 23S rRNA was present, but three other 23S rRNA mutations previously associated with macrolide resistance were not identified. A resistant-enhancing variant of the cmeABC efflux pump genotype (RE-cmeABC) was identified in 36.1% (35/97) of C. jejuni genomes and 17.9% (12/67) of C. coli genomes. Mutations identified in the CmeR-binding site, an inverted repeat sequence in the cmeABC promoter region that increases expression of the operon, were identified in 24/97 C. jejuni and 14/67 C. coli genomes. The presence of these variants, in addition to RE-cmeABC, was noted in 18 of the 24 C. jejuni and 9 of the 14 C. coli genomes. CONCLUSIONS: Both RE-cmeABC and mutations in the CmeR-binding site were strongly associated with the MDR phenotype in C. jejuni and C. coli. This is the first report of RE-cmeABC in Peru and suggests it is a major driver of resistance to the principal therapies used to treat human campylobacteriosis in this setting.

Reflections on the impact and response to the Peruvian 2017 Coastal El Niño event: Looking to the past to prepare for the future.

Climate-related phenomena in Peru have been slowly but continuously changing in recent years beyond historical variability. These include sea surface temperature increases, irregular precipitation patterns and reduction of glacier-covered areas. In addition, climate scenarios show amplification in rainfall variability related to the warmer conditions associated with El Niño events. Extreme weather can affect human health, increase shocks and stresses to the health systems, and cause large economic losses. In this article, we study the characteristics of El Niño events in Peru, its health and economic impacts and we discuss government preparedness for this kind of event, identify gaps in response, and provide evidence to inform adequate planning for future events and mitigating impacts on highly vulnerable regions and populations. This is the first case study to review the impact of a Coastal El Niño event on Peru's economy, public health, and governance. The 2017 event was the third strongest El Niño event according to literature, in terms of precipitation and river flooding and caused important economic losses and health impacts. At a national level, these findings expose a need for careful consideration of the potential limitations of policies linked to disaster prevention and preparedness when dealing with El Niño events. El Niño-related policies should be based on local-level risk analysis and efficient preparedness measures in the face of emergencies.

First Report of OXA-181-Producing Enterobacterales Isolates in Latin America.

We characterized five carbapenemase-producing Enterobacterales (CPE) isolates from two health care institutions in Lima, Peru. The isolates were identified as Klebsiella pneumoniae (n = 3), Citrobacter portucalensis (n = 1), and Escherichia coli (n = 1). All were identified as blaOXA-48-like gene carriers using conventional PCR. Whole-genome sequencing found the presence of the blaOXA-181 gene as the only carbapenemase gene in all isolates. Genes associated with resistance to aminoglycosides, quinolones, amphenicols, fosfomycins, macrolides, tetracyclines, sulfonamides, and trimethoprim were also found. The plasmid incompatibility group IncX3 was identified in all genomes in a truncated Tn6361 transposon flanked by ΔIS26 insertion sequences. The qnrS1 gene was also found downstream of blaOXA-181, conferring fluoroquinolone resistance to all isolates. CPE isolates harboring blaOXA-like genes are an increasing public health problem in health care settings worldwide. The IncX3 plasmid is involved in the worldwide dissemination of blaOXA-181, and its presence in these CPE isolates suggests the wide dissemination of blaOXA-181 in Peru. IMPORTANCE Reports of carbapenemase-producing Enterobacterales (CPE) isolates are increasing worldwide. Accurate detection of the ß-lactamase OXA-181 (a variant of OXA-48) is important to initiate therapy and preventive measures in the clinic. OXA-181 has been described in CPE isolates in many countries, often associated with nosocomial outbreaks. However, the circulation of this carbapenemase has yet to be reported in Peru. Here, we report the detection of five multidrug-resistant CPE clinical isolates harboring blaOXA-181 in the IncX3-type plasmid, a potential driver of dissemination in Peru.

Factors associated with diphtheria vaccination completion among children under five years old in Peru 2010-2019: A cross-sectional population-based study.

The World Health Organization (WHO) recommends a minimum of 90% coverage of diphtheria three-dose complete vaccination scheme (DPT) as part of routine immunization programs in children. However, diphtheria coverage in Peru has not reached the minimum recommended during the last decades. Our study aimed to determine the complete three-dose DPT coverage and factors associated with compliance towards complete vaccination in Peru between 2010-2019. We conducted a secondary cross-sectional study using the "Encuesta Demográfica y de Salud Familiar (ENDES)"- Demographic and Family Health Survey, which is a survey that targets mothers between 15 and 49 years of age. DPT vaccination coverage was 72.4% and several factors were associated with the DPT scheme completion. Women in the age groups 18 to 24 (ORa = 2.31, 95%CI: 2.11-2.52), 25 to 34 (ORa = 3.37, 95% CI: 3.08-3.69), and 35 to 49 (ORa = 4.74, 95% CI: 4.29-5.22) were more likely to complete their children's DPT vaccination scheme compared to those between 15 to 17 years of age. Both Spanish (ORa = 1.39, 95% CI: 1.31-1.48) and Quechua (ORa = 1.34, 95% CI: 1.25-1.43) as first spoken language were associated with DPT completion compared to native language speaking mothers. Women who worked (ORa = 1.72, 95% CI: 1.57-1.88), studied (ORa = 1.47, 95% CI: 1.33-1.62), or were housewives (ORa = 1.41, 95% CI: 1.29-1.54) during the previous week were more likely to complete their children's DPT scheme compared to participants that did not work during the previous week. Women with the financial capability to access health care were less likely to complete the DPT scheme (ORa = 0.95, 95% CI: 0.92-0.97). Considering the accessibility to health care centers, women who knew the nearest location (ORa = 1.07, 95% CI: 1.03-1.11), had geographic accessibility (ORa = 1.09, 95% CI: 1.06-1.13) or a current transport (ORa = 1.06, 95% CI: 1.02-1.09) were more likely to complete their children 's DPT scheme. Our results highlight low diphtheria vaccine coverage levels in Peru, with values lower than what is recommended by the WHO. Results may serve as a baseline for future studies to improve vaccination programs, reduce barriers and increase DPT coverage in Peru.

Antibiotic Use and Resistance Knowledge Assessment of Personnel on Chicken Farms with High Levels of Antimicrobial Resistance: A Cross-Sectional Survey in Ica, Peru.

Poultry farming represents Peru's primary food animal production industry, where antimicrobial growth promoters are still commonly used, exerting selective pressure on intestinal microbial populations. Consumption and direct animal-to-human transmission have been reported, and farmworkers are at high risk of colonization with resistant bacteria. We conducted a cross-sectional survey among 54 farmworkers to understand their current antimicrobial resistance (AMR) awareness in Ica, Peru. To gain insight into the potential work-related risk of exposure to bacteria, we also measured the AMR rates in Escherichia coli isolated among 50 broiler chickens. Farmworkers were unaware of antimicrobial resistance (31.5%) or antibiotic resistance (16.7%) terms. Almost two-thirds (61%) consumed antibiotics during the previous month, and only 42.6% received a prescription from a healthcare professional. A total of 107 E. coli chicken isolates were obtained, showing a high frequency of multidrug-resistant (89.7%) and extended-spectrum beta-lactamase (ESBL) production (71.9%). Among ESBL-producer isolates, 84.4% carried the blaCTX-M gene. Results identified gaps in knowledge that reflect the need for interventions to increase antimicrobial awareness among poultry farmworkers. The high AMR rates among E. coli isolates highlight the need to reduce antimicrobial use in poultry farms. Our findings reveal a critical need for effective policy development and antimicrobial stewardship interventions in poultry production in Ica, Peru.

First Detection and Genome Sequencing of SARS-CoV-2 Lambda (C.37) Variant in Symptomatic Domestic Cats in Lima, Peru.

The role of domestic cats in the dynamics of SARS-CoV-2 remains poorly characterized, especially in epidemiologic contexts of countries with high viral transmission. Here, we report the first evidence of SARS-CoV-2 Lambda variant of interest in symptomatic domestic cats whose owners were diagnosed with COVID-19 in Lima, Peru, providing evidence that transmission of this new variant in domestic cats is occurring. More epidemiological studies are required to further characterize the role of domestic animals in the transmission dynamics of SARS-CoV-2.

Frequency of colistin resistance in Pseudomonas aeruginosa: first report from Peru. / Frecuencia de resistencia a la colistina en Pseudomonas aeruginosa: primer reporte en el Perú.

This study aimed to determine the frequency of colistin resistance in Pseudomonas aeruginosa isolates obtained from three healthcare facilities in Lima and cryopreserved at the Laboratorio de Resistencia Antimicrobianos e Inmunopatología of the Universidad Peruana Cayetano Heredia (UPCH). The colistin broth disk elution method was used for the phenotypic identification of colistin resistance. We detected the expression of the mcr-1 gene by using the phenotypic diffusion method with combined colistin and ethylenediaminetetraacetic acid (EDTA) disks; and polymerase chain reaction (PCR) was used for molecular identification of the gene. Of the 97 isolates, 7 (7.2%) were resistant to colistin; however, none carried the mcr-1 gene. This is the first report from Peru on clinical isolates of colistin-resistant Pseudomonas aeruginosa, which suggests the need for implementation of appropriate methodologies for the epidemiological surveillance of colistin-resistant pathogens.

El objetivo del estudio fue determinar la frecuencia de resistencia a la colistina en Pseudomonas aeruginosa provenientes de tres establecimientos de salud de Lima, criopreservados en el banco de cepas del Laboratorio de Resistencia a Antimicrobianos e Inmunopatología de la Universidad Peruana Cayetano Heredia (UPCH). El método de elución de discos de colistina en caldo fue empleado para la identificación fenotípica de la resistencia a la colistina; la detección de la expresión del gen mcr-1 se realizó mediante el método fenotípico de difusión de discos combinados de colistina y ácido etilendiaminotetraacético (EDTA) y la reacción en cadena de la polimerasa (PCR) para la identificación molecular del gen. De los 97 aislados estudiados, 7 (7,2%) fueron resistentes a la colistina y ninguno fue portador del gen mcr-1. Este estudio constituye el primer reporte en el Perú de aislados clínicos de Pseudomonas aeruginosa resistentes a la colistina, lo que implica la necesidad de implementar metodologías apropiadas para la vigilancia epidemiológica de patógenos resistentes a la colistina.

Draft Genome Sequence of a blaKPC-2-Carrying Citrobacter braakii Isolate from Pediatric Hospital Wastewater in Peru.

Here, we report a draft genome sequence of a blaKPC-2-carrying Citrobacter braakii isolate from pediatric hospital effluent. Genome CF248 represents a multidrug-resistant C. braakii isolate derived from a clinical environment in Peru.

Microbiological and molecular characterization of antimicrobial resistance in uropathogenic Escherichia coli from peruvian public hospitals. / Caracterización microbiológica y molecular de la resistencia antimicrobiana de Escherichia coli uropatógenas de hospitales públicos peruanos.

We characterized the antimicrobial resistance of 70 Escherichia coli isolates obtained from patients with a urinary tract infection (UTI) from 8 public hospitals in Peru. Resistance profiles were identified using the automated MicroScan® system. A standard polymerase chain reaction was used for the detection of the bla TEM, bla CTX-M, bla SHV and bla PER genes. The 65.7% (46/70) of the isolates presented a multidrug-resistant phenotype and 55.7% (39/70) were extended-spectrum beta-lactamases producers. High levels of resistance were detected for ampicillin (77,1%), ciprofloxacin (74,3%), trimethoprim/sulfamethoxazole (62,9%), cefepime (57,1%), and cefuroxime (57,1%). The bla TEM gene was the most frequent (31,4%), followed by bla CTX-M (18,6%) and bla SHV (2,9%) genes. These results show high resistance levels to antimicrobials of clinical use in E. coli isolates from hospital UTI patients in Peru.

Se caracterizó la resistencia antimicrobiana de 70 aislados de Escherichia coli obtenidos de pacientes con infección del tracto urinario (ITU) provenientes de ocho hospitales públicos en el Perú. Los perfiles de resistencia fueron identificados mediante el uso del sistema automatizado MicroScan®. Se utilizó una reacción en cadena de la polimerasa convencional para la detección de los genes bla TEM, bla CTX-M, bla SHV y bla PER. El 65,7% (46/70) de los aislados presentó un fenotipo multidrogorresistente y el 55,7% (39/70) fue identificado como productores de betalactamasas de espectro extendido. Se detectaron altos niveles de resistencia para ampicilina (77,1%), ciprofloxacina (74,3%), trimetoprim/sulfametoxazol (62,9%), cefepime (57,1%) y cefuroxima (57,1%). El gen bla TEM fue el más frecuente con un 31,4%, seguido por bla CTX-M (18,6%) y bla SHV (2,9%). Los resultados evidencian altos niveles de resistencia a antimicrobianos de importancia clínica en aislados de E. coli de pacientes con ITU en el Perú.

Antimicrobial Resistance Patterns and Dynamics of Extended-Spectrum ß-Lactamase-Producing Uropathogenic Escherichia coli in Cusco, Peru.

Urinary tract infections (UTIs) are a common human infection. Antibiotic resistance in extended-spectrum ß-lactamase (ESBL)-producing uropathogenic E. coli (UPEC) is a major therapeutic challenge due to limited treatment alternatives. The aim was to characterize the antimicrobial resistance (AMR) and dynamics of ESBL-producing UPEC isolates from UTI cases seen at a local hospital in Cusco, Peru. Ninety-nine isolates from respective patients were characterized against 18 different antibiotics. Latent class analysis (LCA) was used to evaluate the dynamics across the study time according to resistance patterns. The median age of patients was 51 years old, and nearly half were women. ESBL-producing UPEC isolates were slightly more frequent in outpatient services than emergency rooms, and there were higher resistance rates in males compared to females. Half of the ESBL producers were resistant to aminoglycosides and nitrofurantoin. Cefoxitin and fosfomycin resistance was 29.3% and 14.1%, respectively. Resistance to carbapenems was not observed. All isolates were multidrug-resistant bacteria, and 16.2% (16/99) were also classified as extensively drug-resistant bacteria. The resistance patterns varied across the study time and differed regarding sex and healthcare service. The study revealed high levels of AMR to commonly used antimicrobials and a dynamic circulation of ESBL-producing UPEC isolates with varying resistance patterns.

Market Chickens as a Source of Antibiotic-Resistant Escherichia coli in a Peri-Urban Community in Lima, Peru.

The widespread and poorly regulated use of antibiotics in animal production in low- and middle-income countries (LMICs) is increasingly associated with the emergence and dissemination of antibiotic resistance genes (ARGs) in retail animal products. Here, we compared Escherichia coli from chickens and humans with varying levels of exposure to chicken meat in a low-income community in the southern outskirts of Lima, Peru. We hypothesize that current practices in local poultry production result in highly resistant commensal bacteria in chickens that can potentially colonize the human gut. E. coli was isolated from cloacal swabs of non-organic (n = 41) and organic chickens (n = 20), as well as from stools of market chicken vendors (n = 23), non-vendors (n = 48), and babies (n = 60). 315 E. coli isolates from humans (n = 150) and chickens (n = 165) were identified, with chickens showing higher rates of multidrug-resistant and extended-spectrum beta-lactamase phenotypes. Non-organic chicken isolates were more resistant to most antibiotics tested than human isolates, while organic chicken isolates were susceptible to most antibiotics. Whole-genome sequencing of 118 isolates identified shared phylogroups between human and animal populations and 604 ARG hits across genomes. Resistance to florfenicol (an antibiotic commonly used as a growth promoter in poultry but not approved for human use) was higher in chicken vendors compared to other human groups. Isolates from non-organic chickens contained genes conferring resistance to clinically relevant antibiotics, including mcr-1 for colistin resistance, blaCTX-M ESBLs, and blaKPC-3 carbapenemase. Our findings suggest that E. coli strains from market chickens are a potential source of ARGs that can be transmitted to human commensals.

Caracterización microbiológica y molecular de la resistencia antimicrobiana de Escherichia coli uropatógenas de hospitales públicos peruanos / Microbiological and molecular characterization of antimicrobial resistance in uropathogenic Escherichia coli from peruvian public hospitals

RESUMEN Se caracterizó la resistencia antimicrobiana de 70 aislados de Escherichia coli obtenidos de pacientes con infección del tracto urinario (ITU) provenientes de ocho hospitales públicos en el Perú. Los perfiles de resistencia fueron identificados mediante el uso del sistema automatizado MicroScan®. Se utilizó una reacción en cadena de la polimerasa convencional para la detección de los genes bla TEM, bla CTX-M, bla SHV y bla PER. El 65,7% (46/70) de los aislados presentó un fenotipo multidrogorresistente y el 55,7% (39/70) fue identificado como productores de betalactamasas de espectro extendido. Se detectaron altos niveles de resistencia para ampicilina (77,1%), ciprofloxacina (74,3%), trimetoprim/sulfametoxazol (62,9%), cefepime (57,1%) y cefuroxima (57,1%). El gen bla TEM fue el más frecuente con un 31,4%, seguido por bla CTX-M (18,6%) y bla SHV (2,9%). Los resultados evidencian altos niveles de resistencia a antimicrobianos de importancia clínica en aislados de E. coli de pacientes con ITU en el Perú.

ABSTRACT We characterized the antimicrobial resistance of 70 Escherichia coli isolates obtained from patients with a urinary tract infection (UTI) from 8 public hospitals in Peru. Resistance profiles were identified using the automated MicroScan® system. A standard polymerase chain reaction was used for the detection of the bla TEM, bla CTX-M, bla SHV and bla PER genes. The 65.7% (46/70) of the isolates presented a multidrug-resistant phenotype and 55.7% (39/70) were extended-spectrum beta-lactamases producers. High levels of resistance were detected for ampicillin (77,1%), ciprofloxacin (74,3%), trimethoprim/sulfamethoxazole (62,9%), cefepime (57,1%), and cefuroxime (57,1%). The bla TEM gene was the most frequent (31,4%), followed by bla CTX-M (18,6%) and bla SHV (2,9%) genes. These results show high resistance levels to antimicrobials of clinical use in E. coli isolates from hospital UTI patients in Peru.

Caracterización microbiológica y molecular de la resistencia antimicrobiana de Escherichia coli uropatógenas de hospitales públicos peruanos / Microbiological and molecular characterization of antimicrobial resistance in uropathogenic Escherichia coli from peruvian public hospitals

RESUMEN Se caracterizó la resistencia antimicrobiana de 70 aislados de Escherichia coli obtenidos de pacientes con infección del tracto urinario (ITU) provenientes de ocho hospitales públicos en el Perú. Los perfiles de resistencia fueron identificados mediante el uso del sistema automatizado MicroScan®. Se utilizó una reacción en cadena de la polimerasa convencional para la detección de los genes bla TEM, bla CTX-M, bla SHV y bla PER. El 65,7% (46/70) de los aislados presentó un fenotipo multidrogorresistente y el 55,7% (39/70) fue identificado como productores de betalactamasas de espectro extendido. Se detectaron altos niveles de resistencia para ampicilina (77,1%), ciprofloxacina (74,3%), trimetoprim/sulfametoxazol (62,9%), cefepime (57,1%) y cefuroxima (57,1%). El gen bla TEM fue el más frecuente con un 31,4%, seguido por bla CTX-M (18,6%) y bla SHV (2,9%). Los resultados evidencian altos niveles de resistencia a antimicrobianos de importancia clínica en aislados de E. coli de pacientes con ITU en el Perú.

ABSTRACT We characterized the antimicrobial resistance of 70 Escherichia coli isolates obtained from patients with a urinary tract infection (UTI) from 8 public hospitals in Peru. Resistance profiles were identified using the automated MicroScan® system. A standard polymerase chain reaction was used for the detection of the bla TEM, bla CTX-M, bla SHV and bla PER genes. The 65.7% (46/70) of the isolates presented a multidrug-resistant phenotype and 55.7% (39/70) were extended-spectrum beta-lactamases producers. High levels of resistance were detected for ampicillin (77,1%), ciprofloxacin (74,3%), trimethoprim/sulfamethoxazole (62,9%), cefepime (57,1%), and cefuroxime (57,1%). The bla TEM gene was the most frequent (31,4%), followed by bla CTX-M (18,6%) and bla SHV (2,9%) genes. These results show high resistance levels to antimicrobials of clinical use in E. coli isolates from hospital UTI patients in Peru.

Frecuencia de resistencia a la colistina en Pseudomonas aeruginosa: primer reporte en el Perú

El objetivo del estudio fue determinar la frecuencia de resistencia a la colistina en Pseudomonas aeruginosa provenientes de tres establecimientos de salud de Lima, criopreservados en el banco de cepas del Laboratorio de Resistencia a Antimicrobianos e Inmunopatología de la Universidad Peruana Cayetano Heredia (UPCH). El método de elución de discos de colistina en caldo fue empleado para la identificación fenotípica de la resistencia a la colistina; la detección de la expresión del gen mcr-1 se realizó mediante el método fenotípico de difusión de discos combinados de colistina y ácido etilendiaminotetraacético (EDTA) y la reacción en cadena de la polimerasa (PCR) para la identificación molecular del gen. De los 97 aislados estudiados, 7 (7,2%) fueron resistentes a la colistina y ninguno fue portador del gen mcr-1. Este estudio constituye el primer reporte en el Perú de aislados clínicos de Pseudomonas aeruginosa resistentes a la colistina, lo que implica la necesidad de implementar metodologías apropiadas para la vigilancia epidemiológica de patógenos resistentes a la colistina.

This study aimed to determine the frequency of colistin resistance in Pseudomonas aeruginosa isolates obtained from three healthcare facilities in Lima and cryopreserved at the Laboratorio de Resistencia Antimicrobianos e Inmunopatología of the Universidad Peruana Cayetano Heredia (UPCH). The colistin broth disk elution method was used for the phenotypic identification of colistin resistance. We detected the expression of the mcr-1 gene by using the phenotypic diffusion method with combined colistin and ethylenediaminetetraacetic acid (EDTA) disks; and polymerase chain reaction (PCR) was used for molecular identification of the gene. Of the 97 isolates, 7 (7.2%) were resistant to colistin; however, none carried the mcr-1 gene. This is the first report from Peru on clinical isolates of colistin-resistant Pseudomonas aeruginosa, which suggests the need for implementation of appropriate methodologies for the epidemiological surveillance of colistin-resistant pathogens.

Draft Genome Sequence of a New Delhi Metallo-ß-Lactamase (NDM-1)-Producing Providencia stuartii Strain Isolated in Lima, Peru.

Providencia stuartii is an opportunistic pathogen of the Enterobacteriales order. Here, we report the 4,594,658-bp draft genome sequence of a New Delhi metallo-ß-lactamase (NDM-1)-producing Providencia stuartii strain that was isolated from an emergency patient in a private clinic in Lima, Peru.

SAGE transcript profiling of the juvenile cambial region of Eucalyptus grandis.

Despite the importance of Eucalyptus spp. in the pulp and paper industry, functional genomic approaches have only recently been applied to understand wood formation in this genus. We attempted to establish a global view of gene expression in the juvenile cambial region of Eucalyptus grandis Hill ex Maiden. The expression profile was obtained from serial analysis of gene expression (SAGE) library data produced from 3- and 6-year-old trees. Fourteen-base expressed sequence tags (ESTs) were searched against public Eucalyptus ESTs and annotated with GenBank. Altogether 43,304 tags were generated producing 3066 unigenes with three or more copies each, 445 with a putative identity, 215 with unknown function and 2406 without an EST match. The expression profile of the juvenile cambial region revealed the presence of highly frequent transcripts related to general metabolism and energy metabolism, cellular processes, transport, structural components and information pathways. We made a quantitative analysis of a large number of genes involved in the biosynthesis of cellulose, pectin, hemicellulose and lignin. Our findings provide insight into the expression of functionally related genes involved in juvenile wood formation in young fast-growing E. grandis trees.

Comparison of the expression profiles of susceptible and resistant Eucalyptus grandis exposed to Puccinia psidii Winter using SAGE.

Eucalyptus grandis Hill ex Maiden and its hybrids are commonly planted by the Brazilian pulp and paper industry, but they are the most susceptible to the neotropical rust disease caused by Puccinia psidii Winter. In an initial attempt to understand the mechanisms of resistance, we constructed two contrasting Serial Analysis of Gene Expression (SAGE) libraries using susceptible and resistant individuals from a segregating half-sibling E. grandis population. Using the Z-test we identified tags differentially expressed between the libraries, preferentially 239 in the susceptible and 232 in the resistant type individuals. Using public (Expressed Sequence Tags) EST databases, 40 of the susceptible and 70 of the resistant tags matched ESTs and were annotated. By comparing the type of genes and their expression levels, distinct differences between the libraries were observed. Susceptible plants showed gene expression linked to leaf senescence, generalised stress responses and detoxification, and are apparently incapable of inducing a competent host defence response. On the other hand, resistant plants showed genes upregulated for cellular polarisation, cytoskeleton restructuring, vesicle transport, and cellulose and lignin biosynthesis. In the resistant individuals, evidence for systemic resistance, anti-oxidative responses and a hypersensitive response was also observed, although no R gene was identified.