Neoadjuvant chemotherapy has become standard practice in patients with high-risk early breast cancer as it improves rates of breast conservation surgery and enables prediction of recurrence and survival by using response to treatment as a surrogate. Previous studies have focused on generating molecular datasets to develop prediction models of response, though little is known on how tumours and their microenvironments are modulated by neoadjuvant chemotherapy. The thesis aims at molecularly characterising tumour changes during neoadjuvant chemotherapy in a cohort of 168 patients. Serial tumour samples at diagnosis, and, when available, midway through chemotherapy and on completion of treatment were profiled by shallow whole genome sequencing, deep exome sequencing and transcriptome sequencing, resulting in the generation of an unprecedented genomics dataset with tumours in situ while patients received chemotherapy. Molecular predictors of response to chemotherapy were inferred from the diagnostic biopsy. Several novel observations were made, including previously undescribed associations between copy number alterations, mutational genotypes, neoantigen load, HLA genotypes and intra-tumoural heterogeneity with chemosensitivity. Possible mechanisms of chemoresistance included LOH at the MHC Class I locus, decreased expression of MHC Class I and II genes and drug influx molecules, as well as increased expression of drug efflux pumps. A complex relationship between proliferation, tumour microenvironment composition (TME) and response to treatment was explored by deconvoluting bulk RNAseq data and performing digital pathology orthogonal validation. Clonal and microenvironment dynamic changes induced by/associated with chemotherapy were then modelled. Two types of genomic responses were identified, one in which the clonal composition was stable throughout treatment and another where clonal emergence and/or extinction was evident. Validation by multi-region deep sequencing confirmed the dynamics of the clonal landscape. Clonal emergence was shown to be associated with higher proliferation and decreased immune infiltrate, with an increase in genomic instability and homologous recombination deficiency during treatment. The immune TME composition and activity mirrored response to treatment, with cytolytic activity and innate and adaptive immune infiltrates linearly correlating with the degree of residual disease remaining after chemotherapy. Finally, the circulating tumour DNA (ctDNA) genomic landscape was explored by using shallow whole genome sequencing and targeted sequencing of plasma DNA. Tumour mutations detected on exome sequencing were also detected in ctDNA in plasma, supporting the use of liquid biopsies as a biomarker for monitoring response to therapy and detection of minimal residual disease.

Streptococcus pneumoniae (the pneumococcus) is a bacterial pathogen responsible for >1.6 million annual deaths globally. Pneumococcal penicillin-resistance is conferred by acquisition of ‘altered’ penicillin-binding protein (pbp) genes. The first penicillin-nonsusceptible pneumococci were identified in the late 1960s. Global pneumococcal penicillin-nonsusceptibility rates rapidly increased in the 1980s/90s. Since 2000, protein-conjugate vaccines, targeting 7, 10 or 13 of the ≥94 different pneumococcal capsule types (serotypes), have been introduced in many countries. Following vaccine implementation there has been a decline in vaccine-type pneumococcal disease and an increase in non-vaccine-type disease. These epidemiological changes result from “serotype replacement” and/or “serotype switching”. The former describes the expansion of non-vaccine-type clones in the absence of vaccine-type pneumococci. The latter describes serotype change following recombination at the capsule polysaccharide synthesis (cps) locus. To fully understand how pneumococci respond to vaccine- and antibiotic-induced selective pressures, we must better understand the evolutionary history of this pathogen. This thesis describes the study of a global collection of 426 pneumococci, dated 1937 - 2007. Serotype, genotype and penicillin-susceptibility data were collected. Nucleotide sequences of three pbp genes (for 389 isolates) and whole-genome sequences (for 96 isolates) were also generated. The data demonstrated the long-term persistence of certain clones within pneumococcal populations, and that pbp and large-fragment (>30 kb) cps ± pbp recombination was occurring prior to both widespread antibiotic use and vaccine implementation. The data highlighted the promiscuous nature of the globally-distributed PMEN1 clone and its contribution to the spread of pneumococcal penicillin-resistance. PMEN1 also donated multiple, large regions (1.7 - 32.3 kb) of its genome to at least two un-related clones. Finally, six “Tn916-like” genetic elements, conferring resistance to non-penicillin antibiotics, were newly identified. These included two of the oldest ever described. These results provided a unique insight into the history of pneumococcal evolution and the importance of genetic recombination.

Made available in DSpace on 2016-08-10T10:53:36Z (GMT). No. of bitstreams: 1 MARCIANO DE SOUSA NOBREGA.pdf: 616658 bytes, checksum: 0673ba9db2600506e22ee2169eef0af7 (MD5) Previous issue date: 2012-05-14 / The increase in bacterial resistance occurs in all regions of the world, especially in critically ill patients hospitalized in intensive care units (ICUs) and that make use of several antimicrobials. Bacterial resistance complicates therapy prolongs the ICU stay and increased morbidity and mortality. Among the microorganisms that cause infections in ICUs, we highlight P. aeruginosa and A. baumannii, gram-negative high incidence of nosocomial infections and have shown a tendency to increased antimicrobial resistance. OBJECTIVE: To evaluate microbial and bacterial resistance in adult intensive care agents P. aeruginosa and A. baumannii. MATERIALS AND METHODS: Retrospective study from January 2007 to December 2010 on the sensitivity and P. aeruginosa and A. baumannii in adult ICU patients (medical and surgical) of HC / UFG, with a diagnosis of hospital infection. We analyzed the evolution of resistance, antimicrobial consumption, mortality, topography of infections and length of stay in the units. 121 cases have been cataloged. RESULTS: The mean age of patients was 51.2 ± 17.9 years, male 45.45% and 55.55% female, mean ICU stay was 26.99 days, compared with 6.22 days of the general population unit. The mortality rate was 37.19% compared to a rate of 27.17% of the population. The primary site of infection was the respiratory tract with 41.3% followed by infection of the bloodstream with 27.27%. The initial average of bacterial resistance related of P. aeruginosa was close to 50% and A. baumannii was greater than 80%, with no significant modifications to the P. aeruginosa in this period. There was a significant increase in resistance to A. baumannii to amikacin. Consumption of antimicrobial agents showed an increase of antimicrobials amikacin, imipenem and piperacillin-tazobactam in cases of infection by P. aeruginosa infections and imipenem in A. baumannii. No correlation was found between bacterial resistance and antimicrobial consumption. CONCLUSION: Mortality and length of stay were higher in the study group. The bloodstream and respiratory tract were the main sites of infection by A. baumannii and P. aeruginosa multiresistant. The susceptibility profile revealed that P. aeruginosa and A. baumannii are highly resistant to antimicrobials. There were no significant changes in the evolution of antimicrobial resistance to the antibiotics tested, except for amikacin used in infections caused by A. baumannii. The consumption of antimicrobials showed increased consumption of amikacin, imipenem and piperacillin-tazobactam in patients infected with P. aeruginosa and to A. baumannii increased consumption was only to imipenem. The relationship between consumption of antimicrobials and increased bacterial resistance was not identified. / O aumento da resistência bacteriana ocorre em todas as regiões do mundo, principalmente em pacientes graves, internados em unidades de terapia intensiva (UTIs) e que fazem uso de vários antimicrobianos. A resistência bacteriana dificulta a terapia, prolonga a permanência nas UTIs e aumenta a morbimortalidade. Dentre os microrganismos causadores de infecções em UTIs, destacam-se P. aeruginosa e A. baumannii, gram-negativos de alta incidência em infecções hospitalares e que vêm apresentando aumento da resistência aos antimicrobianos. OBJETIVO: Avaliar os aspectos microbiológicos e a resistência bacteriana em UTIs dos agentes P. aeruginosa e A. baumannii. MATERIAL E MÉTODOS: Estudo retrospectivo, de janeiro de 2007 a dezembro de 2010, sobre o perfil de sensibilidade e P. aeruginosa e de A. baumannii em pacientes de UTIs adulto (clínica e cirúrgica) do HC/UFG, com diagnóstico de infecção hospitalar. Analisou-se a evolução da resistência, consumo de antimicrobianos, mortalidade, topografia das infecções e tempo de permanência nas unidades. Foram catalogados 121 casos. RESULTADOS: A média de idade dos pacientes foi 51,2±17,9 anos, sendo 45,45% do sexo masculino e 55,55% do sexo feminino; a média de permanência na UTI foi de 27 dias, comparado com 6,22 dias da população geral da unidade. A taxa de mortalidade foi de 37,19% ante uma taxa de 27,17% da população geral. O principal local de infecção foi a via respiratória com 41,3% seguido pela infecção de corrente sanguínea com 27,27%. A taxa média inicial de resistência bacteriana da P. aeruginosa foi próxima de 50% e A. baumannii foi superior a 80%, não se observando modificações para a P. aeruginosa nesse período. Houve um aumento significativo na resistência para o A. baumannii para amicacina. O consumo de antimicrobianos apresentou aumento dos antimicrobianos amicacina, imipenem e piperacilina-tazobactam nos casos de infecção por P. aeruginosa e imipenem nas infecções por A. baumannii. Não foi encontrada correlação entre a resistência bacteriana e o consumo de antimicrobianos. CONCLUSÃO: A mortalidade e o tempo de permanência foram maiores no grupo em estudo. A corrente sanguínea e o trato respiratório foram os principais sítios de infecção por A. baumannii e P. aeruginosa multirresistentes. O perfil de susceptibilidade revelou que P. aeruginosa e A. baumannii são altamente resistentes aos antimicrobianos testados. Não houve mudanças significativas na evolução da resistência aos antimicrobianos para os antibióticos testados, exceto para a amicacina usada nas infecções por A. baumannii. O consumo de antimicrobianos aumentou para amicacina, imipenem e piperacilina-tazobactam, nos pacientes com infecção por P. aeruginosa e, para A. baumannii o aumento do consumo foi apenas para o imipenem. A relação entre o consumo de antimicrobianos e o aumento da resistência bacteriana não foi identificada.