Population structure of Pseudomonas aeruginosa through a MLST approach and antibiotic resistance profiling of a Mexican clinical collection.

Pseudomonas aeruginosa is one of the most important pathogens worldwide. Population genetics studies have shown that the P. aeruginosa population has an epidemic structure with highly conserved clonal complexes. Nonetheless, epidemiological studies of P. aeruginosa have been historically absent or infrequent in developing countries, in which different medical treatments, conditions and infrastructure may have an impact in population dynamics and evolutionary outcomes, including antibiotic resistance profiles. In this study we contribute to fill this gap by analyzing 158 P. aeruginosa isolates from the most extensive nosocomial collection in Mexico City. We investigated the population genetic structure through a MLST approach together with a classical microbiology antibiotic resistance profiling, one of the associated concerns in the evolution of this pathogen. On the one hand, our results are in accordance with previous studies on the epidemic structure of P. aeruginosa, as well as the existence of three main phylogroups, that are not related to environmental parameters. On the other hand, antibiotic resistance profiles indicate higher prevalence in our sample of multi drug resistant (75.15%), extremely drug resistant (17.72%) and pan-drug resistant (9.49%) than resistance reported in developed countries. It is important to reflect on the causes that make less developed countries hotspots of antibiotic resistance, considering the multifactorial aspects of the socio-political context of such countries that include, but are not restricted to, public policy implementation and enforcement regarding access to antibiotics, as well as health care personnel education and other obstacles related to poverty and unequal access to health services and information.

Induction chemotherapy followed by supracricoid partial laryngectomy (SCPL) with cricohyoidoepiglottopexy (CHEP) in T3NO arytenoid fixation-related glottic cancer.

Induction chemotherapy followed by supracricoid partial laryngectomy (SCPL) with cricohyoidoepiglottopexy (CHEF) in T3NO arytenoid fixation-related glottic cancer. OBJECTIVE: Arytenoid fixation in the larynx has been considered a contraindication for performing organ preservation surgery (OPS). We present a retrospective series of cases of arytenoid fixation-related T3N0 glottic cancer treated by neoadjuvant chemotherapy followed by OPS. MATERIAL: Retrospective review of 19 patients (from 2008 to 2012) with T3NO glottic cancer who received two cycles of neoadjuvant chemotherapy with a combination of paclitaxel, cisplatin and 5-fluoruracil (PPF), with a 21-day interval between each cycle, followed by supracricoid partial laryngectomy (SCPL) with cricohyoidoepiglottopexy (CHEP). RESULTS: Sixteen patients with a mean age of 56.4 years received neoadjuvant chemotherapy with a clinical response (7 partial response/9 complete response) and radiologic response by computed tomography (CT) (7 partial response/7 complete response/2 cases without CT) were treated with SCPL-CHEP and removal of the arytenoid cartilage in the tumour site (10 left/6 right), bilateral neck dissection of levels II to V and searching of the Delphian node. There was one patient who died after a recurrence in the larynx and who also had an additional concomitant second primary tumour, and a second patient with a second primary tumour in the lung, who is still alive after treatment. Disease-free survival (DFS) was 82.5% at 5 years and overall survival (OS) was 80% at 5 years. CONCLUSION: Neoadjuvant chemotherapy proved beneficial in patients waiting for surgery, helped maximize the oncologic benefit of the surgery provided (good local control using SCPL with CHEP), improved regional and distant control, minimized side effects by avoiding treatment with radiotherapy whenever possible, and proved feasible even in the presence of ipsilateral arytenoid fixation. Our results are encouraging, although a multi-centre randomized clinical trial should be performed in order to identify the true impact of this approach.

Alternating chemotherapy: gemcitabine and cisplatin with concurrent radiotherapy for treatment of advanced head and neck cancer.

BACKGROUND: Many studies have shown gemcitabine and cisplatin are radiosensitizers. Concurrent chemoradiation seems to be an efficient approach for treatment of advanced head and neck cancer (HNC), but toxicity is significant. OBJECTIVE: To evaluate safety and explore efficacy of alternating chemotherapy with gemcitabine and cisplatin concurrent with radiotherapy in patients with advanced non-metastatic HNC. PATIENTS AND METHODS: Twenty-eight patients diagnosed with advanced Squamous Cell Carcinomas of the Head and Neck (SCCHN) in stages III (28%), IVa (36%), and IVb (36%) were treated with gemcitabine: 100mg/m(2) alternating with cisplatin: 50mg/m(2) concurrent with radiotherapy at doses of 2 Gy/day until completing 70 Gy. While awaiting for concurrent treatment, eleven patients received induction chemotherapy with cisplatin: 100mg/m(2) and 5-FU: 1000 mg/m(2). Toxicity, especially in relation to mucositis, xerostomy, dysphagia, leucopenia and radiodermitis was evaluated. RESULTS: 5-year progression-free survival was 27.8 ± 17.2% (CI-95: 0-61.5) and overall survival was 55.9 ± 11% (CI: 34.4-77.5). Overall response rate was 93%; complete response was 64.3% and partial response was 28.6%. Extensive surgery for primary site was avoided in 19 patients (70.4%). Grade 3-4 adverse events were mucositis (46.4%), leucopenia (14.2%), dysphagia (25%), xerostomy (10.7%) and radiodermitis (3.6%). Response rates and toxicity were not significantly different among those patients with and without induction chemotherapy, but survival was higher in patients receiving induction. CONCLUSIONS: Gemcitabine alternating with cisplatin concurrent with radiotherapy is an active and safe treatment that deserves further study.