No description available.

Hospital acquired pneumonia is a major problem in the nosocomial environment worldwide. The rise in the number and level of antibiotic resistant strains of bacteria means that conventional therapies are no longer as effective as they once were. Many of the main causative organisms are Gram-negative rods, such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Haemophilus influenzae and one that has become a greater problem in the last twenty years Acinetobacter genospecies 13 TU. Lipopolysaccharide (LPS) is a molecule that is found on the cell surface of all Gram-negative organisms. LPS is a vital part of the outer membrane of Gram-negative bacteria and is a major factor in these organisms’ ability to cause serious infection and disease. While many Gram-negative organisms, such as E. coli and Klebsiella pneumoniae, are well characterised, other species that have become potential nosocomial pathogens more recently, such as Acinetobacter genospecies 13 TU, are much less well characterised. It is unknown as to how widespread exposure to Acinetobacter genospecies 13 TU is in a healthy population. Also, little is also about pathogenesis of Acinetobacter genospecies 13 TU such as the capacity for induction of cytokines by the Acinetobacter genospecies 13 TU LPS LPS was extracted with the aqueous phenol method and re-purified by Voegel’s method from eight strains of Acinetobacter genospecies 13 TU, four strains of Haemophilus influenzae, two strains of Pseudomonas aeruginosa, two strains of Klebsiella pneumoniae and two strains of E. coli. These LPSs were used in enzyme linked immunosorbant assays (ELISAs) with serum taken from 475 blood donors from the Southeast Scotland Blood Transfusion Service. The results from the ELISAs were averaged for each individual blood donor across all the species tested. These averaged results were compared across the species. LPS from two strains of each species, ten in all, were used to challenge the THP-1 human monocytic cell line and the mRNA was extracted and used in quantitative polymerase chain reactions to measure cytokine induction. It was seen that exposure to Acinetobacter genospecies 13 TU LPS is about as widespread in a healthy population from Southeast Scotland as exposure to Pseudomonas aeruginosa LPS and somewhat similar to Klebsiella pneumoniae LPS. Antibodies to E. coli LPS and Haemophilus influenzae LPS were similarly widespread in a healthy population from Southeast Scotland. These last two were much more widely spread than the other organisms tested. Some individuals seem to produce antibodies at high levels to all of the LPSs tested. It may be possible to use serum from these individuals to make a hyper-immune immunoglobulin preparation to be used in the immunotherapy of hospital associated pneumonia. The LPS from one of the strains of Acinetobacter genospecies 13 TU was able to induce similar levels of cytokine production as Klebsiella pneumoniae and Pseudomonas aeruginosa. It was able to induce higher levels of cytokine production over a greater number of cytokines than both Haemophilus influenzae and E. coli LPS. LPS from the other strain of Acinetobacter genospecies 13 TU tested induced lower levels of cytokines compared to the other strain. These levels were lower than those developed by Haemophilus influenzae and E. coli LPS as well as those induced by the LPSs from Klebsiella pneumoniae and Pseudomonas aeruginosa. It seems that there is a range of different levels of cytokine production induced by Acinetobacter genospecies 13 TU LPS with some strains inducing high levels and others inducing low levels of cytokines.

The role of specific amino acid residues in β-ketoadipate succinyl-coenzyme A transferase II from Acinetobacter calcoaceticus was investigated. A 1412 base pair BamiHI-EcoRI fragment carrying the catIJ genes was amplified by polymerase chain reaction and inserted into pUCl9 to generate the plasmid pCATEl9. Escherichia coli DH5α (pCATEl9) carrying only the catlJ genes expressed 3-fold higher enzyme activity than the parent strain. Two mutants were constructed by site directed mutagenesis so that glutamate was replaced by a glutamine at positions Gln155 and Gln193 in the ß subunit of the primary amino acid sequence of the CoA transferase. Both mutants produced transferase that was catalytically active suggesting that Glu155 and Glu193 do not participate directly in catalysis.

No description available.

No description available.

Acinetobacter baumannii is a Gram-negative, non-fermenting bacillus that has developed into an important nosocomial pathogen, affecting millions of patients worldwide. The widespread ease of transmission, and ability to become multidrug resistant are some of the characteristics that, at the present time, have developed this bacterium into one of the most significant nosocomial pathogens today. The special ability it exhibits in developing resistance to a wide variety of known antimicrobial agents also helped make this a pathogen of profound importance in modern day medical microbiology. Carbapenems are used as a last resort for treating patients infected with resistant or multi-drug resistant (MDR) Acinetobacter baumannii. Hospitals have long served as reservoirs for the transmission of pathogenic bacteria, and this has become a problem in Kuwait. Unfortunately, very little research has been devoted exclusively to investigating Acinetobacter baumannii prevalence, resistance and pathogenicity in Kuwaiti Hospitals. Research on the local population in Kuwaiti Hospitals is important and beneficial to physicians, to help better diagnose and treat the infections, and prevent any outbreaks from spreading. Aim: This study aimed to examine the resistance and identify the genotypic changes in the organism as it spreads through Mubarak Al-Kabeer Hospital. Methods: A total of 88 Acinetobacter baumannii samples were collected from the Mubarak Al- Kabeer Hospital, over a three year period, 2006-2008, and they were identified phenotypically, by Vitek-2 systems, and then genotypically by PCR amplification of blaOXA-51-like gene. The resistance to the carbapenems: imipenem and meropenem, was identified by use of the Minimal Inhibitory Concentration (MIC) test. Pulsed field gel electrophoresis (PFGE) was used to type the strains and classify them into clonal groups. Identification of the blaOXA-51-like gene types of each of the isolates was done via gene sequencing. Results: All 88 isolates were identified as Acinetobacter baumannii by Vitek-2 system and were shown to carry a blaOXA-51-like gene. Resistance to Imipenem was found in 31.8% of the isolates, whereas resistance to meropenem was found in 23.8% of the isolates. Overall carbapenem resistance was observed in 55.7% of the total isolates, with a slight increase in resistance of isolated over the 3 years of collection. In all, there were 10 different blaOXA-51-like genes identified. The sequences of these genes suggested there was some degree of real-time evolution of the blaOXA-51-like genes during the study period. There were four main clonal clusters. There were three main European clones (blaOXA-66, blaOXA-69, and blaOXA-71) plus a new clone with blaOXA-51-like genes with sequences clustered around the blaOXA-98 gene. Conclusion: This study has shown four major clones were found in the hospital during the study period, three of the clones were closely associated with those found in Europe and elsewhere in the world, and one new clone, containing a blaOXA-98-like gene that appears to be more prevalent in this part of Asia. The gradual increase in resistance to carbapenems over the study period warrants further attention and study of this resilient bacterium.

Thèse (M.Sc.)--Université Laval, 2006. / Titre de l'écran-titre (visionné le 18 sept. 2007). Bibliogr.

Multidrug-resistant (MDR) Acinetobacter baumannii have caused nosocomial infections worldwide. Nowadays, there are no effective regimens to treat MDR- A. baumannii. Therefore, this study’s objective was to find out an effective antimicrobial combination against MDR-A. baumannii. This project consisted of four parts. Part 1 was an in vitro antimicrobial susceptibility test of MDR-A. baumannii collected from Thailand. Minimum inhibitory concentrations (MICs) were performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines using a broth microdilution technique. This study found that colistin was the most active against MDR-A. baumannii (MIC50 0.5µg/mL, MIC90 1µg/mL). In addition, 77% of MBL -producing A. baumannii were reported using the MBL Etest strips. This prevalence was higher than previously reported. Part 2 was conducted to compare antimicrobial susceptibility profiles of pre- and post-colistin exposure A. baumannii isolates. After colistin exposure, A. baumannii isolates became resistant to colistin but more susceptible to cefepime, doxycycline, meropenem and rifampicin. These findings suggested the potential of a synergistic activity of colistin combinations. Part 3 was a time-kill study that compared activity of colistin alone and in combination against MDR-A. baumannii. Time-kill assays were performed using a standard inoculum. Colistin monotherapy was rapidly bactericidal against these isolates; however, regrowth occurred at 24 hrs. On the other hand, colistin in combination with cefepime, doxycycline, meropenem or rifampicin demonstrated synergy and maintained bactericidal activity over 24 hrs (100%). Part 4 was designed to optimize meropenem dosing regimens using a PK-PD model. Three MDR-A. baumannii with colistin MICs (0.5-1µg/mL) and meropenem MICs (32-128µg/mL) were tested. The antimicrobial regimens alone and in combination evaluated were: colistin 2.5mg/kg every 12 hrs, meropenem 3g and 6g continuously infused (CI) over 24 hrs. Colistin monotherapy was rapidly bactericidal but regrowth did occur. Both combinations express synergy (100%). Nevertheless, colistin and high dose meropenem (6g CI over 24 hrs) was bactericidal and prevented regrowth over 24 hrs. In conclusion, MBL-producing A. baumannii is more prevalent than previously thought and colistin combined with a high dose meropenem (6g/day) has good potential to overcome multidrug- and carbapenem-resistant A. baumannii. These findings should be further evaluated in animal models and clinical practices. / text

No description available.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Farmácia, Florianópolis, 2016 / Made available in DSpace on 2016-09-20T04:54:48Z (GMT). No. of bitstreams: 1 340467.pdf: 1807485 bytes, checksum: f661f353f7a43a9bf68f0e8de9381343 (MD5) Previous issue date: 2016 / Acinetobacter spp., especialmente A. baumannii é um patógeno oportunista que causa infecções relacionadas à assistência à saúde (IRAS) no mundo todo, com alta morbidade e mortalidade. Infecções causadas por A. baumanni multidroga resistente (MDR) têm aumentado e preocupado os hospitais na escolha da terapia adequada para esses pacientes. O mecanismo mais comum de resistência aos carbapenêmicos em A. baumannii é a degradação enzimática por carbapenemases, como as Beta-lactamases da classe A, Metalo-Beta-lactamase (MBL) e oxacilinases. Neste estudo foram identificados e caracterizados Acinetobacter spp. de um Hospital Universitário (HU-UFSC, Florianópolis/SC, Brasil), isolados entre março e setembro de 2015, coletados de profissionais da saúde, pacientes e superfícies de alto contato de cinco alas do hospital: emergência (EMG), Unidade de terapia intensiva (UTI), Centro cirúrgico (CC), Clínica cirúrgica (CR1) e Clínica médica I (CMI). A identificação e o TSA (Teste de suscetibilidade aos antimicrobianos) foram determinados pelo sistema automatizado (Vitek2®; bioMérieux). Espécies foram também identificadas por sequenciamento do 16S rDNA. A presença de 17 genes foi detectada por qPCR: blaOXA-51-like, blaOXA-58-like, blaOXA-23-like, blaOXA-72-like, blaOXA-143-like, blaOXA-48-like,blaIMP, blaVIM e blaSHV, blaKPC, blaSHV, blaNDM, blaGES, blaCTXM-1, blaCTXM-2, blaCTXM-8, blaCTXM-9. Das 1.430 amostras coletadas, obtivemos 575 isolados, dessas, 140 eram Acinetobacter spp. e 70,7% eram MDR (com 96,9% de resistência aos carbapenêmicos). A detecção dos genes de resistência mostrou que 73,5% das amostras foram positivas para OXA-23, 77,8% para OXA-51 e 2,1% para SHV e CTXM-8. Alguns isolados de Acinetobacter spp. com genes de resistência foram encontrados nas salas de lanches, passante, sala de repouso da enfermagem e nas mãos dos profissionais da saúde. Curiosamente, foram encontrados isolados sensíveis aos cabapenêmicos, mas com genes de resistência para carbapenemases (OXA-23). O teste rápido Blue-Carba, que detecta bactérias produtoras de carbapenemases, mostrou 100% de sensibilidade e especificidade quando comparado ao qPCR. Através do Rep-PCR, 23 perfis diferentes de bandas foram encontrados, quatro desses constituídos exclusivamente por isolados resistentes aos carbapenêmicos, tendo um perfil prevalente com 58 dos isolados (41%). A porcentagem de similaridade global dos 23 perfis foi de 70%. Esses resultados evidenciam alguns pontos críticos no hospital e mostram que uma detecção rápida das bactérias, com genes de resistência circulantes e dos perfis genéticos existentes no hospital, podem orientar condutas para a redução das taxas de IRAs. <br> / Abstract : Acinetobacter spp., particularly A. baumannii, is an opportunistic pathogen that causes healthcare-associated infections (HAI) worldwide with high morbidity and mortality. Infections by A. baumannii multidrug-resistant (MDR) have increased and worried hospital institutions to figure out the appropriate treatment for these patients. The most common mechanism of resistance to carbapenems in A. baumanii is enzymatic degradation by carbapenemases, such as Class A Beta-lactamases, Metallo-Beta-lactamase (MBL) and Oxacilinases. In this study, we identified and characterized Acinetobacter spp. from a University Hospital (HU-UFSC, Florianópolis/SC, Brazil) isolated in Mar-Sep-2015, from healthcare workers, patients and high-touch surfaces at 5 hospital units: Emergency (EMG), Intensive Care (ICU), Surgical Center (SC), Surgical Inpatient (SIU) and Medical Inpatient (MIU). The identification and the AST (antimicrobial susceptibility test) were determined by an automated method (Vitek2®; bioMérieux). Species were also identified by 16S rDNA sequencing. The presence of 17 resistance genes was tested by qPCR: blaOXA-51-like, blaOXA-58-like, blaOXA-23-like, blaOXA-72-like, blaOXA-143-like, blaOXA-48-like, blaIMP, blaVIM e blaSHV, blaKPC, blaSHV, blaNDM, blaGES, blaCTXM-1, blaCTXM-2, blaCTXM-8, blaCTXM-9. From the 1,430 samples collected, we obtained 575 strains, out of these, 140 were Acinetobacter spp. and 70.7% were MDR (being 96.9% of these resistant to carbapenems). The detection of resistance genes showed that 73.5% of strains were positive for OXA-23, 77.8% for OXA-51 e 2.1% para SHV e CTXM-8. Some of A. baumanni with resistance genes were found in the snack room, on a patient bed transfer board, nurse´s station and hands of healthcare workers. Interestingly, we found Acinetobacter spp. sensitive to carbapenems with carbapenem resistance genes (OXA-23). The rapid test Blue-Carba, which detects strains producing carbapenemases, showed 100% of sensitivity and specificity comparing to qPCR. Rep-PCR revealed 23 different profiles (four composed of strains resistant to carbapenems), being one prevalent with 58 isolates (41%). The global percentage of similarity of these profiles was of 70%. These results highlight some critical points found in the hospital and show that a rapid detection of strains with resistance genes and the genetic profiles circulating in the hospital, may contribute in the conduits for the reduction of hospital infection.