RESUMO
Methicillin-resistant Staphylococcus aureus (MRSA) in health-care settings results in life-threatening infections. We examined the incidence of MRSA at the combat support hospital located at the Ibn Sina Hospital in Baghdad, Iraq. We compiled isolate data from 2005 to 2009 characterizing antibiotic susceptibilities, annual trends, patient populations, infection sites, and hospital locations. Approximately 46.1% of S. aureus were MRSA, with increase in numbers of yearly isolates. MRSA was isolated in higher numbers from U.S. military personnel. Non-U.S. patient isolates displayed higher antibiotic susceptibility compared to U.S. military personnel isolates. Outpatient clinic, forward operating bases, and intermediate care ward 1 isolated the most MRSA. Common isolation sites were wound and skin cultures. Community-acquired MRSA was likely present in 291 out of 303 isolates based on antibiotic susceptibility. Our data suggests that most MRSA were community-acquired with limited nosocomial spread. We recommend increases in combat support hospital molecular lab capability to rapidly identify both MRSA categories.
Assuntos
Infecção Hospitalar/epidemiologia , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Infecções Estafilocócicas/epidemiologia , Antibacterianos/uso terapêutico , Infecção Hospitalar/tratamento farmacológico , Hospitais Militares , Humanos , Incidência , Iraque/epidemiologia , Testes de Sensibilidade Microbiana , Prevalência , Infecções Estafilocócicas/tratamento farmacológico , Estatísticas não ParamétricasRESUMO
Antimicrobial resistance is depleting the pharmacopeia of agents clinically useful against Gram-negative bacilli. As the number of active agents diminishes, accurate susceptibility testing becomes critical. We studied the susceptibilities of 107 isolates of the Acinetobacter baumannii-calcoaceticus complex to amikacin, gentamicin, and tobramycin using disk diffusion, Etest, as well as the Phoenix, Vitek 2, and MicroScan automated systems, and compared the results to those obtained by broth microdilution. Genes encoding aminoglycoside-modifying enzymes (AMEs) were detected by multiplex PCR, and clonal relationships were determined by pulsed-field gel electrophoresis. Tobramycin was the most active aminoglycoside (27.1% of isolates were susceptible). Disk diffusion and Etest tended to be more accurate than the Vitek 2, Phoenix, and MicroScan automated systems; but errors were noted with all methods. The Vitek 2 instrument incorrectly reported that more than one-third of the isolates were susceptible to amikacin (a very major error). Isolates were polyclonal, with 26 distinct strains, and carried multiple AME genes unrelated to the strain type. The presence of the ant(2")-Ia gene was statistically associated with resistance to each aminoglycoside. The AME genotype accounted for the resistance profile observed in a minority of isolates, suggesting the involvement of multiple resistance mechanisms. Hospital pharmacy records indicated the preferential use of amikacin over other aminoglycosides in the burn intensive care unit, where aminoglycoside resistance is prevalent. The resistance in that unit did not correlate with a predominant strain, AME genotype, or total annual aminoglycoside consumption. Susceptibility to tobramycin increased, even though susceptible isolates carried AME genotypes predicting the inactivation of tobramycin. Determination of the relative contribution of multiple concurrent resistance mechanisms may improve our understanding of aminoglycoside resistance in the Acinetobacter baumannii-calcoaceticus complex.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter calcoaceticus/efeitos dos fármacos , Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Erros de Diagnóstico/estatística & dados numéricos , Farmacorresistência Bacteriana , Acinetobacter baumannii/classificação , Acinetobacter baumannii/genética , Acinetobacter calcoaceticus/classificação , Acinetobacter calcoaceticus/genética , Adulto , Técnicas de Tipagem Bacteriana , Genes Bacterianos , Genótipo , Humanos , Testes de Sensibilidade Microbiana , Adulto JovemAssuntos
Hospitais , Comunicação Interdisciplinar , Encaminhamento e Consulta , Guerra , Humanos , TelemedicinaRESUMO
Bacterial transcription activators regulate transcription by making essential protein-protein interactions with RNA polymerase, for example, with region 4 of the σ(70) subunit (σ(70) R4). Rob, SoxS, and MarA comprise a closely related subset of members of the AraC/XylS family of transcription factors that activate transcription of both class I and class II promoters. Recently, we showed that interactions between SoxS and σ(70) R4 occlude the binding of σ(70) R4 to the -35 promoter element of class II promoters. Although Rob shares many similarities with SoxS, it contains a C-terminal domain (CTD) that the other paralogs do not. Thus, a goal of this study was to determine whether Rob makes protein-protein interactions with σ(70) R4 at class II promoters and, if so, whether the interactions occlude the binding of σ(70) R4 to the -35 hexamer despite the presence of the CTD. We found that although Rob makes fewer interactions with σ(70) R4 than SoxS, the two proteins make the same, unusual, position-dependent interactions. Importantly, we found that Rob occludes σ(70) R4 from binding the -35 hexamer, just as does SoxS. Thus, the CTD does not substantially alter the way Rob interacts with σ(70) R4 at class II promoters. Moreover, in contrast to inferences drawn from the co-crystal structure of Rob bound to robbox DNA, which showed that only one of Rob's dual helix-turn-helix (HTH) DNA binding motifs binds a recognition element of the promoter's robbox, we determined that the two HTH motifs each bind a recognition element in vivo.
Assuntos
Proteínas de Ligação a DNA/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/genética , Fator sigma/metabolismo , Ativação Transcricional , Sítios de Ligação , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , RNA Polimerases Dirigidas por DNA/química , RNA Polimerases Dirigidas por DNA/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Regiões Promotoras Genéticas , Ligação Proteica , Fator sigma/química , Fator sigma/genética , Transativadores/genética , Transativadores/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
OBJECTIVE: To determine whether multidrug-resistant (MDR) gram-negative organisms are present in Afghanistan or Iraq soil samples, contaminate standard deployed hospital or modular operating rooms (ORs), or aerosolize during surgical procedures. DESIGN: Active surveillance. SETTING: US military hospitals in the United States, Afghanistan, and Iraq. METHODS: Soil samples were collected from sites throughout Afghanistan and Iraq and analyzed for presence of MDR bacteria. Environmental sampling of selected newly established modular and deployed OR high-touch surfaces and equipment was performed to determine the presence of bacterial contamination. Gram-negative bacteria aerosolization during OR surgical procedures was determined by microbiological analysis of settle plate growth. RESULTS: Subsurface soil sample isolates recovered in Afghanistan and Iraq included various pansusceptible members of Enterobacteriaceae, Vibrio species, Pseudomonas species, Acinetobacter lwoffii, and coagulase-negative Staphylococcus (CNS). OR contamination studies in Afghanistan revealed 1 surface with a Micrococcus luteus. Newly established US-based modular ORs and the colocated fixed-facility ORs revealed no gram-negative bacterial contamination prior to the opening of the modular OR and 5 weeks later. Bacterial aerosolization during surgery in a deployed fixed hospital revealed a mean gram-negative bacteria colony count of 12.8 colony-forming units (CFU)/dm(2)/h (standard deviation [SD], 17.0) during surgeries and 6.5 CFU/dm(2)/h (SD, 7.5; [Formula: see text]) when the OR was not in use. CONCLUSION: This study demonstrates no significant gram-negative bacilli colonization of modular and fixed-facility ORs or dirt and no significant aerosolization of these bacilli during surgical procedures. These results lend additional support to the role of nosocomial transmission of MDR pathogens or the colonization of the patient themselves prior to injury.
Assuntos
Microbiologia do Ar , Farmacorresistência Bacteriana Múltipla , Contaminação de Equipamentos , Bactérias Gram-Negativas/isolamento & purificação , Hospitais Militares , Salas Cirúrgicas , Microbiologia do Solo , Aerossóis , Afeganistão , Antibacterianos/farmacologia , Infecção Hospitalar/etiologia , Infecção Hospitalar/prevenção & controle , Bactérias Gram-Negativas/efeitos dos fármacos , Humanos , Controle de Infecções , Iraque , Unidades Móveis de Saúde , Procedimentos Cirúrgicos Operatórios , Estados Unidos , GuerraRESUMO
INTRODUCTION: Organisms that produce extended-spectrum beta-lactamase (ESBL) are significant causes of infection among deployed service members. These specific organisms have increased resistance to several antibiotics, limiting the choice of therapy for the provider. Currently, the deployed microbiology lab uses, by default, the Siemens NBPC30 panel to identify and measure antibiotic susceptibility of gram-negative organisms. However, when an ESBL is suspected, additional confirmatory testing is performed, during which time the health care provider is forced to use broad spectrum antibiotics to protect the patient from infection. In this study, we evaluated the NBPC30 and NBC41 panels for their ability to rapidly and accurately detect ESBL-producing organisms. METHODS: Identification and antimicrobial susceptibility testing of 79 strains of Enterobacteriaceae isolated from patients treated at Ibn Sina tertiary hospital (Baghdad) were performed using the NBPC30 and NBC41 panels. These results were confirmed using a Kirby-Bauer disk diffusion reference method described by the Clinical Laboratory Standards Institute. Sensitivities and specificities of the panels were determined in relation to this reference method. RESULTS: Sensitivity and specificity of the NBC41 were 96.7% and 89%, while they were 86.7% and 72% for the NBPC30 panel. False positive and false negative rates were higher for the NBPC30 panel. CONCLUSION: Our data shows that the NBC41 panel is superior to the NBPC30 panel in rapidly identifying ESBL-producing organisms. Use of the NBPC41 panel decreases the turnaround time by 24 hours, allowing the provider to more accurately apply appropriate antibiotic therapy. Additionally, the NBPC41 panel provides more useful antibiotic susceptibility results compared to the NBPC30. We recommend use of this panel as a primary identification and susceptibility panel for gram-negative organisms.
Assuntos
Bactérias/enzimologia , Testes de Sensibilidade Microbiana/normas , beta-Lactamases/metabolismo , Técnicas Bacteriológicas/métodos , Enterobacteriaceae/enzimologia , Infecções por Enterobacteriaceae/tratamento farmacológico , Humanos , Guerra do Iraque 2003-2011 , Medicina Militar , Militares , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: Multidrug-resistant (MDR) Acinetobacter baumannii and Pseudomonas aeruginosa have emerged as the causes of nosocomial infections in critically ill patients. OBJECTIVE: To characterize the incidence of these MDR bacteria over time in the military healthcare system, comparing isolates recovered from overseas combat casualties with isolates recovered from local military and civilian patients. METHODS: Retrospective electronic records review of culture and/or susceptibility testing results of patients admitted to a military level I trauma center in San Antonio, Texas, during the period from January 2001 through December 2008. Multidrug resistance was defined as the first isolated organism resistant to 3 or more classes of antimicrobial agents. RESULTS: Over time, the percentage of MDR A. baumannii isolates increased from 4% to 55%, whereas the percentage of MDR P. aeruginosa isolates increased from 2% to 8%. Respiratory tract specimens had a higher percentage of MDR A. baumannii isolates (49%), compared with specimens obtained from blood (30%), wound sites (24%), or urine (19%). No difference in the percentages of MDR P. aeruginosa isolates was observed with regard to source of specimen. The percentage of MDR A. baumannii isolates recovered was higher among patients who had been deployed overseas (52%) than among local patients (20%). When isolates recovered from patients in the burn intensive care unit (53% of MDR A. baumannii isolates) were removed from analysis, the percentage of MDR A. baumannii isolates decreased from 38% to 30% while the percentage of MDR P. aeruginosa isolates remained unaffected. CONCLUSION: The percentage of MDR A. baumannii isolates increased in this facility among combat casualties and among local patients, which indicates nosocomial transmission; however, there was no significant increase in the percentage of MDR P. aeruginosa isolates. Isolated changes in the MDR pathogens within a facility can occur. Possible interventions to limit the spread of these organisms could include implementing aggressive infection control practices, controlling antibiotic use, and using active culture surveillance.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Infecção Hospitalar/epidemiologia , Farmacorresistência Bacteriana , Farmacorresistência Bacteriana Múltipla , Hospitais Militares/estatística & dados numéricos , Pseudomonas aeruginosa/efeitos dos fármacos , Infecções por Acinetobacter/epidemiologia , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/isolamento & purificação , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Infecção Hospitalar/microbiologia , Humanos , Incidência , Testes de Sensibilidade Microbiana , Militares , Infecções por Pseudomonas/tratamento farmacológico , Infecções por Pseudomonas/epidemiologia , Pseudomonas aeruginosa/isolamento & purificação , Texas/epidemiologiaRESUMO
Considerable advancements in shock resuscitation and wound management have extended the survival of burned patients, increasing the risk of serious infection. We performed a 6-year review of bacteria identification and antibiotic susceptibility records at the US Army Institute of Surgical Research Burn Center between January 2003 and December 2008. The primary goal was to identify the bacteria recovered from patients with severe burns and determine how the bacteriology changes during extended hospitalization as influenced by population and burn severity. A total of 460 patients were admitted to the burn ICU with 3507 bacteria recovered from 13,727 bacteriology cultures performed. The most prevalent organisms recovered were Acinetobacter baumannii (780), Pseudomonas aeruginosa (703), Klebsiella pneumoniae (695) and Staphylococcus aureus (469). A. baumannii was most often recovered from combat-injured (58%) and S. aureus the most frequent isolate from local (46%) burn patients. Culture recovery rate of A. baumannii and S. aureus was highest during the first 15 hospital days (73% and 71%); while a majority of P. aeruginosa and K. pneumoniae were recovered after day 15 (63% and 53%). All 4 pathogens were recovered throughout the course of hospitalization. A. baumannii was the most prevalent pathogen recovered from patients with total body surface area (TBSA) burns less than 30% (203) and 30-60% (338) while P. aeruginosa was most prevalent in patients with burns greater than 60% TBSA (292). Shifting epidemiology of bacteria recovered during extended hospitalization, bacteriology differences between combat-injured and local burn patients, and impact of % TBSA may affect patient management decisions during the course of therapy.
Assuntos
Queimaduras/microbiologia , Infecção dos Ferimentos , Adolescente , Adulto , Unidades de Queimados/estatística & dados numéricos , Hospitais Militares , Humanos , Incidência , Pessoa de Meia-Idade , Estudos Retrospectivos , Estados Unidos/epidemiologia , Infecção dos Ferimentos/epidemiologia , Infecção dos Ferimentos/microbiologia , Adulto JovemRESUMO
Infections caused by multidrug-resistant (MDR) pathogens are associated with significant morbidity and mortality in patients with burn injuries. We performed a 6-year antibiotic susceptibility records review from January 2003 to December 2008 to assess the prevalence of MDR isolates by pathogen at the US Army Institute of Surgical Research Burn Center. During the study period Acinetobacter baumannii (780 isolates [22%]) was the most prevalent organism recovered, followed by Pseudomonas aeruginosa (703 isolates [20%]), Klebsiella pneumoniae (695 isolates [20%]), and Staphylococcus aureus (469 isolates [13%]). MDR prevalence rates among these isolates were A. baumannii 53%, methicillin-resistant S. aureus (MRSA) 34%, K. pneumoniae 17% and P. aeruginosa 15%. Two isolates, 1 A. baumannii and 1 P. aeruginosa, were identified as resistant to all 4 classes of antibiotics tested plus colistin. A. baumannii isolates recovered from patients with burns greater than 30% of total body surface area (TBSA) were more likely to be MDR (61%) with no significant difference for P. aeruginosa and K. pneumoniae. A higher proportion of MDR P. aeruginosa isolates were recovered from respiratory specimens compared to blood specimens (24% vs. 9%) while the opposite was true for MRSA (35% vs. 54%). A comparison of A. baumannii recovered during hospitalization days 1-5 and 15-30 revealed higher MDR levels as length of stay increased (48% vs. 75%) while no significant trends were observed for P. aeruginosa and K. pneumoniae. A similar pattern was observed for MDR A. baumannii levels for the facility between 2003 and 2005 and 2006-2008 (39% vs. 70%), with no significant increase in MDR P. aeruginosa and MDR K. pneumoniae. Increasing antibiotic resistance patterns of the most prevalent isolates recovered during extended hospitalization, impact of % TBSA and other clinical parameters may affect empirical antimicrobial therapy and patient management decisions during treatment.
Assuntos
Unidades de Queimados/estatística & dados numéricos , Queimaduras/microbiologia , Farmacorresistência Bacteriana Múltipla , Bactérias Gram-Negativas/isolamento & purificação , Bactérias Gram-Positivas/isolamento & purificação , Infecção dos Ferimentos/microbiologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Hospitais Militares/estatística & dados numéricos , Humanos , Testes de Sensibilidade Microbiana , Prevalência , Estudos Retrospectivos , Estados Unidos/epidemiologia , Infecção dos Ferimentos/epidemiologiaRESUMO
In Escherichia coli, Rob activates transcription of the SoxRS/MarA/Rob regulon. Previous work revealed that Rob resides in three to four immunostainable foci, that dipyridyl and bile salts are inducers of its activity, and that inducers bind to Rob's C-terminal domain (CTD). We propose that sequestration inactivates Rob by blocking its access to the transcriptional machinery and that inducers activate Rob by mediating its dispersal, allowing interaction with RNA polymerase. To test "sequestration-dispersal" as a new mechanism for regulating the activity of transcriptional activators, we fused Rob's CTD to SoxS and used indirect immunofluorescence microscopy to determine the effect of inducers on SoxS-Rob's cellular localization. Unlike native SoxS, which is uniformly distributed throughout the cell, SoxS-Rob is sequestered without an inducer, but is rapidly dispersed when cells are treated with an inducer. In this manner, Rob's CTD serves as an anti-sigma factor in regulating the co-sigma-factor-like activity of SoxS when fused to it. Rob's CTD also protects its N-terminus from Lon protease, since Lon's normally rapid degradation of SoxS is blocked in the chimera. Accordingly, Rob's CTD has novel regulatory properties that can be bestowed on another E. coli protein.