Efficacy of tigecycline for secondary Acinetobacter bacteremia and factors associated with treatment failure.

We describe the clinical outcome of 17 patients with secondary Acinetobacter bacteremia whose isolates had a tigecycline MIC of ≤2 mg/liter and who received tigecycline within 2 days of bacteremia onset. The 14-day mortality rate of the tigecycline cohort was 41.2% (7/17), which was significantly higher than that of those receiving other appropriate antimicrobial agents (13.8%, 9/65; P = 0.018). However, the percentages of end-stage renal disease and congestive heart failure were higher in the tigecycline cohort. The efficacy of tigecycline was contingent upon the illness severity and bacterial species. Tigecycline should be applied cautiously for treatment of Acinetobacter bacteremia.

Risk factors and outcomes for patients with bloodstream infection due to Acinetobacter baumannii-calcoaceticus complex.

Identifying patients at risk for bloodstream infection (BSI) due to Acinetobacter baumannii-Acinetobacter calcoaceticus complex (ABC) and providing early appropriate therapy are critical for improving patient outcomes. A retrospective matched case-control study was conducted to investigate the risk factors for BSI due to ABC in patients admitted to the Detroit Medical Center (DMC) between January 2006 and April 2009. The cases were patients with BSI due to ABC; the controls were patients not infected with ABC. Potential risk factors were collected 30 days prior to the ABC-positive culture date for the cases and 30 days prior to admission for the controls. A total of 245 case patients were matched with 245 control patients. Independent risk factors associated with BSI due to ABC included a Charlson's comorbidity score of ≥ 3 (odds ratio [OR], 2.34; P = 0.001), a direct admission from another health care facility (OR, 4.63; P < 0.0001), a prior hospitalization (OR, 3.11; P < 0.0001), the presence of an indwelling central venous line (OR, 2.75; P = 0.011), the receipt of total parenteral nutrition (OR, 21.2; P < 0.0001), the prior receipt of ß-lactams (OR, 3.58; P < 0.0001), the prior receipt of carbapenems (OR, 3.18; P = 0.006), and the prior receipt of chemotherapy (OR, 15.42; P < 0.0001). The median time from the ABC-positive culture date to the initiation of the appropriate antimicrobial therapy was 2 days (interquartile range [IQR], 1 to 3 days). The in-hospital mortality rate was significantly higher among case patients than among control patients (OR, 3.40; P < 0.0001). BSIs due to ABC are more common among critically ill and debilitated institutionalized patients, who are heavily exposed to health care settings and invasive devices.

Sepsis nosocomial en unidad de cuidados intensivos polivalente / Nosocomial sepsis in Multipurpose Intensive Care Units

Introducción: la prevalencia de sepsis nosocomial en las unidades de terapia intensiva es de 20 a 57 casos por 1 000 pacientes/día, por lo que constituye un importante problema de salud. Objetivo: determinar la incidencia de la sepsis nosocomial en una unidad de cuidados intensivos polivalente. Métodos: se realizó un estudio descriptivo, retrospectivo. La muestra quedó constituida por 682 pacientes. Se estudiaron los que durante su evolución presentaron algún tipo de infección nosocomial. Se analizaron los exámenes complementarios, signos clínicos y factores de mal pronóstico. Se tuvieron en cuenta los factores de riesgo asociados con la sepsis. Resultados: desarrollaron sepsis nosocomial 153 pacientes. Predominaron los hombres con un 69,3 por ciento. La media de edades fue de 56 años. El grupo de más de 70 años fue el de mayor incidencia. El 47,06 por ciento de las sepsis fueron de causa clínica. El 66,01 por ciento de los casos desarrollaron infección respiratoria. El 88,20 por ciento presentó factores de mal pronóstico, siendo el más frecuente el aumento de la temperatura por encima de 39 ºC. El 98,04 % de los pacientes tuvieron factores de riesgo de desarrollar sepsis. El Acinetobacter calcoaceticus se aisló en el 33,33 por ciento y la Klebsiella pneumoniae en el 30,07 por ciento.Conclusiones: la mayor cantidad de infecciones nosocomiales fueron de causa clínica. Casi todos los pacientes presentaron elementos de mal pronóstico y los gérmenes más aislados fueron el Acinetobacter calcoaceticus y la Klebsiella pneumoniae(AU)

Introduction: the prevalence of nosocomial sepsis in Intensive Care Units is 20-57 cases per 1000 patients daily what constitutes an important health problem. Objective: to determine the incidence of nosocomial sepsis in a Multipurpose Intensive Care Unit. Methods: a descriptive retrospective study was performed. The sample was composed of 682 patients. The patients under study were those who presented some type of nosocomial infection. Complementary exams, clinical signs and factors predicting a bad prognosis were all analysed. Risk factors associated to sepsis were taken into account. Results: 153 patients developed nosocomial sepsis. It predominated in men who represented a 69.3 percent. The mean age was 56 years. The group over 70 years of age had the highest incidence. The 47.06 percent of sepsis had a clinical cause. A 66.01 percent of the cases developed respiratory infections. The 88.20 percent presented factors that predict a bad prognosis, being the temperature elevation over 39 o C the most frequent one. The 98.04 percent of patients had risk factors to develop sepsis. Acinetobacter calcoaceticus was isolated in a 33.33 percent of the cases and Klebsiella pneumoniae was isolated in the 30.07 percent of the cases as well. Conclusions: the high rates of nosocomial infections had a clinical cause. Almost all patients presented signs predicting a bad prognosis and the most isolated germs were the Acinetobacter calcoaceticus and the Klebsiella pneumoniae(AU)

Antibiotic resistance patterns of Acinetobacter calcoaceticus–A. baumannii complex species from Colombian hospitals

Introduction Only automated phenotypic methods are currently used in Colombian hospitals for identifying isolates of the Acinetobacter calcoaceticus-A. baumannii complex (ACB). The phenotypical similarities in these species mean that they cannot be differentiated by manual or automated methods, thereby leading to their identification as A. baumannii, or ACB complex in clinical settings. Our objective was to identify to the species level 60 isolates, from four hospitals, evaluate their antibiotic susceptibility, and detect resistance-related genes.Methods16S–23S rRNA internal transcribed spacer (ITS) region and rpoB gene partial sequences were amplified. Resistance genes for cephalosporin, carbapenem and aminoglycoside were detected by PCR. Possible mutations in the quinolone resistance-determining region (QRDR) were evaluated. The association of ISAba-1 with blaOXA and blaADC genes was determined by PCR. Amplification products of ITS region, rpoB gene and some resistance genes were sequenced and compared using the BLAST tool. Results: 16S-23S rRNA ITS region and partial rpoB gene sequence analysis allowed 51isolates to be identified as A. baumannii, 8 as A. nosocomialis, and 1 isolate as A. pitti. A. baumannii isolates were highly resistant to all antibiotics tested, while the others were susceptible to ciprofloxacin and ampicillin/sulbactam. Quinolone resistance, found only in A. baumannii, was associated with mutations in the QRDR region of gyrA and parC genes. Conclusion This is the first investigation in Colombia that has identified ACB complex species using molecular methods, and determined differences in antibiotic resistance and resistance genes among the species. It is of the highest importance to identify isolates to the species level for future resistance and epidemiology studies in our region (AU)

Introducción Actualmente, los hospitales en Colombia utilizan únicamente métodos fenotípicos automatizados para la identificación de aislamientos del complejo Acinetobacter calcoaceticus - baumannii (ACB). La similitud entre estas especies no permite que se diferencien por métodos fenotípicos ya sean estos manuales o automatizados, llevando a que los aislamientos se identifiquen como A. baumannii o como pertenecientes al complejo ACB en las instituciones hospitalarias. Nuestro objetivo fue identificar a nivel de especie, 60 aislamientos de cuatro hospitales, identificados como del complejo ACB, evaluar su resistencia a antibióticos y detectar genes de resistencia. Métodos Para la identificación de especies se amplificaron la región intergénica espaciadora de los genes 16S y 23S rRNA y la secuencia parcial del gen rpoB. Estos amplificados y algunos genes de resistencia se secuenciaron y se compararon utilizando la herramienta BLAST. Se detectaron por PCR genes de resistencia a cefalosporinas, carbapenemes y aminoglicósidos. Se evaluaron posibles mutaciones en la región determinante de resistencia a quinolonas (QRDR). Se determinó por PCR la asociación de ISAba-1con los genes blaOXA y blaADC. Resultados Con las secuencias de la región ITS 16S-23S rRNA y el gen rpoB, se identificaron 51 aislamientos (..) (AU)

The success of acinetobacter species; genetic, metabolic and virulence attributes.

An understanding of why certain Acinetobacter species are more successful in causing nosocomial infections, transmission and epidemic spread in healthcare institutions compared with other species is lacking. We used genomic, phenotypic and virulence studies to identify differences between Acinetobacter species. Fourteen strains representing nine species were examined. Genomic analysis of six strains showed that the A. baumannii core genome contains many genes important for diverse metabolism and survival in the host. Most of the A. baumannii core genes were also present in one or more of the less clinically successful species. In contrast, when the accessory genome of an individual A. baumannii strain was compared to a strain of a less successful species (A. calcoaceticus RUH2202), many operons with putative virulence function were found to be present only in the A. baumannii strain, including the csu operon, the acinetobactin chromosomal cluster, and bacterial defence mechanisms. Phenotype microarray analysis showed that compared to A. calcoaceticus (RUH2202), A. baumannii ATCC 19606(T) was able to utilise nitrogen sources more effectively and was more tolerant to pH, osmotic and antimicrobial stress. Virulence differences were also observed, with A. baumannii ATCC 19606(T), A. pittii SH024, and A. nosocomialis RUH2624 persisting and forming larger biofilms on human skin than A. calcoaceticus. A. baumannii ATCC 19606(T) and A. pittii SH024 were also able to survive in a murine thigh infection model, whereas the other two species were eradicated. The current study provides important insights into the elucidation of differences in clinical relevance among Acinetobacter species.

Acinetobacter calcoaceticus-baumannii complex strains induce caspase-dependent and caspase-independent death of human epithelial cells.

We investigated interactions of human isolates of Acinetobacter calcoaceticus-baumannii complex strains with epithelial cells. The results showed that bacterial contact with the cells as well as adhesion and invasion were required for induction of cytotoxicity. The infected cells revealed hallmarks of apoptosis characterized by cell shrinking, condensed chromatin, and internucleosomal fragmentation of nuclear DNA. The highest apoptotic index was observed for 4 of 10 A. calcoaceticus and 4 of 7 A. baumannii strains. Moreover, we observed oncotic changes: cellular swelling and blebbing, noncondensed chromatin, and the absence of DNA fragmentation. The highest oncotic index was observed in cells infected with 6 A. calcoaceticus isolates. Cell-contact cytotoxicity and cell death were not inhibited by the pan-caspase inhibitor z-VAD-fmk. Induction of oncosis was correlated with increased invasive ability of the strains. We demonstrated that the mitochondria of infected cells undergo structural and functional alterations which can lead to cell death. Infected apoptotic and oncotic cells exhibited loss of mitochondrial transmembrane potential (ΔΨ(m)). Bacterial infection caused generation of nitric oxide and reactive oxygen species. This study indicated that Acinetobacter spp. induced strain-dependent distinct types of epithelial cell death that may contribute to the pathogenesis of bacterial infection.

Nosocomial acinetobacter genomic species 13 TU endocarditis following an endoscopic procedure.

We report a rare case of prosthetic valve endocarditis caused by Acinetobacter genomic species 13 TU. This patient had rheumatic heart disease and received prosthetic mitral valve replacement eleven years previously. He was admitted due to tarry stool. Endoscopic procedure showed two gastric ulcers and some mucous breaks at the distal esophagus. He had a fever on the eleventh hospital day. Persistent Acinetobacter bacteremia was noted with conjunctiva hemorrhage. The pathogen was identified as Acinetobacter genomic species 13 TU by PCR-based method. According to his whole course of disease, the most possible portal of entry was via the endoscopic procedure.

An outbreak of multidrug-resistant Acinetobacter baumannii-calcoaceticus complex infection in the US military health care system associated with military operations in Iraq.

BACKGROUND: We investigated an outbreak of multidrug-resistant Acinetobacter baumannii-calcoaceticus complex infection among US service members injured in Iraq. METHODS: The investigation was conducted in Iraq and Kuwait, in the 2 military hospitals where the majority of injured service members were initially treated. After initially characterizing the outbreak, we evaluated 3 potential sources of infection for the period March 2003 to December 2004. The evaluation included screening samples that were obtained from the skin of patients for the presence of colonization and assessing the soil and health care environments for the presence of A. baumanii-calcoaceticus complex organisms. Isolates obtained from samples from patients in US Military treatment facilities, as well as environmental isolates, were genotypically characterized and compared using pulsed-field gel electrophoresis. RESULTS: A. baumanii-calcoaceticus complex organisms were present on the skin in only 1 (0.6%) of 160 patients who were screened and in 1 (2%) of 49 soil samples. A. baumanii-calcoaceticus complex isolates were recovered from treatment areas in 7 of the 7 field hospitals sampled. Using pulsed-field gel electrophoresis, we identified 5 cluster groups in which isolates from patients were related to environmental isolates. One cluster included hospitalized patients who had not been deployed to Iraq. Among the clinical isolates, only imipenem, polymyxin B, and colistin demonstrated reliable in vitro antimicrobial activity. Generally, the environmental isolates were more drug susceptible than were the clinical isolates. CONCLUSIONS: Our findings suggest that environmental contamination of field hospitals and infection transmission within health care facilities played a major role in this outbreak. On the basis of these findings, maintaining infection control throughout the military health care system is essential. Novel strategies may be required to prevent the transmission of pathogens in combat field hospitals.

Changes in antibiotic resistance of the most common Gram-negative bacteria isolated in intensive care units.

We studied the changes in antibiotic resistance of the most common Gram-negative bacteria isolated in the intensive care units at our hospital in 2000 and 2002. Bacterial identification was performed by use of the VITEK 60 analyser, and antibiotic susceptibilities were tested by the VITEK 60 analyser and the disk diffusion agar method. The bacteria isolated most frequently were Pseudomonas aeruginosa (132 strains in 2000 and 106 in 2002), Acinetobacter calcoaceticus (98 and 109 strains, respectively) and Klebsiella pneumoniae (53 and 83 strains, respectively). Acinetobacters presented the highest percentage resistance, with significant increases in resistance to imipenem (15% in 2000 and 67% in 2002) and piperacillin/tazobactam (41% and 72%, respectively). P. aeruginosa presented a significant increase in resistance to all antibiotics, except ceftazidime. A large increase was observed in the resistance of K. pneumoniae to amikacin (from 10% to 50%), ceftazidime (from 80% to 90%) and tobramycin (from 80% to 90%). No imipenem-resistant strains of K. pneumoniae were found.

Peritonitis por acinetobacter calcoaceticus en los pacientes en tratamiento con diálisis peritoneal ambulatoria continua

Se describen 11 casos de peritonitis en pacientes sometidos a diálisis peritoneal ambulatoria continua (CAPD) causados por Acinetobacter calcoaceticus en un grupo de 129 pacientes durante 2784 meses. El Acinetobacter calcoaceticus fue responsable de 6.4 por ciento de los 172 episodios de peritonitis registrados durante el período de seguimiento. Se registraron síntomas sistémicos con fiebre,náuseas, vómito y líquido hemático de dializado en 10 casos. La respuesta al tratamiento fue pobre y en cinco (45 por ciento) fue necesario retirar el catéter de diálisis por la falta de respuesta al tratamiento.En seis casos se demostró la presencia de un segundo germen durante la evolución de la peritonitis por Acinetobacter calcoaceticus, en tres Candida albicans, Hafnia alvei, Pseusomonas aeruginosa y Staphylococcus aureus en un caso cada uno. Los 11 episodios de peritonitis causaron 82 días de hospitalización en siete pacientes. La sensibilidad a los antibióticos fue pobre, ninguno sensible a ampicilina, entre las cefalosporinas sólo la ceftazidima fue eficaz in vitro; la amicacina, latobramicina y las quinolonas, mostraron aceptable cubrimiento contra el Acinetobacter calcoaceticus. Comparativamente con otras peritonitis registradas en el grupo, ésta en promedio más días de hospitalización y retiros de catéter de diálisis por falta de respuesta, siendo superada sólo por la causada por Candida albicans. La asociación con otros gérmenes merece mayor investigación, al igual que se debe tratar de comprender mejor la colonización del orificio de salida del catéter por Acinetobacter calcoaceticus, un germen capaz de producir una peritonitis severa y en muchos casos conduce al paciente a ser retirado del programa de CAPD por falla en el tratamiento

High levels of multiple metal resistance and its correlation to antibiotic resistance in environmental isolates of Acinetobacter.

Forty strains of Acinetobacter were isolated from different environmental sources. All the strains were classified into four genospecies, i.e., A. baumannii (33 isolates), A. calcoaceticus (three isolates), A. junii (three isolates) and A. genospecies3 (one isolate). Susceptibility of these 40 strains to salts of 20 heavy metals and 18 antibiotics was tested by the agar dilution method. All environmental isolates of Acinetobacter were resistant to multiple metal ions (minimum 13 metal ions) while all but one of the strains were resistant to multiple antibiotics (minimum four antibiotics). The maximum number of strains were found to be sensitive to mercury (60% strains) while all strains were resistant to copper, lead, boron and tungsten even at 10 mM concentration. Salts of these four metal ions may be added to the growth medium to facilitate selective isolation of Acinetobacter. Rifampicin and nalidixic acid were the most toxic antibiotics, inhibiting 94.5 and 89.5% of the acinetobacters, respectively. A. genospecies3 was found to be the most resistant species, tolerating high concentrations of all the 20 metal ions and also to a greater number of antibiotics than any other species of Acinetobacter tested. An inhibitory concentration (10 mM) of Ni(2+) and Zn(2+) was observed to inhibit the growth of all of the clinical isolates but allowed the growth of the environmental isolates, facilitating the differentiation between pathogenic and non-pathogenic acinetobacters.