Molecular typing of imipenem-resistant Acinetobacter baumannii-calcoaceticus complex in a Singapore hospital where carbapenem resistance is endemic.

OBJECTIVE: To investigate the molecular epidemiology of carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex isolates in a tertiary care hospital where the prevalence of carbapenem resistance among these organisms is high. DESIGN: The study was a prospective, observational study performed during an 8-month period (May 1 through December 31, 2004). A. baumannii isolates recovered from all clinical samples during the study period were included in the study. Antibiotic susceptibility testing was performed using the disk diffusion method, and all carbapenem-resistant strains were typed by a polymerase chain reaction-based typing method.Setting. An 800-bed hospital in Singapore. RESULTS: More than half of recovered isolates were clonally unrelated, with the remaining isolates grouped into 4 genotypes. CONCLUSIONS: The results of the study suggest that the high prevalence of carbapenem resistance among Acinetobacter organisms in this institution is not caused by the spread of a predominant clone and that other factors may need to be investigated.

Use of sequence-based typing and multiplex PCR to identify clonal lineages of outbreak strains of Acinetobacter baumannii.

Representatives (n = 31) of outbreak strains of Acinetobacter baumannii from five countries fell into three clear groups, designated Groups 1-3, based on their ompA (outer-membrane protein A), csuE (part of a pilus assembly system required for biofilm formation) and bla(OXA-51-like) (the intrinsic carbapenemase gene in A. baumannii) gene sequences. With the exception of the closely related alleles within the Group 1 clonal complex, alleles at each locus were highly distinct from each other, with a minimum of 14 nucleotide differences between any two alleles. Isolates within a group shared the same combination of alleles at the three loci, providing compelling evidence that the outbreak strains investigated belonged to three clonal lineages. These corresponded to the previously identified European clones I-III. Sequence differences among the alleles were used to design multiplex PCRs to rapidly assign isolates belonging to particular genotypes to sequence groups. In the UK, genotypes belonging to the Group 1 clonal complex have been particularly successful, accounting for the vast majority of isolates referred from hospitals experiencing problems with Acinetobacter.

Emergence of resistant Acinetobacter baumannii in critically ill patients within an acute care teaching hospital and a long-term acute care hospital.

BACKGROUND: Acinetobacter baumannii is a gram-negative, coccobacillus found in water and is a significant nosocomial pathogen in hospitals. This report chronicles the appearance in June 2003 of a multidrug-resistant A baumannii (MDR-AB) strain, its dissemination, and interventions used to control it in an acute care hospital (ACH) and long-term acute care facility (LTAC). METHODS: Molecular typing using pulsed-field gel electrophoresis (PFGE) showed that 88 of 99 strains (89%) gave an identical banding designated as clone A. Eight additional isolates were variants of clone A, and 3 isolates were unrelated. RESULTS: A baumannii was isolated from 229 patients between January 2003 and December 2004. Of these patients, 151 (66%) were colonized/infected with MDR-AB. Most isolates were resistant to antibiotics except for imipenem and ampicillin/sulbactam. Isolates included 108 (72%) in the respiratory tract, 32 (21%) in wounds, 6 (4%) in blood, and 5 (3%) in urine. Most isolates were found in the LTAC (70 isolates), ICU step-down (27 isolates), and ICU (26 isolates). CONCLUSION: This epidemiologic history illustrates (1) epidemic clonal spread, (2) target populations, (3) variable monthly prevalence, and (4) intervention outcomes. With intervention, the number of new isolates in the ACH decreased by dedicating an infection control professional to critical care, daily surveillance, isolation of positive MDR-AB patients, universal gloving, and routinely reporting results.

Comportamiento de acinobacter en los procesos infecciosos de los pacientes ingresados al HEALF de enero 2004 a diciembre de 2005 / Acinobacter behavior in the infectious processes of the patients entered the HEALF of January 2004 to December of 2005

El trabajo comportamiento de acinetobacter en los procesos infecciosos de pacientes ingresados al HEALF de enero de 2004- diciembre de 2005, se realizó con el objetivo de conocer el comportamiento de esta bacteria en nuestro medio ya que el acinetobacter ha surgido como un importante microorganismo a nivel intrahospitalario y uno de los mayores problemas de la infecciones producidas por esta bacteria es su tratamiento, por su amplia multiresistencia y por las pocas alternativas terapéuticas disponibles en la actualidad. Dicho estudio es descriptivo, de serie de casos. Para alcanzar este objetivo se estudiaron 452 pacientes a los que se aisló 528 Acinetobacter. Los procesos infewcciosos más frecuentes fueron: Sepsis de Herida Quirúrgica, Neumonías y Traqueóbronquitis. Los servicios más afectados fueron: Medicina Interna y de esta, la sala de UCI (Unidad de cuidados intensivos), Neurocirugía, principalmente lka sala de Neurocirugía Intermedios y cirugía plástica principalmente la sala de quemados. Según los resultados de Antibiogrma se encontró un alto grado de resistencia de la bacteria a los antibióticos disponibles en la Lista Básica de Medicamentos como son: Ceftriazona, Ampicilina, Amikacina, Ceftazidima y en menor grado de resistencia a los Carbapemenes (Imipenem, Meropenem)...>

Unusual genetic heterogeneity of Acinetobacter baumannii isolates in a university hospital in Italy.

BACKGROUND: Acinetobacter baumannii has become an increasingly important nosocomial pathogen, particularly in intensive care units (ICUs). The aim of this investigation was to study the molecular epidemiology of A baumanii in a university hospital in Italy. METHODS: All A baumanii isolates were collected and typed with phenotypic and genotypic methods during a 7-month period. A 1-year prospective surveillance of ICU-acquired infections was performed by using the National Nosocomial Infections Surveillance methodology. RESULTS: A baumanni accounted for 28.4% of all infections and 46.7% of all pneumonia acquired in the ICU, with a nosocomial infection rate of 12.4% or 8 infections per 1000 patient-days. Risk factors for A baumannii acquisition in the ICU were mechanical ventilation and previous use of broad-spectrum antibiotics, whereas administration of carbapenems showed a significant protective effect. Pulsed-field gel electrophoresis of genomic Apa I digests identified at least 5 outbreaks in the ICU caused by 5 different clones, one replacing the other in a well-defined temporal order. CONCLUSIONS: Whereas the sequential temporal cluster of epidemic clones in the ICU is intriguing and requires further research, the clear evidence of cross-contamination of A baumannii isolates involved with infections in the ICU demands extensive preventive efforts.

Relevance of digestive tract colonization in the epidemiology of nosocomial infections due to multiresistant Acinetobacter baumannii.

Fecal colonization with multiresistant Acinetobacter baumannii was evaluated in 189 consecutive patients in intensive care units (ICUs) during two different 2-month periods (October-November 1993 and May-June 1994). Rectal swabs were obtained weekly from admission to discharge from the ICU. Overall, 77 patients (41%) had multiresistant A. baumannii fecal colonization; colonization was detected in 55 (71%) of the patients within the first week of their ICU stay. Clinical infections due to multiresistant A. baumannii occurred more frequently in patients with fecal colonization than in those without fecal colonization (26% vs. 5%, respectively; P < .001). The reinforcement of isolation measures between study periods reduced both the number of fecal carriers of multiresistant A. baumannii (from 52% to 31%; P < .01) and the number of patients with multiresistant A. baumannii infections (from 17% to 11%; no statistical significance). The digestive tract of ICU patients could be an important epidemiologic reservoir for multiresistant A. baumannii infections in hospital outbreaks. Further prospective studies should be undertaken to define the relative significance of digestive tract colonization compared with other body site colonizations.

Nosocomial outbreaks due to amikacin-resistant tobramycin-sensitive Acinetobacter species: correlation with amikacin usage.

Fifty-seven patients in the Val-de-Grâce hospital were infected or colonized with amikacin-resistant, tobramycin-sensitive Acinetobacter spp. between January 1985 and December 1987. This resistance phenotype was attributed to the recently described 3'-O-aminoglycoside phosphotransferase (APH(3')-VI), on the basis of substrate profile and DNA-DNA hybridization, and was mainly encountered in various biotypes of A. baumannii isolated from patients. It was also encountered in saprophytic A. johnsonii isolates from the hands of 11 healthy workers among the medical staff, which provided evidence for the dissemination of an epidemic gene among different biotypes and species of Acinetobacter. A retrospective epidemiological survey showed a significant correlation between amikacin consumption and case incidence in the wards where cross-infection had occurred.

Typing of Acinetobacter calcoaceticus strains isolated from hospital patients by cell envelope protein profiles.

The usefulness of sodium dodecyl sulphate-polyacrylamide gel electrophoresis patterns of cell envelope proteins for classifying strains of Acinetobacter calcoaceticus was studied using 129 isolates from 16 in-patients in a teaching hospital. In 11 patients, all of the isolates from each patient exhibited the same pattern irrespective of the body site or time of isolation. The patterns of the isolates from four other patients were indistinguishable, with the exception of one isolate per patient. In the isolates from one patient five patterns were observed. In several cases isolates from different patients exhibited the same pattern. The relative frequency of some of these patterns was low. Epidemiological data were compatible with the assumption that the concurrent presence of bacteria of these patterns in the patients was the result of cross-infection. For one pattern, which was seen in seven patients, cross-infection could not be substantiated. On the basis of analysis of electrophoretic patterns in combination with epidemiological data on a number of strains it is concluded that cell-envelope protein profiles appear to be a useful aid in studying the dissemination of Acinetobacter in the hospital environment.