Resistant Strains Of Acinetobacter Research Articles

Synthesis and investigation of binding interactions of 1,4-benzoxazine derivatives on topoisomerase IV in Acinetobacter baumannii

Acinetobacter baumannii has emerged as an important pathogen for nosocomial infections having high morbidity and mortality. This pathogen is notorious for antimicrobial resistance to many common antimicrobial agents including fluoroquinolones, which have both intrinsic and acquired resistance mechanisms. Fluoroquinolones targeting the bacterial topoisomerase II (DNA gyrase and Topo IV) show potent broad-spectrum antibacterial activity by the stabilization of the covalent enzyme–DNA complex. However, their efficacy is now being threatened by an increasing prevalence of resistance. Fluoroquinolones cause stepwise mutations in DNA gyrase and Topo IV, having alterations of their binding sites. Furthermore, the water–Mg+2 bridge, which provides enzyme–fluoroquinolone interactions, has a significant role in resistance. In this study, 13 compounds were synthesized as 1,4-benzoxazine derivatives which act as bacterial topoisomerase II inhibitors and their antibacterial activities were determined against multi-drug resistant Acinetobacter strains which have ciprofloxacin (CIP) resistant and GyrA mutation. Afterwards we performed docking studies with Topo IV (pdb:2XKK) of these compounds to comprehend their binding properties in Discovery Studio 3.5. The results of this study show significant conclusions to elucidate the resistance mechanism and lead to the design of new antibacterial agents as bacterial topoisomerase II inhibitors.

Prevalence of Metallo-β-Lactamases ProducingAcinetobacter baumanniiin a Moroccan Hospital

Objective. To determine the prevalence of metallo beta-lactamases (MBL) among carbapenem resistant strains ofAcinetobacter baumanniiin our hospital.Methodology. During a period of 12 months (January–December 2010), 47 isolates ofAcinetobacter baumanniiwere collected from different clinical specimens of in-patients. Antimicrobial susceptibility was determined and interpreted using the disk diffusion method according to the Antibiogram Committee of the French Society for Microbiology guidelines. Imipenem nonsusceptible isolates were further screened for production of MBL.Results. AllAcinetobacter baumannii’ isolates were resistant to ticarcillin, ticarcilline/clavulanate, piperacillin, piperacillin/tazobactam, gentamicin, tobramycin, and ciprofloxacin, except an isolate that was sensitive to ceftazidime and cefepime. In addition to that, amikacin and trimethoprim/sulfamethoxazole were, respectively, sensitive by 59.5% and 53%. Among 57,4% (27/47) imipenem non-susceptible isolates ofAcinetobacter baumannii, 74% (20/27) were found to be MBL producers.Conclusion. Although the rate of imipenem non-susceptible isolates ofAcinetobacter baumanniseems to remain stable in 2005 (57%) and 2010 (57,5%), the prevalence of MBL producer strain is increasing (38% in 2005 versus 75% in 2010). The findings strongly suggest that there is a need to track the detection of MBL producers; moreover, a judicious use of carbapenems is necessary to prevent further spread of these organisms.

Risk Factors for an Outbreak of Multi-Drug-Resistant Acinetobacter Nosocomial Pneumonia Among Intubated Patients

Acinetobacter baumanii is a Gram-negative coccobacillus that is normally a commensal pathogen but can be a nosocomial pathogen. An epidemiologic study was performed to investigate an outbreak of A baumanii that occurred in our medical intensive care unit (MICU) from March to September 1995. A case-control study was performed by retrospective chart review, comparing case patients to randomly selected patients who were mechanically ventilated in the MICU for at least 1 week during the outbreak. A case patient was defined as any patient with an Acinetobacter infection in which the epidemic strain was considered to be a pathogen. The epidemic strain was defined by its antibiogram. Case patients and control patients were compared for age, gender, underlying disease, acute physiology and chronic health evaluation III score, length of MICU stay, prior antibiotic use, presence of fever, sepsis, type of pulmonary infiltrate, and outcome. Environmental and hand-washing studies also were performed during the period of the outbreak. Molecular typing was performed on available bloodstream isolates. There were 15 cases of A baumanii nosocomial pneumonia. Fifty percent were bacteremic; one chart was unavailable for review. Twenty-nine patients were identified as control patients. The mean age for case patients was 50 (range, 21 to 84). The mean duration of time from admission to the ICU to infection was 12.8 days (range, 4 to 40). Sepsis developed in 35% of the case patients. Forty-three percent of the case patients died during their hospitalization, with two of those deaths attributed to Acinetobacter infection. Univariate analysis showed that prior use of ceftazidime was associated with infection with Acinetobacter (11/14 case patients compared to 11/29 control patients; p < 0.01). Pulsed-field gel electrophoresis revealed two strains to be responsible for the outbreak. Hand washing was performed before patient contact by only 10% of health-care workers, and only 32% washed their hands after patient contact. The use of ceftazidime was associated with an increased risk of nosocomial pneumonia with resistant strains of Acinetobacter. Health-care workers need to improve compliance with hand-washing recommendations.

Antibiotic-resistant Acinetobacter meningitis in neurosurgical patients.

Acinetobacter anitratus has emerged as one of the common pathogens responsible for postneurosurgical meningitis at the authors' institution. Seven patients with Acinetobacter meningitis were identified during the 4-year period of this study, five of whom acquired organisms susceptible only to imipenem and amikacin. Acinetobacter bacteremia occurred concomitantly in five patients. Despite late institution of therapy as a result either of organism misidentification on Gram stain or of unexpected acquisition of a highly resistant organism, the patients' outcome was favorable after the initiation of appropriate antibiotic therapy. Imipenem and amikacin, with or without intrathecal aminoglycosides, were effective in patients with resistant strains of Acinetobacter.