ABSTRACT
Background: Acinetobacter baumannii has emerged as an important nosocomial pathogen, its ability to acquire resistance to carbapenems and aminoglycosides, has complicated their treatment regimen. The present study investigates the prevalence and diversity of aminoglycoside-modifying enzymes and 16S methyltransferases in A. baumannii isolates recovered from patients admitted in Intensive Care Unit (ICU) of a tertiary referral hospital in Northeastern India. Materials and Methods: We investigated the high-level aminoglycoside-resistance (HLAR) (gentamicin and amikacin minimum inhibitory concentration ? 512 ?g/ml) among 164 multidrug-resistant A. baumannii obtained from ICU. Genes encoding aminoglycoside-modifying enzymes, 16S methyltransferase and coexisting beta-lactamases were amplified. Horizontal transferability, plasmid stability and elimination assays were performed. Clonality and sequence types were evaluated by repetitive extragenic palindromic-polymerase chain reaction and multilocus sequence typing (MLST) respectively. Results: A total of 130 (79.2%) isolates were found to exhibit HLAR, with acquired aminoglycoside-resistance genes in 109 (83.8%) isolates along with coexisting extended-spectrum beta-lactamases and metallo-beta-lactamases. Genes aph (3') I, aph (3') VIa and armA were predominant and horizontally transferable. Plasmids were eliminated with single sodium dodecyl sulphate treatment. Seventeen haplotypes were found responsible for the infection. MLST revealed circulation of ST583 and ST188 in ICU. Conclusions: This study reveals the presence of aminoglycoside-resistance genes in combination with blaCTXM and blaNDM, which are highly stable and not frequently reported from this geographical region. Further, the study could predict limited treatment option and need for formulating infection control strategy.
ABSTRACT
The North Eastern region of India is undergoing industrial development at a faster rate than expected. Roads form the main system of transportation and communication owing to the hilly topography of the region. Automobiles discharge a number of gaseous and trace metal contaminants. Human activities like stone grinding, road construction and sand milling also increase the atmospheric dust and heavy metal contaminant level. These contaminants get settled on leaf surfaces at roadsides and enter in contact with phylloplane microorganisms. This study compares microorganisms on leaf surfaces of alder (Alnus nepalensis (Betulaceae)) on roadside and non-roadside environments. Two sites dominated by alder were selected. One at a busy road intersection on the National Highway no. 44 in Shillong with high traffic density (8 000-9 000 heavy vehicles/day), taken as the polluted site and the other one in a forest approximately 500 m away from the roadside considered as the unpolluted site. Analysis of phylloplane microorganisms, lead, zinc, copper, cadmium and sulphur was carried out from leaves. The bacterial population was higher at the unpolluted site. Bacterial population showed a significant negative correlation with lead, zinc, copper, cadmium and sulphur. Similarly, fungal population was higher at the unpolluted site. A total of 29 fungal species were isolated from the phylloplane of A. nepalensis (polluted site 16 species; unpolluted site 28 species). Some fungal forms like Mortierella sp., Fusarium oxysporum and Aureobasidium pollulans were dominant in the polluted site. Numbers of phylloplane fungi and bacteria were significantly reduced in the polluted site. The correlation coefficient indicated a detrimental effect of metals like lead, zinc, copper, cadmium and sulphur on the microbial community of leaf surfaces. The specificity of certain fungi to the unpolluted site may be attributed to their sensitivity to pollution. The predominance of Aureobasidium pollulans, Fusarium oxysporum and Mortierella sp. in the polluted site may be due to their resistance to pollutants in roadside conditions. Rev. Biol. Trop. 56 (3): 1521-1529. Epub 2008 September 30.
La región nororiental de la India está experimentando un rápido desarrollo industrial y debido a la topografía montañosa de la región, los automóviles descargan variedad de contaminantes. Actividades humanas como moler piedra y construir caminos también aumentan el polvo atmosférico y la contaminación con metales pesados. Este estudio compara microorganismos en superficies foliares del árbol Alnus nepalensis (Betulaceae). Se estudió uno sitio en una intersección de Shillong, con alta densidad de tráfico (8 000-9 000 vehículos pesados/día), tomada como el sitio contaminado, y otro en un bosque aproximadamente a 500 m de la carretera (sitio no contaminado). Se contabilizaron bacterias, hongos, plomo, zinc, cobre, cadmio y sulfuro. La población bacteriana era más alta en el sitio no contaminado. La población bacteriana mostró una correlación negativa significativa con el contenido de plomo, cinc, cobre, cadmio y sulfuro foliares en el sitio contaminado, mientras que en el sitio no contaminado la correlación fue insignificante. La población de hongos también fue más alta en el sitio no contaminado. Un total de 29 especies de hongos fueron aislados A. nepalensis: 16 en el sitio contaminado y 28 en el no contaminado. Algunas especies de hongos como Mortierella sp., Fusarium oxysporum y Aureobasidium pollulans fueron dominantes en el sitio contaminado. El número de hongos y bacterias fue significativamente menor en el sitio contaminado. El coeficiente de correlación indicó un efecto perjudicial de metales como el plomo, el zinc, el cobre, el cadmio y el sulfuro en esta comunidad que habitan superficies de hojas. La especificidad de ciertos hongos al sitio no contaminado se puede atribuir a su sensibilidad a la contaminación. El predominio de Aureobasidium pollulans, Fusarium oxysporum y Mortierella sp. en el sitio contaminado puede ser debido a su resistencia a los agentes contaminadores.