Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water

The use of untreated water for drinking and other activities have been associated with intestinal and extraintestinal infections in humans due to Aeromonas species. In the present study aeromonads were isolated from 48.7% of 1,000 water samples obtained from wells and other miscellaneous sources. Aeromonas species were detected in 45% of samples tested in spring, 34.5% in summer, 48% in autumn and 60% of samples tested in winter. Speciation of 382 strains resulted in 225 (59%) being A. hydrophila, 103 (27%) A. caviae, 42 (11%) A. sobria and 11 (3%) atypical aeromonads. Of 171 Aeromonas strains tested for their haemolytic activity, 53%, 49%, 40% and 37% were positive in this assay using human, horse, sheep and camel erythrocytes respectively. The results obtained indicate that potentially enteropathogenic Aeromonas species are commonly present in untreated drinking water obtained from wells in Libya (this may also apply to other neighbouring countries) which may pose a health problem to users of such water supplies. In addition, ceftriaxone and ciprofloxacin are suitable drugs that can be used in the treatment of Aeromonas-associated infections, particularly, in the immunocompromised, resulting from contact with untreated sources of water

Sequence analysis of 16S rRNA, gyrB and catA genes and DNA-DNA hybridization reveal that Rhodococcus jialingiae is a later synonym of Rhodococcus qingshengii

The results of 16S rRNA, gyrB and catA gene sequence comparisons and reasserted DNA–DNA hybridization unambiguously proved that Rhodococcus jialingiae Wang et al. 2010 and Rhodococcus qingshengii Xu et al. 2007 represent a single species. On the basis of priority R. jialingiae must be considered a later synonym of R. qingshengii .</jats:p

Serotypes, virulence factors, antibiotic sensitivity, beta-lactamase activity and plasmid analysis of Salmonella from children with diarrhea in Tripoli (Libya)

A total of 21 Salmonella strains isolated in Libya (16 from children with diarrhea and 5 from healthy controls) were serotyped and studied for their cell invasive ability, production of cytotoxin, antibiotic susceptibility, β-lactamase activity and plasmid profiles. Eight different serotypes of Salmonella were identified: 6 S. saintpaul , 4 S. wien (1 from control), 2 S. newport , 2 S. muenchen (1 from contr ol), 2 S. typhimurium (1 from control) , 2 S. hadar (1 from control), 2 S. reading (1 from control), 1 S. kottbus . Twenty (95%) were positive in the invasiveness assay using HeLa cells, and all (100%) were negative for cytotoxin production in HT29 cells. More than 40% were resistant to ampicillin, cefalexin, cefam andole, cefoperazone, chloramphenicol, gentamicin, mezlocillin and trimethoprim- sulphamethoxazole and 100% were susceptible to the new quinolones. Most (67%) of the strains harbored plasmids and 43% produced β-lactamase. A strong association was observed between the presence of more than one plasmid, β-lactamase activity, and multiple-resistance to antimicrobial agents and serotypes S. saintpa ul and S. wien . Curing experiments with acridine orange showed that 2 plasmids (33 and 1.4 megadaltons ) might be responsible for the resistance to chloramphenicol and gentamicin. The present study demonstrated that multiple-resistant salmonellae are widesp read in Libya and the resistance is mainly plasmid mediated

A comparison of three indirect methods for estimating understory light at different spatial scales in temperate mixed forests

Three indirect light measurement methods were compared in mixed deciduous and coniferous forests with heterogeneous stand structure: tRAYci — a spatially explicit light model calculating percentage of above canopy light (PACL); LAI-2000 Plant Canopy Analyzer measuring diffuse non-interceptance (D1FN); and spherical densiometer estimating canopy openness (CO). Correlations between the different light variables were analyzed at several spatial scales (at 5 × 5, 10 × 10, 15 × 15, 20 × 20 and 30 × 30 m2 ). Relationships between light variables and the cover of alight flexible plant, blackberry ( Rubus fruticosus agg.), as a potentially sensitive response variable for light conditions were also investigated. LAI-2000 (D1FN) and tRAYci (PACL) seemed the most appropriate for the description of the light environment in the investigated stands. D1FN and PACL had stronger correlations with each other and with blackberry cover than CO. Spatial heterogeneity of light (expressed with coefficient of variation) showed much stronger correlations than mean values both between the methods and between light intensity and Rubus cover. The correlation values between the methods increased towards coarser scales (from 5 × 5 to 30 × 30 m2 ), while the correlation between light intensity and blackberry cover had a maximal response at the scale of 20 × 20 m2 if a lower resolution of light estimation was used, and had also a maximum at smaller scales if the light was calculated for more points per plot by tRAYci. LAI-2000 can be recommended for the comparison of different stands, however, for fine scale description of light conditions of a stand tRAYci seems to be more appropriate