Drug sensitivity of bacterial strains isolated from clinical specimens during the years 1987-1988

Sensitivity to selected chemotherapeutics of various bacterial strains was analysed. Bacteria were isolated from the different material collected from patients within 1987-1988, and included: 690 strains of staphylococci, 465 strains of streptococci, 1224 strains of aerobic gram-negative bacilli, and 163 strains of anaerobic micro-organisms. Out of isolated staphylococci, the highest percentage was sensitive to vancomycin, pristinamycin, and fusidic acid. Vancomycin proved the most effective against streptococci followed by chloramphenicol and netilmicin . However, streptococci were highly sensitive to vancomycin within two years whereas their sensitivity to chloramphenicol and netilmicin .     

Drug resistance of 100 clinical strains of Enterococcus spp

The aim of this study was to evaluate the drug susceptibility of 100 Enterococcus spp. strains isolated from patients hospitalized in State Clinical Hospital No 1 in Warsaw. All strains were identified (API 20 STREP) and their susceptibility to antibiotics was tested (ATB STREP) in automatic ATB system. Additionally, PYRase activity, beta-lactamase production (in nitrocefin test), MICs for vancomycin and teicoplanin (E test), HLAR--high level aminoglycoside resistance and susceptibility to vancomycin, teicoplanin, piperacillin and piperacillin/tazobactam (disc diffusion method) were determined. E. faecalis ATCC 29212 was used as the control strain. Fifty E. faecalis, 45 E. faecium, 2 E. casseliflavus, 2 E. durans and 1 E. avium strain were cultured. All strains were PYRase-positive and beta-lactamase-negative. Ten isolates demonstrated intermediate susceptibility to vancomycin (6--E. faecalis and 4--E. faecium). One E. faecalis strain was intermediately susceptible to both glycopeptides. One E. casseliflavus strain showed low-level resistance to vancomycin, but this strain was susceptible to teicoplanin--phenotype Van C. HLAR strains were found among 31 E. faecalis and 40 E. faecium strains. 48 E. faecalis strains were susceptible to piperacillin and 49 to piperacillin/tazobactam. Whereas, 41 E. faecium were resistant to both these drugs. Thirty six per cent of isolates were resistant to penicillin and ampicillin, 73% to erythromycin, 87% to tetracycline, 89% to lincomycin and 56% to nitrofurantoin. Some discrepancies were noticed between the results of different methods applied for susceptibility testing--ATB system, E test and disc diffusion. These discrepancies concerned HLAR detection and susceptibility to glycopeptides determination. The best methods were: disc-diffusion for HLAR detection and E test for determination of resistance to vancomycin and teicoplanin. Increasing resistance to antimicrobial agents is observed in clinical Enterococcus spp. isolates cultured in our laboratory, especially in E. faecium strains. It is necessary to control the dissemination of multiresistant Enterococcus spp. strains in hospital wards.     

Host range susceptibility of Enterococcus sp. strains isolated from diseased turbot: possible routes of infection.

Experiments were conducted to assess the pathogenicity of Enterococcus sp. strains isolated from diseased turbot for several fish species (turbot, salmon, trout, and seabream), as well as for mice. The intraperitoneal injection assays indicated that the tested strains showed host specificity for turbot, with a high degree of virulence (50% lethal dose of 10(4) cells per g of fish). The Spanish Enterococcus sp. isolates were nonpathogenic for the other fish species studied and for mice. The possible routes of infection were determined by bath exposure (with and without prior abrasion of the skin) and by intragastric inoculations with food and feces contaminated with the pathogen. The bath challenges indicated that the Enterococcus isolates were able to overcome the defense mechanisms present on the surface of the turbot only if the skin was abraded prior to the exposure. The antibacterial activities of components of a glycoprotein nature present in the turbot skin mucus are probably responsible in part for the resistance in noninjured fish to infection. On the other hand, we demonstrated the capacity of this pathogen to overcome adverse conditions in the stomachs of fish when associated with food or fecal material, since it is able to establish an infective state and to produce mortalities after 16 to 20 days postingestion. From all of these findings, we can conclude that horizontal transmissions through water and the fecal-oral route are the main avenues of infection of turbot streptococcosis.     

Genetic similarity of vancomycin resistant strains of Enterococcus faecium isolated from clinical specimens

Twenty vancomycin resistant E. faecium strains (VRE) isolated from patients of three different hospital wards in 2005-2008 were examined. The strains originated from patients of intensive therapy, urological and internistic wards. The chosen wards differ significantly in their specificity. In all cases the presence of o vanA and lack of vanB, vanD, vanE and vanG genes and were found. Strains were compared by using RFLP-PFGE, the reference method for molecular typing of VRE. One group including fourteen strains showing similarity higher than 79.5% was distinguished. This group was divided into subgroups. The greatest similarity was found among strains from patients of intensive therapy ward. Two subgroups of strains showing similarity more than 93.3%, of four strains each were identified. The similarity between these two subgroups was 79.5%. Most strains from other two wards showed less than 79.5% similarity and they could be recognised as not related. Only one strain from internal ward and two strains from urologic ward were similar in 82.1 - 86.4% to one of subgroups of strains originated from intensive therapy.     

Non-specific adherence of Enterococcus faecalis strains isolated from healthy voluntaries and infection of urinary tract

Enterococcus faecalis is a component of human and animal gastrointestinal microflora. However, the adhesion is considered to be the key step in the pathogenesis of enterococcal infections and the first step of biofilm formation. We aimed to compare and evaluate adherence of strains considered to be commensal flora (isolated from healthy volunteers) and strains isolated as a pathogen from medical samples in Gdańsk Region The additional aim of this study was to analyze influence of subinhibitory concentration of gentamycin and cAD1 pheromone. Comparison involved 20 strains isolated from healthy voluntaries, 23 strains isolated as etiological agent of urinary tract infection and 16 HLAR strains from other infections. Adherence ability was tasted by turbidymetric method at 550 nm, as o reduction of bacterial inoculum after incubation with hydroksyapatite. Results showed significant difference between commensal and virulent strains as well as between none-inducted and inducted by pheromone. In contrast there was no difference between inducted and non-inducted virulent strains as well as between inducted virulent and inducted not virulent strains. The result shows ability to differentiate this group by non-specific adherence.     

Drug resistance in Vibrio cholerae strains isolated from clinical specimens

Cholera is a serious epidemic and endemic disease caused by the Gram-negative bacterium Vibrio cholerae. SXT is an integrative conjugation element (ICE) that was isolated from a V. cholerae; it encodes resistance to the antibiotics chloramphenicol, streptomycin and sulfamethoxazole/trimethoprim. One hundred seven V. cholerae O1 strains were collected from cholera patients in Iran from 2005 to 2007 in order to study the presence of SXT constin and antibiotic resistance.The study examined 107 Vibrio cholerae strains isolated from cholera prevalent in some Iranian provinces. Bacterial isolation and identification were carried out according to standard bacteriological methods. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) to four antibiotics (chloramphenicol, streptomycin, sulfamethoxazole, and trimethoprim) were determined by broth microdilution method. PCR was employed to evaluate the presence of established antibiotic resistance genes and SXT constin using specific primer sets.The resistance of the clinical isolates to sulfamethoxazole, trimethoprime, chloramphenicol, and streptomycin was 97%, 99%, 99%, and 90%, respectively. The data obtained by PCR assay showed that the genes sulII, dfrA1, floR, strB, and sxt element were present in 95.3%, 95.3%, 81.3%, 95.3%, and 95.3% of the V. cholerae isolates.The Vibrio strains showed the typical multidrug-resistance phenotype of an SXT constin. They were resistant to sulfamethoxazole, trimethoprime, chloramphenicol, and streptomycin. The detected antibiotic resistance genes included dfrA for trimethoprim and floR, strB, sulII and int, respectively, for chloramphenicol, streptomycin, sulfamethoxazole, as well as the SXT element.     

Prevalence of virulece-associated genes of Enterococcus faecalis clinical strains isolated from patients and volunteers

Enterococcus faecalis is an important cause of serious hospitals infections. Several E. faecalis putative virulence determinants have been identified. The aim of our study was to determine the prevalence of virulence factors among 180 strains of E. faecalis isolated from humans from different clinical sources in Poland. Tested strains were investigated for the presence of cylA, cylB, cylM, gelE, asal, esp, efaA and ace by using PCR method. Among all strains ace and efaA were most often detected. However, in opposite to strains obtained from faeces of volunteers, most of clinical strains carried esp (64,4% vs. 28,9%) and cylA (44,4% vs. 20%), cylB (41,5% vs. 20%), cylM (45,2% vs. 20%), respectively. Twenty different virulotype were represented by tested strains. Presence of all tested virulence determinants were the most frequently observed among clinical strains. There was no significant association between virulence factors and clinical source of isolation.     

Two novel species Enterococcus lemanii sp. nov. and Enterococcus eurekensis sp. nov., isolated from a swine-manure storage pit

A polyphasic taxonomic study using morphological, biochemical, chemotaxonomic and molecular genetic methods was performed on six strains of unknown Gram-positive, nonspore-forming, facultative anaerobic coccus-shaped bacteria isolated from a swine-manure storage pit. On the basis of the 16S rRNA, RNA polymerase α-subunit (rpoA) and 60 kDa chaperonin (cpn60) gene sequence analyses, it was shown that all the isolates were enterococci but formed two separate lines of descent. Pairwise 16S rRNA gene sequence comparisons demonstrated that the two novel organisms were most closely related to each other (97.9 %) and to Enterococcus aquimarinus (97.8 %). Both organisms contained major amounts of C_16:0, C_16:1 ω7c, C_16:1 ω7c, and C_18:1 ω7c/12t/9t as the major cellular fatty acids. Based on biochemical, chemotaxonomic and phylogenetic evidence, the names Enterococcus lemanii sp. nov. (type strain PC32^T = CCUG 61260^T = NRRL B-59661^T) and Enterococcus eurekensis sp. nov. (type strain PC4B^T = CCUG 61259^T = NRRL B-59662^T) are proposed for these hitherto undescribed species.     

Denitrification ability of rhizobial strains isolated from Lotus sp.

Ten rhizobial strains isolated from Lotus sp. have been characterized by their ability to denitrify. Out of the 10 strains, the five slow-growing isolates grew well under oxygen-limiting conditions with nitrate as a sole nitrogen source, and accumulated nitrous oxide in the growth medium when acetylene was used to inhibit nitrous oxide reductase activity. All five strains contained DNA homologous to the Bradyrhizobium japonicum nirK, norBDQ and nosZ genes. In contrast, fast-growing lotus rhizobia were incapable of growing under nitrate-respiring conditions, and did not accumulate nitrous oxide in the growth medium. DNA from each of the five fast-growing strains showed a hybridization band with the B. japonicum nirK gene but not with norBDQ and nosZ genes. Partial 16S rDNA gene sequencing revealed that fast-growing strains could be identified as Mesorhizobium loti species and the slow-growers as Bradyrhizobium sp.     

Drug resistance of Enterococcus species isolated from the urogenital system

Despite low virulence of enterococci, they have become important nosocomial pathogens. This has been correlated with the increased use of broad-spectrum antibiotics, particularly cephalosporins. Many strains of enterococci exhibit multiple drug resistance; the most important being high-level resistance (HLR) to penicillin (MIC > 100 mg/l) and gentamicin (MIC > 500 mg/l and 2000 mg/l) and/or streptomycin (MIC > 2000 mg/l). The investigation was performed on 92 strains, isolated from genito-urinary tract and recognised as Enterococcus sp. All strains were obtained from several microbiological laboratories of Gdańsk, Gdynia and Tczew. On biochemical reaction profiles species of enterococci were identified as: E. faecalis (72.8%), E. faecalis varians (9.8%), E. durans (7.6%) and E. faecium (9.8%). The minimal inhibitory concentration (MICs) of penicillin, ampicillin, azlocillin, imipenem, gentamicin, amicacin, ciprofioxacin and vancomycin were determined by the agar dilution method. None of these 92 enterococcal strains was vancomycin resistant. 22.2% of E. faecium and 7.5% of E. faecalis showed high-level resistance to penicillin. None of these strains were produced beta-lactamase. High-level resistance to streptomycin and gentamicin was detected. Both--high-level resistance to streptomycin and gentamicin--were found in 6% E. faecalis; 11.1% E. faecalis varians and 22.2% E. faecium.     

Response to antibiotics of Proteus strains isolated from different types of clinical material

The data on the study of the antibiotic response to 42 Proteus strains isolated from different sources in the hospitals of Kharkov are presented. The isolates belonged to P. mirabilis and P. vulgaris. Many strains were resistant to gentamicin, ampicillin and carbenicillin irrespective of the isolation source. 58.0 and 90.3 per cent of the strains isolated from patients with intestinal infections, 66.6 and 100 per cent of the strains isolated from patients with otitis, 33.3 and 66.6 per cent of the strains isolated from patients with bronchopulmonary affections and 100 and 100 per cent of the strains isolated from patients with urological diseases were resistant to gentamicin and carbenicillin, respectively. As for ampicillin, the respective figures were 74.2, 66.6, 66.6 and 100 per cent. All the strains of P. vulgaris isolated from patients with otitis, urological diseases and bronchopulmonary affections were resistant to ampicillin. The MIC of carbenicillin for all the strains except 4 indole-positive strains of P. vulgaris isolated from the faeces and bronchial excreta was much higher than the borderline values.     

Erratum to: Two novel species Enterococcus lemanii sp. nov. and Enterococcus eurekensis sp. nov., isolated from a swine-manure storage pit

A polyphasic taxonomic study using morphological, biochemical, chemotaxonomic and molecular genetic methods was performed on six strains of an unknown Gram-positive, nonspore-forming, facultative anaerobic coccus-shaped bacterium isolated from a swine-manure storage pit. On the basis of 16S rRNA, RNA polymerase-subunit (rpoA), and the 60-kilodalton chaperonin (cpn60) gene sequence analyses, it was shown that all the isolates were enterococci but formed two separate lines of descent. Pairwise 16S rRNA sequence comparisons demonstrated that the two novel organisms were most closely related to each other (97.9 %) and to Enterococcus aquimarinus (97.8 %). Both organisms contained major amounts of C_16:0, C_16:1 ω7c, and C_18:1 ω7c/12t/9t as the major cellular fatty acids. Based on biochemical, chemotaxonomic, and phylogenetic evidence, the names Enterococcus lemanii sp. nov. (type strain PC32^T = CCUG 61260^T = NRRL B-59661^T) and Enterococcus eurekensis sp. nov. (type strain PC4B^T = CCUG 61259^T = NRRL B-59662^T) are proposed for the hitherto undescribed species.     

Characteristics of E.coli O157 strains isolated in Poland from clinical material and food samples

E. coli belonging to the O157 serological group are among the organisms isolated most frequently out of all the so called entero-hemorrhagic E. coli strains (EHEC). Since several years they have been isolated also in Poland. The purpose of the present study was determination on selected phenotypic and genotypic properties of E. coli O157 strains isolated in our country from clinical material samples and from food. The serotype of the strains was determined, together with the following properties regarded as pathogenicity markers of verotoxic E. coli strains such as absence of beta-glucuronidase activity and sorbitol fermentation ability, as well as production of verotoxins SLT I and/or SLT II and entero-hemolysin. Besides that, by the PCR method the fragments of the genes coding for verotoxins, intimin and enterohaemolysin were amplified. The products of PCR were analysed by the restriction enzyme analysis (RFLP). All verotoxic E. coli O157 strains isolated in Poland were analysed by the pulsed field gel electrophoresis of genomic DNA (PFGE). The studied group comprised E. coli O157 strains, among them 40 strains were isolated from human faeces and 5 from food. The remaining strains were the reference E. coli O157:H7 EDL 933 and G 5244 strains and strains from NIH collection. The obtained results showed that the tested strains were a very varying population. 21 of them (all isolated from food, 11 from faeces and 5 reference strains) belonged to serotype O157:H7, five were not peritrichous O157:NM and the remaining ones had other ciliary antigen than H7. All strains isolated from food, reference strains and only 3 O157:NM strains isolated from humans were verotoxic. The strains from food and two reference strains produced only SLT II, 2 of 3 strains isolated from humans and one reference strain also produced only SLT II and the other produced both verotoxins. Apart from these 13 verotoxic strains all remaining strains caused sorbitol fermentation.