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PubMed1994

Conjugative transfer of tetracycline resistance in rumen streptococcal strains.

In 11% of tested Streptococcus bovis strains a conjugative transfer of tetracycline resistance was observed when mating experiments were carried out on membrane filters. The recipient strain used was S. bovis BM114 with chromosomal resistance to rifampicin. In addition, in two strains tetracycline resistance was transferred also to recipient strain Enterococcus faecium AL6. The transfer frequencies were in the range of 10(-6) to 10(-3). The donor strains were screened for the presence of plasmids and one up to four bands of plasmid DNA in all tested strains were revealed. In spite of that isolation of plasmid DNA was successful only in 53/4/114 transconjugants. Transconjugant 32/114 contained amylase activity which was higher than in the donor strain.

Animals↗
PubMed2005

High-level aminoglycoside resistant enterococci isolated from swine.

Approximately 42% (187/444) of swine enterococci collected between the years 1999 and 2000 exhibited high-level resistance to gentamicin (MIC > or =500 microg/ml), kanamycin (MIC > or =500 microg/ml), or streptomycin (MIC > or =1000 microg/ml). Eight aminoglycoside resistance genes were detected using PCR, most frequently ant(6)-Ia and aac(6')-Ii from Enterococcus faecium. Twenty-four per cent (45/187) of total high-level aminoglycoside-resistant isolates and 26% (4/15) of isolates resistant to high levels of all three antimicrobials were negative for all genes tested. These data suggest that enterococci isolated from swine contain diverse and possibly unidentified aminoglycoside resistance genes.

Aminoglycosides↗
PubMed2005

Molecular epidemiology of high-level aminoglycoside-resistant enterococci isolated from patients in a university hospital in southern Italy.

OBJECTIVES: We evaluated the genetic and molecular basis of high-level resistance to gentamicin and amikacin in 91 clinical isolates of Enterococcus faecalis and Enterococcus faecium in a university hospital in southern Italy from 1987 to 2003. METHODS: Antibiotic susceptibility was evaluated by disc diffusion and microdilution methods. Genotyping was performed by PFGE and dendrogram analysis. Aminoglycoside resistance genes were analysed by multiplex PCR. Aminoglycoside resistance gene transfer was performed by filter mating. RESULTS: In our strain collection, 44% of E. faecalis and 52% of E. faecium were high-level-resistant to gentamicin. Fifty-two PFGE profiles were identified for E. faecalis and 15 for E. faecium. Although the majority of PFGE patterns were single isolates, four patterns (two for E. faecalis and two for E. faecium) were isolated each in 8 and 4, and 6 and 4 different patients, respectively. The aac(6')-Ie-aph(2'')-Ia gene was responsible for high-level resistance to gentamicin and amikacin in E. faecalis and E. faecium; the aph(2'')-Id gene responsible for resistance to gentamicin was also isolated in E. faecium; the aph(3')-IIIa and ant(4')-Ia genes responsible for resistance to amikacin were also isolated in E. faecalis and E. faecium. High-level resistance to gentamicin, along with the aac(6')-Ie-aph(2'')-Ia gene, was transferred at a frequency of about 10(-5) to 10(-8) per recipient cell in 14 of 17 E. faecalis and 3 of 4 E. faecium different genotypes. CONCLUSIONS: The spread of the aac(6')-Ie-aph(2'')-Ia gene was responsible for high-level resistance to gentamicin and amikacin among enterococci isolated from patients in our geographical area.

Acetyltransferases↗
PubMed2004

Overexpression and characterization of an aminoglycoside 6'-N-acetyltransferase with broad specificity from an epsilon-poly-L-lysine producer, Streptomyces albulus IFO14147.

Streptomyces albulus IFO14147 produces epsilon-poly-L-lysine, which exhibits antimicrobial activity. In the MIC studies with antibiotics, S. albulus IFO14147 was shown to be resistant to kanamycin and amikacin, which are aminoglycoside (AG) antibiotics. We report here the isolation of the AG-resistance gene from S. albulus IFO14147 and the substrate specificity of the gene product, AAC(6')-Isa, which catalyzes N-acetylation at the 6' position of AGs, thereby inactivating them. Kinetic studies revealed that this enzyme has remarkably wide substrate specificity. The V(max)/K(m) values determined for AGs vary by a factor of up to 6,300, a much wider range than those observed for the AAC(6')s from Enterococcus faecium [AAC(6')-Ii] and Salmonella enteritidis [AAC(6')-Iy]. In addition, AAC(6')-Isa was able to acetylate lividomycin A, which has a hydroxy group at the 6' position. Enzymatically acetylated lividomycin A was found to be highly susceptible to mild base hydrolysis, suggesting that the enzyme also catalyzes O-acetyltransfer.

Acetyltransferases↗
PubMed1996

A highly vancomycin-resistant laboratory mutant of Staphylococcus aureus.

A resistant mutant with vancomycin MIC of 100 micrograms/ml was isolated relatively easily through step pressure in the laboratory from a Staphylococcus aureus strain with initial MIC of 1.5 micrograms/ml for the antibiotic. Upon addition of vancomycin (50 micrograms/ml) to the growth medium mass increase of the culture and peptidoglycan synthesis continued but cell division (daughter cell separation), cell wall turnover and autolysis were inhibited, resulting in the production of multicellular clumps of bacteria. Parallel with the increase of culture density, the concentration of vancomycin measured both by biological activity and by HPLC gradually declined in the culture medium. Cell division and wall turnover of the culture resumed with the production of cells of normal morphology at the time when the concentration of the drug in the medium decreased below 0.5-1.0 micrograms/ml. There was no detectable change in the antibiotic concentration in the culture medium during growth of a vancomycin-resistant (vanA-positive) strain of Enterococcus faecium and an intrinsically vancomycin-resistant strain of Leuconostoc. The vancomycin-resistant staphylococcal mutant gave no signal with the vanA or vanB DNA probes and contained no detectable D-lactate terminating cell wall precursors. The biochemical mechanism and clinical significance of such glycopeptide-resistant mutants remained to be established.

Anti-Bacterial Agents↗
PubMed1998

Antibacterial activity of lonchocarpol A.

Lonchocarpol A, a flavanone, demonstrates in vitro inhibitory activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. This activity is antagonized by mouse plasma, which may account for its lack of in vivo activity. This compound demonstrates no differentiation with respect to the inhibition of RNA, DNA, cell wall, and protein synthesis.

Animals↗
PubMed2003

Quinupristin-dalfopristin and linezolid: evidence and opinion.

Quinupristin-dalfopristin and linezolid demonstrate in vitro activity against a wide range of gram-positive bacteria, including many isolates resistant to earlier antimicrobials. Quinupristin-dalfopristin is inactive against Enterococcus faecalis but has been effective for treatment of infections due to vancomycin-resistant Enterococcus faecium associated with bacteremia. In comparative trials, linezolid proved to be equivalent to comparator agents, resulting in its approval for several clinical indications. The almost-complete bioavailability of linezolid permits oral administration. Each agent can cause adverse effects that may limit use in individual patients. Resistance to these drugs has been encountered infrequently among vancomycin-resistant E. faecium. Resistance to quinupristin-dalfopristin is rare among staphylococci in the United States, and resistance to linezolid is very rare. Whether there is any benefit to use of these agents in combination regimens, and whether there are circumstances in which they might be alternatives to cell-wall active antibiotics for treatment of bone or endovascular infections, are questions that deserve further study.

Acetamides↗
PubMed2000

Identification and antimicrobial susceptibility of enterococci isolated from the root canal.

Enterococci are occurring in opportunistic infections involving the oral cavity. This study has identified enterococcal species in 29 endodontic infections undergoing treatment with Ca (OH)2 dressings. The in vitro antimicrobial susceptibility of 29 isolated enterococcal strains was determined. Enterococcus faecalis was speciated for 26 isolates and Enterococcus faecium for three isolates. In vitro antimicrobial susceptibility testing revealed enterococcal isolates resistant to benzylpenicillin, ampicillin, clindamycin, metronidazole and tetracycline but sensitive to erythromycin and vancomycin. Due to low sensitivity to antimicrobial agents, enterococci may be selected in root canals undergoing standard endodontic treatment and significantly contribute to endodontic treatment failures.

Ampicillin↗
PubMed1996

Comparison of antimicrobial properties of monoterpenes and their carbonylated products.

Some monoterpenes and their carbonylated products were evaluated for their antibacterial and antifungal properties. The carbonylation of tested monoterpenes was shown to increase the bacteriostatic and fungistatic activities specifically by the contact method. Concerning the killing effects, only (1R,2S,5R)-isopulegol, its carbonylated products, and (R)-carvone showed significant bactericidal activities, particularly against Enterococcus faecium and Escherichia coli above a concentration of 10 microliters/ml. A fungicidal efficiency of (1R,2S,5R)-isopulegol and (R)-carvone against Aspergillus niger was also noted. It seems that the presence of an oxygenated function in the framework increases the antimicrobial properties. However, monoterpenes were more active using a micro-atmosphere method.

Anti-Bacterial Agents↗
PubMed2000

[Preliminary results of antibiotic resistance monitoring in the Netherlands].

Qualitative tests are used to monitor antimicrobial resistance in bacteria of animal origin in the Netherlands. Quantitative information on trends in resistance is thus not obtained. Moreover, in general a limited panel of antibiotics is tested. The present study describes resistance in zoonotic food-borne pathogens Salmonella, Campylobacter, and Escherichia coli O157 isolated from human clinical cases and from faeces of healthy food animals in 1998 and 1999, as determined with quantitative susceptibility tests. The resistance of the indicator organisms E. coli and Enterococcus faecium isolated from faecal samples of broilers and pigs randomly sampled at slaughterhouses was also determined. For this end, faecal samples from veal calves were sampled in 1996 and 1997 at the three main Dutch veal calf slaughterhouses. In 1998 only a limited number of faecal samples of veal calves were taken at farms. For E. coli and Salmonella the following antibiotics were tested: amoxicillin, amoxicillin-clavulanic acid, piperacillin, cefotaxime, ceftazidime, imipenem, gentamicin, doxycycline, trimethoprim, trimethoprim/sulphamethoxazole, ciprofloxacin, chloramphenicol, florfenicol, carbadox, and flumequine. For E. faecium the following antibiotics were tested: amoxicillin, amoxicillin-clavulanic acid, chloramphenicol, doxycycline, erythromycin, vancomycin, teicoplanin, streptomycin ('high level' > 2000 mg/ml), gentamicin ('high level' > 500 mg/ml), ciprofloxacin, bacitracin, flavofosfolipol, salinomycin, quinupristin-dalfopristin, virginiamycin, tilmicosin, avilamycin, and everninomycin. For Campylobacter the following antibiotics were tested: erythromycin, doxycycline, gentamicin, carbadox, flavofosfolipol, ciprofloxacin, trimethoprim/sulphamethoxazole, amoxicillin, and metronidazole.

Animals↗
PubMed2002

[Enterococcal meningitis revealing endocarditis].

INTRODUCTION: Enterococci are frequently responsible for endocarditis, but a rare cause of meningitis. OBSERVATION: A 55 years-old man presented with Enterococcus faecium meningitis. Systematic transoesophageal echocardiography (TOE), despite the absence of organic murmur and the negativity of the hemocultures, revealed a concomitant aortic endocarditis. CONCLUSION: Review of the literature suggests that the association of endocarditis with enterococcal meningitis is far from accidental. We suggest that a TOS be conducted systematically when faced with this disease. The therapeutic implications are important, notably regarding the duration of antibiotherapy.

Diagnosis, Differential↗
PubMed1996

Vancomycin-resistant enterococci. The 'superbug' scourge that's coming your way.

Strains of vancomycin-resistant enterococci (VRE) have emerged and spread widely throughout the United States during the last few years. Multiply-resistant strains of Enterococcus faecium are especially troublesome because they are often resistant to all commercially available antimicrobial agents. At present, VRE infections occur most often in hospitalized patients with severe underlying disease who have undergone invasive procedures and received prolonged courses of broad-spectrum antimicrobial therapy. Because therapeutic options are limited, prevention of spread from patients with known cases to other vulnerable patients is essential.

Anti-Bacterial Agents↗
PubMed2005

Rectal colonization and frequency of enterococcal cross-transmission among prolonged-stay patients in two Swedish intensive care units.

The aims of this study were to gain insight into the dynamics of the rectal flora during prolonged ICU stay, with a particular focus on colonization and cross-transmission with resistant pathogens, and to evaluate methods for the rapid isolation of relevant bacteria from rectal swabs. Patients admitted to a general intensive care unit (GICU) or a cardiothoracic ICU (TICU) at the University Hospital of Linköping, Sweden, between 1 November 2001 and January 2002 with a length of stay > 5 d were included (n = 20). Chromogenic UTI agar medium was used for discrimination of different species, and appropriate antibiotics were added to detect resistance. Direct plating was compared to enrichment broth for a subset of specimens. The study showed an early alteration in rectal flora, with a dramatic decrease in Gram-negative rods in favour of Gram-positive bacteria. An ampicillin- and high-level gentamicin resistant clone of Enterococcus faecium was found in 6 of 10 patients in the GICU and 2 of 11 patients in the TICU. Enrichment broth did not enhance the detection of Gram-negative bacteria compared to direct plating on Chromogenic UTI medium, but enrichment broths were needed for optimal detection of resistant Gram-positive bacteria.

Aged↗
PubMed2002

[Neonatal meningitis due to Enterococcus spp.: presentation of four cases].

AIM: Enterococci are unusual etiologic agents of bacterial meningitis and account for only 0.3-4% of all cases. Neonatal enterococcal meningitis, which is rarely reported in the medical literature, presents characteristics that are significantly different from enterococcal meningitis affecting other age groups, particularly adults. PATIENTS AND METHODS: We retrospectively reviewed the clinical records of four newborns diagnosed with enterococcal meningitis in our center. Two were premature and two were term infants. Three were affected with early-onset meningococcal sepsis and one with late-onset sepsis. Risk factors for infection included intrapartum maternal fever in one case and prematurity in two cases, with prolonged stay in the neonatal intensive care unit and application of invasive procedures, and prior antibiotic treatment in one of infant. There were no apparent risk factors in the fourth case. Enterococcus faecalis was the causal agent in three cases and Enterococcus faecium in one. None of the enterococci were vancomycin-resistant. Antibiotic treatment included ampicillin and combinations of ampicillin and cefotaxime, ampicillin and amikacin, and vancomycin and gentamicin. None of the patients died. CONCLUSIONS: Enterococci rarely cause bacterial meningitis, though newborns seem more susceptible to this infection. With adequate bactericidal therapy, clinical outcome appears to be generally favorable.

Adult↗
PubMed2001

Efficacy of nisin in combination with protective cultures against Listeria monocytogenes Scott A in tofu.

Nisin can be used as a biopreservative to control growth of Listeria monocytogenes in various minimally processed foods. Tofu is an example of a non-fermented soybean product, which may allow growth of Listeria at refrigeration temperatures and in which nisin may be applied to prevent multiplication of Listeria. The efficacy of nisin against Listeria may be compromised by the emergence of spontaneous nisin-resistant mutants. Exposure of L. monocytogenes Scott A to nisin in a culture medium or in a food product results in an initial reduction of Listeria population which is followed by regrowth of survivors to nisin during further incubation. In vitro studies using Standard I Nutrient broth showed that Enterococcus faecium BFE 900-6a and Lactobacillus sakei Lb 706-1a used as protective cultures in combination with nisin were able to suppress proliferation of Listeria cells not killed by nisin at 10 degrees C. Growth and bacteriocin production of these two strains and a third protective culture, Lactococcus lactis BFE 902 was also observed in soymilk and tofu at 10 degrees C. Inoculation studies with tofu prepared with nisin and protective cultures showed that lower amounts of nisin are required for an effective inhibition of L. monocytogenes Scott A when either E. faecium BFE 900-6a or Lc. lactis BFE 902 are used in addition. The combination of nisin with these bacteriocinogenic lactic acid bacteria (LAB) resulted in a complete suppression of listerial growth in homemade tofu stored at 10 degrees C for 1 week. Lb. sakei Lb 706-1a was less effective and did not prevent a slight increase of L. monocytogenes Scott A numbers during storage.

Anti-Bacterial Agents↗
PubMed1997

Microbiologic evaluation of needleless and needle-access devices.

OBJECTIVE: This study was carried out to determine whether needleless intravenous access devices are more likely to allow microorganisms to enter the fluid pathway than intravenous needle-access devices. METHODS: A laboratory study was conducted with two needleless and one intravenous needle-access devices and Enterococcus faecium as a bacterial challenge. Inocula of E. faecium were prepared on the basis of the numerical estimates of 1000 to 10,000 colony-forming units (CFU)/cm2 of bacterial flora on dry regions of skin (arms, legs, and hands). The septum of each access device was inoculated with 10 to 20 microliters of a 10(4) to 10(5) CFU/ml challenge suspension, which was allowed to dry on the surface of the septum. In the first part of the experiment, the needleless or needle-access cannula of each device was used to puncture the corresponding septum without previously disinfecting the top of the septum. In the second part, the contaminated septum was punctured after disinfecting the septum with a 70% isopropyl alcohol wipe. After each puncture, trypticase soy broth was flushed through the fluid pathway of the intravenous access device, collected, and cultured by the membrane filtration technique. The septum of each injection-site cap and the needleless or needle-access cannula were sampled with sterile premoistened swabs. Swabs were cultured on blood agar plates. RESULTS: The rate of fluid pathway contamination was 100% (40/40) for one of the needleless intravenous access devices and 80% (20/25) for the other when septa were contaminated with E. faecium and not disinfected before puncture. The rate for the intravenous needle-access device was 72% (18/25). When the septa of the three different devices tested were disinfected with 70% isopropyl alcohol, E. faecium was isolated on only one septum from all devices tested in part two (1/74, 1.3%). CONCLUSIONS: These laboratory studies demonstrate that there is no statistically significant difference in the rate of fluid pathway contamination between needleless and intravenous needle-access devices. However, if the septa of either needleless or needle systems are not disinfected before puncture, a high rate of fluid pathway contamination may occur.

Catheters, Indwelling↗
PubMedDate not supplied

[Splenic abscess secondary to massive bee bite in immunocompetent host. A case report].

INTRODUCTION: Spleen abscesses are considered as an infrequent infectious disease. An increase in its presentation has been seen due to certain pathologies or clinical conditions associated with immune suppression, endocarditis being one of the most frequent causes. Gram-positive aerobes are the main causal agents with non-specific clinical manifestations. CT scan and ultrasound are the elective choices for diagnosis and imaging support for punction and drainage. OBJECTIVE: To describe the case of a patients with splenic abscess and its possible association with massive bee bite. CASE REPORT: A 51-year-old man, with no important medical history, suffered a massive bee bite and developed anaphylactic shock. He was managed at the emergency room where 116 bee stings were removed from the patient. He was discharged after 3 days. Eight days later he complained of abdominal pain localized in the left upper quadrant, persisting for 3 weeks. Abdominal pain increased and was accompanied by malaise, vomiting, fever, signs of peritonitis and leucocytosis. CT scan showed left pleural effusion, a single hypodense lesion in the inferior pole of the spleen, and thickness of the parenchyma. The patient was diagnosed with spleen abscess drained to cavity and was submitted to surgery. Surgical findings included localized peritonitis, friable spleen, and 200 ml of pus. Splenectomy was performed and IV antibiotic therapy was started. Blood culture, viral profile, Widal reactions, and serological test for HIV were negative. Secretion (pus) culture was positive for Enterococcus faecium. CONCLUSIONS: Spleen abscess is a rare entity and unusual diagnosis, representing a high mortality in non-treated patients. According to our search, there is no literature-based evidence of a similar case with this association. This report represents the first case of the association between spleen abscess and massive bee bite.

Abscess↗