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R Vanhoof

Publications and source records attributed to R Vanhoof.

At least 19 recordsLinked to original sources
PubMed1999

Aminoglycoside resistance in Gram-negative blood isolates from various hospitals in Belgium and the Grand Duchy of Luxembourg. Aminoglycoside Resistance Study Group.

A total of 1102 consecutive clinical blood isolates, including 897 Enterobacteriaceae and 205 non-fermenting bacilli, were obtained from 13 university and university-affiliated hospitals, which were divided into a Northern and a Southern group. Resistance to gentamicin, tobramycin, netilmicin, amikacin and isepamicin was determined using a microdilution technique according to NCCLS procedures. The overall mean resistance level was 5.9% for gentamicin, 7.7% for tobramycin, 7.5% for netilmicin, 2.8% for amikacin and 1.2% for isepamicin. Resistance to amikacin and isepamicin was significantly higher in the Northern hospitals than in the Southern hospitals. In total, 157 isolates were found not to be susceptible to aminoglycosides. By PCR, 179 aminoglycoside resistance mechanisms, i.e. 150 genes encoding modifying enzymes and 29 permeability mechanisms, were detected in 148 isolates. A resistance mechanism could not be detected in nine isolates. Moreover, in a further 14 isolates the resistance profile was not fully explained by the detected genes. The aac(6')-I genes were found to be the most predominant resistance mechanism in both the Northern and Southern isolates, followed by aac(3) genes and permeability resistance. A total of 29 non-susceptible isolates harboured a combination of genes, 72.4% of which were a combination with the aac(6')-lb gene. The majority of these combinations were broad-spectrum combinations which represented 9.0% of the resistance mechanisms in non-susceptible Enterobacteriaceae and 19.3% in the non-fermenting bacilli.

Aminoglycosides↗
PubMed1998

Surveillance of pneumococcal resistance in Belgium during winter 1996-1997.

This study tested 212 pneumococcal isolates from 9 institutions for their susceptibilities to penicillin, ampicillin, amoxycillin, amoxycillin/clavulanate, cefaclor, cefuroxime, cefotaxime, imipenem, tetracycline, erythromycin, and clarithromycin using NCCLS-standardized microdilution. Penicillin-insusceptibility was 12.3% [5.7% intermediate (0.12-1 microgram/ml) and 6.6% high-level (> or = 2 micrograms/ml)], tetracycline-insusceptibility (> or = 4 micrograms/ml) 31.1%, and erythromycin-insusceptibility (> or = 0.5 microgram/ml) 31.1% as well. Erythromycin-insusceptible isolates showed cross-insusceptibility to clarithromycin. Penicillin-susceptible isolates were susceptible to all beta-lactams. MICs of all beta-lactams rose with those of penicillin for penicillin-insusceptible isolates. Ampicillin and penicillin were equally potent against penicillin-insusceptible isolates, imipenem, cefotaxime, and amoxycillin +/- clavulanate were more potent (generally 5, 1, and 1 doubling dilution, respectively), and cefuroxime and cefaclor less potent (generally 1 and 6 doubling dilutions, respectively). Most penicillin-insusceptible isolates were high-level resistant to cefaclor (> or = 32 micrograms/ml). Although MICs of all beta-lactams rose with those of penicillin, resistance to penicillin was not absolute in terms of cross-resistance. Most penicillin-intermediate and high-level penicillin-resistant isolates remained fully susceptible and intermediate, respectively, to amoxycillin +/- clavulanate, cefotaxime, and imipenem, but not to cefuroxime. Penicillin-susceptible isolates were 76.9%, 42.3%, and 34.6% co-insusceptible to tetracycline, erythromycin, and tetracycline plus erythromycin, respectively. Most penicillin-, tetracycline-, and erythromycin-insusceptible isolates were of capsular types 23 >> 6 > 19 > 32, 19 > 6 > 28 > 23, and 19 > 6 > 14 > 23, respectively. Compared to winter 1994-1995, insusceptibility to penicillin, tetracycline, and erythromycin rose by some 4%, 4%, and 13%, respectively.

Adolescent↗
PubMed1997

Characterization of the 6'-N-aminoglycoside acetyltransferase gene aac(6')-Im [corrected] associated with a sulI-type integron.

The amikacin resistance gene aac(6')-Im [corrected] from Citrobacter freundii Cf155 encoding an aminoglycoside 6'-N-acetyltransferase was characterized. The gene was identified as a coding sequence of 521 bp located down-stream from the 5' conserved segment of an integron. The sequence of this aac(6')-Im [corrected] gene corresponded to a protein of 173 amino acids which possessed 64.2% identity in a 165-amino-acid overlap with the aac(6')-Ia gene product (F.C. Tenover, D. Filpula, K.L. Phillips, and J. J. Plorde, J. Bacteriol. 170:471-473, 1988). By using PCR, the aac(6')-Im [corrected] gene could be detected in 8 of 86 gram-negative clinical isolates from two Belgian hospitals, including isolates of Citrobacter, Klebsiella spp., and Escherichia coli. PCR mapping of the aac(6')-Im [corrected] gene environment in these isolates indicated that the gene was located within a sulI-type integron; the insert region is 1,700 bases long and includes two genes cassettes, the second being ant (3")-Ib.

Acetyltransferases↗
PubMed1996

Changes in major populations of methicillin-resistant Staphylococcus aureus in Belgium.

A total of 102 epidemic methicillin-resistant Staphylococcus aureus (MRSA) isolates collected in 13 Belgian hospitals during two periods (1981-1985 and 1991-1992) were tested for phage-type, for the presence of aminoglycoside-modifying enzymes (AME), and examined by arbitrarily primed polymerase chain reaction (AP-PCR). All isolates, but five, belonged to a few distinct phage-types of group III. Most isolates expressed a combination of AAC(6')-APH(2") with APH(3')III, and ANT(4',4") or both. Both phage-typing and AME suggested a change in the MRSA population between the two periods but the AP-PCR method revealed only slight differences.

Aminoglycosides↗
PubMed1996

Rabies prophylaxis.

In humans, rabies still is a fatally evolving encephalomyelitis caused by a Rhabdovirus of the genus Lyssavirus. In general, the disease is contracted through a contact with an infected mammal. Taxonomically, different rabies and closely related rabies-like viruses can be distinguished. New molecular identification techniques can be utilized as epidemiological tools to study the geographic distribution and presence in different reservoirs of the viruses. Antigenic diversity and new insights in the mechanisms of the immune response can have serious implication in vaccine strategies. Virus detection for diagnostic and epidemiological purposes can be done by immunofluorescency, by inoculating murine neuroblastoma cells and by using molecular techniques. Rabies is a zoonosis with a worldwide distribution. In Belgium, the epizootic is present in the Southern part of the country. Fox vaccination campaigns contributed significantly to the eradication of the virus from its natural reservoir. The importance of the prophylactic and therapeutic use of the vaccine, the control of wildlife animal reservoir and stringent public health measures to combat rabies is discussed. Due to stringent control measures, no endogenous case of human rabies have been reported since 1922 in Belgium.

Animals↗
PubMed1996

In vitro susceptibilities of 176 clinical isolates of Streptococcus pneumoniae to 11 beta-lactams, erythromycin, and tetracycline.

One hundred seventy six consecutive, non-duplicate pneumococcal isolates from clinical specimens collected from November 1994 through February 1995 in nine general hospitals throughout Belgium were tested for their in vitro susceptibilities to penicillin, ampicillin, amoxycillin with and without clavulanate, cefaclor, cefuroxime, cefonicid, cefprozil, cefpodoxime, cefotaxime, imipenem, tetracycline, and erythromycin by means of the NCCLS microdilution test. The overall rate of decreased susceptibility to penicillin was 12.5%, including 6.3% of intermediately and 6.3% of fully resistant isolates. Penicillin, ampicillin amoxycillin, amoxycillin/clavulanate, cefuroxime, cefotaxime and imipenem had the highest activity on a weight basis (MIC50 < or = 0.008 microgram/ml), followed by cefpodoxime and erythromycin (MIC50 of 0.015 microgram/ml), cefprozil and tetracycline (MIC50 of 0.12 microgram/ml), and eventually, cefaclor and cefonicid (MIC50 of 0.5 microgram/ml). Aggregate rates of susceptible plus intermediately resistant isolates at NCCLS-recommended breakpoints, i.e. overall percentages of isolates likely to respond to increased antibiotic doses in vivo (except for meningitis), were 100.0% for imipenem and cefotaxime, 98.9% for amoxycillin with and without clavulanate, 93.8% for penicillin, and 90.9% for cefuroxime. Overall rates of susceptibility to erythromycin and tetracycline amounted to 78.4% and 72.7%, respectively. MIC values of all beta-lactams increased with those of penicillin. Ampicillin was equally active as penicillin against isolates with reduced susceptibility to the latter (MIC90 of 2 micrograms/ml); imipenem, cefotaxime, and amoxycillin with and without clavulanate however, were more active (MIC90 3, 1, and 1 doubling dilution, respectively, below that of penicillin), while cefpodoxime, cefuroxime, cefprozil, cefonicid, and cefaclor on the other hand, were less active (MIC90, 1, 1, 2, 5, and 5 doubling dilutions, respectively, above that of penicillin). In conclusion, the present data confirm that pneumococcal resistance to penicillin has increased in Belgium, suggest that resistance to erythromycin may have stabilised, and reveal an unexpectedly high rate of resistance to tetracycline. Imipenem was the most active antibiotic tested overall, and amoxycillin with or without clavulanate the most active oral antibiotic, with activity almost similar to that of cefotaxime.

Anti-Bacterial Agents↗
PubMed1995

The role of lipopolysaccharide anionic binding sites in aminoglycoside uptake in Stenotrophomonas (Xanthomonas) maltophilia.

Aminoglycoside resistance was investigated in six clinical isolates of Stenotrophomonas (Xanthomonas) maltophilia by studying the uptake kinetics and by using a radiochemical method to detect aminoglycoside modifying enzymes. Furthermore, the lipopolysaccharides (LPS) were extracted and characterized by SDS-PAGE and chemical analysis. Dansyl-polymyxin displacement experiments confirmed the availability of anionic binding sites. Growing cells of the isolates bound dansyl-polymyxin but were not lysed.

Aminoglycosides↗
PubMed1994

Detection by polymerase chain reaction of genes encoding aminoglycoside-modifying enzymes in methicillin-resistant Staphylococcus aureus isolates of epidemic phage types. Belgian Study Group of Hospital Infections (GDEPIH/GOSPIZ).

The polymerase chain reaction (PCR) was used to identify the aacA-aphD, aphA3 and aadC genes, encoding the aminoglycoside-modifying enzymes AAC(6')-APH(2"), APH(3')III and ANT(4'4"), respectively, and the methicillin resistance determinant mecA, in epidemic aminoglycoside and methicillin-resistant isolates of Staphylococcus aureus. In total, 37 isolates collected in the period 1980-1985 and 81 isolates from the period 1991-1992 were obtained from 10 different Belgian hospitals. Epidemic isolates from the earlier period were characterised by phage type C (6/47/54/75) of phage group III, whereas two other epidemic phage types of group III-types A (77) and B (47/54/75/77/84/85)--were commonest in isolates from the second period. The bifunctional AAC(6')-APH(2") was the enzyme encountered most frequently. The prevalence of APH(3')III decreased significantly in the 1991-1992 period, while ANT(4',4") was found solely in isolates from this period. Resistance mechanisms were more complex in isolates from the 1991-1992 period and the mecA gene was detected in all isolates. The PCR results corresponded well with those obtained in the radiochemical phosphocellulose paper binding assay. Isolates from the 1991-1992 period were shown to express significantly higher levels of acetyltransferase activity than isolates from the 1980s.

Acetylation↗
PubMed1993

Serotypes and extended spectrum beta-lactam resistance in aminoglycoside resistant Pseudomonas aeruginosa isolates from two Belgian general hospitals: a seven year study.

A total of 1896 isolates of Pseudomonas aeruginosa resistant to aminoglycosides and isolated during the period 1983-1989 in two Belgian general hospitals were included in this study. The most frequently encountered O serotypes were O4, O11, O12 and non-typable isolates. The majority of the isolates showed resistance to extended spectrum beta-lactam antibiotics (cefotaxime, ceftriaxone and cefepime). However, a low degree of resistance was found for ceftazidime. By contrast, amikacin and isepamicin, remained active on a significant number of aminoglycoside resistant isolates. In both hospitals, impermeability and AAC(3)II enzyme production were the most prevalent aminoglycoside resistance mechanisms. There were marked differences between the two hospitals with regard to the distribution of the O-serotypes and resistance profiles.

Amikacin↗
PubMed1993

Use of the polymerase chain reaction (PCR) for the detection of aacA genes encoding aminoglycoside-6'-N-acetyltransferases in reference strains and gram-negative clinical isolates from two Belgium hospitals.

Genes encoding aminoglycoside 6'-N-acetyltransferases, were identified using the polymerase chain reaction (PCR). Four sets of primers delineating DNA fragments of 209 bp, 250 bp, 260 bp and 347 bp, specific for the four known aacA genes, and probes within these fragments, were constructed based on the nucleotide sequences of the aacA genes. The specificity of the primers was evaluated using reference strains encoding various aminoglycoside-modifying enzymes. The primers reacted with their corresponding aacA genes and did not cross-react with genes coding for other aminoglycoside-modifying enzymes. One hundred and sixty-one aminoglycoside resistant clinical isolates showing AAC(6')I activity were tested using the PCR assays. The gene described by Tran Van Nhieu & Collatz (1987) was the most frequently identified aacA gene. One strain of Citrobacter freundii contained two distinct aacA genes. However, in 46% of the strains, the majority being Serratia spp. and Acinetobacter spp. none of the specific amplified DNA fragments for any of the known aacA genes could be detected.

Acetyltransferases↗
PubMed1992

Identification of the aadB gene coding for the aminoglycoside-2"-O-nucleotidyltransferase, ANT(2"), by means of the polymerase chain reaction.

The polymerase chain reaction (PCR) was used to identify the gene encoding the aminoglycoside-2"-O-nucleotidyltransferase, ANT(2"). Two primers, delineating a DNA fragment of 188 bp, and a specific probe within this fragment were constructed, based on the nucleotide sequence of the aadB gene encoding this enzyme. Reference strains producing different aminoglycoside-modifying enzymes were used to evaluate the specificity and the sensitivity of the test. Strains producing the ANT(2") enzyme showed the expected 188 bp DNA fragment after amplification. The oligonucleotide primers did not interact with genes encoding other aminoglycoside-modifying enzymes. Evaluation of a one-step single colony technique demonstrated that it was an acceptable alternative to the classic PCR test. The PCR method was used successfully to detect the presence of the aadB gene in 17 gentamicin-resistant clinical isolates.

Bacillus↗
PubMed1992

Comparative in vitro activity of cefepime and four extended-spectrum beta-lactams on 1,251 aminoglycoside-resistant gram-negative hospital strains.

Cefepime was the most active compound on the Enterobacteriaceae with a MIC90 of 0.26 microgram/ml and a resistance rate of 0.1%. Ceftazidime was the most active drug on the non-fermenting bacilli (MIC90 9.65 micrograms/ml; resistance rate 3%). Amikacin- and gentamicin-resistant strains showed a decreased susceptibility to the beta-lactams, though the Enterobacteriaceae and the non-fermenters remained fairly sensitive to cefepime and ceftazidime, respectively. Aminoglycoside-3-N-acetyltransferase was the most prevalent enzyme and was often associated with intermediate resistance or resistance to beta-lactams. Non-fermenters showing aminoglycoside impermeability were very often intermediately resistant or resistant to beta-lactams.

Aminoglycosides↗
PubMed1992

A 56-month prospective surveillance study on the epidemiology of aminoglycoside resistance in a Belgian general hospital.

In this survey, we studied the effect of extensive amikacin usage on the epidemiology of aminoglycoside resistance in a general hospital. The baseline resistance in the 12 months before amikacin was 5.8% for amikacin, 15.2% for gentamicin, 16.4% for tobramycin and 14.0% for netilmicin. During the following 44 months, amikacin was the aminoglycoside of first choice. In the first 2 years of this phase, resistance to amikacin did not change significantly. Later, amikacin resistance rose significantly, mainly due to the introduction of amikacin-resistant Enterobacter aerogenes strains. In general there was a significant decrease in resistance to gentamicin and tobramycin. Resistance mechanisms were examined in 380 strains. AAC(3)V, and AAC(6')I alone or coupled with ANT(2") or AAC(3) were the most prevalent enzymes. In the amikacin phase, we noticed a significant increase of strains harbouring the AAC(6')I enzyme, while strains with the AAC(3)V were less frequently isolated. Strains with permeability resistance did not become more prevalent during the period of extensive amikacin use.

Amikacin↗
PubMed1991

Characterization of Staphylococcus aureus and Salmonella spp. strains isolated from bovine meat in Zaïre.

A large majority (87.4%) of 190 Staphylococcus aureus isolates from fresh beef in Lubumbashi (Zaïre) belonged to the human St. aureus ecovar; 81.2% of the phage-typed human strains were partially or solely lysed by phages of group III. Thirteen of the 52 tested strains (25.0%) were enterotoxin producers; nine of these (69.2%) were positive for staphylococcal enterotoxin A. Sixteen serotypes were identified among the 122 Salmonella isolates and nearly all these strains were susceptible to the 8 different antibiotics tested.

Animals↗
PubMed1990

Activity of cefotiam in combination with beta-lactam antibiotics on enterobacterial hospital strains.

By using checkerboard titrations the effect of cefotiam combined with different beta-lactam antibiotics on fifty strains of Enterobacteriaceae moderately susceptible (minimal inhibiting concentration greater than or equal to 8 mg/l) or resistant (minimal inhibiting concentration greater than or equal to 64 mg/l) to cefotiam was evaluated. The following compounds were tested: cefamandole, cefazolin, cefmenoxime, cefotaxime, cefotiam, ceftazidime, cefuroxime, mecillinam and piperacillin. The synergistic effect varied markedly. The combination cefotiam-mecillinam showed the highest rate of synergistic activity. Antagonism was found in 1% of the combinations.

Anti-Bacterial Agents↗