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Biomedical subjects

A Bauernfeind

Publications and source records attributed to A Bauernfeind.

At least 37 records · Page 2Linked to original sources
PubMed1998

Plasmid-encoded AmpC beta-lactamases: how far have we gone 10 years after the discovery?

The dogma that ampC genes are located exclusively on the chromosome was dominant until about 10 years ago. Since 1989 over 15 different plasmid-encoded AmpC beta-lactamases have been reported from several countries. Most of these enzymes evolved in two clusters. The major cluster includes several enzymes with a high similarity to CMY-2, which is the closest related chromosomal AmpC enzyme of Citrobacter freundii. A second cluster centers around CMY-1. It is less homogeneous and not closely related chromosomal AmpC enzymes. Molecular diversification by amino acid substitutions does not usually translate into a change in the resistance phenotype. At this time, CMY-2 appears to be the most prevalent and widely distributed. Further global increase of prevalence and diversity of plasmidic AmpC beta-lactamases have to be anticipated in the next millenium.

Bacterial Proteins↗
PubMed1998

[Frequency and antibiotic susceptibility of oxacillin resistant Staphylococcus aureus in a teaching hospital].

From October 1993 till October 1994, 115 oxacillin resistant Staphylococus aureus strains were isolated in the laboratory of a teaching hospital. This was 2.4% of all of the Staphylococcus aureus strains. The bacteria were isolated from 30 patients, 7 medical personnel and in the environment of the infected patients. Most of the isolates were cultured from blood cultures, wound swabs and drains. If the referring hospitals has been informed about the MRSA status of the patients, several transmissions could have been prevented. In 10 infected patients, the MRSA strains were isolated from the nose, throat and hands. The isolates were also found on the hands of several personnel and in the patients environment, suggesting that the strains had been widely spread. The MRSA strains predominated in the medical and surgical intensive care units and in 2 general surgical wards. They were only found sporadically in other departments (Ophthalmology, Gynaecology, Paediatrics and Urology). MRSA-strains were more resistant to imipenem, ofloxacin, gentamicin, trimethoprim-sulfamethoxazole, tetracycline, erythromycin and clindamycin as oxacillin-sensitive Straphylococcus aureus strains. Genotyping (Restriction-Fragment-Length-Polymorphism) revealed six different strain patterns. The same RFLP types were mainly found on different wards. We conclude that various clones of MRSA may have emerged independently within one hospital and that their spread between wards was remarkably limited. Subsequent intensive hygiene measures have been successful in reducing the number of new isolates.

Anti-Bacterial Agents↗
PubMed1997

Decrease in nosocomial pneumonia in ventilated patients by selective oropharyngeal decontamination (SOD).

OBJECTIVE: To determine the influence of selective oropharyngeal decontamination (SOD) on the rate of colonization and infection of the respiratory tract in intensive care patients requiring mechanical ventilation for more than 4 days. A financial assessment was also performed. DESIGN: Randomized, prospective, controlled study using amphotericin B, colistin sulfate (polymyxin E), and tobramycin applied to the oropharynx and systemic cefotaxime prophylaxis. SETTING: Anesthesiology intensive care unit (ICU) of a 1500-bed hospital. PATIENTS: A total of 88 patients admitted as emergencies and intubated within less than 24 h were enrolled. Fifty-eight patients received SOD and 30 patients served as controls. Randomization was in the proportion of 2 : 1 study patients to controls. INTERVENTIONS: Microbiological samples from the oropharynx and other infected sites were taken at the time of admission, then twice a week and after extubation. MEASUREMENTS AND RESULTS: With the use of SOD, colonization was significantly reduced. Furthermore, the infection rate decreased from 77% in the controls to 22% in the study patients. Staphylococcus aureus was the main potential pathogen causing colonization and pneumonia. Number of days in the ICU, duration of ventilation, and mortality were not significantly decreased. The total cost of antibiotics was reduced. Development of resistance was not observed. CONCLUSIONS: The use of SOD significantly reduced the colonization and pneumonia and the total charge for antibiotics. The length of stay in the ICU, duration of ventilation, and mortality were similar. No resistance was observed. Staphylococcus aureus was selected by SOD in some patients and the clinical relevance needs further observation.

Adult↗
PubMed1997

Comparison of the antibacterial activities of the quinolones Bay 12-8039, gatifloxacin (AM 1155), trovafloxacin, clinafloxacin, levofloxacin and ciprofloxacin.

The in-vitro activities of the quinolones Bay 12-8039, gatifloxacin (AM 1155), trovafloxacin, clinafloxacin, levofloxacin and ciprofloxacin were compared. Gram-positive cocci were most susceptible to Bay 12-8039, clinafloxacin and trovafloxacin; Enterobacteriaceae and fastidious organisms were most susceptible to clinafloxacin [corrected]; Pseudomonas spp. were most susceptible to clinafloxacin and ciprofloxacin; anaerobes, Helicobacter pylori and Campylobacter jejuni were most susceptible to gatifloxacin, clinafloxacin and trovafloxacin. Against gram-positive cocci, the only agents that were more active than ciprofloxacin were those carrying an azabicyclo (trovafloxacin, Bay 12-8039), 3-amino-pyrrolidinyl (clinafloxacin) or 3-methyl-piperazinyl (gatifloxacin) moiety at position C7.

Anti-Infective Agents↗
PubMed1997

A novel class C beta-lactamase (FOX-2) in Escherichia coli conferring resistance to cephamycins.

An Escherichia coli strain resistant to a broad spectrum of beta-lactams, including cephamycins, was isolated from a patient suffering from urinary tract infection. A resistance plasmid (pMVP-7) was transferred from the clinical isolate to an Escherichia coli recipient. Both strains produce a cefoxitin-hydrolyzing beta-lactamase focusing at pI 6.7. The phenotype was similar to that of a Klebsiella pneumoniae strain producing cephamycinase FOX-1, so primers were selected from the FOX-1 sequence to amplify the bla gene of the transconjugant. The PCR product obtained was sequenced. The percentage of identity of the deduced amino acid sequence with sequences of other AmpC-type beta-lactamases was 96.9% with FOX-1, 74.9% with CMY-1, and 67.7% with MOX-1. This new plasmid-mediated enzyme is most closely related to FOX-1 (11 amino acid exchanges). We therefore propose the designation FOX-2.

Adult↗
PubMed1996

A multinational European survey on the in-vitro activity of rufloxacin and other comparative antibiotics on respiratory and urinary bacterial pathogens.

The antibacterial activity of rufloxacin was confirmed against a large number of respiratory and urinary tract pathogens collected in five European countries. In terms of both MIC90 values and percentages of susceptible isolates found, this new quinolone showed useful in-vitro activity against Mycoplasma catarrhalis, Haemophilus influenzae and Klebsiella pneumoniae, with a large proportion of Staphylococcus aureus also covered, while, as expected Streptococcus pneumoniae and Streptococcus pyogenes were not included in its antibacterial spectrum. Rufloxacin was comparable with the other antibiotics against these pathogens with the exception of streptococci. Against these microorganisms, beta-lactams were the most active agents. Against the urinary pathogens the in-vitro activity of rufloxacin is similar to that of norfloxacin although this latter drug is more active in terms of MIC90 values and in percentages of strains inhibited. In many cases more isolates were susceptible to the remaining comparator agents than to rufloxacin. However, there were no significant differences between the numbers of microorganisms inhibited by the various drugs and rufloxacin. The findings of this survey do not seem to modify the general picture which emerged in previous studies and further confirms its useful spectrum in different geographic settings.

Anti-Bacterial Agents↗
PubMed1996

Antibiotic susceptibility patterns of respiratory isolates of Klebsiella pneumoniae in Europe and the USA in 1992 and 1993. The Alexander Project Collaborative Group.

The overall antibiotic susceptibility of Klebsiella pneumoniae isolates collected in 1992 (n = 35) and 1993 (n = 85) was highly variable ranging from 0.8% for amoxycillin to 95.8% for ceftriaxone. On a weight for weight basis, the activity of the compounds decreased in the following sequence: ceftriaxone, cefixime, co-trimoxazole, ciprofloxacin, ofloxacin, cefaclor, amoxycillin/clavulanate, doxycycline, cefuroxime, chloramphenicol, amoxycillin. A small percentage of resistant strains was found for each of the compounds (between 0.8% for ceftriaxone and 12.5% for chloramphenicol) with the exception of amoxycillin which was almost uniformly resistant. There was a trend for the percentage of resistant strains to increase between the two study years for all compounds except for chloramphenicol. Resistance to beta-lactams in France and the USA is likely to have been due to strains producing extended spectrum beta-lactamases.

4-Quinolones↗
PubMed1996

Characterization of the plasmidic beta-lactamase CMY-2, which is responsible for cephamycin resistance.

The phenotype of Klebsiella pneumoniae HEL-1 indicates a plasmidic cephamycinase gene (blaCMY-2). Its sequence shows one open reading frame coding for a protein of 381 amino acids. CMY-2 is classified as class C beta-lactamase that is closely related to the plasmidic enzymes BIL-1 and LAT-1 and the chromosomal AmpC of Citrobacter freundii. The blaCMY-2 gene possibly was translocated onto a plasmid of C. freundii which spread to K. pneumoniae.

Amino Acid Sequence↗
PubMed1996

Sequences of beta-lactamase genes encoding CTX-M-1 (MEN-1) and CTX-M-2 and relationship of their amino acid sequences with those of other beta-lactamases.

Amino acid sequences determined either by protein sequencing or by DNA sequencing are identical for cefotaximases CTX-M-1 and MEN-1, whereas CTX-M-2 is 84% identical to CTX-M-1/MEN-1. Both beta-lactamases are distantly related to other plasmidic class A enzymes (homology to TEM-1 is 38.1% for CTX-M-1/MEN-1 and 36.5% for CTX-M-2); the closest relationship was with the chromosomal beta-lactamase of Klebsiella oxytoca E23004 (homologies of 74.5% for CTX-M-1/MEN-1 and 77.9% for CTX-M-2). The cefotaximases CTX-M-1/MEN-1 and CTX-M-2 represent two members of a new subgroup of plasmidic class A beta-lactamases.

Amino Acid Sequence↗
PubMed1996

Characterization of beta-lactamase gene blaPER-2, which encodes an extended-spectrum class A beta-lactamase.

Plasmidic extended-spectrum beta-lactamases of Ambler class A are mostly inactive against ceftibuten. Salmonella typhimurium JMC isolated in Argentina harbors a bla gene located on a plasmid (pMVP-5) which confers transferable resistance to oxyiminocephalosporins, aztreonam, and ceftibuten. The beta-lactamase PER-2 (formerly ceftibutenase-1; CTI-1) is highly susceptible to inhibition by clavulanate and is located at a pI of 5.4 after isoelectric focusing. The blaPER-2 gene was cloned and sequenced. The nucleotide sequence of a 2.2-kb insert in vector pBluescript includes an open reading frame of 927 bp. Comparison of the deduced amino acid sequence of PER-2 with those of other beta-lactamases indicates that PER-2 is not closely related to TEM or SHV enzymes (25 to 26% homology). PER-2 is most closely related to PER-1 (86.4% homology), an Ambler class A enzyme first detected in Pseudomonas aeruginosa. An enzyme with an amino acid sequence identical to that of PER-1, meanwhile, was found in various members of the family Enterobacteriaceae isolated from patients in Turkey. Our data indicate that PER-2 and PER-1 represent a new group of Ambler class A extended-spectrum beta-lactamases. PER-2 so far has been detected only in pathogens (S. typhimurium, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis) isolated from patients in South America, while the incidence of PER-1-producing strains so far has been restricted to Turkey, where it occurs both in members of the family Enterobacteriaceae and in P. aeruginosa.

Amino Acid Sequence↗
PubMed1996

Comparative characterization of the cephamycinase blaCMY-1 gene and its relationship with other beta-lactamase genes.

A plasmidic beta-lactamase which hydrolyzed cephamycins was first detected and reported in 1989. At that time its description was restricted to phenotypic characteristics. We analyzed nucleotide sequence of its gene and explored it genetic relationship with other bla genes. The deduced amino acid sequence of the blaCMY-1 product was compared with those of other known plasmidic cephamycinases and of chromosomal AmpC beta-lactamases. The results indicate that the relationship of CMY-1 is closest to MOX-1 among the plasmidic cephamycinases and to AmpC of Pseudomonas aeruginosa among the chromosomal cephalosporinases. We conclude that the plasmidic cephamycinases described up to now may be classified into three families, as follows: CMY-1, MOX-1, and FOX-1 with AmpC of P. aeruginosa; CMY-2, BIL-1 and LAT-1 with AmpC of Citrobacter freundii; and MIR-1 with AmpC of Enterobacter cloacae. Plasmidic cephamycinases are now recognized as clinically relevant class C beta-lactamases.

Amino Acid Sequence↗
PubMed1996

Molecular epidemiology of Klebsiella pneumoniae producing SHV-5 beta- lactamase: parallel outbreaks due to multiple plasmid transfer.

Over a period of 22 months, 32 patients treated in three independent intensive care units of the Innsbruck University Hospital were infected with extended-spectrum beta-lactamase-producing members of the family Enterobacteriaceae (30 Klebsiella pneumoniae isolates, 1 Klebsiella oxytoca isolate, and 1 Escherichia coli isolate). As confirmed by sequencing of a bla gene PCR fragment, all isolates expressed the SHV-5-type beta-lactamase. Genomic fingerprinting of epidemic strains with XbaI and pulsed-field gel electrophoresis grouped 20 of 21 isolates from ward A into two consecutive clusters which included 1 of 3 ward B isolates. All six K. pneumoniae isolates from ward C formed a third cluster. Stool isolates of asymptomatic patients and environmental isolates belonged to these clusters as well. Additionally, 2,600 routine K. pneumoniae isolates from the surrounding provinces (population, 900,000) were screened for SHV-5 production. Only one of six nonepidemic isolates producing SHV-5 beta-lactamase was matched with the outbreak strains by genomic fingerprinting. Plasmid fingerprinting, however, revealed the epidemic spread of a predominant R-plasmid, with a size of approximately 80 kb, associated with 29 of the 30 K. pneumoniae isolates. This plasmid was also present in the single K. oxytoca and E. coli isolates from ward C and in three nonepidemic isolates producing SHV-5. Our results underline that strain typing exclusively on the genomic level can be misleading in the epidemiological investigation of plasmid-encoded extended-spectrum beta-lactamases. Our evidence for multiple events of R-plasmid transfer between species of the family Enterobacteriaceae in this nosocomial outbreak stresses the need for plasmid typing, especially because SHV-5 beta-lactamase seems to be regionally spread predominantly via plasmid transfer.

Base Sequence↗
PubMed1994

Clinical significance and spread of fluoroquinolone resistant uropathogens in hospitalised urological patients.

The minimum inhibitory concentrations (MIC) of ciprofloxacin were determined for 441 uropathogens from patients with complicated and/or hospital acquired urinary tract infections (UTI). None of the Enterobacteriaceae was resistant (MIC > or = 4 mg/l), but 21.7% of enterococci, 28.3% of Pseudomonas spp. and 38.5% of staphylococci were. Subtyping of the strains revealed that with staphylococci there was no clonal spread of resistant strains. In the case of enterococci and Pseudomonas spp., however, cross infections played a major role (46% and 40% respectively). In a retrospective analysis of 370 UTI episodes caused by Pseudomonas aeruginosa (74), enterococci (185) or staphylococci (111) there was no difference between sensitive and resistant strains with respect to clinical aspects and rates of elimination by appropriate anti-bacterial therapy. The rates of spontaneous disappearance without antibacterial therapy ranged from 28% in the case of P. aeruginosa up to 63% in the case of coagulase-negative staphylococci. This implies that especially in UTI caused by gram-positive cocci an indication for antibacterial therapy should be weighted thoroughly and fluoroquinolones should only be used in accordance with sensitivity testing.

Anti-Infective Agents↗
PubMed1994

[Nosocomial colonization and infection by multiresistant Enterobacter cloacae strains on a pediatric oncological unit].

A multiresistant E. cloacae strain spread during a six month period in a paediatric oncology ward amongst nine children, who had different tumors and malformations. Three children who had shared a room were especially affected. E. cloacae was isolated 122 times from the children with tumors and five times from their environment. Specimens from which the bacteria were isolated, included blood cultures, catheter tips, wound swabs, drains, skin and mucous membranes from most parts of the body. The majority of the E. cloacae strains were resistant to ampicillin, mezlocillin, piperacillin, azlocillin, doxycycline and cephalosporins of the second and third generation and sensitive to imipenem, aminoglycosides and quinolones. The antimicrobial resistance patterns of the E. cloacae strains from the paediatric oncology ward were compared to those isolated from other wards in the hospital. E. cloacae isolates from the intensive care unit had a reduced sensitivity to beta-lactam antibiotics, whereas the isolates from the other wards were, with the exception of ampicillin, sensitive to beta-lactam antibiotics. The analysis of the E. cloacae strains from the paediatric oncology ward revealed the same antimicrobial resistance pattern, bacteriocin type, RFLP-type and an identical enzyme and whole cell profile. Isolates from other wards showed considerably deviating patterns. The systematic registration and isolation of patients, colonized or infected with multiresistant E. cloacae strains, together with infection control methods, lead to a significant reduction in infections.

Child↗