Review of treatment options for lyme borreliosis.

Lyme borreliosis (Lyme disease) is the most common tick-borne bacterial infection and the incidence is increasing in parts of Europe and the USA. Prompt antimicrobial therapy using oral agents such as doxycycline or amoxicillin is successful among more than 90% of patients. Inadequate penetration of oral agents into the CNS may result in the development of overt neuroborreliosis. The parenteral agent ceftriaxone is the drug of choice for severe acute and chronic infections, due to good penetration into CSF, convenient single daily dosage regimen and proven high efficacy in clinical trials involving a wide variety of disseminated infections. Regardless of therapeutic agent, there appears to a small minority of patients (<10%) who do not respond; such cases may be due to long-term persistence of borrelial cysts and to misdiagnoses based solely on seropositivity. Several adjunct therapies are available, including hyperbaric oxygen therapy and immune system supplements, but clinical trials have yet to be conducted.

Assessing the quality of life for patients with chronic rhinosinusitis using the "Rhinosinusitis Disability Index".

Quality of life studies are increasingly being use as the primary outcome measure in chronic rhinosinusitis. The Rhinosinusitis Disability Index (RSDI) is a recently designed validated measure that has not been used in clinical studies. We have used the RSDI on 53 patients with chronic rhinosinusitis and compared the results to their endoscopic score and self-rated symptom score. Our data showed that the mean total quality of life score was 42 with a range of 5 to 69 (SD 17). The means of the functional, emotional and physical domains were 13 (range 0 to 27, SD 6), 13 (range 0 to 25, SD 7) and 16 (range of 2 to 32, SD of 7) respectively. There was no correlation between endoscopic score and either the patient's self-rated symptom score or RSDI score. The correlation between the self-rated symptom score and total quality of life score was significant (p = 0.02). Various areas of the patients' quality of life were shown to be affected by chronic rhinosinusitis.

Isolation from clinical sources of Burkholderia cepacia possessing characteristics of Burkholderia gladioli.

Further characterization of 32 clinical isolates originally identified as Burkholderia cepacia by biochemical and fatty acid profiling revealed the presence of 12 strains bearing partial resemblance to the closely related species Burkholderia gladioli. These strains were highly resistant to a wide range of antibiotics including ticarcillin (with or without clavulanic acid), cefsulodin, imipenem, the aminoglycosides, colistin and fosfomycin. They typically produced a red-brown pigment and possessed distinct, although quite diverse biochemical profiles. This reinforces the previous opinion that hybrids between B. cepacia and B. gladioli exist and may possess a significant pathogenic role. It also suggests that further taxonomic clarification is required in the genus Burkholderia.

Rapid detection of antimicrobial activity using flow cytometry.

Different antibiotic classes vary considerably in their modes of action and hence in their effects on the bacterial cell. Flow cytometry was used to analyse E. coli cells treated with five antibiotics differing in their modes of action. The ratio of protein content, as measured by fluorescence, to forward light scatter (i.e., FL1:FSC) provided a simple and reliable way of detecting within 2 h of treatment antimicrobial activity at a 0.5 minimum inhibitory concentration. This ability to detect antimicrobial activity rapidly offers considerable advantages in drug research for the rapid detection of novel antimicrobials and may, with further development, find a use in the clinic for rapid susceptibility testing as an aid to the selection of therapy.

Evaluation of mupirocin E-test for determination of isolate susceptibility: comparison with standard agar dilution techniques.

Mupirocin E-test strips have been evaluated for their ease of use and accuracy in determining the susceptibilities of 171 strains of Staphylococcus spp., Streptococcus spp., Haemophilus influenzae, and Moraxella catarrhalis. The susceptibility of each strain was determined on two occasions, using parallel E-test and agar dilution methodologies each time. To ensure similar precisions for statistical analyses, E-test MICs were rounded up to a standard twofold agar dilution scale. Clear, elliptical zones were obtained against Staphylococcus spp. M. catarrhalis also gave clear zones, but the scale intercept was often difficult to interpret because of the irregular shape of the inhibition zone. Poor growth sometimes resulted in less-distinct zones of inhibition against Streptococcus spp. and H. influenzae. Excellent correlation was observed between the the E-test and agar dilution against Staphylococcus spp. and H. influenzae, with > 95% of the E-test values falling within one log2 dilution of the corresponding agar MIC. The correlation was lower for Streptococcus spp. and M. catarrhalis, with 86 and 83%, respectively, of E-test results falling within one log2 dilution of the agar MIC. When E-test MICs did not agree exactly with the corresponding agar MIC against Staphylococcus spp. or Streptococcus spp., there was a tendency for the E-test to give a lower MIC. This bias has little effect upon individual MICs in staphylococci or in the generation of susceptibility interpretation errors ( < 1.5% overall), but it could reduce population geometric mean MICs by factors of 0.78 to 0.83. This effect was more marked for Streptococcus spp., reducing the population mean by a factor of 0.73 and resulting in 0.7% major and 8% very major errors. In contrast, the E-test tended to give higher MICs against M. catarrhalis, resulting in 7.3% major errors and increasing the population geometric mean MIC by a factor of 1.60.

Structure-activity relationships within a series of C(7)-substitutedoxyiminocephalosporins containing the C(3)-methylaminopyridiniumthiomethyl substituent. Synthesis and biological properties of BRL 57342 and some close analogues.

(6R,7R)-7-[2-(2-Amino-4-thiazolyl)-2-[(Z)-[(S)-carboxy(3,4- dihydroxyphenyl)methyl]oxyimino]acetamido]-3-(1-methylaminopyri dinium-4-thiomethyl)ceph-3-em-4-carboxylate sodium salt (BRL 57342, 1f) combines excellent in vitro antibacterial potency against Gram-positive and Gram-negative bacteria, including P. aeruginosa and Acinetobacter spp., with excellent stability to extended spectrum beta-lactamases. This potency is reflected in in vivo efficacy studies.

Multi-resistance isolates possessing characteristics of both Burkholderia (Pseudomonas) cepacia and Burkholderia gladioli from patients with cystic fibrosis.

Multi-resistant strains from three UK centres, previously identified as Burkholderia (formerly Pseudomonas) cepacia, and associated with morbidity, mortality and transmission among patients with cystic fibrosis have been further characterised. Biochemical tests and fatty acid analyses indicate these strains to possess some characteristics atypical of B. cepacia but bearing close resemblance to Burkholderia gladioli, an organism previously regarded solely as a plant pathogen and a hindrance to the identification of B. cepacia. In contrast to the majority of reference strains, all multi-resistant clinical isolates possessed rough lipopolysaccharide which may be a major factor responsible for their increased antibiotic resistance and virulence. In view of the potential clinical and social problems in CF patients posed by these multi-resistant strains, it would seem prudent to consider the isolation of either B. cepacia or B. gladioli as of equal significance.

Cephaloridine resistance in gram-negative bacteria isolated in Scotland.

The incidence of cephaloridine resistance (minimum inhibitory concentration, MIC greater than 8 mg L-1) in isolates from urinary tract infections was 45.1% in Glasgow, 22.6% in Dundee and 25.9% in Edinburgh. The incidence of ampicillin resistance (MIC greater than 8 mg L-1) was even higher:- being 45.2% in Dundee and 48.5% in Edinburgh. In Glasgow, the incidence was 71.9% which is the highest proportion of ampicillin resistance reported in the United Kingdom. The cephaloridine resistant strains were examined for beta-lactamase production. Amongst these strains 50.8% produced only a chromosomal beta-lactamase, whereas 47.9% produced beta-lactamases which were potentially plasmid-mediated on the basis of biochemical tests. Only 1% of the resistant strains produced no detectable beta-lactamase.

The differential expression of genes for the PSE-4 beta-lactamase in Pseudomonas aeruginosa and the Enterobacteriaceae.

The PSE-4 beta-lactamase has been identified, for the first time, in two non-pseudomonal strains. The gene in Klebsiella pneumoniae 241 (dal1) was located on a plasmid (pUK700) and was freely transferable to other enterobacterial strains and Pseudomonas aeruginosa. On the other hand, the gene in Enterobacter cloacae A113 (dal2) could only be transferred in the presence of a mobilizing plasmid. When both these genes were transferred within the Enterobacteriaceae, the beta-lactamase produced was slightly different from the prototype 'Dalgleish' PSE-4 enzyme. However, when dal1 and dal2 were transferred to P. aeruginosa the enzyme expressed was identical to this prototype enzyme. In addition, both these genes expressed higher levels of PSE-4 beta-lactamase production in P. aeruginosa than found in the Enterobacteriaceae. Thus it appears that the biochemical properties of the PSE-4 gene products from dal1 and dal2 are host-modified.

Ampicillin resistance in Haemophilus influenzae: identification of resistance mechanisms.

The incidence and mechanisms of ampicillin resistance (MIC greater than 1 mg/l) were investigated in 105 clinical isolates of Haemophilus influenzae collected in Edinburgh during 1983/4. Fifteen (14.3%) ampicillin-resistant strains were identified and these were non-serotypable and comprised six biotypes. Isoelectric focusing and beta-lactamase-inhibition studies demonstrated that production of the TEM-1 beta-lactamase was the principal mechanism of resistance in nine (60%) strains. Radiolabelling revealed that one beta-lactamase-positive strain also had an unusual penicillin-binding protein (PBP) profit. No beta-lactamase activity was detected in the other six (40%) ampicillin-resistant strains. Two beta-lactamase-negative ampicillin-resistant strains had atypical PBP profiles. SDS-PAGE analysis showed that four beta-lactamase-negative ampicillin-resistant strains, including one with altered PBPs, exhibited outer membrane protein profiles which differed from those of sensitive strains of the same biotype. The ampicillin-resistance mechanism of the remaining strain could not be determined. Thus, several resistance mechanisms, either acting individually or in combination, are implicated in ampicillin resistance in H. influenzae.

Selection of enhanced cefotaxime resistance in Enterobacter spp.

Four strains of Enterobacter spp. with different chromosomal beta-lactamase expression (inducible, constitutive or negligible) were grown in broth containing either cefoxitin or cefotaxime, then plated on to agar containing 20 mg cefotaxime per litre to quantitate the cefotaxime-resistant mutants present in the population. Spontaneous resistant mutants were initially isolated from each strain at frequencies of 10(-4) to 10(-5). These high frequencies of spontaneous mutation suggested that more than one type of mutational event could yield cefotaxime resistance. Induction of a high level of beta-lactamase in broth cultures was not in itself sufficient to confer a high level of cefotaxime resistance on the population, and increased resistance following selection of resistant mutants did not necessarily correlate with any significant increase in beta-lactamase activity.

Qualitative and quantitative aspects of beta-lactamase production as mechanisms of beta-lactam resistance in a survey of clinical isolates from faecal samples.

A study has been conducted to identify the beta-lactamases most likely to contribute to beta-lactam resistance in clinical populations and to investigate their interactions with cefuroxime and newer cephalosporins. A total of 217 ampicillin-resistant, Gram-negative isolates from faecal samples of healthy volunteers in Germany, South America and Amman were investigated. Such strains represent the 'gene pool' from which infections might arise. Escherichia coli was the prevalent species (59.9%) followed by Klebsiella spp. (20.3%) and Enterobacter cloacae (12.0%). At least 56.7% and possibly as high as 64.5% of strains owed their principal beta-lactamase activity to enzymes mediated by R-plasmids. The most prevalent R-plasmid mediated beta-lactamase was TEM-1 which was produced by 109 strains. The beta-lactamase activity of strains producing only a chromosomal enzyme was often markedly higher than that of strains also producing an R-plasmid mediated enzyme. The qualitative and quantitative aspects of beta-lactamase production were investigated in cell free and whole cell tests and this confirmed the superior broad spectrum beta-lactamase resistance of ceftazidime over other new cephalosporins.

The origin and properties of beta-lactamase satellite bands seen in isoelectric focusing.

Citrobacter diversus 2046E and Branhamella catarrhalis 2001E each produce a constitutive, chromosomally mediated broad-spectrum beta-lactamase. Isoelectric focusing of both enzymes revealed patterns of multiple 'satellite' bands. The principal satellite bands of each enzyme were isolated and characterized. Individual bands of each enzyme gave similar substrate profiles, molecular weights and responses to inhibitors to one another. The results support the theory that satellite bands are due to the loss and/or modification of specific amino acid residues resulting in biologically active molecules with altered nett charges.

Selection for increased penicillin titre following hybridization of divergent lines of Aspergillus nidulans.

Sexual hybridization of two divergent lines of Aspergillus nidulans, which had been selected for increased penicillin titre through successive cycles of mutagenesis, released considerable variation for this character. The recovery of segregants with titres equivalent to that of the unselected ancestor suggested that mutations in different genes had been selected in the two lines. However, complementary segregants with substantially improved titres were not found, indicating interactions, probably of a duplicate nature, among the induced mutations. All the genetic variation released by hybridization was fixed following two generations of selection for high titre, but only a small gain over the initial selection lines was achieved. Hybridization of divergent strains has been widely advocated as a means of strain development. The failure to achieve the anticipated gains in this programme is attributed primarily to the unfavourable interactions amongst the induced mutations. Whether similar interactions occur generally in crosses between strains selected by mutagenesis remains to be established and will be an important factor in determining the contribution of recombinational approaches to yield improvement.