Epidemiological investigation of fluoroquinolone resistance in infections due to extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae

The incidence of infections due to extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae (ESBL-EK) has increased markedly in recent years. Treatment is difficult because of frequent multidrug resistance. Although fluoroquinolones offer effective therapy for ESBL-EK infections, their usefulness is threatened by increasing fluoroquinolone resistance. To identify risk factors for fluoroquinolone resistance in ESBL-EK infections, a case-control study of all patients with ESBL-EK infections from 1 June 1997 through 30 September 1998 was conducted. Of 77 ESBL-EK infections, 43 (55.8%) were resistant to fluoroquinolones. Independent risk factors for fluoroquinolone resistance were fluoroquinolone use (odds ratio [OR], 11.20; 95% confidence interval [CI], 1.99-63.19), aminoglycoside use (OR, 5.83; 95% CI, 1.12-30.43), and long-term care facility residence (OR, 3.39; 95% CI, 1.06-10.83). The genotypes of fluoroquinolone-resistant ESBL-EK isolates were closely related. Efforts should be directed at modification of these risk factors to preserve the utility of fluoroquinolones in the treatment of ESBL-EK infections.

Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: risk factors for infection and impact of resistance on outcomes

The prevalence of antibiotic resistance among extended-spectrum beta-lactamase (ESBL)--producing Escherichia coli and Klebsiella pneumoniae has increased markedly in recent years. Thirty-three patients with infection due to ESBL-producing E. coli or K. pneumoniae (case patients) were compared with 66 matched controls. Total prior antibiotic use was the only independent risk factor for ESBL-producing E. coli or K. pneumoniae infection (odds ratio, 1.10; 95% confidence interval, 1.03--1.18; P=.006). Case patients were treated with an effective antibiotic a median of 72 hours after infection was suspected, compared with a median of 11.5 hours after infection was suspected for controls (P<.001). ESBL-producing E. coli or K. pneumoniae infection was associated with a significantly longer duration of hospital stay and greater hospital charges (P=.01 and P<.001, respectively). Finally, many ESBL-producing E. coli and K. pneumoniae isolates were closely related. ESBL-producing E. coli and K. pneumoniae infections have a significant impact on several important clinical outcomes, and efforts to control outbreaks of infection with ESBL-producing E. coli and K. pneumoniae should emphasize judicious use of all antibiotics as well as barrier precautions to reduce spread.

Performance of two rapid, single-use immunoassays for the detection of Clostridium difficile toxin A

Two rapid, single-use immunoassays for C. difficile toxin A, the Clearview C. DIFF A (Wampole Laboratories, Cranbury, N.J.) and the ImmunoCard Toxin A assays (Meridian Diagnostics Inc., Cincinnati, Ohio) were compared to the cytotoxin assay for their ability to detect C. difficile toxin in fecal specimens. A total of 537 specimens were tested and 47 (8.8%) were positive by the cytotoxin assay. The sensitivity, specificity, positive predictive value, and negative predictive value of the toxin A assays were as follows: 70.2% (95% CI, 57.1 to 83.3), 98.8% (95% CI, 97.8 to 99.8), 84.6% (95% CI, 73.3 to 95.9), and 97.2% (95% CI, 95.7 to 98.6) respectively for the Clearview assay; and 74.5% (95% CI, 62.0 to 86.9), 99.0% (95% CI, 98.1 to 99.9), 87.5% (95% CI, 77.3 to 97.8), and 97.6% (95% CI, 96.2 to 98.9) respectively for the ImmunoCard assay. Both toxin A assays are less sensitive than the cytotoxin assay, however, these assays offer a rapid and easy-to-perform test that may be used in conjunction with the cytotoxin assay for laboratory confirmation of C. difficile-associated disease.

Effects of storage and reperfusion oxygen content on substrate metabolism in the isolated rat lung

BACKGROUND

Lung transplantation requires a period of storage and ischemia; we examined the largely unknown effects of that period on intermediary metabolism.

METHODS

Two groups of isolated rat lung blocks (n = 16 each) were flushed with Euro-Collins solution and harvested. The lung blocks were immediately ventilated and either perfused for 30 minutes with an erythrocyte-based solution containing carbon 13 labeled substrates (group 1) or stored for 6 hours at 1 degree C and then reperfused (group 2). Half of each group was reperfused at a physiologic Po2 the other half at high Po2. Analysis of carbon 13 isotopomers was performed to determine substrate utilization through aerobic pathways in lung tissue.

RESULTS

Lungs from both groups oxidized all major substrates. The contribution of fatty acids to acetylcoenzyme acid oxidized in the citric acid cycle was significantly higher in group 2 than in group 1 (31.3% +/- 2.2% versus 22.0% +/- 2.1%, p < 0.05). Perfusate Po2 did not affect substrate preference. Gas exchange was worse in stored lungs.

CONCLUSIONS

After a period of hypothermic ischemia and storage, substrate preference in lung tissue exhibits a switch towards fatty acids. As fatty acid oxidation occurring after ischemia is deleterious in other organs, strategies to inhibit this process in stored lungs may warrant further investigation.

Evaluation of serum alkaline DNase activity in treatment monitoring of head and neck cancer patients

Our previously published data on breast cancer suggest that serum alkaline DNase, a known circulating tumour marker, can be used for treatment monitoring of cancer patients. Serum alkaline DNase activities were analyzed in 215 untreated head and neck cancer patients. The enzyme activity ranged from 0.17 to 97.97 IKU/l in untreated cancer patients. Responders (n = 314) showed significantly elevated activity of alkaline DNase as compared to untreated cancer patients (p < 0.001). While non-responders (n = 168) showed comparable activity with untreated cancer patients. Serum alkaline DNase activities were significantly elevated in responders as compared to non-responders (p < 0.001). Our clinical studies during follow-up of patients indicated that the variations in serum alkaline DNase activities in individual patients correlate closely with response to therapy. Serum alkaline DNase also appeared to be useful in predicting treatment response in the long-term follow-up of patients. Serum alkaline DNase was systematically examined as a possible indicator for recurrence in patients under complete remission. In conclusion, serum alkaline DNase may be useful as a treatment monitoring in patients with head and neck malignancies.

Sequence-based identification of Mycobacterium species using the MicroSeq 500 16S rDNA bacterial identification system

We evaluated the MicroSeq 500 16S rDNA Bacterial Sequencing Kit (PE Applied Biosystems), a 500-bp sequence-based identification system, for its ability to identify clinical Mycobacterium isolates. The organism identity was determined by comparing the 16S rDNA sequence to the MicroSeq database, which consists primarily of type strain sequences. A total of 113 isolates (18 different species), previously recovered and identified by routine methods from two clinical laboratories, were analyzed by the MicroSeq method. Isolates with discordant results were analyzed by hsp65 gene sequence analysis and in some cases repeat phenotypic identification, AccuProbe rRNA hybridization (Gen-Probe, Inc., San Diego, Calif.), or high-performance liquid chromatography of mycolic acids. For 93 (82%) isolates, the MicroSeq identity was concordant with the previously reported identity. For 18 (16%) isolates, the original identification was discordant with the MicroSeq identification. Of the 18 discrepant isolates, 7 (six unique sequences) were originally misidentified by phenotypic analysis or the AccuProbe assay but were correctly identified by the MicroSeq assay. Of the 18 discrepant isolates, 11 (seven unique sequences) were unusual species that were difficult to identify by phenotypic methods and, in all but one case, by molecular methods. The remaining two isolates (2%) failed definitive phenotypic identification, but the MicroSeq assay was able to definitively identify one of these isolates. The MicroSeq identification system is an accurate and rapid method for the identification of Mycobacterium spp.

Bacteremia caused by a novel isolate resembling leptotrichia species in a neutropenic patient

We report a case of Leptotrichia species bacteremia in a patient undergoing treatment for acute myelogenous leukemia. Like previously reported Leptotrichia species, this is a gram-variable, pleomorphic rod that is catalase negative and utilizes glucose and sucrose. However, it is more fastidious than previously reported isolates of Leptotrichia and may represent a novel species.

Probing the yeast phase-specific expression of the CBP1 gene in Histoplasma capsulatum

Histoplasma capsulatum is a pathogenic fungus that exists in two distinct forms. The saprophytic mycelial phase inhabits moist soil environments; once inhaled, hyphae and conidia convert to a unicellular yeast phase that is capable of parasitizing macrophage phagolysosomes. Yeasts cultures, but not mycelial cultures, release large quantities of a calcium-binding protein (CBP) which may be important in calcium acquisition during intracellular parasitism. In this study, we show that the gene encoding CBP (CBP1) is transcriptionally regulated. To identify promoter sequences that are important for yeast phase-specific activity, we created a series of fusions between successively truncated CBP1 5' untranslated regulatory sequences and the Escherichia coli lacZ gene. The fusions were constructed on a telomeric shuttle plasmid that can replicate autonomously in the fungus. By assaying for beta-galactosidase activity from H. capsulatum transformants, we identified a 102-bp region that mediates promoter activation and yeast phase promoter activity. Base pair substitution analysis suggests that the sequences between 839 and 877 bp upstream of the start codon are the most important for this positive regulation.

Synthesis and structure-activity relationships of a series of anxioselective pyrazolopyridine ester and amide anxiolytic agents

A series of 1-substituted 4-amino-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid esters and amides were synthesized and screened for anxiolytic activity in the shock-induced suppression of drinking (SSD) test. The compounds were also tested for their ability to displace [3H]flunitrazepam (FLU) from brain benzodiazepine (BZ) binding sites. Many compounds were active in these screens and, additionally, demonstrated a selectivity for the type 1 BZ (BZ1) receptor over the type 2 BZ (BZ2) receptor as indicated by Hill coefficients significantly less than unity and by analysis of [3H]FLU binding results from different brain regions. Based on the results of structure-activity studies of these compounds, a hypothesis was proposed to explain the structural features necessary for optimal interaction with brain BZ receptors. A detailed pharmacological evaluation of one of the most potent behaviorally active compounds (27) demonstrated it to be BZ1 selective; also, in comparison to diazepam, 27 showed minimal sedative and alcohol interactive properties at therapeutically effective doses.

Meropenem: evidence of lack of proconvulsive tendency in mice

The proconvulsive tendency of the novel carbapenem, meropenem was compared to that of imipenem, alone and in combination with cilastatin. The potentiation of metrazole-induced convulsions in mice was measured. Both imipenem and imipenem/cilastatin caused significant potentiation of metrazole-induced convulsions at a dose of 200 mg/kg, i.v. In contrast, meropenem (50-400 mg/kg, iv) failed to exhibit any significant potentiation of metrazole-induced seizures.

A simple and rapid method of inducing physical dependence with benzodiazepines in mice

Physical dependence was rapidly induced in mice by administering diazepam intraperitoneally twice daily using an incremental dosing regimen (50 to 450 mg/kg) for nine consecutive days. Withdrawal was induced (24 hr after the last dose) by administration of a benzodiazepine antagonist, RO-15-1788 (10 mg/kg, IP). All of the mice exhibited clear-cut withdrawal symptoms (i.e., convulsions) within minutes of antagonist treatment. This method offers a simple, reliable, high throughput procedure for the assessment of benzodiazepine-like physical dependence liability and withdrawal, and it would be useful for screening purposes.

Preclinical studies with pyrazolopyridine non-benzodiazepine anxiolytics: ICI 190,622

Tracazolate is a pyrazolopyridine anxiolytic that enhances the binding of [3H]-flunitrazepam [( 3H]FLU) to brain tissue. The discovery that a metabolite of tracazolate, desbutyltracazolate, was a weak inhibitor of [3H]FLU binding led to the synthesis of a series of potent anxiolytics. From this series, ICI 190,622 emerged as a viable drug candidate, being a potent anxiolytic in rats and monkeys. This anxiolytic agent appears to produce only minimal sedation. Furthermore, ICI 190,622 appears less likely to potentiate the actions of ethanol than diazepam. ICI 190,622 is also a potent anticonvulsant (anti-metrazol ED50 = 1.1 mg/kg, PO) in rodents. Neurochemically, ICI 190,622 is similar to the benzodiazepine anxiolytics. In vitro, ICI 190,622 competitively inhibited [3H]FLU binding in cerebral cortex with an IC50 of 81 nM and was 4.3-fold more potent in the cerebellum (IC50 = 19 nM). This suggests a selectivity for the Type 1 benzodiazepine binding site. In contrast, diazepam showed similar affinities in both regions (cerebral cortex = 7 nM and cerebellum = 9 nM). Following oral administration, ICI 190,622 displaced [3H]FLU binding from cerebellar membranes more potently than diazepam (ED50 = 3 and 6 mg/kg, respectively, 1 hour after administration). Thus, ICI 190,622 should be an effective anxiolytic with significant advantages over benzodiazepines.

Malignant fibrous histiocytoma of the second metacarpal

A case of low grade malignant fibrous histiocytoma (MFH) arising from a metacarpal bone in a 21 year old African female is presented. The rarity of this disorder is emphasized with review of the relevant literature.

Early congenital syphilis: clinico-radiologic features in 202 patients

Venereal syphilis is highly prevalent among women of child-bearing age in Zambia. It is estimated to contribute 25-30% of the perinatal mortality rate of 50 per 1,000 births at the University Teaching Hospital in Lusaka. Because of multisystem involvement, early congenital syphilis, the offshoot of maternal syphilis, has varied criteria for its diagnosis. Therefore, in an attempt to draw guidelines for an easier and more reliable diagnosis, the authors analyzed the clinico-radiologic features of congenital syphilis in 202 patients. Although all infants were under the age of six months, there were several significant differences in the manifestations of the disease among neonates and the postneonates. The younger infants had a higher incidence of jaundice and mortality, whereas joint swellings, skin rash, snuffles, anemia, and periosteal reaction visible in x-rays of long bones were typical findings among the older group. The radiologic changes were seen in greater than 95% of patients in both groups. About 84% of mothers had attended prenatal clinics, but less than 20% of the women had been tested for syphilis. Since early congenital syphilis is common in many parts of the world and since all serologic tests have limitations, awareness of appropriate diagnostic criteria is recommended for all medical personnel.

Pharmacology of pyrazolopyridines

Pyrazolopyridines (PZP's) in general represent a chemically unique class of non-sedative anxiolytic agents. Tracazolate (ICI 136,753) is a member of pyrazolopyridine series that has shown anxiolytic properties in animal models. Tracazolate demonstrates a wider separation between sedative and therapeutic doses than do benzodiazepines. In addition, tracazolate appears to cause fewer adverse interactions than the benzodiazepines in combination with barbiturates and alcohol. In interaction studies, tracazolate potentiated both the antimetrazol and anticonflict effects of chlordiazepoxide. Pyrazolopyridines cause enhancement of both 3H-flunitrazepam (3H-FLU) and 3H-GABA to their binding sites in brain. The enhancement of 3H-FLU binding by PZP's and GABA are additive and reversed by bicuculline. The enhancement of 3H-GABA binding by PZP's and benzodiazepines are additive and reversed by picrotoxin. It is hypothesized that the action of PZP's, and particularly tracazolate, may be related to their effects upon a GABA-stimulated chloride ionophore site. Finally, benzodiazepine antagonists (e.g., RO-15 1788) fail to reverse either the anxiolytic properties of 3H-FLU enhancers or their 3H-GABA binding enhancement effects. In contrast, benzodiazepine antagonists readily reverse the anxiolytic effects of benzodiazepines and non-benzodiazepines which cause 3H-FLU displacement. These data suggest that tracazolate, a non-benzodiazepine, has a pharmacological profile suggestive of novel anxiolytic activity.

Neurochemical characteristics of rats distinguished as benzodiazepine responders and non-responders in a new conflict test

Using a new rat conflict test it was found that 30% of the subjects failed to respond to benzodiazepines and other anxiolytic agents. This value is similar to that reported using more classical procedures such as the Geller-Seifter and Vogel conflict tests. Biochemical analysis of various brain regions from responder (R) and non-responder (NR) subjects revealed no significant differences in 5-HT1, 5-HT2, GABA receptor binding or GABA-activated benzodiazepine binding. However, a small, but significant, increase in basal benzodiazepine binding was noted in the hippocampus of NR rats. These findings suggest that the insensitivity of these animals to anxiolytics is probably unrelated to an alteration in serotonin, GABA or benzodiazepine binding sites in brain.

Novel non-benzodiazepine anxiolytics

Several new non-benzodiazepine anxiolytics are reported. These include tracazolate, zopiclone, CL218,872, CGS9896, buspirone, MK-801 and fenobam. A comparison of anticonflict effects and propensity to cause sedation and potentiate the actions of ethanol is given as well as their effects upon the binding of [3H]flunitrazepam in vitro. Their anxiolytic properties after treatment with the benzodiazepine antagonist, RO15-1788, are reported also. Tracazolate shows a wide separation between anxiolytic activity and ability to cause sedation and to potentiate alcohol. It enhanced binding of [3H]-flunitrazepam in contrast to benzodiazepines which displace it. Buspirone was without anticonflict activity and had no effect on benzodiazepine binding while fenobam and MK-801, also without effect on binding, showed large and small differences on causing sedation and potentiating alcohol respectively. Among the displacers of [3H]flunitrazepam zopiclone showed diminished sedation liability, compared to diazepam, as did CL218,872 and CGS9896. Zopiclone caused potentiation of ethanol however, at doses close to anxiolytic doses, while CL218,872 and CGS9896 showed a wider safety margin for potentiation of ethanol compared to anxiolytic doses. The drug RO15-1788 antagonised the anticonflict effects of benzodiazepine displacers and had no effects upon the other agents studied.

Differential antagonism of the anticonflict effects of typical and atypical anxiolytics

Selected benzodiazepine and non-benzodiazepine agents were studied alone or in the presence of benzodiazepine antagonists in the shock-induced suppression of drinking (SSD) procedure in rats. The disinhibitory activity of chlordiazepoxide, CL218,872, zopiclone and CGS 9896 was antagonized by two benzodiazepine antagonists, RO-15-1788 and CGS 8216. In contrast, the disinhibitory activity of fenobam, meprobamate, phenobarbital and tracazolate was not antagonized by either RO 15-1788 and CGS 8216. From these data it is apparent that the anticonflict activity of agents that bind to benzodiazepine receptors is blocked by benzodiazepine antagonists. In contrast, the activity of anxiolytics that are not displacers are unaffected even at higher doses.

A sensitive and selective monkey conflict test

A conflict model is described in which clinically effective antianxiety agents exhibit pronounced anticonflict activity. Male squirrel monkeys were trained to depress a bar for 5 sec to obtain food reinforcement. The 6 hr test session was comprised of an initial 3 hr period in which each 5 sec response was punished and then a 3 hr unpunished period. Trained monkeys would rarely be shocked and would make most of their responses during the non-punished period. Both benzodiazepine (chlordiazepoxide and diazepam) and non-benzodiazepine (meprobamate and phenobarbital) anxiolytics produced pronounced and unequivocal increases in punished responding. Other psychoactive agents (damphetamine, chlorpromazine, ethanol, morphine, amitriptyline and imipramine) did not produce an increase in punished responding. Sensitivity (i.e., large magnitude effects), selectivity, stable baseline performance and fully automated features make this test useful in identifying potential anxiolytic agents in primates.

Pharmacological properties of tracazolate: a new non-benzodiazepine anxiolytic agent

Tracazolate (ICI 136,753, 4-butylamino-1-ethyl-6-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester) demonstrated dose-related anticonflict activity in rats and mice. The potency of tracazolate appears to be one-quarter to one-half that of chlordiazepoxide. No tolerance to the anticonflict activity of either tracazolate or chlordiazepoxide was evident following 12 consecutive days of treatment. Tracazolate exhibits a much greater separation between sedative and therapeutic doses than does chlordiazepoxide. Furthermore, based on rodent studies, tracazolate should be much less likely than the benzodiazepines to potentiate the actions of barbiturates and ethanol in man. Tracazolate potentiated both the anticonvulsant and anxiolytic effects of chlordiazepoxide in rodents. Unlike benzodiazepines, tracazolate enhances the binding of benzodiazepines to its receptor site. These results suggest that tracazolate is a novel agent with potential clinical utility as an anxiolytic drug.

Effects of isoproterenol and chlordiazepoxide on drinking and conflict behaviors in rats

Isoproterenol, a beta-adrenergic agents, induced drinking in water-satiated rats. Isopropeternol exhibited significant anti-conflict activity on water-deprived rats in the Shock-induced Suppression of Drinking (SSD) procedure. Chlordiazepoxide (CDP), at the highest dose tested, also increased drinking in non-deprived naive rats. As expected, CDP demonstrated highly significant anti-conflict activity in thirsty rats (SSD test). These results suggest that in conflict procedures, where food or water is used as a reward, agents that affect the consumatory drive mechanisms could show up as "false positives." Moreover, agents that affect primary drives (e.g., CDP), in addition to their anti-anxiety activity, could show additive activity in such conflict procedures.

Benzodiazepine blockade of passive-avoidance task in mice: a state-dependent phenomenon

Four benzodiazepines (diazepam, chlordiazepoxide, halazepam, lorazepam) were tested for their effects on the acquisition of a passive-avoidance task in mice. This was done to determine whether amnesic effects, as reported in humans after diazepam and lorazepam, could be demonstrated by blockade of passive-avoidance responding in mice and, if so, to investigate the possible causes of the blockade by studying the relationships between the blockade and times of drug administration. Each of these benzodiazepines, at doses that did not alter overt behavior, blocked acquisition of the passive-avoidance response when they were administered to mice prior to the training session, but not when they were administered after the training session or prior to testing 24 h later. The block of avoidance responding was reversed, however, when the drugs were administered prior to both training and test sessions. These results suggest that state-dependent learning occurred; i.e., apparent amnesia occurred in the test session with untreated mice that had undergone passive-avoidance learning 24 h earlier under the influence of drug.