Hyperostotic bone disease in a wombat (Vombatus ursinus).

Little is known about wombat diseases in general, and about their congenital diseases in particular. In the current study, the skeleton of a common wombat (Vombatus ursinus) that exhibited generalized hyperostosis is analyzed, and possible diagnoses are reviewed. Macromorphological analyses revealed that the diaphyses of the long bones manifested an increased diameter with extensive diaphyseal new-bone formation (periosteal and endosteal). Cross-sections of the diaphyses showed that the cortical-medullary demarcation was indistinct. The calvarial bones were thickened. Radiographs showed uniform sclerosis of the long bones with loss of trabecular pattern. Microradiography showed extensive bone remodeling, a hyper-vascularized lamellated layer of bone and numerous linear formation defects. Possible causes for the lesions, including sclerosing bone dysplasia disorders, acquired syndromes causing hyperostosis, and metabolic diseases typical of animals in captivity, are discussed.

Degenerative lumbar spinal stenosis and lumbar spine configuration.

As life expectancy increases, degenerative lumbar spinal stenosis (DLSS) becomes a common health problem among the elderly. DLSS is usually caused by degenerative changes in bony and/or soft tissue elements. The poor correlation between radiological manifestations and the clinical picture emphasizes the fact that more studies are required to determine the natural course of this syndrome. Our aim was to reveal the association between lower lumbar spine configuration and DLSS. Two groups were studied: the first included 67 individuals with DLSS (mean age 66 ± 10) and the second 100 individuals (mean age 63.4 ± 13) without DLSS-related symptoms. Both groups underwent CT images (Philips Brilliance 64) and the following measurements were performed: a cross-section area of the dural sac, vertebral body dimensions (height, length and width), AP diameter of the bony spinal canal, lumbar lordosis and sacral slope angles. All measurements were taken at L3 to S1. Vertebral body lengths were significantly greater in the DLSS group at all levels compared to the control, whereas anterior vertebral body heights (L3, L4, L5) and middle vertebral heights (L3, L5) were significantly smaller in the LSS group. Lumbar lordosis, sacral slope and bony spinal canal were significantly smaller in the DLSS compared to the control. We conclude that the size and shape of vertebral bodies and canals significantly differed between the study groups. A tentative model is suggested to explain the association between these characteristics and the development of degenerative spinal stenosis.

Selection of Bacillus anthracis isolates resistant to antibiotics.

OBJECTIVE: Long-term therapy for anthrax might induce antimicrobial resistance in Bacillus anthracis. The aim of the present study was to investigate the potential of 18 different antibiotics to select resistant isolates of B. anthracis, (ST-1 and Sterne strains). METHODS: Resistant isolates were selected by serial passages on brain heart infusion agar containing increasing concentrations of antibiotics (from the MIC upwards). RESULTS: The MICs of ciprofloxacin, ofloxacin and levofloxacin increased from 0.125-0.25 to 8 mg/L, that of moxifloxacin increased from 0.03-0.06 to 8 mg/L, in both strains, and the MIC of garenoxacin increased from 0.015 to 0.5 mg/L for the ST-1 strain and from 0.03 to 8 mg/L for the Sterne strain. The MICs of tetracycline and minocycline increased from 0.125 to 2-8 mg/L and 0.06 to 1 mg/L, respectively. The MIC of vancomycin increased from 2.5 to 20 mg/L for the ST-1 strain and from 5 to 20 mg/L for the Sterne strain. Linezolid exhibited an MIC increase from 2 to 4 mg/L for both strains. The MIC of quinupristin/dalfopristin increased from 0.125 to 64-128 mg/L. Erythromycin demonstrated an MIC increase from 1 to 128 mg/L, that of clarithromycin increased from 0.125 to 8-64 mg/L and that of telithromycin increased from 0.06-0.125 to 1-4 mg/L. The clindamycin MIC increased from 0.125-0.25 to 8 mg/L. Penicillin G and amoxicillin MICs increased from <1 mg/L to 128-512 mg/L. Isolates made resistant to one fluoroquinolone exhibited cross-resistance to the other quinolones except the ST-1 mutant strain which remained susceptible to garenoxacin. Cross-resistance to fluoroquinolones did not correlate with resistance to other antibiotics. CONCLUSION: The ease with which B. anthracis can be made resistant in vitro suggests that close monitoring of patients treated for anthrax is mandatory.

In vitro post-antibiotic effect of fluoroquinolones, macrolides, beta-lactams, tetracyclines, vancomycin, clindamycin, linezolid, chloramphenicol, quinupristin/dalfopristin and rifampicin on Bacillus anthracis.

OBJECTIVES: The aim of this study was to investigate in vitro the post-antibiotic effect (PAE) of 19 antibacterial agents against two strains of Bacillus anthracis (ST-1 and Sterne strains). METHODS: PAE was determined by calculating the time required for the viable counts of antibiotic-exposed bacteria (at concentrations of 10x MIC and exposure for 2 h) at 37 degrees C to increase by 1 log10 above the counts observed immediately after antibiotic removal compared with the corresponding time for controls not exposed to antibiotics. RESULTS: The PAEs of the fluoroquinolones (ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin and garenoxacin) were 2-5 h. The macrolide (erythromycin, clarithromycin and telithromycin) PAEs were 1-4 h, and that of clindamycin was 2 h. The PAEs induced by tetracycline and minocycline were 1-3 h. The PAEs induced by the beta-lactams (penicillin G, amoxicillin and ceftriaxone), vancomycin, linezolid and chloramphenicol were 1-2 h. The PAE induced by rifampicin was 4-5 h. Quinupristin/dalfopristin had the longest PAE, lasting for 7-8 h. CONCLUSIONS: Our results indicate that the PAE is unrelated to the MIC but may be related to the rapidity of bacterial kill. These observations may bear importance on treatment regimens of human anthrax.

In vitro susceptibility of Bacillus anthracis to various antibacterial agents and their time-kill activity.

OBJECTIVES: To investigate the in vitro acquisition of resistance to antibiotics by Bacillus anthracis. METHODS: The in vitro activities of 18 antibacterial agents against two strains of B. anthracis, the Sterne strain and the Russian anthrax vaccine strain ST-1, were tested by determining the MICs and by measuring the rates of antibiotic kill at 5x and 10x MIC. RESULTS: The fluoroquinolones ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin, the beta-lactams penicillin G and amoxicillin, the macrolide clarithromycin, the ketolide telithromycin, as well as clindamycin, rifampicin and quinupristin/dalfopristin had MICs in the range of 0.03-0.25 mg/L. Minocycline had an MIC of 0.03 mg/L, as did penicillin, against the ST-1 strain. Ciprofloxacin had an MIC of 0.03 mg/L against both strains. Erythromycin, vancomycin and the oxazolidinone linezolid were less active (MIC 0.5-2.5 mg/L). Ceftriaxone was the least active, having an MIC of 8.0 mg/L. Chloramphenicol was inactive (MIC > 256 mg/L). Quinupristin/dalfopristin, rifampicin and moxifloxacin showed the most rapid bacterial killing, achieving a complete eradication of detectable organisms (2 log(10) reduction within 0.5-3 h and 4 log(10) reduction within 0.5-4 h for both strains at concentrations of 5x and 10x the MIC). The beta-lactams and vancomycin demonstrated a 2-4 log(10) reduction within 5-15 h. Ceftriaxone had a similar effect to penicillin and amoxicillin against the ST-1 strain, but a slower effect than these two beta-lactams against the Sterne strain. The macrolides, tetracyclines and linezolid demonstrated a lower kill rate, while chloramphenicol did not kill at all. CONCLUSIONS: These data expand on the spectrum of agents recommended for the treatment of anthrax (ciprofloxacin, penicillin G and tetracyclines) and add new options, such as other fluoroquinolones, amoxicillin, rifampicin and quinupristin/dalfopristin, as potential therapeutic agents.