Comparison of the manual Mycobacteria Growth Indicator tube and the Etest with the method of proportion for susceptibility testing of Mycobacterium tuberculosis.

BACKGROUND: Clinical microbiology laboratories should provide reliable results on susceptibility testing of Mycobacterium tuberculosis to different agents. METHODS: The manual Mycobacteria Growth Indicator Tube (MGIT) and Etest were compared to the method of proportion (MOP) for susceptibility testing of 88 clinical isolates of M. tuberculosis against isoniazid (INH), rifampin (RIF), streptomycin (STR) and ethambutol (EMB). Isolates were recovered from different patients and were identified at species level by PCR and hybridization. RESULTS: Resistance to INH was detected in 20.5, 29.5 and 12.5% of the isolates, followed by STR resistance (19.3, 26.1 and 1.1%), RIF (9.1, 4.5 and 5.7%) and EMB (2.3, 11.4 and 2.3%) by the MOP, MGIT and Etest, respectively. Sensitivity of the manual MGIT ranged from 37.5% for RIF resistance to 100% for EMB, while Etest sensitivity ranged from 5.9% for STR to 62.5% for RIF. CONCLUSIONS: MOP remains the method of choice, with the manual MGIT showing superior sensitivity at detecting resistance to INH, STR and EMB compared to the Etest.

Resistance of Mycobacterium tuberculosis isolates in different populations in Greece during 1993-2002.

OBJECTIVE: To document the prevalence of resistance of Mycobacterium tuberculosis to isoniazid (INH), rifampicin (RMP) and both combined (multidrug resistance [MDR]) in Greece from 1993 to 2002. DESIGN: We studied a single sputum sample per patient from 4108 patients referred to the Greek National Referral Centre for Mycobacteria. Patients were divided into native Greeks, immigrants and repatriated Greeks originating from the former Soviet Union. Prior treatment status was not recorded. RESULTS: A statistically significant increase in resistance to INH and RMP and MDR was noted comparing the years 1993-1997 to 1998-2002 (P < 0.0001). Resistance to INH and RMP and MDR rose from 5.6% to 7.71%, from 1.57% to 4.49% and from 1.23% to 3.98%, respectively, among native Greeks and from 23.63% to 32.91%, from 6.36% to 15.19% and from 6.36% to 13.92% among repatriated Greeks. Smaller changes were seen among immigrants (from 15.43% to 9.57% for INH, from 5.51% to 6.12% for RMP and from 5.71% to 5.32% for MDR). CONCLUSION: We documented an increase in M. tuberculosis resistance to INH and RMP, and MDR. This was mainly limited to native and repatriated Greeks. Although this is likely the result of immigration and of mismanagement of index cases in Greece, molecular methods are needed to better describe the situation.

Multicenter evaluation of the fully automated bactec MGIT 960 system and three molecular methods for the isolation and the identification of mycobacteria from clinical specimens.

A combination of Bactec MGIT 960 system, a PCR-based assay and a PCR-Restriction Analysis procedure (PRA) was assessed for the detection and identification of mycobacteria from clinical samples. The MGIT recovered 243 from 266 mycobacterial isolates. The PCR-based assay correctly identified all (234) Mycobacterium tuberculosis isolates, while 35 nontuberculous mycobacterial isolates were identified by PRA.

Detection of mycobacteria in clinical specimen using the mycobacteria growth indicator tube (MGIT) and the Lowenstein Jensen medium.

The recovery rates of mycobacteria strains isolated from 1200 clinical specimens using the mycobacteria growth indicator tube (MGIT) system and the conventional Lowenstein Jensen medium (LJ) were assessed. Of the 87 mycobacterial isolates recovered, 54 belonged to the M. tuberculosis complex (MTB) and 33 to the non-tuberculosis complex (NTM). MGIT recovered 78 (89.65%) mycobacteria isolates (51 MTB (94.44%) and 27 NTM (81.81%) and LJ recovered 70 (80.46%) mycobacteria isolates (49 MTB (90.74%) and 21 NTM (63.63%). Sixty one (70.1%) of the total mycobacteria isolates were recovered with both systems (46 (85.2%) MTB and 15 (45.5%) NTM). No significant difference was found between MGIT and LJ (p > 0.05) in both MTB and NTM recoveries. The average detection time for MTB was significantly shorter with MGIT than with LJ, in both the smear-positive specimens (8 vs 30 days: p < 0.0001) and smear-negative specimens (15 vs 30 days: p < 0.001). The average detection time of NTM was also shorter for MGIT (15 vs 30 days: p < 0.0001). However, the contamination rate was higher in MGIT (8.5%) than in LJ (3%). The results suggest that the use of MGIT contributes to a more rapid and effective diagnosis of mycobacterial infections particularly when combined with the classical LJ.

Molecular markers for the investigation of Mycobacterium gordonae epidemics.

Mycobacterium gordonae was isolated as a light growth from bronchoalveolar aspirates from nine patients over 12 months. All patients were in one hospital, and had been bronchoscoped for suspected malignancy. None of the patients had symptoms or radiographic findings of mycobacterial infection. The isolates were characterized by biochemical tests and molecular hybridization. Random amplified polymorphic DNA analysis (RAPD) was used to test whether the strains had a common origin. All the isolates generated four to eight fragments, and almost all presented distinct RAPD patterns. Antimicrobial resistance patterns to six agents confirmed that the isolates were unrelated. Thus epidemiologically unrelated strains of M. gordonae can exist as contaminants in the same department over a relatively short time frame. RAPD analysis is easy to perform, gives rapid results, and can be used for epidemiological analysis of M. gordonae isolates.

The effect of intraarticular hydrocortisone injection on the articular cartilage of rabbits.

We investigated the effect of hydrocortisone on the articular cartilage of the knee in rabbits. 27 New Zealand white rabbits were injected intraarticularly with 25, 50 or 100 mg betamethasone acetate in 2 or 4 weekly intervals. Control animals were injected with normal saline and demonstrated no histological changes in the articular cartilage. Hydrocortisone administration was associated with increased cell size, as well as an increased stain density in the cytoplasm surrounding vacuoles. In addition, loss of cell organelles was also observed. High dose of hydrocortisone was associated with an obvious loss of cell shape and distortion of the cell membrane and nucleus. The magnitude of histological changes, found under light and electron microscopy, were proportional to the amount of hydrocortisone injected. Our findings strongly indicate that intraarticular injection of hydrocortisone alters the shape of articular cartilage chondrocytes, producing abnormal changes in the cytoplasm and nucleus and leading to cell degeneration.

Clinical assessment of primary digital nerve repair.

We have carried out a retrospective study of 64 primary digital nerve repairs in 50 patients who presented to our department between 1988 and 1993. 45 of the patients were operated on within 6 hours of the injury using microscope (x 14). Normal two-point discrimination was regained in only 9 cases, while 6-10 mm two-point discrimination was achieved in 22, 11-15 mm in 15 and protective sensation in 18. A close correlation between age and recovery of sensation after repair was observed. Microsurgical repair of digital nerve gives satisfactory results, since a normal or good two-point discrimination can be obtained in about half of cases, while sensation improves in the rest. A high rate of complete recovery of sensation, however, is to be expected only in children.

Major amputation of the upper extremity. Functional results after replantation/revascularization in 47 cases.

Over a 7 year period, 47 patients underwent replantation of complete (19) and revascularization of incomplete nonviable (28) amputations of the upper extremity. Revascularization of incomplete nonviable amputations had a success rate of 100 percent, where as replantation of complete amputations had a success rate of 74 percent. 37 of the 42 patients with successful replantations had satisfactory functional use of the replanted extremity.

Mid-palm replantation. Long-term results.

16 patients with complete mid-palm amputations underwent replantation between 1987 and 1991. 14 were successful. Young patients with guillotine type mid-palm amputations who could be treated with end-to-end suturing of the tendons and nerves, presented with the highest degree of function when evaluated both objectively and subjectively. In contrast, less return of function was noted in patients with high energy or avulsion type injuries of the nerves.

Microsurgical reconstruction of large nerve defects using autologous nerve grafts.

Between 1986 and 1993, 643 patients with peripheral nerve trauma were treated in our clinic. Primary neurorraphy was performed in 431 of these patients and nerve grafting in 212 patients. We present the functional results after nerve grafting in 93 patients with large nerve defects who were followed for more than 2 years. Evaluation of function was based on the Medical Research Council (MRC) classification for motor and sensory recovery. Factors affecting functional outcome, such as age of the patient, denervation time, length of the defect, and level of the injury were noted. Good results according to the MRC classification were obtained in the majority of cases, although function remained less than that of the uninjured side.

Results after repair of traumatic arterial damage in the forearm.

Eighty-three patients, with 96 instances of radial or ulnar arterial damage, were treated over a four-year period using microsurgical techniques. Thirty-one patients, with 43 arterial repairs, were available for evaluation. In the 14 patients with a single arterial repair, 4 resulted in thrombosis (71.5% success rate). When both arteries required repair, our success rate was 75.9%, with 7 thromboses. The overall success rate was 74.5%. We attribute the high patency rate to strict microsurgical technique, the repair of the vessels in the early stages after trauma, and the use of vein grafts after complete resection of the damaged portion of the vessel.

Clinical analysis and evaluation of the function of replanted and revascularized parts of the upper limb.

During the past four years, we have attempted to replant and revascularize 57 hands and fingers in 43 patients. The total success rate was 81%. Replantation of hands severed cleanly (guillotine type) and those with slight local crush injuries had the highest success rate. As for hand function, amputations at zones III and IV with end-to-end suturing of the tendons and nerves presented the highest degree of function when evaluated objectively and subjectively. All patients presented a high degree of satisfaction with the outcome of the operation.