Mariuccia Scagnelli

Comparison of MB/BacT ALERT 3D System with Radiometric BACTEC System and Löwenstein-Jensen Medium for Recovery and Identification of Mycobacteria from Clinical Specimens: a Multicenter Study

ABSTRACT The MB/BacT ALERT 3D System (MB/BacT) (Organon Teknika, Boxtel, The Netherlands) is a fully automated, nonradiometric system with a revised antibiotic supplement kit designed for the recovery of mycobacteria from clinical specimens. In a multicenter study, the recovery rate of acid-fast bacilli (AFB) and the mean time to their detection from clinical specimens was determined by using the MB/BacT system. Data were compared to those assessed by the radiometric BACTEC 460 system (B460) and by culture on Löwenstein-Jensen (L-J) solid medium. A total of 2,859 respiratory and extrapulmonary specimens were processed by the N-acetyl-l-cysteine (NALC)-NaOH method using two different concentrations of sodium hydroxide; 1.5% was adopted in study design A (1,766 specimens), and 1.0% was used in study design B (1,093 specimens). The contamination rates for MB/BacT were 4.6% (study design A) and 7.1% (study design B). One hundred seventy-nine mycobacterial isolates were detected by study design A, with 148 Mycobacterium tuberculosis complex (MTB) isolates and 31 nontuberculous mycobacteria (NTM) isolates. Overall recovery rates were 78.8% for MB/BacT (P = 0.0049), 64.2% for L-J (P < 0.0001), and 87.1% for B460, whereas they were 84.5, 70.9, and 91.2%, respectively, for MTB alone. A total of 125 mycobacteria were detected by study design B, with 46 MTB and 79 NTM. Overall recovery rates by the individual systems were 57.6% (P = 0.0002), 56.8% (P = 0.0001), and 80% for MB/BacT, L-J, and B460, respectively, whereas the rates were 91.3, 78.3, and 97.8% for MTB alone. By study design A, the mean times to detection of smear-positive MTB, smear-negative MTB, and NTM were 11.5, 19.9, and 19.6 days, respectively, with the MB/BacT; 8.3, 16.8, and 16.6 days, respectively, with the B460; and 20.6, 32.1, and 27.8 days, respectively, with L-J medium. By study design B, the mean times were 15.1, 26.7, and 26 days with the MB/BacT; 11.7, 21.3, and 24.8 days with the B460; and 20.4, 28.7, and 28.4 days with L-J medium. Identification was attempted by probing (Accuprobe) MB/BacT-positive bottles within the first working day following instrument positive flag. Results were compared to those obtained in the B460 positive vials by thep-nitro-α-acetylamino-β-hydroxypropiophenone (NAP) test (study design A) or by the Accuprobe assay (study design B). About 90% of MTB and 100% of NTM could be identified, showing turnaround times closely related to those obtained by combining B460 and the NAP test or the Accuprobe assay. In conclusion, even though recovery rates were shown to be lower than B460, especially for NTM, and contaminants were somewhat higher, MB/BacT represents a valuable alternative to the radiometric system, especially in those laboratories where disposal of radioactive waste is restricted. Finally, when AFB are cultured in nonradiometric liquid media, our data (detection times and bacterial overgrowth rates) suggest that decontamination with 1.5% NaOH may be more suitable than the standard NALC-NaOH.

Investigation of a Q-fever outbreak in Northern Italy

AbstractObjectives: A study was conducted to evaluate the extent of a Q-fever epidemic through active case finding in the area of Vicenza (northeastern Italy), and to identify risk factors for Q-fever in this outbreak. Methods: 1) Descriptive epidemiology; 2) Seroepidemiological survey; 3) Case-control study. 1) Epidemic curve and maps with the location of cases. Identification of the road followed by the flocks of sheep. 2) Cross-sectional study on humans and flocks of sheep tested for anti-Coxiella burnetii antibodies. 3) Cases were defined by the presence of fever > 38 °C plus serological confirmation. Controls were 94 apparently healthy individuals attending outpatient facilities for control visits or certification, group-matched by geographical area, age and gender. A standardized questionnaire was administered by trained interviewers. Odds ratio and 95% confidence intervals (CI) were used to evaluate risk factors for Q-fever. Results: A total of 58 cases were identified in a 5-month period. Male to female ratio was 2.8:1; mean age was 42 years (range: 20–65 years). Twenty-eight patients (48%) were hospitalized. Fever was accompanied by asthenia (81%), headache (76%), chills (72%), and myalgia and arthralgia (53%); cough was present in 47% of patients. Rx abnormalities were found in 81 % of the patients undergoing chest X-ray. Among 111 apparently healthy family members who underwent serological testing, four (3.6%) had antibodies to Coxiella burnetii. Three flocks which passed through the outbreak area between late May and early June were shown to be infected, with prevalence of antibodies ranging between 45 and 53%. The case-control study showed a significant association with exposure to flocks of sheep (Odds ratio = 6.1; 95% CI 2.5, 16.3). Other potential risk factors were not more commonly reported by cases with respect to controls. Conclusions: Indirect exposure to flocks of sheep was a determinant of this outbreak of Q-fever. This finding suggests that transmission occurred through inhalation of contaminated airborne particles. The importance of control measures should be stressed in areas traversed by flocks of sheep.

Efficacy of 7 day lansoprazole-based triple therapy for Helicobacter pylori infection in elderly patients.

Background: The prevalence of Helicobacter pylori increases with age. However, data regarding the effects of anti‐H. pylori treatments in the elderly are very scarce.

Cure of Helicobacter pylori infection in the elderly : effects of eradication on gastritis and serological markers

Background: Specific data on anti‐H. pylori treatments in elderly people are very scarce. The aim of the study was to evaluate in the elderly the efficacy of different anti‐H. pylori therapies and the behaviour of serum anti‐H. pylori antibodies, pepsinogen A and C, and PGA/PGC ratio induced by the anti‐H. pylori treatment.

Multicenter Evaluation of the MB-Redox Medium Compared with Radiometric BACTEC System, Mycobacteria Growth Indicator Tube (MGIT), and Lowenstein-Jensen Medium for Detection and Recovery of Acid-Fast Bacilli

MB-Redox is a new manual culture system designed for the recovery of mycobacteria from clinical specimens. It consists of a liquid medium (modified Kirchner medium) containing a redox indicator, a colorless tetrazolium salt, which is reduced to colored formazan by actively growing mycobacteria. Acid fast bacilli (AFB) are easily detected in the medium as pink to purple pinhead-sized particles. We report the results of a multicenter study (involving four Italian microbiology laboratories processing 2370 clinical specimens) aiming to evaluate the recovery rates of AFB and time required for their detection by using the MB-Redox medium. Two different protocols were set up: in Protocol A (1580 specimens) the performance of MB-Redox was compared with those of the radiometric BACTEC 460 TB system (B460) and Löwenstein-Jensen medium (L-J), whereas in Protocol B (790 specimens) it was compared with those of the Mycobacteria Growth Indicator Tube (MGIT) and L-J. A total of 213 mycobacteria were recovered, including 172 Mycobacterium tuberculosis complex (MTB) isolates and 41 nontuberculous mycobacteria (NTM) isolates. In Protocol A, recovery rates were 81% for MB-Redox system, 84% for B460 system, and 77% for L-J. In Protocol B the recovery rates by individual system were 87, 83, and 76% for MB-Redox, MGIT, and L-J, respectively. Differences in both the protocols were not statistically significant. The MB-Redox system plus L-J (Combination 1) recovered 94% of the isolates in Protocol A and 93% in Protocol B, while B460 plus L-J (Combination 2) and MGIT plus L-J (Combination 3) detected 91 and 89% of all mycobacteria isolates respectively. No statistically significant differences were found among the combinations. The mean time to detection of mycobacteria was 16.3 days in Protocol A and 19.1 days in Protocol B with the MB-Redox system, 22.4 and 25.9 days with L-J, 13.2 days with B460, and 18.2 days with MGIT. The contamination rates were 2.1, 2.0, 1.9, and 3.6 for MB-Redox, B460, MGIT, and L-J respectively. The MB-Redox is a reliable, nonradiometric system for growth and detection of mycobacteria. When used in combination with a solid medium it proved to be an effective replacement for B460. The MB Redox system is a labor-intensive method requiring much handling during the visual reading procedures.

H. pylori infection in HIV-positive patients : A serohistological study

Sixty-seven consecutive patients infected withthe human immunodeficiency virus (HIV-1), 72% of whichwith overt AIDS, were examinated by upper endoscopy dueto various indications and evaluated for the prevalence of H. pylori infection. Theinfection was studied by performing both histologicalexamination of gastric biopsies and serological testingfor anti-H. pylori IgG antibodies. The H. pyloriprevalence rate was 55% in histology; no significantdifferences were observed in HIV-infected subjects andthose with overt AIDS (52% vs 63%, respectively; P =NS). Positive histological testing appeared to bedirectly related to the peripheral CD4+lymphocyte count (minimum rates of 43% were detected in6 patients with CD4+ < 100 ×106/liter and maximum rates of 78% inpatients with CD4+ > 200 ×106/liter, respectively; P < 0.05) and inversely related to the frequency ofantibiotic treatments performed over the six monthsprior to endoscopy. Low CD4+ counts were alsoapparently associated with low-grade H. pyloriinfection. Serological testing was positive for anti-H. pylori IgGantibodies in 39% of patients; compared to histology,serology displayed a sensitivity of 57% and aspecificity of 81%. The discrepancy between histologicaland serological positive results for H. pylori wasnoted to be higher in the more advanced phases of HIVinfection. Based upon our results, the serologicaltesting for anti-H. pylori IgG antibodies seems to require cautious interpretation in HIV-positivepatients.

In vitro activity of rifabutin against strains of Helicobacter pylori resistant to metronidazole and clarithromycin

In vitro activity of rifabutin against strains of Helicobacter pylori resistant to metronidazole and clarithromycin

The Clinical Usefulness of Serum Pepsinogens, Specific IgG Anti-HP Antibodies and Gastrin for Monitoring Helicobacter pylori Treatment in Older People

OBJECTIVE: to evaluate the clinical usefulness of Pepsinogen A (PGA) and C (PGC), PGA/PGC ratio, gastrin, and specific IgG anti‐HP antibodies (anti‐HP Ab) in monitoring the effect of cure for Helicobacter pylori (HP) infection in older people.

Detection of Chlamydophila pneumoniae DNA in peripheral blood mononuclear cells of blood donors in the north-east of Italy

Abstract. Recent studies have implicated Chlamydia pneumoniae (now Chlamydophila pneumoniae) in the pathogenesis of atherosclerosis and demonstrated its presence within human peripheral blood mononuclear cells (PBMCs). In this study the presence of C. pneumoniae DNA was assessed, using nested PCR, in PBMCs from 169 active blood donors as a function of age, of specific antibodies and C-reactive protein. The results obtained demonstrated a high degree of global positivity (46.15%), which was higher in females (52%) than in males (43.7%). Seroepidemiological studies showed a high percentage of positivity both in subjects positive by PCR (65.91%) and negative by PCR (71.74%). The clinical implication of such finding are under study.

Evaluation of the DipStreak, a New Device with an Original Streaking Mechanism for Detection, Counting, and Presumptive Identification of Urinary Tract Pathogens

ABSTRACT DipStreak is a new urine culture device with two types of agar attached back-to-back on a plastic paddle. It combines dip-slide technology and an original streaking inoculation mechanism, allowing for bacterial counting and colony isolation. The performance of the DipStreak device with two different medium formulations, CHROMagar and MacConkey media in study A and UriSelect 3 and MacConkey media in study B, was evaluated and compared to that of the reference streak method by using plates of cystine-lactose-electrolyte-deficient (CLED) agar, tryptic soy agar with 5% sheep blood, and UriSelect 3 medium. In study A, 2,000 urine specimens were processed and 511 cultures were found positive. The DipStreak device and the UriSelect 3 and CLED medium plates gave the same detection rate, 99.7%. For the direct identification of Escherichia coli, Proteus mirabilis, and Enterococcus sp. isolates, the DipStreak device and the UriSelect 3 medium plate showed overall sensitivities of 97 and 93.4%, respectively. In study B, 3,000 urine specimens were processed and 714 cultures were found positive. The DipStreak device and the UriSelect 3 and CLED medium plates gave detection rates of 99.4, 99.9, and 99.2%, respectively. For the direct identification of E. coli, P. mirabilis, and Enterococcus sp. isolates, the DipStreak device and the UriSelect 3 medium plate showed overall sensitivities of 88 and 94.4%, respectively. In conclusion, the DipStreak device with both medium formulations represents an attractive and excellent screening method for the reliable detection, counting, and presumptive identification of urinary tract pathogens. It enables bedside urine inoculation and provides a valid means of transporting the sample back to the laboratory, decreasing drastically the rate of false-positive results due to bacterial overgrowth and reducing associated costs.