Pretreatment of clinical specimens with sodium dodecyl (lauryl) sulfate is not suitable for the mycobacteria growth indicator tube cultivation method

Abstract

When using the Mycobacteria Growth Indicator Tube (MGIT), pretreatment of clinical specimens with N-acetyl-L-cysteine-NaOH is recommended by the manufacturer. Processing of clinical specimens (n ‫؍‬ 1,000) with sodium dodecyl (lauryl) sulfate-NaOH resulted in both poor recovery and delayed mean time to detection of acid-fast bacilli. Values were comparable to those obtained on solid media.Recently, a hitherto-nonautomated new culture technique, the Mycobacteria Growth Indicator Tube (MGIT; Becton Dickinson Microbiology Systems, Cockeysville, Md.), has been developed to circumvent commonly observed problems associated with radiometric detection systems, such as the potential danger of needle puncture and the accumulation of radioactive waste. The MGIT, which contains modified Middlebrook 7H9 broth in conjunction with a fluorescence quenching-based oxygen sensor, can be used for both rapid detection of acid-fast bacilli (AFB) (3) and susceptibility testing (7). Zuhre Badak et al. (10) reported rates of recovery of 90 and 82% for Mycobacterium tuberculosis and M. avium complex, respectively, by this system, in contrast to 93 and 85% by the BACTEC 460 (BACTEC 460 TB system; Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.). A recent European multicenter study including 1,500 clinical specimens which had been pretreated with N-acetyl-L-cysteine (NALC)-NaOH demonstrated that there was no statistically significant difference (P Ͼ 0.05) between a combination of the MGIT and solid media and a combination of the BACTEC 460 and solid media in detecting mycobacteria (6). The mean times to detection of M. tuberculosis complex were 9.9 days with the MGIT, 9.7 days with the BACTEC 460, and 20.2 days with solid media, while on average, 11.9, 13.0, and 22.2 days were needed for nontuberculous mycobacteria (NTM) to appear when these three methods were used.According to the manufacturer of the MGIT, clinical specimens have to be pretreated with NALC-NaOH (2). At present, little is known about the efficacy of the new cultivation technique when specimens have been pretreated by procedures other than the NALC-NaOH method. In two independent studies, sodium dodecyl (lauryl) sulfate (SDS)-NaOH, which is less commonly applied in the United States than in European countries, has proven to be an efficient alternative in eradicating rapidly growing contaminants in clinical specimens (1,9). A modified SDS-NaOH procedure yielded even higher rates of detection of mycobacteria than did NALC-NaOH in the BACTEC 460 and on Löwenstein-Jensen (LJ) slants (82 and 76%, respectively, for SDS-NaOH-treated specimens and

Rapid detection of mycobacteria in clinical specimens by using the automated BACTEC 9000 MB system and comparison with radiometric and solid-culture systems

“…Another factor directly influencing culture sensitivity is the method of pretreatment of clinical specimens. As shown recently for the new MGIT medium, NALC-NaOH treatment is significantly superior to decontamination with sodium dodecyl (lauryl) sulfate-NaOH (11).…”

Evaluation of OMNIgene®•SPUTUM reagent for mycobacterial culture

“…13 It is well established the SDS is not compatible with the MGIT system 150 due to its strong binding to proteins present in the medium which can in turn impair 151 mycobacterial growth (and possibly that of other bacteria). 14 Our study did not show any benefit of OMNIgene ® SPUTUM reagent over NALC-NaOH with 173 regards to contamination. This is in contrast with the findings from other studies reporting lower 174 culture contamination rates when using OMNIgene ® SPUTUM reagent.…”

“…4 Respiratory samples are 12 therefore specially treated, a process called 'decontamination' before inoculation and incubation 13 of broth and solid media. Decontamination and the supplementation of broth and media with 14 antibiotics and antifungals are intended to prevent overgrowth of the slower growing 15 mycobacteria by concomitant flora of specimens from non-sterile sites. Decontamination 16 procedures aim at decreasing viability of gram-positive and -negative bacteria and fungi while 17 interfering as little as possible with mycobacterial viability and growth.…”

Rapid culture-based diagnosis of pulmonary tuberculosis in developed and developing countries

“…Oxalic acid (ethanedioic acid, 5%) yields results similar to sodium lauryl sulfate, NALC–NaOH and 6%-sulfuric acid (Pathak and Deshmukh, 1973 ) which can be used for heavily contaminated specimens, including Pseudomonas species (Pfyffer et al, 2003 ). Sodium lauryl sulfate decontamination is effective (Langerová and Tacquet, 1968 ) but treated specimens should not be inoculated in liquid medium (Pfyffer et al, 1997 ) and are inappropriate for PCR-based assays (Zingué et al, 2013 ). Therefore, sodium lauryl sulfate is no longer used for decontamination.…”