Biological Evidence 2018, Vol.8, No.1, 1-5
3
about 1 to 2 cm. The sputum slides were allowed to air-dried. They were then heat-fixed and subsequently stained
with Ziehl-Neelsen techniques. Each of the sputum smear was flooded with 0.3% strong carbon fuchsin, and it
was heated and allowed to stand for 10 minutes before being dewashed with distilled water. Thereafter, an
acid-alcohol was added for 2 minutes, before being washed off with water and counter-stained with methylene
blue, and then rinsed with water and allowed to dry (Kent and Kubica, 1985).
Furthermore, remaining sputum samples which are approximately 1 to 2 ml were placed in a 15 ml tube with
screw cap containing the same quantity of undiluted household bleach. The mixture of sputum and bleach was
incubated at room temperature undisturbed for half an hour. Then after, a drop of the bleach digested sputum was
transferred to a slide. Again, the bleach smear of about 1 to 2 cm was made, air-dried, heat-fixed and stained with
Ziehl-Neelsen techniques. Both smears (bleached and unbleached) were viewed under light microscope using oil
immersion lens. The resultant characteristics (positive and negative smears) were defined according to the
National Tuberculosis and Leprosy Control Program (NTBLCP) Acid Fast Bacilli (AFB) grading (1978).
2 Results and Discussion
Table 1 presents the effect of bleach on diagnosis of
Mycobacterium tuberculosis
using smear microscopy method.
Sixty (60) sputum samples were analyzed and results revealed that 32 (53.3%) were positive for acid-fast bacilli
using direct microscopy techniques. The sputum that was bleached had same positive results i.e. 32 (53.3%). The
results clearly showed that all sputum smears that were positive to AFB under direct microscopy techniques were
also positive when bleach was applied in the microscopy method. Furthermore, a decrease in the mean number of
AFB observed in a given field when viewed under the microscope. 7 (21.9%) smears graded as + by direct
microscopy appeared scanty and 10 (31.3%) graded as ++ decreased to +. Also, 15 (46.9%) smears graded as +++
decreased to ++.
Table 1 Comparison of direct microscopy and bleach method for the detection of
Mycobacterium tuberculosis
DIRECT MICROSCOPY (n)
BLEACH METHOD (n)
TOTAL NUMBER (n)
60
32
NO INFECTED (NI)
32
32
1-9 AFB in 10 fields (+)
7
SCANTY
1-9 AFB per field (++)
10
+
>10 AFB per field (+++)
15
++
The study validates the findings of previous authors indicating that bleach improves diagnostic smear microcopy
method of tuberculosis (Cattamanchi et al., 2010; Van Deun et al., 2010; Chew et al., 2011). In addition, due to the
disinfectant potentials of bleach, it could be useful in control infection in laboratories lacking biosafety facilities.
Furthermore, bleach can easily disintegrate the bacilli if allowed to act for 60 minutes (Wah et al., 2001; Yassin et
al., 2003; James et al., 2014). Based on this, bleach method of
Mycobacterium tuberculosis
diagnosis is meant for
only microscopy and not sputum intended for culture (James et al., 2014). The bleach smear microscopy showed a
reducing potential on
Mycobacterium tuberculosis
(James et al., 2014). The bleach method is characterized by
high density of AFB in the fields, and decline in debris present in the sample thereby allowing a clear field for
bacteria detection (Wah et al., 2001; James et al., 2001). This lead to reduction in the time needed for microscopy
to be carried out (James et al., 2014).
3 Conclusions
This study assessed the effect of bleach on the diagnosis of
Mycobacterium tuberculosis
in a hospital. The results
revealed that the use of bleach smear microscopy for the diagnosis of
Mycobacterium tuberculosis
is practicable
and could be useful essentially in hospital setting that direct microscopy is not carried out routinely. Therefore, we
recommend that further studies should be carried out to determine other means of harnessing bleach for the proper
diagnosis of tuberculosis.
