The finding of five to six acid-fast bacilli per field in a carbol fuchsin smear of expectorated sputum should be reported as

• A. 1+
• B. 2+
• C. 3+
• D. 4+

Answer: (C)

The main idea here is that acid-fast smear results are reported on a semi-quantitative scale that reflects how many bacilli are seen, i.e., the burden of infection. When you observe five to six acid-fast bacilli in a single oil-immersion field, that indicates a substantial bacillary load—not just a few scattered organisms, but a heavy presence.

In many standard grading schemes for sputum smears, this level of burden corresponds to the higher category, often described as a heavy smear. Specifically, five to six bacilli per field fits the 3+ designation, which communicates a strong bacterial load but is not the absolute maximum category. A 4+ would denote an even denser appearance, with many fields showing bacilli or an extremely high count per field. Lower grades like 1+ or 2+ indicate progressively fewer bacilli per field.

So five to six bacilli per field is reported as 3+ because it reflects a heavy, significant bacillary burden without reaching the most extreme, widespread density associated with a 4+ designation. This helps clinicians gauge infectiousness and monitor treatment response.