74. Clinical case, young homeless man, HIV+.You are working at the community clinic when a young, HIV+, homeless man presents with fever,fatigue and a cough of 6 months duration.You Gram stain a sample of his sputum and examine with your microscope, you see faintly stainingbacilli in cords. You next perform an acid-fast stain on the sputum and see red staining bacilli incords.Question: The reason the pathogen did not stain well with the Grams stain is because of thethick hydrophilic capsulethick, waxy, hydrophobic cell wallO thick, hydrophilic cell membraneO thick layer of hydrophobic peptidoglycan

Mycobacterium tuberculosis (MTB) and human immunodeficiency virus (HIV) co-infection has been causing major havoc in public health globally. According to the World Health Organization (WHO), almost 15% of patients diagnosed with MTB were HIV positive and a total of 360,000 deaths resulted from MTB-HIV coinfection alone. Tubercule bacilli TB are spread through air from one infected person to another. The cell wall in the a bacterium provides a protective structure. For mycobacteria, the cell envelope possess unusual membrane lipids, which are called mycolic acids. There is a hydroxyl acid backbone along with two hydrocarbon chains. The cell wall lipids in case of acid-fast organisms are responsible for cell wall formation and they determine cell wall thickness, and affect virulence, protective and immune activities of the organisms. Therefore the answer is: Thick, waxy, hydrophobic cell wall.