Question

QUESTION 28

1. Which of the following is a presumptive test for the identification of Lancefield group A Streptococcus?

   	a.	Bacitracin susceptibility
   	b.	positive coagulase
   	c.	hippurate hydrolysis
   	d.	gram stain

1 points   

QUESTION 29

1. An organism grew at 37⁰C and 42⁰C from a stool culture oxidase, catalase, and Hippurate positive. This organism would be identified as:

   	a.	Campylobacter coli
   	b.	Campylobacter jejuni
   	c.	Streptococcus pneumoniae
   	d.	Aeromonas hydrophila

1 points   

QUESTION 30

1. A group of Canadian travelers were visiting the island of Kauai in Hawaii for a summer vacation. They noticed a cave in the middle of the island that contained a 10 feet deep pool of water. Much to their surprise, they were the only individuals enjoying this newly discovered swimming hole. A few days later, all swimmers became ill. Their physician believed they all had Weil disease. Which of the following organisms could cause this disease?

   	a.	Chlamydia trachomatis
   	b.	Treponema pallidum
   	c.	Borrelia burgdorferi
   	d.	Leptospira interrogans

Answer 1

28. The correct answer is a.

Basically, bacteria cell walls have a peptidoglycan cell layer. So, bacitracin is an antibiotic that interferes with the synthesis of the peptidoglycan layer. Different bacteria have different susceptibility towards this interference. Bacterium susceptibility test is to determine whether the bacterium is susceptible to that specific bacterium or not.

Lancefield group A consists of one bacteria that is Streptococcus pyrogens. This bacteria is nonmotile, non sporing cocci, and gram-positive in nature. As a presumptive test of Streptococcus pyrogens, bacitracin susceptibility test is done to distinguish it from other types of beta-hemolytic streptococcus bacteria.

29. The correct answer is b.

Campylobacter jejuni grows well at 42 degree celsius. They are aerobic which means they use oxygen for the respiration process and hence they are oxidase positive. They can asl neutralize the harmful effects of hydrogen peroxide and they are catalase positive. Also , this organism can hydrolyze hippurate where in turn benzoic acid and glycine are formed which means they are hippurate positive.

Campylobacter coil is a hippurate negative

Streptococcus pneumonia is oxidase and catalase-negative.

Aeromonas hydrophila is oxidase-positive, catalase-positive but they are hippurates negative.

30. The correct answer is d

First, all the swimmers were believed to have Weil disease. This is an infectious disease which is caused by leptospira bacteria causing leptospirosis disease. These are gram-negative motile organisms that are present abundantly in swimming pools. Humans get infected when they come in contact with the infected animal's urine either directly or indirectly through the water. It causes liver and kidney damage.

Treponema pallidum causes syphilis which can enter our body through cuts, brake, or via a mucous membrane. This occurs via sexual transmission i.e oral or anal sex and bacteria cannot infect via swimming pools i.e water.

Borrelia burgdorferi is transmitted via tick bites.

Chlamydia trachomatis causes eye infections that their mode of transmission is sexual.