Microbiology with Diseases by Taxonomy Chapter 21 Answers

Microbiology with Diseases by Taxonomy Chapter 21 Answers

Microbiology with Diseases by Taxonomy Answers

Microbiology with Diseases by Taxonomy Chapter 21 Answers 1CM
The following concept map describes the sexually transmitted disease syphilis. The causative organism, stages, diagnosis and treatment of syphilis are shown in this concept map.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 1CT
The arthropods like ticks transmit the diseases Rocky Mountain spotted fever and Lyme disease. These diseases are caused by the agents Rickettsia rickettsii and Borrelia burgdorferi respectively.
The treatment for these diseases includes the removal of the tick from the human body. Antimicrobial drugs are effective at the primary stage of the infection. As the disease progresses, they become ineffective because the later symptoms will result from the immune response. Vaccine is available, but it is not widely used as it may cause infection in some patients.
Prevention of the infection involves using tick repellents, tight fitting clothes and covering the body completely. The ticks cannot be eliminated completely as they can survive even for a period of four years without feeding.
Cholera is caused by consuming contaminated water. The causative organism is Vibrio cholerae. A high innoculum is required to cause the infection.
Treatment of cholera includes using antimicrobial drugs and replacing the fluid and electrolytes. A promising oral vaccine is available for cholera.
Prevention and limiting the spread of the disease can be attained by proper hygiene and adequate sewage and water treatment. This causative bacterium is sensitive to drying also. By using any of these, the disease can be controlled.
Thus, it is easy to control cholera than controlling RMSF and Lyme disease (as the ticks cannot be easily prevented).
Hence, it is difficult to rid a community of the disease transmitted by arthropods than that of a disease transmitted by contaminated water.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 1L
The following figure shows the stages and structures of the chlamydia life cycle. The time taken at each step has been indicated.
(6) Elementary body

1. The chlamydial life cycle starts with the attachment of the elementary body (EB) to the host cell.
2. The EB will enter into the host cell by endocytosis.
3. In the host cell, the EB will be converted into a reticulate body (RB). This will take about 10 hrs after infection.
4. The RB will divide rapidly inside the cell. Due to this, more RBs will be produced.
5. The endosome that is completely filled with RBs is called inclusion body.
6. After 21 hrs of infection, the RBs present in the endosome will start converting into EBs.
7. From that after 19 hrs, the EBs will be released from the host cell by exocytosis.
8. Some of these EBs will infect new host cell. Again the chlamydial life cycle will start.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 1M

1. Rocky Mountain spotted fever is a lethal illness, most frequently reported in USA (United States of America). This disease is caused by Rickettsia rickettsii. This bacterium is spread to human by Dermacentor ticks. Hence, this option matches with (C) Rickettsia rickettsii.
2. Endemic typhus is a form of typhus, which is transmitted by fleas. This disease is caused by Rickettsia typhi. It is also called murine typhus. Hence, this option matches with (A) Rickettsia typhi.
3. Epidemic typhus is a form of typhus often causes epidemics following natural disasters and wars. This disease is caused by Rickettsia prowazekii, and is transmitted by the human louse. Hence, this option matches with (B) Rickettsia prowazekii.
4. Scrub typhus is a form of typhus caused by Orientiatsutsugamushi (an intracellular parasite). This bacterium belongs to the family Rickettsiaceae. This disease is transmitted by some species of trombiculid mites. Hence, this option matches with (D) Orientiatsutsugamushi.
5. Human monocyticehrlichiosis (HME) is a form of ehrlichiosis, and is caused by Ehrlichiachaffeensis. This bacterium is an obligate intracellular pathogen that affects macrophages and monocytes. Hence, this option matches with (E) Ehrlichiachaffeensis.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 1MC
Most human infections caused by species of Rickettsia are transmitted through vectors.
(a) Are acquired from fomites:
Fomites like toilet seats, utensils, or clothing cannot transmit the infections caused by Rickettsia. These infections are transmitted by arthropod vectors. Hence, this option is incorrect.
(b) Could be prevented by hand washing:
These human infections cannot be prevented by washing hands. As they are transmitted by vectors like ticks, lice and fleas, they can only prevented by avoiding the vectors. Hence, this option is incorrect.
(c) Are transmitted via vectors:
The infections caused by Rickettsia are transmitted through arthropod vectors. Rocky mountain spotted fever is transmitted by hard ticks. Typhus is transmitted either by human body louse or rat fleas. Hence, this option is correct.
(d) Are sexually transmitted:
The infections caused by Rickettsia are transmitted alone by arthropod vectors. There is no other means for their transmission. Hence, this option is incorrect.
Hence, the correct option is (c) are transmitted via vectors. Most human infections caused by Rickettsia are transmitted through arthropod vectors.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 1SA
Rickettsias have functional genes for protein synthesis, ATP production and reproduction. In such a condition also, they are obligate parasites. To explain this, scientists have proposed several hypotheses.
Obligate parasites are those organisms that complete their life cycles without exploiting a host.
The primary hypothesis is:

• Rickettsias have very leaky cytoplasmic membranes. Due to this, they should lose their cofactors. But, they lose even the small cofactors like NAD⁺, only when they are in a particular environment. That environment should contain equivalent amount of these cofactors. Example for such an environment is cytosol of a cell.
• This hypothesis explains that rickettsias are obligate parasites. That means they require a host cell for the completion of their life cycle.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 2CT
Following are the two primary theories that attempt to find the origin of syphilis.

• According to Columbian theory New World disease syphilis was brought back to Europe by homecoming Spanish explorers – Columbus and Martin Alonso Pinzon. Columbus’s voyages to the Americas took place three years prior to Naples syphilis outbreak of 1494. The Columbian theory is sustained by genetic funding of venereal syphilis and associated bacteria, which found a disease midway between syphilis and yaws in Guyana, South America.
• According to pre-Columbian theory syphilis was present in Europe even prior to the arrival of Europeans in the Americas. In 18th and 19th centuries some scholars believed that the signs of syphilis in its tertiary stage were pronounced by Hippocrates in Classical Greece. However, these claims were not presented for peer review, and the evidence provided to other scientists were not strong enough. According to Douglas W. Owsley many medieval European cases of leprosy, were in actual cases of syphilis. Although it is claimed that syphilis was present in Europe till the homecoming of the diseased sailors of the Columbian voyages, Owsley states that “syphilis probably cannot be “blamed”— on any specific race or geographical area.
• The evidence indicates that syphilis existent in both hemispheres through the prehistoric times. However, it is only by fluke that the Columbus expeditions coincided with the “lepra” that spread into virulence by end of the 15th century.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 2M

1. Rickettsia typhi is transmitted to humans by the vectors rat flea Xenopsylla cheopis and cat flea Ctenocephalides felis. Hence, the correct option is (A) Rat flea.
2. Rickettsia prowazekii is transmitted by human body louse, Pediculis humanus.Hence, the correct option is (B) Body louse.
3. Rickettsia rickettsii is transmitted by hard ticks of the genus Dermacentor. Hence, the correct option is (C) Hard tick.
4. Orientia tsutsugamushi is transmitted by the mites of the genus Leptotrombidium. Hence, the correct option is (D) Mite.
5. Ehrlichia chaffeensis is transmitted by the hard ticks like Lone Star tick, deer tick and the dog tick. Hence, the correct option is (C) Hard tick.
6. Borrelia burgdorferi is transmitted by the hard ticks of the genus Ixodes. Hence, the correct option is (C) Hard tick.
7. Borrelia recurrentis is transmitted by the human body louse Pediculus humanus and by the soft ticks of the genus Ornithodoros. Hence, the correct options are (B) Body louse and (E) Soft tick.
8. Anaplasma phagocytophilum is transmitted by the hard ticks like Lone Star tick, deer tick and the dog tick. Hence, the correct option is (C) Hard tick.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 2MC
The bacterium that causes RMSF is more likely to infect a human when an infected tick feeds for several hours. The bacterium is Rickettsia rickettsii.
(a) If an infected tick feeds for several hours:
Rocky Mountain spotted fever is transmitted through the vector hard ticks. It is transmitted only when the tick feeds the human blood for several hours. In such a condition only, the bacterium gets activated. Hence, this option is correct.
(b) When an infected tick initially penetrates the skin:
The bacterium that causes RMSF gets activated only when the tick feeds on the human blood for several hours. When the tick initially penetrates the skin, the bacterium will be inactive. Thus there will be no chance of infection. Hence, this option is incorrect.
(c) When contaminated tick feces dry and become airborne:
The humans can be infected with RMSF, when they are exposed to the tissues and fluids of crushed ticks or to ticks’ feces. This happens very rarely. But, the infection is never airborne. Hence, this option is incorrect.
(d) If the human is exposed to rodent feces containing the bacterium:
RMSF is transmitted to humans and rodents through hard ticks. In very cases, it is transmitted through crushed ticks or ticks’ feces. It cannot be transmitted through rodent feces, as the bacterium if present in it becomes inactive. Hence, this option is incorrect.
Hence, the correct option is (a) if an infected tick feeds for several hours. The bacterium that causes RMSF is more likely to infect a human when an infected tick feeds for several hours.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 2SA
The bacteria Ehrlichia and Anaplasma are transmitted to the humans by ticks. They enter the blood stream of humans. The bacteria will trigger their own phagocytosis. The phagocytosis is by a white blood cell. That may be either a monocyte or a neutrophil. These bacteria grow and reproduce inside the host cell.
If this phagocytic cell fuses with a lysosome, then there will be a chance of killing the bacteria. Thus, the bacteria will inhibit the fusing of phagosome with the lysosome.
The bacteria undergo three developmental stages inside the phagosome. Once the bacteria enter into the host cell phagosome, it will be called an elementary body. It will contain the host cell wall as its covering. These bodies grow and develop into initial bodies. After reproduction, morula will be formed. It will contain a number of bacterial cells, which are produced due to reproduction. The morula will fuse with the host cellwall. Due to this, the bacterial cells will be released into the blood. By this, they are made available to the feeding ticks.
By feeding such an infected blood, the ticks will transmit the bacteria to another individual.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 3CT
The bacterium responsible for the man’s death might be Vibrio vulnificus.
Vibrio vulnificus is Gram-negative, curved bacilli. They are transmitted by eating raw or uncooked as well as contaminated sea food. They also attack the humans while washing the open wounds with sea water. They are responsible for septicemia.
The symptoms of the infection include vomiting, diarrhea, abdominal pain and blistering skin. As the infection progresses, septic shock and even death may occur. This bacterium is fatal for 50% of untreated patients.
The patient was suffering with severe abdominal pain, diarrhea and fell into coma. After a week, he died. It is known that the patient had sea urchins before he was ill. By this information, it seems that the sea urchins are contaminated with Vibrio vulnificus. This bacterium infected the patient and led him to coma and even death.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 3M

1. Chlamydophila psittaci is a bacterial species that causes ornithosis. It is a bird disease transmitted to the humans. Potential hosts include feral birds, pigs, cattle, sheep etc. Chlamydophila psittaci is transmitter thorough contact, or inhalation. Hence, this option matches with (G) Ornithosis.
2. Chlamydophila pneumoniae is an obligate intracellular pathogen that causes pneumonia, bronchitis and sinusitis in humans. These pathogens have very complex life cycle, as the name indicating they require a host to reproduce. Hence, this option matches with (C) Sinusitis.
3. Chlamydia trachomatis causes sexually transmitted disease called as lymphogranuloma venereum. It also causes ocular disease called trachoma. Besides these, it also causes proctitis and pelvic inflammatory disease. Hence, this option matches with (B) Trachoma, (D) Lymphogranuloma venereum, (E)Proctitis and (F) Pelvic inflammatory disease.
4. Treponema pallidum pallidum belongs to spirochaete bacteria that cause syphilis, which is a sexually transmitted disease. These bacteria have an outer membrane and cytoplasmic membrane. Hence, this option matches with (A) Syphilis.
5. Treponema pallidum pertenue causes yaws, which is characterized by granular lesions. This infection is a tropical infection of the bones, skin and joints. Hence, this option matches with (H) Yaws.
6. Treponema pallidum endemicum causes bejel, which is seen in children. This disease is a chronic tissue and skin disease. This disease is also known as dichuchwa, frenga, skerljevo, belesh etc. Hence, this option matches with (I) Bejel.
7. Treponema carateum causes a skin disease called pinta. It is human skin disease that is endemic to Central America, Mexico, and South America. Hence, this option matches with (J) Pinta.
8. Borrelia burgdorferi belongs to spirochets bacterium, class of the genus Borrelia. It is gram negative bacteria that cause Lyme disease. It is characterized mainly by arthritis. Hence, this option matches with (K) Lyme disease.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 3MC
(a) Rickettsia typhi:
It causes murine typhus. It is usually not fatal. It is not severe. It is transmitted to humans by the vectors rat flea Xenopsylla cheopis and cat flea Ctenocephalides felis. Hence, this option is incorrect.
(b) Rickettsia rickettsii:
It causes Rocky Mountain spotted fever (RMSF). This infection is the most severe and most reported of all the rickettsial infections. Hence, this option is correct.
(c) Orientia tsutsugamushi:
It causes scrub typhus. This infection is endemic. In a very few cases death results due to heart failure. It is not very severe. Hence, this option is incorrect.
(d) Ehrlichia chaffeensis:
It causes human monocytic ehrlichiosis. Only 5% of the cases result in death, if the infection is left untreated. It is not severe as that of RMSF. Hence, this option is incorrect.
Hence, the correct option is (b) Rickettsia rickettsii. The most severe rickettsial infection is caused by Rickettsia rickettsii.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 3SA
Scientists faced problems in identifying the virulence factors of T. pallidum pallidum because the pathogen cannot be cultured. So, the scientists are not able to work out on the pathogen in vitro conditions.
To make it grow in vitro, they used recombinant DNA technology. By this, they inserted the genes of Treponema into E.coli. This made the pathogen to be cultured. Then, they isolated the genes and their respective proteins. After this, the virulence factors of the pathogen are identified.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 4CT
Heliobacter pylori is a urease positive enzyme. Urease degrades urea. Urea is present in the gastric juice. Urea after degradation, it forms into very alkaline ammonia. This ammonia neutralizes the stomach acid. By this, the bacterium gets the access to enter the underlying epithelial cells. Then, the epithelial tissue will be ulcerated. After that, the muscle tissue and blood vessels will be attacked by the bacterium. This is the formation of peptic ulcers.
The mutated Heliobacter pylori is urease negative. So, it cannot degrade urea and produce alkaline condition in the stomach. As and when this mutated bacterium enters the stomach, it gets degraded by the acid in the stomach. Hence, it cannot form peptic ulcers in normal conditions.
This strain causes peptic ulcers only in some patients. In those patients, who consume antacids in large amounts or use drugs to block acid production in the stomach. These drugs decrease the amount of acid in the stomach. Thus, this is an alkaline condition, which favours the bacterium. The mutated bacterium will not be damaged. Hence, this leads to the formation of peptic ulcers in the patients who consume antacids or drugs to block the production of acid.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 4M

1. Peptic ulcers are the erosions of the mucus membrane in the stomach and small intestine. These are caused by the bacterium Heliobacter pylori. Hence, the option matches with (E) Heliobacter pylori.
2. Gastroenteritis is mostly caused by Campylobacter jejuni. Cholera like gastroenteritis is caused by Vibrio parahaemolyticus. Gastritis is caused by Heliobacter pylori. Hence, the option matches with (B) Vibrio parahaemolyticus (D) Campylobacter jejuni and (E) Heliobacter pylori.
3. Blood poisoning is called septicemia. Septicemia is the condition in which there is a presence of microbes or their toxic products in the blood. It is caused by Vibrio vulnificus. Hence, the option matches with (C) Vibrio vulnificus.
4. Cholera is an infection that affects the small intestine caused by Vibrio cholerae. The main symptoms are vomitings and diarrhea. This disease is transmitted primarily by drinking contaminated water or consuming food that is contaminated by the feces. Hence, the option matches with (A) Vibrio cholerae.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 4MC
(a) Rickettsias:
This is genus of nonmotile, non-sporeforming, gram-negative cocci that are obligate intracellular parasites. These are tiny, Gram-negative, obligate, intracellular parasites that live in the cytosol of host cells. Hence, this option is correct.
(b) Mycoplasmas:
These belong to genus of bacteria that lack cell walls. These are small cells, acellular, and free living organisms. Hence, this option is incorrect.
(c) Chlamydias:
These belong to genus of bacteria that are obligate intracellular parasites. These are small, obligate, intracellular parasites that live in endosomes. Hence, this option is correct.
(d) Both a and c:
As the options a and c are correct, this option is correct. Hence, the correct option is (d) both a and c. The smallest cellular microbes are rickettsias and chlamydias.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 4SA
The causative agent of syphilis is Treponema pallidum pallidum. Untreated syphilis has four phases. They are:

1. Primary phase,
2. Secondary phase,
3. Latent phase and
4. Tertiary phase.

In primary syphilis, a small, painless and red colored lesion forms at the site of infection. These lesions are called as chancres. They form in the mouth, around the anus, or on the fingers, lips, nipples, or on the cervix. The center of the chancre will be filled with serum. This serum is very infectious. After three to six weeks, the lesions will disappear. In most of the cases, this will be the end of the disease.
The secondary syphilis starts with the invasion of Treponema into the blood stream. Due to this, the infection spreads all over the body. The symptoms will be sore throat, headache, mild fever, malaise, myalgia, lymphadenopathy and rash. The rash includes the palms and the soles of the feet also. The lesions of this rash will be very infectious. This rash disappears after several weeks or months.
Latent syphilis is clinically inactive. This phase lasts upto 30 or more years. In many cases, the disease will not advance beyond this phase.
Teritiary syphilis is not directly associated with the effects of Treponema. This phase comprises of severe complications, which result from inflammation and hyperimmune response against the pathogen. Any tissue or organ can be affected. This causes dementia, blindness, paralysis, heart failure and syphilitic lesions. These lesions are called as gummas. These are rubbery, painful and swollen lesions that occur in bones, nervous tissue or on the skin.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 5CT
The symptoms of the infection are headache, myalgia and recurring fever. Each fever is last for three days. All the members of the family are infected. This outbreak occurred after the gathering in a remote area. These characteristics say that this disease relapsing fever.
Relapsing fever is caused by Borrelia recurrentis. This is transmitted by either ticks or lice. Hence, the relapsing fever is of two types. They are tick-borne relapsing fever and louse-borne relapsing fever. Both of these have the same symptoms.
Relapsing fever is successfully treated with doxycycline. It is treated with erythromycin in pregnant women and children.
Prevention of relapsing fever involves the avoidance of lice and ticks, use of repellent creams and maintaining good personal hygiene.
The family could be protected itself by maintaining proper hygiene and by taking proper treatment.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 5MC
The most commonly reported sexually transmitted disease in United States is caused by the bacterium Chlamydia trachomatis.
(a) Mycoplasma genitalium :
It is a sexually transmitted disease. It attacks the genital and respiratory tracts. The symptoms are urethritis, arthritis and so on. It may cause pelvic inflammatory disease. This is not a most prevalent disease in United States. Hence, this option is incorrect.
(b) Chlamydia trachomatis :
It is sexually transmitted to result in chlamydial infection. It is the most commonly reported sexually transmitted disease in United States. 1,093,514 cases are reported in 2008. Hence, this option is correct.
(c) Chlamyophila proctitis : This option is not applicable.
(d) Ureaplasma urealyticum :
It is a sexually transmitted. It is associated with urethritis, infertility, premature birth, pneumonia and meningitis. It is not more prevalent in United States. Hence, this option is incorrect.
Hence, the correct option is (b) Chlamydia trachomatis. The most commonly reported sexually transmitted disease in the United States is caused by the bacterium Chlamydia trachomatis.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 5SA
Leptospirosis is caused by Leptospira interrogans. This disease normally occurs in many wild and domestic animals and humans. It is a zoonotic disease. It occurs throughout the world and it is not fatal.
The spread of Leptospira can be controlled in the best way by rodent control. Various rodent control methods can be used to control this disease.
The eradication of this pathogen is impractical, as animals are the reservoirs for this pathogen. An effective vaccine is available for livestock and pets.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 6MC
The disease that is least likely in rural areas of United States is epidemic typhus.
(a) Epidemic typhus:
This infection is caused by Rickettsia prowazekii. It is widely prevalent all around the world. But, it is endemic in Central and South America. Thus, it is found rarely in rural areas of United States. Hence, this option is correct.
(b) Rocky Mountain spotted fever:
It is caused by Rickettsia rickettsii. It is more prevalent in the Appalachian Mountains, Oklahoma, and the southeastern states. Thus, this fever is more prevalent in United States. Hence, this option is incorrect.
(c) Murine typhus:
It is caused by Rickettsia typhi. It is also known as endemic typhus. It is most often seen in the southern United States. Hence, this option is incorrect.
(d) Lymphogranuloma venereum:
It is a sexually transmitted disease caused by Chlamydia trachomatis. It is the most commonly transmitted in the United States. Hence, this option is incorrect.
Hence, the correct option is (a) epidemic typhus. The disease that is least likely in rural areas of the United States is epidemic typhus.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 6SA
V.cholerae O1 E1 Tor causes cholera. It is one of the world’s pernicious diseases.
The humans become infected by the ingestion of contaminated water and food. After entering the digestive system, most of the cells die. This results due to the acidic environment of the stomach. Hence, a high inoculum is required for the disease to develop.
Cholera infections are asymptomatic or cause mild diarrhea. But, some infections result in rapid, severe and fatal fluid. It causes electrolyte lose. The symptoms watery diarrhea and vomiting begin after two to three days of infection. As the days go on, the colon becomes emptied and the stool becomes more watery, colorless and odorless. The stool containing mucus is called rice-water stool.
Some patients may even lose 1 liter of fluid per an hour. Dehydration takes place due to severe fluid and electrolyte lose. Besides this, acidosis, hypokalemia and hypovolemic shocks are caused. These conditions may result in muscle cramping, irregularities in heartbeat, kidney failure, coma and death.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 7MC
Treatment of chlamydial infections involves erythromycin and doxycycline creams as well as surgical correction of eyelid deformities.
The best example of a chlamydial infection is trachoma. It is an eye disease caused by Chlamydia trachomatis.
(a) Erythromycin cream:
Some strains of Chlamydia trachomatis infect the eyes of newborns. This infection is treated with erythromycin cream for 10 to 14 days. Hence, this option is correct.
(b) Doxycycline cream:
Eye infections in adults are caused by the lyphogranuloma venereum strains of C.trachomatis. Such infections are treated with doxycycline cream for 7 days. Hence, this option is correct.
(c) Surgical correction of eyelid deformities:
The abrasion, scaring, and blindness that resulted from ocular infections can be prevented by surgical correction of eyelid deformities. Hence, this option is correct.
(d) All of the above:
As the options (a), (b) and (c) are correct, this option is correct.
Hence, the correct option is (d) all of the above. Treatment of chlamydial infections involve erythromycin cream, doxycycline cream and surgical correction of eyelid deformities.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 8MC
The organism that is transmitted via sexual contact is Treponema pallidum pallidum.
(a) Treponema pallidum endemicum :
It causes the disease bejel. It is transmitted through contaminated utensils. It is a nonvenereal disease. Hence, this option is incorrect.
(b) Treponema pallidum pertenue :
It causes yaws. It is transmitted when the persons come in contact with the fluid that is coming out of the lesions. It is a nonvenereal disease. Hence, this option is incorrect.
(c) Treponema pallidum pallidum :
It causes syphilis. It is transmitted through sexual contact. So, it is a venereal disease. Hence, this option is correct.
(d) Treponema carateum :
It causes pinta. It spreads among children by skin-to-skin contact. It is a nonvenereal disease. Hence, this option is incorrect.
Hence, the correct option is (c) Treponema pallidum pallidum. The organism that is transmitted via sexual contact is Treponema pallidum pallidum.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 9MC
There is no effective vaccine for cholera.
(a) The causative agent lives naturally in marine water:
The causative agent of cholera is Vibrio cholera. This lives naturally in estuarine and marine waters. This is worldwide in distribution. Hence, this option is true about cholera.
(b) There is an effective vaccine for cholera:
A new oral vaccine has been developed for O1 strain of V.cholerae. There is no vaccine for O139 strain. Research is going on for the development of vaccine for cholera. Hence, this option is false about cholera.
(c) Strain O1 E1 Tor has been responsible for several pandemics:
The seventh pandemic began due to the strain O1 E1 Tor. This started in Asia and later spreaded to Africa and Europe. This reached Peru also. Recently, strain O139 was found to be arosing pandemic. No other strain is responsible for pandemics. Hence, this option is true about cholera.
(d) Rice-water stool is a symptom:
As cholera progresses, the stool will be completely filled with mucus. It resembles the water that is poured out from boiled rice. Thus, it is called as rice- water stool. Hence, this option is true about cholera.
Hence, the correct option is (b) there is an effective vaccine for cholera, which is not true of cholera.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 10MC
Penicillin is ineffective at the tertiary stage of syphilis.
(a) Primary syphilis:
After 10-21 days of infection, a reddened lesion called chancre forms. The serum from this lesion will be infectious. This will disappear after three to six weeks. At this stage, penicillin is effective. Hence, this option is incorrect.
(b) Secondary syphilis:
At this stage, a widespread rash that includes even the palms and soles of feet will be formed. The lesions of this rash are infectious. At this stage, penicillin is effective. Hence, this option is incorrect.
(c) Tertiary syphilis:
At this stage, rubbery, painful and swollen lesions called gummas will be formed. This stage may result in heart failure. At this stage, penicillin is ineffective. Hence, this option is correct.
(d) All of the above:
As the options (a) and (b) are incorrect, this option is incorrect.
Hence, the correct option is (c) tertiary syphilis. Penicillin is ineffective during tertiary syphilis.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 11MC
Two weeks after a backpacking trip in Tennessee, a hiker experienced flulike symptoms and noticed a red rash on his thigh. The likely cause of this illness is Borrelia burgdorferi.
(a) Treponema pallidum pertenue :
It causes yaws. It forms large, destructive and draining lesions. These lesions will be formed on the skin, bones and lymphnodes. Hence, this option is incorrect.
(b) Borrelia burgdorferi :
It causes lyme disease. It is characterized by a red rash at the site of infection. The symptoms include malaise, fatigue, fever, chills, pains and lymphadenopathy. These are flulike symptoms. Hence, this option is correct.
(c) Borrelia recurrentis :
It causes relapsing fever. It is characterized by recurrent episodes of septicemia and fever. These episodes are separated by symptom free intervals. No lesions will be formed. Hence, this option is incorrect.
(d) Leptospira interrogans :
It causes leptospirosis. It is a zoonotic infection. The bacterium travels all over the human body through the bloodstream. The mucus lining of the blood vessels get damaged. This results in pain and fever. This may lead to dysfunction of liver and kidney. Hence, this option is incorrect.
Hence, the correct option is (b) Borrelia burgdorferi. It causes an infection that is characterized by a red rash and flulike symptoms.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 12MC
The most common cause of bacterial gastroenteritis in the United States is Campylobacter jejuni.
(a) Vibrio parahaemolyticus :
It causes cholera like gastroenteritis. It is due to the intake of shellfish grown in contaminated water. Rarely, it is severe leading to death. It is not the common cause for gastroenteritis. Hence, this option is incorrect.
(b) Campylobacter jejuni :
It is the most common cause of bacterial gastroenteritis in the United States. The infection is zoonotic. Hence, this option is correct.
(c) Helicobacter pylori :
It causes gastritis and most peptic ulcers. It is not the common cause for gastroenteritis. Hence, this option is incorrect.
(d) Vibrio cholerae :
It causes cholera. This is one of the world’s more pernicious diseases. It does not cause gastroenteritis. Hence, this option is incorrect.
Hence, the correct option is (b) Campylobacter jejuni. The most common cause of bacterial gastroenteritis in United States is Campylobacter jejuni.

Microbiology with Diseases by Taxonomy Chapter 21 Answers 13MC
The disease that forms lesions called gummas is syphilis.
(a) Ornithosis:
This disease is caused by Chlamydophila psittaci. It is a disease of birds that can be transmitted to humans. It causes flu like symptoms. It does not form any lesion. Hence, this option is incorrect.
(b) Syphilis:
It is a sexually transmitted disease. It is caused by Treponema pallidum pallidum. It forms lesions in all stages of the disease. The lesions formed in the tertiary stage of syphilis are called as gummas. They are rubbery, painful and swollen lesions. These lesions occur in bones, nervous tissue or on the skin. Hence, this option is correct.
(c) Trachoma:
It is an eye disease. It is caused by Chlamydia trachomatis. It does not form any lesions. Hence, this option is incorrect.
(d) Pneumonia:
The symptoms for pneumonia are cough, fever, fast breathing, fast heartbeat, nausea, pains and so on. But it does not form any lesions. Hence, this option is incorrect.
Hence, the correct option is (b) syphilis. The disease that causes gummas is syphilis.