Wet 111 Microbiological Contaminants Moodle Quiz

How much sodium hypochlorite, in gallons, is required to obtain a residual of 100 mg/L in a well? The casing diameter is 18 inches and the length of water filled casing is 80 feet. Sodium hypochlorite contains 5.25% available chlorine. Assume a demand of 15 mg/L.

2.3 gallons

The Multiple Tube Fermentation Technique (which results in a Most Probable Number or (MPN)) involves adding the water sample to a set of tubes, each of which contains either lactose broth or lauryl tryptose broth and an inverted tube. The tubes are then incubated at 35 ± 0.5º C for 24 to 48 hours (fecal coliforms are incubated in a water bath at 44.5 ± 0.2º C). If gas production is observed in an inverted tube after incubation, the sample contains total coliforms. T or F?

TRue

The Presence/Absence (P/A) method is a qualitative test that indicates only the presence or absence or organisms, not the number of organisms. In the Presence/Absence Coliform Test, 100 mL of the water sample is added to a bottle containing P/A Broth, and incubated at 35 ± 0.5º C for 24 to 48 hours. If the broth becomes yellow-colored, total coliforms are present. T or F?

TRue

What are all of the qualities of an ideal indicator organism?

a. Easy to analyze for. b. Directly associated with target or pathogenic organism. c. Present in greater numbers. d. Not ubiquitous. e. More difficult to kill than target organism.

The TCR requires systems to monitor for total coliforms at a frequency proportional to the number of people served. If any sample tests positive for total coliforms, the system must perform the following additional tests:

*Further test that culture for the presence of either fecal coliforms or Escherichia coli; *Take one set of 3-4 repeat samples at sites located within 5 or fewer sampling sites adjacent to the location of the routine positive sample within 24 hours; and *Take at least 5 routine samples the next month of operation

What is a commonly used indicator of possible health problems found in plants, soil, water and the intestines of humans and warm-blooded animals?

Coliform bacteria

Which of the following is true about viruses? a. Viruses are extremely complex molecules that typically contain a protein coat surrounding a DNA or RNA core of genetic material. b. They are very small 10-25 nm. c. VIRUSES ARE MORE RESISTANT TO CHLORINE THEN BACTERIA! d. All of the above Correct

D. All are correct Viruses depend on the host cells that they infect to reproduce. When found outside of host cells, viruses exist as a protein coat or capsid, sometimes enclosed within a membrane. The capsid encloses either DNA or RNA which codes for the virus elements. When it comes into contact with a host cell, a virus can insert its genetic material into its host, literally taking over the host's functions http://www.ucmp.berkeley.edu/alllife/virus.html. Which of the following is true about viruses?

The destruction of the larger portion of microorganisms with the probability that all pathogens are killed is called?

Disinfection

Total and fecal coliform are pathogenic?

False

Coliforms are used as indicator bacteria to verify the effectiveness of disinfection techniques because ______.

They are easier to detect and are harder to destroy than most pathogenic organisms

"Cryptosporidium infection (cryptosporidiosis) is a gastrointestinal disease whose primary symptom is diarrhea. The illness begins when the tiny cryptosporidium parasite enters your body and travels to your small intestine. Cryptosporidium then begins its life cycle inside your body — burrowing into the walls of your intestines and then later being shed in your feces T or F?

True

"Not all bacteria are harmful. In fact, less than 1 percent cause disease, and some bacteria that live in your body are actually good for you. T or F?

True

Approved tests for total coliform bacteria include the membrane filter, multiple tube fermentation (MTF), presence absence (PA), MPN and MMO-MUG ("Colilert") methods?

True

Because the parasite is protected by an outer shell, it can survive outside the body and in the environment for long periods of time (i.e., months) and is resistant to chlorination (A multiple barrier approach i.e., filtration removes cysts during the treatment process). T or F?

True

Coliform absence is a good bacteriological indicator of safe water? T or F

True

Coliform are more resistant to chlorination and ideally should have a longer life span than most pathogens?

True

Coliform bacteria are a natural part of the microbiology of the intestinal tract of warm blooded mammals, including man. Coliform bacteria can also be found in soil, other animals, insects?

True

Coliform bacteria are not pathogenic (disease causing) organisms, and are only mildly infectious. For this reason these bacteria are relatively safe to work with in the laboratory.

True

Cryptosporidium parvum, a single-celled animal, i.e., a protozoa, is an obligate intracellular parasite.Many species of Cryptosporidium exist that infect humans and a wide range of animals. The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it very resistant to chlorine disinfection T or F?

True

During the past two decades, Crypto has become recognized as one of the most common causes of waterborne illness in the United States . Infectious dose--Less than 10 organisms and, presumably, one organism can initiate an infection.

True

Each total coliform sample must be tested for the presence of fecal coliforms or E. coli. If any routine sample is total coliform-positive, repeat samples are required.

True

If a sample tests positive for coliforms, the system must collect a set of repeat samples within 24 hours. When a routine or repeat sample tests positive for total coliforms, it must also be analyzed for fecal coliforms and Escherichia coli (E. coli), which are a type of coliform bacteria that are directly associated with fresh feces. A positive result to this last test signifies an acute MCL violation, which necessitates rapid state and public notification because it represents a direct health risk. T or F?

True

In the Membrane Filter (MF) Technique, a vacuum pulls 100 mL of water sample through a membrane filter held in place by a filter-holding device. Total coliform and other bacteria are retained on the filter. The filter is then placed on a special medium which allows the growth of total coliform and incubated at 35 ± 0.5º C for 22 to 24 hours. If a total coliform-like colony is observed on the membrane, the lab should make sure that it is a total coliform by using another EPA approved test. T or F?

True

In the rule, EPA set the maximum contaminant health goal (MCLG) for total coliforms at zero. Since there have been waterborne disease outbreaks in which researchers have found very low levels of coliforms, any level indicates some health risk. Thus, EPA also set a legal limit on total coliforms. Systems must not find coliforms in more than five percent of the samples they take each month to meet EPA's standards. If more than five percent of the samples contain coliforms, water system operators must report this violation to the state and the public. T or F?

True

The MPN (most probable number) method uses a test tube full of media with a smaller inverted test tube inside which captures carbon dioxide gas released from the growth of coliform bacteria. A series of dilutions and replicates are set up, and those producing gas in 24 hrs at 35 degrees C are counted. A statistical analysis is used to determine the most probable number of bacteria cells present.

True

The Mixed Media ONPG-MUG (MMO-MUG) test is the simplest of the EPA approved tests for total coliforms. A 100 mL water sample is added to a flask containing the MMO-MUG powder, mixed, and incubated at 35 ± 0.5º C for 24 hours. The formation of a yellow color denotes the presence of total coliforms. T or F?

True

The Total Coliform Rule was published in 1989 and became effective in 1990. The rule set both health goals (MCLGs) and legal limits (MCLs) for the presence of total coliform in drinking water. The rule also detailed the type and frequency of testing that water systems must undertake. T or F?

True

The city of Portland collects about 320 samples a month for BacT analysis.

True

The coliform group of bacteria comprise all the aerobic and faculative anaerobic gram negative, nonspore forming rod shaped bacteria that ferment lactose (a sugar) within 48 hours at 35º C. In general, coliform bacteria can be divided into a fecal and a non-fecal group. Fecal coliforms can grow at a higher temperature (45º C) than non-fecal coliforms. The EPA is evaluating four analytical methods for testing water in distribution systems to determine whether total coliforms are present. These are the Membrane Filter Technique, Multiple-Tube Fermentation Technique, Presence-Absence Coliform Test, and the Mixed Media ONPG-MUG test. T or F?

True

The membrane filter method uses a fine porosity filter which can retain bacteria. The filter is placed in a petri (culture) dish on a pad with growth enrichment media (mEndo) and is incubated for 24 hrs at 35 degrees C. Individual bacteria cells which collect on the filter grow into dome-shaped colonies. The coliform bacteria have a gold-green sheen, and are counted directly from the dish. Since some other bacteria may develop a similar color, a confirmation test using more specific media is required. The confirmation procedure requires an additional 24 to 48 hrs to complete the test for suspected positive total coliform tests. T or F?

True

The number of coliform samples a system must take depends on the number of customers that it serves. Systems which serve fewer than 1000 people may test once a month or less frequently, while systems with 50,200 customers test 60 times per month and those with 2.5 million customers test at least 420 times per month. T or F?

True

The total coliform group is relatively easy to culture in the lab, and therefore, has been selected as the primary indicator bacteria for the presence of disease causing organisms?

True

The total coliform rule applies to all public water systems.

True

The total coliform rule was adopted on June 29, 1989?

True

Within 24 hours of learning a ROUTINE total coliform sample is positive at LEAST 3 REPEAT samples must be collected and analyzed for total coliforms.

True

You can use multiple tube fermentaion (MTF) to analyze and count total coliforms in a sample. A positive in the Presumptive test gets analyzed in the confirmed test for total coliforms by transferring the positive samples to brilliant green lactose. A positive is gas production. T or F?

True

Which of the following is true about Giardia lamblia (intestinalis)? a. It attaches itself to the upper intestinal tract and produces cysts which can be shed in feces b. It is easily killed by chlorine c. Cysts dies easily and cannot survive in adverse conditions d. Giardia are typically 10-25 nanometers in diameter

a. It attaches itself to the upper intestinal tract and produces cysts which can be shed in feces Correct Giardia lamblia (intestinalis) is a single celled animal, i.e., a protozoa, that moves with the aid of five flagella. It is the most frequent cause of non-bacterial diarrhea in North America. Organisms that appear identical to those that cause human illness have been isolated from domestic animals (dogs and cats) and wild animals (beavers and bears)--(see the OR connection?). The Infectious Dose - Ingestion of one or more cysts may cause disease, as contrasted to most bacterial illnesses where hundreds to thousands of organisms must be consumed to produce illness.

Coliform bacteria are: a. More resistant to chlorination than pathogenic bacteria b. Less resistant to chlorination than pathogenic bacteria c. A group of pathogens causing hepatitis d. A group of pathogens causing cholera

a. More resistant to chlorination than pathogenic bacteria

Which of the following is true about cryptosporidium? a. it is easily killed by chlorine b. It causes 7-14 days of diarrhea, a low grade fever, nausea, and abdominal cramps. c. Antiobiotics are always given as treatment for cryptospordiosis

b. It causes 7-14 days of diarrhea, a low grade fever, nausea, and abdominal cramps.

What are the three major groups of disease causing (pathogenic) microorganisms in drinking water? a. Bacteria b. Viruses c. Protozoa d. All of the above

d. All are Correct These three groups are probably the greatest remaining health risk management challenge for drinking water supplies. rember lecture one where the most violations in our nations drinking water were from microbial contamination.

Mary Mallon was the first identified carrier of Typhoid Fever. Salmonella typhi is the bacteria responsible for the life-threatening illness known as typhoid fever. In the United States about 400 cases occur each year, and 75% of these are acquired while traveling internationally. Typhoid fever is still common in the developing world, where it affects about 21.5 million persons each year. Which of the following is true about bacteria? a. contain DNA b. definitive cell wall c. 0.1 to 1 micrometer d. All of the above

d. All the below are true a. contain DNA b. definitive cell wall c. 0.1 to 1 micrometer Can you blame her. She was asymptomatic.

Which of the following is/are true about bacteria? a. Are a single celled organisms with a cell wall and contain DNA (not in the nucleaus). b. They multiple by binary fission c.They have no well defined nucleus and can be rod, spherical, or spiral in shape d. All of the above

d. all are correct Bacteria fall into a category of life called the Prokaryotes (pro-carry-oats). Prokaryotes' genetic material, or DNA, is not enclosed in a cellular compartment called the nucleus.

Which of the following is true about protozoa? a. They have a true nucleas b. They do not have a cell wall c. They reproduce by binary fission and eat bacteria d. All of the above

d. all are correct The name protozoa means "first animals." As the principal hunters and grazers of the microbial world, protozoa play a key role in maintaining the balance of bacterial, algal, and other microbial life. They are extremely important in wastewater treatment and they are also an important food source for larger creatures in the food chain

Which of the following is/are true about total coliforms? a. always be present in contaminated water b. always be absent when fecal contamination is not present c. generally survive longer in water then pathogens d. easy to identify and safe to the person doing the analysis e. all of the above

e. all are true Since most pathogens in drinking waters, if detected, are usually in very low concentrations, it would be difficult and ineffective to test water for evey single pathogen that could occur withiin it. For this reason, coliforms were selected to be indicator organisms. They are always present in water contaminated with fecal material, are easy to detect, are generally more hardy than true pathogens, and will be found in greater numbers in contaminated water.