Infection Control Today - 06/2002: Who wants to be a Microbiologist?

June 1, 2002

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Who wants to be a Microbiologist?
Comical Clues to Cleaning and Disinfecting

By Kelli M. Donley

He sits across from you in the gray suit, with the perfectly matching gray
tie. While he berates you with questions, the only thing you can concentrate on
is your increased heart rate and perspiring brow. The room grows dark,
spotlights circle, nerve-wracking music plays and you silently review your
lifelines. No, that monochromatic gentleman isn't Regis Philbin -- he's your
infection control practitioner (ICP). [Audience gasp!]

Don't be intimidated about cleaning and disinfecting. Be prepared to answer a
bombardment of infection control-related questions.

Reviewing the Basics

What is the definition of a microbe?

A. A small robe.
B. A unicellular organism.
C. An ultramicroscopic unit of protoplasm.
D. An antifungal agent.


What is the definition of a bacterium?
A. A one-celled organism without a true nucleus.
B. A tumor-like growth.
C. A parasite that invades red blood cells.
D. A ring-like thickening of tissue.


Categories of antimicrobials include all but one of the following:
A. Spongiforms
B. Disinfectants
C. Antiseptics
D. Germicides


Viruses have all but one of the following characteristics:
A. They are the smallest organism identified by an electron microscope.
B. They have a core of either DNA or RNA.
C. They reproduce outside of cells.
D. They adhere to cell membranes to avoid destruction by the immune system.


The clustering shape of bacteria is called?
A. Micrococci
B. Diplococci
C. Streptococci
D. Staphylococci


What does the suffix stasis mean?1
Example: bacteriostasis
A. The study of matter at rest.
B. Infectious.
C. The inhibition of microbial growth by means other than killing.
D. Remaining in a fixed condition.


Hans C.J. Gram, a Danish physician, created a method of staining bacteria to:
A. Identify certain microorganisms.
B. Determine their lifespan.
C. Determine their protein makeup.
D. Identify the number of bacteria present.


The difference between disinfection and sterilization is:
A. Sterilization kills all organisms present.
B. An object can be partly sterilized.
C. Tissue cannot be disinfected.
D. Disinfectants kill only viruses.


Antiseptics are used to clean:
A. Hospital surfaces
B. Intravascular medical instruments
C. Live tissue
D. Implantable devices


Disinfectants work better under all but one of the following conditions:
A. When there are no endospores.
B. When cells are actively growing.
C. Against gram-negative bacteria.
D. On surfaces.


All but one of the following are methods of sterilization:
A. Moist heat
B. HEPA filtration
C. Dry heat
D. UV radiation


Enzymes have all but one of the following characteristics:
A. They cannot act outside of cells or live in vitro.
B. They are made of proteins.
C. They can catalyze numerous times.
D. They do not need an external energy source to react.


A bacteriophage is a:
A. A virus that infects bacteria.
B. A substance that inhibits the growth of bacteria.
C. A buildup of proteins within bacteria.
D. The condition of having bacteria in the urine.


If left on a stainless steel table for one month, which organism would die
the fastest?1
A. E. coli suspended in a drop of water.
B. E. coli suspended in pus.
C. An endospore
D. Mycobacterium tuberculosis

Need a Lifeline?

By Kelli M. Donley

polling your staffing audience for the right answer may help bring you down to
the 50/50 mark, it is important to know when to call in the experts for
additional help. Once such microbiology whiz is Stephen T. Abedon, PhD,
professor and researcher at Ohio State University. Abedon, who created several
of the aforementioned test questions for one of his course lectures, is a
microbial evolutionary ecologist who runs a quirky Web site about his passion:
phages. (

"The Web site represents a quasi-organized list of everything that I
wish I knew off the top of my head, but don't," he says.

Abedon, who teaches medical microbiology, explains several principles
healthcare workers (HCWs) should know about cleaning and disinfecting.

"To kill, a disinfectant must both penetrate and then destroy some
aspect of a microorganism," he says. "It is easy to produce highly
penetrating and deadly disinfectants. The problem, however, is one of handling
those disinfectants. For instance, nuclear weapons probably do a wonderful job
of killing off local microbial life, but hardly would qualify as a relatively
innocuous disinfection procedure.

"Mycobacterium tuberculosis is resistant to disinfectants
particularly because the waxy outer coating of mycobacteria prevents the
penetration of various chemical antibacterials. The extra-slow growth rates of
these bacteria may also give rise to their reduced susceptibility since
disinfectants typically are more effective against actively growing bacteria
than against not-growing bacteria. So, disinfectants tend to lack an ability to
destroy everything (including all living things) in their vicinity, which is
good because we often are in their vicinity, but also is bad because it limits
their ability to kill the very organisms that you would hope they would

And the details surrounding that million-dollar question?

"Endospores are notoriously resistant to desiccation (drying out), as
are mycobacteria," he says. "So in the question that leaves the E.
It turns out that bacteria can be more stable suspended within
organic-rich environments, such as pus. Note, however, that it once was a
perfectly legitimate means of storage of at least some bacterial strains to
simply place them in distilled water and then hold them there at room

Abedon, who has a penchant for all things tie-died, has comical, yet
practical advice for those cleaning and disinfecting medical instruments.

"Wear gloves to protect yourself, keep your hands away from your face
and also avoid using chemical disinfectants except in reasonably well-ventilated
environments," he says. "In other words, take care of yourselves. Oh
yes, and don't forget to read the directions on the disinfectant bottle."

And yes, that is his final answer.