NURS 223 PrepU:Chapter 12:Mechanisms of Infectious Disease

A client tells the health care provider he has heard several myths about viruses. The most appropriate information for the nurse to provide would be: a) "Viruses can produce symptoms of disease months to years later." b) "Viruses do not require a host cell to replicate." c) "Viruses are capable of replicating outside of a living cell." d) "Viruses kill cells they come in contact with immediately."

a) "Viruses can produce symptoms of disease months to years later." Viruses can produce symptoms of disease month to years later. Some viruses, such as hepatitis C, can remain latent for long periods of time without causing disease until months to years later. Viruses are incapable of replicating outside of a living cell and are incapable of replication unless in a host cell. Not every virus causes lysis and death of the host cell during replication.

Which of the following individuals is experiencing a health problem that is the result of a parasite? a) A man who acquired malaria while on a tropical vacation b) A college student who contracted Chlamydia trachomatis during an unprotected sexual encounter c) A woman who developed hepatitis A from eating at an unhygienic restaurant d) A hospital client who has developed postoperative pneumonia

a) A man who acquired malaria while on a tropical vacation Malaria is caused by a parasite. Chlamydial infections are bacterial, whereas hepatitis is viral. Pneumonia may be either viral or bacterial.

A nursing instructor is explaining how a pathogenic microorganism can invade the human body. The instructor knows that the students understand this process when they correctly identify which of the following ways the site of an infectious disease is determined? Select all that apply. a) By the type of pathogen b) By the number of pathogens c) By the portal of entry d) By the age of the person e) By the competence of the host's immunologic defense system

a) By the type of pathogen c) By the portal of entry e) By the competence of the host's immunologic defense system The type of pathogen, the portal of entry, and the competence of the host's immunologic defense system ultimately determine the site of an infectious disease.

Which most accurately describes the characteristics of saprophytes? They: a) Derive energy from decaying organic matter b) Are capable of spore production c) Are beneficial components of human microflora d) Have RNA or DNA, but never both

a) Derive energy from decaying organic matter Saprophytes are free-living organisms obtaining their growth from dead or decaying organic material in the environment. They are not necessarily spore producing, and they are not typical components of human microflora. Because most are bacterial or fungal, they contain both RNA and DNA

A public health nurse notes an increase in regional throat cancer cases. Upon epidemiological studies, many of the throat cancer clients also had oral exposure to human papillomavirus (HPV). This exposure to HPV would be considered by: a) Direct contact with infected secretions b) Deep penetration of open lesions c) Ingestion of HPV through the GI tract d) Accidental aspiration and inhalation of pathogens

a) Direct contact with infected secretions Most STIs are spread by direct contact. In addition to causing infectious diseases, certain viruses also have the ability to transform normal host cells into malignant cells during the replication cycle. This group of viruses is referred to as oncogenic and includes certain retroviruses and DNA viruses, such as the Epstein-Barr virus, hepatitis B virus, and human papillomavirus. Vertical transmission is possible for many sexually transmitted pathogens, but direct contact is more common. Ingestion and penetration are less likely mechanisms

A premature neonate in the ICU suspected of having an infection has blood drawn for class specific antibodies. Which of the following confirms that the neonate has developed a congenital infection? a) IgM antibodies are elevated. b) IgG titer is decreased. c) Initial IgM-specific antibodies are negative. d) IgG antibodies remain elevated throughout entire ICU admission.

a) IgM antibodies are elevated. Serology samples are used to identify infectious organisms by measuring the levels of antibodies. The measurement of antibody titers has another advantage in that specific antibody types such as IgM and IgG are produced by the host during different phases of an infectious process. IgM-specific antibodies generally rise and fall during the acute phase of the disease, whereas the synthesis of the IgG class of antibodies increases during the acute phase and remains elevated until or beyond resolution. Measurements of class-specific antibodies are also useful in the diagnosis of congenital infections. IgM antibodies do not cross the placenta, but certain IgG antibodies are transferred passively from mother to child during the final trimester of gestation. Consequently, an elevated level of pathogen-specific IgM antibodies in the serum of a neonate must have originated from the child and therefore indicates congenital infection. A similarly increased IgG titer in the neonate does not differentiate congenital from maternal infection

A client has begun taking acyclovir, an antiviral medication, to control herpes simplex outbreaks. What is this drug's mechanism of action? a) Interference with viral replication processes b) Antagonism of somatic cell binding sites c) Inhibition of viral adhesion to cells d) Elimination of exotoxin production

a) Interference with viral replication processes Acyclovir, like most antiviral drugs, interferes with normal viral replication. Antiviral drugs do not normally affect adhesion, and viruses are not associated with the production of exotoxins.

A teenage male develops a severe case of "athlete's foot." He asks, "How did I get this?" The health care worker explains that certain fungi become infectious (called dermatophytes) and exhibit which of the following characteristics? a) Limited to cooler cutaneous surfaces b) Like a moist environment c) Need higher blood flow to survive d) Prefer to grow in warm environments like shoes/socks

a) Limited to cooler cutaneous surfaces Dermatophytes are not able to grow at core body temperature, preferring the cooler surface skin areas instead of moist skin folds. Diseases caused by these organisms, including ringworm, athlete's foot, and jock itch, are collectively called superficial mycoses.

A client newly diagnosed with the neurodegenerative disease Creutzfeldt-Jakob disease (CJD) asks why antibiotics are not part of the treatment plan. How should the nurse respond? a) Prions are not affected by antibiotics. b) Antifungals are needed to kill CJD. c) Anaerobic parasites are destroyed by oxygen. d) CJD is only susceptible to antiretrovirals.

a) Prions are not affected by antibiotics. Transmissible neurodegenerative diseases such as kuru, Creutzfeldt-Jakob disease, and bovine spongiform encephalopathy (BSE) in cows are caused by prions. Prions are proteins that do not contain genetic material, but are believed to replicate by binding to the cell surface and using cellular materials. Because prions are very stable and lack nuclear material or metabolic processes they are not vulnerable to any current antimicrobial therapy

Select the statement that best describes the major difference between prokaryotes and eukaryotes. a) Prokaryotes lack an organized nucleus. b) Only prokaryotes contain DNA and RNA. c) Prokaryotes are composed of organized intracellular organelles. d) Eukaryotes lack an organized nucleus.

a) Prokaryotes lack an organized nucleus. Bacteria are autonomously replicating unicellular organisms known as prokaryotes because they lack an organized nucleus. Compared with nucleated eukaryotic cells, the bacterial cell is small and structurally primitive. Similar to eukaryotic cells but unlike viruses, bacteria contain both DNA and RNA, although their genome is considerably smaller than eukaryotes and typically is encoded on a single chromosome.

An HIV-positive mother passes the virus to her infant during delivery. This type of transmission is known as: a) Vertical transmission b) Horizontal transmission c) Vesicle transmission d) Heterozygous transmission

a) Vertical transmission The transmission of STIs is not limited to sexual contact. Vertical transmission of these agents, from the mother to child, can occur across the placenta or during birth when the mucous membranes of the child come in contact with infected vaginal secretions of the mother. The other options are not modes of transmission.

Global infectious diseases are now being recognized. These diseases, known as endemic to one part of the world, are now being found in other parts of the world because of international travel and a global marketplace. Which of the following is considered a global infectious disease? a) West Nile virus b) Coxsackie disease c) Respiratory syncytial disease d) Hand, foot, and mouth disease

a) West Nile virus Aided by a global market and the ease of international travel, the past 5 years has witnessed the importation or emergence of a host of novel infectious diseases. During the late summer and early fall of 1999, West Nile virus (WNV) was identified as the cause of an epidemic involving 56 clients in the New York City area. This outbreak, which led to seven deaths (primarily in the elderly), marked the first time that WNV had been recognized in the Western hemisphere since its discovery in Uganda nearly 60 years earlier. Coxsackie diseases, caused by the coxsackie virus; respiratory syncytial disease, better known as RSV; and hand, foot, and mouth disease are not considered global diseases.

A nurse is teaching parents of a child with scarlet fever. Which of the following statements indicates that the parents understand the treatment for the child? a) "Scarlet fever is a gram-negative bacteria that requires no antibiotics to treat." b) "I will give the antibiotic for the full 10 days." c) "My daughter cannot go to school while she is taking antibiotics." d) "I will apply antibiotics as a cream to her rash twice a day."

b) "I will give the antibiotic for the full 10 days." Streptococcus pyogenes, the agent of scarlet fever, is a gram-positive streptococcal organism. It is spherical, grows in chains, and stains purple by Gram stain. Not all antibiotics are effective against all pathogenic bacteria. Some agents are effective only against gram-negative bacteria, and others are specific for gram-positive organisms. The so-called broad-spectrum antibiotics, such as the newest class of cephalosporins, are active against a wide variety of gram-positive and gram-negative bacteria.

Sometimes the host's white blood cells are unable to eliminate the microorganism, but the body is able to contain the dissemination of the pathogen. What is this called? a) Lesion b) Abscess c) Acne d) Pimple

b) Abscess An abscess is a localized pocket of infection composed of devitalized tissue, microorganisms, and the host's phagocytic white blood cells: in essence, a stalemate in the infectious process. A pimple is a small papule or pustule. A lesion is a pathologic change in body tissue. Acne is a disease of the skin

Canada's Centre for Emergency Preparedness and Response is vigilantly keeping watch for terrorist events involving biologic agents. Of those on the list, which is of highest concern? a) AIDS b) Anthrax c) Parvovirus d) Prion diseases

b) Anthrax Anthrax is an ancient disease caused by the cutaneous inoculation, inhalation, or ingestion of the spores of Bacillus anthracis. Due to the ease of transmission and the speed of infection, it is of greatest concern. Parvovirus only infects canines. AIDS is not easily spread (via fluids and open wounds), and prion disease spreads through the consumption of brain material.

A client is suspected of having a parasitic infection with roundworms. For what laboratory testing will the nurse prepare the client to most rapidly identify this infection? a) Antibody titer b) Stool exam for ova c) Gene sequencing d) Cell culture

b) Stool exam for ova Cultures of microorganisms are commonly used to grow bacteria, fungi, and yeasts. Some protozoa and helminths can be cultured; however, the fastest and most common method for identifying parasitic worms is visible identification of the organisms, cysts, or ova from a client specimen. Cell cultures are grown on a specific type of media used for Chlamydiaceae, Rickettsiaceae, and human viruses. Antibody titers are useful for indirectly diagnosing diseases that cannot be cultured, such as hepatitis B. Gene sequencing is commonly used for identifying viruses such as HIV and hepatitis C.

Although growth rate is variable among types of bacteria, the growth of bacteria is dependent on: a) Individual cell motility b) Biofilm communication c) Availability of nutrients d) An intact protein capsid

c) Availability of nutrients Bacterial growth is dependent upon the availability of nutrients and physical growth conditions. Bacteria prefer to colonize as biofilm and communicate with other bacteria within the biofilm, but biofilm is not necessary for growth. Viruses (not bacteria) form a capsid. Although some bacteria have projections for motility, these are not necessary for growth.

Sexually transmitted infections (STIs) are typically spread by which of the following mechanisms? a) Penetration b) Ingestion c) Direct contact d) Vertical transmission

c) Direct contact Most STIs are spread by direct contact. Vertical transmission is possible for many sexually transmitted pathogens, but direct contact is more common. Ingestion and penetration are less likely mechanisms.

Which of the following would be considered an example of transmitting an infection from person-to-person through shared inanimate objects (fomites)? a) Malaria from mosquito bites b) Tuberculosis from inhalation of air after a cough c) HIV from a contaminated IV drug user needle d) Typhoid fever from traveling to a third-world country

c) HIV from a contaminated IV drug user needle Infections can be transmitted from person-to-person through shared inanimate objects (fomites) contaminated with infected body fluids. An example of this mechanism of transmission would include the spread of the HIV and hepatitis B virus through the use of shared syringes by intravenous drug users. Infection can also be spread through a complex combination of source, portal of entry, and vector. Infection with hantavirus pulmonary syndrome is a prime example. This viral illness is transmitted from mice to humans by inhalation of dust contaminated with saliva, feces, and urine of infected rodents.

There has been an incidence of influenza in both Europe and in the United States. What is the term that best describes this incidence? a) Epidemic b) Outbreak c) Pandemic d) Endemic

c) Pandemic A pandemic incidence refers to the spread of disease beyond continental boundaries, while an epidemic describes an abrupt and unexpected increase in the incidence of disease over endemic rates.

Which client best describes an example of infection originating with a fomite? a) 22-year-old woman who contracts Lyme disease after a tick bite. b) 44-year-old man who has trichinosis after eating undercooked pork. c) 44-year-old nurse who tests positive for tuberculosis (TB) after admitting a TB-positive client. d) 32-year-old man who contracts hepatitis B by sharing a syringe.

d) 32-year-old man who contracts hepatitis B by sharing a syringe. An object that carries an infectious organism, such as a dirty syringe, is known as a fomite. Airborne contact with TB does not utilize a fomite, and infection by way of contact with an infected arthropod constitutes zoonosis. Consuming ova in meat would constitute infection by ingestion.

A client has been diagnosed with an abscess. Upon assessment of the client, the nurse would expect to find: a) A circular pigmented area with a bull's-eye b) Several raised, reddened nodules containing sanguineous fluid c) White patchy areas on the anterior surface d) A localized pocket of infection composed of devitalized tissue, microorganisms, and the host's phagocytic white blood cells

d) A localized pocket of infection composed of devitalized tissue, microorganisms, and the host's phagocytic white blood cells An abscess is a localized pocket of infection composed of devitalized tissue, microorganisms, and the host's phagocytic white blood cells: in essence, a stalemate in the infectious process. In this case, the dissemination of the pathogen has been contained by the host, but white cell function within the toxic environment of the abscess is hampered, and the elimination of microorganisms is inhibited. The other options do not describe an abscess

Which agent is considered to be high-risk in a bioterrorism event? a) M. tuberculosis b) E. coli c) Hantavirus d) B. anthracis

d) B. anthracis Of this listing of potential bioterrorism agents, Bacillus anthracis falls into category A as a high-risk agent. The other options are all viable threats but fall into a lower category of risk.

Sputum samples from a client with pneumonia contain an infective agent that has a peptidoglycan cell wall, expresses endotoxins, replicates readily in broth and on agar, grows in clusters, has pili, and does not stain when exposed to crystal violet. This client's pneumonia has what etiology? a) Mycoplasmal b) Chlamydial c) Viral d) Bacterial

d) Bacterial Although chlamydiae, viruses, and mycoplasmas all can cause pneumonia, only bacteria have all of these characteristics. Chlamydiae and viruses are obligate intracellular organisms and therefore would grow only in cell culture, and mycoplasmas lack the peptidoglycan cell wall typical of bacteria.

Which one of the following relates to bacterial shape? a) Gram-negative b) Anaerobic c) Prion d) Cocci

d) Cocci The structure and synthesis of the cell wall determine the microscopic shape of the bacterium (e.g., spherical [cocci], helical [spirilla], or elongate [bacilli]).

Which one of the following organisms causes peptic ulcers? a) Salmonella typhimurium b) Escherichia coli c) Staphylococcus aureus d) Helicobacter pylori

d) Helicobacter pylori The bacterium Helicobacter pylori is an extreme example of a site-specific pathogen. Helicobacter pylori is a significant cause of gastric ulcers.

A client attending a health fair asks how anthrax will be treated in the event of a bioterrorism attack. How should the nurse respond? a) If you have anthrax, you will need infusion of antitoxins. b) Everyone should have an emergency supply of antibiotics to take in case of an attack. c) Anthrax is a virus that spreads by spores that can be inactivated with disinfectants. d) Individuals who are exposed will be isolated and given antibiotics.

d) Individuals who are exposed will be isolated and given antibiotics. Potential agents to be used in a bioterrorism attack include the bacillus that causes anthrax. Anthrax spreads by spores found in infected secretions, soil, or animal products. This microbe is susceptible to antibiotic treatment. Disinfecting the area will not treat the infected individual.

A fomite is which one of the following? a) Natural antibiotic b) Natural disinfectant c) Tick-like ectoparasite d) Infection transfer agent

d) Infection transfer agent Inanimate objects that carry an infectious agent are known as fomites.

A client has developed an infection from an exogenous source. The nurse recognizes this as acquired from: a) The host's own microbial flora, as would be the case in an opportunistic infection b) An inherited trait from the maternal side of the family c) The host ingesting excessive multivitamins d) Sources in the external environment, such as the water, food, soil, or air

d) Sources in the external environment, such as the water, food, soil, or air Exogenous infections are acquired from sources in the external environment, such as the water, food, soil, or air. Endogenous infections are acquired from the host's own microbial flora, as would be the case in an opportunistic infection. The source of the infectious agent can also be another human being, as from mother to child during gestation (congenital infections); an inanimate object; an animal; or a biting arthropod. Vitamins or inheritance will not contribute to infection.

Infections that are passed from animals to humans are known as: a) Perinatal b) Opportunistic c) Nosocomial d) Zoonotic

d) Zoonotic Zoonotic transmission of a disease is that from an animal to a human. Perinatal infections are passed from the mother to the infant. Opportunistic infections occur when the victim is in a compromised state. Nosocomial infections are acquired in hospital settings