bacterial infection IS

The collection of microorganisms (bacteria, viruses, fungi) existing on the human body is referred to as _.

Human microbiome

The bacterial populations in the human microbiome are _.

Not homogeneous, varying in composition and numbers depending on body area

Microbial populations on the body outnumber human cells by a ratio of _.

10:1

The weight of the microbial population in the human microbiome may account for _.

2 to 6 pounds of an individual’s body weight

More than ____% of the bacteria that comprise the human microbiome cannot be cultured in vitro.

90%

The process by which a microorganism establishes itself and leads to host injury is called _.

Infection

An infection without clinical signs or symptoms is called _.

Subclinical infection

The microorganisms that establish long-term relationships with the host without causing harm are known as _.

Commensal organisms

Commensal organisms can live on or in the host without causing harm, such as _.

Staphylococcus epidermidis

A relationship in which both organisms benefit is called _.

Mutualistic relationship

An example of a mutualistic bacterium is _.

Lactobacillus species in the vaginal canal

A parasitic relationship occurs when _.

One organism benefits at the expense of the host

An example of a parasitic microorganism is _.

Chlamydia trachomatis

The establishment of an organism that leads to host injury is referred to as _.

Infection

Pathogenicity refers to _.

The inherent ability of an organism to cause disease

Virulence refers to _.

The extent of damage or pathology caused by the organism

Infectivity refers to _.

The ability of an organism to establish an infection in a host

The term "contagious" is used to describe an organism with _.

High infectivity

The three types of symbiotic relationships between humans and bacteria are _.

Commensalistic, mutualistic, parasitic

Commensalistic bacteria are those that _.

Live on or in the host without causing harm or benefit

An example of a commensalistic organism is _.

Staphylococcus epidermidis

In a mutualistic relationship, both organisms _.

Benefit from the interaction

An example of mutualistic bacteria in humans is _.

Lactobacillus species in the vaginal canal

In a parasitic relationship, _.

One organism benefits while harming the host

An example of a parasitic organism is _.

Chlamydia trachomatis

Pathogenicity refers to the ability of an organism to _.

Cause disease

Virulence refers to the _.

Degree of damage or pathology caused by an organism

The capacity of an organism to spread from one host to another is called _.

Infectivity

Opportunistic pathogens can cause disease in hosts with _.

Compromised immune systems

A microorganism that is capable of causing harm to the host is called _.

Pathogen

A microorganism that can be harmful only in certain conditions is referred to as _.

Opportunistic pathogen

Bacterial properties or features that determine an organism's ability to cause disease are called _.

Virulence factors

Genetic determinants responsible for the production of virulence factors are usually located on _.

The bacterial chromosome or plasmids

Plasmids are _.

Self-replicating extrachromosomal DNA molecules

Plasmids can transfer virulence factors between bacteria through _.

Horizontal gene transfer

Structural features of bacteria involved in virulence include _.

Pili, capsule, and cell wall components

Pili are hair-like structures on bacteria that help with _.

Adherence to host tissues and resistance to phagocytosis

Pili may also play a role in _.

Genetic material exchange between bacteria (e.g., F pili or sex pili)

An example of bacteria with pili that resist phagocytosis is _.

Neisseria gonorrhoeae

A capsule is a _.

Polysaccharide layer surrounding the bacterial cell wall

The capsule of S. pneumoniae prevents _.

Phagocytosis by alveolar macrophages

An important feature of capsules is their ability to _.

Block phagocytosis, inhibit complement activation, and act as decoys for antibodies

Structural virulence features also help bacteria in _.

Adherence to host tissue, immune evasion, and survival in the host

The M protein of Streptococcus pyogenes is important for _.

Inhibiting phagocytosis and binding to host cells

The F protein of Streptococcus pyogenes helps with _.

Attachment to host cells

The M protein limits deposition of _ on the bacterial surface.

Complement component C3

The hyaluronic acid capsule of S. pyogenes helps with _.

Evasion of phagocytosis and immune system recognition

The first line of defense against bacterial infection includes _.

Intact skin and mucosal surfaces

Antimicrobial defense peptides (ADPs), such as defensins, are produced by _.

Epithelial cells and other immune cells

Lysozyme is an enzyme that specifically destroys _.

Peptidoglycan in the cell walls of bacteria, especially gram-positive bacteria

Defensins are classified into three types: _.

Alpha, beta, and theta

Alpha defensins are produced by _.

Neutrophils, certain macrophage populations, and Paneth cells

Beta defensins are produced by _.

Neutrophils and epithelial cells lining various organs

Theta defensins are produced by _.

Not found in humans

Complement proteins help in the immune defense by _.

Promoting chemotaxis and aiding in the lysis of bacteria

Cytokines like interleukins and tumor necrosis factor (TNF) are involved in _.

Regulating immune responses and inflammatory reactions

Acute-phase reactants, like C-reactive protein (CRP), are involved in _.

Activating the complement system and promoting phagocytosis

Phagocytosis is performed by immune cells such as _.

Neutrophils and macrophages

Pattern recognition receptors (PRRs) on innate immune cells recognize _.

Pathogen-associated molecular patterns (PAMPs)

The engagement of PRRs with PAMPs leads to the release of _.

Cytokines, chemokines, defensins, and other immune mediators

The primary defense against extracellular bacteria is _.

Humoral immunity, involving the production of antibodies

Cell-mediated immunity is crucial for attacking _.

Intracellular bacteria, such as Mycobacterium tuberculosis

Cytotoxic T cells play a role in _.

Directly attacking infected cells and controlling intracellular bacteria

The adaptive immune response includes both _.

Humoral immunity (antibodies) and cell-mediated immunity (T cells)

Some bacteria evade the immune system by altering their antigens through _.

Antigenic variation

Bacteria can also evade phagocytosis by producing _.

Capsules or surface proteins that inhibit immune cell recognition

An example of a bacteria that produces a capsule to evade phagocytosis is _.

Streptococcus pneumoniae

Some bacteria use proteases to degrade _.

Immunoglobulin A (IgA)

N. gonorrhoeae and H. influenzae are examples of bacteria that can _.

Cleave IgA, thereby evading mucosal immune defenses

One major strategy of immune evasion involves _.

Inhibiting chemotaxis, preventing the immune cells from reaching the infection site

The M protein of S. pyogenes interferes with _.

The adhesion of phagocytic cells to bacteria

Salmonella and M. tuberculosis resist digestion by phagocytes by _.

Preventing the fusion of lysosomes with phagosomes

The production of leukocidin by bacteria like S. aureus results in _.

The death of white blood cells (WBCs) through lysis

Some bacteria evade immune detection by _.

Downregulating MHC molecules on their surface

Streptococcus pyogenes produces Protein H to _.

Bind to C1 and prevent the activation of the complement cascade

Streptococci are gram-positive _.

Cocci

Streptococci are commonly arranged in _.

Pairs or chains

Streptococci are classified based on their ability to _.

Hemolyze red blood cells (RBCs)

Streptococci that completely lyse RBCs are classified as _.

β-hemolytic

Streptococci that partially lyse RBCs are classified as _.

α-hemolytic

Streptococci that do not lyse RBCs are classified as _.

γ-hemolytic

Group A streptococci (GAS) are identified by the presence of _.

A group-specific carbohydrate in their cell wall

Streptococcus pyogenes is also known as _.

Group A streptococcus (GAS)

The M protein of S. pyogenes is a key virulence factor that helps with _.

Inhibiting phagocytosis and facilitating adhesion to host cells

Streptococcus pyogenes may also have a capsule composed of _.

Hyaluronic acid

Serotyping of S. pyogenes is done by identifying _.

The M protein antigens

The M protein is highly variable, and there are ____ serotypes of it.

More than 80

Molecular techniques like PCR amplify the ____ gene to identify strains of S. pyogenes.

emm

Pulsed-field gel electrophoresis (PFGE) is used to _.

Obtain a DNA fingerprint for epidemiological studies of GAS

S. pyogenes produces various exotoxins, including _.

Pyrogenic exotoxins A, B, and C

Pyrogenic exotoxins in S. pyogenes cause _.

Scarlet fever

Streptolysin O is an exotoxin produced by S. pyogenes that _.

Lyses red blood cells

Deoxyribonuclease B (DNase B) produced by S. pyogenes contributes to its _.

Pathogenicity

Hyaluronidase produced by S. pyogenes contributes to its _.

Spread through tissues

Streptokinase produced by S. pyogenes helps with _.

Breaking down blood clots

The clinical manifestations of GAS infections include _.

Pharyngitis, impetigo, otitis media, and cellulitis

The primary skin infection caused by GAS is _.

Impetigo

Pharyngitis caused by GAS typically presents with _.

Fever, sore throat, tonsillar exudates, and cervical lymphadenopathy

Scarlet fever, caused by GAS, presents with a _.

Distinct rash and high fever

The most severe GAS infections can lead to _.

Necrotizing fasciitis and streptococcal toxic shock syndrome