Micro Final

What process is responsible for nitrogen fixation in legume nodules

Nitrogen Cycle

nitrogen fixation- is the conversion of atmospheric nitrogen gas into ammonia by nitrogen-fixing bacteria, primarily Rhizobium, within the root nodules of legumes.

cyanobacteria play a critical role in:

Cyanobacteria in oceans fix 50% of Earth's carbon

Cyanobacteria and phytoplankton
photosynthesize, supporting aquatic
food webs and producing ~50% of
global oxygen.

Explain how denitrification impacts nitrogen cycling in ecosystems

Denitrification:
• Nitrate → Nitrogen gas (N₂) by anaerobic denitrifiers
like Pseudomonas

harmful algal blooms contribute to the formation of “dead zones” explain why…

they deplete oxygen levels in water, leading to hypoxic conditions that cannot support most marine life.

Produce toxins that harm
fish, shellfish, and even
humans
• Potent muscle toxin
concentrated by shellfish
through filtration feeding

what are mycorrhizae, and how do they affect plants?

Mutualistic partnerships between plant roots and microbes such as
basidiomycetes, ascomycetes, or zygomycetes

• Plant feeds the fungus through photosynthesis
• Fungus helps anchor the plant and increase surface area for
capturing water and minerals

Microbes are essential in making foods like yogurt, cheese, and beer. What kinds of changes do they cause during production, and how do those changes affect the final product?

Microbes cause fermentation, converting sugars into acids, gases, and alcohols, which leads to flavor development, texture changes, and preservation of the final product.

Beer is produced through the controlled fermentation of barley sugars by
yeast.

Yeast strains are selected for specific flavor profiles.
• Contamination by wild yeasts or bacteria can spoil beer, though some styles (e.g., lambics)
rely on natural fermentation. This is beer fermenting at a brewery.
Wine is produced by fermenting grape juice (must) using yeast.

Yeast strains determine wine's alcohol content and aroma.
• Spoilage microbes (e.g., Brettanomyces) can introduce undesirable flavors but are valued in some
styles.
Wine grapes: The white film that covers
the grapes contains wild yeasts.
Saccharomyces cerevisiae

Cheese Production:
• Lactic acid bacteria (e.g., Lactobacillus, Streptococcus)
acidify milk, curdling proteins into cheese.
• Secondary microbes (e.g., Penicillium) develop flavors
in aged cheeses like Brie or Roquefort.
• Yogurt Production:
• Starter Cultures: Lactobacillus bulgaricus and
Streptococcus thermophilus ferment lactose into lactic
acid, thickening milk and giving it a tangy flavor.
• Sauerkraut and Kimchi:
• Fermentation of cabbage by natural lactic acid
bacteria (Leuconostoc, Lactobacillus) preserves the
food and enhances flavor.
• Kombucha:
• Fermentation of sweetened tea by a symbiotic culture
of bacteria and yeast (SCOBY) produces acids, ethanol,
and carbonation.

Explain the primary cause of antimicrobial resistance

Excessive use of antibiotics in agriculture promotes resistant bacterial strains.
• Resistant microbes spread between animals, humans, and the environment.
• Example: Escherichia coli resistant to colistin has been detected in food and water
systems.

explain the one health approach

Definition:
• One Health is an integrated, unifying approach that recognizes the
interconnectedness of human, animal, and environmental health.
• Core Principles of One Health:
• Shared Environments: Humans, animals, and microbes coexist in
interconnected ecosystems.
• Zoonotic Diseases: Over 60% of human infectious diseases (e.g.,
COVID-19, rabies) originate in animals.
• Environmental Health: Deforestation, climate change, and pollution
influence pathogen emergence.
• Role of Microbes in One Health:
• Beneficial microbes: Maintain gut health, prevent disease, and
degrade pollutants.
• Pathogenic microbes: Zoonotic and environmental pathogens
challenge health systems.

how might environmental changes, such as shifts in temp and habitat, affect where and how infectious disease spread?

Environmental changes can alter pathogen transmission dynamics, enhance vector habitats, and influence the distribution and virulence of infectious agents, leading to increased disease emergence in new areas.

which toxin is responsible for staphylococcal scalded skin syndrome?

•SSSS is an infection seen mainly in infants and young children, caused by exfoliative exotoxins produced by Staphylococcus aureus. These toxins lead to redness, tenderness, and peeling of the skin, resembling a burn.

•Symptoms include widespread redness, skin pain, and blistering.

•Toxins from S. aureus cause the outer layers of skin to separate and peel.

•Treatment often requires hospitalization and antibiotics.

define necrotizing fasciitis and name the organism often associated with it.

•Necrotizing fasciitis is a rare but serious infection often referred to as ‘flesh-eating disease.’ It spreads rapidly, causing tissue death that often requires surgical removal. Common causes include Streptococcus pyogenes and other bacteria that can break down connective tissue.

•Severe pain and swelling at the infection site.

•Rapid spread of infection through connective tissue.

•Requires surgical debridement and intravenous antibiotics.

what layer of the skin is most involved in cellulitis?

•Cellulitis: Redness, swelling, and warmth on the skin, usually around cuts.

•Cellulitis primarily involves the superficial layer, specifically the dermis and subcutaneous tissue, leading to inflammation.

Explain how monkeypox is primarily transmitted.

•Transmission: Zoonotic; direct contact with infected animals, human respiratory droplets, or contact with body fluids and lesion materials.

•Symptoms: Fever, lymphadenopathy (swollen lymph nodes), headache, muscle aches, and fatigue.

•Rash is similar to smallpox, beginning on the face and spreading to the body.

•Specific mpox vaccines available

•As of 2024, mpox cases in the US remain at low levels, with an average of about 59 cases reported weekly—a substantial decrease from the 2022 peak of over 3,200 weekly cases.

what organism is commonly associated with swimmers ear?

Swimmer's ear is commonly associated with Pseudomonas aeruginosa, a bacteria that thrives in moist environments.

Herpetic whitlow is a condition caused by HSV affecting which part of the body?

the fingers or nails

What condition is commonly caused by overgrowth of Malassezia yeast?

Dandruff or seborrheic dermatitis

which bacterium is primarily responsible for gas gangrene?

Clostridium perfringens, an anaerobic bacterium that produces toxins.

•Gas Gangrene (Clostridial Myonecrosis): Infection usually caused by Clostridium perfringens.

•Presents with severe pain, swelling, tissue necrosis, and foul-smelling discharge.

•Infected tissues may appear discolored, and gas bubbles can form in muscle and soft tissue.

•Rapidly progresses to systemic infection, potentially fatal if untreated.

what is a hallmark symptom of cutaneous anthrax?

•Caused by Bacillus anthracis, cutaneous anthrax is usually contracted through contact with infected animals or products (wool, hides, meat) and manifests as a black eschar.

•Spores enter the body through cuts or abrasions.

•The infection begins as a small bump that develops into an ulcer with a black center.

•If untreated, it can lead to septicemia, which is potentially fatal.

Treatment includes antibiotics such as penicillin, doxycycline, or ciprofloxacin

what are the different types of warts?

•Common Warts: Appear on hands, fingers; rough, raised surface.

•Plantar Warts: Found on feet; can grow inward due to pressure.

•Flat Warts: Small, smooth, often found on the face, hands, or legs.

•Filiform Warts: Long, thread-like, often around mouth or eyes.

what is molluscum contagious and how is it spread?

•Viral infection caused by the Molluscum contagiosum virus (MCV), a member of the poxvirus family

•Small, smooth, firm, dome-shaped nodules with a central dimple (umbilication).

•Often found on the face, neck, arms, and genital area.

•Common in: Children, immunocompromised individuals, and those with atopic dermatitis.

•Transmission: Spread through direct skin-to-skin contact, including sexual contact, or through contaminated objects (e.g., towels, clothing).

What is the stratum corneum?

•The stratum corneum, part of the epidermis, consists mainly of dead skin cells, providing a barrier.

•Epidermis: The outermost layer made of keratinized cells, which forms a waterproof barrier.

•Dermis: Located beneath the epidermis, contains connective tissue, blood vessels, hair follicles, and glands that support skin health and repair.

•Hypodermis: The deepest layer, made of adipose (fat) and connective tissue. Cushions the body and insulates against temperature changes.

what role does the normal skin microbiome play in regulating inflammation and supporting barrier integrity?

•The skin hosts a variety of commensal microorganisms, including bacteria, fungi, and viruses, which play roles in immunity and disease prevention.

•Common bacteria: Staphylococcus, Corynebacterium, and Propionibacterium (Cutibacterium)thrive in specific areas (moist, dry, or sebaceous).

•Skin fungi: Malassezia species are typically found in areas rich in sebaceous glands.

•Normal microbiota compete with pathogens for space and resources, producing substances that inhibit pathogen growth.

•The normal skin microbiome helps maintain homeostasis by regulating inflammatory responses and enhancing the skin barrier. This interaction is crucial for preventing overgrowth of pathogenic organisms and promoting skin health.

describe shingles.

•Reactivation of the Varicella-Zoster Virus (VZV), the same virus that causes chickenpox.

•Transmission occurs through direct contact with fluid from the shingles rash. Virus can spread to others who have not had chickenpox or the vaccine, potentially causing them to develop chickenpox, not shingles.

•Fluid-filled vesicles that follow a dermatomal pattern (along nerve pathways), typically restricted to one side of the body.

•Rash appears as clusters of blisters that can be intensely painful.

•Shingles vaccine (Shingrix) is recommended for adults over 50 to reduce the risk of shingles and its complications.

what pathogen causes hand, foot, and mouth disease, and what are the clinical manifestations of it?

•Causative Agents: Coxsackievirus A16, Enterovirus 71

•Transmission: Fecal-oral route, respiratory droplets, or contact with contaminated surfaces.

•Symptoms:

•Fever, sore throat, reduced appetite, and general malaise.

•Painful sores and red spots develop on hands, feet, and inside the mouth.

•Lesions are smaller and less extensive than chickenpox or smallpox

how worried should we be about small pox? why?

Smallpox is a highly contagious disease caused by the variola virus, which was eradicated in 1980. Due to its potential as a bioterrorism agent and the possibility of a resurgence, public health concerns remain.

•Transmission: Airborne droplets, direct contact with infected bodily fluids, or contaminated objects.

•Symptoms: High fever, fatigue, severe headache, and body aches.

•Lesions develop on the face, arms, and legs, progressing uniformly from macules to pustules.

•Complications: High mortality rate, severe scarring, blindness (if eye involvement occurs).

•Prevention: Eradicated globally by the World Health Organization (WHO) vaccination program; routine vaccination no longer performed.

how are bacterial and viral conjunctivitis different?

Bacterial conjunctivitis is caused by bacteria and often results in thick, yellow-green discharge, while viral conjunctivitis is usually due to viruses and presents with watery discharge and accompanying cold symptoms.

What causes ringworm?

•Tinea infections, commonly referred to as ringworm, are caused by dermatophytes, , specifically species of Trichophytonor Microsporum, that thrive on keratin in the skin, hair, and nails. These infections vary by location on the body.

•Tinea capitis: Ringworm on the scalp, scaly circular patches of hair loss

•Tinea corporis: Ringworm on the body, presenting as round, red, scaly patches with a clear center.

•Tinea pedis (Athlete’s Foot): Itchy, cracked skin on the foot, caused by prolonged moisture.

•Tinea cruris (Jock Itch): Rash in the groin area, often exacerbated by friction and moisture.

•These infections are typically treated with topical antifungal agents, and in severe cases, oral antifungal medications.

How is leishmaniasis contracted?

•Ulcerative skin sores from Leishmania parasite via sandflies. Found in Latin America, Middle East, South Asia.

What parasite might you get is you use tap or contaminated water to soak your contact lenses?

Acanthamoeba Keratitis

What is river blindness?

•Parasitic worm Onchocerca volvulus, transmitted by blackfly bites in fast-flowing rivers, mainly in sub-Saharan Africa and Latin America.

•Wolbachia bacteria, living symbiotically within Onchocerca volvulusworms, trigger severe inflammation when the worms die, contributing to eye damage and blindness

•Severe itching, rashes, and skin nodules.

•Progressive vision loss, photophobia, leading to blindness.

•Treatment/Prevention: Mass administration of ivermectin and blackfly control efforts significantly reduce infection rates and symptoms.

Why are some protozoa more resistant to environmental stress?

Protozoa may develop cysts or protective barriers to withstand adverse conditions such as desiccation, extreme temperatures, and lack of nutrients, enhancing their survival during unfavorable environmental stress.

define a nosocomial infection and name one common nosocomial pathogen

A nosocomial infection is an infection acquired in a healthcare setting, often due to medical procedures or devices. One common nosocomial pathogen is Staphylococcus aureus.

pathogen responsible for scarlet fever

is Streptococcus pyogenes, a bacterium that causes throat infections and skin infections, leading to scarlet fever symptoms.

pathogen responsible for whooping cough

Bordetella pertussis

how does the mucocillary escalator protect the lungs

Cilia line the respiratory tract, moving mucus and trapped particles toward the throat.

• Prevents pathogens and debris from reaching the lungs.
• Smoking, pollution, and chronic infections can impair this mechanism.

differentiate between bacterial and viral pneumonia based on symptoms.

Bacterial pneumonia typically presents with a sudden onset of symptoms, including high fever, chills, and chest pain, while viral pneumonia often has a more gradual onset with milder symptoms such as cough and low-grade fever.

the Mantoux test detects exposure to which disease by measuring the skins reaction to an injected purified protein derivative (PPD)?

he Mantoux skin test for tuberculosis involves injecting the subject with tuberculin protein derivative.
The injection should initially produce a raised wheal. (b) The test should be read in 48–72 hours. A positive
result is indicated by redness, swelling, or hardness; the size of the responding region is measured to
determine the final result.

tuberculosis

how does Mycobacterium tuberculosis survive inside macrophages?

Mycobacterium tuberculosis inhibits phagosome-lysosome fusion, allowing it to persist and replicate within macrophages, evading the host's immune response.

what is a characteristic symptom of diphtheria?

Caused by Corynebacterium diphtheriae, a Gram-positive, toxin-
producing bacterium.
• Symptoms:
• Severe sore throat, fever, and swollen lymph nodes.
• Formation of a thick, gray pseudomembrane in the throat or nasal
passages, which can obstruct breathing.

• Complications:
• Myocarditis: Inflammation of the heart muscle, which can lead to heart
failure.
• Neuritis: Nerve inflammation, potentially causing paralysis, especially in the
throat and diaphragm.
• Paralysis: If the toxin spreads, it can cause paralysis in limbs and
respiratory muscles, leading to respiratory failure.

• Prevention:
• DTaP Vaccine (Diphtheria, Tetanus, and Pertussis): Provides effective
protection; booster doses recommended for continued immunity.

• Treatment:
• Antitoxin: Neutralizes the diphtheria toxin; essential to administer as early
as possible to prevent toxin spread.
• Antibiotics: Typically penicillin or erythromycin, used to kill C. diphtheriae
bacteria and prevent further toxin production.

What causes “walking pneumonia” and how is it unique?

Mycoplasma pneumoniae:
• Causes "walking pneumonia," a milder form that may not require
hospitalization.
• Common in older children, teens, and young adults.
• Macrolides (e.g., azithromycin), as it lacks a cell wall, making it resistant to
penicillin.

Neisseria meningitidis infections are often characterized by which striking symptom?

a petechial rash that may progress to purpura.

How can viral and bacterial pneumonias be distinguished by appearance with a chest X-ray?

A chest radiograph of a patient with pneumonia shows the consolidations (lesions) present as opaque patches.

bacterial- localized inflammation

viral-diffuse, widespread inflammation

What are the signs and symptoms of measles, fifth disease, roseola, and rubella?

rubella Symptoms: Mild fever and rash.
• Serious Complications: Congenital rubella syndrome (CRS) in pregnant women, leading to birth
defects including deafness, heart defects, and intellectual disabilities

measles Symptoms: High fever, cough, conjunctivitis, and a characteristic red rash.
• Complications: Severe in young children, with high mortality rates in unvaccinated populations; can
lead to pneumonia and encephalitis

fifth disease Symptoms: "slapped cheek" rash, fever, and mild cold-like symptoms. Complications: Generally mild but can cause anemia in those with certain health conditions.

roseola Symptoms: Sudden high fever followed by a rash as the fever subsides. Complications: Typically mild; may cause febrile seizures in young children.

why is congenital rubella a concern?

Congenital rubella syndrome (CRS) in pregnant women, leading to birth
defects including deafness, heart defects, and intellectual disabilitie

how is zinc transmitted, and what are the risk of infection during pregnancy?

Zinc is transmitted through maternal dietary intake and is crucial for fetal development. Deficiencies during pregnancy can increase the risk of preterm birth, low birth weight, and developmental delays.

who might be the most likely to get Q fever?

Zoonotic disease caused by Coxiella burnetii, an intracellular
bacterium.
• Primarily affects people in contact with livestock (cattle,
sheep, goats).

How might you accidentally contract hantavirus?

Hantavirus can be contracted through exposure to infected rodent droppings, urine, or saliva, particularly in areas where rodents are present. It may also be transmitted through inhalation of aerosolized particles and, in rare cases, through bites from infected rodents.

what is lemierres syndrome?

Lemierre's syndrome is a rare but serious condition characterized by thrombophlebitis of the internal jugular vein, usually following an oropharyngeal infection. It can lead to septic emboli and systemic complications, including septic shock.

what is a common source for legionella outbreaks?

Water systems, such as showers or hot tubs, and evaporative cooling systems.

contrast antigenic drift vs. shift as it relates to influenza.

Antigenic drift refers to small, gradual changes in the virus's antigens due to mutations over time, which can lead to seasonal influenza epidemics.

antigenic shift involves a significant change that occurs when two different strains of the virus combine, potentially leading to pandemics.

what surface molecule does the SAR-CoV-2 virus recognize in host cells?

The SARS-CoV-2 virus recognizes the ACE2 receptor on host cells.

what animal vector carries MERS-CoV?

The dromedary camel is the primary animal vector that carries MERS-CoV, transmitting the virus to humans.

what does “immune privilege” in the brain mean, and why does it complicate treatment of CNS infections?

Immune privilege in the brain refers to the specialized environment that limits immune responses, protecting neural tissue from damage but making it difficult to treat central nervous system (CNS) infections, as effective immune responses are often muted.

meningitis involves inflammation of the

inflammation of the meninges,
often caused by bacterial or viral infections.
Symptoms include fever, severe headache,
stiff neck, and confusion

encephalitis involves inflammation of the

nflammation of brain tissue,
usually viral, leading to symptoms such as
fever, headache, lethargy, seizures, and
behavioral changes.

the Hip vaccine, given in childhood, protects against which pathogen? what kind of disease does this pathogen cause?

The Hib vaccine protects against Haemophilus influenzae type b, which can cause severe illnesses such as meningitis and pneumonia in young children.

how is neisseria meningitidis most commonly transmitted? characteristic disease symptoms?

Neisseria meningitidis is most commonly transmitted through respiratory droplets from infected individuals. Symptoms of the disease, known as meningococcal disease, include fever, headache, stiff neck, skin rash, and in severe cases, septicemia.

which animals are the primary reservoirs for rabies in most regions?

skunk and raccoon

the characteristic shape of the rabies virus is

bullet-shaped or rod-shaped.

rabies is a zoonotic virus that does not require an intermediate host. describe how rabies is transmitted and its progression in humans.

Nearly always fatal zoonotic disease caused
by the rabies virus
• Spread primarily through bites from infected
mammals (e.g., dogs, bats)
• Path of Infection and Symptoms
• Virus travels from bite site to the CNS via
peripheral nerves, causing encephalitis
• Symptoms progress: fever → agitation
→ hydrophobia → paralysis → death
• Diagnosis: Usually confirmed postmortem by
detecting Negri bodies in brain tissue. PCR
tests on saliva and skin biopsies used in
clinical cases.
• Treatment: Immediate post-exposure
prophylaxis (PEP) with rabies vaccine and
rabies immune globulin

infant botulism is often linked to the ingestion of which food product

honey, which contains spores.

Hansens disease (leprosy) can be transmitted to humans through prolonged contact with infected individuals or animals, such as?

Primarily affects the peripheral nervous system
(PNS), causing nerve damage, sensory loss, and
physical deformities.
• Transmission: Slow, requires prolonged contact;
not highly contagious due to natural immunity in
~95% of people; spread by nasal inhalation or skin
contact; armadillos can also transmit.
• Symptoms: Skin lesions, numbness, and, in
severe cases, loss of extremities.
• Treatment: Multi-drug antibiotics (dapsone,
rifampicin, clofazimine); no effective vaccine.

what is the primary mode of transmission for Naegleria Fowleri?

Naegleria fowleri is primarily transmitted through water entering the body via the nose, often during water-related activities in warm freshwater environments.

what is the risk of group B streptococcus infections in neonates?

Group B streptococcus infections in neonates can lead to severe outcomes, including pneumonia, sepsis, and meningitis, primarily if the bacteria are transmitted from the mother during childbirth.

how is poliovirus transmitted? how can this virus go from asymptomatic paralytic?

Fecal-oral route, primarily infecting the intestinal tract

and can lead to neurological complications, including paralysis.

what causes infectious mononucleosis and how can you catch it?

Infectious mononucleosis, commonly caused by the Epstein-Barr virus (EBV), is transmitted through saliva, often through kissing or sharing drinks.

how do babies typically contract cronobacter meningitis?

Babies typically contract cronobacter meningitis through consumption of contaminated powdered infant formula or from environmental sources. This bacterium can lead to severe illness, including meningitis and sepsis.

what foods are considered most risky for listeria monocytogenes contamination, and how can this pathogen use host molecules as propulsion to invade the brain?

Foods such as unpasteurized dairy products, deli meats, and smoked seafood are considered most risky for listeria monocytogenes contamination. This pathogen can utilize host cell actin to propel itself into adjacent cells, facilitating invasion.

how does prion disease occur

Prion disease occurs when misfolded prion proteins induce normal proteins in the brain to also misfold, leading to neurodegeneration and brain damage. These diseases are often transmissible and can be inherited or acquired through exposure.

bacterial meningitis based on csf findings

is characterized by elevated white blood cell counts, predominantly lymphocytes, increased protein levels, and low glucose concentrations in cerebrospinal fluid (CSF). This profile helps differentiate it from viral meningitis.

viral meningitis based on csf findings

is characterized by elevated white blood cell counts, predominantly lymphocytes, normal protein levels, and normal glucose concentrations in cerebrospinal fluid (CSF). This distinct profile differentiates it from bacterial meningitis.

define molecular mimicry and give one example of an infection that triggers autoimmunity

Molecular mimicry is a phenomenon where pathogens possess antigens resembling host tissue, leading to an autoimmune response. An example is rheumatic fever, which can occur after a streptococcal infection.

pathogen for yersinia pestis

is a bacterium belonging to the Yersinia genus, known for causing the plague. It is transmitted through infected fleas or direct contact with infected animals.

hallmark symptom of brucellosis

is undulant fever, characterized by cyclical fever patterns and other flu-like symptoms.

primary mode of transmission for cat-scratch disease

Cat scratch or bite from an infected cat

how would a person contract Lyme disease

A person can contract Lyme disease through the bite of an infected tick, typically found in wooded or grassy areas.

primary organ for Lyme disease

The primary organ affected by Lyme disease is the skin, particularly leading to rashes like erythema migrans.

what type of organism causes malaria, and what two places in the human body do different life cycle stages of the pathogen reside during infection?

Caused by the Plasmodium parasite, which resides in the liver and red blood cells.

compare and contrast toxins produced by vibrio cholerae and clostridium difficile

Both Vibrio cholerae and Clostridium difficile produce potent toxins that disrupt cellular functions, but Vibrio cholerae primarily causes a massive loss of electrolytes leading to severe dehydration through its cholera toxin, while Clostridium difficile's toxins primarily induce inflammation and damage to the intestinal lining.

what molecular mechanism does cholera toxin cause its hallmark symptom

of profuse watery diarrhea by increasing intracellular levels of cAMP in intestinal epithelial cells.

helicobacter pylori infection is associated with what disease symptoms

such as chronic gastritis and peptic ulcers in the stomach and duodenum.

what is the major virulence factor of E.coli O157:H7

Shiga toxin, which inhibits protein synthesis in host cells.

how might one get cryptosporidiosis

by ingesting contaminated water or food, often from fecal-oral transmission.

describe the characteristic lesion of primary syphilis

the chancre, a painless ulcer at the site of infection, typically on the genitalia, anus, or mouth.

vaginal candidiasis is most commonly caused by which organism

Candida albicans, a yeast.

trichomoniasis is characterized by which symptom

vaginal itching and discharge, as well as discomfort during intercourse.

what infections cause pelvic inflammatory disease (PID)

Chlamydia trachomatis and Neisseria gonorrhoeae, among others.

what causes lymphogranuloma venereum

Lymphogranuloma venereum is caused by specific strains of the bacterium Chlamydia trachomatis.