Bacterial Diseases: Sexually Transmitted, Contact, Soilborne, and Arthropodborne Pathogens

Comprehensive practice flashcards reviewing bacterial sexually transmitted infections, urinary tract infections, contact diseases, and soilborne and arthropodborne pathogens based on lecture materials.

Combination Therapy for Gonorrhea

The CDC-recommended regimen for uncomplicated genital, rectal, and pharyngeal gonorrhea consisting of ceftriaxone $250\text{ mg}$ as a single intramuscular dose plus either azithromycin $1\text{ g}$ orally in a single dose or doxycycline $100\text{ mg}$ orally twice daily for $7\text{ days}$.

PPNG Strains

Penicillinase-producing Neisseria gonorrhoeae strains, first identified in 1976, that carry plasmid-borne genes encoding penicillinase (beta-lactamase) conferring resistance to penicillin.

Neisseria gonorrhoeae

A fastidious, Gram-negative diplococcus with a characteristic kidney-bean shape that infects mucosal epithelium of the urogenital tract, rectum, pharynx, and conjunctiva.

Salpingitis

Inflammation and potential tubal occlusion of the fallopian tubes caused by ascending gonococcal or chlamydial infection, which significantly elevates the risk of ectopic pregnancy and tubal factor infertility.

Disseminated Gonococcal Infection (DGI)

A severe systemic manifestation of gonorrhea resulting from hematogenous spread of Neisseria gonorrhoeae, leading to septic arthritis, tenosynovitis, and endocarditis or meningitis.

Chlamydia trachomatis

An obligate intracellular parasitic bacterium and the causative agent of the most frequently reported bacterial STI in the United States, presenting with dimorphic life-cycle stages.

Elementary Body (EB)

The small, extracellular, metabolically inert, infectious form of Chlamydia trachomatis specialized for survival outside the host and entry into epithelial cells.

Reticulate Body (RB)

The larger, intracellular, metabolically active, noninfectious form of Chlamydia trachomatis that replicates via binary fission within host membrane-bound vacuolar inclusions.

Pelvic Inflammatory Disease (PID)

A generic clinical designation for an ascending infection of the upper female genital tract—including the endometrium, fallopian tubes, and ovaries—commonly resulting from untreated chlamydial or gonococcal infections.

Dyspareunia

Pain experienced during sexual intercourse, serving as a prominent clinical symptom of pelvic inflammatory disease, cervicitis, or deep tissue inflammation in women.

Nucleic Acid Amplification Test (NAAT)

A molecular diagnostic technique, such as polymerase chain reaction (PCR), that amplifies bacterial DNA or RNA to detect Chlamydia trachomatis or Neisseria gonorrhoeae with superior sensitivity and specificity in urine or swabs.

Treponema pallidum

A fastidious spirochete bacterium that causes syphilis, an exclusively human systemic sexually transmitted infection characterized by multi-stage progression if left untreated.

Hard Chancre

A painless, indurated circular red-purple ulcer with raised borders that seeps infectious clear fluid rich in Treponema pallidum, developing at the primary site of bacterial entry.

Primary Syphilis

The earliest clinical stage of syphilis occurring $10\text{ to }90\text{ days}$ (average $2\text{ to }4\text{ weeks}$) after exposure, marked by a solitary or multiple hard chancres that heal spontaneously within $3\text{ to }6\text{ weeks}$.

Secondary Syphilis

The disseminated systemic stage of syphilis occurring $4\text{ to }8\text{ weeks}$ post-chancre, characterized by generalized lymphadenopathy, fever, and a symmetric copper-colored maculopapular rash on the body, palms, and soles.

Condyloma Lata

Moist, highly infectious, flattened reddish-brown or purple papular lesions that develop in warm intertriginous skin folds and mucous membranes during secondary syphilis.

Latent Syphilis

A clinically silent phase of syphilis characterized by serologic reactivity in the absence of clinical lesions, subcategorized into early latency (first year after lesion resolution) and late latency.

Gummas

Soft, painless, gummy-granular non-infectious granulomatous destructive lesions characteristic of tertiary benign syphilis that develop in skin, bone, the liver, or mucosal tissues.

Neurosyphilis

Central nervous system infection by Treponema pallidum occurring $4\text{ to }25\text{ years}$ post-infection in $6.5\%$ of untreated patients, manifesting as chronic meningitis, dementia, sensory ataxia, or paresis.

Tabes Dorsalis

A form of neurosyphilis (syphilitic myelopathy) resulting from progressive slow demyelination of the sensory neurons in the dorsal columns of the spinal cord, leading to ataxia and lancinating pain.

General Paresis

A severe neurosyphilitic complication characterized by progressive dementia, dysarthria, tremors, myoclonus (muscle twitching), seizures, and generalized cortical impairment.

Argyll-Robertson Pupil

A bilateral pupillary abnormality associated with neurosyphilis, colloquially designated 'prostitute's pupil,' in which the pupils constrict upon accommodation for near vision but fail to react to light.

Early Congenital Syphilis

Vertical transmission of Treponema pallidum presenting in infants up to $2\text{ years}$ of age, clinically characterized by poor feeding, hepatosplenomegaly, skeletal lesions, and snuffles (syphilitic rhinitis).

Pemphigus Syphiliticus

A distinctive bullous cutaneous eruption with a red, infiltrated base that appears on the palms and soles of neonates with congenital syphilis.

Venereal Disease Research Laboratory (VDRL) Test

A nontreponemal microflocculation screening assay that detects non-specific serum or spinal fluid antibodies (reagin) reacting against cardiolipin-lecithin-cholesterol antigens.

Rapid Plasma Reagin (RPR) Test

A macroscopic nontreponemal flocculation test using cardiolipin, lecithin, and carbon particles to visualize reagin antibodies as macroscopic black clumps.

Cardiolipin

A diphosphatidylglycerol lipid antigen extracted from bovine (ox) heart muscle used in nontreponemal assays (VDRL and RPR) to react with anti-lipoidal reaginic antibodies.

Fluorescent Treponemal Antibody Absorption (FTA-ABS) Test

An indirect immunofluorescence confirmatory assay that detects specific IgG and IgM antibodies against Treponema pallidum after absorbing out non-specific treponemal antibodies.

Treponema pallidum Particle Agglutination (TPPA) Assay

A treponema-specific serologic confirmation method employing gelatin particles sensitized with Treponema pallidum antigens to bind and agglutinate serum treponemal antibodies (not performed on CSF).

Yaws

A chronic non-venereal treponemal infection endemic to tropical regions, caused by Treponema pallidum subspecies pertenue, affecting skin, cartilage, and bone.

Bejel

An endemic non-venereal treponematosis caused by Treponema pallidum subspecies endemicum, transmitted by direct contact or shared drinking vessels, primarily manifesting with oral mucous patches.

Pinta

A non-venereal cutaneous treponematosis caused by Treponema carateum that presents with pruritic, scaly skin lesions followed by dyschromic patches and late blue hyperpigmentation.

Haemophilus ducreyi

A fastidious, pleomorphic Gram-negative coccobacillus requiring only approximately $100\text{ cells}$ to transmit chancroid and initiate painful genital ulcerations.

Soft Chancre

A painful, non-indurated genital ulcer with ragged, undermined edges and a purulent, bleeding base, pathognomonic for chancroid.

Lymphogranuloma Venereum (LGV)

A systemic sexually transmitted infection caused by Chlamydia trachomatis invasive serotypes L1, L2, or L3, characterized by painless transient genital nodules followed by suppurative inguinal lymphadenitis.

Jersild Syndrome

The tertiary clinical stage of lymphogranuloma venereum (anogenitorectal syndrome) manifested by rectal strictures, tissue fistulae, perianal abscesses, and elephantiasis of the genitalia.

Granuloma Inguinale (Donovanosis)

A chronic, slowly destructive genital ulcer disease caused by Klebsiella granulomatis, presenting with painless, highly vascular, beefy-red velvety nodules that bleed readily on contact.

Donovan Bodies

Clusters of encapsulated, pleomorphic Klebsiella granulomatis bacilli showing bipolar 'safety-pin' staining within large mononuclear macrophages on stained tissue smears.

Gardnerella vaginalis

A facultatively anaerobic, Gram-variable rod that outcompetes normal hydrogen peroxide-producing lactobacilli in the vagina to cause bacterial vaginosis with a characteristic fishy amine odor.

Clue Cells

Vaginal squamous epithelial cells studded and coated with dense coccobacilli that obscure their cell margins, serving as the microscopic hallmark of bacterial vaginosis.

Ureaplasma urealyticum

A wall-less, urea-hydrolyzing bacterium associated with nongonococcal urethritis, chorioamnionitis, and adverse pregnancy outcomes including premature birth.

Mycoplasma hominis

A wall-less opportunistic bacterium isolated from the endometria and fallopian tubes of approximately $10\%$ of women with salpingitis, contributing to bacterial vaginosis and pelvic infections.

Urethritis

Inflammation of the urethra causing dysuria, urinary frequency, and burning micturition, most frequently initiated by ascending entry of Escherichia coli or sexually transmitted pathogens.

Cystitis

Infection and inflammation of the urinary bladder marked by suprapubic pelvic discomfort, urgent micturition, dysuria, and turbid or blood-tinged urine, primarily caused by Escherichia coli.

Prostatitis

Bacterial inflammation of the prostate gland resulting in chills, fever, perineal or lower back pain, dysuria, and urinary hesitancy, caused by coliforms or staphylococci ascending from the urethra.

Pyelonephritis

A high-acuity bacterial infection of the renal parenchyma and pelvis presenting with costovertebral flank pain, systemic rigors, high fever, dysuria, and abdominal discomfort.

Significant Bacteriuria Diagnostic Threshold

The standard laboratory culture criterion for confirming a urinary tract infection, defined as a colony count exceeding $100{,}000\text{ CFU/ml}$ of a single bacterial species in a clean-catch midstream urine sample.

Pyuria

The presence of elevated leukocytes in the urine, defined diagnostically as greater than or equal to $10\text{ WBCs per high-power field}$ on microscopic examination.

Cutibacterium acnes

An aerotolerant anaerobic Gram-positive rod indigenous to the skin that proliferates within sebum-impacted pilosebaceous follicles, triggering inflammatory acne vulgaris.

Comedones

Primary non-inflammatory follicular plugs created by the abnormal cohesion of shed keratinocytes and sebum within the pilosebaceous canal, categorized into open or closed forms.

Blackhead (Open Comedo)

A wide-open, plugged pilosebaceous pore filled with compacted keratin, lipids, and oxidized melanin, presenting as a darkened follicular plug at the epidermal surface.

Whitehead (Closed Comedo)

A completely covered, microscopic or palpable blockage of trapped sebum and cellular debris beneath an intact layer of epidermis with an obstructed follicular orifice.

Furuncle (Boil)

A localized, tender, circumscribed follicular abscess that extends deep into the dermis and subcutaneous tissue, typically caused by Staphylococcus aureus.

Carbuncle

A coalescent cluster of multiple communicating furuncles extending deep into the subcutaneous fascia and draining through multiple follicular orifices, frequently accompanied by systemic fever.

Impetigo Contagiosum

A highly communicable superficial cutaneous infection characterized by thin-walled intraepidermal vesicles that rupture and dry into characteristic honey-colored, amber crusts.

Scalded Skin Syndrome (Ritter's Disease)

A severe dermatologic disorder of neonates and infants caused by exfoliative exotoxins of Staphylococcus aureus, resulting in widespread erythema, skin flaccidity, and detachment of the epidermis.

Toxic Shock Syndrome Toxin-1 (TSST-1)

A potent superantigen exotoxin synthesized by Staphylococcus aureus that cross-links MHC class II molecules and T-cell receptors, triggering massive polyclonal T-cell activation and massive cytokine storm.

Streptococcus pyogenes

A Group A beta-hemolytic Gram-positive coccus arranged in chains that exhibits diverse cell-associated and secreted virulence factors causing pyogenic infections, erysipelas, and necrotizing fasciitis.

Necrotizing Fasciitis

A rapidly advancing, life-threatening bacterial gangrene that tracks along subcutaneous deep fascia, characterized clinically by disproportionate pain relative to visible skin findings, tissue edema, and $15\%$ mortality.

C5a Peptidase

A surface-anchored endopeptidase produced by Streptococcus pyogenes that specifically degrades the complement-derived neutrophil chemoattractant C5a, delaying early polymorphonuclear recruitment.

Streptolysin O

An oxygen-labile, immunogenic, pore-forming cholesterol-dependent cytolysin produced by Streptococcus pyogenes, against which elevated host neutralizing serum antibodies (ASO titer) confirm recent infection.

Streptolysin S

An oxygen-stable, non-immunogenic, cardiotoxic oligopeptide hemolysin of Streptococcus pyogenes that creates the clear beta-hemolytic zone around colonies on sheep blood agar and poisons platelets and neutrophils.

Streptococcal Pyrogenic Exotoxins (SpeA and SpeC)

Bacteriophage-encoded superantigenic exotoxins of Streptococcus pyogenes responsible for the scarlatinal exanthem and the multiorgan dysfunction seen in streptococcal toxic shock-like syndrome.

Streptokinase

An extracellular streptococcal protein that forms a complex with host plasminogen, catalyzing its transformation to plasmin to degrade surrounding fibrin clots and facilitate invasive bacterial spread.

Streptodornase

A family of four extracellular deoxyribonucleases (DNases) secreted by Streptococcus pyogenes that liquefy viscous purulent exudates and dismantle the DNA meshwork of neutrophil extracellular traps (NETs).

Erysipelas

An acute, superficial lymphatic cellulitis of the face or lower extremities caused by Streptococcus pyogenes, presenting with intense constitutional fever and an elevated, fiery-red, demarcated indurated plaque.

Cellulitis

A non-necrotizing, acute spreading inflammation of dermal and subcutaneous loose connective tissues causing localized erythema, warmth, and ill-defined swelling without sharp margination.

Pasteurella multocida

A small, facultatively anaerobic Gram-negative rod colonizing the nasopharynx of domestic dogs and cats that causes rapid cellulitis, severe pain, and tissue abscesses following animal bite punctures.

Bartonella henselae

A fastidious, slow-growing Gram-negative bacterium transmitted by cat scratches, bites, or cat fleas, responsible for cat-scratch disease and vascular bacillary angiomatosis.

Bacillary Angiomatosis

A pseudoneoplastic vascular proliferative disorder occurring in immunocompromised individuals infected with Bartonella henselae, in which proliferating endothelial cells form blood vessel masses.

Actinobacillus muris

Formerly designated Streptobacillus moniliformis, a Gram-negative rodent commensal that causes North American rat-bite fever, presenting with prolonged fever, migratory polyarthritis, and a maculopapular rash.

Spirillum minus

A short, rigid, flagellated spiral bacterium that causes the Asian variant of rat-bite fever known as sodoku, clinically recognized by indurated bite-site ulceration and recurrent fever.

Blepharitis (Stye / Hordeolum)

An acute localized, painful, erythematous purulent infection of a sebaceous gland situated at the margin of the eyelid, most commonly precipitated by Staphylococcus aureus.

Trachoma

A chronic conjunctivitis caused by Chlamydia trachomatis serotypes A, B, Ba, and C, characterized by conjunctival follicular scarring, entropion, trichiasis, and corneal opacification.

Pseudomembranous Colitis

A severe form of antibiotic-induced colitis caused by Clostridium difficile toxins, pathologically defined by inflammatory exudative pseudomembranes overlying an ulcerated colonic mucosa.

Mycobacterium leprae

An obligate intracellular, acid-fast bacillus displaying predilection for Schwann cells and histiocytes in cool peripheral sites ($30^\circ\text{C}$), serving as the etiological agent of leprosy (Hansen disease).

Phenolic Glycolipid-I (PGL-I)

A major species-specific surface cell-wall glycolipid of Mycobacterium leprae that binds directly to the basal lamina of Schwann cells, triggering bacterial internalization and peripheral neuropathy.

Tuberculoid Leprosy (Paucibacillary)

A contained, non-contagious clinical manifestation of leprosy occurring in patients with strong cell-mediated immunity, marked by fewer than $5\text{ hypopigmented}$, hypoaesthetic skin plaques and a positive lepromin skin test.

Lepromatous Leprosy (Multibacillary)

The widespread, contagious form of leprosy seen in patients with defective cell-mediated immunity, presenting with diffuse infiltrating nodules, loss of eyebrows, leonine facies, and negative lepromin reactivity.

Lepromin Skin Test

A diagnostic intradermal test utilizing killed Mycobacterium leprae antigens to evaluate the integrity of host cell-mediated immunity; it is positive in tuberculoid leprosy and negative in lepromatous leprosy.

Leprosy Globi

Aggregated intracellular globular masses of innumerable acid-fast Mycobacterium leprae bacilli packed within lipid-laden foamy macrophages, visible on Ziehl-Neelsen stained smears of lepromatous tissues.

Bacillus anthracis

A large, aerobic, Gram-positive, endospore-forming rod whose virulence is mediated by an antiphagocytic poly-D-glutamic acid capsule and an AB-type tripartite plasmid-borne exotoxin complex.

Protective Antigen (PA)

The central $83\text{-kDa}$ receptor-binding component of the anthrax toxin that binds host TEM8 or CMG2 receptors, is cleaved to $PA_{63}$, oligomerizes, and translocates Edema Factor and Lethal Factor into host cytosol.

Edema Factor (EF)

A calmodulin-dependent adenylate cyclase exotoxin produced by Bacillus anthracis that raises host intracellular cyclic AMP levels, causing profound fluid extravasation and extensive tissue edema.

Lethal Factor (LF)

A zinc-dependent metalloprotease toxin of Bacillus anthracis that cleaves host mitogen-activated protein kinase kinases (MAPKKs), paralyzing cell signaling and triggering macrophage apoptosis.

Cutaneous Anthrax

The most common form of anthrax ($\sim 95\%$ of cases), initiated by skin spore entry that forms an itchy vesicle evolving into a depressed, painless, necrotic black eschar bordered by extensive edema.

Inhalation Anthrax

The most lethal form of anthrax (woolsorter's disease), initiated by inhaling aerosolized endospores that germinate within mediastinal lymph nodes to produce hemorrhagic mediastinitis and rapid fatal shock.

Clostridium tetani

An obligate anaerobic, spore-forming Gram-positive rod bearing terminal round spores ('tennis-racket' shape) that contaminates deep puncture wounds to cause tetanus.

Tetanospasmin

A potent neurotoxic AB exotoxin produced by Clostridium tetani that cleaves synaptobrevin to block the vesicular exocytosis of inhibitory neurotransmitters (glycine and GABA), causing spastic paralysis.

Trismus (Lockjaw)

A state of persistent, painful spastic contraction of the masseter and temporalis jaw muscles caused by tetanospasmin, clinically preventing mouth opening.

Opisthotonus

A severe neurological manifestation of tetanus characterized by prolonged backward arching and rigid hyperextension of the head, spine, and lower extremities caused by sustained motor neuron firing.

Clostridium perfringens

An anaerobic, endospore-forming Gram-positive bacillus that secretes lethal necrotizing enzymes, including alpha-toxin (lecithinase), to induce gas gangrene (clostridial myonecrosis).

Gas Gangrene (Clostridial Myonecrosis)

A rapidly spreading, necrotic soft-tissue infection marked by severe wound pain, gaseous crepitus, foul-smelling watery discharge, and extensive tissue putrefaction.

Leptospira interrogans

An aerobic spirochete characterized by tightly coiled hooks at its ends and undulant motility, excreted in the urine of mammalian reservoirs and transmitted through water to cause leptospirosis.

Weil's Disease

A severe icteric complication of leptospirosis occurring in approximately $10\%$ of cases, characterized by hepatic failure, marked jaundice, acute kidney injury, and hemorrhagic diathesis.

Burkholderia pseudomallei

A motile, Gram-negative saprophytic bacillus found in soil and water across tropical regions that causes melioidosis, capable of establishing latent subclinical infections ('medical time bomb').

Yersinia pestis

A Gram-negative, facultatively anaerobic coccobacillus showing bipolar 'safety-pin' staining that causes plague, transmitted primarily through the bite of the Oriental rat flea.

Buboes

Exquisitely tender, markedly enlarged, and suppurative regional lymph nodes that typically develop in the groin, axilla, or cervical regions in patients with bubonic plague.

Francisella tularensis

A highly infectious, pleomorphic Gram-negative facultative intracellular coccobacillus causing tularemia, transmitted by tick bites, deer flies, or direct contact with infected lagomorphs (rabbits).

Borrelia burgdorferi

A tick-borne spirochete transmitted by Ixodes ticks that causes Lyme disease, clinically recognizable in its localized primary stage by an expanding erythema migrans ('bull's-eye') rash.