Question

Question 4 Answer both of the following: a) Provide an overview of urinary tract infections (UTIs). Include in your answer risk factors associated with UTIs, common aetiological agents, and mechanisms of pathogenesis. (15 marks) b) Chlamydia causes important sexually transmitted infections. Provide an overview of chlamydia, including transmission, disease presentation, diagnosis, and preventative strategies. (15 marks)

Answer 1

Urogenital Tract Infections •The urogenital tract consists-organs & glands that are involved in production, storage and discharge of urine and involved in reproduction. •Organs for urine production, storage and discharge are the kidneys, ureters, urinary bladder and urethra. •The male repd. tract shares the urethra with the urinary tract. •The female repd tract is distinct from the urinary tract and consists of the ovaries, fallopian tubes, uterus, vagina. Introduction • Urinary tract infection (UTI) is a collective term that describes any infection involving any part of the urinary tract, namely the kidneys, ureters, bladder and urethra. • Associated with inflammatory response of urothelium to bacterial invasion that is usually associated with bacteriuria and pyuria. • Marked by the presence of micro- organisms including E. coli (> 75%), Klebsiella Proteus mirabilis, Enterococcus faecalis and Staphylococcus pneumoniae, saprophyticus Upper tract: Ureter, Kidneys Pyelonephritis UTI Lower tract: bladder and urethra Cystitis, Prostatitis, Urethritis Both upper and lower tract infections are further divided into complicated and uncomplicated infections.

Etiological agents: E. coli 75-90% Stap. saprophyticus 10-20% Klebsiella 3-4% Enterococcus 2-3% Proteus 2-3% Other 3% Epidemiology • Worldwide , all age group ► 150 million new cases every year across the globe. > > 2 million cases with complicate symptoms, > 1 million emergency department visit whereas 300,000 hospitalizations annually. • Age group In infants, (< 6 months), its more prevalent in males: PUV After infancy, UTI majorly effects females. • 40-50% in women vs 0.04% in men. •> 10% women have recurrent UTI • Between age of 5-14: 1-2% of girls suffer with bacteriuria, incr to 10% after. • Recurrent infection: 20-40% whereas > 50% of women have reinfection after 40-50 ► Increases in pregnancy: Chances of UTI increases after menopause. Dec is estrogen, Lacto replaced by E. coli. In males, risk increases after 60s due to enlargement of prostate. Routes of infection •Ascending route: most common, •Hematogenous route or Blood borne spread •Lymphatogenous spread • Direct extension from other organs

Factors associated with UTIS Catheterisation Diabetes mellitus Complicated UTI Comorbidities in Spinal cord injury paediatric patients Other factors: > Pregnancy: Estrogen relax the smooth muscles in the urethra causing stasis which allows bacterial overgrowth Vesicoureteral reflux: Also associated with recurrent infection. Benign Prostatic Hypertrophy (BPH) is the most common causes in male > Uterine prolapse: Uterine muscles become weak and couldn't support uterus, may slip to vagina. > Neurogenic bladder > Use of spermicide (++ pH of vagina, toxic to lacto, E. coli adherence) Major cause of UTI Not urinating frequently enough and not fully emptying the bladder when urinating. This retained urine provides a suitable medium for bacterial growth often containing protein and sugars removed from circulation by the kidneys. Lack of hydration can lead to insufficient urine production, this in turn can lead to the development of a UTI. Poor hygienic conditions. Genetic factors: e.g.. Low TLR4 expression, Low IL-8 receptor expression Virulence factors • Surface factors Daca galete s de nit of Tolle (ILRAL activate muncelle n d pain of UTL type fimbris o lves interact binding and bioti formationstects renal filtration pyclonephritis Mending on Asation • I ndin active hap e and inducemic side and cytokine production • Capa antigen p on against phancytic engulfment and complemented and bestensidali the ecognized by complement system, cah, 3d due to increased amounts of capsular K e ctivity • Aerobacim trenuptake factors, siderophones • Secreted factors • Alphesin peming only enucleated cells, erable itens lo c al barriers d e eflector immune cells, and gain enhanced access to he r and iron stores. May indice endothelial damage and renal vasoconstriction and renal scarring • Secreted a wansporter toxin (SAT): Toxic against kidney cell lines + Tollimale 1) receptor ( R) d o maining protein (Tepi. • Colici Inhibits growth of other bacteria • Production of Preto Hydroly we increasing the plafurie. Tanie okidney leading to Smation of stones

Virulence factors Surface factors Pfimbriae: for adhesion to mucosal and tissue matrix and for the production of cytokines, binds to D-galactose-D-galactose moieties, ------- release of ceramide, an agonist of Toll-like receptor 4 (TLR4), activates immune cell response ----- inflammation and pain of UTI. ► type 1 fimbriae: involves inter-bacterial binding and biofilm formation--- affects renal filtration---- pyelonephritis. Mannose receptor binding adhesins. ► A43: self aggregation, • LPS: endotoxin, activate host response and to induce nitric oxide and cytokine production. • Capsule: antigenic variation, protection against phagocytic engulfment and complement-mediated bactericidal effect in the host (not recognized by complement system, C3, C3d) due to increased amounts of capsular K antigen activity. • Aerobactin: Iron uptake factors, siderophores. • Secreted factors • Alpha-hemolysin: pore-forming toxin, lyse nucleated host cells, enable pathogens to cross mucosal barriers, damage effector immune cells, and gain enhanced access to host nutrients and iron stores. May induce endothelial damage and renal vasoconstriction and renal scarring, • Secreted autotransporter toxin (SAT): Toxic against kidney cell lines. • Toll/interleukin (IL-1) receptor (TIR) domain-containing protein (Tcp). • Colicin: Inhibits growth of other bacteria. • Production of urease enzyme (Proteus sps): Hydrolyse urea, increasing the pH of urine----- toxic to kidney, leading to formation of stones.

Host pathogen relationship • The organism: E. coli - many strains present but only few cause infection (uropathogenic) Adhesins Toxins Pili CNF1 Afimbrial adhesins Haemolysin SPATES Capsule Siderophores Haem receptors O-antigen Cellulose Salmochelin Immune evasion Iron acquisition THE ABILITY TO CAUSE INFECTION- VIRULENCE FACTORS (VF) Toxins CNF-1a-hemolysin Iron uptake Aerobactin Enterobactin Hemin uptake Salmochelin Sit system Yersiniabactin Colibactin (pks) S-fimbrial adhesins ! (sfa 1) A Pilates chromosome outer membrane P-related fimbriae (pap. prf, prs) Capsule (K-antigen) cytoplasm periplasm inner membrane Type - fimbriae (fim) OmpA. Ag43 > > > Flagella (H-antigen) Curli Sasoog0000 900 goos TcpC O-antigen Jn repeat

Chlamydia trachomatis • gram negative, non-motile, aerobic, obligate intracellular parasites. • Belongs to family Chlamydiaceae. • Small in size. • Infects mucosal lining of urogenital tract • Replicate inside the vacuoles in the cytoplasm of cells. • Unique feature: unusual dimorphic life cycle • Unique cell wall: LPS membrane but NO peptidoglycan. Atachment and my Life cycle 1. Instalac e ) STARF inyect a con Col DE Rund Halth 1. Padalar 2. c on person a n • Elementary body Infectious spore, can survive outside the cell • Reticulate body: larger, metabolically active, found only within a host cell. • LPS can elicit strong inflammatory response and may lead to septic shock • Pathogenicity Islands: Encodes for various virulence factors, especially needle-like projection type III secretion apparatus that inject proteins directly from the bacteria into the cell cytoplasm and avoid lysosomes. . Chlamydia-infested vacuole divert lipids to itself rather than to another compartment of the host cell. • Proteins and regulatory factors produced by the cryptic plasmid: Plasmid less strains are unable to cause infection of upper genital tract in mice model, no LGV also. • The putative large cytotoxin: shares homology with other proteins.

After host cell entry, the EB is localized to a phagosome and the primary differentiation process is initiated. This developmental process involves the commencement of bacterial metabolism and the conversion of the EB to the intracellular replicating form of the organism, termed the reticulate body (RB) which replicates 200-500-folds by binary fission. Within 40-48 hours, the RBS transform back into infective EBs, which are subsequently released from the inclusion vacuole to infect neighbouring cells. In the presence of growth inhibitors, such as interferon-y, intracellular C. trachomatis bacteria acquire a non-replicating, persistent form called Aberrant Body (AB), which is refractory to treatment by a wide range of antibiotics and bacteria in this form differentiate back into infectious forms after removal of the inhibitor (Brunham et al., 2005, Yasser et al., 2005). Recently two exit mechanisms of Chlamydia from the host cells are established. Both mechanisms are mutually exclusive and involve highly contrasting strategies. The first is the spontaneous lysis of both the inclusion and the host cell. This appeared to occur as a result of an ordered sequence of permeabilization events, beginning with the rupture of the inclusion membrane and terminating with the permeabilization of the plasma membrane and the dispersal of Chlamydial Ebs. Diagnosis Sample collection: Endocervical/cervical swab • Urethral swab, • First void urine sample • Culture method • Gold standard of C. Iruchomatis in urogenital specimens: Specificity 100% • Preserves organism for further studies like biochemical and antimicrobial analysis • Draw hacks > Low Sensitivity: 75-90% (much lower than NAATs). Lose of infectivity during stringent cold chain transportation > requirement of high level technical expertise. time-consuming and laborious methodology delay in treatment. • Antigen detection Direct fluorescent antibody (DFA) test: fluorescien labeled monoclonal antibody specific for MOMP or LPS. 80-90% sensitive: 98-99% specific. visualization of distinctive morphology and staining characteristics of Chlamydial inclusion and EBs. No refrigeration of sample required, rapid test. Drawback: cross reactivity with other species. Technical expertise Presumptive in low prevalence regions. Enzyme immunoassay (EIA): employs enzyme conjugated polyclonal or monoclonal antibodies that detect Chlamydial LPS. Drawback: Cross reactivity with other bacterial with LPS. Low specificity

NAATS DNA hybridization probe: employs a chemiluminescent DNA probe hybridises specific sequence in Chlamydial 16S rRNA. Hybrid is absorbed on magnetic bead and fluorescence is estimated using luminometer. Sensitivity: 85 to 99%; specificity from 98 to 99% PCR based kits: detection limit of NAAT is as low as single gene copy, non-invasive sampling technique. Can detect the infection even in asymptomatic infected individuals. No viable organism required. Genes used: MOMP, rRNA encoding gene, • Treatment: Erythromycin, tetracycline and sulfa drugs. - both partners should be treated.