Urinary Tract Infections PDF

Urinary Tract Chapter 37 Introduction Upper urinary tract kidneys ureters Lower urinary tract bladder urethra prostate Urinary Tract Normal Flora Sterile above urethra, NF in urethra Coag-neg staph Enterobacteriaceae Corynebacterium...

Urinary Tract Chapter 37 Introduction Upper urinary tract kidneys ureters Lower urinary tract bladder urethra prostate Urinary Tract Normal Flora Sterile above urethra, NF in urethra Coag-neg staph Enterobacteriaceae Corynebacterium Anaerobic bacteria Micrococcus Yeast Streptococci Mycoplasma Terms Urinary tract infection (UTI) Microbial invasion of urinary system Very common Bacteriuria bacteria in urine Pyuria WBC in urine 4 Types of UTIs Cystitis (lower UTI) bladder infection dysuria with frequent urination Pyelonephritis (upper UTI) kidney infection fever, pain, dysuria, frequent urination 4 Types of UTIs Acute urethral syndrome (AUS) in young women dysuria, pyuria, bacteriuria Urethritis same sypmtoms as UTI, but considered sexually transmitted UTI Caused by endogenous flora E. coli (most common) other Enterobacteriaceae (Klebsiella) Staphylococcus saprophyticus (young women), S. aureus enterococci Pseudomonas AUS Caused by S. saprophyticus, Enterobacteriaceae, N. gonorrhoeae, C. trachomatis Routes of Infection Ascending route from urethra to bladder (to kidneys) Descending route carried by bloodstream to kidneys MTB and S. aureus Epidemiology Predisposing factors urinary tract abnormalities enlarged prostate kidney stones instrumentation catheterization underlying medical conditions diabetes mellitus Epidemiology Women most UTI occur in women short female urethra hormonal changes sexual activity pregnancy Men >60 years associated with enlarged prostate Nosocomial Infections UTI is most common nosocomial infection in US hospitals Onset preceded by catheterization and other instrumentation Specimen Collection & Transportation General consideration: urine inside body is sterile above urethra Contamination: urethral, vaginal, skin, fecal organisms during collection Periurethral area cleaned with mild soap and rinsed Specimen collected in sterile container Bedpans and urinals should not be used Timing Urine should remain in bladder as long as possible urine is good growth medium Number of colony-forming unit (CFU)/ml increases with incubation First morning specimen Acceptable Specimens Clean-catch midstream Straight catheter Indwelling catheter Suprapubic aspirates Cystoscopy specimens Clean-Catch Midstream Periurethral area cleaned Patient begins voiding Collects midstream specimen Fist urine passed not collected avoid NF from urethra Straight Catheter In/out catheter urine Periurethral cleaned Catheter inserted in bladder Midstream specimen collected Indwelling Catheter Clean catheter collection port with alcohol Aspirate specimen with needle and syringe Should not be collected from catheter bag Suprapubic Aspirates Needle inserted through abdominal wall into full bladder Suitable for anaerobic bacteria Cystoscopy Specimens Collected by cystosope Urine from bladder and/or ureter Transport Transported at RT Cultured within 2 hours of collection If not, urine should be refrigerated Preservatives prolong RT transport time to 24 hours boric acid maintains original colony count Unacceptable Specimens Urine catheter tips (Foley catheters) Pooled 24-hour urine Unrefrigerated or unpreserved urine (if older than 2 hours) Urine other than suprapubic aspirates for anaerobic culture Urine Sediment Examination Urinalysis usually includes a microscopic aliquot centrifuged wet mount of sediment examined for WBC and bacteria, indicative of UTI Chemical Methods Included with a Urinalysis, can be done separately for UTI screen leukocyte esterase test nitrate test  leukocyte esterase test Enzyme present in WBC Dipstick Positive → pyuria Nitrite Test Nitrate normal in urine (not nitrite) Some organisms reduce nitrate nitrite Dipstick detects nitrite in urine Positive: significant bacteriuria False negative: some organism can not reduce nitrate (enterococci) False positive: specimen not properly preserved, contamination from nitrate reducing organism Culture Media BAP Enteric agar (MAC, EMB) Other in special situations CHOC if Haemophilus suspected Inoculation Cultured quantitatively on BAP agar CFU/ml is important diagnostic tool Calibrated loops that delivers 0.001 or 0.01 ml of urine Loops dipped into well-mixed uncentrifuged urine loop completely covered Streaked down center of plate and then spread over surface of agar Loops Streaking Incubation Overnight at 35 0 C Colony Count CFU/mL calculated if 0.01 mL loop used number of colonies on plate x 100 = CFU/mL if 0.001 mL loop used (not recommended) number of colonies on plate x 1000 = CFU/mL Colony Count Urine Culture Workup Factors type of specimen (voided, catherized) patient history and symptoms Voided specimens may be contaminated with NF colony count number of colony types present determining what colony is the pathogen General Guidelines: CCMS One or two organisms, >104 CFU/ml ID and sensitivity to be performed One organism, >103 CFU/ml, symptomatic ID and sensitivity to be performed >3 organisms, no predominant type contaminated specimen, reject request new specimen General Guidelines Suprapubic aspirates ID and sensitivity as appropriate special request - non-routine Catheterized, any count ID and sensitivity No Growth 0-999 CFU/mL present Report No growth at xx hours One Type of Possible Pathogen 100,000 CFU/mL Probable infection ID and sensitivity Two Types of Possible Pathogens Each >10,000 CFU/mL Possible infection ID and sensitivity on both One >10,000 CFU/mL, other 50% Terms Primary bacteremia bacteremia with no other known infected site Secondary bacteremia bacteremia associated with an infected body site Occult bacteremia bacteremia with no known cause with or without symptoms mainly in children Pseudobacteremia false bacteremia contaminated materials are source of organisms in blood culture media Bacteremia Patterns Transient minutes to hours in bloodstream body site with organisms traumatized mucous membrane or skin mild (teeth cleaning), severe (surgery) early stages of some diseases meningitis, osteomyelitis, infectious arthritis Bacteremia Patterns Intermittent organisms periodically released into bloodstream (pneumonia, meningitis) caused by abscess Continuous organism present constantly in bloodstream individuals with infected intravascular sites  Bacteremia Sources Intravascular associated with vascular system infected heart valves, catheters, veins Extravascular outside vascular system lymphatic vessels carry organisms to bloodstream UT, RT, abscesses Intravascular Bacteremia Endocarditis – infection of endocardium Viridans streptococci (normal oral flora) Enterococci Catheter, VP shunt associated bacteremia Coagulase negative staph (S. epidermidis) S. aureus Corynebacterium all normal skin flora Extravascular Bacteremia Seed from localized site of infection Meninges N. meningitidis, H. influenzae type B, S. pneumoniae Other sites Enterics: E. coli, Klebsiella, Salmonella Anaerobes: Bacteroides, Clostridium NFGNR: Pseudomonas Other GNR Detection of Bacteremia Mortality rates high prompt detection and recovery of organisms Obtain blood via aseptic venipuncture Blood culture Once growth detected Isolate, identify, and test for susceptibilities  Most Common Causes of Nosocomial Bacteremia Coagulase negative staphylococci S. ~50% aureus Enterococcus spp. Candida albicans Enterics E. coli, K. pneumoniae, Enterobacter spp., Serratia spp. Nonfermenting GNR P. aeruginosa, A. baumannii Collection Sites Venipuncture Peripheral aseptic venipuncture Indwelling intravascular catheters not recommended - contamination used if it is only way to collect blood or patient evaluated for catheter-related bacteremia Collection Methods Needle & syringe Syringe collection (preferred method) transfer into blood culture bottles using same needle Can use butterfly Tube method – lysis centrifugation system Collection Procedure Specimen container preparation Site preparation Specimen collection Site care Specimen Container Preparation Disinfect tops of culture bottles and tubes with 70% alcohol or iodine Site Preparation To avoid contamination with NF some NF can cause significant diseases Clean skin with alcohol to remove debris and oil Skin swabbed with iodine from inside out in concentric circles Allow iodine to dry at least 1 minute to ensure proper disinfection Specimen Collection Venipuncture Blood collected in syringe Blood from syringe must immediately be inoculated into blood culture bottles Invert bottles Mix blood with broth media and anticoagulant Site Care Iodine can cause skin irritation Should be removed with alcohol Specimen Collection Difficult to recover organisms in clotted specimens Anticoagulants Sodium polyanethol Sulfonate (SPS) recommended Inappropriate anticoagulants Citrate, heparin, oxalate, EDTA Toxic to some organisms Sodium Polyanethol Sulfonate Prevents clotting Inhibits phagocytosis Inactivates complement Neutralizes some antimicrobial agents Inhibits some organisms N. gonorrhoeae N. meningitidis Sodium Polyanethol Sulfonate 0.025% concentration in blood culture media Minimize its antibacterial effects SPS blood collection tubes available but not recommended NOTE Blood collected from one venipuncture is considered ONE blood culture Even if blood is divided into several tubes Blood Volume Larger volume = more likely to be positive Recommended amount varies with patient age children have high level of bacteremia children: 100-1000 organisms/mL adults: 1 ml CSF→ centrifuge sediment for smear and culture Gram stain smears sensitivity 75-90% Thick smears Cultures Media BAP, CHOC most common MAC or EMB if GNR seen in gram stained smears anaBAP if requested anaerobes rarely isolated incubate at 35-37 C in CO2 Antigen Detection Tests Available for group B streptococci, Hib, meningococci, pneumococci Should supplement, not replace, smears and cultures Other Types of Meningitis Spirochetes T. palladum and B. burgdorferi Viral Aseptic meningitis No growth from bacterial culture Mycobacterial M. tuberculosis Other Types of Meningitis Fungal Rarely Chronic meningitis Immunocompromised Parasitic Rarely CSF Findings Organisms Cells Dx Bacterial Usually Neutrophils Ag, culture Fungal Occasional Lymphs Stain, Ag TB Rare Lymphs PCR, stain Syphilitic No Lymphs VDRL Viral No Lymphs Serology, PCR Serology, Parasitic Rare Lymphs/Eos biopsy Brain Abscesses Caused by NF organisms anaerobic bacteria, staphylococci, viridans, other streptococci Aspirate and biopsy materials Transported in anaerobic conditions Examined microscopically Cultured aerobically and anaerobically Encephalitis/ Meningoencephalitis Viruses Most common Bacteria L. monocytogenes, Rickettsia, Mycoplasma, B. burgdorferi Parasites Naegleria, Acanthamoeba Reporting Results Critical values Immediate notification Verbal communication followed by written report Gastrointestinal Tract Chapter 34 Introduction Esophagus Stomach Small intestines duodenum, jejunum, ileum Large intestines cecum, colon, rectum Anus Introduction Terms Gastritis inflammation of stomach Gastroenteritis inflammation of stomach and intestines Enterocolitis inflammation of small and large intestines Terms Diarrhea abnormal increase in number of bowl movement loose to liquid stool Dysentery diarrhea with cramping abdominal pain Proctitis inflammation of rectal mucosa N. gonorrhoeae, C. trachomatis, T. pallidum Normal Flora 80% of the dry weight of feces is bacteria Normal flora prevents colonization of pathogens anaerobic bacilli (Bacteroides spp.) GN enteric bacilli Enterococci Streptococci S. aureus Yeast (Candida) Non-Inflammatory Diarrhea Bacterial toxin or enterotoxin Results in outpouring of electrolytes and fluid or watery stool Afebrile with watery, large-volume stool NO PMN, blood, mucous Non-Inflammatory Diarrhea V. cholerae Enterotoxigenic E. coli Bacteroides spp. Viruses Giardia lamblia Cyclospora Cryptosporidium Inflammatory Diarrhea Organisms invade intestinal mucosa Cytotoxins destroy intestinal cells (raw) Fever with loose, small-volume stool Fecal specimen contain PMN, blood, mucous  Inflammatory Diarrhea Salmonella spp. Shigella spp. Y. enterocolitica Campylobacter spp. Enteroinvasive E. coli Clostridium difficile Enterotoxin-Mediated Diarrhea Ingestion of food containing toxin Rapid onset (