UTI, Genital Tract Infections, GI Tract, Public Health Flashcards
What is the CFU/ml calculation for the 0.01 ml loop (10 ul)?
CFU x 100
Bacteremia = > 10^5 CFU/mL
What is the CFU/ml calculation for the 0.001 ml loop (1 ul)?
CFU x 1000
Bacteremia = > 10^5 CFU/mL
Ascending Transmission (UTI)
Organisms multiply in bladder —> ureters and kidneys (goes upwards = ascending)
Common in women
Hospital-acquired UTI in both sexes
Hematogenous (descending) Transmission (UTI)
From bacteremia, bloodborne
Descends down to kidneys and urethra
Urethritis
Infection of the urethra
Asymptomatic bacteriuria
Isolation of bacteria without sign of infection
In elderly people, treat with antibiotics even if asymptomatic
Cystitis
Infection of the bladder
Cystitis
Infection of the bladder
Acute urethral syndrome
Primarily in young, sexually active women
Symptomatic (burning, frequent urination), few isolated organisms
Pyelonephritis
Inflammation of kidney parenchyma, calices and pelvis
Urine Collection Methods
- Clean-catch midstream urine: least invasive
- Straight catheterized urine: uncontaminated
- Indwelling catheter collection: may have contamination like clean catch, collected from catheter port (not collection bag)
- Suprapubic aspiration: needle goes straight into bladder, uncontaminated
Boric acid
Preservative for urine
Do not refrigerate, otherwise urine can form crystals
Up to 48 hrs, but analysis should not exceed 24 hrs
Urine Screening (what you might see if there is infection)
- Pyuria (presence of PMNs/neutrophils) - >400,000 = infection
- Leukocyte count - >=10/mm^3 = infection
- Symptomatic women with pyuria without bacteriuria: UTI with <10^5 CFU/ml or have C. trachomatis, U. urealyticum
- Nitrate (+)
- Leukocyte esterate (+)
- Catalase (+), except strep and entero
Media for Urine
- SBA/MAC
- Columbia colistic-nalidixic (CNA) or PEA: detect G(+) enterics (in case there is G(-) overgrowth — helps isolate)
Counts for UTI detection if there’s a single isolate
> 100,000 CFU/ml - significant bacteriuria — probably UTI
10,000-100,000 CFU/ml - possible UTI
<10,000 CFU/ml - do not work up, likely contaminant
If the same organism is seen on repeat urine cultures, likely a pathogen even if colony counts are low
What do you do for 1 isolate? 2? 3?
1 isolate: work up
2 isolates: usually work up, 1 might be contamination
3 isolates: likely contamination
UTI in kids
Bacteria is more common in boys than girls - circumcision can help keep area clean
Preschool girls (and up) develop more UTIs
May be asymptomatic
Acute, uncomplicated UTI in women
Immediate symptoms
Dysuria, urgency, frequency, suprapubic pain
Less bacteria in urine because infection just started >10 WBC/mm^3 or >10^3 CFU/ml
Acute, uncomplicated pyelonephritis
Involves kidneys
Fever, chills, flank pain
More bacteria - >10^4 CFU/ml
Uncomplicated UTIs
Occur in healthy women and men, responds well to antibiotics
Complicated UTIs
Occurs in both sexes
More difficult to treat, greater morbidity and mortality
Normal Flora of Urethra
Coag (-) staph (except S. saprophyticus)
Viridans and nonhemolytic strep
Lactobacilli
Diphtheroids
Nonpathogenic Neisseria in females
Anaerobic cocci
Anaerobic G(-) rod
Propionibacterium sp.
Commensal Mycobacterium sp.
Commensal Mycoplasma sp.
Female genital tract - in prepubescent and postmenopausal women
Staph and Corynebacteria
Is GBS common in elderly population?
Yes, work up if <50 yo. Otherwise, it’s normal
Common STD agents
C. trachomatis
N. gonorrhoeae
Trichomonas vaginalis
HIV
Ureaplasma urealyticum
Mycoplasma hominis
Adenovirus
Coxsackievirus
Molluscum contagiosum (poxvirus)
HPVs
Anorectic lesion
Inflammation of anal muscle
May cause proctitis
Vaginitis
Symptoms: abnormal discharge, offensive odor, itching
Agents:
- Candida albicans - 80-90% of cases, thick and cheese discharge
- Trichomonas vaginalis: slightly offensive, yellow-green discharge. Dies quickly so process immediately
- Gardnerella vaginalis: BV, polymicrobic (caused by many organisms, possibly the result of loss of lactobacilli). Clue Cells
Cervicitis
Symptoms: Increased PMNs in endocervix, purulent discharge (pus)
Agents: N. gonorrheae, C. trachomatis, HSV, HPV
Pelvic Inflammatory Disease (PID)
Cervical microorganisms travel to endometrium, fallopian tubes, other pelvic structure
May produce endometritis, salpingitis (inflammation of fallopian tubes), peritonitis (inflammation of abdomen lining), abscesses. Can cause scarring of fallopian tubes or infertility if left untreated
Agents: N. gonorrhoeae, C. trachomatis, anaerobes, G(-) rods, strep, mycoplasmas
Infections after gynecologic surgery
Cellulitis, abscesses
Agents: Aerobic G(+) cocci, G(-) rods, anaerobes, Mycoplasmas
Infections with pregnancy
Spread hematogenously (from blood) to upper tract
Transplacental Prenatal Infection Agents
Through placenta
Bacteria: Listeria monocytogenes, T. pallidum, Borrelia burgdorferi
Viruses: Cytomegalovirus (CMV), rubella, HIV, parvovirus B19, enteroviruses
Parasites: Toxoplasma gondii, Plasmodium sp.
Ascending Prenatal Infection Agents
During delivery
Bacteria: GBS, E. coli, L. monocytogenes, C. trachomatis, genital mycoplasmas
Viruses: CMV, HSV
Natal Infections Agents (passing through birth canal)
Similar to Ascending Prenatal Agents
Bacteria: GBS, E. coli, L. monocytogenes, N. gonorrhoeae, C. trachomatis
Viruses: CMV, HSV, enteroviruses, hepatitis B virus, HIV
Postnatal Infection Agents
Route of infection: transplacental, ascending, passing through birth canal, from nursery, environment, breastfeeding, etc.
Agents: all agents from prenatal and natal infections
Orchitis
Inflammation of testicles
Typically acquired by bloodborne dissemination of viruses
Prostatitis
Enlarged prostate gland - gets bigger naturally as men age
Lower back, lower abdominal pain, urinary discomfort ejaculatory complains
Syphilis
T. pallidum
Nontreponemal serological tests
VRDL (cardiolipin antigen) and RPR
non-specific reagin test
Specific treponemal test
Antibody against antigen of the organisms
FTA-ABS, TP-PA, EIAs, MHA-TP
Chlamydia
C. trachomatis
Non-gonococcal urethritis - most common STD in US
Symptoms: asymptomatic in 50% males, 70-80% females
Can cause: cervicitis, bartholinitis, proctitis, salpingitis, epididymitis, acute urethral syndrome, PID, lymphogranuloma venereum (small lesion on genital area)
Similar to gonorrhea
Gonorrhea
N. gonorrhoeae
Symptoms: occur 2-5 days after infection in women, up to 1 month in men
Intracellular G(-) diplococci
Extracellular G(-) diplococci in women = normal flora
Trichomoniasis
Trichomonas vaginalis - flagellated protozoan
Transmission: direct contact with contaminated clothing or towels
Trophozoite
Symptoms: purulent discharge, itchy skin/vulval pruritus, odor, edema, erythema
25-50% asymptomatic women, fewer in males
Diagnosis: wet mount, Giemsa/papanicolaou smear, culture, antigen detection, PCR
Specimen Transport (for gonococci or chlamydia/mycoplasmas)
Gonococci: swab in modified Stuart’s or Amie’s charcoal media, room temp
Chlamydia/mycoplasma: swab in media with antibiotics, on ice
3 major causes on BV
G. vaginalis
Candida sp.
T. vaginalis
Detected by hybridization assay
Does the upper small intestine or distal ileum have a higher count of resident flora?
Distal ileum
Invasive infection
Has leukocytes
Toxic infection
No leukocytes
Gastroenteritis
Syndrome with symptoms of n/v/d and abdominal discomfort
Dysentery
Inflammatory disorder of GI tract
Usually has blood and pus in feces with pain, fever, abdominal cramps
Resulting from large intestine disease
Enterocolitis
Inflammation of mucosa of small and large intestines
Toxin Production - Enterotoxin
Causes gastroenteritis in intestines
Ex. of microorganisms: Vibrio, Shigella dysenteriae, ETEC, Salmonella, C. difficile, Aeromonas, Campylobacter jejuni
Toxin Production - Cytotoxin
Causes destruction of cells
Ex. of microorganisms: Shigella sp., C. difficile, EHEC
Toxin Production - Neurotoxin
Causes paralysis
C. botulinum, S. aureus, B. cereus
Microorganisms with Attachment within or close to mucosal cells/adherence
EPEC, EHEC, Cryptosporidium parvum, Isopora belli, Rotavirus, Hep A/B/C, Norwalk virus
Pathogenic Mechanism - Invasion
Invade epithelial
Shigella, EIEC, Campylobacter jejuni, Plesiomonas shigelloides, Yersinia enterocolitica, Edwardsiella tarda, etc.
Enterotoxin-Mediated Diarrhea
Symptoms:
- Rapid onset of diarrhea, <12 hrs
- Lack of fever (not invasive) - no wbcs to help with infection
- Absence of blood or pus
- Large number of watery stools
Food Poisoning Agents
S. aureus, B. cereus, Type A Clostridium perfringens, Clostridium botulinum
Norwalk virus (Norovirus)
From shellfish and salads
Cruise ship diarrhea
Why do we not accept cultures from inpatients after they’re hospitalized for 3 days if suspected bacterial cause of diarrhea?
Diarrhea is likely from antibiotic usage - C. difficile
Virus (stool) transportation
Fresh stool in container, no preservatives, keep refrigerated
Parasite (stool) transportation - O&P
Stools in preservative within half an hour of collection
Collect 3 samples over 3-9 days
Media for C. difficile
CCFA
CDSA
Pseudomembranous colitis
C. difficile
Acceptable additive for urine
Boric acid
V. vulnificus vs.
V. cholerae vs.
Yersinia enterocolitica
V. cholerae - yellow on TCBS (ferments sucrose). Rice water stools
V. vulnificus - green on TCBS. Ferments lactose while all others are non-lactose fermenters
- Raw tilapia, liver disease
Vibrios - 6.5% NaCl growth or fresh water, grows better in summer (20°C), O/129 Test (S)
Y. enterocolitica - bullseye on CIN, urease (+)
Criteria for accepting stools for culture
Preservative (for bacteria, no preservative for viruses)
Refrigerated if not inoculated within 2 hrs of collection
Vaginal flora changes with age
Lactobacilli is predominant
Prepubescent and postmenopausal women - Staph and Corynebacteria
Reproductive age women - facultative anerobes
Some women carry GBS - also popular in elderly population, normal if >50. Work up and report if <50 yo
Trichomonas vaginalis culture media
Diamond’s medium or plastic envelopes with inoculum
Urogenital specimen collection
Swab in sterile saline (T. vaginalis, different swab for gonococci, chlamydiae, ureaplasma)
Aspiration with syringe for Batholin gland exudate (not swab)
Gonococci swab transport
Modified Stuart’s or Amie’s charcoal media in RT
Chlamydia or mycoplasma specimen transport
Media with antibiotics, on ice or stored at 4°C
Whiff test
BV diagnosis
Fishy odor
Indicates decrease in Lactobacillis and gold standard (Clue cells)
Pathogens with virulence factors for UTIs
- Uropathogenic E. coli
- Proteus sp.
- S. saprophyticus
Adherence
Esophagitis
painful, difficulty swallowing, patients with underlying diseases (HIV)
Candida, HSB, CMV
Gastritis (stomach ulcers)
Inflammation of gastric mucosa
H. pylori - urease (+)
Proctitis
Inflammation of rectum
STIs
EHEC/O157:H7
Bloody (hemorrhagic), watery diarrhea, abdominal cramps
Low-grade or no fever
No leukocytes in stools
Pink colonies (shiga toxin producing) on chromagar
MUG (-), SMAC (-)
Shigella sp.
Highly infectious
Dysentery - often bloody diarrhea
High fever, chills, abdominal cramps, pain with tesnesmus (feels like having to go but no stools)
Salmonella sp.
n/v/watery d, fever, chills, abdominal pain
Self-limiting
Campylobacter sp.
Gull wing, G(-)
Self-limiting
Modified Skirrow’s, Campy blood agar, 42°C
Clostridium difficile
Pseudomembranous colitis - from antibiotic use
Culture on CCFA or CDSA
Toxin production for diagnosis of C. difficile (vs just antigen (+)
Rabies
Virus that infects CNS
Bats/dead wild animals
Lyme Disease
Borrelia burgdorferi
Bulls eye rash, fever, fatigue, can spread to joints, heart CNS
Francisella tularensis
Contact, ingestion of contaminated food/water, inhalation
Hunters and outdoor enthusiasts are more likely to get infected
Market men’s disease, water trapper’s disease, Ohara’s fever, rabbit fever, deer-fly fever
Rabbit = most common mammal associated
Small G(-) coccobacilli
Beta-lactamase (+)
Grows on Cysteine enriched media (thio, cysteine-heart agar, TM, chocolate, BCYE)
Slow grower
Oxidase (-)
Catalase weak +/-
Brucella sp.
Break in skin, ingestion of unpasteurized milk, inhalation
Malaise, night sweats, fever, chills, can relapse
Highly infectious, do not sniff
B. melitensis, B. suis are more infectious than B. abortus
Small, G(-) coccobacilli
Catalase (+)
Oxidase (+)
Non-motile
Bacillus anthracis
Large G(+) boxcar
Medusa Head, ground glass colonies
Non-hemolytic
Non-motile
Catalase (+)
Woolsorter’s Disease
