Control Infection

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WASH

• Control Infection

Prevent Infection !
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Microbiology for ICPs

• Robert Berg, CIC, MT(ASCP), MBA
• CLS Microbiologist from 1975
• Lab Manager from 1982
• MBA 1997
• Infection Control from 2000
• CIC in 2002

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Objectives

• The participant will be able to
• describe the reliability of sputum culture
  results by using the gram stain
• describe the Factors that can adversely affect
  reliable Micro results
• compare viral vs bacterial Meningitis
• describe the laboratory markers for HBV, HAV,
  and HCV

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Definitions

• WBC white blood cells
• PMN polymorphonuclear leukocytes
• Polys polymorphonuclear leukocytes
• Segs segmented neutrophils
• Neuts segmented neutrophils
• Lymphs/mononuclears lymphocytes

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Clinical Microbiology

• Clinical Goal
• Whats growing
• What antibiotic can I use (either by
  predictive value of the bug name or by Sensi
  result)
• Epi Surveillance Goal
• Give me the full name and Sensi pattern so I can
  determine if I have a cluster or not

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Robs Rule of Thumb 1

• Laboratory Tests Not 100
• Interpret all results accordingly !!
• (include clinical conditions in interpretation)

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Robs Rule of Thumb 2

• Just because a bug is growing does not mean its
  causing diseasecolonized??
• For normally sterile body sites, this indeed may
  be an infection
• Interpret all cultures knowing what would
  typically/normally grow in that site

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Variables to Reliable ResultsPre-Analytical
Factors

• Specimen Collection
• Proper site selected for collection
• Proper collection technique/method
• Swab, needle/syringe, sterile collection, etc
• Collected onto correct swab and transported on
  correct media
• Sterile container needed (sputum, stool, fluids,
  etc)
• Specimen Transport
• Temperature
• Time

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Variables to Reliable ResultsPre-Analytical
Factors

• Time delay in set-up onto media and into
  incubator
• Correct media (type and freshness, was it stored
  correctly)

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Variables to Reliable ResultsAnalytical Factors

• Quality of media
• Incubator temp, humidity, CO2 level
• Length of time of incubation
• Technology used by lab (instrumentation)
• Skill of Micro Staff

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Variables to Reliable ResultsPost-Analytical
Factors

• Computerization
• Prompt and accurate printing of results
• Time it takes results to get to the chart
• Accurate interpretation of results by Doc
• Time it takes physician to review and act on
  results

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Inoculate MIC/ID plates and put into incubator
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Put into analyzer to read reactions
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Gram Negatives Can be Hard to See
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Gram Stains

• Helpful in guiding initial empiric therapy
• Helpful in evaluating quality of culture result
• Does not improve patient outcome if the results
  dont get to the physician ASAP

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Sputum Gram Stains Include

• SEC (squamous epithelial cells)
• WBC
• Bacteria

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Sputum Gram Stain ScreenSEC

• lt10/lpf excellent specimen, no appreciable oral
  contamination
• 10-25/lfp equivocal, but accept the spec.
• gt25/lpf reject due to unacceptable levels of
  oral contamination

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Sputum Gram Stain ScreenWBC

• lt10/lpf no infection
• Or not much of a response due to
  immunosuppression, PCP, Mycoplasma, viral, etc)
• 10-25/lpf equivocal
• gt25/lpf infection is evident (Purulent)

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Sputum Gram Stain Mixed oropharynx flora

• Gram neg rods
• Small hemophilus
• Gram pos cocci
• Clusters staph
• Short chains strep, GBS, others
• Long chains strep, GAS, others
• Gram pos rods
• Diphtheroids
• Lactobacillus
• Yeast

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Lower Respiratory Cultures

• Sputum BW often contaminated with oral flora
• Protected brush not contaminated with oral
  flora recommended to do a semi-quantitative
  method put brush into 1.0mL TSI broth vortex
  inoculate agar with urine loop reported as
  number of CFU/ml
• Tracheal aspirates often shows colonizers

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Lower Respiratory CulturesCommon Pathogens

• Strep pneumo primarily CAP uncommon as HAP
  aminoglycosides can select for S. pneumo
• H. flu primarily CAP
• Moraxella (Branhamella) catarhallis most often
  CAP, but can be hospital acquired
• Staph aureus CAP and hosp acquired must be
  recognized quickly ?mortality

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Lower Respiratory CulturesCommon Pathogens

• Pseudo aerugenosa often vent or ICU related
• Mycoplasma CAP
• Steno maltophilia Vent or ICU related
• Yeast not usually the infecting organism unless
  it is ?70 of all the organisms present and oral
  contamination can be ruled out

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Lower Respiratory Cultures

• Aspiration pna
• Can expect mix of organisms including anaerobes
• Cover with clinda gent
• Water-borne organisms commonly implicated in
  nosocomial pna PSA, K. pneumo, Acinitobacter, S.
  maltophilia, Enterobacter

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CSF Cultures

• Source often from URI flora
• Meningitis due to GNR or Staph usually due to
  predisposing factors such as trauma
• Adult Strep pneumo (gram pos cocci in
  pairsneed to know if in pairs, clusters, chains.
  
• Strep pneumo generates ?WBC response

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Onset of Symptoms Person presents to MD for
medical evaluation and Lumbar Puncture (LP)
Bacterial Viral
Cloudy Clear Elevated
Protein Normal or Elevated Protein Decreased
Glucose Normal Glucose WBC Positive
Neutrophils Presence of organisms
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Viral vs Bacterial

• Relatively common but rarely serious
• Recovery is usually complete (West Nile?)
• Active illness seldom exceeds 10 days
• Rash is usually not present
• Enteroviruses, Echoviruses, Coxsackieviruses,
  Arboviruses
• Half or more of cases have no cause identified

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Precautions

• Droplet Precautions for the first 24 hours after
  effective antibiotic therapy
• Routine cleaning agents and disinfection
  practices
• Viral Fecal-Oral transmission

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Robs Observations

• Bacterial ?Glucose ?Protein
• Viral ?Glucose ?Protein
• (Or equivocal)
• Strep pneumo lots/lots of WBC
• H. flu and Meningococcus can be hard to see in
  gram stain

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Meningococcal Disease
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Parini, Sue, RN, CIC, BS, MA. Nursing
Management, Aug 2002. The Meningitis
Mind-bender
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CSF Case
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CSF Case
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CSF Case
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S-SSI

• Not usually anaerobes
• Generally skin flora but not necessarily so
• Can also be gnr

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D-SSI O-SSI

• Consider anaerobes and aerobes
• Anaerobic examples
• B. frag
• Clostridium
• Peptostreptococcus
• Propionibacterium (septic arthritis,
  endocarditis, suture sites for craniotimy)
• Aerobic Examples
• Staph
• Strep
• GNR

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Blood Cultures

• Two bottles per draw (aerobic anaerobic)
• Bacteremia in Adults small numbers (?30/mL) of
  bacteria ? gram stain false negative (except in
  neonates)
• Can be monomicrobic
• or polymicrobic (any intra-abdominal event eg
  ruptured appx, bowel surgery, intestinal
  perforation)

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Blood CulturesTiming of the Draws

• No need to coordinate blood draws with fever
  spiking.
• Best chance of getting positive culture is 2.5
  hrs to 30 min prior to fever spike.
• Mayo Clinic determined that in most cases, 3 sets
  are sufficient. Other sources suggest that for
  endocarditis, 2 sets yield 95 efficiency. 3
  sets do not yield significantly more value
• Never obtain only one set of BC

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Blood CulturesTiming of the Draws

• To R/O bacteremia
• pt mildly febrile 2-3 BC collected at 15 min to
  1 hr intervals
• Patient critically septic
• overriding concern is to get abx on board ASAP
  ? 2 BC taken one right after the other,
  different sites, is recommended
• Dont let clerical needs delay the collection of
  the BC nor let it delay initiation of abx

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Contaminants???

• Coag neg staph
• Diphtheroids
• Bacillus
• Proprionibacteria
• Viridans strep
• Aerococcus
• Micrococcus

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Blood Culture Drawn from Line
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Urine Cultures

• E.coli 80. Proteus, Klebs, Enterobacter,
  Pseudo, Gardnerella
• MRSA, Enterococcus, Staph sapro
• Infection status leukocyte esterase and/or
  nitrite can be helpful
• ?WBC w/ negative cultures may be chlamydia or GC.

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Urine Cultures

• Colony count not always reliable indicator of
  infection (due to collection and transport
  issues, hydration status of patient, etc).
• RT colony count doubles every 20 min
• Max 2 hr at RT
• Max 24 hr at 2-8?C

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Bowel Flora

• Normal mix of bacterial flora keeps numbers of
  yeast, C.diff, and other potential pathogens in
  check
• With altered flora
• yeast can proliferate
• C. diff can proliferate
• Pseudomonas can proliferate
• VRE can proliferate
• Etc, etc, etc

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ESBL

• Cephalosporins were developed to combat emergence
  of ?-Lactamase producing GNR
• Soon, there was Resistance to 3rd generation
  Cephalosporins (eg cefotaxime, ceftazidime,
  ceftriaxone) and Monobactams (eg aztreonam)
• Sensitive to Cephamycins (cefoxitin, cefotetan,
  cefmetazole) and carbapenems (eg meropenem,
  imipenem)

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ESBL

• Drug of choice for ESBL Carbapenems (mero,
  dori, imi, erta)
• Carbapenemase breaks down all Penicillins,
  Cephalosporins, Carbapenems
• Carbapenems the last resort for gram negative
  infections. Most potent ß-lactam class against
  almost all Enterobacteriaceae
• Carbapenemase-resistant Enterobacteriaceae

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Antibiotics Associated with CDI
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When Micro Dept Reports

• Mixed oropharynx flora
• Mixed fecal flora
• Mixed vaginal flora
• Mixed skin flora

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What Would You Do With Unfamiliar Organisms ??

• Gymnoascaceae imperfecti
• Strep bovis

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Hepatitis
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Hepatitis

• HAV
• HAV, total current or past HAV
• HAV, IgM definitive dx of current HAV infection
• HBV
• HbsAg current or chronic HBV
• HbsAb recovery or immunity to HBV
• Anti-Hbc current or previous HBV infection
• Anti-Hbc IgM recent acute infection. If also
  HbsAg ? then its current acute infection.
  Distinguishes Acute vs Chronic infection

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Hepatitis C

• Anti-HCV
• Presence of antibodies to the virus, indicating
  exposure to HCV. Active vs Chronic vs
  Resolved???  
• HCV RIBA
• Confirmatory test of antibodies to the
  virustells if HCV was true positive (present or
  past is unanswered)

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Hepatitis C

• HCV-RNA
• Positive result Active Infection. Also used
  for test of cure.
• Viral Load HCV
• Measure the number of viral RNA particles in
  blood. Viral load tests used before and during
  treatment to help determine response to treatment
   

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Hepatitis C

• Viral genotyping
• Used to determine the HCV genotype
• There are 6 major types of HCV the most common
  (genotype 1) is less likely to respond to
  treatment than genotypes 2 or 3 and usually
  requires longer therapy (48 weeks, versus 24
  weeks for genotype 2 or 3). Genotyping is often
  ordered before treatment is started to give an
  idea of the likelihood of success and how long
  treatment may be needed.

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Case 1

• ETT sputum collected upon admission
• Gram Stain
• gt25 wbc/lpf, lt10 sec/lpf
• 3 gram pos rods (these were really gram pos
  cocci in pairs)
• Results Strep pneumo, PCN-susceptible
• Comment on this report

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Case 1 discussion

• Probably erroneous gram stain this could have
  misled the doctor in initial tx
• CAP
• PCN ok to use

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Case 2

• Expectorated Sputum
• Gram Stain
• gt25 wbc/lpf
• gt25 sec/lpf
• 3 mixed flora
• Culture
• 3 mixed oropharynx flora
• What conclusions can be drawn?
• What if the bacteria turned out to be MRSA rather
  than 3 mixed flora

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Case 3

• Source Peritoneal Absc/Perirectal Absc
• Results Strep anginosus group
• E. coli
• Citrobacter freundii
• B. frag

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Case 4Wound, superficial, toe

• Results 3 diphtheroids
• 2 B. frag
• 3 Klebs oxytoca
• 3 Alcaligenes spp
• 3 Staph aureus
• 3 Enterococcus faecium
• This is typical picture of Diabetic Foot Ulcer

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Case 5

• Source Wound, foot
• Gram stain 1 WBC
• 2 gnr
• 2 gpr
• Results Proteus mirabilis
• What were the gpr?? Why werent they recovered??

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Case 6

• Growth of organism isolated from broth subculture
  only

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• Lets Discuss Your Cases??
• Questions??