The most common device associated infections VAP CAUTI CR-BSI

The most common device associated infections VAP CAUTI CR-BSI

Laboratory confirmed ventilatorassociated pneumonia Ventilated patient had a chest radiograph which showed new or progressive infiltrates, consolidation, cavitation or pleural effusion

and at least one of the following criteria: New onset of purulent sputum or change in character of sputum; Organism cultured from blood; Or from endotracheal aspirate specimen, bronchial brushing or BAL, or biopsy

Sample collection: Endotracheally suctioned specimens are acceptable in patients who had been intubated for no more than 24 h Otherwise, obtaine specimen either with non bronchoscopic or bronchoscopic BAL

Non bronchoscopic BAL Performed using telescoping catheter. Insert the catheter into an endotracheal tube. Inject 30 ml sterile saline solution. Apply suction and collect at least 20 ml fluid in the specimen trap.

Bronchoscopic BAL The fiber optic bronchoscope is advanced down the endotracheal tube. Lavage the segment with saline solution Aspirate the fluid through the bronchoscope and obtain BAL fluid for cultures. A threshold of > 10 4 cfu/ml was defined as a significant infection

EA EA samples should be obtained by sterile means using a suction catheter and collected in a sputum trap. Delivery: within 2 h to the microbiology laboratory

Classification and solubilization of EA Note the quantity. Categorize the quality as: serous, mucous, sanguineous or purulent. Add equal volume of sterile sputolysin Vortex the mixture for 2 min.

Screening ETA Specimens Based on the number of squamous epithelial cells (SEC) observed at a magnification of 10X (low power field [lpfl). large numbers of SEC means contamination with upper tract secretions Cutoff point for rejecting specimens: >25 SEC/lpf.

Microscopy of EA Stain by Gram s and Giemsa s Semiquantitative grading of PMN Grade + ++ +++ No. PMN/HPF 0-10 11-20 >20

Quantitative EA culture Prepare1/10, 1/100, and 1/1000 and extra dilutions of homogenized EA in sterile saline. Plate 0.01 ml aliquots onto: 5% blood, chocolate, MacConkey agar and SDA. Incubate cultures at 37 C aerobically except for the chocolate agar cultures which are incubated in CO 2 enriched atmosphere

Evaluate for growth at 24 and 48 h SDA plates are retained for 7days. Count colonies and identify bacteria. Detection limit:10 5 CFU/ml. CFUs per ml are calculated by multiplying number of colonies x dilution factor x inoculation factor.

Viridans streptococci, Corynebacteria spp. and coagulase-negative staphylococci (CNS) are regarded as contaminants unless the same species isolated on two consecutive days in concentrations of >10 5 cfu/ml.

Rejection Criteria for EA 1. >25 SEC/ lpf 2. No organisms seen at oil immersion magnification. 3. The finding of yeast only: these specimens grew Candida species, which are colonizers of the oropharynx or endotracheal tubes. Cryptococcus neoformans and the dimorphic fungi do not cause VAP.

Nasogastric tube Serious risk factor for aspiration pneumonia Sampling of nasogastric tubes Gastric aspirates Drawn after an overnight fast (12 h) Oropharyngeal cultures should be performed simultaneously Obtained at the time of insertion of a new NGT

Gastric aspirates Obtained by injecting 20 ml of sterile saline followed by aspiration of the gastric contents Plate samples immediately Incubate plates aerobically at 37ºC for 48 h. Only moderate to heavy growth should be considered positive. Corynebacterium spp. and viridans streptococci are considered commensals

Laboratory confirmed CAUTI When a patient with a urinary catheter had one or more of these symptoms with no other recognized cause Fever (temperature > 38 ºC), Suprapubic tenderness With culture positive urine showing > 10 3 CFU per ml, with no more than two microorganisms isolated.

Or when a patient with a urinary catheter had at least two of the following criteria with no other recognized cause +ve dipstick analysis for leucocyte esterase or nitrate, Pyuria (>10 leucocytes per ml of urine) Organisms seen on Gram stain or Physician diagnosis of UTI

Urinary catheter samples kink the tubing 3 inches below the sampling port Disinfect the surface of the sampling port. Using aseptic technique, position the syringe in the center of the sampling port.

Slowly aspirate urine sample into syringe and remove syringe from sample port Unkink tubing Transfer urine specimen into specimen cup or follow hospital protocol Discard syringe according to hospital protocol.

Refer the specimen to the lab. Note the method and time of collection and clinical diagnosis. The specimens should be cultured within 2 hours or refrigerated until processed. Foley catheter tips are not suitable for culture.

Specimen rejection: Unlabelled specimens Prolonged transport Duplicate specimens Specimens unsuitable for the request (e.g., foley catheter tips).

Vascular catheter related infections

Contaminated infusate If contaminated infusate is suspected The fluid must be cultured The bag saved for batch number and manufacturer follow-up.

Risk index for assessment of infusion phlebitis severity 0 = No pain at the site, no erythema, swelling, induration or palpable venous cord 1. Pain at the IV site 2. Pain, erythema, possible swelling 3. Pain, erythema, swelling, induration and a palpable venous cord > 7cm above the cannula site

4. Pain, erythema, swelling, induration, palpable venous cord >7cm above the IV site, frank venous thrombosis, which may cause the infusion to stop running 5. Positive blood culture

Diagnosis of superficial CRI Physical examination. Swab from the skin, the catheter hub, or discharge Gram and acid-fast stain Swab cultures from the exit site or from drainage

Systemic catheter-related infection Diagnosis include procedures require catheter removal and those that can be performed with the catheter in place.

The gold standard for diagnosis of CRBSI is quantitative or semiquantitative catheter cultures Semiquantitative (Maki roll-plate) method Is the most widely used Detects only extraluminal infections.

Quantitative method, The most sensitive culture method Allows detection of intraluminal catheter infections

Cut off of positive culture: In semiquantitative culture: >15 CFU of single organism is a positive, while in quantitative culture: >10 3 CFU/ml. The major drawback with these methods is that they require the removal of the catheters.

Catheter-related bacteraemia Positive peripheral blood cultures plus a positive catheter culture involving the same micro-organism. Positive peripheral blood cultures plus isolation of the same micro-organism from the pus in the catheter insertion site

Catheter blood cultures become positive at least 2 h before peripheral blood cultures, with samples collected simultaneously from both sites (with an automated bacterial detection system)

COLLECTION OF CATHETER SEGMENT(S) The intra-cutaneous segment and distal tip The catheter put in a dry sterile container Must not remain at room temperature for more than 4 hours.

A.Cleanse skin around the insertion site B. Using sterile forceps, withdraw the catheter keeping the external portion away from the skin surface. Apply gentle pressure with a dry dressing (not alcohol swab)

C. Procedure varies with the length of the catheter. 1. Shorter catheters (5-7 cm): Using sterile scissors cut the catheter few millimeters inside the skin-catheter- interface. 2. Longer catheters (>16 cm): Two segments (5-7 cm) are obtained. A proximal segment few millimeters inside the skin-catheter-interface The distal tip segment

D. Place each catheter segment in a dry sterile container E. Inspect the catheter exit site and note if any purulence can be expelled. F. If pus can be expelled from the catheter exit site, swab the drainage and send it to the laboratory. G. Send the catheter segment(s) to the laboratory. Label the location and type of IV catheter

Procedure for Semi-Quantitative Cultures of Catheter Segments 1. Aseptically transfer the catheter segment onto the surface of a sheep blood agar plate. 2. Using sterile swab, roll the catheter segment across the plate, back and forth at least 4 times. 3. Incubate aerobically and in CO2 at 37ºC.

Plates are to be held for 48 hours before being discarded as negative. A colony count of 15 is considered a positive culture, whereas a count of <15 colonies suggests contamination

Each colony type that appears on the plate is to be enumerated and identified. All yeast should have germ tubes performed, and should be speciated if 15 colonies. Perform susceptibility test if it was ordered.

RESULT REPORTING 12-24 hours: Report morphotype and count. 15 colonies suggests local canula infection. If <15 colonies, probably not significant. If no growth, report "No growth". 24-48 hours: Add identification and susceptibility result.

Quantitative catheter cultures Using the flush, sonication or vortex techniques Allow identification of microorganisms from both internal and external surfaces Cut-off for the diagnosis of CR1 varies: using sonication ( >10 3 CFU/ml), vortex ( >10 2 CFU/ml).

Flushing Flush of the catheter lumen with 2 ml culture broth Followed by plating of serial dilutions of 0.1 ml of the medium

Vortexing Introduce the segment of catheter in a tube with 1 ml of sterile distilled water Vortex Followed by plating of serial dilutions of 0.1 ml of the medium

Sonication Sonicate to remove adherent microorganisms Culture serial dilutions of 0.1 ml of the suspensions Sonication of catheters followed by cytospin Gram-stain of sonication broth facilitate rapid diagnosis.

Microscopic study Withdrawn catheters are stained by the Gram stain or acridine orange methods The presence of one microorganism per 20 fields is considered to be positive. Rapid methods

They can be performed only on transparent plastic catheters with thin walls. Require experience and are laborious. Less sensitive and specific.

Methods for diagnosis of CRI without catheter removal 1. Obtaining quantitative blood cultures through catheter, and comparing the results with a peripheral blood culture Finding of CFUs/ml of catheter blood that is 5 to 10 times the number found in peripheral blood Quantitative blood culture methods may be performed by pour plating or lysis centrifugation

Pour plate method

2. Both culturing of superficial swabs (skin and hub) and quantitative blood cultures. 3. Quantitative trans-catheter blood culture with > 100 CFU/mL: Withdraw the stopcock, Disinfect the 3 way tap Insert sterile syringe aseptically into the port and withdraw 10 ml blood)

4. Acridine orange leucocyte cytospin (AOLC): Centrifuging blood extracted through the catheter to obtain the leucocytes. Stain of the leukocyte layer on a slide Using acridine orange. Detection of bacteria denote a positive result, then cytospin preparation is Gram stained to characterize the bacteria

5. Endoluminal brush technique: Identify infected CVC in situ. The brush collects fibrin as it is passes in and out of the device. Complex and expensive method Little experience to recommend its use.

6. Estimation of serum levels of anti-lipid S IgG by ELISA Extracellular short chain lipoteichoic acid produced by CoNS Serum levels are significantly higher in patients with systemic CRI

Quantitative culture is the most accurate method for catheter segment culture Unpaired quantitative catheter blood culture is the single most cost-effective test, especially for long-term catheters.