It is usually quite easy for the technologist to identify the arrangement of Gram positive cocci and the report “Gram positive cocci in clusters” strongly suggests a species of Staphylococcus will be identified in the culture.
See Notes-Staphylococci
See Staphylococci Gram stain

The initial evaluation of this finding is a determination of the likelihood that the organism is S. aureus in which case it is a true pathogen or one of the Coagulase negative staphylococci (CNS) in which case it is quite likely to be a skin contaminant.

Lab differentiation of S. aureus and CNS

A tube coagulase test will be performed on a centrifuge-concentrated “pellet” of the microorganisms in the bottle and is usually positive within 2 hours if the organism is S. aureus. The report will be updated to read “S. aureus isolated – presumptive identification”.

If the tube coagulase test is negative for 6 hours and initial growth on the plate is consistent with CNS (often, but not always) a report “Coagulase negative Staphylococcus species isolated – presumptive identification” will be issued.

The pelleted material is also inoculated onto special media that rapidly identifies MRSA. This chromogenic agar may be referred to as a “chrome plate” by laboratory staff. It is commonly positive within 6 hours and if the isolate is coagulase positive (i.e. is S. aureus) the report will be updated to “Staphylococcus aureus MRSA Isolated – presumptive identification”.

Findings suggestive of CNS being a contaminant

The isolate is found in only one culture
This is one of the primary reasons that two different venipunctures are required when performing blood cultures. See Blood Culturing.

If CNS is found in only one culture of multiple the final report will reflect the likelihood of it being a contaminant. “Routine susceptibilities not performed. Culture results may represent contaminants or true pathogens. If clinical relevance is determined consult Microbiology for further workup. Specimen is held for 7 days.”

The clinical scenario does not fit
The majority of true CNS bacteremias are associated with indwelling central venous catheters that have been in place at least several days. Patients with permanent intravascular foreign material are also at risk e.g. prosthetic heart valves, vascular grafts.

Appropriate empiric therapy

For anyone who is acutely unwell and has gram positive cocci in clusters in blood culture, it is prudent to give a dose of vancomycin while waiting for further information. This will cover for the possibility of MRSA and resistant CNS.

The qualification “resembling coliforms” is added if the technologist is confident that the organism viewed is likely to be a member of the family enterobacteriaciae see Gram negative bacilli. E.coli is one of the most common organisms found in blood cultures.

Other coliforms include Klebsiella spp., Serratia spp., Proteus spp., Citrobacter spp., and Enterobacter sp.. The last four genera are sometimes referred to as the “SPICE” group and are distinguished by higher levels of resistance to antibiotics, esp. Beta-Lactam antibiotics. These resistant organisms are more often seen in complicated hospital-associated infections esp. in ICUs.

Sources of coliform bacteremia

The most likely sources of coliform bacteremia discovered in a patient that has presented with an acute condition to hospital are:

• The urinary tract i.e. pyelonephritis or prostatitis as cystitis is not usually associated with bacteremia.

• The biliary tract i.e. ascending cholangitis generally secondary to obstruction by stones or tumors. Simple cholecystitis is less likely to be associated with bacteremia.

• The colon Any process that results in leaking of colon contents provokes abscess formation that can be a source of bacteremia. Common conditions include appendiceal abscess and diverticulitis.

Often, by the time the blood culture is positive, the source is clear by symptoms, signs and other lab tests. Urinalysis and urine cultures may be positive. Abdominal surgery may have already been performed or is planned.

Likely effectiveness of empirical therapy

This is determined by assessing likely source, prior microbiology, local susceptibility patterns and response to therapy if already initiated.

Likely urinary source:

And patient is already on:

• Ceftriaxone
• Piperacillin tazobactam

These are likely effective empirical choices except if the patient has recent evidence of resistant organisms (e.g. SPICE group) for which a carbapenem is indicated.

Therapy not initiated or not effective:

Ceftriaxone is an appropriate recommendation if resistant organisms have not been identified in the past.

Likely Biliary or Colon source:

And patient already on:

• Piperacillin tazobactam
• Ceftriaxone

These are effective agents. Piperacillin tazobactam is often advocated because of excellent biliary levels and activity against some enterococci and anaerobes commonly found in GI infections. Ceftriaxone also achieves good biliary levels and is often given with metronidazole. If the patient is on ceftriaxone alone advise addition of metronidazole.

Therapy not initiated or not effective:

Piperacillin tazobactam is appropriate.

See Therapy Recommendations Cholecystitis-Cholangitis and Therapy Recommendations Diverticulitis

Personal protective equipment (PPE) is used for two reasons:

• To protect staff from blood or body fluid contamination
• To reduce the risk of cross infection through the reduction in contamination and transferring of microorganisms to other patients/residents, staff, visitors and the environment

Gloves

The hands of clinical staff are the most likely means of transmission of healthcare associated infection. Through hand washing and the appropriate use of gloves the risk of cross infection is minimized.

There are a number of materials used in the manufacture of gloves, including latex, nitrile and vinyl (PVC). The choice of material will depend on the type of task being performed, contact with chemicals and the risks associated with latex sensitization.

The use of vinyl gloves is not recommended for prolonged tasks that require manual dexterity or when contact with blood or body fluids is anticipated.

The purpose of wearing gloves is to either prevent the hands becoming contaminated with dirt or microorganisms, or to prevent the transfer of organisms already present on the skin or the hands. It is essential to ensure that hands are washed before putting on gloves and following the removal of gloves.

Selection of glove type

Most tasks require non-sterile gloves. These are made of latex or nitrile (for latex allergic users) and come in boxes with many gloves in each box in small, medium and large sizes.

Sterile gloves are worn to protect the patient during aseptic invasive procedures such as in the operating room. These gloves come in individually wrapped pairs in various numeric sizes.

Storage of disposable gloves

It is important to store latex and nitrile gloves separately at all times to avoid getting latex onto the nitrile gloves. This will include, and not be exclusive to, the clean utility room and within all clinical area where the gloves are available for use.

Gloves must be worn:

• When touching mucous membrane
• When changing a dressing, or having contact with non-intact skin
• When changing diapers or adult briefs
• When performing personal hygiene for clients
• When performing mouth care
• When indicated for Additional Precautions

Gloves should not be worn:

• When there is no risk of exposure/ splash/ contact with blood, body fluids and non-intact skin
• When assisting or feeding a patient
• For social touch
• When pushing a wheelchair
• When delivering meals, mail, clean linen
• For providing care to clients with intact skin, e.g. taking temperature

A further aspect of routine practices is the decision making process for patient placement. Options include single patient rooms, two patient rooms and multi-bedded rooms/bays.

Single room accommodation is always the preferred option. However, most facilities have limited resources in this area, and competing considerations when determining the appropriate placement of patients/residents.

Single patient rooms are always preferred when there is a concern about the transmission of an infectious agent. In situations that require prioritization of such accommodation, it is prudent to prioritize these rooms for patients/residents who pose a high cross infection risk to other patients/residents, particularly for those who are at increased risk of an adverse outcome from the acquisition of an infection.

Occasionally, due to the number of patients/residents who are colonized or infected with the same organism, cohorting the group of patients/residents in the same area may be an option (see ARO Room Placement).

The outbreaks of SARS in 2003 and recent swine flu pandemic have highlighted the need for vigilance and prompt implementation of infection prevention and control measures at the first point of encounter within a healthcare setting.

This UK Department of Health TV ad promoting good respiratory hygiene graphically highlighted the issue during the swine flu pandemic.

Catch it, Bin it, Kill it from Jim Hutchinson on Vimeo.

Respiratory hygiene/cough etiquette is targeted at patients/residents and accompanying family members and friends with undiagnosed transmissible respiratory infections, and applies to any person with signs of illness, including cough, congestion, rhinorrhea (runny nose) or increased production of respiratory secretions when entering a healthcare facility.

The elements of respiratory hygiene/cough etiquette include:

• Education of healthcare facility staff, patients/residents and visitors
• Posted signs, in languages appropriate to the population being served, with instructions to patients/residents and visitors
• Source control measures (e.g. covering the mouth and nose with a tissue when coughing and prompt disposal of used tissues, using surgical masks on the coughing person when tolerated and appropriate)
• Hand hygiene after contact with respiratory secretions
• Spatial separation, ideally more than 6 feet between persons with respiratory infection in common areas, when possible

It should be noted that although fever will be present in many respiratory infections, patients/residents who are very old or very young and patients/residents with pertussis and mild upper respiratory tract infections are often afebrile. Therefore, the absence of fever does not always exclude serious respiratory infections.

Patients/residents who have asthma, allergic rhinitis or chronic obstructive lung disease also may be coughing and sneezing. While these patients/residents often are not infectious, cough etiquette measures are prudent.

Healthcare personnel are advised to observe droplet precautions and hand hygiene when examining and caring for patients/residents with signs and symptoms of respiratory infection.

Healthcare personnel who have a respiratory infection are advised to avoid direct patient contact, especially with high risk patients/residents. If this is not possible, then a mask should be worn while providing patient care.

Modified from: Siegel, J.D., Rhinehart, E., Jackson, M. Chiarello, L. and the Healthcare Infection Control Practices Advisory Committee (2007) Guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings. June 2007