Case Study 6: Outbreak in a Neonatal Intensive Care Unit Session Overview | Homework Solution

Case Study 6: Outbreak in a Neonatal Intensive Care Unit Session Overview

Instructions

For the purposes of this exercise, you will be asked to work in groups to participate in a healthcare associated infection investigation. Information regarding the scenario will be provided to you in parts, each of which will be followed by related discussion questions. Choose one group member to read each segment of information aloud to the rest of the group. After receiving the information, work as a team to formulate answers to each discussion question.

Intended Audience

All public health, medical, veterinary, pharmacy, emergency management, Outbreak in a Neonatal Intensive Care hospital and other professionals interested in public health preparedness and field epidemiology.

Time Required (estimated)

90 minutes

Learning Objectives

• Describe infection control practices in a healthcare setting
• Calculate disease prevalence, case-fatality rate, and odds ratio
• Create a histogram of cases over time
• Choose an appropriate epidemiological study design, given information about an outbreak
• Interpret epidemiologic study results

Case Study 6: Outbreak in a Neonatal Intensive Care Unit Pre-Test

1. Which of the following describe contact precautions to prevent the spread of infection in a hospital setting?
   1. Limiting patient movement Outbreak in a Neonatal Intensive Care
   2. Providing gown and gloves for patient
   3. Using dedicated equipment
   4. Cleaning and disinfecting patient room daily
   5. All of the above are contact precautions
   6. A, B, and D only

3. Prevalence is:
   1. number of deaths in infected persons total number of infected persons
   2. number or cases (new and existing) population at risk of infection
   3. number or cases (new and existing) total number of infected persons
   4. none of the above
4. True or False: In a case control-study, the controls should represent the population that gave rise to the case

Case Study 6: Outbreak in a Neonatal Intensive Care Unit Student Guide

1. What pertinent information would be helpful for you and the physician to know regarding this patient?
2. What infectious agents would be of greatest concern to the physician? Outbreak in a Neonatal Intensive Care
3. Could the mother be the source of infection, why or why not?
4. What might be other sources of infection in this patient?
5. Would you consider this a hospital acquired infection? Discuss what factors would lead you to determine if an infection is hospital.

Update 4: Day 2

You receive a call from the ICP, and the results of the laboratory diagnostic tests came back positive for Pseudomonas aeruginosa (su-doe-mo-nas air-rudge-i-nosa). You and the ICP are immediately concerned about the potential spread throughout the NICU and the rest of the hospital. Below is what you know about this pathogen:

1. aeruginosa is one of the most common hospital acquired pathogens and can cause severe infections in hospitalized patients. It occurs naturally in the environment, and can be found in soil, water, plants and animals. P. aeruginosa is an opportunistic pathogen, meaning that it predominately infects persons with compromised immune systems. Infection with the bacteria can be localized or systemic if it enters the bloodstream. Outbreak in a Neonatal Intensive Care A 2011 study in the New England Journal of Medicine showed that P. aeruginosa caused 7% of all healthcare-associated infections, including 13% of healthcare associated pneumonia cases. Notably, there are now multidrug resistant strains of P. aeruginosa that cause approximately 400 deaths per year in the U.S. Within the healthcare setting, outbreaks of P. aeruginosa have been linked to contaminated respiratory, endoscopic, urodynamic and pressure monitoring equipment, contaminated sinks, products (e.g., eye drops), tap and bottled water, and even healthcare workers. P. aeruginosa infection is treatable, although acute infections in immunocompromised patients have resulted in a 30% – 60% mortality rate.
2. What steps should the infection control practitioner take to ensure the infection does not spread to other patients?
3. Considering the information given, does it warrant a full investigation into the source of the infection?
4. Aside from an outbreak of disease, what might be other explanations of a rise in reportable diseases? Are these explanations likely for the observed causes of aeruginosa? Outbreak in a Neonatal Intensive Care
5. What is the prevalence of aeruginosa infections in patients who visited the NICU more than 2 days? Prevalence is a proportion that measures disease in a given population that is considered to be at risk. Prevalence is found by dividing the number of infected persons by the total number of people in the population at risk:

Prevalence = number or cases (new and existing)

population at risk of infection

10. Calculate the case-fatality rate of infected patients from the NICU since January of the previous year. Case-fatality rate is the proportion of deaths in infected persons among the total number of infected persons (Note: Despite its name, a case fatality rate is not a true rate, but simply a proportion).

Case-fatality rate = number of deaths in infected persons

total number of infected persons

Table 1. Cases of P. aeruginosa, January 2014-March 2015

11. Construct a histogram plotting the number of cases, by type of infection, for each month of diagnosis beginning with January 2014 and ending in March 2015. (Hint: Plot Blood and ETT on the same graph, differentiated by shading). Outbreak in a Neonatal Intensive Care
12. Look at the histogram you created. Is this histogram an epidemic curve? Why or why not?
13. What are the next steps in determining the source of the outbreak?
14. Considering that all cases are on mechanical ventilators and a large number of patients had bacterial colonization on endotracheal tubes, what control measures, if any do you implement?

Update 8

Based on the findings of your research of recent infections in the NICU, you are interested in the possible link between endotracheal tubes and the P. aeruginosa infections, but do not want to narrow your focus before obtaining more evidence to confirm your suspicions. You begin by requesting environmental samples from surfaces in the NICU: ventilator equipment, faucets, sink drains, hand lotion, and cleaning agents.

Worried about infections spread via healthcare workers, you obtain cultures from ear canals and hands of any healthcare worker working in the NICU, as ear canals and hands are common colonization sites. You also questioned the workers about recent history of skin or ear infections, and workers’ fingernail length was assessed by the ICP and recorded Outbreak in a Neonatal Intensive Care.

The results of the environmental assessment reveal that P. aeruginosa was isolated from 2 sink drains—no other samples tested positive. From the healthcare worker specimen collection, you find that 2 NICU nurses had P. aeruginosa isolated from their hands, but not from their ear canals. You also note that on inspection of their hands, one nurse had long natural fingernails (nurse A) and the second nurse had short natural fingernails (nurse B).

You decide to conduct an epidemiologic investigation to look at factors that might have contributed to P. aeruginosa infection.

15. Given this information what type of epidemiologic study design would you use?
16. You decide to conduct a case-control Discuss what criteria should be used to classify cases and controls.
17. The odds ratio for contact with an infected nurse was 1.21, with a 95% confidence interval of 0.35 – 4.65. Do these results imply that contact with an infected nurse was a risk factor for developing aeruginosa infection? Why or why not?

Table 2. Number of Cases and Controls in Contact with an Infected Nurse

18. From table 2 above, calculate the odds of acquiring infection if you had contact with the infected, long-nailed nurse within this study. Outbreak in a Neonatal Intensive Care The odds of acquiring infection from an infected nurse is found by dividing the number of cases who had contact with the nurse by the number of controls having contact with the
19. Using the same table, calculate the odds of acquiring infection if you did not have contact with the long-nailed infected nurse. The odds of being a case if you did not have contact with the long-nailed infected nurse is found by dividing the number of cases who did not have contact with the nurse by the number of controls who did not have contact with the Outbreak in a Neonatal Intensive Care
20. Calculate the disease odds ratio using the data provided. A disease odds ratio is found by obtaining the ratio of the probability of being a case among the exposed and the probability of being a case among the non-exposed. These two probabilities have been found in questions 18 and 19, and were 0.54 and 083.

Disease odds ratio = Outbreak in a Neonatal Intensive Care odds of infection & having contact with long-nailed infected nurses odds of infection & not having contact w/ long-nailed infected nurse.

References

Anderson-Berry AL, Bellig LL, Ohning BL. Neonatal sepsis. eMedicine. 2014. Available at: http://www.emedicine.com/PED/topic2630.htm. Accessed April 6, 2016.

Aschengrau A, Seage GR. Essentials of Epidemiology in Public Health. Sudbury: Jones and Bartlett Publishers, Inc; 2003. Outbreak in a Neonatal Intensive Care

Bodey GP, Bolivar R, Fainstein V, Jadeja L. Infections caused by Pseudomonas aeruginosa. Rev Infect Dis 1983; 5: 279-313.

Centers for Disease Control and Prevention. Healthcare-associated infections (HAIs). 2015. Available at http://www.cdc.gov/HAI/surveillance/index.html. April 6, 2016.

Centers for Disease Control and Prevention. Pseudomonas aeruginosa in healthcare settings. 2014. Available at http://www.cdc.gov/HAI/organisms/Pseudomonas.html. April 6, 2016.

Magill SS, Edwards JR, Bamberg W, Beldavs ZG, Dumyati G, Kainer MA, et al. Multistate point-prevalence survey of health care-associated infections. Outbreak in a Neonatal Intensive Care N Engl J Med 2014; 370:1198-1208.

Moolenaar RL, Crutcher JM, San Joaquin VH, et al. A prolonged outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit: did staff fingernails play a role in disease transmission? Infect Control Hosp Epidemiol 2000; 21:80-85. Get Exporting from Canada Homework Help!! Outbreak in a Neonatal Intensive Care

Naze F, Jouen E, Randriamahazo RT, Simac C, Laurent P, Bleriot A, et al. Pseudomonas aeruginosa outbreak linked to mineral water bottles in a neonatal intensive care unit: fast typing by use of high-resolution melting analysis of a variable-number tandem- repeat locus. J Clin Microbiology 2010;48(9):3146-3152.

Occupational Safety and Health Standards (OSHA). 1910.1030. Outbreak in a Neonatal Intensive Care Bloodborne pathogens: Toxic and Hazardous Substances. Occupational Safety and Health Administrator. US Department of Labor.