How many people are estimated to have died due to HCAIs this question is required *?

Health Care–Associated Bloodstream Infections

•

General associations:

IV lines

Arterial lines

Central venous pressure (CVP) lines: Lead to catheter-associated bloodstream infection (CLABSI)

Phlebitis

Hyperalimentation

Lack of safe injection best practices

Fever possibly only presenting sign

Exit site of all vascular lines carefully evaluated for:

Erythema

Induration

Tenderness

Purulent drainage

Usual organisms for device-associated bacteremia:

S. aureus (including MRSA)

Staphylococcus epidermidis for long-term IV lines

Enterobacter spp.

Klebsiella spp.

Candida spp.

Pseudomonas aeruginosa may come from a water source or reflect cutaneous bacteria

Phlebitis in 1.3 million patients yearly

Approximately 10,000 annual deaths from IV sepsis

Prevention bundle to eliminate central line-associated bloodstream infections (CLABSIs):

Meticulous sterile technique during central catheter line insertion.

Emphasis should be placed on attention to detail, including handwashing, adherence to guidelines for catheter insertion and maintenance, appropriate use of antiseptic solutions such as chlorhexidine (CHG) to prepare the skin before central line insertion.

Modified catheter, for example, antiseptic-coated line, may reduce risk for endoluminal colonization and catheter-related sepsis in subclavian lines.

Decrease use of routine IVs and encourage PO intake.

Avoid using a femoral vein insertion site. Subclavian central line site is associated with lower infection rate than jugular.

Bundle to prevent CLABSIs includes hand hygiene, CHG skin prep for insertion of central lines, full barrier protection for insertion of central lines, daily assessment to remove unnecessary lines, insertion checklist.

Consider daily CHG baths in ICUs.

In the U.S., 50% decrease in CLABSI between 2014 and 2018.

Table E2 summarizes recommended strategies for prevention of catheter-related bloodstream infections (CR-BSI) in ICU patients.

Burden of Healthcare-Associated Infections in Developing Countries

HAIs are a serious problem in industrialized countries, with 1.7 million cases, and an estimated 100,000 deaths, per annum reported in the US alone [1]. However, with scant attention to infection control and poor quality of hospital care in most developing countries, HAIs are now recognized as a huge health burden in developing countries, too, responsible for both increased morbidity and mortality, and waste of precious resources. In addition, HAIs subvert patient expectations of quality medical care and increase negativity towards the formal health system in favor of other options, especially since the costs of HAIs are borne by the patients themselves in many developing countries. The World Health Organization (WHO) estimates that 1.4 million people suffer from HAIs worldwide. Furthermore, the risk of acquiring HAIs in developing countries is 2 to 20 times higher than in developed countries. Reducing the risk of HAIs faced by populations in developing countries is a major priority of the WHO [2].

The Burden of Health Care–Associated Infections

The Centers for Disease Control and Prevention (CDC) defines health care–associated infections as infections that patients acquire during the course of receiving health care treatment for other conditions.Nosocomial infection is a term that refers specifically to a health care–associated infection that develops in association with hospital care. The development of infection during the course of health care is not, however, limited to the acute care hospital setting. Thus,health care–associated infection is the preferred term in referring to the broader spectrum of infections that develop during the course of health care, wherever that care may be provided, including acute care hospitals, long-term care facilities, rehabilitation facilities, dialysis facilities, and even the patient’s home during the receipt of home care services.

The most extensive data regarding the incidence of and outcomes associated with health care–associated infections come from the acute care hospital setting.1 On the basis of a point prevalence study conducted in 183 U.S. hospitals in 2011, it was estimated that up to 1.4 million health care–associated infections occur in hospital patients each year, with approximately 75,000 associated deaths (Table 266-1). By 2015, there was about a 16% decrease, from 4 to 3.2%, in prevalence.2 Previous European studies have estimated that 4.1 million health care–associated infections occur in European acute care hospitals each year. Thus, approximately one of every 14 to 20 patients admitted to U.S. and European hospitals develops a health care–associated infection, making health care–associated infection one of the most common complications associated with the receipt of health care. Moreover, these data indicate that health care–associated infections are one of the top 10 causes of death in the United States. Whereas many of these health care–associated infection-associated deaths occur among patients who are already severely ill and who have a high likelihood of death due to their underlying disease, a substantial proportion of health care–associated infection-related deaths occur among persons who were otherwise expected to survive their hospitalization. In a single-center study, 31% of unexpected in-hospital deaths were determined to be possibly or probably related to a health care–associated infection. In addition to an increased risk of death, patients who develop health care–associated infections suffer a number of other adverse outcomes, including prolonged hospital stays, additional medical interventions and antibiotic treatment, discomfort, and loss of function and income. These statistics are particularly concerning when they are considered with the knowledge that many of these infections are preventable. In fact, a systematic review found that 55 to 70% of four of the most common types of health care–associated infections are preventable through the use of currently available, evidence-based preventive strategies (seeTable 266-1).

Safety, Quality and Public Reporting

Healthcare-associated infections are one of the most common preventable complications of hospitalized patients, and therefore are frequently used as indicators of the quality of patient care. Thus, the process and outcome data generated by infection control and other practitioners is relevant to patient safety and quality of care at the level of the institution, across institutions and extending to credentialing and governmental regulatory boards.31

As of 2014, 37 states (74%) in the USA had enacted legislation that requires healthcare facilities to publicly report HAIs through NHSN. Although there is a wide variation among US states on which outcome measures are reported, CLABSI, CAUTI, selected surgical site infections, hospital-onset MRSA bloodstream infections and CDI are most often reported. In 2013 the CDC Healthcare Infection Control Practices Advisory Committee (HICPAC) published consensus recommendations for public reporting10 which emphasize choosing consistent, standardized CDC definitions along with external validation of surveillance processes and HAI reporting, discouraging clinician veto and adjudication, ensuring feedback to healthcare providers and providing adequate infrastructure support.

Associated with the widespread adoption of quality improvement processes, a decrease in HAIs from an estimated 1.7 million HAI in 2002 to 721 800 HAI in 2011 has been observed.5

Prophylaxis of Health Care–Associated Infections

Despite ongoing prevention efforts over the last decade across the United States and globally, HAIs continue to result in morbidity, mortality, and increased costs. Twenty percent of HAIs are acquired in the critical care setting, and risk of HAI increases with length of critical care stay.61 The three most common critical care HAIs are catheter-associated urinary tract infection (CA-UTI), CLA-BSI, and ventilator-associated lower respiratory tract infections. Over the last decade, national device-associated HAI rates have declined somewhat, in particular because of implementation of bundled prevention strategies. The use of daily CHG bathing has been proved to be an effective method of both reducing the development of HAIs and preventing colonization of critical care patients with multidrug-resistant organisms (MDROs).62-65

In the largest published prospective study to date, daily bathing with 2% CHG–impregnated washcloths was implemented in a multicenter, cluster-randomized, nonblinded crossover trial.62 Primary outcomes included incidence rates of MDRO acquisition and rates of CLA-BSIs. Nine critical care settings or bone marrow transplant units were used. Patients were randomized to either daily bathing with CHG for 6 months or use of a nonantimicrobial bathing cloth, and in the second 6 months the daily bathing product was alternated. More than 7700 patients were enrolled, and a 23% reduction in MDRO acquisition rate was found. The MDRO acquisition rate was 5.1 cases per 1000 patient-days in the CHG bathing group, compared with 6.6 cases per 1000 patient-days in the standard bathing group; this was statistically significant. CHG-bathed patients had a CLA-BSI rate of 4.78 per 1000 patient-days, compared with 6.6 CLA-BSIs per 100 patient-days in the control group. This translated to a 28% lower rate of CLA-BSIs in those patients bathed with CHG, and this result was also statistically significant.

A 2012 meta-analysis to assess the efficacy of daily CHG bathing in reducing HAI occurrences in ICU patients concluded that there was benefit to the practice.63 One randomized and 11 nonrandomized trials were included in the analysis. CHG bathing led to a significant reduction in BSI rates and CLA-BSI rates, with a pooled odds ratio of 0.44. The authors noted that there was a wide variation across studies with respect to the type of product and concentration of CHG, along with differences in use of other infection-control practices, such as active surveillance cultures, nasal mupirocin use, and enhanced hand hygiene. Of note, adverse events were extraordinarily rare.

A more recent cluster-randomized crossover study of 9340 patients admitted to five ICUs in a tertiary medical center in the United States used a 10-week period of bathing with 2% CHG washcloths, a 2-week washout period, and then 10 weeks of bathing with nonbacterial washcloths.66 The primary outcome was a composite of CLA-BSI, CA-UTI, ventilator-associated pneumonia (VAP), andClostridioides difficile (formerlyClostridium difficile) rate. The study found no reduction in the primary outcome. However, of note, this study had low rates of HAIs and used a composite end point instead of looking at only CLA-BSI.

Healthcare-associated infections (HCAI) are a result of direct medical care; treatment in hospitals, care homes and the patient’s own residence; and contact with a healthcare setting. The implication of them include prolonged patient stay, reductions in bed availability and increased diagnostic testing and infection control procedures. Infections can be caused by indwelling medical devices, including ventilators, catheters, shunts and endoscopes; they can also occur following surgical procedures through contact with contaminated surfaces or air-borne fungal spores. The most common infections are ventilator-associated pneumonia, central-line-associated septicaemia, catheter-associated UTIs, C. difficile and surgical site wound infection. Several species of bacteria and fungi cause HCAI; the most widely publicised is the hospital ‘superbug’—MRSA, a common cause of bacteraemia and septicaemia. Antibiotic-resistant strains are difficult to defeat because of the lack of treatment options and because bacteria and fungi are known to colonise surgical and chronic wounds and grow as a biofilm. This chapter discusses biofilm-related HCAI and their detection, evidence of biofilm formation, host responses to microbial biofilms and preventative anti-biofilm strategies.

Healthcare-Associated Infections

Healthcare-associated infections (HAIs) are among the leading communicable and preventable causes of morbidity and mortality throughout the world. Nosocomial infections are those wherein a patient is exposed to and contracts disease while hospitalized or in another care facility. While great strides have been made in hospital sanitation, HAI still occurs in as many as 10 percent of admissions in developed countries. Recent CDC estimates place the number of nosocomial infections in the USA for 2002 at 1.7 million, a higher incidence than any notifiable disease. With a case mortality of nearly 6 percent, HAIs are also among the most deadly. Although progress has been made in HAI prevention, the organisms implicated are becoming resistant to conventional therapy.

MRSA is among the most virulent and treatment-resistant bacteria, now accounting for over 50 percent of wound infections in many hospitals. Rare reports of vancomycin-resistant Staphylococcus aureus (VRSA) cause alarm, proving that antibiotic resistance has transferred from other species. Treatment options for VRSA and vancomycin-resistant Enterococcus species are extremely limited, with major concern that these organisms could spread or become resistant to the few known effective therapies. The increasing number of immunodeficient patients has increased the importance of prevention of nosocomial infections (Box 4.7).

BOX 4.7

Prevention of Health Care Facility-Associated Infections: Key Elements of Standard Precautions

Commitment of facility management to infection monitoring and prevention

Continuous quality improvement on this topic

Sterile technique training and supervision

Surgical suite sterility procedures and monitoring

Hand hygiene as key to improvement throughout a facility

Gloves, gowns, masks

Safe injection practices and needle safety

Respiratory hygiene and cough etiquette

Environmental cleaning

Linens and waste disposal

Patient care equipment

Dialysis equipment and space

Catheter care sterility and regular change

Respirator/ventilator sterility and regular change

Central venous line sterile maintenance

Colonoscopy and other invasive device sterility

Reporting and follow-up

Where standards of infection control are deficient or lacking in both developed and developing countries, hospital patients and staff are vulnerable to serious infection. Of note, TB and hepatitis B exposure is common among health care workers, but preventable through airborne precautions and vaccination, respectively. In developing countries, deadly emerging viruses, such as avian influenza H5N1 and Ebola viruses, infect nursing, medical, and other staff as secondary cases.

A great obstacle in quantifying the impact of HAI is the lack of uniform and clear case definitions, as well as reliance, in most countries, on voluntary reporting by institutions. While many recommendations have been made, notably by the Society for Healthcare Epidemiology of America, no uniform regulations have been established to mandate reporting of HAIs. However, much work has been focused on prevention. Standard Precautions (formerly known as Universal Precautions) are a set of basic practices by which health care workers may reduce the spread of nosocomial infection among patients, visitors, and staff, as well as protect health workers from occupationally acquired disease. These include adequate hand-washing hygiene and use of protective barriers suited to specific risks. Expanded precautions and mandatory use of organism-specific clinical guidelines are necessary procedures in many health care institutions as protective measures.

The 2007 CDC and Healthcare Infection Control Practices Advisory Committee (HICPAC) guidelines provide recommendations applicable to all settings. In 2011 the CDC published evidence-based guidelines for minimum prevention expectations for safe ambulatory care settings. Organizational policy must be established for each institution by an integrated and authoritative department of infection control and epidemiology (CDC Guide to Infection Prevention, 2011).

In the USA, approximately one out of every 20 hospitalized patients will contract an HAI. Costs of HAI to US hospitals range from US$28.4 to US$45 billion (2007 dollars). With 20 percent of infections preventable, potential cost savings range from an estimated low of US$5.7 to US$6.8 billion annually; with 70 percent of infections preventable, cost savings range from US$25.0 to US$31.5 billion (CDC 2009 and Public Health Reports 2007).

As illustrated, the cost of nosocomial infections serves as a major consideration in planning health budgets. Reducing the risk of HAIs justifies substantial expenditure for hospital epidemiology and infection control activities. With the diagnosis-related group (DRG) payment system for hospital care (classified by diagnosis rather than by days of stay), the effective manager has a major incentive to minimize the risk of nosocomial infections to improve patient care. Infections can greatly prolong hospital stay, increasing serious complications, patient dissatisfaction, and health care costs.

The US Agency for Healthcare Research and Quality patient safety program initiated a program to reduce central line-associated bloodstream infections (CLABSIs) in newborns. CLABSIs are health care-associated infections of central vein or artery catheters, especially in premature low birth-weight babies. These catheters may be in place for long periods to provide fluids, nutrients, and medications, but they are readily subject to infections that seriously harm or kill infants or adults.

Neonatal intensive care units (NICUs) participating in this project included 100 NICUs in nine states caring for 8400 newborns. The project was to improve the safety of procedures of care of these infants with intravenous bloodstream infections, adopting safe practices and guidelines provided by the CDC. As a result, the program reduced in-hospital infections by 58 percent in less than a year and relied on the program’s prevention practice checklists and better communication to prevent an estimated 131 infections and up to 41 deaths and to avoid more than US$2 million in health care costs (AHQR, 2013).

Patient safety and prevention of infections are long-standing issues in health care, going back to Florence Nightingale at Scutari Hospital in the Crimea, Ignaz Semmelweiss in Vienna, and Joseph Lister in Glasgow in the nineteenth century (see Chapter 1), but they remain vital issues in health care management economics and epidemiology.

Adverse Outcomes Related to Health Care–Associated Infection

HAIs are a potentially highly modifiable contributor to a spectrum of adverse outcomes, across all gestational and postnatal ages, but especially in the most immature infants (Table 40.4). Studies from the NICHD NRN have demonstrated a striking increase in mortality in VLBW infants who experience late-onset infection (18% in infected infants vs 7% in uninfected infants), with even higher mortality rates for gram-negative or fungal sepsis (Stoll et al., 2002). Several studies have found the length of stay to increase because of sepsis: NICHD NRN data indicated that the mean length of stay increased from 60 to 79 days in VLBW infants, while the VON group found an increase in the length of stay of 4–7 days (Pessoa-Silva et al., 2001; Stoll et al., 2002; Payne et al., 2004). In the subset of infants with intestinal failure due to necrotizing enterocolitis, hospital length of stay and the duration of parenteral nutrition were greatly increased by the occurrence of infections (Cole et al., 2012). A study of VAP in pediatric intensive care units and NICU populations noted an increased duration of mechanical ventilation (by 3 days) (Foglia et al., 2007). There is also strong evidence that infections in VLBW infants are associated with an increased risk of adverse neurodevelopmental outcomes. One early study of more than 6000 ELBW infants found that infants who experienced infection had impaired head growth as well as a significantly increased risk of cerebral palsy, lower Bayley mental and psychomotor development indices, and visual deficits (Stoll et al., 2004a). A secondary analysis of the Trial of Indomethacin Prophylaxis in Preterms (944 ELBW infants) also confirmed that infection was an independent risk factor for neurodevelopmental impairment (Bassler et al., 2009). Most recently, an analysis by the NICHD NRN of trends from 2005 to 2012 noted a decrease in infections across all VLBW gestational ages in this time period, while also noting slight improvements in survival without major morbidity in infants born at 25–28 weeks' gestation; the authors suggest that at least some of this improvement may plausibly be related to the reduction in infection rates over the same period (Stoll et al., 2015).

Evidence regarding the adverse effects of excess antibiotic exposure continues to mount. Development of antibiotic resistance is a well-known concern, potentially facilitating the emergence and spread of resistant nosocomial pathogens within the NICU (Singh et al., 2002; Millar et al., 2008; Russell et al., 2012; Gibson et al., 2015). In addition, several recent investigations into the impact of gut microbial alterations in early life have suggested associations between early antibiotic exposure, gut microbial dysbiosis, and the occurrence of GI dysfunction, necrotizing enterocolitis, and sepsis, as well as long-term immune dysregulation and GI disorders (Cotten et al., 2009; Kuppala et al., 2011; Sherman et al., 2015; Vangay et al., 2015).

HAIs are also associated with significantly increased use of healthcare resources and healthcare costs (Tambyah et al., 2002; Payne et al., 2004; Kennedy et al., 2013; Zimlichman et al., 2013). One metaanalysis of the costs of HAIs in the United States estimated costs attributable to CLABSIs at $45,814 (95% CI $30,919–$65,245), to VAP at $40,144 (95% CI $36,286–$44,220), to surgical site infections at $20,785 (95% CI $18,902–$22,667), and to catheter-associated UTIs at $896 (95% CI $603–$1189) (Zimlichman et al., 2013). A retrospective study of HAIs in NICUs calculated an incremental cost of $16,800 attributable to bloodstream infections (Donovan et al., 2013), whereas another study in VLBW infants found a more modest cost increase but still amounting to thousands of dollars ($1280–$5875 per infection) (Payne et al., 2004). Attributable costs in a study of pediatric and neonatal VAP were estimated at $30,000 (Foglia et al., 2007).

Thus decreasing HAI rates in the NICU can reduce the risk of adverse events in infants during their hospital stay, thereby decreasing the incidence of short-term and long-term adverse outcomes, length of stay, and direct healthcare costs. HAIs have therefore become a very important focus of quality improvement efforts in NICUs across the United States and the world.

Introduction

Healthcare-acquired infections (HAIs) can put a significant physical and economic burden on hospitals and other healthcare institutions. A number of professional societies and organizations (CDC—Centers for Disease Control [1]; APIC—Association of Practitioners of Infection Control [2]; SHEA/IDSA—Society for Healthcare Epidemiology of America/Infectious Diseases Society of America [3]) have put forth recommendations toward the practice of preventing HAIs and/or monitoring HAIs within a particular setting or an institution. Additional efforts have also been put forth from the Centers for Medicare and Medicaid Services (CMS) to reduce preventable harm (which include HAIs) and improving patient safety. This CMS program essentially penalizes hospitals/healthcare institutions, in the form of reduced reimbursement, that rank low based on scoring criteria [4].

Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile are two well-known pathogens that have traditionally been identified as hospital-acquired infections [5–7]. However, it is now recognized that these pathogens are not exclusively nosocomial pathogens [7,8]. Risk factors that have been identified for MRSA include: (1) prior antibiotic usage, (2) current colonization with MRSA, (3) admission to the intensive care unit (ICU), (4) presence of skin and soft tissue infection, and (5) prior history of MRSA infection/colonization [3,9–11]. Healthcare-acquired (HA) and community-acquired (CA) MRSA strains can be differentiated by molecular typing and epidemiological factors [12]. Differences have also been observed for HA-MRSA and CA-MRSA strain prevalence and geography [13–15]. Risk factors for CA-MRSA overlap with risk factors for HA-MRSA, but CA-MRSA strains are specifically associated with societal activities that involve some level of skin contact/exposure (ie, sports and athletics, intravenous drug abusers) [16,17].

In 2006 and 2010, Jarvis et al. conducted an MRSA prevalence survey to estimate the burden and impact of MRSA to healthcare institutions in the United States. They observed that the US MRSA colonization prevalence rate was higher compared to the last time the survey was conducted in 2006, 66.4 per 1000 inpatients versus 46.3 per 1000 inpatients, respectively [18,19]. Interestingly, they observed a decrease in the MRSA infection rate from 35 per 1000 inpatients (2006) to 25.3 per 1000 inpatients (2010). The increased colonization rate and decreased infection rate may reflect the observation that a higher proportion of healthcare institutions (76% in 2010 vs 29% in 2006) had an active surveillance program in place for MRSA and an improved ability to identify those patients that are colonized with MRSA. With improved ability to detect MRSA colonization comes a more focused approach to controlling colonization and infection.

In Canada, it was shown that the rate of MRSA infections increased from 0.46 to 5.90 per 1000 admissions from 1995 to 2004 [20]. That same study showed that patients with MRSA required prolonged hospitalization, special control measures, and more expensive treatments, compared to methicillin-sensitive S. aureus (MSSA) infections. The total MRSA-associated financial burden to the Canadian healthcare system was estimated to be $82 million in 2004. Anderson et al. estimated that an MRSA surgical site infection (SSI) results in approximately $79,029 in hospital charges [21], compared to MSSA and uninfected controls where hospital charges were $55,667 and $38,735, respectively. Anderson and colleagues also showed a 5- to 6-day greater length of stay for MRSA SSIs versus MSSA SSIs [21]. Other studies show the significant economic and physical burden MRSA infections put on healthcare institutions [22–24].

Microbiology screening and testing have traditionally been performed using culture-based and other phenotypic methodologies. In general, clinical microbiology laboratories are now adopting molecular methods because results can be available to clinicians more rapidly versus what the traditional methods can offer. One of the bottlenecks in the time to result for the traditional microbiology testing is the incubation period required for culture growth. The shift to molecular testing has already happened in the clinical virology laboratories where it is now considered the new gold standard. This chapter will focus on MRSA and C. difficile as examples of HAIs and the molecular screening and diagnostic testing that are currently used in detecting these two pathogens.

Health Care–Associated Infections

Health care–associated infections represent the greatest public health impact of Acinetobacter, given the rapid spread of antibiotic-resistant strains and their continuing acquisition of additional resistance mechanisms. The application of molecular typing methods has revealed that a limited number of widespread clonal lineages of A. baumannii are responsible for hospital outbreaks worldwide.3 A. baumannii and the phenotypically indistinguishable A. nosocomialis and A. pittii cause the vast majority of health care–associated infections, but a review of clinical Acinetobacter isolates suggest A. lwoffii and A. ursingii may be emerging as possible pathogens.18 A. baumannii has increased in frequency as the cause of health care–associated pneumonia over the past 2 decades, to cause between 3% to 7% of cases.19,20 Among patients requiring mechanical ventilation for more than 5 days, Acinetobacter was the most frequent pathogen in one series, accounting for 26% of pneumonia cases.21 Acinetobacter also causes 1% to 2% of bloodstream infections associated with intravascular catheters, surgical site infections, and urinary tract infections.19 Less frequent health care–associated infections include meningitis after neurosurgery and wound infections in burn patients.22,23,24

Risk factors for A. baumannii colonization in the health care setting include residence in a nursing home, prolonged admission to an intensive care unit, and exposure to third-generation cephalosporins, fluoroquinolones, or carbapenems.25-30 The mortality associated with A. baumannii depends on infection type and underlying immunocompromise but is especially high in solid-organ transplant patients.31-34

The ability of Acinetobacter species to survive for weeks on surfaces within the hospital environment leads to prolonged outbreaks, and patient and staff movement between health care facilities results in regional spread.26,27,35-39 Essentially any moist or dry surface within a patient care area may become contaminated and serve as a reservoir for ongoing transmission, including sinks, faucets, humidifiers, hydrotherapy pools, curtains, pillows, bedrails, and equipment such as supply carts, infusion pumps, and equipment control touch pads.24,40-46 Patients with both recent and remote history of infection are able to contaminate their surrounding environment.46

Transmission of Acinetobacter within the health care setting occurs after lapses in proper hand hygiene and failure to disinfect mobile medical equipment and surfaces within patient care areas.47-49 Inadequate disinfection routines result in higher levels of environmental contamination and have been directly associated with patient colonization and subsequent Acinetobacter infection.50 Procedures that result in a spray of contaminated fluids, such as pulsatile lavage of wounds, may also lead to heavy environmental contamination.51 In addition to contaminated surfaces, airborne particles are believed to play a role in transmission of Acinetobacter, either by spread through open units with multiple beds or contamination of internal air filters of medical equipment.52-55 Air ionization has been proposed as a control method, which may either directly affect the bacteria or repel the dust containing Acinetobacter by changing the electrostatic characteristics of plastic items of medical equipment.56,57 An increase in health care–associated Acinetobacter infections during the warmer, more humid months has been reported, potentially owing to contamination of air handling systems.58,59

Timely investigation of outbreaks requires the combination of traditional epidemiologic surveillance with molecular techniques to help identify potential routes of transmission and implement control measures.60-62 Molecular genotyping may also reveal changes in the predominant strain of multidrug-resistant A. baumannii causing health care–associated outbreaks over time.63,64 Outbreak strains are typically more resistant to antibiotics and may be associated with specific clinical syndromes, highlighting the importance of molecular epidemiology.65-67