To determine the risk of Clostridium difficile transmission from index cases with C. difficile infection (CDI) to their household contacts and domestic pets.

A prospective study from April 2011 to June 2013.

Patients with CDI from Canadian tertiary care centers.

Patients with CDI, their household human contacts, and pets.

Epidemiologic information and stool or rectal swabs were collected from participants at enrollment and monthly for up to 4 months. Pulsed-field gel electrophoresis (PFGE) was performed on C. difficile isolates. Probable transmission was defined as the conversion of a C. difficile culture–negative contact to C. difficile culture–positive contact with a PFGE pattern indistinguishable or closely related to the index case. Possible transmission was defined as a contact with a positive C. difficile culture at baseline with a strain indistinguishable or closely related to the index case.

A total of 51 patients with CDI participated in this study; 67 human contacts and 15 pet contacts were included. Overall, 9 human contacts (13.4%) were C. difficile culture positive; 1 contact (1.5%) developed CDI; and 8 contacts were asymptomatic. Of 67 human contacts, probable transmission occurred in 1 human contact (1.5%) and possible transmission occurred in 5 human contacts (7.5%). Of 15 pet contacts, probable transmission occurred in 3 (20%) and possible transmission occurred in 1 (6.7%).

There was a high proportion of C. difficile culture positivity at 13.4% among human contacts and asymptomatic carriage of domestic pets reached 26.7%. These results suggest that household transmission of C. difficile may be a source of community-associated cases.

Infect Control Hosp Epidemiol 2016;1–7

Polymerase chain reaction (PCR) assays based on the detection of the toxin B gene are replacing enzyme-linked immunosorbent assay (ELISA)–based toxin production detection or cell cytotoxicity assay in most laboratories.

To determine the proportion of pediatric patients diagnosed withClostridium difficile infection by PCR who would have also been diagnosed by ELISA and to compare the clinical characteristics of PCR+/ELISA+ vs PCR+/ELISA− patients.

Using the microbiology laboratory information system, stool samples positive for C. difficile by PCR between October 2010 and July 2014 were identified. Using frozen stool specimens, an ELISA for toxin A and B was performed. A retrospective medical chart review was conducted to obtain demographic and clinical data. Duplicate samples were excluded.

A total of 136 PCR-positive samples underwent ELISA testing: 54 (40%) were positive for toxin A or B. The mean (SD) age of the entire cohort was 8.5 (6.2) years. There was no difference in age, gender, clinical manifestation, previous medical problems, and management between patients positive or negative by ELISA. However, patients positive by ELISA were more likely to have had a recent exposure to antibiotics (67.9% vs 50%; crude odds ratio, 2.1 [95% CI, 1.03–4.28]).

In our pediatric population, 60% of patients with C. difficile diagnosed by PCR had no toxin detectable by ELISA. ELISA-negative patients were less likely to have received an antibiotic recently compared with ELISA-positive patients. These results highlight the need to standardize laboratory criteria for the diagnosis of C. difficile infections in children.

Infect Control Hosp Epidemiol 2016;37:1087–1093

Staphylococcus aureus is a common cause of bacterial infections worldwide. It is most commonly carried in and transmitted from the anterior nares. Hosts are known to vary in their proclivity for S. aureus nasal carriage and may be divided into persistent carriers, intermittent carriers, and noncarriers, depending on duration of carriage. Mathematical models of S. aureus to predict outcomes of interventions have, however, typically assumed that all individuals are equally susceptible to colonization.

To characterize biases created by assuming a homogeneous host population in estimating efficacy of control interventions.

Mathematical model.

We developed a model of S. aureus carriage in the healthcare setting under the homogeneous assumption as well as a heterogeneous model to account for the 3 types of S. aureus carriers. In both models, we calculated the equilibrium carriage prevalence to predict the impact of control measures (reducing contact and decolonization).

The homogeneous model almost always underestimates S. aureus transmissibility and overestimates the impact of intervention strategies in lowering carriage prevalence compared to the heterogeneous model. This finding is generally consistent regardless of changes in model setting that vary the proportions of various carriers in the population and the duration of carriage for these carrier types.

Not accounting for host heterogeneity leads to systematic and substantial biases in predictions of the effects of intervention strategies. Further understanding of the clinical impacts of heterogeneity through modeling can help to target control measures and allocate resources more efficiently.

Infect. Control Hosp. Epidemiol. 2016;37(2):197–204

Antibiotic treatment for asymptomatic bacteriuria (ASB) is prevalent but often contrary to published guidelines.

To evaluate risk factors for treatment of ASB.

Retrospective observational study.

A tertiary academic hospital, county hospital, and community hospital.

Hospitalized adults with bacteriuria.

Patients without documented symptoms of urinary tract infection per Infectious Diseases Society of America (IDSA) criteria were classified as ASB. We examined ASB treatment risk factors as well as broad-spectrum antibiotic usage and quantified diagnostic concordance between IDSA and National Healthcare Safety Network criteria.

Among 300 patients with bacteriuria, ASB was present in 71% by IDSA criteria. By National Healthcare Safety Network criteria, 71% of patients had ASB; within-patient diagnostic concordance with IDSA was moderate (kappa, 0.52). After excluding those given antibiotics for nonurinary indications, antibiotics were given to 38% (62/164) with ASB. Factors significantly associated with ASB treatment were elevated urine white cell count (65 vs 24 white blood cells per high-powered field, P<.01), hospital identity (hospital C vs A, odds ratio, 0.34 [95% CI, 0.14–0.80], P =.01), presence of leukocyte esterase (5.48 [2.35–12.79], P<.01), presence of nitrites (2.45 [1.11–5.41], P=.03), and Escherichia coli on culture (2.4 [1.2–4.7], P=.01). Of patients treated for ASB, broad-spectrum antibiotics were used in 84%.

ASB treatment was prevalent across settings and contributed to broad-spectrum antibiotic use. Associating abnormal urinalysis results with the need for antibiotic treatment regardless of symptoms may drive unnecessary antibiotic use.

Infect. Control Hosp. Epidemiol. 2016;37(3):319–326

Compliance with hand hygiene in healthcare workers is fundamental to infection prevention yet remains a challenge to sustain. We examined fidelity reporting in interventions to improve hand hygiene compliance, and we assessed 5 measures of intervention fidelity: (1) adherence, (2) exposure or dose, (3) quality of intervention delivery, (4) participant responsiveness, and (5) program differentiation.

Systematic review

A librarian performed searches of the literature in PubMed, Cumulative Index to Nursing and Allied Health (CINAHL), Cochrane Library, and Web of Science of material published prior to June 19, 2015. The review protocol was registered in PROSPERO International Prospective Register of Systematic Reviews, and assessment of study quality was conducted for each study reviewed.

A total of 100 studies met the inclusion criteria. Only 8 of these 100 studies reported all 5 measures of intervention fidelity. In addition, 39 of 100 (39%) failed to include at least 3 fidelity measures; 20 of 100 (20%) failed to include 4 measures; 17 of 100 (17%) failed to include 2 measures, while 16 of 100 (16%) of the studies failed to include at least 1 measure of fidelity. Participant responsiveness and adherence to the intervention were the most frequently unreported fidelity measures, while quality of the delivery was the most frequently reported measure.

Almost all hand hygiene intervention studies failed to report at least 1 fidelity measurement. To facilitate replication and effective implementation, reporting fidelity should be standard practice when describing results of complex behavioral interventions such as hand hygiene.

Infect Control Hosp Epidemiol 2016;37:567–575

Nosocomial outbreaks caused by Salmonella are rare. We describe the investigation and control of a cluster of novel extended-spectrum β-lactamase (ESBL) Salmonella enterica serotype Isangi in a hospital in southeastern Michigan.

An epidemiologic investigation, including case-control study, assessment of infection control practices and environmental cultures, was performed to identify modes of transmission. Healthcare workers (HCWs) exposed to case patients were screened. Strain relatedness was determined using pulsed-field gel electrophoresis (PFGE); ESBL confirmation was conducted using real-time PCR. Control measures were implemented to prevent further transmission.

Between September 2 and October 22, 2015, 19 surgical patients, including 10 organ transplant recipients and 1 HCW, had positive S. Isangi cultures. Of these case patients and HCW, 13 had gastroenteritis, 2 had bacteremia, 1 had surgical-site infection, and 4 were asymptomatic. Pulsed-field gel electrophoresis (PFGE) showed 89.5% similarity among the isolates in these cases. Isolates with resistant-phenotypes possessed plasmid-mediated CTX-M15 ESBL. A total of 19 case patients were compared with 57 control participants. Case patients had significantly higher odds of exposure to an intraoperative transesophageal (TEE) probe (adjusted odds ratio 9.0; 95% confidence interval, 1.12–72.60; P=.02). Possible cross-transmission occurred in the HCW and 2 patients. Cultures of TEE probes and the environment were negative. The outbreak ended after removal of TEE probes, modification of reprocessing procedures, implementation of strict infection control practices, and enhanced environmental cleaning.

We report the first nosocomial ESBL S. Isangi outbreak in the United States. Multiple control measures were necessary to interrupt transmission of this gastrointestinal pathogen. Exposure to possibly contaminated TEE probes was associated with transmission. Periodic monitoring of reprocessing procedures of TEE probes may be required to ensure optimal disinfection.

Infect Control Hosp Epidemiol 2016;37:954–961

To determine the clinical diagnoses associated with the National Healthcare Safety Network (NHSN) pneumonia (PNEU) or lower respiratory infection (LRI) surveillance events

Retrospective chart review

A convenience sample of 8 acute-care hospitals in Pennsylvania

All patients hospitalized during 2011–2012

Medical records were reviewed from a random sample of patients reported to the NHSN to have PNEU or LRI, excluding adults with ventilator-associated PNEU. Documented clinical diagnoses corresponding temporally to the PNEU and LRI events were recorded.

We reviewed 250 (30%) of 838 eligible PNEU and LRI events reported to the NHSN; 29 reported events (12%) fulfilled neither PNEU nor LRI case criteria. Differences interpreting radiology reports accounted for most misclassifications. Of 81 PNEU events in adults not on mechanical ventilation, 84% had clinician-diagnosed pneumonia; of these, 25% were attributed to aspiration. Of 43 adult LRI, 88% were in mechanically ventilated patients and 35% had no corresponding clinical diagnosis (infectious or noninfectious) documented at the time of LRI. Of 36 pediatric PNEU events, 72% were ventilator associated, and 70% corresponded to a clinical pneumonia diagnosis. Of 61 pediatric LRI patients, 84% were mechanically ventilated and 21% had no corresponding clinical diagnosis documented.

In adults not on mechanical ventilation and in children, most NHSN-defined PNEU events corresponded with compatible clinical conditions documented in the medical record. In contrast, NHSN LRI events often did not. As a result, substantial modifications to the LRI definitions were implemented in 2015.

Infect Control Hosp Epidemiol 2016;37:818–824

To evaluate a central line care maintenance bundle to reduce central line–associated bloodstream infection (CLABSI) in non–intensive care unit settings.

Before-after trial with 12-month follow-up period.

A 1,250-bed teaching hospital.

Patients with central lines on 8 general medicine wards. Four wards received the intervention and 4 served as controls.

A multifaceted catheter care maintenance bundle consisting of educational programs for nurses, update of hospital policies, visual aids, a competency assessment, process monitoring, regular progress reports, and consolidation of supplies necessary for catheter maintenance.

Data were collected for 25,542 catheter-days including 43 CLABSI (rate, 1.68 per 1,000 catheter-days) and 4,012 catheter dressing observations. Following the intervention, a 2.5% monthly decrease in the CLABSI incidence density was observed on intervention floors but this was not statistically significant (95% CI, −5.3% to 0.4%). On control floors, there was a smaller but marginally significant decrease in CLABSI incidence during the study (change in monthly rate, −1.1%; 95% CI, −2.1% to −0.1%). Implementation of the bundle was associated with improvement in catheter dressing compliance on intervention wards (78.8% compliance before intervention vs 87.9% during intervention/follow-up; P<.001) but improvement was also observed on control wards (84.9% compliance before intervention vs 90.9% during intervention/follow-up; P=.001).

A multifaceted program to improve catheter care was associated with improvement in catheter dressing care but no change in CLABSI rates. Additional study is needed to determine strategies to prevent CLABSI in non–intensive care unit patients.

Infect Control Hosp Epidemiol 2016;37:692–698

Rates of multidrug-resistant gram-negative organisms are surpassing those of methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci in nursing homes (NHs).

To characterize the incidence and duration of carriage of ciprofloxacin-resistant Escherichia coli (CipREc) in NHs and identify those in the O25b-ST131 lineage.

We collected 227 CipREc isolates obtained by routine and regular surveillance of high-risk NH residents with indwelling devices. Repetitive element palindromic (REP)–polymerase chain reaction assay and multiplex polymerase chain reaction amplification for O25b-ST131 E. coli detection were performed using (GTG)5-primers and O25pabBspe and trpA2 primer pairs, respectively.

We found a high period prevalence of CipREc colonization (21.5%), high rates of recolonization with the same strain following clearing (0.46 recolonizations/ person/ year), and an acquisition incidence of 1.05 cases/1,000 person-days. Almost three-quarters of colonized residents carried strains in the O25b-ST131 E. coli lineage. Compared with isolates not in the lineage, O25b-ST131 isolates were carried significantly longer (10 vs 3 months). We identified 18 different REP-types; 2 occurred in 55% of the residents colonized with CipREc, and in more than 1 NH. Duration of CipREc carriage varied by REP-type and averaged 6 months.

CipREc occurred frequently in NH residents and is carried for long durations, and reacquisition following clearance is common

Trial registration. ClinicalTrials.gov identifier: NCT01062841.

Infect. Control Hosp. Epidemiol. 2016;37(4):440–447

To evaluate the expected and treatment outcomes of Thai infectious disease physicians (IDPs) regarding carbapenem-resistant Acinetobacter baumannii (CRAB) ventilator-associated pneumonia (VAP)

From June 1, 2014, to March 1, 2015, survey data regarding the expected and clinical success rates of CRAB VAP treatment were collected from all Thai IDPs. The expected success rate was defined as the expectation of clinical response after CRAB VAP treatment for the given case scenario. Clinical success rate was defined as the overall reported success rate of CRAB VAP treatment based on the clinical practice of each IDP. The expected and clinical success rates were divided into low (<60%), standard (60%–80%), and high (>80%) categories and were then compared with standard clinical response rates archived in the existing literature.

Of 183 total Thai IDPs, 111 (60%) were enrolled in this study. The median expected and clinical success rates were 68% and 58%, respectively. Using multivariate analysis, we determined that working in a hospital that implemented the standard intervention combined with an intensified infection control (IC) intervention for CRAB (adjusted odds ratio [aOR], 3.01; 95% confidence interval [CI], 1.17–7.73; P=.02) was associated with standard and high expected rates (>60%). Being a board-certified IDP (aOR, 5.76; 95% CI, 2.16–15.37; P<.01) and having higher number of ID consultation cases per month (aOR, 4.84; 95% CI, 1.98–11.80; P<.01) were associated with standard and high clinical success rates (>60%). We identified a significant correlation between expected and clinical success rates (r=0.58; P<.001).

Awareness of IC among IDPs can improve physicians’ expected and clinical success rates for CRAB VAP treatment, and treatment experience impacts overall treatment success.

Infect. Control Hosp. Epidemiol. 2015;37(1):61–69

To develop common indicators, relevant to both EU member states and the United States, that characterize and allow for meaningful comparison of antimicrobial stewardship programs among different countries and healthcare systems.

Modified Delphi process.

A multinational panel of 20 experts in antimicrobial stewardship.

Potential indicators were rated on the perceived feasibility to implement and measure each indicator and clinical importance for optimizing appropriate antimicrobial prescribing.

The outcome was a set of 33 indicators developed to characterize the infrastructure and activities of hospital antimicrobial stewardship programs. Among them 17 indicators were considered essential to characterize an antimicrobial stewardship program and therefore were included in a core set of indicators. The remaining 16 indicators were considered optional indicators and included in a supplemental set.

The integration of these indicators in public health surveillance and special studies will lead to a better understanding of best practices in antimicrobial stewardship. Additionally, future studies can explore the association of hospital antimicrobial stewardship programs to antimicrobial use and resistance.

Infect Control Hosp Epidemiol 2016:1–11

The goal of this long-term quasi-experimental retrospective study was to assess the impact of a 5-year serial infection control and antimicrobial stewardship intervention on surgical site infections (SSIs).

This study was conducted in a tertiary-care public teaching institution over a 5-year period from January 2010 to December 2014. All patients undergoing hepatobiliary surgery and liver, kidney, pancreas, and simultaneous pancreas–kidney transplantation were included. Outcomes were compared between a preintervention group (2010–2011) and a postintervention group (2012–2014).

A total of 1,424 procedures averaged an overall SSI rate of 11.2%. After implementation of the interventions, a decrease of 52.8% in SSI rates from 17.4% to 8.2% was observed (P<.001; odds ratio [OR], 2.1; 95% confidence interval [CI], 1.5–2.9). An overall significant decrease >50% (relative rate; P<.001) was observed in superficial incisional and organ-space infections between pre- and postintervention groups. In addition, a 54.9% decrease from 19.7% to 8.9% (P<.001; OR, 2.2; 95% CI, 1.4–3.5) and a 51.6% decrease from 15.5% to 7.5% (P=.001; OR, 2.2; 95% CI, 1.4–3.5) were observed for SSI rates in hepatobiliary surgery and solid organ transplantation, respectively. The antimicrobial stewardship intervention increased overall conformity to the internal surgical prophylaxis protocol by 15.2% (absolute rate) from 45.1% to 60.3% (P<.003; 95% CI, 5.4–24.9).

A long-term serial infection control and antimicrobial stewardship intervention decreased SSIs among patients undergoing hepatobiliary surgery and liver, kidney, pancreas, and simultaneous pancreas–kidney transplantation.

Infect Control Hosp Epidemiol 2016;1468–1474

Our objective was to estimate the per-infection and cumulative mortality and cost burden of multidrug-resistant (MDR) Acinetobacter healthcare-associated infections (HAIs) in the United States using data from published studies.

We identified studies that estimated the excess cost, length of stay (LOS), or mortality attributable to MDR Acinetobacter HAIs. We generated estimates of the cost per HAI using 3 methods: (1) overall cost estimates, (2) multiplying LOS estimates by a cost per inpatient-day ($4,350) from the payer perspective, and (3) multiplying LOS estimates by a cost per inpatient-day from the hospital ($2,030) perspective. We deflated our estimates for time-dependent bias using an adjustment factor derived from studies that estimated attributable LOS using both time-fixed methods and either multistate models (70.4% decrease) or matching patients with and without HAIs using the timing of infection (47.4% decrease). Finally, we used the incidence rate of MDR Acinetobacter HAIs to generate cumulative incidence, cost, and mortality associated with these infections.

Our estimates of the cost per infection were $129,917 (method 1), $72,025 (method 2), and $33,510 (method 3). The pooled relative risk of mortality was 4.51 (95% CI, 1.10–32.65), which yielded a mortality rate of 10.6% (95% CI, 2.5%–29.4%). With an incidence rate of 0.141 (95% CI, 0.136–0.161) per 1,000 patient-days at risk, we estimated an annual cumulative incidence of 12,524 (95% CI, 11,509–13,625) in the United States.

The estimates presented here are relevant to understanding the expenditures and lives that could be saved by preventing MDR Acinetobacter HAIs.

Infect Control Hosp Epidemiol 2016;1–7

To design better antimicrobial stewardship programs, detailed data on the primary drivers and patterns of antibiotic use are needed.

To characterize the indications for antibiotic therapy, agents used, duration, combinations, and microbiological justification in 6 acute-care US facilities with varied location, size, and type of antimicrobial stewardship programs.

Retrospective medical chart review was performed on a random cross-sectional sample of 1,200 adult inpatients, hospitalized (>24 hrs) in 6 hospitals, and receiving at least 1 antibiotic dose on 4 index dates chosen at equal intervals through a 1-year study period (October 1, 2009–September 30, 2010).

Infectious disease specialists recorded patient demographic characteristics, comorbidities, microbiological and radiological testing, and agents used, dose, duration, and indication for antibiotic prescriptions.

On the index dates 4,119 (60.5%) of 6,812 inpatients were receiving antibiotics. The random sample of 1,200 case patients was receiving 2,527 antibiotics (average: 2.1 per patient); 540 (21.4%) were prophylactic and 1,987 (78.6%) were therapeutic, of which 372 (18.7%) were pathogen-directed at start. Of the 1,615 empirical starts, 382 (23.7%) were subsequently pathogen-directed and 1,231 (76.2%) remained empirical. Use was primarily for respiratory (27.6% of prescriptions) followed by gastrointestinal (13.1%) infections. Fluoroquinolones, vancomycin, and antipseudomonal penicillins together accounted for 47.1% of therapy-days.

Use of broad-spectrum empirical therapy was prevalent in 6 US acute care facilities and in most instances was not subsequently pathogen directed. Fluoroquinolones, vancomycin, and antipseudomonal penicillins were the most frequently used antibiotics, particularly for respiratory indications.

Infect. Control Hosp. Epidemiol. 2015;37(1):70–79

To identify themes associated with patient perceptions of antibiotic use and the role of patients in inpatient antimicrobial stewardship.

We conducted semi-structured interviews with 30 hospitalized patients using the Health Belief Model as the framework for questions and analysis.

An academic tertiary care hospital in Madison, Wisconsin.

A total of 30 general medicine inpatients receiving at least 1 anti-infective medication were interviewed.

Participants recognized antibiotic resistance as a serious public health threat but expressed low perceived susceptibility to being personally affected by antibiotic resistance. Views of susceptibility were influenced by a high degree of trust in physicians and misperceptions regarding the mechanisms underlying resistance. Participants expressed high self-efficacy and a desire to be involved in their health care. Perceived roles for patients in preventing the inappropriate use of antibiotics ranged from asking questions and speaking up about concerns to active involvement in decision making regarding antibiotic treatments. Few participants reported being offered the opportunity to engage in such shared decision making while hospitalized.

Our findings suggest an important role for patients in improving antibiotic use in hospitals. However, patient engagement has not been recognized as a critical component of antimicrobial stewardship programs. Our study suggests that the likelihood of patient engagement in stewardship practices is currently limited by low perceived susceptibility and lack of cues to act. Further investigation into how patients may be engaged as good stewards of antibiotics may reveal new ways to improve antibiotic prescribing practices in the inpatient setting.

Infect Control Hosp Epidemiol 2016;37:576–582

Hospital-acquired infection (HAI) data are reported to the public on the Centers for Medicare and Medicaid Services (CMS) Hospital Compare website. We previously found that public understanding of these data is poor. Our objective was to develop an improved method for presenting HAI data that could be used on the CMS website.

Randomized controlled trial comparing understanding of data presented using the current CMS presentation strategy versus a new strategy.

A 760-bed tertiary referral hospital.

A total of 61 patients were randomly selected within 24 hours of admission.

Participants were shown HAI data as presented on the CMS Hospital Compare website (control arm) or data formatted using a new method (experimental arm).

No statistically significant demographic differences were identified between study arms. Although 47% percent of participants said a website for comparing hospitals would have been helpful, only 10% had ever used such a website. Participants viewing data using the new presentation strategy compared hospitals correctly 56% of the time, compared with 32% in the control arm (P=.0002).

Understanding of HAI data increased significantly with the new data presentation method compared to the method currently used on the CMS Hospital Compare website. Many participants expressed interest in a website for comparing hospitals. Improved methods for presenting CMS HAI data, such as the one assessed here, should be adopted to increase public understanding.

Infect Control Hosp Epidemiol 2016;1–6

To determine the source of a Legionella pneumophila serogroup 5 nosocomial outbreak and the role of the heat exchanger installed on the hot water system within the previous year.

A 400-bed tertiary care university hospital in Sherbrooke, Canada.

Hot water samples were collected and cultured for L. pneumophila from 25 taps (baths and sinks) within wing A and 9 taps in wing B. Biofilm (5) and 2 L water samples (3) were collected within the heat exchangers for L. pneumophila culture and detection of protists. Sequence-based typing was performed on strain DNA extracts and pulsed-field gel electrophoresis patterns were analyzed.

Following 2 cases of hospital-acquired legionellosis, the hot water system investigation revealed a large proportion of L. pneumophila serogroup 5 positive taps (22/25 in wing A and 5/9 in wing B). High positivity was also detected in the heat exchanger of wing A in water samples (3/3) and swabs from the heat exchanger (4/5). The outbreak genotyping investigation identified the hot water system as the source of infections. Genotyping results revealed that all isolated environmental strains harbored the same related pulsed-field gel electrophoresis pattern and sequence-based type.

Two cases of hospital-acquired legionellosis occurred in the year following the installation of a heat exchanger to preheat hospital hot water. No cases were reported previously, although the same L. pneumophila strain was isolated from the hot water system in 1995. The heat exchanger promoted L. pneumophila growth and may have contributed to confirmed clinical cases.

Infect. Control Hosp. Epidemiol. 2016;1475–1480