Healthcare-associated Pneumocystis jirovecii Pneumonia (PJP) Infection in HIV-negative Adults: a Multicenter Study.

BACKGROUND: Pneumocystis jirovecii pneumonia (PJP) is an opportunistic infection in immunocompromised patients. Clusters of PJP, especially among organ transplant recipients in clinic settings were described. Data regarding nosocomial PJP infection among inpatients are limited. OBJECTIVES: To assess the magnitude and characteristics of inpatient healthcare-associated PJP infection (HCA-PJP) in HIV-negative patients. METHODS: A retrospective chart review of hospitalized PJP patients was performed to identify HCA-PJP. The study was performed at six medical centers in Israel from 2006 to 2016. HCA-PJP was defined as cases of hospital-onset or those with documented contact with a PJP patient. We reviewed and cross-matched temporal and spatial co-locations of patients. Clinical laboratory characteristics and outcomes were compared. RESULTS: Seventy-six cases of PJP were identified. Median age was 63.7 years; 64% men; 44% hematological malignancies; 18% inflammatory diseases; and 61% steroid usage. Thirty-two patients (42%) were defined as HCA-PJP: 18/32 (23.6%) were hospitalized at onset and 14/32 (18.4%) had a previous encounter with a PJP patient. Time from onset of symptoms to diagnosis was shorter in HCA-PJP vs. community-PJP (3.25 vs. 11.23 days, P = 0.009). In multivariate analysis, dyspnea at presentation (odds ratio [OR] 16.79, 95% confidence interval [95%CI] 1.78-157.95) and a tendency toward higher rate of ventilator support (72% vs. 52%, P = 0.07, OR 5.18, 95%CI 0.7-30.3) were independently associated with HCA-PJP, implying abrupt disease progression in HCA-PJP. CONCLUSIONS: HCA-PJP was common. A high level of suspicion for PJP among selected patients with nosocomial respiratory infection is warranted. Isolation of PJP patients should be considered.

Is it financially beneficial for hospitals to prevent nosocomial infections?

BACKGROUND: Financial incentives represent a potential mechanism to encourage infection prevention by hospitals. In order to characterize the place of financial incentives, we investigated resource utilization and cost associated with hospital-acquired infections (HAI) and assessed the relative financial burden for hospital and insurer according to reimbursement policies. METHODS: We conducted a prospective matched case-control study over 18 months in a tertiary university medical center. Patients with central-line associated blood-stream infections (CLABSI), Clostridium difficile infection (CDI) or surgical site infections (SSI) were each matched to three control patients. Resource utilization, costs and reimbursement (per diem for CLABSI and CDI, diagnosis related group (DRG) reimbursement for SSI) were compared between patients and controls, from both the hospital and insurer perspective. RESULTS: HAIs were associated with increased resource consumption (more blood tests, imaging, antibiotic days, hospital days etc.). Direct costs were higher for cases vs. controls (CLABSI: $6400 vs. $2376 (p < 0.001), CDI: $1357 vs $733 (p = 0.047) and SSI: $6761 vs. $5860 (p < 0.001)). However as admissions were longer following CLABSI and CDI, costs per-day were non-significantly different (USD/day, cases vs. controls: CLABSI, 601 vs. 719, (p = 0.63); CDI, 101 vs. 93 (p = 0.5)). For CLABSI and CDI, reimbursement was per-diem and thus the financial burden ($14,608 and $5430 respectively) rested on the insurer, not the hospital. For SSI, as reimbursement was per procedure, costs rested primarily on the hospital rather than the insurer. CONCLUSION: Nosocomial infections are associated with both increased resource utilization and increased length of stay. Reimbursement strategy (per diem vs DRG) is the principal parameter affecting financial incentives to prevent hospital acquired infections and depends on the payer perspective. In the Israeli health care system, financial incentives are unlikely to represent a significant consideration in the prevention of CLABSI and CDI.

Successful Treatment of Antibiotic-resistant, Poly-microbial Bone Infection With Bacteriophages and Antibiotics Combination.

A patient with a trauma-related left tibial infection associated with extensively drug-resistant Acinetobacter baumannii and multidrug-resistant Klebsiella pneumoniae was treated with bacteriophages and antibiotics. There was rapid tissue healing and positive culture eradication. As a result, the patient's leg did not have to be amputated and he is undergoing rehabilitation.

Limited awareness of the effective timing of HIV post-exposure prophylaxis among people with high-risk exposure to HIV.

The effectiveness of post-exposure prophylaxis (PEP), a major strategy in the battle against HIV, depends on awareness of this modality and its proper timing among high-risk groups. While general awareness of PEP is improving, recently estimated to be 36-47% among men who have sex with men (MSM), PEP implementation remains disappointingly low and may be driven by limited awareness of effective PEP timing window. The level of detailed understanding of PEP timing and effectiveness among populations at risk has not been prospectively assessed to date. We prospectively evaluated, for the first time, actionable awareness regarding effective timing of PEP among a large cohort of individuals tested for HIV following unprotected sexual intercourse. Four hundred participants were assessed between December 2014 and February 2016. Overall awareness of the option of PEP was 60% and was significantly higher among male members of the LGBTQ community (75·5% as compared to 52·6% among heterosexual males) and those undergoing past HIV testing (67·1%). However, only 24% of individuals at risk were aware as to the proper timing of effective PEP treatment, thereby leading, in the majority of cases, to missing the window of opportunity for PEP treatment. This study highlights the lack of knowledge as to the specific requirements needed for effective PEP timing. Expanded advertising, better targeting of the heterosexual population, training of family physicians in the field of gender, sexuality, and LGBTQ medicine, may improve effective PEP availability, thereby reducing HIV transmission.

The prevalence and clinical significance of microcolonies when tested according to contemporary interpretive breakpoints for fluconazole against Candida species using E-test.

Changes in the interpretive-breakpoints for antifungals against various Candida species have raised the need to examine the significance of the phenomenon of the growth of microcolonies in agar diffusion inhibition zones, which has generally been considered negligible. The objective was to determine the incidence of cases in which microcolonies demonstrate fluconazole resistance according to current interpretive-breakpoints and whether their growth is associated with therapeutic failure. The fluconazole minimum inhibitory concentrations (MICs) of 100 blood culture isolates of Candida were performed by E-test on Roswell Park Memorial Institute (RPMI) agar and examined for the appearance of microcolonies. Fluconazole MICs of microcolonies were then determined over three generations. The significance of the phenomenon of microcolonies was determined according to clinical data retrieved from electronic files. Microcolonies were a common phenomenon among Candida isolates following incubation on RPMI agar, with a higher frequency among C. albicans isolates as compared to non-albicans Candida across generations (57-93% vs 31-93%, respectively) and a similar fluconazole susceptibility rate over three generations. The rate of microcolonies was similar in both patients with successful and unsuccessful outcome (41% vs 42%, respectively). Microcolonies are a common phenomenon. No increase in MIC was demonstrated throughout three generations of microcolony inoculation on RPMI, and no difference in clinical outcome was observed.

Early onset, non-rheumatic, group A streptococcal-associated myocarditis.

OBJECTIVES: Group A streptococcal (GAS) tonsillitis is reported as an uncommon cause of acute non-rheumatic fever (non-RF) myocarditis. The aim of this research was to study the occurrence, diagnosis, management and prognosis of this condition. METHODS: We conducted a retrospective computerised search through medical records of patients admitted to our tertiary medical center between 1998-2016 with the diagnosis of either acute rheumatic fever or non-RF streptococcal myocarditis based on criteria we developed and review the relevant literature from 1973-2016. RESULTS: We identified 283 cases diagnosed with acute myocarditis. Eight patients with non-RF GAS-myocarditis were identified, 7 of whom were men. Average age was 28.5 (22-35) years, and average latency period between onset of sore throat and chest pain 4.8 (3-10) days. Most patients presented with ST-segment elevations on the ECG and 2 underwent coronary catheterisation with presumed diagnosis of myocardial infarction. Three patients had heart failure, as documented by echocardiogram. All patients were treated with antibiotics and 6 patients received non-steroidal anti-inflammatory drugs (NSAIDs). All patients recovered with no evidence of heart failure a few months after the initial infection. One patient had a recurrent episode. CONCLUSIONS: Non-RF GAS myocarditis typically affects healthy young males and represents about 3% of all hospitalised patients with myocarditis. These patients may be mistakenly diagnosed with an acute rheumatic fever or myocardial infarction. The prognosis in generally good following treatment with antibiotics and possibly NSAIDs.

The Effect of Repeated Versus Initial Procalcitonin Measurements on Diagnosis of Infection in the Intensive Care Setting: A Prospective Observational Study.

Procalcitonin (PCT) measurement has been proposed to direct antibiotic use. We examined whether repeated PCT measurements (0, 6, and/or 12 hours) versus the initial measurement only (time 0) increased the sensitivity and specificity of PCT for diagnosing infection in intensive care unit patients. Infection was identified in 67/176 (38%) patients. The sensitivity of repeated versus the initial PCT measurement (with a cutoff value 0.5 ng/mL) was 52/67 (77%; 95% confidence interval [CI], 66%-87%) vs 46/67 (69%; 95% CI, 56%-79%; P = .04) and specificity 60/109 (55%; 95% CI, 45%-65%) vs 59/109 (54%; 95% CI, 44%-64%; P = 1.0). Repeat PCT evaluations over 12 hours did not provide a clinically significant improvement in diagnostic accuracy when compared to the initial single test.

Reduction in incidence of invasive fungal infection in patients receiving allogeneic stem cell transplantation using combined diagnostic-driven approach and itraconazole oral solution.

Invasive fungal infections are an important cause of morbidity and mortality after allogeneic haematopoietic stem cell transplantation. We evaluated, in our allogeneic stem cell transplant patients, the effect on the incidence of invasive fungal infection during neutropenia of a strategy combining a diagnostic-driven approach with chemoprophylaxis during higher risk periods of graft vs. host disease and prolonged neutropenia, using itraconazole oral solution with parenteral voriconazole bridging. One hundred and thirty patients admitted for allogeneic stem cell transplantation within two predefined 20 month periods were included in the study. Data for all patients were collected prospectively. Implementation of the protocol resulted in the administration of more prophylactic antifungals to more patients. Following implementation, there was a non-significant decrease in the overall number of invasive fungal infections (IFI) [11 of 65 patients (17.2%) vs. 4 of 65 patients (6.2%, P = 0.051)], as well as in the occurrence of invasive mould infections [8 of 65 patients (12.5%) vs. 2 of 65 patients (3.1%, P = 0.054)]. Survival rates at three and 6 months were not significantly affected. A combined diagnostic-driven approach and antifungal prophylaxis with oral itraconazole and an intravenous voriconazole bridging protocol, was associated with a reduced, albeit non-statistically significant, number of IFI in our medical centre.

Characterization of sil in invasive group A and G streptococci: antibodies against bacterial pheromone peptide SilCR result in severe infection.

Group G beta-hemolytic streptococcus (GGS) strains cause severe invasive infections, mostly in patients with comorbidities. GGS is known to possess virulence factors similar to those of its more virulent counterpart group A streptococcus (GAS). A streptococcal invasion locus, sil, was identified in GAS. sil encodes a competence-stimulating peptide named SilCR that activates bacterial quorum sensing and has the ability to attenuate virulence in GAS infections. We found that sil is present in most GGS strains (82%) but in only 25% of GAS strains, with a similar gene arrangement. GGS strains that contained sil expressed the SilCR peptide and secreted it into the growth medium. In a modified murine model of GGS soft tissue infection, GGS grown in the presence of SilCR caused a milder disease than GGS grown in the absence of SilCR. To further study the role of the peptide in bacterial virulence attenuation, we vaccinated mice with SilCR to produce specific anti-SilCR antibodies. Vaccinated mice developed a significantly more severe illness than nonvaccinated mice. Our results indicate that the sil locus is much more prevalent among the less virulent GGS strains than among GAS strains. GGS strains express and secrete SilCR, which has a role in attenuation of virulence in a murine model. We show that the SilCR peptide can protect mice from infection caused by GGS. Furthermore, vaccinated mice that produce specific anti-SilCR antibodies develop a significantly more severe infection. To our knowledge, this is a novel report demonstrating that specific antibodies against a bacterial component cause more severe infection by those bacteria.

Refractory Pseudomonas aeruginosa infections treated with phage PASA16: A compassionate use case series.

BACKGROUND: A growing number of compassionate phage therapy cases were reported in the last decade, with a limited number of clinical trials conducted and few unsuccessful clinical trials reported. There is only a little evidence on the role of phages in refractory infections. Our objective here was to present the largest compassionate-use single-organism/phage case series in 16 patients with non-resolving Pseudomonas aeruginosa infections. METHODS: We summarized clinical phage microbiology susceptibility data, administration protocol, clinical data, and outcomes of all cases treated with PASA16 phage. In all intravenous phage administrations, PASA16 phage was manufactured and provided pro bono by Adaptive Phage Therapeutics. PASA16 was administered intravenously, locally to infection site, or by topical use to 16 patients, with data available for 15 patients, mainly with osteoarticular and foreign-device-associated infections. FINDINGS: A few minor side effects were noted, including elevated liver function enzymes and a transient reduction in white blood cell count. Good clinical outcome was documented in 13 out of 15 patients (86.6%). Two clinical failures were reported. The minimum therapy duration was 8 days with a once- to twice-daily regimen. CONCLUSIONS: PASA16 with antibiotics was found to be relatively successful in patients for whom traditional treatment approaches have failed previously. Such pre-phase-1 cohorts can outline potential clinical protocols and facilitate the design of future trials. FUNDING: The study was funded in part by The Israeli Science Foundation IPMP (ISF_1349/20), Rosetrees Trust (A2232), United States-Israel Binational Science Foundation (2017123), and the Milgrom Family Support Program.

KPC-9, a novel carbapenemase from clinical specimens in Israel.

A bla(KPC-9) carbapenemase variant was discovered in isolates of Klebsiella pneumoniae and Escherichia coli from a single patient. It differed from bla(KPC-3) by one amino acid substitution (Val239Ala). The K. pneumoniae isolate was typed as ST258, as was the epidemic Israeli KPC-3 clone. bla(KPC-9) was found on a plasmid indistinguishable from pKpQIL that carries bla(KPC-3) in the epidemic clone. Compared to KPC-3, KPC-9 conferred less resistance to carbapenems and higher resistance to ceftazidime.

Comparison of two carbapenem-resistant Klebsiella pneumoniae clones: from a contained outbreak in a paediatric population and from a national epidemic.

OBJECTIVES: A refractory epidemic of carbapenem-resistant Klebsiella pneumoniae (CRKP) emerged in the adult population at our hospital in 2005, as in most Israeli hospitals. Contemporaneously, a different clone of CRKP caused an easily contained outbreak in a paediatric long-term care facility (LTCF) in Jerusalem. While previously identified host-related risk factors for colonization by these organisms undoubtedly contributed to these outbreaks, it is very likely that bacterial factors might be crucial in explaining the striking differences in transmissibility between the implicated strains. We therefore sought bacterial factors associated with these different epidemiological behaviours. METHODS: Seven CRKP isolated at our hospital and the LTCF during 2008-09 were examined by antimicrobial susceptibility testing and PFGE, and further analyses of these two clones was done using multilocus sequence typing and competition experiments. Plasmids were analysed by conjugation, restriction mapping, PCR and sequencing. RESULTS: Both clones were multidrug resistant and harboured identical plasmids carrying the bla(KPC-3) gene. The hyper-transmissible epidemic clone carried additional antibiotic resistance genes and hosted an additional plasmid. The clone from the LTCF did not demonstrate hyper-transmissible properties despite its presence in an institution of a type commonly plagued by the epidemic clone. Competition assays showed the more easily contained strain to be fitter. CONCLUSIONS: These findings suggest that neither the presence of the plasmid carrying the bla(KPC-3) gene nor relative survival fitness account for the hyper-transmissibility of the epidemic strain. The role of patient age in susceptibility to colonization by the epidemic strain should be investigated.

A carbapenem-resistant Klebsiella pneumoniae epidemic clone in Jerusalem: sequence type 512 carrying a plasmid encoding aac(6')-Ib.

OBJECTIVES: We characterized distinctive features of a hypertransmissible carbapenem-resistant Klebsiella pneumoniae (CRKP) clone that emerged at Hadassah Hospital, Ein-Kerem, Jerusalem, Israel, in 2006. METHODS: Eleven CRKP isolated at Hadassah Hospital during 2005-09 were examined by antimicrobial susceptibility testing, PFGE and multilocus sequence typing (MLST). Plasmids were analysed by conjugation, restriction mapping, PCR and sequencing. RESULTS: Divergence from the national epidemic sequence type (ST) ST258 to ST512 was observed early on. Carbapenem resistance was conferred by bla(KPC-3) carried on a plasmid apparently closely related to pKpQIL, also from Israel. This clone also carried a 15 kb plasmid, designated pAAC154, that carries a Tn1331 derivative containing the aac(6')-Ib gene. pAAC154 does not carry a bla(KPC) gene, but is similar to pS15, a plasmid from New York that carries bla(KPC-2). CONCLUSIONS: A single CRKP clone ST512 has spread efficiently in our region. In this clone, aac(6')-Ib, common in CRKP strains, is carried on a different plasmid from bla(KPC-3).

Translating a theory-based positive deviance approach into an applied tool: Mitigating barriers among health professionals (HPs) regarding infection prevention and control (IPC) guidelines.

BACKGROUND: Although a wide range of intervention programs and methods have been implemented to increase health professionals' (HPs) adherence with infection prevention and control (IPC) guidelines and decrease the incidence of healthcare associated infections (HAIs), a significant discrepancy remains between the guidelines and their implementation in practice. OBJECTIVES: This study proposes an applied tool based on the integrated theoretical framework of the positive deviance (PD) approach for developing more effective interventions to mitigate this discrepancy. METHODS: A qualitative study guided by the PD approach based on data from two sources: (1) in-depth archival analysis of systematic review articles, and (2) integration and synthesis of findings based on an extensive empirical study we conducted, involving 250 HPs (nurses, physicians, support staff and cleaning staff) from three governmental hospitals in Israel, over 35 months (January 2017 to November 2020). RESULTS: The barriers faced by HPs were classified into four main categories: (1) individual-motivational, (2) social-cultural, (3) organizational, and (4) work environment and resource-centered. For each barrier, we constructed a set of questions based on the PD approach. For each question, we adapted and applied methodological tools (e.g., in-depth interviews, focus groups, social network maps, video clips and simulations) to help solve the problem. CONCLUSION: Translating a theory-based approach into an applied tool that offers step-by-step actions can help researchers and practitioners adopt and implement the approach within intervention programs to mitigate barriers.

Association of Receiving a Fourth Dose of the BNT162b Vaccine With SARS-CoV-2 Infection Among Health Care Workers in Israel.

Importance: Despite the high 3-dose vaccination rate among health care workers (HCWs) in Israel, a high rate of SARS-CoV-2 breakthrough infections in this group was observed during the Omicron wave. As a result, the Israeli Ministry of Health decided to recommend a fourth vaccine dose to medical staff. Objective: To evaluate the benefit of a fourth BNT162b2 vaccine dose on the breakthrough infection rate among HCWs. Design, Setting, and Participants: This multicenter cohort study was performed in January 2022, the first month of the 4-dose vaccination campaign, during a surge of the Omicron variant wave. All health care workers at 11 general hospitals in Israel who had been vaccinated with 3 doses up to September 30, 2021, and had not contracted COVID-19 before the vaccination campaign were included. Exposures: Vaccination with a fourth dose of the BNT162b2 vaccine during January 2022. Main Outcomes and Measures: Breakthrough COVID-19 infections in 4-dose recipients vs 3-dose recipients measured by a polymerase chain reaction test result positive for SARS-CoV-2. Health care workers were tested based on symptoms or exposure. Results: A total of 29 611 Israeli HCWs (19 381 [65%] female; mean [SD] age, 44 [12] years) had received 3 vaccine doses between August and September 2021; of these, 5331 (18%) received the fourth dose in January 2022 and were not infected by the first week after vaccination. Overall breakthrough infection rates were 368 of 5331 (7%) in the 4-dose group and 4802 of 24280 (20%) in the 3-dose group (relative risk, 0.35; 95% CI, 0.32-0.39). Similar reductions were found in a matched analysis by the exact day of receiving the third vaccine (relative risk, 0.61; 95% CI, 0.54-0.71) and in a time-dependent Cox proportional hazards regression model (adjusted hazard ratio, 0.56; 95% CI, 0.50-0.63). In both groups, no severe disease or death occurred. Conclusions and Relevance: In this cohort study, the fourth BNT162b2 vaccine dose resulted in a reduced breakthrough infection rate among hospital staff. This reduction was lower than that observed after the third dose; nevertheless, considering the high infectivity of the Omicron variant, which led to critical medical staff shortages, a fourth vaccine dose should be considered to mitigate the infection rate among HCWs.

Macrolide resistance in Mycoplasma pneumoniae, Israel, 2010.

Macrolide resistance in Mycoplasma pneumoniae is often found in Asia but is rare elsewhere. We report the emergence of macrolide-resistant M. pneumoniae in Israel and the in vivo evolution of such resistance during the treatment of a 6-year-old boy with pneumonia.

An outbreak of achromobacter xylosoxidans associated with ultrasound gel used during transrectal ultrasound guided prostate biopsy.

PURPOSE: We describe an outbreak of Achromobacter xylosoxidans after transrectal ultrasound guided prostate biopsy at a urology unit at a tertiary care center as well as clinical and microbiological investigation, and intervention. MATERIALS AND METHODS: In September 2008, several days after undergoing transrectal ultrasound guided prostate biopsy, 4 patients were hospitalized with fever. We reviewed the procedure and infection control practices in the urology service. Environmental cultures were obtained from equipment and materials used for the procedure. Isolates were identified by routine laboratory procedures with molecular confirmation and characterized by pulsed field gel electrophoresis. RESULTS: A. xylosoxidans was isolated from the urine of 2 patients, of whom 1 also had a positive blood culture. Review of transrectal ultrasound guided prostate biopsy revealed that the lubricant gel used in the procedure, which the biopsy needle passes through, was held in a plastic container that was repeatedly refilled from a large bag. A. xylosoxidans was isolated from this container. Pulsed field gel electrophoresis showed that the isolates obtained from patients and the gel were identical. CONCLUSIONS: Contaminated lubricant gel was the cause of this outbreak. The practice of repeatedly refilling gel containers with nonsterile gel was replaced by the use of individual sterile gel sachets in each patient. No further cases occurred. During an invasive procedure involving a sterile body site, such as transrectal ultrasound guided prostate biopsy, using sterile gel is essential. Our experience emphasizes the crucial need to review all invasive procedures from an infection control perspective.

Improved ICU design reduces acquisition of antibiotic-resistant bacteria: a quasi-experimental observational study.

INTRODUCTION: The role of ICU design and particularly single-patient rooms in decreasing bacterial transmission between ICU patients has been debated. A recent change in our ICU allowed further investigation. METHODS: Pre-move ICU-A and pre-move ICU-B were open-plan units. In March 2007, ICU-A moved to single-patient rooms (post-move ICU-A). ICU-B remained unchanged (post-move ICU-B). The same physicians cover both ICUs. Cultures of specified resistant organisms in surveillance or clinical cultures from consecutive patients staying >48 hours were compared for the different ICUs and periods to assess the effect of ICU design on acquisition of resistant organisms. RESULTS: Data were collected for 62, 62, 44 and 39 patients from pre-move ICU-A, post-move ICU-A, pre-move ICU-B and post-move ICU-B, respectively. Fewer post-move ICU-A patients acquired resistant organisms (3/62, 5%) compared with post-move ICU-B patients (7/39, 18%; P = 0.043, P = 0.011 using survival analysis) or pre-move ICU-A patients (14/62, 23%; P = 0.004, P = 0.012 on survival analysis). Only the admission period was significant for acquisition of resistant organisms comparing pre-move ICU-A with post-move ICU-A (hazard ratio = 5.18, 95% confidence interval = 1.03 to 16.06; P = 0.025). More antibiotic-free days were recorded in post-move ICU-A (median = 3, interquartile range = 0 to 5) versus post-move ICU-B (median = 0, interquartile range = 0 to 4; P = 0.070) or pre-move ICU-A (median = 0, interquartile range = 0 to 4; P = 0.017). Adequate hand hygiene was observed on 140/242 (58%) occasions in post-move ICU-A versus 23/66 (35%) occasions in post-move ICU-B (P < 0.001). CONCLUSIONS: Improved ICU design, and particularly use of single-patient rooms, decreases acquisition of resistant bacteria and antibiotic use. This observation should be considered in future ICU design.

Severe influenza A (H1N1): the course of imaging findings.

BACKGROUND: An outbreak of respiratory illness caused by a novel swine-origin influenza virus (influenza A/H1N1 2009) that began in Mexico was declared a global pandemic by the World Health Organization in June 2009. The pandemic affected many countries, including Israel. OBJECTIVES: To compare the course of chest radiographic and computed tomography findings in patients who survived and those who died following admission to the intensive care unit (ICU) or intubation due to severe laboratory-confirmed swine-origin influenza A/H1N1 2009. METHODS: We retrospectively reviewed the patient records (267 radiographs, 8 CTs) of 22 patients (10 males, 12 females) aged 3.5-66 years (median 34) with confirmed influenza A/ H1N1 2009, admitted to the ICU and/or intubated in five major Israeli medical centers during the period July-November 2009. We recorded demographic, clinical, and imaging findings--including pattern of opacification, extent, laterality, distribution, zone of findings, and presence/absence of nodular opacities--at initial radiography and during the course of disease, and compared the findings of survivors and non-survivors. Statistical significance was calculated using the Wilcoxon (continuous variables) and Fisher exact tests. RESULTS: The most common findings on the initial chest radiography were airspace opacities, which were multifocal in 17 patients (77%) and bilateral in 16 (73%), and located in the lower or lower and middle lung zones in 19 patients (86%). Large airspace nodules with indistinct margins were seen in 8 patients (36%). Twelve patients survived, 10 died. Patients who died had multiple background illnesses and were significantly older than survivors (P = 0.006). Radiologic findings for the two groups were not significantly different. CONCLUSION: Airspace opacities, often with nodular appearance, were the most common findings among patients with severe influenza A/H1N1 2009. The course of radiologic findings was similar in patients with severe influenza A/ H1N1 2009 who survived and those who died.