Last data update: Nov 04, 2024. (Total: 48056 publications since 2009)
Records 1-7 (of 7 Records) |
Query Trace: Kozak NA[original query] |
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Legionnaires' disease case-finding algorithm, attack rates, and risk factors during a residential outbreak among older adults: an environmental and cohort study
Silk BJ , Foltz JL , Ngamsnga K , Brown E , Munoz MG , Hampton L , Jacobs-Slifka K , Kozak NA , Underwood JM , Krick J , Travis T , Farrow O , Fields BS , Blythe D , Hicks LA . BMC Infect Dis 2013 13 (1) 291 BACKGROUND: During a Legionnaires' disease (LD) outbreak, combined epidemiological and environmental investigations were conducted to identify prevention recommendations for facilities where elderly residents live independently but have an increased risk of legionellosis. METHODS: Survey responses (n = 143) were used to calculate attack rates and describe transmission routes by estimating relative risk (RR) and 95% confidence intervals (95% CI). Potable water collected from five apartments of LD patients and three randomly-selected apartments of residents without LD (n = 103 samples) was cultured for Legionella. RESULTS: Eight confirmed LD cases occurred among 171 residents (attack rate = 4.7%); two visitors also developed LD. One case was fatal. The average age of patients was 70 years (range: 62--77). LD risk was lower among residents who reported tub bathing instead of showering (RR = 0.13, 95% CI: 0.02--1.09, P = 0.03). Two respiratory cultures were characterized as L. pneumophila serogroup 1, monoclonal antibody type Knoxville (1,2,3), sequence type 222. An indistinguishable strain was detected in 31 (74%) of 42 potable water samples. CONCLUSIONS: Managers of elderly-housing facilities and local public health officials should consider developing a Legionella prevention plan. When Legionella colonization of potable water is detected in these facilities, remediation is indicated to protect residents at higher risk. If LD occurs among residents, exposure reduction, heightened awareness, and clinical surveillance activities should be coordinated among stakeholders. For prompt diagnosis and effective treatment, clinicians should recognize the increased risk and atypical presentation of LD in older adults. |
Identification of Legionella in the environment
Kozak NA , Lucas CE , Winchell JM . Methods Mol Biol 2013 954 3-25 Legionella is ubiquitous in freshwater systems worldwide and can also be found in soil. Legionellosis may be caused by inhalation of aerosolized water or soil particles containing Legionella. Isolation of Legionella from the environment is an essential step in outbreak investigation and may also be performed within the context of a hazard analysis and control risk management plan. Culture remains the gold standard for detection of Legionella in environmental samples. Specific properties of environmental sites that could be a source of Legionella contamination, collection of samples from such sites, and procedures for culture of these samples for Legionella are described in this chapter. |
Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water
Yoder JS , Straif-Bourgeois S , Roy SL , Moore TA , Visvesvara GS , Ratard RC , Hill VR , Wilson JD , Linscott AJ , Crager R , Kozak NA , Sriram R , Narayanan J , Mull B , Kahler AM , Schneeberger C , da Silva AJ , Poudel M , Baumgarten KL , Xiao L , Beach MJ . Clin Infect Dis 2012 55 (9) e79-85 BACKGROUND: Naegleria fowleri is a climate-sensitive, thermophilic ameba found in the environment, including warm, freshwater lakes and rivers. Primary amebic meningoencephalitis (PAM), which is almost universally fatal, occurs when N. fowleri-containing water enters the nose, typically during swimming, and N. fowleri migrates to the brain via the olfactory nerve. In 2011, 2 adults died in Louisiana hospitals of infectious meningoencephalitis after brief illnesses. METHODS: Clinical and environmental testing and case investigations were initiated to determine the cause of death and to identify the exposures. RESULTS: Both patients had diagnoses of PAM. Their only reported water exposures were tap water used for household activities, including regular sinus irrigation with neti pots. Water samples, tap swab samples, and neti pots were collected from both households and tested; N. fowleri were identified in water samples from both homes. CONCLUSIONS: These are the first reported PAM cases in the United States associated with the presence of N. fowleri in household plumbing served by treated municipal water supplies and the first reports of PAM potentially associated with the use of a nasal irrigation device. These cases occurred in the context of an expanding geographic range for PAM beyond southern tier states with recent case reports from Minnesota, Kansas, and Virginia. These infections introduce an additional consideration for physicians recommending nasal irrigation and demonstrate the importance of using appropriate water (distilled, boiled, filtered) for nasal irrigation. Furthermore, the changing epidemiology of PAM highlights the importance of raising awareness about this disease among physicians treating persons showing meningitislike symptoms. |
Survey of Legionella species found in Thai soil
Travis TC , Brown EW , Peruski LF , Siludjai D , Jorakate P , Salika P , Yang G , Kozak NA , Kodani M , Warner AK , Lucas CE , Thurman KA , Winchell JM , Thamthitiwat S , Fields BS . Int J Microbiol 2012 2012 218791 Members of the Gram-negative genus Legionella are typically found in freshwater environments, with the exception of L. longbeachae, which is present in composts and potting mixes. When contaminated aerosols are inhaled, legionellosis may result, typically as either the more serious pneumonia Legionnaires' disease or the less severe flu-like illness Pontiac fever. It is presumed that all species of the genus Legionella are capable of causing disease in humans. As a followup to a prior clinical study of legionellosis in rural Thailand, indigenous soil samples were collected proximal to cases' homes and workplaces and tested for the presence of legionellae by culture. We obtained 115 isolates from 22/39 soil samples and used sequence-based methods to identify 12 known species of Legionella represented by 87 isolates. |
Eight years of Legionnaires' disease transmission in travellers to a condominium complex in Las Vegas, Nevada
Silk BJ , Moore MR , Bergtholdt M , Gorwitz RJ , Kozak NA , Tha MM , Brown EW , Winchester JL , Labus BJ , Rowley P , Middaugh JP , Fields BS , Hicks LA . Epidemiol Infect 2012 140 (11) 1-10 SUMMARY: Travel is a risk factor for Legionnaires' disease. In 2008, two cases were reported in condominium guests where we investigated a 2001 outbreak. We reinvestigated to identify additional cases and determine whether ongoing transmission resulted from persistent colonization of potable water. Exposures were assessed by matched case-control analyses (2001) and case-series interviews (2008). We sampled potable water and other water sources. Isolates were compared using sequence-based typing. From 2001 to 2008, 35 cases were identified. Confirmed cases reported after the cluster in 2001-2002 were initially considered sporadic, but retrospective case-finding identified five additional cases. Cases were more likely than controls to stay in tower 2 of the condominium [matched odds ratio (mOR) 6.1, 95% confidence interval (CI) 1.6-22.9]; transmission was associated with showering duration (mOR 23.0, 95% CI 1.4-384). We characterized a clinical isolate as sequence type 35 (ST35) and detected ST35 in samples of tower 2's potable water in 2001, 2002, and 2008. This prolonged outbreak illustrates the importance of striving for permanent Legionella eradication from potable water. |
Virulence factors encoded by Legionella longbeachae identified on the basis of the genome sequence analysis of clinical isolate D-4968
Kozak NA , Buss M , Lucas CE , Frace M , Govil D , Travis T , Olsen-Rasmussen M , Benson RF , Fields BS . J Bacteriol 2009 192 (4) 1030-44 Legionella longbeachae causes most cases of legionellosis in Australia and may be under-reported worldwide due to the lack of L. longbeachae-specific diagnostic tests. L. longbeachae displays distinctive differences in intracellular trafficking, caspase-1 activation, and infection of mouse models compared to L. pneumophila, yet both species have an indistinguishable clinical presentation in humans. Unlike other legionellae, which inhabit fresh water systems, L. longbeachae is found predominantly in moist soil. In this study, we sequenced and annotated the genome of a L. longbeachae clinical isolate, D-4968, from Oregon, US, and compared it to the published genomes of L. pneumophila. The study revealed that the D-4968 genome is larger with a gene order that is different from L. pneumophila. Genes encoding structural components of type II, type IV Lvh, and type IV Icm/Dot secretion systems are conserved. In contrast, only 42/140 homologs of L. pneumophila Icm/Dot substrates have been found in the D-4968 genome. L. longbeachae encodes numerous proteins with eukaryotic motifs and eukaryotic-like proteins unique to this species, including 16 ankyrin repeat-containing proteins and a novel U-box protein. We predict that these proteins are secreted by the L. longbeachae Icm/Dot secretion system. In contrast to L. pneumophila, the L. longbeachae D-4968 genome does not carry flagellar biosynthesis genes, yet contains a chemotaxis operon. The lack of a flagellum explains the failure of L. longbeachae to activate caspase-1 and trigger pyroptosis in murine macrophages. These unique features of the L. longbeachae genome may reflect adaptation of this species to life in soil. |
Distribution of lag-1 alleles and sequence-based types among Legionella pneumophila serogroup 1 clinical and environmental isolates in the United States
Kozak NA , Benson RF , Brown E , Alexander NT , Taylor TH Jr , Shelton BG , Fields BS . J Clin Microbiol 2009 47 (8) 2525-35 Approximately 84% of legionellosis cases are due to Legionella pneumophila serogroup 1. Moreover, a majority of L. pneumophila serogroup 1 clinical isolates react positively with monoclonal antibody 2 (MAb2) of the international standard panel. Over 94% of the legionellosis outbreaks investigated by the Centers for Disease Control and Prevention are due to this subset of L. pneumophila serogroup 1. To date, there is no complete explanation for the enhanced ability of these strains to cause disease. To better characterize these organisms, we subtyped 100 clinical L. pneumophila serogroup 1 isolates and 50 environmental L. pneumophila serogroup 1 isolates from the United States by (i) reactivity with MAb2, (ii) presence of a lag-1 gene required for the MAb2 epitope, and (iii) sequence-based typing analysis. Our results showed that the MAb2 epitope and lag-1 gene are overrepresented in clinical L. pneumophila serogroup 1 isolates. MAb2 recognized 75% of clinical isolates but only 6% of environmental isolates. Similarly, 75% of clinical isolates but only 8% of environmental isolates harbored lag-1. We identified three distinct lag-1 alleles, referred to as Philadelphia, Arizona, and Lens alleles, among 79 isolates carrying this gene. The Arizona allele is described for the first time in this study. We identified 59 different sequence types (STs), and 34 STs (58%) were unique to the United States. Our results support the hypothesis that a select group of STs may have an enhanced ability to cause legionellosis. Combining sequence typing and lag-1 analysis shows that STs tend to associate with a single lag-1 allele type, suggesting a hierarchy of virulence genotypes. Further analysis of ST and lag-1 profiles may identify genotypes of L. pneumophila serogroup 1 that warrant immediate intervention. |
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