Journal of Pathogens

Journal of Pathogens / 2012 / Article

Research Article | Open Access

Volume 2012 |Article ID 138389 | 5 pages |

Detection and Quantification of Legionella pneumophila from Water Systems in Kuwait Residential Facilities

Academic Editor: Kendra Rumbaugh
Received11 Apr 2012
Revised27 May 2012
Accepted30 May 2012
Published24 Jul 2012


The prevalence of Legionella pneumophilia in water systems of residential facilities in Kuwait was performed during the period from November 2007 to November 2011. A total of 204 water samples collected from faucets and showerheads in bathrooms (n = 82), taps in kitchens (n = 51), and water tanks (n = 71), from different locations of residential facilities in Kuwait were screened for Legionella pneumophila by the standard culture method and by real time polymerase chain reaction (RT-PCR). Out of the 204 samples, 89 (43.6%) samples were positive for Legionella spp., 48 (23.5%) samples were detected by the standard culture method, and 85 (41.7%) were detected by RT-PCR. Of the culture positive Legionella samples, counts ranged between 10 to 2250 CFU/L. Serological typing of 48 Legionella isolates revealed that 6 (12.5%) of these isolates belonged to Legionella pneumophila serogroup 1, 37 (77.1%) isolates to Legionella pneumophila serogroup 3, and 1 isolate each (2.1%) belonged to serogroups 4, 7, and 10. The minimum inhibitory concentration (MICs) of the 46 environmental L. pneumophila isolates against the 10 antimicrobials commonly used for Legionella infection treatments were determined. Rifampicin was found to be the most active against L. pneumophila serogroups isolates in vitro.

1. Introduction

Outbreaks of Legionnaires’ disease have been worldwide traced to a wide variety of environmental water sources such as cooling towers, hot tubs, showerheads, whirlpools and spas, and public fountains [1, 2]. Legionella pneumophila serogroup 1 is responsible for up to 80% of Legionnaires’ disease reported cases [3, 4]. The potential health risk of Legionella to humans is theoretically associated with cells densities above 104 to 105 CFU per liter of water [5, 6].

Commonly used method for environmental surveillance of Legionella is the standard culture technique [7, 8]. Although the standard culture method allows the isolation and the quantification of Legionella from the environment, it does have its limitations: it requires selective media and prolonged incubation periods; bacterial loss can occur during the concentration stage followed by decontamination with heat or acid; interference of background organisms with Legionella growth may lead to an underestimation of the real number of Legionella present in the sample; Legionella spp. may enter a viable but noncultivable state, making it difficult to culture from water samples [9].

Recently, rapid and sensitive alternative methods have been found to be attractive alternatives to the conventional culture method for the detection of slow-growing and fastidious bacteria such as Legionella. These methods are PCR-based methods for the detection and quantification of Legionella in water that has been used primarily against the 5S and 16S rRNA genes and against the macrophage infectivity potentiator (mip) gene of L. pneumophila [1015]. A real-time-PCR-based method for rapid detection and quantification of Legionella in water samples have been developed [1517]. Several commercial real-time PCR kits are now available, and the main differences among these kits are based on the degrees of standardization of the three critical steps: DNA extraction, PCR preparation, and data analysis. However, all the PCR-based methods lack the ability to discriminate between living and nonliving (noninfectious) Legionella cells.

Despite the fact that environmental Legionella monitoring is recommended in several countries, in Kuwait, environmental monitoring of Legionella is not conducted and no active surveillance program exists. Moreover, research related to Legionella is scarce [1820]. Furthermore, no reports are available on the current status of the prevalence of Legionnaires’ disease and associated cases in Kuwait. However, annual reports presented by the Ministry of Planning show that the death of a percentage of the population (27.6/104 of population) is due to respiratory diseases without specifying the etiological agent [21].

Due to the following factors, it is likely that the prevalence of Legionella is underestimated; Kuwait’s a hot temperate climate; the absence of water safety regulations for Legionella monitoring and decontamination; and the increased use of cooling towers within recreational and health care facilities may increase the risk of legionellosis. In addition, water temperatures in water tanks during the summer in residential compounds may be favorable for Legionella multiplication (50°C). Owing to the possibility of environmental exposure to Legionella, this is the first study aimed at determining the prevalence of Legionella in selected residential facilities in Kuwait.

2. Material and Methods

2.1. Water Samples

A total of 204 samples were collected from November 2007 to November 2011. Water samples were obtained from faucets of wash basins and showerheads in bathrooms, taps ( 𝑛 = 8 2 ) from kitchens ( 𝑛 = 5 1 ) and cold/hot water tanks ( 𝑛 = 7 1 ), from different residential sites in the State of Kuwait. Water samples (1 L) were collected in a sterile 2 L plastic bottle containing 1mL of 0.1 N sodium thiosulfate to neutralize chlorine disinfectant.

2.2. Sample Concentration

The 1 L sample was filter concentrated in a biological safety cabinet by pouring the sample into a sterile 47 mm filter funnel assembly containing a 0.2 μm polycarbonate filter (Fisher Scientific, 3970 Johns Creek Ct., Suite 500, Suwanee, GA 30024). When the sample had passed through the filter, the filter was removed aseptically from the holder with sterile filter forceps, folded to the outside, and placed into a sterile, 50 mL centrifuge tube containing 10 mL of sterile water. Then, the centrifuge tube was vortexed for one minute to free bacteria and organic material from the filter and centrifuged at 3000  × g ± 100  × g for 30 min ± 1 min. Using a sterile graduated pipette aseptically, all but 1 mL of supernatant was carefully removed. The deposit was resuspended by vortex mixing. This constitutes the final concentrate that was stored in screw-capped containers at 6°C ± 2°C in the dark.

2.3. Standard Culture Method

From the final concentrate, 0.1 mL was inoculated onto buffered charcoal-yeast extract agar base (code CM0655; Oxoid; UK) with MWY selective supplement (code SR0118; Oxoid; UK), and 0.01 mL was inoculated onto BCYE agar with BMPA selective supplement (code SR0111; Oxoid; UK). Subsequently, 0.2 mL was heat treated at 50°C for 30 min, and 0.1 mL and 0.01 mL was inoculated onto MWY agar. Additionally, 0.2 mL of sample were acid treated in equal volume of HCl-KCl acid buffer (pH 2.2) for 5 min, and 0.1 mL was inoculated onto BMPA agar. All plates were incubated at 35°C in CO2 incubator. The plates were examined after 72 h to 96 h (4 to 7 d) incubation [22]. Suspect colonies were aseptically picked and streaked onto BCYE agar plate without L-cysteine [BCYE(−)]. Colonies that can grow on BCYE agar, but not BCYE(−) agar, were considered presumptive Legionella species.

2.4. Sero- and Subgrouping of Isolates

L. pneumophila isolates were first serogrouped with a Latex agglutination test commercial kit (code DR0800; Oxoid; UK) according to the manufacturer’s instructions. Further confirmation of serogroup was conducted with the Dresden panel of monoclonal antibodies [23].

2.5. Real-Time Quantitative PCR

Real-time PCR system (7500 Real time PCR system, Applied Biosystems; USA) and TaqMan Legionella pneumophila Detection Kits (Applied Biosystems P/N ED 000833; USA) were used for detection and quantification. All the samples were run with real-time PCR instrument using their DNA extracted from final concentrates using Clean Water DNA Extraction Kit (Applied Biosystems P/N ED 000849; USA) according to the manufacturer’s instructions.

2.6. Antimicrobial Susceptibility Testing

Susceptibility testing was performed for 10 antimicrobials using E-tests with the lowest available MIC range. The tested antimicrobials were Moxifloxacin, Cefotaxime, Tigecycline, Clarithromycin, Rifampicin, Azithromycin, Erythromycin, Levofloxacin, Doxycycline, and Ciprofloxacin. Antimicrobial susceptibility testing was carried out as described by Bruin et al., 2012 [24]. In brief, isolates were recultured for 2-3 days at 35°C with increased humidity. Colonies were then suspended in sterile water to a concentration of 107 CFU/mL and adjusted to 0.5 McFarland. A swab was then dipped in the suspension and used to inoculate a BCYE supplemented with ketoglutarate plates. The E test strip was then applied onto the swabbed surface, and the plates were then incubated at 35°C for 2 days with increased humidity. The MIC was read using a stereomicroscope from the scale of the strip at the point where the ellipse of growth inhibition intercepted the strip.

3. Results

A total of 204 water samples were collected from different locations of residential water supply facilities in Kuwait. All samples were tested by the standard culture method and by RT-PCR for the detection of L. pneumophila. Out of the 204 water samples tested, only 48 samples were positive by standard culture method (23.5%), whereas 85 (41.7%) samples were positive by RT-PCR (Table 1). This higher detection capabilities of real-time PCR compared to the culture method have been previously reported [2528].

Water sourcePCR+Culture+PCR+/culture+PCR+/culturePCR/culture+

Bathroom54.9% (45/82)a32.9% (27/82)30.5% (25/82)24.4% (20/82)2.4% (2/82)
Kitchen37.3% (19/51)29.4% (15/51)25.5% (13/51)11.8% (6/51)3.9% (2/51)
Water tanks29.6% (21/71)8.5% (6/71)8.5% (6/71)21.1% (15/71)0% (0/71)

Total41.7% (85/204)23.5% (48/204)22.1% (45/204)20.1% (41/204)2% (4/204)

a Number of positive samples/total number of samples.

The range (CFU/mL) of Legionella spp. and the prevalent serogroups isolated from water samples are shown in Table 2. Using the standard culture method, all positive samples showed count less than 104 CFU per liter, the upper limit that represents a potential health risk to humans [5, 6]. Serogrouping of the 48 Legionella isolates is also shown in Table 2. L. pneumophila accounted for all the isolated Legionella species. Among the 46 L. pneumophila isolates, the majority of the isolates belonged to serogroup 3 (37 isolates), followed by serogroup 1 (6 isolates), serogroup 7 (1 isolate), serogroup 10 (1 isolate), and serogroup 4 (1 isolate). All six isolates of serogroup 1 were of the OLDA/Oxford subgroup.

Source (n)Positive samples (n)Range (CFU/L)Total isolatesLegionella serogroups
Group 1Group 3Group 4Group 7Group 10L. species

Bathroom (45)PCR+/culture+ (25)10–2250273210012
PCR/culture+ (2)20–130
Kitchen (19)PCR+/culture+ (13)10–1250153101100
PCR/culture+ (2)10–30
Tank (21)PCR+/culture+ (6)10–5006060000
PCR/culture+ (0)

The susceptibility of the L. pneumophila isolates (MIC’s range mg/L) to 10 antimicrobials are shown in Table 3. In general, all isolates were inhibited by low concentrations of macrolides and fluoroquinolones. As an example, for serogroup 1, the minimum inhibitory concentration for the macrolides, MICs ranged from 0.19–0.25 for Erythromycin, 0.094–0.75 for Azithromycin, and 0.125–0.19 mg/L for Clarithromycin, respectively, while for the Fluoroquinolones MICs ranged from 0.38–0.5 μg/mL for Ciprofloxacin, 0.25–0.38 mg/L for Levofloxacin, and 0.50–1.0 mg/L for Moxifloxacin, respectively. The MIC for Rifampicin was determined to be 0.008–0.016, 0.047–0.38 for Cefotaxime, and 2-3 mg/L for Tigecycline, and 2 for Doxycycline, respectively. A similar susceptibility pattern was also observed for serogroup 3. The antimicrobial Rifampicin was found to be the most active of the antimicrobials against all L. pneumophila serogroups.

Serogroup 1
( 𝑛 = 6 )
Serogroup 3
( 𝑛 = 3 7 )
Serogroup 4
( 𝑛 = 1 )
Serogroup 7
( 𝑛 = 1 )
Serogroup 10
( 𝑛 = 1 )


4. Discussion

In this study, we examined the prevalence of Legionella pneumophila in the local residential water systems in the State of Kuwait. RT-PCR was carried out in parallel with the standard culture method in analyzing 204 water samples. Our results have shown that RT-PCR was more sensitive, less time consuming, and provides reproducible results making it more suitable as a screening assay to detect and quantify L. pneumophila in environmental water samples. However, PCR-based methods cannot differentiate between live and dead bacteria. Therefore, the culture method remains necessary for epidemiological comparison between clinical and environmental strains and to confirm an outbreak by PFGE analysis. Thus, quantitative real-time PCR would complement the reference standard culture method.

This study also showed the frequent isolation of L. pneumophila serogroup 3 as opposed to serogroup 1. Although the most frequent cause of legionnaires disease is Legionella serogroup 1, serogroup 3 has also been recently reported to cause community acquired and nosocomial pneumonia [29, 30]. Although the number of isolates was small in this study ( 𝑛 = 4 6 ), the predominance of L. pneumophila serogroup 3 from environmental samples may be useful in explaining the epidemiology of this serogroup in clinical and environmental outbreaks.

This study has also shown the antimicrobial susceptibility of all the isolate tested against antimicrobials often used to treat legionellosis. Macrolides are the most commonly used antimicrobial to treat legionellosis [31]. In particular, Rifampicin and the macrolides have demonstrated good activity against L. pneumophila serogroup 1 and 3. To our knowledge, this is the first survey on the prevalence and antimicrobial susceptibility of Legionella isolated from environmental water systems in residential facilities in the State of Kuwait.

5. Conclusion

Legionella is a common pathogenic colonizer of water distribution systems and cooling towers leading to severe health risks and considerable legal and economic damage to businesses. Although, environmental Legionella monitoring is recommended in several countries, in Kuwait, environmental Legionella is not being monitored. The study confirms the presences of L. pneumophila serogroup 1 and 3 in Kuwait’s domestic water systems with the most commonbeing L. pneumophila serogroup 3 (77.1%). The predominance of L. pneumophila serogroup 3 in water systems of residential facilities in Kuwait warrants further investigations to predict the risk that this serogroup plays in any future legionellosis outbreaks.


This research project was funded by Kuwait Institute for Scientific Research (KISR).


  1. R. M. Atlas, “Legionella: from environmental habitats to disease pathology, detection and control,” Environmental Microbiology, vol. 1, no. 4, pp. 283–293, 1999. View at: Google Scholar
  2. A. Doleans, H. Aurell, M. Reyrolle et al., “Clinical and environmental distributions of Legionella strains in France are different,” Journal of Clinical Microbiology, vol. 42, no. 1, pp. 458–460, 2004. View at: Publisher Site | Google Scholar
  3. J. H. Helbig, S. Bernander, M. Castellani Pastoris et al., “Pan-European study on culture-proven Legionnaires' disease: distribution of Legionella pneumophila serogroups and monoclonal subgroups,” European Journal of Clinical Microbiology and Infectious Diseases, vol. 21, no. 10, pp. 710–716, 2002. View at: Publisher Site | Google Scholar
  4. V. L. Yu, J. F. Plouffe, M. C. Pastoris et al., “Distribution of Legionella species and serogroups isolated by culture in patients with sporadic community-acquired legionellosis: an international collaborative survey,” Journal of Infectious Diseases, vol. 186, no. 1, pp. 127–128, 2002. View at: Publisher Site | Google Scholar
  5. M. Best, V. L. Yu, and J. Stout, “Legionellaceae in the hospital water-supply. Epidemiological link with disease and evaluation of a method for control of nosocomial legionnaires' disease and Pittsburgh pneumonia,” The Lancet, vol. 2, no. 8345, pp. 307–310, 1983. View at: Google Scholar
  6. J. L. Kool, D. Bergmire-Sweat, J. C. Butler et al., “Hospital characteristics associated with colonization of water systems by Legionella and risk of nosocomial Legionnaires' disease: a cohort study of 15 hospitals,” Infection Control and Hospital Epidemiology, vol. 20, no. 12, pp. 798–805, 1999. View at: Publisher Site | Google Scholar
  7. Association Francaise de Normalisation, “Testing water-detection and enumeration of Legionella et de Legionella pneumophila-general method by direct culture and membrane filtration,” French Standard AFNOR NF T90-431, Association Francaise de Normalisation, Paris, France, 1993. View at: Google Scholar
  8. International Standards Organization, “Water quality-detection and enumeration of Legionella,” International standard ISO, 11731, International Standards Organization (International Organization for Standardization), Geneva, Switzerland, 1998. View at: Google Scholar
  9. J. Hay, D. V. Seal, B. Billcliffe, and J. H. Freer, “Non-culturable Legionella pneumophila associated with Acanthamoeba castellanii: detection of the bacterium using DNA amplification and hybridization,” Journal of Applied Bacteriology, vol. 78, no. 1, pp. 61–65, 1995. View at: Google Scholar
  10. J. L. Cloud, K. C. Carroll, P. Pixton, M. Erali, and D. R. Hillyard, “Detection of Legionella species in respiratory specimens using PCR with sequencing confirmation,” Journal of Clinical Microbiology, vol. 38, no. 5, pp. 1709–1712, 2000. View at: Google Scholar
  11. M. Koide, A. Saito, N. Kusano, and F. Higa, “Detection of Legionella spp. in cooling tower water by the polymerase chain reaction method,” Applied and Environmental Microbiology, vol. 59, no. 6, pp. 1943–1946, 1993. View at: Google Scholar
  12. D. Lye, G. S. Fout, S. R. Crout, R. Danielson, C. L. Thio, and C. M. Paszko-Kolva, “Survey of ground, surface, and potable waters for the presence of Legionella species by EnviroAmpR PCR Legionella kit, culture, and immunofluorescent staining,” Water Research, vol. 31, no. 2, pp. 287–293, 1997. View at: Publisher Site | Google Scholar
  13. H. Miyamoto, H. Yamamoto, K. Arima et al., “Development of a new seminested PCR method for detection of Legionella species and its application to surveillance of Legionellae in hospital cooling tower water,” Applied and Environmental Microbiology, vol. 63, no. 7, pp. 2489–2494, 1997. View at: Google Scholar
  14. P. Villari, E. Motti, C. Farullo, and I. Torre, “Comparison of conventional culture and PCR methods for the detection of Legionella pneumophila in water,” Letters in Applied Microbiology, vol. 27, no. 2, pp. 106–110, 1998. View at: Google Scholar
  15. N. Wellinghausen, C. Frost, and R. Marre, “Detection of Legionellae in hospital water samples by quantitative real-time LightCycler PCR,” Applied and Environmental Microbiology, vol. 67, no. 9, pp. 3985–3993, 2001. View at: Publisher Site | Google Scholar
  16. A. L. Ballard, N. K. Fry, L. Chan et al., “Detection of Legionella pneumophila using a real-time PCR hybridization assay,” Journal of Clinical Microbiology, vol. 38, no. 11, pp. 4215–4218, 2000. View at: Google Scholar
  17. P. Joly, P. A. Falconnet, J. André et al., “Quantitative real-time Legionella PCR for environmental water samples: data interpretation,” Applied and Environmental Microbiology, vol. 72, no. 4, pp. 2801–2808, 2006. View at: Publisher Site | Google Scholar
  18. J. A. Qasem, A. S. Mustafa, and Z. U. Khan, “Legionella in clinical specimens and hospital water supply facilities: molecular detection and genotyping of the isolates,” Medical Principles and Practice, vol. 17, no. 1, pp. 49–55, 2008. View at: Publisher Site | Google Scholar
  19. N. Al-Terkait and A. Sadak, “A travel abroad-associated case of Legionella pneumonia,” Kuwait Medical Journal, vol. 38, pp. 59–60, 2006. View at: Google Scholar
  20. N. Behbehani, A. Mahmood, E. M. Mokaddas et al., “Significance of atypical pathogens among community-acquired pneumonia adult patients admitted to hospital in Kuwait,” Medical Principles and Practice, vol. 14, no. 4, pp. 235–240, 2005. View at: Publisher Site | Google Scholar
  21. Ministry of Planning, Annual Statistical Abstract, Central Statistical Bureau, State of Kuwait, 46th edition, 2009.
  22. AS/NZS 3896, Waters-Examination for Legionellae, Standards Australia, North Sydney, Australia, 1998.
  23. C. W. Svarrer, C. Luck, P. L. Elverdal, and S. A. Uldum, “Immunochromatic kits Xpect Legionella and BinaxNOW Legionella for detection of Legionella pneumophila urinary antigen have low sensitivities for the diagnosis of Legionnaires' disease,” Journal of Medical Microbiology, vol. 61, pp. 213–217, 2012. View at: Publisher Site | Google Scholar
  24. P. J. Bruin, E. P. F. Ijzerman, J. W. den Boer, J. W. Mouton, and B. M. W. Diederen, “Wild-type MIC distribution and epidemiological cut-off values in clinical Legionella pneumophila serogroup 1 isolates,” Diagnostic Microbiology and Infectious Disease, vol. 72, pp. 103–108, 2012. View at: Publisher Site | Google Scholar
  25. J. Behets, P. Declerck, Y. Delaedt, B. Creemers, and F. Ollevier, “Development and evaluation of a Taqman duplex real-time PCR quantification method for reliable enumeration of Legionella pneumophila in water samples,” Journal of Microbiological Methods, vol. 68, no. 1, pp. 137–144, 2007. View at: Publisher Site | Google Scholar
  26. K. Levi, J. Smedley, and K. J. Towner, “Evaluation of a real-time PCR hybridization assay for rapid detection of Legionella pneumophila in hospital and environmental water samples,” Clinical Microbiology and Infection, vol. 9, no. 7, pp. 754–758, 2003. View at: Publisher Site | Google Scholar
  27. F. Morio, S. Corvec, N. Caroff, F. Le Gallou, H. Drugeon, and A. Reynaud, “Real-time PCR assay for the detection and quantification of Legionella pneumophila in environmental water samples: utility for daily practice,” International Journal of Hygiene and Environmental Health, vol. 211, no. 3-4, pp. 403–411, 2008. View at: Publisher Site | Google Scholar
  28. D. F. Yaradou, S. Hallier-Soulier, S. Moreau et al., “Integrated real-time PCR for detection and monitoring of Legionella pneumophila in water systems,” Applied and Environmental Microbiology, vol. 73, no. 5, pp. 1452–1456, 2007. View at: Publisher Site | Google Scholar
  29. C. Tram, M. Simonet, M. H. Nicolas et al., “Molecular typing of nosocomial isolates of Legionella pneumophila serogroup 3,” Journal of Clinical Microbiology, vol. 28, no. 2, pp. 242–245, 1990. View at: Google Scholar
  30. A. Mencacci, C. Corbucci, A. Castellani, P. Furno, F. Bistoni, and A. Vecchiarelli, “Legionella pneumophila serogroup 3 pneumonia in a patient with low-grade 4 non-Hodgkin lymphoma: a case report,” Journal of Medical Case Reports, vol. 5, pp. 387–391, 2011. View at: Publisher Site | Google Scholar
  31. M. H. Nguyen, J. E. Stout, and V. L. Yu, “Legionellosis,” Infectious disease clinics of North America, vol. 5, no. 3, pp. 561–584, 1991. View at: Google Scholar

Copyright © 2012 Qadreyah A. Al-Matawah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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