Comparison of respiratory activity and culturability during monochloramine disinfection of binary population biofilms

Stewart, Philip S.; Griebe, Thomas; Srinivasan, Rohini; Chen, C I; Yu, Feipeng Philip; Beer, Dirk de; McFeters, Gordon A.

doi:10.1128/aem.60.5.1690-1692.1994

Cited by 59 publications

(35 citation statements)

References 17 publications

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“…Bacteria growing in biofilms can remain in DWDS because they are resistant to the levels of disinfectant residuals present in the water (LeChevallier et al 1988;Stewart et al 1994). We used the Kadouri drip-fed reactor (Merritt et al 2005) in order to study the effect of chloramine on the resident cells in our DWDS biofilms, not to study biofilm-specific resistance to chloramine.…”

Section: Discussionmentioning

confidence: 99%

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Chloraminated drinking water does not generate bacterial resistance to antibiotics in Pseudomonas aeruginosa biofilms

Jurgens

Sattar

Mah

2008

Lett Appl Microbiol

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Aim: To determine if exposure of Pseudomonas aeruginosa biofilms to chloraminated drinking water can lead to individual bacteria with resistance to antibiotics. Methods and Results: Biofilms of P. aeruginosa PA14 were grown in drinking water in a Kadouri drip‐fed reactor; the biofilms were treated with either 0·5 mg l‐1 or 1·0 mg l‐1 of chloramine for 15 or 21 days; control biofilms were grown in water without chloramine. Fewer isolates with antibiotic resistance were obtained from the chloramine‐treated biofilms as compared to the control. Minimum inhibitory concentrations (MIC) for selected antibiotic‐resistant isolates were determined using ciprofloxacin, tobramycin, gentamicin, rifampicin and chloramphenicol. All of the isolates tested had increased resistance over the wildtype to ciprofloxacin, rifampicin and chloramphenicol, but were not resistant to tobramycin or gentamicin. Conclusions: Under these test conditions, there was no detectable increase in antibiotic resistance in P. aeruginosa exposed as biofilms to disinfectant residues in chloraminated drinking water. Significance and Impact of the study: Chloramine in drinking water, while unable to kill biofilm bacteria, does not increase the potential of P. aeruginosa to become resistant to antibiotics.

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Section: Discussionmentioning

confidence: 99%

“…It also leaves a disinfectant residual in the distribution system while keeping the water relatively free from the taste and odour often associated with chlorination. While the disinfectant residual in DWDS may not kill the bacteria in biofilms (LeChevallier et al 1988;Stewart et al 1994), it can stress them chemically.…”

Section: Introductionmentioning

confidence: 99%

Chloraminated drinking water does not generate bacterial resistance to antibiotics in Pseudomonas aeruginosa biofilms

Jurgens

Sattar

Mah

2008

Lett Appl Microbiol

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“…In the case of E. coli with peracetic acid, this represented a 20-fold reduction in susceptibility. PHMB and peracetic acid are chemically more reactive than the other agents and are therefore most likely to be subject to reactiondiffusion limitation within the bacterial glycocalyx (Stewart et al 1994). Changes in susceptibility, however, may be related to both attachment and biofilm formation.…”

Section: Formation Of Biofilm In the Presence Of Antimicrobial Agentmentioning

confidence: 99%

Changes in the biocide susceptibility of Staphylococcus epidermidis and Escherichia coli cells associated with rapid attachment to plastic surfaces

et al. 1998

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GI LB E RT . 1998. Differences in opacity between wells of a microtitre plate containing different volumes of inoculated growth medium reflected planktonic growth without any contribution from cells attached at the well surface. Simple algebra and a knowledge of the dependence of optical density upon sample path length (volume) for suspensions of differing cell density enables the generation of growth curves for attached populations (biofilms). In this manner, minimum inhibitory concentrations (MICs) were determined at various stages of growth (0-20 h), both for cells growing attached to the bases of the plate wells and, simultaneously, for cells growing in suspension above them. Biocides included cetrimide, polyhexamethylene biguanide, peracetic acid, phenoxyethanol and chloroxylenol. Results, expressed as planktonic:biofilm MIC ratios, showed susceptibility to change, not only as a function of attachment and biofilm formation, but also with respect to the nature of the chemical agent. In some instances, changes in susceptibility greater than twofold occurred immediately on attachment and could occur in the presence of biocide concentrations which exceeded the MIC.

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“…The mechanisms associated with such resistance are complex. These mechanisms involve not only the reaction-diffusion limitation of biocide-access to the underlying cells (Stewart 1994;Stewart et al 1994;Huang et al 1995), but also the expression of spatially heterogenous, less susceptible phenotypes, caused either by growth as a bio®lm per se (Brown et al 1988;Gilbert et al 1990a) or through the expression of high cell density (Davies et al 1998), or starvation, phenotypes (Foley et al 1999). Whilst there have been many publications that support the assertion of bio®lm recalcitrance, there have been few studies made which generate kinetic data that is capable of systematic evaluation of the relative extent of this phenomenon across a range of chemical biocides.…”

Section: Introductionmentioning

confidence: 99%

Assessment of resistance towards biocides following the attachment of micro-organisms to, and growth on, surfaces

et al. 2001

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Aims: To develop a rapid method for the assessment of biocidal activity directed towards intact bio®lms. Methods and Results: Escherichia coli and Staphylococcus epidermidis were cultured for up to 48 h within 96-well microtitre plates. The planktonic phase was removed and the wells rinsed. Residual bio®lms were exposed to various concentrations of chloroxylenol, peracetic acid, polyhexamethylene biguanide (PHMB), cetrimide or phenoxyethanol for 1 h. At 15-min intervals, biocide was removed, and the wells washed in neutraliser and ®lled with volumes of fresh medium. Re-growth of the cultures was monitored during incubation at 35°C in the plate reader. Times taken for the treated wells to re-grow to ®xed endpoints were determined and related to numbers of surviving cells. Time±survival curves were constructed and the survival of the attached bacteria, following exposure to the agents for 30 min, interpolated for each biocide concentration. Log±log plots of these survival data and biocide concentration were constructed, and linear regression analysis performed in order to (i) calculate concentration exponents and (ii) compare the effectiveness of the biocides between variously aged bio®lm and planktonic cells. From such analyses iso-effective concentrations of biocide (95% kill in 30 min) were calculated and expressed as planktonic : bio®lm indices (PBI). Conclusions: PBI varied between 1á02 and 0á02, were relatively unaffected by age of the bio®lms but differed signi®cantly between organism and biocide. Notably those compounds with the higher activity against planktonic bacteria (PHMB and peracetic acid) were most prone to a bio®lm effect but remained the most effective of the agents selected. Signi®cance and Impact of the Study: The endpoint method proved robust, enabled the bactericidal effects of the biocides to be assessed against in-situ bio®lms, and was suitable for routine screening applications.

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Comparison of respiratory activity and culturability during monochloramine disinfection of binary population biofilms

Cited by 59 publications

References 17 publications

Chloraminated drinking water does not generate bacterial resistance to antibiotics in Pseudomonas aeruginosa biofilms

Chloraminated drinking water does not generate bacterial resistance to antibiotics in Pseudomonas aeruginosa biofilms

Changes in the biocide susceptibility of Staphylococcus epidermidis and Escherichia coli cells associated with rapid attachment to plastic surfaces

Assessment of resistance towards biocides following the attachment of micro-organisms to, and growth on, surfaces

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