The effect of a honey based gel and silver sulphadiazine on bacterial infections of in vitro burn wounds

Bacterial contamination remains a constant threat in burn wound care. Topical treatments to combat contaminations have good bactericidal effects but can have detrimental effects for the healing process. Treatments with for example silver can increase healing times. Honey based products can be a good alternative as it is antibacterial and patient-friendly.     

Evaluation of biofilm production and characterization of genes encoding type III secretion system among Pseudomonas aeruginosa isolated from burn patients

Pseudomonas aeruginosa is one of the common pathogenic causes of serious infections in burn patients throughout the world. Type III secretion toxins are thought to promote the dissemination of P. aeruginosa from the site of infection, the bacterial evasion of the host immune response and inhibition of DNA synthesis leading to host cell death. A total of 96 isolates of P. aeruginosa were collected from wound infections of burn patients, from April to July 2010. Antimicrobial susceptibility of the isolates were determined by disk agar diffusion method. Polymerase chain reaction (PCR)-based method was used for targeting the genes encoding the type III secretion toxins.     

Comparison of pathogens and antibiotic resistance of burn patients in the burn ICU or in the common burn ward

Background

This study aims to compare pathogens and their antibiotic resistances of burn patients from burn intensive care unit (ICU) or common burn ward. Of 2395 clinical samples from 63 patients in burn ICU, pathogens were detected in 1621 samples, in which 1203 strains (74.2%) were Gram negative bacteria, 248 strains (15.3%) were Gram positive bacteria, 170 strains (10.5%) were fungi. Top-4 microorganisms isolated from patients in burn ICU were Bauman's Acinetobacter (557, 34.4%), Pseudomonas aeruginosa (287.17.7%), Staphylococcus aureus (199, 12.3%) and Klebsiella pneumoniae (171, 10.5%). Of 512 clinical samples from 235 patients in common burn units, pathogens were detected in 373 samples, in which 189 (50.6%) strains were Gram negative bacteria, 150 strains (40.2%) were Gram positive bacteria, 34 strains (9.2%) were fungi. Top-4 microorganisms isolated from patients in common burn units were S. aureus (103, 27.6%), P. aeruginosa (46, 12.3%), K. pneumoniae (38, 10.2%) and Escherichia coli (32, 8.6%). Antibiotic resistance rates of pathogens isolated from clinical samples of burn patients from ICU was significantly higher than those from common units.

Conclusions

Pathogens and their antibiotic resistances are significantly different between burn ICU and common burn units. This finding has great implication for infection control in burn patients.     

Anoxia inhibits biofilm development and modulates antibiotic activity

Background

Many infections involve bacterial biofilms that are notoriously antibiotic resistant. Unfortunately, the mechanism for this resistance is unclear. We tested the effect of oxygen concentration on development of Staphylococcus aureus biofilms, and on the ability of gentamicin and vancomycin to inhibit biofilm development.

Materials and methods

To mimic catheter-associated biofilms, silastic coupons were inoculated with 10⁷S aureus and incubated either aerobically (∼21% O₂) or anaerobically (10% CO₂, 5% H₂, 85% N₂) for 16 h at 37°C with varying concentrations of gentamicin and vancomycin. Viable colony-forming units were quantified from sonicated biofilms, and the crystal violet assay quantified biofilm biomass. Metabolomic profiles probed biochemical differences between aerobic and anaerobic biofilms.

Results

Control biofilms (no antibiotic) cultivated aerobically contained 8.1–8.6 log₁₀S aureus. Anaerobiasis inhibited biofilm development, quantified by viable bacterial numbers and biomass (P < 0.05). Bactericidal concentrations of gentamicin inhibited biofilm development in normoxia but not anoxia, likely because bacterial uptake of gentamicin is oxygen dependent. The inhibitory effect of vancomycin was more uniform aerobically and anaerobically, although at high bactericidal concentrations, vancomycin effectiveness was decreased under anoxia. There were notable differences in the metabolomic profiles of biofilms cultivated under normoxia versus anoxia.

Conclusions

Compared with aerobic incubation, anaerobiasis resulted in decreased biofilm development, and metabolomics is a promising tool to identify key compounds involved in biofilm formation. The effectiveness of a specific antibiotic depended on its mode of action, as well as on the oxygen concentration in the environment.     

Prevention of Staphylococcus aureus burn wound colonization by nasal mupirocin

BACKGROUND: There are two important routes for the transmission of Staphylococcus aureus to the burn wound. In the endogenous route, patients naturally carrying S. aureus colonize their own wounds, whereas in the exogenous route burn wounds are cross-infected from other sources. In this study we evaluated the effect of blocking the endogenous route on S. aureus burn wound colonization by mupirocin application in the nose of patients at the time of admission. METHODS: From September 2000 to January 2002 all patients with burns admitted to a single dedicated Burn Centre received nasal mupirocin upon admission. This period was compared to two control periods (C1: July 1999 to July 2000 and C2: January 2002 to January 2003) for S. aureus burn wound colonization. The colonization risk was analysed, adjusting for confounding, with Cox proportional hazard regression. RESULTS: A total of 98 patients did not have S. aureus burn wound colonization at the time of admission and were, thus, considered at risk for S. aureus acquisition during their stay. As compared to C1, the relative risk of acquiring S. aureus in their wound was 0.48 (95% CI: 0.24-0.97) in the mupirocin period and 0.55 (95% CI: 0.28-1.1) during the C2 period. S. aureus nasal/pharyngeal colonization was a significant independent risk factor for wound colonization (RR: 2.3; 95% CI: 1.2-4.2). CONCLUSION: Nasal mupirocin may contribute to risk reduction of S. aureus wound colonization in patients with burns.     

Passive immunisation against Pseudomonas aeruginosa recombinant flagellin in an experimental model of burn wound sepsis

Background

This study was aimed to investigate whether anti-recombinant flagellin type A (anti r-fla-A) immunoglobulin G (IgG) provides protection in a mouse burn model of infection, and to determine the role of anti r-fla-A IgG as an opsonin and motility inhibitor in local and systemic infections.

Methods

Following the preparation of r-flagellin type A, rabbit polyclonal IgG was prepared. Specificity of anti r-flagellin for r-flagellin was evaluated by immunoblot analysis. After burn and challenge, mortality rate was screened in the mice treated with anti r-fla-A IgG. The ability of antiserum to promote phagocytosis of bacteria was assessed by the opsonophagocytosis testing. Functional activity of anti r-fla-A IgG was assessed in vitro by motility inhibition assay. Bacterial quantity in skin and internal organs was evaluated to study systemic infection.

Results

In vivo administration of anti r-fla-A IgG resulted in a significant improvement in survival in mice infected by a homologous strain of Pseudomonas aeruginosa from 16.6% to 75% compared with the control IgG. By contrast, this rate was 33.3% in the mice infected by the heterologous strain, PAO1 (type B flagellated strain). Protection was improved by giving a second treatment of r-flagellin antisera at 24-h post-burn and infection. Furthermore, anti r-fla-A IgG enhanced considerably the phagocytosis of the homologous strain but it was slight in the heterologous strain. The antiserum against r-flagellin type A was able to inhibit the motility of the PAK strain (type A flagellated strain), but slight inhibition was observed against PAO1. Meanwhile, anti r-fla-A IgG inhibited the systemic spread of PAK strain from the site of infection to internal organs.

Conclusion

In this study, passive immunisation with anti r-fla-A IgG was active against a homologous strain of infecting P. aeruginosa, but lost most of its efficiency against a heterologous strain. Therefore, passive treatment with anti r-fla-A IgG might protect burned mice against local and systemic infection of P. aeruginosa.     

Evaluations of bacterial contaminated full thickness burn wound healing in Sprague Dawley rats Treated with Tualang honey

Aim:

The effect of Tualang honey on wound healing in bacterial contaminated full-thickness burn wounds was evaluated in 36 male Sprague Dawley rats.

Materials and Methods:

The rats were randomly divided into three groups (n = 12/group). Three full-thickness burn wounds were created on each rat. Each group of rats was inoculated with a different organism in the burn wounds: Group A was inoculated with Pseudomonas aeruginosa, Group B was inoculated with Klebsiella pneumoniae and Group C was inoculated with Acinetobacter baumannii. One wound on each rat was dressed with either Tualang honey, Chitosan gel or Hydrofibre silver. Each wound size was measured on day 3, 6, 9, 12, 15, 18 and 21 of the study.

Results:

The mean wound size of the Tualang honey-treated wounds was not statistically different than that of the Chitosan gel or Hydrofibre silver-treated wounds when the wounds were compared throughout the entire experiment (P > 0.05). However, comparing the mean wound size on day 21 alone revealed that the Tualang honey-treated wounds were smaller in comparison to that of the Chitosan gel and Hydrofibre silver-treated groups.

Conclusions:

This study shows that topical application of Tualang honey on burn wounds contaminated with P. aeruginosa and A. baumannii gave the fastest rate of healing compared with other treatments.     

Twenty-five year epidemiology of invasive methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered at a burn center

Over the past two decades, an epidemiologic emergence of methicillin-resistant Staphylococcus aureus (MRSA) infections has occurred from that of primarily hospital-associated to community-associated. This emergence change has involved MRSA of different pulsed-field types (PFT), with different virulence genes and antimicrobial resistance patterns. In this study we, evaluate the changes in PFT and antimicrobial resistance epidemiology of invasive MRSA isolates over 25 years at a single burn unit. Isolates were tested by pulsed-field gel electrophoresis (PFGE), broth microdilution antimicrobial susceptibility testing, and PCR for the virulence factors Panton–Valentine leukocidin (PVL) and arginine catabolic mobile element (ACME), and the resistance marker staphylococcal chromosomal cassette mec (SCCmec). Forty isolates were screened, revealing stable vancomycin susceptibility MIC without changes over time but decreasing susceptibility to clindamycin and ciprofloxacin. The majority of PFGE types were MRSA USA800 carrying the SCCmec I element and USA100 carrying the SCCmec II element. No strains typically associated with community-associated MRSA, USA300 or USA400, were found. USA800 isolates were predominately found in the 1980s, USA600 isolates were primarily found in the 1990s, and USA100 isolates were found in the 2000s. The PVL gene was present in only one isolate, the sole USA500 isolate, from 1987. The virulence marker ACME was not detected in any of the isolates. Overall, a transition was found in hospital-associated MRSA isolates over the 25 years, but no introduction of community-associated MRSA isolates into this burn unit. Continued active surveillance and aggressive infection control strategies are recommended to prevent the spread of community-acquired MRSA to this burn unit.     

Therapy with anti-flagellin A monoclonal antibody limits Pseudomonas aeruginosa invasiveness in a mouse burn wound sepsis model

Background

The aim of this study was to evaluate the effect of an anti-flagellin sub-type monoclonal antibody (anti-fla-a) on Pseudomonas aeruginosa infection in a mouse burn model and to assay bacterial dissemination and invasiveness.

Methods

After immediate post-burn infection with P. aeruginosa, mortality and morbidity (daily weight changes) were monitored in mice treated with anti-fla-a as compared to untreated mice. Bacterial dissemination and invasiveness were monitored by bacterial counts at the burn site and spleen. Three different timing regimens for anti-fla-a treatment were studied: (a) prophylaxis (pre-infection), (b) therapeutic (post-infection), and (c) combined mode.

Results

Combined regimen of anti-fla-a markedly improved survival of mice infected with P. aeruginosa from 6% to 96% (p < 0.0001), similar to treatment with Imipenem. Furthermore, a significant improvement in survival was obtained when anti-fla-a was given prior to (75% survival) or post-infection (50% survival). It reduced bacterial load in the spleen (p = 0.01), preventing bacterial sepsis.

Conclusion

Anti-fla-a is effective in reducing mortality and morbidity in murine P. aeruginosa-infected burn model.     

Risk factors for acquisition of Methicillin-resistant Staphylococcus aureus among patients from a burn unit in Brazil

Methicillin-resistant Staphylococcus aureus (MRSA) is an important agent of colonization and infection in burn units. In order to identify risk factors for MRSA acquisition in a Brazilian burn unit, we performed two retrospective studies. In the first (“cohort” study), 175 patients who were not colonized with MRSA on admission were followed to assess risk factors for MRSA acquisition. In the second (“case–case–control” study), 143 individuals from the previous study who were negative for both MRSA and Methicillin-susceptible S. aureus (MSSA) on admission were followed. Case–control studies were performed to investigate risk factors for MRSA and MSSA acquisition. MRSA and MSSA were recovered from 75 and 23 patients, respectively. In the “cohort” study, only the number of wound excisions (Odds Ratio [OR] = 1.55, 95% Confidence Interval [CI] = 1.21–1.98, P = 0.001) was associated with MRSA acquisition. In the “case–case–control” study, burns involving head (OR = 3.43, 95%CI = 1.50–7.81, P = 0.003) and the number of wound excisions (OR = 1.83, 95%CI = 1.27–2.63, P = 0.001) were significant risk factors for MRSA. Burns involving perineum were negatively associated with MSSA acquisition (OR = 0.16, 95%CI = 0.03–0.75, P = 0.02). In conclusion, the acquisition of MRSA was related to the site of the burn and to the surgical manipulation of tissues, but not to the use of antimicrobials.     

Endocarditis in burn patients: clinical and diagnostic considerations

BACKGROUND: Burned patients are at high risk for invasive procedures, bacteremia, and other infectious complications. Previous publications describe high incidence, delayed diagnosis, and high mortality for endocarditis in burned patients, but do not address use of contemporary diagnostic criteria. Further analysis of the clinical presentation and diagnosis may aid in the earlier recognition and decreased mortality of endocarditis in burned patients. METHODS: At a 40 bed burn center, during the period from 1 January 2003 to 1 August 2006, blood culture, electronic inpatient, echocardiographic, and autopsy records were reviewed for cases of endocarditis and persistent bacteremia (blood culture positivity for the same organism separated by 24h). In addition, we reviewed cases of burn-related bacterial endocarditis published in the English language. We compared the clinical and diagnostic aspects of our identified cases with those in the published literature. RESULTS: There were 90 episodes of persistent bacteremia or fungemia in 56 of 1250 patients admitted during the study period. Echocardiography was performed on 19, identifying 4 cases of endocarditis. One additional case of endocarditis was identified post-mortem. Time until echocardiography ranged from 6 to 176 days after onset of bacteremia. Case patient age ranged from 31 to 64 years, and total burn surface area ranged from 34 to 80%. Endocarditis occurred in 0.4% of burn unit admissions and in 8.9% of these patients with persistent bacteremia. Sites involved included the mitral valve (3), tricuspid valve (2), aortic valve (1), and pulmonic valve (1). Pathogens included Staphylococcus aureus, Pseudomonas aeruginosa, and one case of Enterococcus faecium. Diagnostic clues were minimal. Case mortality was 100%. A literature review revealed 17 publications describing confirmed bacterial endocarditis in burned patients. These cases revealed a predilection for infection by S. aureus and P. aeruginosa, a relative paucity of diagnostic clues prior to death, and a trend towards ante-mortem diagnosis and increased survival with use of diagnostic echocardiography. CONCLUSIONS: The incidence and mortality of endocarditis in burned patients remain high. Clinical clues for endocarditis in this cohort are minimal and diagnosis may be delayed. For burned patients with persistent bacteremia, especially S. aureus or P. aeruginosa of unknown source, the diagnosis of endocarditis should be entertained and early echocardiography considered.     

Characterisation of SCCmec elements in methicillin-resistant Staphylococcus aureus isolated from burn patients

Staphylococcus aureus is an important pathogen, especially in burn units all around the world. Because of the emergence of the β-lactam antibiotic-resistant strains since 1961, concern about the prevalence of methicillin-resistant S. aureus (MRSA) has increased in these units. Resistance to methicillin is mediated by penicillin-binding proteins (PBPs) that have enough affinity for binding to the β-lactam ring, but another kind of protein (PBP2α), which is encoded by the mecA gene, has a lower affinity for binding to these antibiotics. The mecA gene is transferred by SCCmec (staphylococcal cassette chromosome mec) as a mobile genetic element, exclusively found in the Staphylococcus genus. Identification of the frequency of the mecA gene, different SCCmec types and also its incidence may have benefit in surveillance prevention and control of MRSA strains in burn units. In this study, 40 S. aureus isolates were collected from patients hospitalised in Motahari burn center of Tehran, during 2012–2013. Conventional microbiological methods were applied and the confirmed isolates were stored at −20 °C for molecular polymerase chain reaction (PCR) tests. The antibiotic resistance pattern was performed by disc diffusion method and finally the different SCCmec types were determined by specific primers. During this research, 40 isolates of S. aureus were collected from burn patients, of which (37.5%) of the specimens belonged to female patients and 62.5% to male patients. The aetiology of the burn was classified as follows: open flame (35%), liquid (32.5%), chemical (5%) and other (27.5%). By a disc diffusion method, no resistance pattern was observed to vancomycin and fosfomycin. Based on a multiplex PCR assay, the five different SCCmec types were detected as: 47.5% type III, 25% type IV, 10% type V, 10% type II and 7.5% type I.     

Molecular epidemiologic analysis of Staphylococcus aureus isolated from four burn centers

Staphylococcus aureus has been a major cause of hospital-acquired infections. Methicillin-resistant Staphylococcus aureus (MRSA) has emerged since 1980s as an epidemiologic problem in hospitals. This old pathogen brings a new challenge to all physicians and bacteriologists. Hence, effective measures of MRSA control are in critical need. S. aureus or MRSA is one of the leading causes of infection among burn centers, resulting in a number of poor outcomes and even death. The present study performed a molecular epidemiologic analysis of S. aureus isolated from four burn centers in the southeast of China. A total of 85 isolates were collected, and molecular characters were determined for further investigation. In this study, the prevalent clone of MRSA among four burn centers was found to be SCCmec III (spa-type t030, agr I), which is resistant to 4 kinds of antimicrobials including erythromycin, clindamycin, kanamycin and mupirocin. Discrepancy between mecA detection and conventional tests used for MRSA identification was observed unintentionally. Our data demonstrated that the overall prevalence rate of MRSA was 55.3%, and drugs such as sulfamethoxazole/trimethoprim, linezolid and fusidic acid are efficient antibiotic options for treating S. aureus or MRSA infections among four burn centers studied in present investigation.     

Inhibition of proliferation of Pseudomonas aeruginosa by KGF in an experimental burn model using human cultured keratinocytes

Experimental models showed the ability of Pseudomonas aeruginosa to interact with epidermal keratinocytes [Green H, Kehinde O, Thomas J. Growth of cultured human epidermal cells into multiple epithelia suitable for grafting. Proc Natl Acad Sci USA 1979;76(11):5665-8], stimulating these cells to produce specific peptides that start an immunological chain reaction in the epidermis [O'Connor NE, Mulliken JB, Banks-Schlegel S, Kehinde O, Green H. Grafting of burns with cultured epithelium prepared from autologous epidermal cells. Lancet 1981;(1):75-8]. The immune reaction causes the release of cytokines and growth factors. The objective of this study was to test whether the presence of keratinocyte growth factor (KGF) alters P. aeruginosa proliferation in an experimental burn model. METHODS: Human keratinocytes derived from neonatal foreskins were isolated and cultured following standard methods [Gallico III, GG, O'Connor NE, Compton CC, Kehinde O, Green H. Permanent coverage of large burn wounds with autologous cultured human epithelium. N Engl J Med 1984;311(7):448-51]. Some of these cells were genetically modified to produce KGF, and the other cells were supplemented with different KGF concentrations in the culture media. Both groups of keratinocytes were seeded in collagen matrices and cultured to form stratified epithelia. A hot plate was used to produce burn defects. Each matrix was inoculated with luminescent P. aeruginosa strain. Experiments were made using keratinocytes without KGF, keratinocytes supplemented with different concentrations of KGF, and keratinocytes genetically modified to produce KGF. Statistical analyses were made using Wilcoxon paired test. RESULTS: When KGF was added to P. aeruginosa in the presence of keratinocytes, bacterial growth was inhibited, and the same was observed when genetically modified keratinocytes were used. CONCLUSION: Many studies have been done on KGF, where its known properties were defined as a mitogen for keratinocytes [Munster AM. Cultured skin for massive burns: a prospective, controlled trial. Ann Surg 1996;224(3):372-7]. This method allows for a qualitative and quantitative evaluation in real time of the bacterial growth in wound sites after bacterial inoculation. KGF was involved in the reduction of bacterial viability. However, as KGF alone did not produce any effect on P. aeruginosa, it seems to modulate the skin innate immune response.     

In vitro efficacy of various topical antimicrobial agents in different time periods from contamination to application against 6 multidrug-resistant bacterial strains isolated from burn patients

Aim

In vitro efficacy evaluation of eleven topical antimicrobials against multidrug-resistant (MDR) bacteria isolated from burn wounds of our patients.

Material and methods

Growth of six MDR bacterial strains: Pseudomonas aeruginosa (2 strains), Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis and Escherichia coli in burn-wound models was evaluated 24-h after application of the tested agents. Four different wound models were created to investigate the role of time elapsed between inoculation of bacteria and application of the agents on their antimicrobial activity and efficacy.

Results

The efficacy against all the 6 bacteria in freshly contaminated wounds was excellent in majority of the tested agents. The longer was the time interval between inoculation and application of the topical antimicrobial agents, the higher failure of the agents was observed.

Conclusions

Topical antimicrobials play an important role in treatment of burn wounds, but they should be used according to their efficacy against bacterial strains present in patients’ wounds. In cases where topical agents have been applied after 24 h, when formation of mature biofilm in the wound could be expected, it would probably not be possible to kill all the bacteria using topical antimicrobial therapy only.     

An outbreak of a multiresistant methicillin-susceptible Staphylococcus aureus (MR-MSSA) strain in a burn centre: the importance of routine molecular typing

Here we report an outbreak among 17 patients caused by a single strain of a Multiresistant Methicillin-Susceptible Staphylococcus aureus (MR-MSSA) in a burn centre. The MR-MSSA strains were resistant to penicillin, ciprofloxacin, erythromycin, clindamycin and co-trimoxazole. Further analysis showed an increased prevalence of MR-MSSA carriership in S. aureus colonized patients admitted to the burn centre, from 0% in 2005 (0/118), 3.3% in 2006 (4/121), 6.1% in 2007 (6/99), to 7.8% in 2008 (7/90). Molecular typing with Amplified Fragment Length Polymorphism showed that all MR-MSSA isolates derived from burn centre patients had a unique genotype, and was different compared to isolates derived from other hospital patients. All healthcare workers (HCWs) who worked in the burn centre during the outbreak were screened for nasal carriage with MR-MSSA. One HCW tested positive for a genotype of MR-MSSA that was indistinguishable from the genotype found in samples of the burned patients. No new cases of MR-MSSA colonization or infection were identified after the colonized HCW stopped working at the burn centre. The routine practice of molecular typing of collected S. aureus strains from both patients and HCWs will help to detect nosocomial spread in a burn centre, and opens the possibility of a rapid, almost pre-emptive response.     

Susceptibility patterns and cross-resistance of antibiotics against Pseudomonas aeruginosa isolated from burn patients in the South of Iran

Pseudomonas aeruginosa plays a prominent role in serious infections in burn patients. Rapid acquisition of multi-drug resistance leads to high morbidity and mortality, especially in burn centers. Ten antibiotics, which were widely used in our burn patients were selected. MICs for imipenem, mropenem, cefepime, ceftazidime, cafoparazone/sulbactam, ticarcillin/clavulanate, piperacillin/tazobactam, ciprofloxacin, tobramycin and amikacin to 70 strains of P. aeruginosa, which were isolated from burn patients were determined by the E-test method (AB Biodisk, Sweden). Extended-spectrum beta-lactamase, group I inducible beta-lactamases and metallo-beta-lactamase activities were also determined. Imipenem and meropenum were the most active in vitro antibacterial agents followed by ciprofloxacin (p<0.05), whereas, ticarcillin/clavulanate was the least active. Almost all (98-100%) of the resistant isolates also showed cross-resistance to cefepime. The majority of imipenem and meropenem resistant isolates (85-100% and 76-100%) demonstrated cross-resistance to all the other antibiotics. ESBLs were detected in only three (4.3%) isolates, whereas, inducible beta-lactamase was observed in eight (11.4%) isolates. Metallo-beta-lactamase was detected in none of the isolates. Almost all of the antibiotic resistant isolates also showed cross-resistance to the majority of penicillins and cephalosporins with or without beta-lactamase inhibitors, from which ticarcillin/clavulanate demonstrated this phenomenon at the highest level.     

Genotyping of Pseudomonas aeruginosa strains isolated from burn patients by RAPD-PCR

Background

Pseudomonas aeruginosa is one of the important causes of nosocomial infections that easily gains resistance to many antibiotics. This opportunistic pathogen is a major health hazard particularly in immunodeficient patients, patients in intensive care units (ICU) and burn units with life threatening outcome. The bacterium may be originated from different or common sources, and comprises a high colonization and transmission capacity.

Objective

The aim of present study was to investigate the genotypic variation of Pseudomonas aeroginosa strains isolated from burn patients by using Random Amplified Polymorphic DNA (RAPD) method.

Methods

Totally 70 clinical samples were collected from burn patients in Taleghani Burn Hospital of Ahvaz. Fifty out of total samples were positive for P. aeruginosa by application of conventional culture and biochemical identification tests. DNA was extracted from the isolates and the RAPD-PCR method was applied to the DNA extracts according to standard method using a short single primer of 272. The technique created repetitive electrophoresis patterns which was used for genotypic differentiation.

Results

RAPD-PCR, created 9 genotypic profiles designated as I–IX with base pair length ranging from 180 to 2700. Each genotype showed between 3 and 6 different weight DNA bands. Genotype I was the most prevalent, identified in 10 bacterial isolates (20%). Genotypes I, II and VI were mostly common in patients with more severe burn, and were mainly isolated from wound and blood samples obtained from the same patients.

Conclusion

In present study, we found RAPD-PCR technique as a useful tool for investigation of the genetic variation among P. aeruginosa strains. This is a rapid, low cost, genotypic method with high discriminatory power. The results could assist to screen for the original of infection caused by this organism with subsequent control of colonization and transmission.