The study on Pseudomonas aeruginosa infection in a hospital--2. Bacteriological study

We investigated the hospital acquired infection of P. aeruginosa in urological wards by determining the serotype and testing the sensitivity of this bacteria to antibiotics. The results were as follows: 1. 92 strains of G-serotype (22.2%), 76 of A-serotype (18.3%) and 65 of B-serotype (15.7%) were predominantly found in the serotype distribution of 415 P. aeruginosa strains isolated from urine or feces. 2. Comparing the sensitivity of P. aeruginosa to various antibiotics determined by MIC50 (the concentration to inhibit growth of 50% of the objective bacteria), Dibekacin showed MIC50 of 0.78 microgram/ml, Ceftazidime 1.56 micrograms/ml, Cefsulodin 3.13 micrograms/ml, and Polymixin-B, Piperacillin, Aztreonam 6.25 micrograms/ml. The analysis of the relationship between serotype and sensitivity to antibiotics demonstrated that K-serotype of P. aeruginosa tended to be highly sensitive and M-serotype be less sensitive to only Dibekacin. There was no definite relation of serotype to sensitivity against any other antibiotics. The comparison of sensitivity to antibiotics determined by MIC50,80 between P. aeruginosa isolated from urine and that from feces revealed that the former was less sensitive by one to four grades than the latter. The sensitivity of P. aeruginosa isolated from feces at admission was not different from that at discharge. In the chronological changes in sensitivity of P. aeruginosa isolated from urine, the strains highly resistant to Cefsulodin, Ceftazidime, Aztreonam and Dibekacin had increased in 1984 and 1985. 3. These highly resistant strains tended to break out in the urological wards, which suggested the need for more intensive prophylactic measures against hospital acquired infection.     

In-vitro and in-vivo activity of antimicrobial-coated prosthetic heart valve sewing cuffs

BACKGROUND AND AIM OF THE STUDY: Prosthetic valve endocarditis (PVE) is a relatively uncommon but very serious condition. As bacterial colonization of the prosthetic heart valve sewing cuff can be a prelude to the clinical occurrence of PVE, antimicrobial coating of the sewing cuff may be beneficial. The study aims were to examine the antimicrobial activity in vitro and anti-infective efficacy in vivo of prosthetic heart valve sewing cuffs coated with minocycline and rifampin. METHODS: Zones of inhibition by antimicrobial-coated sewing cuffs were assessed in vitro against Staphylococcus epidermidis, S. aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans. The ability of subcutaneously implanted devices coated with minocycline and rifampin to resist colonization and infection by P. aeruginosa was also examined in a rabbit model. RESULTS: Antimicrobial-coated sewing cuffs produced zones of inhibition against all tested organisms. Coated devices were significantly less likely than uncoated devices to become colonized (2/24; 8% versus 20/24; 83%; p <0.001) or to cause device-related infection (0/24; 0% versus 18/24; 75%; p <0.001) and device-related abscess (0/24; 0% versus 10/24; 42%; p <0.001) due to P. aeruginosa. CONCLUSION: Prosthetic heart valve sewing cuffs coated with minocycline and rifampin provide broad-spectrum antimicrobial activity in vitro, and are anti-infective in vivo against P. aeruginosa. These results encourage the clinical evaluation of these sewing cuffs.     

Outbreak of endocarditis caused by Pseudomonas aeruginosa serotype O11 among pentazocine and tripelennamine abusers in Chicago

At Cook County Hospital (Chicago), before 1977, the incidence of endocarditis caused by Pseudomonas aeruginosa was one or two cases per year. The frequency of P. aeruginosa as an etiologic agent of endocarditis among drug abusers increased steadily from five (23%) of 22 patients in 1977 to 15 (68%) of 22 in 1980. P. aeruginosa serotype O11 accounted for 34 (76%) of 42 of the strains serotyped. The total increase in incidence of P. aeruginosa endocarditis that we observed can be attributed to disease caused by serotype O11. We serotyped 152 strains of P. aeruginosa obtained from hospital inpatients without endocarditis. Serotype O11 was the most frequently isolated type, accounting for 27% of the total. Incidence of serotype O11 in drug addicts with endocarditis is significantly higher than the incidence in patients with nonendocarditis infections (chi 2 = 32.89; P less than .001). There was a high degree of correlation between pentazocine and tripelennamine ("T's and Blues") abuse and endocarditis caused by P. aeruginosa (chi 2 = 36.71; P less than .001).     

Epidemic diarrhea at Crater Lake from enterotoxigenic Escherichia coli. A large waterborne outbreak.

In June and July 1975, Gastrointestinal illness occurred in more than 200 staff members and 2000 visitors to an American national park. In was characterized by prolonged diarrhea, cramps, nausea, and vomiting, lasted a median duration of 8 days, and was significantly associated with consumption of park water (P less than 0.001), which had been contaminated by raw sewage. Enterotoxigenic Escherichia coli serotype 06:K15:H16 was isolated from 20 of 49 ill park residents and from the park's water supply, but not from 71 residents who had never been ill or had been well for at least 4 days. No other bacterial, viral, or parasitic pathogens were isolated from ill or well persons. This outbreak is the first waterborne epidemic of diarrheal illness shown to be due to enterotoxigenic. E. coli, and this study documents one mode of transmission of this pathogen. This investigation also suggests the relative insensitivity of current methods for identifying persons infected with this organism, either by the culturing of randomly selected isolates or by measuring serologic responses.     

Association of systemic immune complexes, complement activation, and antibodies to Pseudomonas aeruginosa lipopolysaccharide and exotoxin A with mortality in cystic fibrosis

The relevance of circulating immune complexes, plasma complement activation, and serum antibodies against discrete antigens of Pseudomonas aeruginosa, to the clinical course in patients with cystic fibrosis (CF) is unknown. We related these factors to outcome in 49 patients with CF colonized by P. aeruginosa, comparing 14 who died of lung disease with 35 survivors of similar age and duration of colonization, as well as 9 uncolonized patients with CF, 24 patients with other bronchorrheic lung disease, and 10 healthy control subjects. The patients with CF colonized by P. aeruginosa who died had a higher incidence of immune complexes than did survivors (71 versus 40%, p less than 0.05). Moreover, C4 activation was highly associated with immune complexes and mortality (p less than 0.001 for each). Those who died also had much higher levels of IgG antibodies to P. aeruginosa lipopolysaccharide (LPS) and exotoxin A than did survivors colonized by P. aeruginosa (p less than 0.005 and p = 0.01, respectively), whereas both groups had similar levels of P. aeruginosa sonicate, elastase, alkaline protease, and endotoxin core antibodies. We conclude that increasing levels of serum IgG antibodies to P. aeruginosa LPS and exotoxin A and the presence of systemic immune complexes and complement activation are associated with poor prognosis in CF, and may provide useful noninvasive markers for studying the possible immunopathogenesis of CF lung disease.     

Campylobacter enteritis from untreated water in the Rocky Mountains

During the summers of 1980 and 1981 Campylobacter jejuni was isolated from 23% and Giardia lamblia was isolated from 8% of persons with diarrheal disease acquired in the area of Grand Teton National Park, Wyoming. Campylobacter enteritis occurred most frequently in young adults who had been hiking in wilderness areas and was significantly associated with drinking untreated surface water in the week before illness (p less than 0.02 in 1980; p less than 0.005 in 1981). Penner serotype 4 was the commonest serotype isolated from humans and the only serotype isolated from an implicated mountain stream. These studies show that backcountry surface water can be an important source of C. jejuni and that infection with Campylobacter, as well as G. lamblia, should be considered as a cause of diarrhea in those who have recently returned from wilderness areas.     

Characterization of the human immune response to a polysaccharide vaccine from Pseudomonas aeruginosa

Sera from humans vaccinated with a high-molecular-weight polysaccharide vaccine to Pseudomonas aeruginosa immunotype 1 (IT-1) were analyzed for duration of the immune response, specificity for the IT-1 determinant, and by assessing the immunoglobulin classes elicited. The ability of purified IgG, IgM, and IgA to interact with peripheral blood leukocytes, as well as purified polymorphonuclear neutrophils or mononuclear cells, was also examined in an opsonophagocytosis assay. Levels of antibody to IT-1 remained significantly (P less than 0.001) elevated 21 months after immunization. Responses were generally specific to the IT-1 serotype determinant. Some vaccinees also responded to immunotype 2 and immunotype 5 determinants. IgG, IgM, and IgA serum antibodies were all elicited by vaccination. IgG and IgA were effective opsonins for P aeruginosa. IgM-mediated opsonophagocytosis required complement. Serum IgA was highly effective in conjunction with mononuclear cells in opsonophagocytosis of P aeruginosa, suggesting that these immune components may be capable of protecting neutropenic hosts.     

Characterization of a human monoclonal antibody to lipopolysaccharides of Pseudomonas aeruginosa serotype 5: a possible candidate as an immunotherapeutic agent for infections with P. aeruginosa

A human monoclonal antibody, P3D9 (IgG2, lambda type), that bound to Pseudomonas aeruginosa Homma serotype 5 cells with high specificity was produced by cell fusion between a human tonsillar lymphocyte and a mouse plasmacytoma cell, P3-X63-Ag8-U1 (P3U1). The yield of P3D9 secreted into the culture supernatant from the mouse-human hybridoma was 2-10 micrograms/ml, and this hybridoma cell line has been stably producing this antibody for six months. Antibody P3D9 alone did not cause agglutination of serotype 5 cells, but the cells were agglutinated after addition of goat antibody to human IgG. Antibody P3D9 was proven to have protective activity against infection with P. aeruginosa, and the 50% protective dose estimated for experimental peritoneal infection with P. aeruginosa was 2.4 micrograms per mouse.     

Septicemia caused by Pseudomonas aeruginosa serotype O 16 in a hemato-oncology department. Review of 17 cases

Seventeen cases of Pseudomonas aeruginosa serotype O 16 septicaemia in patients with immune deficiencies are reported. All patients had a poor prognosis from the onset because of the advanced stage of their illness, the particular clinical form of their disease or because of the confirmed inefficacy of their anti-leukaemic chemotherapy. The neutrophil leukocyte count was less than 0.5 X 10(9)/l in all cases and 13 patients had also received wide-spectrum antibiotic therapy for at least 15 days. The septicaemia was accompanied by pelvic sepsis in 6 cases. The prognosis was very poor and 12 patients died rapidly in a state of shock. P. aeruginosa was an infrequent cause of infection during the 31 months period of observation but the O 16 serotype was the commonest in our department. The source of contamination seemed to be a chronic carrier state. P. aeruginosa is resistant to most of the antibiotics which would be expected to be effective.     

Selective survival in pentazocine and tripelennamine of Pseudomonas aeruginosa serotype O11 from drug addicts

The growth of Pseudomonas aeruginosa, particularly serotype O11, in pentazocine and tripelennamine ("T's and Blues") was evaluated as a possible explanation for the association of deep-seated infection with this organism and abuse of these drugs. The mean reduction of growth caused by the drugs was 1,000-fold greater for 49 Pseudomonas strains from normal subjects than for 32 strains from drug addicts (4.2 vs. 1.3 logs of reduction at 2 hr, P less than .0005). A common phenotypic subset of the serotype O11 strains from drug addicts was especially resistant to the inhibitory effects. Twelve strains of Staphylococcus aureus (a frequent cause of infection in heroin, but not in pentazocine and tripelennamine, addicts) were completely inhibited by the drug combination. Dose-response curves (derived from the results of using the tablets as well as pure powders) showed that tripelennamine was responsible for the inhibitory activity, which was partially antagonized by pentazocine. We conclude that an ability of some P. aeruginosa serotype O11 strains, but not S. aureus, to survive in pentazocine and tripelennamine may explain in part a shift from S. aureus to P. aeruginosa as common pathogens of drug addicts in areas where abuse of this combination of drugs has increased.     

Prevalence of coronary risk factors in elderly blacks and whites.

Coronary risk factors were determined in a prospective study of 1,414 elderly persons (999 women and 415 men), mean age 82 +/- 8 years. Of 1,414 persons, 215 (15%) were black and 1,140 (81%) were white. The prevalences of cigarette smoking, hypercholesterolemia, low serum high-density lipoprotein cholesterol, and increased serum total cholesterol/high-density lipoprotein cholesterol ratio were not significantly different in elderly blacks and whites. Elderly blacks had a higher prevalence of hypertension (50% versus 36%, P less than 0.001), diabetes mellitus (27% versus 19%, P less than 0.01), and obesity (11% versus 5%, P less than 0.005) and a lower prevalence of hypertriglyceridemia (9% versus 15%, P less than 0.05) than elderly whites. In elderly persons with hypertension, electrocardiographic left ventricular hypertrophy occurred in 19% of blacks and 14% of whites (P not significant), echocardiographic left ventricular hypertrophy occurred in 72% of blacks and 56% of whites (P less than 0.01), and concentric left ventricular hypertrophy occurred in 60% of blacks and 39% of whites (P less than 0.001).     

Investigations on the etiology of sepsis by using experimental mouse model with leukocytopenia. 1. Influence of antibiotics

Investigation on the etiology of septicemia occurring among the immunocompromised patients was performed by using experimental model of the mouse with leukocytopenia. The ddY conventional mice of 4 weeks of age were inoculated with cyclophosphamide (CPM) intraperitoneally 3 to 5 times every other day with a dose of 3 mg/mouse once to make an agranulocytic status. Then, intraperitoneal administrations of various antibiotic regimens consisting of ampicillin (ABPC) alone, ABPC + ceftazidime (CAZ), ABPC + CAZ + cloxacillin (MCIPC), ABPC + CAZ + MCIPC + minocycline (MINO) and saline as a control to these immunosuppressed mice were begun once every day for 10 days after the second inoculation of CPM. The mortality rate of the mice given saline as a control was very high with a frequency of 43.3% and there were significant differences between the saline group and another antibiotic groups other than ABPC (p less than 0.01). On the other hand, the mortality rate of the group given APBC showed the highest rate of 70% and it was significantly higher than that of the saline control group (p less than 0.05). The main cause of most of the dead mice was septicemia due to P. aeruginosa and which were isolated from the feces of all these mice and serotype of the strains isolated from the heart blood and feces in the same host corresponded to each other. Moreover, intestinal bacterial flora in mice treated by saline and ABPC which highly showed Pseudomonas sepsis, was occupied dominantly by P. aeruginosa, although P. aeruginosa was not detectable from the experimental environments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Outbreak of severe Pseudomonas aeruginosa infections caused by a contaminated drain in a whirlpool bathtub.

During a 14-month period, 7 patients with hematological malignancies acquired serious infections caused by a single strain of multiply resistant Pseudomonas aeruginosa. A case-control study, culture surveys, and pulsed-field gel electrophoresis implicated a whirlpool bathtub on the unit as the reservoir. All case patients and 32% of control patients used this bathtub (P=.003). The epidemic strain was found only in cultures of samples taken from the bathtub. The drain of the whirlpool bathtub, which was contaminated with the epidemic strain, closed approximately 2.54 cm below the drain's strainer. Water from the faucet, which was not contaminated, became contaminated with P. aeruginosa from the drain when the tub was filled. The design of the drain allowed the epidemic strain to be transmitted to immunocompromised patients who used the whirlpool bathtub. Such tubs are used in many hospitals, and they may be an unrecognized source of nosocomial infections. This potential source of infection could be eliminated by using whirlpool bathtubs with drains that seal at the top.     

Simple electrocardiographic markers for the prediction of paroxysmal atrial fibrillation in hyperthyroidism

BACKGROUND: Hyperthyroidism is a major cause of paroxysmal atrial fibrillation (AF). The purpose of this study was to evaluate the predictors of AF in the patients with clinical and subclinical hyperthyroidism. METHODS AND RESULTS: The study population consisted of four groups: group I (57 euthyroid healthy persons), group II (33 patients with subclinical hyperthyroidism), group III (69 patients with overt hyperthyroidism) and group IV (31 patients with overt hyperthyroidism and documented paroxysmal AF). The maximum P wave duration (P maximum) in group IV (114 +/- 8 ms) was significantly higher than group I (102 +/- 7 ms, p < 0.001), group II (106 +/- 7 ms, p < 0.001) and group III (108 +/- 9 ms, p0.005). The P wave dispersion (PWD) was measured as 46 +/- 9 ms in group IV and this was significantly higher than group I (29 +/- 8 ms, p < 0.001), group II (36 +/- 9 ms, p < 0.001) and grup III (38 +/- 8 ms, p = 0.001). The P maximum and PWD were higher in the patients with subclinical hyperthyroidism compared to healthy individuals. Univariate regression analysis revealed that age, P maximum and PWD, multivariate analysis showed that P maximum and PWD were significant predictors of paroxysmal AF. A PWD value of 37.5 ms separated group IV from others with a sensitivity of 90%, specificity of 85%, and positive predictive accuracy of 77%. CONCLUSION: Simply measuring P maximum and PWD values, we could identify the patients with high risk for the development of AF and these simple ECG parameters may help in clinical judgement to determine the requirement for treatment in the patients with subclinical hyperthyroidism.     

Pharyngoconjunctival fever caused by adenovirus type 4: report of a swimming pool-related outbreak with recovery of virus from pool water.

During the summer of 1977, an outbreak of pharyngoconjunctival fever (PCF) occurred at a private recreational facility in Georgia. A total of 72 cases of PCF was identified. Adenovirus type 4 (AV-4) was recovered from conjunctival or pharyngeal swab specimens from 20 of 26 persons in the group of cases tested. AV-4 was also recovered, for the first time reported in the literature, from two concentrated samples of water obtained from the swimming pool at the facility on different dates. All persons affected had had direct or indirect contact with the pool. A linear relation between the amount of time spent in the water and the attack rate was demonstrated (r = 0.929, P less than 0.01). Investigation showed that inadequate amounts of chlorine had been added to the pool water. Frequently, levels of free chlorine were below the recommended level of 0.4 mg/liter. Breakpoint chlorination and closing of the pool for the summer stopped the spread of PCF.     

Ability of high-intensity ultrasound to ablate human atherosclerotic plaques and minimize debris size

To investigate whether high-intensity ultrasound can destroy atherosclerotic plaques while sparing the normal arterial wall, 279 normal human aortic sites and 119 fibrous and 193 calcified plaques, obtained from 24 necropsies, were insonified in a water tank, at 20 kHz and at 5 different power intensities, ranging from 68 W/cm2 (P1) to 150 W/cm2 (P5). These intensities were associated with a total excursion of the ultrasound irradiation apparatus tip from 90 to 268 microns, respectively. Time to perforate normal aortic sites and fibrous and calcified plaques was recorded at each intensity. There was no difference in perforation time between normal aortic sites and fibrous and calcified plaques when high-power levels (P2 to P5) were used. However, at the lowest power (P1), perforation time for the normal aortic wall was significantly longer than for fibrous and calcified plaques: 30 +/- 18 seconds (166 observations), 14 +/- 7 seconds (p less than 0.001) (78 observations) and 12 +/- 8 seconds (p less than 0.001) (115 observations), respectively. When perforation times for normal vessel wall versus fibrous plaque and normal vessel wall versus calcified plaque from the same necropsy specimen were compared in a pairwise manner, the results were: 29 +/- 13 vs 16 +/- 7 (p less than 0.001) (48 paired observations) and 26 +/- 9 vs 10 +/- 5 seconds (p less than 0.001) (55 paired observations), respectively. Regardless of whether paired or unpaired comparison was applied, no significant difference was found in perforation time between fibrous and calcified plaques. The debris did not differ in size as measured separately for normal sites and fibrous and calcified plaques by a computer-interfaced Channelizer and Coulter Counter system.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fatal Pseudomonas aeruginosa pneumonia in a previously healthy woman was most likely associated with a contaminated hot tub

Community-acquired pneumonia due to Pseudomonas aeruginosa in previously healthy individuals is a rare disease that is associated with high fatality. On 14 February 2010 a previously healthy 49-year-old woman presented to an emergency room with signs and symptoms of pneumonia, 2 days after returning from a spa holiday in a wellness hotel. Blood cultures and respiratory specimens grew P. aeruginosa. Despite adequate antimicrobial therapy, the patient died of septic multiorgan failure on day nine of hospitalization. On February 26, nine water samples were taken from the hotel facilities used by the patient: In the hot tub sample 37,000 colony-forming units of P. aeruginosa/100 ml were detected. Two of five individual colonies from the primary plate used for this hot tub water sample were found to be genetically closely related to the patient's isolates. Results from PFGE, AFLP and MLST analysis allowed the two lung isolates gained at autopsy and the whirlpool bathtub isolates to be allocated into one cluster. The patient most likely acquired P. aeruginosa from the contaminated water in the hotel's hot tub. The detection of P. aeruginosa in high numbers in a hot tub indicates massive biofilm formation in the bath circulation and severe deficiencies in hygienic maintenance. The increasing popularity of hot tubs in hotels and private homes demands increased awareness about potential health risks associated with deficient hygienic maintenance.     

A comparative study of enterotoxigenic Escherichia coli, Shigella, Aeromonas, and Vibrio as etiologies of diarrhea in northeastern Thailand

The incidence of enterotoxigenic Escherichia coli (ETEC), Shigella, Aeromonas, and Vibrio was determined in patients with diarrhea seen at a hospital in northeastern Thailand, and compared with the incidence of these bacteria in household contacts and their neighbors. ETEC was identified in 17%, Shigella in 9%, Aeromonas in 9%, V. parahaemolyticus in 5%, and non-01 V. cholerae in 2% of 299 patients with diarrhea. These five species of bacteria were isolated more often from patients with diarrhea than persons without diarrhea (P less than 0.001). ETEC was found more often in household contacts (22/141) and neighbors (18/147) of index cases than in persons living in homes not associated with ETEC infections (32/1,318; P less than 0.001). While Shigella was isolated less often in family contacts (3/76) and neighbors (4/93) of patients with shigellosis, this enteric pathogen was also isolated more often from contacts than persons not associated with Shigella infection (13/1,437; P less than 0.001). Both Aeromonas and non-01 V. cholerae can also be enteric pathogens; further efforts should be made to define the enteropathogenicity of these bacteria.     

Protection against infection with Pseudomonas aeruginosa by passive transfer of monoclonal antibodies to lipopolysaccharides and outer membrane proteins

Experimental infection with Pseudomonas aeruginosa was treated with eight different monoclonal antibodies (MCAs) produced by hybridoma cells obtained through cell fusion of mouse plasmacytoma cells and spleen cells from mice immunized with a virulent strain of P. aeruginosa (Homma serotype 7). Five MCAs bound to lipopolysaccharides (LPSs) specific to serotype 7 or serotypes 2, 7, and 13, whereas the other three MCAs bound with broad specificities to outer membrane protein (OMP) fractions. The MCAs to LPS were highly protective against infection, with 50% protective doses of 0.05-2.5 micrograms of immunoglobulin per mouse. In contrast, the MCAs to OMP were much less protective, with a 50% protective dose range of 10 to greater than 100 micrograms of immunoglobulin per mouse. Most of the MCAs to LPS agglutinated P. aeruginosa cells, but all the MCAs to OMP produced so far have not, although all the MCAs bound well to the cells. Agglutinating MCAs provided better protection than did nonagglutinating MCAs.     

Incidence and determinants of Pseudomonas aeruginosa infection among persons with HIV: association with hospital exposure

BACKGROUND: Little information exists on risk factors for Pseudomonas aeruginosa infection in persons with HIV. We assessed the incidence and factors associated with P aeruginosa among persons with HIV enrolled in a large observational cohort study in Los Angeles. METHODS: Data were analyzed from 4825 persons aged > or =13 years with HIV infection enrolled from 4 outpatient facilities from 1990 to 1998. The association between P aeruginosa infection and demographic, risk behavior, and clinical factors was assessed. RESULTS: P aeruginosa was diagnosed in 72 (1.5%) patients representing a crude incidence rate of 0.74 per 100 person-years. The most frequent site of infection was pulmonary (47%). In multivariate analysis, prior hospitalization (adjusted rate ratio = 7.9, 95% CI, 3.8-16.2), and both dapsone (adjusted rate ratio = 4.0, 95% CI, 2.2-7.4) and trimethoprim-sulfamethoxazole (adjusted rate ratio = 2.5, 95% CI, 1.2-5.3) use were independently associated with higher rates of infection. Increasing days of inpatient stay (P <.01) and decreasing CD4(+) counts (P <.01) were strongly associated with P aeruginosa. Azithromycin use decreased the risk of infection by nearly 70%. CONCLUSION: Although the overall observed incidence of P aeruginosa was low, hospital exposure, declining CD4(+) levels, and the use of dapsone or trimethoprim-sulfamethoxazole increased the risk of P aeruginosa disease, and azithromycin use was protective in this population. These findings may assist in the early recognition and diagnosis of persons likely to be at increased risk of P aeruginosa infection.