Epidemiological typing of uropathogenic Pseudomonas aeruginosa strains from hospitalized patients

Urinary tract infections and catheter-associated urinary tract infections caused by Pseudomonas aeruginosa

SUMMARYUrinary tract infection (UTI) is one of the most common infections in otherwise healthy individuals. UTI is also common in healthcare settings where patients often require urinary catheters to alleviate urinary retention. The placement of a urinary catheter often leads to catheter-associated urinary tract infection (CAUTI) caused by a broad range of opportunistic pathogens, commonly referred to as ESKAPE (Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, and Enterobacter) pathogens. Our understanding of CAUTI is complicated by the differences in pathogens, in initial microbial load, changes that occur due to the duration of catheterization, and the relationship between infection (colonization) and disease symptoms. To advance our understanding of CAUTI, we reviewed UTI and CAUTI caused by Pseudomonas aeruginosa which is unique in that it is not commonly found associated with human microbiomes. For this reason, the ability of P. aeruginosa to cause UTI and CAUTI requires the introduction of the bacteria to the bladder from catheterization. Once in the host, the virulence factors used by P. aeruginosa in these infections remain an area of ongoing research. In this review, we will discuss studies that focus on P. aeruginosa UTI and CAUTI to better understand the infection dynamics and outcome in clinical settings, virulence factors associated with P. aeruginosa isolated from the urinary tract, and animal studies to test which bacterial factors are required for this infection. Understanding how P. aeruginosa can cause UTI and CAUTI can provide an understanding of how these infections initiate and progress and may provide possible strategies to limit these infections.

Bacteriophages of Pseudomonas aeruginosa: long-term prospects for use in phage therapy

Bacteria Pseudomonas aeruginosa, being opportunistic pathogens, are the major cause of nosocomial infections and, in some cases, the primary cause of death. They are virtually untreatable with currently known antibiotics. Phage therapy is considered as one of the possible approaches to the treatment of P. aeruginosa infections. Difficulties in the implementation of phage therapy in medical practice are related, for example, to the insufficient number and diversity of virulent phages that are active against P. aeruginosa. Results of interaction of therapeutic phages with bacteria in different conditions and environments are studied insufficiently. A little is known about possible interactions of therapeutic phages with resident prophages and plasmids in clinical strains in the foci of infections. This chapter highlights the different approaches to solving these problems and possible ways to expand the diversity of therapeutic P. aeruginosa phages and organizational arrangements (as banks of phages) to ensure long-term use of phages in the treatment of P. aeruginosa infections.

Emergence of multidrug resistance in ubiquitous and dominant Pseudomonas aeruginosa serogroup O:11. The Greek Pseudomonas Aeruginosa Study Group

The serotypes of 88 nonreplicate nosocomial Pseudomonas aeruginosa isolates from 11 Greek hospitals were studied in relation to their antibiotic susceptibilities. Rates of resistance to beta-lactams, aminoglycosides, and quinolones ranged from 31 to 65%, except for those to ceftazidime (15%) and imipenem (21%). Four serotypes were dominant: O:12 (25% of isolates), O:1 (17%), O:11 (16%), and O:6 (10%). Multidrug resistance rates in the major serogroups O:12 (91%) and O:11 (79%) were higher than those in serogroups O:1 (40%) and O:6 (43%). Further typing with respect to pulsed-field gel electrophoresis patterns following XbaI digestion of genomic DNA discriminated the isolates into 74 types. Pulsed-field gel electrophoresis revealed that the ubiquitous O:12 group was genetically homogeneous, since 95% of strains belonged to two clusters of genotypic similarity, while the O:11 strains, present in 8 of the 11 hospitals, were distributed among five such clusters. Therefore, apart from the already reported O:12 multidrug-resistant European clone, an O:11 population, characterized by a serotype known to be dominant in the environment and the hospital in several parts of the world, but previously not associated with multidrug resistance to antibiotics, has progressed to a multidrug-resistant state.

EVALUATION OF HOSPITAL ACQUIRED PSEUDOMONAS INFECTION IN PARAPLEGIC AND ORTHOPAEDIC CASES

One hundred isolates of Pseudomonas aeruginosa from patients of the spinal cord injury and orthopaedic centre were evaluated on the basis of 2 laboratory assays; antibiotic sensitivity and pyocin typing. Antibiotic drug resistance was found in 54 per cent of the isolates. The urinary tract, pressure sores and wound swabs were the most common clinical specimens. Spinal cord injury patients showed a high rate of nosocomial colonisation. Ceftazidime, amikacin, norflox and ciprofloxacin were the most active antimicrobial agents. Gentamicin, carbenicillin and tobramycin showed high resistance. Pyocin typing with 22 strains did yield information to establish a clinico - epidemiological relationship.

In vitro activity of commercially manufactured disinfectants against Pseudomonas aeruginosa

The in vitro activity of 17 commercially manufactured disinfectants routinely used in a large teaching hospital was tested against 128 strains of Pseudomonas aeruginosa isolated from hospitalized patients and the hospital environment. Except for quaternary ammonium salts, all the disinfectants at dilutions higher or equalling those recommended by the manufacturer were adequate to suppress P. aeruginosa. Chlorhexidine-, povidone-iodine- and glutaraldehyde-based disinfectants at dilutions 4 to 8-fold lower than the normal use dilution had a marked bactericidal effect ( > 3 log10 reduction of viable cells) within a short time (10 to 120 min). Similar formulations produced by different manufacturers exhibited comparable activity against P. aeruginosa.

Characteristics of Pseudomonas aeruginosa strains isolated from urinary tract infections

Thirty-three uropathogenic strains of Pseudomonas aeruginosa were investigated for hemolytic activity in both bacterial broth culture filtrates and isolate lyzates, resistance to bactericidal activity of fresh human serum, resistance to six antibiotics and plasmid DNA profile. Twenty-four of the 33 (73%) bacterial filtrates showed lysis of rabbit erythrocytes, as did the three after guinea-pig erythrocyte treatment. Twelve of 33 isolate lysates showed in parallel lysis of both types of erythrocytes used. Serum resistance was found in 17 (52%) isolates, intermediate resistance in 15 (45 %) isolates and only one isolate showed serum sensitivity. Resistance to antibiotics was detected as follows (in %): tetracycline 94, kanamycin 79, chloramphenicol 76, septrin 73, ampicillin 64, streptomycin 45, gentamicin 18. None of the isolates investigated showed resistance to colistine. With the exception of one isolate, plasmid DNA was detected in all P. aeruginosa strains.

Continuing the search for bacterial urovirulence factors

Bacteria that commonly cause infections of the normal urinary tract (eg Escherichia coli, Proteus mirabilis and Staphylococcus saprophyticus) do so because they possess specific urovirulence factors. Adhesions of various types (often fimbriae) seem to be the most important of these. In E. coli several other factors have been recognized, and sub-sets of defined uropathogenic clones exist. On the other hand, urovirulence determinants are less easy to distinguish in species such as S. epidermidis and Klebsiella pneumoniae, that rarely cause such infections, or are pathogenic only in the presence of some abnormality or deficiency in host defences.

Genome fingerprinting by pulsed-field gel electrophoresis and ribotyping to differentiate Pseudomonas aeruginosa serotype O11 strains

The performance of ribotyping and pulsed-field gel electrophoresis was compared in the differentiation of a collection of 44 Pseudomonas aeruginosa serotype O11 strains isolated in seven hospitals in Singapore. Digestion of genomic DNA by EcoRI and SacI followed by Southern hybridization with the Pseudomonas aeruginosa 16S and 23S rRNA gene revealed seven distinct ribotypes. Ribotyping using a combination of both enzymes revealed 11 ribotypes. In contrast, electrophoretic analysis differentiated 41 different strain types among the 44 clinical isolates using either SpeI or DraI. Pulsed-field gel electrophoresis demonstrated greater sensitivity than ribotyping in the differentiation of Pseudomonas aeruginosa strains of the same ribotype and could thus be used alone in epidemiological investigations of hospital outbreaks of Pseudomonas aeruginosa serotype O11 infection.

Virulence determinants in Pseudomonas aeruginosa strains from urinary tract infections

A total of 121 uropathogenic Pseudomonas aeruginosa strains were examined for production of several virulence-related factors. These strains were distributed in five predominant O-serotypes, i.e. O 4, O 12, O 11, O 6 and O 5, which accounted respectively for 23.9, 23.1, 12.3, 8.2 and 5.7% of isolates. Pyochelin and pyoverdin siderophores were produced by most of the isolates, defective variants occurring at very low frequency (2.4% for pyochelin and 7.4% for pyoverdin). Adherence to uroepithelial cells and production of cytotoxins was demonstrated in 52.8 and 67.7% of the strains, respectively, with higher frequencies for epidemiologically related strains belonging to serotypes O 4 and O 12. Titration of total proteases, elastase and phospholipase C revealed a high degree of heterogeneity among isolates. However, examination of individual O-serotypes by exoenzyme production showed that elevated levels of total proteases and elastase were characteristics of serotypes of minor numerical importance, i.e. O 1, O 10, O 11 and O 17, whilst low levels of elastase were produced by strains belonging to the predominant serotypes, namely O 4 and O 12. Moreover, epidemiologically related strains belonging to serotypes O 4 and O 12 appeared more homogeneous than the whole serogroup, when compared with other groups on the basis of exoenzyme levels.