Epidemiological analysis of Pseudomonas aeruginosa strains isolated from a selected patient population in Brno, Czech Republic.

In the 1996/97 period, 1,413 Pseudomonas aeruginosa (PA) strains were isolated from 843 patients of the Brno teaching hospitals of St. Anne and Bohunice together with small groups from other hospitals. In the same period, 203 PA strains, used as controls, were isolated from 187 patients treated outside hospitals. Statistical evaluation was based on 1,023 hospital isolates and 189 control strains. A total of 16 isolates were recovered from the hospital environments and two from therapeutic swimming pools. The epidemiological analysis of these PA strains was based on pyocin typing, serological typing and phage typing. The most frequently occurring pyocin types amongst our strains fell into 8 pyocin-type groups. The prevailing groups differed significantly between the hospital patient and control groups. Similarly, serological typing identified differences in the predominant serotypes between hospital and control patients. The phage typing method revealed that the control PA strains were significantly more sensitive to 21 polyvalent bacteriophages used than the hospital isolates. In relation to pyocin and serological typing, strains isolated from the hospital environment showed characteristics similar to those of the PA strains isolated from hospital patients. Our results indicate that the majority of strain isolated from hospitalised patients had their origin from human or inanimate contacts in the hospitals.

Pseudomonas aeruginosa phage lysate as an immunobiological agent. 1. Selection of Pseudomonas aeruginosa clinical strains for phage lysate preparation.

A total of 2087 Pseudomonas aeruginosa isolates collected during the period 1994-1997 were used as starting material. Out of 1704 in-patient isolates, 299 strains were selected for the preparation of phage lysates but only five strains provided stable lysates, i.e., maintained the ability to be repeatedly and completely lysed by the appropriate phage in the course of several years. A set of 193 out-patients (189) and water sources (4) isolates failed to yield strains suitable for phage lysate preparation; 190 strains isolated abroad from patients with cystic fibrosis or respiratory infections included three isolates which, despite having a high degree of mucus production, were suitable for lysate preparation. The antigenic pattern of the phage lysates was ascertained by SDS-polyacrylamide gel electrophoresis.

A new bacteriophage typing scheme for Proteus mirabilis and Proteus vulgaris strains. 3. Analysis of lytic properties.

The lytic properties of 21 bacteriophages constituting a new typing set for Proteus were examined in 507 Proteus mirabilis and 29 P. vulgaris strains isolated from patients and healthy subjects. Comparison of their morphological, serological, genetic and lytic properties showed that, in the Myoviridae and Podoviridae families, some phages were so closely related that the presence of all of them in the set was redundant. Analysis of the lytic properties revealed that some of the bacteriophages were not active enough to facilitate the differentiation of Proteus strains. The size of the final typing set was reduced from 21 to 12 phages but it was suggested that, in order to improve the differentiation capacity of the set, new phages should be included.

Nosocomial infections caused by selected gram-negative bacteria at the Anaesthesiology and Intensive Care Unit of the Teaching Hospital in Brno.

In the course of 13 months we monitored the occurrence of strains of P. mirabilis, P. vulgaris, Kl. pneumoniae, including its indole-positive variant and S. marcescens in patients of the Anaesthesiology and Intensive Care Unit (AICU) of the Teaching Hospital (TH) in Brno. Out of 436 patients hospitalized at that time, 95 (21.8%) were colonized or infected by one or all of the bacterial species studied. Out of those 95 patients, 48 (50.5%) came to the AICU already colonized or infected by one of the studied agents mostly from other wards of the TH or from other hospitals. At the AICU, 32 of them were reinfected or superinfected by one, two or all of the bacterial species studied. Of the 436 hospitalized patients, 79 (18.1%) were newly infected, reinfected or superinfected. By serotyping, proticine production and proticine sensitivity (P-S) typing and phage typing we demonstrated the endemization of some P-S types and phage types of the bacterial species studied and their spreading among the contemporaneously hospitalized patients. The endemic strains of P. mirabilis included P-S types P5/S6, S7, S9 and P5/S6, S7; P0/S9; P1/S2, S11 and P1/S11. The two biotypes of Klebsiella, i.e. K. pneumoniae and K. oxytoca, were identically sensitive to some of the phages 1, 2, 3, 8 and 106, particularly to phages 2 and 3, or 2, 3 and 106. The isolated strains of Serratia were absolutely resistant to the 26 bacteriophages used.

A new phage typing scheme for Proteus mirabilis and Proteus vulgaris strains. 1. Morphological analysis.

A new bacteriophage typing set, composed of 22 phages, was established as a tool for differentiation of Proteus strains. All the phages were tailed and included 4 morphological types (A1, A2, B1 and C1). They were classified into the families Myoviridae, Siphoviridae and Podoviridae. From the set, 19 phages had double-stranded DNA and 3 were single-stranded DNA phages.