Typing of Staphylococcus aureus by pulsed-field gel electrophoresis, zymotyping, capsular typing, and phage typing: resolution of clonal relationships

Sixty-nine Staphylococcus aureus isolates from two epidemiologically unrelated sources were typed by pulsed-field gel electrophoresis after SmaI digestion of chromosomal DNA (genome typing), and the results were compared with those obtained by other typing methods: phage typing with the international set of phages, capsular serotyping with monoclonal antibodies against capsular polysaccharides type 5 and 8, and zymotyping by polyacrylamide agarose electrophoresis for esterase polymorphism. A good correlation of S. aureus types was found by these four typing methods. Differentiation increased in the order capsular typing < zymotyping < phage typing < genome typing, yielding 2, 10, 20, and 26 different S. aureus types, respectively. Five of the 26 genome types were further divided into several subtypes revealing clonal relationships. When 36 French S. aureus isolates were compared with 33 German S. aureus isolates, 3 strains representing clonal populations were identical in both groups. S. aureus isolates from patients with cystic fibrosis were also typed at the beginning and the end of a 4-week summer camp for these patients. The results suggested a possible strain transmission during the summer camp. We conclude that genome typing by pulsed-field gel electrophoresis is a powerful tool not only for strain identification but also for the resolution of the clonal relationships of S. aureus strains.

False aneurysm infected by Aspergillus fumigatus: an unusual complication of aortofemoral bypass graft

Two cases of Aspergillus fumigatus infection of aortobifemoral prosthetic grafts are reported. Both patients were treated successfully by excision of the infected prosthetic material, axillofemoral extra-anatomic bypass, and prolonged medical treatment. The patients received amphotericin B, 5-flucytosine and itraconazole until negative aspergillus serology was obtained (at 9 and 18 months, respectively). Later, repeat disobliteration procedures for thrombosis of the axillofemoral bypass were required. No recurrent aspergillus infection was found.

Epidemiological markers for epidemic strain and carrier isolates in an outbreak of nosocomial oxacillin-resistant Staphylococcus aureus

An outbreak of nosocomial infections occurring in a postoperative intensive care unit was caused by a single strain of oxacillin-resistant Staphylococcus aureus. Six patients were infected, or colonized, by this strain, which was traced by using the following four epidemiological markers: antibiogram, bacteriophage type, capsular polysaccharide type, and esterase electrophoretic type. This strain was compared with S. aureus isolates obtained from the noses of 13 carriers from a group of 42 staff members. A good correlation in terms of phenotypic markers was found between the epidemic strain and a strain isolated from one carrier. Both exhibited the same pattern of multiple resistance as well as the same phage type, 77, capsular polysaccharide type, 5, and esterase electrophoretic type, 6. In contrast, an oxacillin-resistant strain, isolated from another carrier, differed from the epidemic strain by susceptibility to rifampin and by susceptibility to four additional bacteriophages. The other 11 strains isolated from carriers were susceptible to oxacillin and exhibited widely different phenotypes. These results confirm the interest of using several epidemiological markers to trace the spread of epidemic S. aureus strains and to delineate the carrier strains.

Correlation between esterase electrophoretic types and capsular polysaccharide types 5 and 8 among methicillin-susceptible and methicillin-resistant strains of Staphylococcus aureus

The relationship between capsular polysaccharide types 5 and 8 and esterase electrophoretic types (zymotypes) in 160 French clinical isolates of Staphylococcus aureus was studied. Methicillin-susceptible strains of capsular types 5 and 8 were represented by 11 zymotypes, indicating a high polymorphism. Methicillin-resistant strains were mainly distributed in only two distinct populations. The predominant population was represented by strains of zymotype 6 and capsular type 5, and the second population was represented by strains of zymotype 14 and capsular type 8.

Genetic heterogeneity in methicillin-resistant strains of Staphylococcus aureus revealed by esterase electrophoretic polymorphism

136 methicillin-resistant strains of Staphylococcus aureus recovered from hospitalized patients in 18 countries were characterized by electrophoretic mobilities of three types of esterases. These were defined by their ranges of activity toward five synthetic substrates and their resistance to di-isopropyl fluorophosphate. Fourteen zymotypes were distinguished. Two, designated as 6 and 14, were found in 53 and 50 strains, respectively. Genetic diversity coefficients were lower for strains from France and from other European countries (H = 0.47 and 0.53, respectively) than for strains from North America (H = 0.79). On the basis of electrophoretic polymorphism of esterases, our work provides evidence that methicillin-resistance is expressed in genetically different strains. Variations in esterase electrophoretic pattern within methicillin-resistant strains of S. aureus can make a significant contribution to the study of their epidemiology.

Isolation and properties of carboxylesterase P4 from Yersinia pseudotuberculosis

The carboxylesterase P4 produced by Yersinia pseudotuberculosis was purified 330-fold by gel permeation and DEAE-trisacryl chromatography with a final yield of 21%. The apparent molecular weight, as determined by fast-protein liquid chromatography, was 45 kDa. The hydrolytic activity of esterase P4 was higher with the 1-naphthyl esters than with the 2-naphthyl esters of acetic, propionic and butyric acids. The apparent Km values were identical for 1-naphthyl acetate and 1-naphthyl propionate (0.15 mM). The enzyme was unstable at pH values below 5, but retained 80% of its initial activity after 30 min at 65 degrees C. It was unaffected by EDTA, eserine, tosyl-L-lysine chloromethylketone, iodoacetamide or 4-hydroxymercuribenzoate, but was strongly inhibited by low concentrations of diisopropyl fluorophosphate, suggesting the presence of serine in its active site. The purified enzyme gave a single precipitin line on Ouchterlony double immunodiffusion with homologous antiserum. This antiserum cross-reacted with the esterase bands E3 and E5 of Y. enterocolitica biotype 1, whereas there was no cross-reaction with the esterase bands produced by Y. enterocolitica biotypes 2 to 5, Y. intermedia, Y. frederiksenii, Y. kristensenii or Y. aldovae. The carboxylesterase P4 produced by Y. pestis was physicochemically, biochemically and immunologically indistinguishable from Y. pseudotuberculosis carboxylesterase P4. The latter enzyme and carboxylesterase B of Escherichia coli showed some biochemical similarities, but were antigenically unrelated. Our data confirm the relevance of esterases to phylogenetic and taxonomic studies of Enterobacteria.

Effects of sepsis on diaphragmatic function in rats

The effects of a 3-day pneumococcal infection on diaphragmatic strength and endurance capacity were studied in an in vivo rat model. Thirty-four rats were divided into a control (C) (n = 17) or a septic (S) group (n = 17). Animals were inoculated subcutaneously with 10(11) Streptococcus pneumoniae (S), or sterile culture media (C). All rats were studied 3 days after inoculation. Diaphragmatic strength and endurance capacity were studied in 11 animals of each group. Diaphragmatic strength was assessed by measuring transdiaphragmatic pressure (Pdi) generated during electrical stimulation of the phrenic nerves at different frequencies (0.5, 10, 20, 30, 50, and 100 Hz). Endurance index was calculated as the ratio of Pdi generated after 30 s of phrenic nerve stimulation at 10 Hz divided by the initial force. Measurements of lung weights and lung histologic examinations were performed in the 6 remaining rats from each group. S animals were hyperthermic (39 to 40 degrees C rectal temperature). There was no evidence of pneumonia at histologic examination in Group S. No differences in wet weight of the lung and in the dry-to-wet weight ratio were noted in Group S as compared with Group C. However, S. pneumoniae was isolated from blood and lungs of S animals. Diaphragmatic weight was not different between S and C groups, whereas the weights of the extensor digitorium longus (EDL), tibialis anterior (TA), and soleus muscles were significantly reduced in Group S as compared to Group C.(ABSTRACT TRUNCATED AT 250 WORDS)

Septicemia caused by Propionibacterium granulosum in a compromised patient

A case of septicemia caused by Propionibacterium granulosum in a compromised patient is described. The patient responded to ampicillin therapy. Detailed antibiotic susceptibility data are presented.

Esterase electrophoretic polymorphism of methicillin-sensitive and methicillin-resistant strains of Staphylococcus aureus

Methicillin-sensitive and methicillin-resistant strains of Staphylococcus aureus from diverse geographic origins were analysed by polyacrylamide-agarose gel electrophoresis for esterase polymorphism. Three kinds of esterase bands, designated A, B and C, were defined by their ranges of activity toward five synthetic substrates and their resistance to di-isopropyl fluorophosphate. There were five allozymes of esterase A, four of esterase B and four of esterase C. Eighteen distinct combinations of allozymes (zymotypes) were distinguished amongst 105 strains analysed. Two major zymotypes were represented by 35 and 19 strains respectively, whereas other zymotypes were represented by one or, at most, seven strains. The coefficient of genetic diversity was lower for methicillin-resistant strains than for methicillin-sensitive strains. Most of the methicillin-resistant strains are represented by the two major zymotypes which differed from each other by the electrophoretic behaviour of the three esterases. These results indicate that, on the basis of esterase electrophoretic polymorphism, methicillin resistance is expressed in genetically different strains.

[pH and the bacteriology of gastroplasties after esogastric resection]

A study of pH of digestive fluid in 24 patients six days after esophagogastric resection (EGR) showed conservation of acidity (pH: 3 or less) in one-thirds of cases. Immediate postoperative course was invariable with respect to incidence of pneumopathy and fistulae. Fungal infection is almost a constant finding in digestive grafts together with microbial pullulation, with a linear relation to pH. Ecology of germs was that of digestive flora of patients with obstruction, selected by the antibiotic cover administered. Group D streptococci and Gram negative bacilli were usually resistant to cephalosporins. Regurgitation pneumopathy therefore requires modification of antibiotic therapy and possible antifungal treatment. When functional disturbance is provoked by EGR, as for example a reflux syndrome; only those patients (1/3) with a pH of 3 or less can obtain relief from treatment with antacids.

Prophylactic Timentin in patients undergoing thoracic or vascular surgery

Timentin (ticarcillin + clavulanic acid) and cefamandole were compared in 484 patients undergoing elective thoracic or vascular surgery. Two hundred and forty eight patients received three 3 g/200 mg injections of Timentin and 236 patients received three 0.75 g injections of cefamandole. The patients were evaluated at discharge. Among the 248 patients given Timentin, only six (2.4%) had a post-operative infection, while nine (3.8%) of the 236 patients given cefamandole had a post-operative infection. There was no statistically significant difference between the two treatment regimes. This comparative study shows that Timentin may be used for antibiotic prophylaxis of clean vascular or thoracic surgery.

[In vitro activity of the combination ticarcillin-clavulanic acid on bacterial isolates in surgery]

The in vitro activity of ticarcillin in combination with clavulanic acid was tested, by disc diffusion, against 1,380 clinical bacterial isolates and was compared with that of ticarcillin alone. 83.8% of the isolates were susceptible to ticarcillin + clavulanic acid, whereas 56.6% were susceptible to ticarcillin alone. Minimal inhibitory concentrations (MIC) of ticarcillin in the presence of 4 micrograms/ml of clavulanic acid were determined against 157 ticarcillin resistant (MIC greater than 128 micrograms/ml) but ticarcillin + clavulanic acid susceptible strains of Gram negative bacilli and against 20 strains of beta-lactamase producing Staphylococcus aureus. With the addition of clavulanic acid, MICs of ticarcillin were respectively less than or equal to 16 micrograms/ml and less than or equal to 64 micrograms/ml for 50 and 90% of the Gram negative bacilli. All the Staphylococcus aureus were inhibited by concentrations of ticarcillin less than or equal to 1 microgram/ml.

Vancomycin-resistant streptococci or Leuconostoc sp

Two strains of gram-positive cocci highly resistant to vancomycin (MICs of 512 and 1,024 micrograms/ml) were isolated from blood cultures in two compromised patients. These organisms were identified as Leuconostoc spp. Leuconostoc spp. are gram-positive cocci found in vegetables and dairy products; they had not been isolated previously from clinical specimens. The susceptibility of eight Leuconostoc spp. strains, including the two clinical isolates, to 23 antimicrobial agents was determined.

Antimicrobial susceptibility of Gemella haemolysans isolated from patients with subacute endocarditis

Gemella haemolysans, a member of the family Streptococcacae, was isolated from patients with subacute endocarditis. The minimal inhibitory concentrations of 21 antimicrobial agents for five strains of the organism were determined. All strains were highly sensitive to penicillin G and ampicillin. Cefotaxime was the most active cephalosporin tested. All strains were sensitive to vancomycin, chloramphenicol and rifampin. Four strains were sensitive to tetracycline and erythromycin. All strains demonstrated a low level of resistance to aminoglycosides and were highly resistant to sulfonamides and trimethoprim. Killing curves and checker-board titration demonstrated synergism between penicillin G and streptomycin or gentamicin, and also between vancomycin and streptomycin or gentamicin. The results suggest that penicillin G combined with an aminoglycoside can be recommended for the treatment of subacute endocarditis caused by Gemella haemolysans.