Biotyping, ribotyping and esterase electrophoresis as epidemiological tools for Acinetobacter baumannii.

An epidemiological survey was carried out over a one-week period to assess the spread of Acinetobacter baumannii in a medical intensive care unit. Fifty strains were isolated from patients colonized or infected by the organism and from a hospital environment. These strains belonged to biotypes 9 or 18. The rRNA gene restriction patterns (using EcoRI and PvuII as restriction endonucleases) and the esterase electrophoretic profiles were determined on 31 strains, using as comparison strain isolates from another intensive care unit of our hospital and from two other French hospitals. Four EcoRI ribotypes, four PvuII ribotypes and six esterase profiles were identified. All biotype 9 strains isolated in our hospital presented the same ribotype after EcoRI digestion, the same ribotype after PvuII digestion and the same zymotype. The same observation was made on most of the biotype 18 strains. Biotyping is an appropriate method for screening of strains, and ribotyping and esterase electrophoresis could be used as additional methods to delineate outbreaks of nosocomial infections caused by A. baumannii.

Esterase electrophoresis compared with biotyping for epidemiological typing of Acinetobacter baumannii strains.

Forty-nine Acinetobacter baumannii strains belonging to three biotypes and isolated from four hospitals were differentiated by electrophoretic typing of their esterases. Six main kinds of esterases were distinguished by their spectra of hydrolytic activity toward seven synthetic substrates. The electrophoretic variations of these enzymes were used to define ten zymotypes among the three biotypes. Esterase electrophoresis appeared to be more sensitive than biotyping, and could represent an additional marker for epidemiological analysis.

Cleavage of immunoglobulin A1, A2 and G by proteases from clinical isolates of Pasteurella multocida.

Several Pasteurella multocida strains were examined for their ability to produce extracellular enzymes that cleave immunoglobulin A and G (Ig A and Ig G) molecules. Two strains isolated from human pulmonary and genital infections produced proteases that cleaved human IgA and IgG, colostral IgA and human myeloma IgA1 and IgA2. Human IgM was not degraded by these enzymes. Examination of cleavage digests showed two main fragments with different electrophoretic mobilities. The two P. multocida strains produced a protease that cleaved IgA and IgG heavy chains outside the hinge region, and differed in this respect from the hinge-cutting proteases of other bacteria. Protease production may be a virulence mechanism for P. multocida strains.

Continuous ambulatory peritoneal dialysis: evaluation of three new culture methods.

Out of 900 dialysates analysed over 15 months at the Rennes Regional Hospital, 116 cloudy specimens with a leucocyte count of more than 100/mm3 were studied. Three methods of laboratory diagnosis based on physical or chemical disruption of leucocytes were evaluated: saponin incorporated in the agar medium, sonication, and the Isolator lysis centrifugation system. Sensitivity was improved (52%) for the three methods combined compared with the standard method (37%). The Isolator system (51%, P < 0.05) gave the best results. Direct microscopic examination nevertheless remains essential for its indicative value (sensitivity 33% of positive dialysates). The leucocyte count was correlated with the percentage of culture positivity (43% from 100-200/mm3 compared with 62% from 500-1000/mm3); 80% of organisms were Gram-positive bacteria and most were coagulase-negative staphylococci. Opportunistic pathogens such as Corynebacterium jeikeium were frequently isolated.

[Evolution of antibiotic resistance and serogroups of Streptococcus pneumoniae over the 1997-2003 period in Brittany]. / Evolution de la résistance aux antibiotiques et des sérogroupes de Streptococcus pneumoniae en Bretagne entre 1997 et 2003.

At this time, many antibiotics have decreased activity against Streptococcus pneumoniae, a major agent of infectious disease. In this study, we evaluated antibiotic susceptibility and serogroups of strains isolated from bacteraemia, meningitis and acute otitis media in adults and children over the 1997-2003 period in Brittany, France. In 2003, 62% of the isolates were not susceptible to penicillin and 11% were fully resistant. The prevalence of erythromycin resistance was 63%. Resistance rates were higher among isolates recovered from children than adults. Serogroups 19 and 14 were the most frequently isolated, especially the 19 one among children. The emergence of this serogroup might be a consequence of the use of heptavalent conjugate vaccine introduced in 2001 in France. Future surveillance after vaccination will be needed to detect emerging serogroups and resistance among S. pneumoniae.

Selective medium for Pasteurella multocida and its use to detect oropharyngeal carriage in pig breeders.

A selective culture medium for isolation of Pasteurella multocida was prepared by incorporating 2 mg of amikacin per liter, 4 mg of vancomycin per liter, and 4 mg of amphotericin B per liter into Mueller-Hinton blood agar. Use of this medium revealed the presence of P. multocida in the oropharynges of 19 of the 49 pig breeders who were examined.

Inhibitor-resistant OXY-2-derived beta-lactamase produced by Klebsiella oxytoca.

Klebsiella oxytoca strains are generally moderately resistant to amoxicillin and ticarcillin due to the activities of the chromosomally encoded OXY-1 and OXY-2 class A beta-lactamase families. These enzymes have the ability to hydrolyze not only penicillins but also cephalosporins, including cefuroxime, ceftriaxone, and aztreonam, and are inhibited by clavulanic acid. A Klebsiella oxytoca strain was isolated from a culture of blood from a patient who had been treated with amoxicillin-clavulanate (3 g/day) for 10 days 1 month earlier. This strain harbored an unusual phenotype characterized by resistance to amoxicillin-clavulanate. It produced an OXY-2-type beta-lactamase (pI 6.3), as confirmed by PCR amplification with primers specific for the OXY-2-encoding gene. Gene sequencing revealed a point mutation (A-->G) corresponding to the amino acid substitution Ser-->Gly at position 130. This mutant enzyme was poorly inhibited by inhibitors, and its kinetic constants compared to those of the parent enzyme were characterized by an increased Km value for ticarcillin, with a drastically reduced activity against cephalosporins, as is observed with inhibitor-resistant TEM enzymes. The substitution Ser-->Gly-130 was previously described in the inhibitor-resistant beta-lactamase SHV-10 derived from an SHV-5 variant, but this is the first report of such a mutant in OXY enzymes from K. oxytoca.

Pasteurella multocida: oropharyngeal carriage and antibody response in breeders.

The presence of Pasteurella multocida in the oropharynx of 58 pig, cattle or rabbit breeders whose livestock had suffered from pasteurellosis was investigated using a selective medium. Blood samples for serological studies were collected at the same moment. Nineteen breeders were found to host one P multocida subsp multocida strain. Oropharyngeal carriage of P multocida was found to be more frequent in pig breeders (42% of individuals) than in cattle (10%) or rabbit (0%) breeders. Genomic polymorphism among 10 D2 strains was found by restriction endonuclease analysis using pulsed-field gel electrophoresis (REA-PFGE). Antibodies to P multocida were found in the sera of 32 of these 58 breeders, whereas only 2 of the 70 controls had antibodies. These results, recorded from healthy individuals, show that P multocida, acting as an opportunistic bacterium, may be responsible for occupational diseases. Nevertheless, the strong prevalence of specific antibodies makes the presence of antibodies in the sera of these breeders an insufficient indication of a current patent infection.

[Helicobacter pylori gastritis manifested by acute anemia]. / Anémie aiguë révélatrice d'une gastrite à Helicobacter pylori.

Helicobacter pylori gastritis usually manifests as recurrent abdominal pain but is sometimes discovered upon evaluation for digestive tract bleeding with severe anemia. An 11-year-old who was not under medication and had no history of pain was admitted for isolated regenerative anemia (5.6 g/dl) due to digestive tract bleeding. Laboratory tests showed only low serum iron and ferritin levels. Endoscopy disclosed hemorrhagic inflammation of the duodenal cap and antritis with a hillocky appearance. The diagnosis of H. pylori infection was established on the basis of the finding of curved Gram-negative rods on the smears and of a positive urea test. There was moderate interstitial antritis. The patient was given an H2 antagonist (ranitidine) and amoxicillin with tinidazole for six weeks. Serum IgG antibodies against H. pylori were found in the child's parents and siblings, with the exception of a 7 month old infant. A ten year old sister had been hospitalized two years earlier for hemorrhagic duodenitis ascribed at the time to use of acetylsalicylic acid. H. pylori has been reported in 40% to 95% of pediatric patients with primary gastritis. Physicians should be familiar with this frequent, often familial disease. Management rests on concomitant administration of two antimicrobials and an acid secretion inhibitor to the index patient and family members. Endoscopy is too invasive to be appropriate for monitoring the outcome. In practice, recovery is affirmed on the basis of resolution of clinical manifestations and decreased levels of anti-H. pylori antibodies.

Septicemia and hepatic abscess caused by Pediococcus acidilactici.

A case of postoperative Pediococcus acidilactici septicemia with parallel isolation of the organism from hepatic specimens is presented. Laboratory methods to identify this vancomycin-resistant gram-positive cocci are described. Very few cases of documented infections due to this bacterium have been reported in the literature.

[Antibiotics resistance of Streptococcus pneumoniae. Results from the Brittany registry for 1999]. / Etat de la résistance aux antibiotiques de Streptococcus pneumoniae dans la région Bretagne. Résultats de l'Observatoire Régional du Pneumocoque pour l'année 1999.

Throughout 1999, clinical microbiology laboratories of 13 hospitals in Brittany have recovered Streptococcus pneumoniae isolates in 832 patients, 312 (37.5%) female and 518 (62.2%) male. Two hundred fifty five of them (30.6%) were children. One hundred eighty eight isolates were recovered from blood cultures (22.6%), 16 from CSF (1.9%), 449 from lungs (54%), and 88 from ear exsudates (10.6%).A 5 microgram oxacillin-disk test was used to detect isolates with reduced susceptibility to penicillin G. Determination of MICs of penicillin G, amoxicillin and cefotaxime were then performed by agar dilution method on 402 strains previously categorized resistant or intermediate. Five hundred forty six isolates were PSDP, 33.5% of them were resistant to penicillin G, 2.2% to amoxicillin and 0.2% to cefotaxime. As expected, a decreased susceptibility to beta-lactamins was frequently associated with resistance to macrolides, cotrimoxazole and tetracycline. Among PSDP, the most prevalent serotypes were 23 (23.7%), 14 (23.5%) and 19 (19.1%). In Brittany, the constant rise of PSDP (1993-1994: 28.5%; 1997: 56.4%; 1999: 65.6 %) could be perhaps explain by analysis of social and demographic data.