- Volume 61, Issue 8, 2012

Pseudomonas aeruginosa is a Gram-negative bacterium commonly occurring in soil and water. It is an opportunistic pathogen and an important cause of healthcare-associated infections, particularly among infants in neonatal intensive care units (NICUs). Several reports regarding outbreaks of P. aeruginosa in NICUs have been published. MEDLINE and EMBASE databases were searched using the MeSH terms [Pseudomonas aeruginosa], [Outbreak OR Infection OR bacteraemia, OR sepsis OR disease] and [Neonat* OR baby OR babies OR newborn*]. Fifteen studies describing a total of 414 infants colonized or infected with P. aeruginosa were reviewed. The mean percentage of infections occurring in the populations that had been colonized by the organism (calculated as n infected/n infected+n colonized) was 22 %. Environmental sampling was performed in 14 studies, nine of which detected P. aeruginosa. The risk factors identified were antimicrobial drug use and the number of days of antimicrobial therapy prescribed before positive blood culture, exposure to particular healthcare workers (HCW), transfusion of blood products, and intravenous delivery of nutrients/electrolytes. Exposure to umbilical venous catheters was associated with bloodstream infections. Increasing age and use of artificial fingernails were risk factors for colonization of hands of HCWs. Low birth weight pre-term infants were at greater risk of mortality from P. aeruginosa infection than older infants.

Cholera toxin (CT) is the major virulence factor produced by Vibrio cholerae. Several genomic arrangements within the CTX cassette have been elucidated in V. cholerae. Previously, it was shown that three different CTX cassette arrangements, one complete CTX cassette (arrangement A), one complete and two incomplete CTX cassettes (arrangement B), and two complete CTX cassettes (arrangement C), exist within V. cholerae isolates. In the present study, the level of CT expression by V. cholerae isolates carrying different CTX cassette arrangements was evaluated. Real-time quantitative PCR analysis showed unequal production of CT mRNA in V. cholerae isolates with different CTX arrangements. V. cholerae with the CTX arrangement C expressed more CT mRNA than isolates with the other CTX arrangements. In addition, CT mRNA was expressed more in the isolates with CTX arrangement B than in those with arrangement A. Overall, these results suggest that the arrangement and number of regulatory elements (rstA) within the CTX cassette could affect the level of expression of CT.

The objectives of the present study were to evaluate in vitro the production of antagonistic compounds against Gardnerella vaginalis by Lactobacillus strains isolated from women with or without bacterial vaginosis (BV), and to select one of the better Lactobacillus producers of such a substance to be tested in vivo using a gnotobiotic animal model challenged with one of the more sensitive G. vaginalis isolates. A total of 24 isolates from women with and without BV were identified as G. vaginalis. A higher frequency (P<0.05) of this bacterium was observed in women with BV (56.7 %) when compared to healthy women (17.6 %). A total of 86 strains of Lactobacillus were obtained from healthy women and women with BV. Lactobacillus strains were more frequently present (P<0.05) in healthy women (97.5 %) than in women with BV (76.7 %). Lactobacillus crispatus was the predominating strain in both healthy women and women with BV. Lactobacillus jensenii, Lactobacillus johnsonii, Lactobacillus gasseri and Lactobacillus vaginalis were isolated with an intermediate frequency in the two groups. In vitro antagonism assays were performed using as indicators 17 reference strains and the G. vaginalis strains isolated from women with BV and from healthy women. Lactobacillus isolated from healthy women showed the higher antagonistic activity against all the indicator strains when compared with isolates from women with BV. Concerning the indicator strains, G. vaginalis found in women with BV was more resistant to the antagonism, particularly when Lactobacillus isolates from women with BV were used as producer strains. A high vaginal population level of G. vaginalis was obtained by intravaginal inoculation of germ-free mice, and this colonization was accompanied by vaginal histopathological lesions. A tenfold decrease in vaginal population level of G. vaginalis and a reduction of histological lesions were observed when the pathogenic challenge was performed in mice previously monoassociated with an L. johnsonii strain. Concluding, results of the present study suggest that progression of G. vaginalis-associated BV depends in part on a simultaneous presence of Lactobacillus populations with a low antagonistic capacity and of a G. vaginalis strain with a high resistance to this antagonism. The results could also explain why G. vaginalis is frequently found in the vaginal ecosystem of healthy women.

A real-time PCR assay targeting the cylB gene was developed to detect Streptococcus agalactiae [Lancefield group B Streptococcus (GBS)] from clinical samples. A total of 110 blood culture-negative samples [75 cerebrospinal fluid (CSF) and 35 EDTA blood samples] from neonates with probable GBS sepsis or meningitis were analysed. Among these, 16 of the 75 CSF samples were positive [21.3 %, 95 % confidence interval (CI) 12.7–32.3 %] and two of the 35 EDTA blood samples were positive (5.7 %, 95 % CI 0.7–19.2 %). The proportion testing positive in the CSF samples was significantly higher than in the EDTA blood samples (P = 0.05, Fisher’s exact test). Overall, this real-time PCR assay was shown to be superior to culture methods for detection of GBS from CSF and EDTA blood samples.

Candida albicans and Candida glabrata are the most common causative agents of both vulvovaginal candidiasis (VVC) and recurrent vulvovaginal candidiasis (RVVC). Studying the population structure and genotype differentiation of Candida species that cause RVVC may lead to a significant improvement in clinical management. A total of 106 isolates were collected from 55 patients who were subdivided into three groups. Group I comprised 15 patients with RVVC (n = 50 isolates); group II comprised 16 patients, who had a history of at least two episodes of VVC in the last year (n = 32 isolates, two from each patient); and group III comprised 24 patients (n = 24 isolates) who had experienced a single episode of VVC in the previous 1 year period. C. albicans microsatellite markers CAI, CAIII and CAIV and C. glabrata RPM2, MTI and ERG3 microsatellites were amplified in a multiplex PCR. All isolates were subjected to population genetic analysis, which provided evidence that there is a predominantly clonal population structure of C. albicans in each group. However, recombination was detected to some degree in C. albicans isolates in group III. A genetic homogeneity between the different C. albicans groups was observed. Although, C. glabrata isolates showed an important genetic differentiation between group I and group III (FST = 0.207). Genotype analysis revealed that the dominant genotypes of C. glabrata and C. albicans strains were more prevalent in patients with RVVC. The frequent scenario for cases of recurrent infection in our study was strain replacement (53.3 %). In conclusion, the identification of recurrence-associated genotypes and a specific C. glabrata population structure in the RVVC group could be a significant marker for further investigations of virulence factors and RVVC management.

A novel recombinant human adenovirus (HAdV) species D was isolated from the stool of a pharyngitis patient in Japan and genetic characterization was performed by sequencing variable regions between HAdV types. The nucleotide sequences of the penton base gene and loops 1 and 2 in the hexon gene showed 100 % identity with that of the recently identified HAdV-56. Although we observed greatest identity for the entire hexon gene sequence with that of HAdV-56, we noted even greater similarity between the partial nucleotide sequence of the conserved region 4 and that of HAdV-37. Furthermore, the fibre gene and early region 3 sequences were completely identical to that of HAdV-37. These results suggest that the strain is a novel adenovirus related to HAdV-37 and HAdV-56.

Between 2007 and 2009, 226 clinical strains of Streptococcus agalactiae, recovered from female genital specimens and from gastric fluid or ear specimens from infected newborns, were isolated at the Laboratory of Microbiology of Charles Nicolle Hospital of Tunis. They were investigated to determine the prevalence of antibiotic resistance and to characterize the mechanisms of resistance to macrolide and tetracycline. All strains were susceptible to penicillin, ampicillin and quinupristin–dalfopristin. They were resistant to chloramphenicol (3.1 %), rifampicin (19.1 %), erythromycin (40 %) and tetracycline (97.3 %); 3.1 % were highly resistant to streptomycin and 1.3 % to gentamicin. Among the erythromycin-resistant isolates, 78.7 % showed a constitutive macrolide–lincosamide–streptogramin B (MLSB) phenotype with high-level resistance to macrolides and clindamycin (MIC50 >256 µg ml−1), 10 % showed an inducible MLSB phenotype with high MICs of macrolides (MIC50 >256 µg ml−1) and low MICs of clindamycin (MIC50 = 8 µg ml−1) and 2.2 % showed an M phenotype with a low erythromycin-resistance level (MIC range = 12–32 µg ml−1) and low MICs of clindamycin (MIC range: 0.75–1 µg ml−1). All strains were susceptible to quinupristin–dalfopristin and linezolid (MIC90: 0.75 µg ml−1 for each). MLSB phenotypes were genotypically confirmed by the presence of the erm(B) gene and the M phenotype by the mef(A) gene. Resistance to tetracycline was mainly due to the tet(M) gene (93.1 %) encoding a ribosome protection mechanism. This determinant is commonly associated with the conjugative transposon Tn916 (P≤0.0002). tet(O) and tet(T) existed in a minority (2.2 % and 0.4 %, respectively). The efflux mechanism presented by tet(L) was less frequently present (4.5 %). No significant association was found between erm(B) and tet(M) genes.

This study was conducted to investigate the molecular characteristics and genetic relatedness of vancomycin-resistant Enterococcus faecium (VREF) isolates obtained from humans and poultry in Korea. A total of 147 VREF isolates from humans (71 clinical isolates) and poultry (76 isolates) in Korea were compared with respect to their antibiotic susceptibilities, organization of the Tn1546 transposon element, detection of virulence genes (esp and hyl), pulsed-field gel electrophoresis (PFGE) typing and multilocus sequence typing (MLST). All of the human and poultry isolates had the vanA gene and 11.3 % (8/71) of the clinical isolates showed the VanB phenotype/vanA genotype. PCR mapping of the Tn1546 elements was different for isolates of the two groups: human isolates were classified into five transposon types, whereas all poultry isolates were identical to Tn1546 of E. faecium strain BM4147. The esp gene was detected in both human (93.0 %, 66/71) and poultry (26.3 %, 20/76) isolates, as was the hyl gene (human isolates: 80.3 %, 57/71; poultry isolates: 26.3 %, 20/76). Using MLST, the 71 human isolates could be divided into ten sequence types (STs) belonging to clonal complex (CC) 17 (except for one singleton). The 76 poultry isolates were categorized into 14 STs and 88.2 % (67/76) of the poultry isolates belonged to CC26. PFGE typing of the human isolates demonstrated diverse PFGE profiles among the strains. However, the PFGE patterns of the poultry isolates were possibly related to the strains collected from individual farms. These data suggest that epidemic clonal groups of human and poultry VREFs in Korea have evolved through different evolutionary processes.

A total of 108 coagulase-negative staphylococci (CoNS) were collected from hospital indoor air. The majority of the isolates were able to produce biofilms and displayed multiresistance profiles. The most frequent species identified were Staphylococcus epidermidis (n = 27) and Staphylococcus haemolyticus (n = 17). Potential virulence traits (icaAD, aap, hld, atlE and sesB) and genotypic profiles were compared for S. epidermidis isolates from indoor air (n = 27) and from patients (n = 26) who had been admitted to the hospital 8–34 months after air sampling. Overall, the virulence factors tested were more frequently found among S. epidermidis recovered from clinical origin than from air sources (P = 0.003). Indeed, the group of patient isolates exhibited superior ability to accumulate biofilms (P<0.0001). Despite this, genotyping using PFGE revealed that identical clones of S. epidermidis could be recovered from both patient and indoor air samples. In addition, some airborne isolates displayed virulence profiles and levels of biofilm accumulation similar to those found in patient isolates. Therefore, further studies are necessary to clarify the importance of hospital indoor air as a route of transmission for CoNS isolates (mainly S. epidermidis).

We report what is believed to be the first case of pulmonary Actinomyces graevenitzii infection presenting as organizing pneumonia. Fever and night sweats developed in a 69-year-old male. The only abnormal laboratory data were an elevated erythrocyte sedimentation rate and C-reactive protein level. On chest images, multiple consolidations with air bronchograms were seen in the bilateral lungs. Histological examination from lung biopsy revealed a pattern of organizing pneumonia with microabscesses, but definitive diagnosis was not obtained because culture from lung specimen was negative. A . graevenitzii was eventually identified in the lung biopsy specimen by detection of an Actinomyces-specific PCR product followed by 16S rRNA gene sequencing. The patient was treated with high-dose ampicillin intravenously for 1 month, followed by oral amoxicillin and clarithromycin for 6 months, and recovered. We suggest that actinomycosis can present as organizing pneumonia, and identification of infection by PCR analysis and rRNA gene sequencing is a useful strategy in cases that are difficult to diagnose.

We report a rare case of infective endocarditis caused by Corynebacterium diphtheriae in an 8-year-old boy, 2 years after a right ventricular outflow tract reconstruction with a bovine Contegra valved conduit. The patient recovered well after an RV–PA conduit enblock explantation and replacement with an aortic homograft with antibiotic treatment. All bacteriological cultures of excised tissue and blood were negative. The aetiological agent was identified as C. diphtheriae subsp. gravis by 16s rDNA sequencing.

Here, we present a case of an 85-year-old woman with a low-grade-infection caused by Actinomyces naeslundii after total-knee arthroplasty (TKA) followed by septic loosening. Actinomyces naeslundii was cultured from a tissue sample from the knee joint capsule/synovial tissue obtained after the initial TKA. A review of the literature revealed two cases of periprosthetic infection and another three cases of arthritis due to Actinomyces naeslundii. So far, no standard treatment for periprosthetic infections caused by Actinomyces species has been established.