P. Cocchi

Features of children perinatally infected with HIV-1 surviving longer than 5 years. Italian Register for HIV Infection in Children

Children infected with HIV do not necessarily develop AIDS to a set pattern but can be divided into long-term and short-term survivors. We examined long-term survival in children perinatally infected with HIV-1. Out of a total of 624, we studied 182 children who survived longer than 5 years (long-term survivors [LTS]) and 120 children who died of HIV-1-related disease before 5 years (defined as short-term survivors [STS]). 28 (15%) LTS were symptomless (Centers for Disease Control [CDC] P-1 children). 154 (85%) had symptoms (CDC P-2). The proportion of LTS with less than 0.2 x 10(9)/CD4 cells per L was 24/116 (21%) at 61-72 months, rising to 11/26 (41%) at more than 96 months. On at least one occasion, p24 antigenaemia was observed in 112 (62%) LTS. Annual rate of CD4 cell loss was lower in LTS (25% [95% CI: 21-29]) than in STS (53% [45-60]) and in LTS symptomless or with solitary P-2A signs (17%; [13-21]) than in LTS with severe manifestations (30% [25-35]). A new outlook emerges. A substantial number of children do survive after early childhood; severe diseases; low CD4 cell numbers, and p24 antigenaemia do not necessarily preclude long-term survival. The study shows that a CD4 cell decrease early in life can be predictive of outcome.

NITROBLUE-TETRAZOLIUM REDUCTION BY NEUTROPHILS OF NEWBORN INFANTS IN IN VITRO PHAGOCYTOSIS TEST

Venous blood from healthy premature infants, premature infants with known bacterial infections, normal term infants and adults, was incubated in vitro with Pseudomonas aeruginosa. At 30 min intervals, blood samples were tested for the nitroblue‐tetrazolium (NBT) reducing activity of neutrophils. The results of the histochemical NBT test were compared with those of the blood controls from which bacteria were omitted.

MENINGITIS CAUSED BY NEISSERIA CATARRHALIS

A case is reported of meningitis due to Neisseria catarrhalis in a 14‐month‐old infant. The organism was cultured from the spinal fluid and throat. The patient recovered after penicillins, erythromycin and chloramphenicol therapy.

Molecular epidemiology of meticillin-resistant Staphylococcus aureus in Italian cystic fibrosis patients: A national overview

BACKGROUND The genetic background, transmissibility and virulence of MRSA have been poorly investigated in the cystic fibrosis (CF) population. The aim of this multicentre study was to analyse MRSA strains isolated from CF patients attending nine Italian CF care centres during a two-year period (2004-2005). All CF patients infected by MRSA were included. METHOD Antibiotic susceptibility testing, SCCmec typing, Panton-Valentine Leukocidin (PVL) production, and Multi Locus Sequence Typing (MLST) analysis were carried out on collected isolates (one strain per patient). RESULTS One hundred and seventy-eight strains isolated from 2360 patients attending the participating centres were analysed. We detected 56 (31.4%) SCCmec IV PVL-negative strains, with a resistance rate of 80.3% to clindamycin and of 14.5% to trimethoprim/sulphamethoxazole. MLST analysis showed that many isolates belonged to known epidemic lineages. The largest clone grouping of 29 isolates from 6 centres had the genetic background (ST8-MRSA-IV) of the American lineages USA300 and USA500, thus demonstrating the diffusion of these strains in a population considered at risk for hospital associated infections. CONCLUSIONS Known MRSA epidemic clones such as USA600, USA800, USA1100, and UK EMRSA-3 were described for the first time in Italy. The diffusion of MRSA strains with high pathogenic potential in the CF population suggests that analysis of the MRSA strains involved in pulmonary infections of these patients is needed.

Use of the gyrB gene to discriminate among species of the Burkholderia cepacia complex

Bacteria of the Burkholderia cepacia complex (Bcc) are opportunistic pathogens that can cause serious infections in lungs of cystic fibrosis patients. The Bcc comprises at least nine species that have been discriminated by a polyphasic taxonomic approach. In this study, we focused on the gyrB gene, universally distributed among bacteria, as a new target gene to discriminate among the Bcc species. New PCR primers were designed to amplify a gyrB DNA fragment of about 1900 bp from 76 strains representative of all Bcc species. Nucleotide sequences of PCR products were determined and showed more than 400 polymorphic sites with high sequence similarity values from most isolates of the same species. Phylogenetic tree analysis revealed that most of the 76 gyrB sequences grouped, forming clusters, each corresponding to a given Bcc species.

Emergence of an epidemic clone of community-associated methicillin-resistant panton-valentine leucocidin-negative Staphylococcus aureus in cystic fibrosis patient populations.

The article by Moroney et al. (3) documents the increased prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains in different patient populations. Most of the CA-MRSA strains characterized by carriage of staphylococcal cassette chromosome mec (SCCmec) type IV were also positive for the Panton-Valentine leucocidin (PVL) gene 1 (2). However, this gene association is not necessarily indicative of CA-MRSA strains. We analyzed the prevalence and molecular epidemiology of MRSA from the airways of cystic fibrosis (CF) patients in an Italian multicenter study. One hundred eighty-one (7.6%) out of 2,362 CF patients attending 9 Italian CF centers were infected with MRSA. A high prevalence (36%) of SCCmec IV (suggestive of CA-MRSA strains) was found (5). Pulsed-field gel electrophoresis analysis showed a single MRSA clone colonizing 31 patients in 6 centers. Twenty-four out of 31 strains (77.4%) revealed SCCmec type IV, mostly associated with CA-MRSA. All the SCCmec type IV MRSA isolates belonging to the epidemic clone were negative for the PVL genes, as reported by other authors (4). The high prevalence of MRSA strains, suggestive of CA-MRSA in a patient population considered at risk for hospital-associated (HA)-MRSA acquisition, is worrisome evidence supporting current opinions that CA-MRSA strains are replacing HA-MRSA strains in health care settings (1, 6). The interesting question of whether the CA-MRSA clone infected the CF patients in the community or whether the patients acquired the clone in the hospital which they attended regularly is unclear and needs to be further studied.

Serratia marcescens outbreak in a neonatal intensive care unit: crucial role of implementing hand hygiene among external consultants.

BackgroundSerratia marcescens represents an important pathogen involved in hospital acquired infections. Outbreaks are frequently reported and are difficult to eradicate. The aim of this study is to describe an outbreak of Serratia marcescens occurred from May to November 2012 in a neonatal intensive care unit, to discuss the control measures adopted, addressing the role of molecular biology in routine investigations during the outbreak.MethodsAfter an outbreak of Serratia marcescens involving 14 neonates, all admitted patients were screened for rectal and ocular carriage every two weeks. Extensive environmental sampling procedure and hand sampling of the staff were performed. Antimicrobial susceptibility pattern and molecular analysis of isolates were carried out. Effective hand hygiene measures involving all the external consultants has been implemented. Colonized and infected babies were cohorted. Dedicated staff was established to care for the colonized or infected babies.ResultsDuring the surveillance, 65 newborns were sampled obtaining 297 ocular and rectal swabs in five times. Thirty-four Serratia marcescens isolates were collected: 11 out of 34 strains were isolated from eyes, being the remaining 23 isolated from rectal swabs. Two patients presented symptomatic conjunctivitis. Environmental and hand sampling resulted negative. During the fifth sampling procedure no colonized or infected patients have been identified. Two different clones have been identified.ConclusionsOcular and rectal colonization played an important role in spread of infections. Implementation of infection control measures, involving also external specialists, allowed to control a serious Serratia marcescens outbreak in a neonatal intensive care unit.

Application of multiplex single nucleotide primer extension (mSNuPE) to the identification of bacteria: the Burkholderia cepacia complex case.

Burkholderia cepacia complex (BCC) is characterized by a complex taxonomy constituted by seventeen closely related species of both biotechnological and clinical importance. Several molecular methods have been developed to accurately identify BCC species but simpler and effective strategies for BCC classification are still needed. A single nucleotide primer extension (SNuPE) assay using gyrB as a target gene was developed to identify bacteria belonging to the B. cepacia (BCC) complex. This technique allows the successful detection and distinction of single nucleotide polymorphisms (SNPs) and is effectively applied in routine medical diagnosis since it permits to analyze routinely many samples in a few times. Seven SNuPE primers were designed analyzing the conserved regions of the BCC gyrB sequences currently available in databases. The specificity of the assay was evaluated using reference strains of some BCC species. Data obtained enabled to discriminate bacteria belonging to the species B. multivorans, B. cenocepacia (including bacteria belonging to recA lineages III-A, III-C, and III-D), B. vietnamiensis, B. dolosa, B. ambifaria, B. anthina and B. pyrrocinia. Conversely, identification failed for B. cepacia, B. cenocepacia III-B and B. stabilis. This study demonstrates the efficacy of SNuPE technique for the identification of bacteria characterized by a complex taxonomical organization as BCC bacteria.

Severe infections caused by Panton-Valentine leukocidin-positive Staphylococcus aureus in infants: report of three cases and review of literature.

We report three cases of severe infections in infants caused by Panton–Valentine leukocidin positive Staphylococcus aureus and evolved with a positive outcome. The literature of Panton–Valentine leukocidin positive Staphylococcus aureus infections in infants is reviewed.

Evidence of transmission of a Panton-Valentine leukocidin-positive community-acquired methicillin-resistant Staphylococcus aureus clone: a family affair

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) may represent a serious public health problem, owing to the spread of toxin-producing lineages. The presence of genes encoding for Panton-Valentine leukocidin (PVL) is an important virulence marker, as the clinical sequelae of PVL-positive infections are often described as more severe than those of PVL-negative S. aureus infections. To date, the presence of PVL has not appeared to be common in Italy; we describe the intrafamilial transmission of an epidemic PVL-producing CA-MRSA lineage, Southwest Pacific clone (SWP). Our data suggested that the strain circulated from the father, who was recurrently affected by a soft tissue infection, to the mother, who showed nasal colonization, and to their child, who was hospitalized with symptoms of necrotizing pneumonia. In this case, we found that a recurrent skin infection that is not normally taken into account may represent a serious threat if caused by a PVL-producing strain. Our findings may have considerable implications for strategies for infection control and treatment of methicillin-resistant S. aureus infections.