Duodenal microflora in very-low-birth-weight neonates and relation to necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in the neonatal period. Small-bowel overgrowth with aerobic gram-negative bacteria has previously been implicated in the development of NEC. This prospective study performed quantitative bacteriology on 422 duodenal aspirates collected from 122 very-low-birth-weight (<1,500-g) newborns, at the time of routine changing of nasogastric tubes. Isolates of Enterobacteriaceae were typed by repetitive extragenic, palindromic PCR and pulsed-field gel electrophoresis. One or more samples from 50% of these infants yielded gram-negative bacteria, predominantly Escherichia coli, Klebsiella spp., and Enterobacter spp., with counts up to 10(8) CFU/g. The proportion of samples with gram-negative bacteria increased with postnatal age, while the percentage of sterile samples declined. Molecular typing revealed marked temporal clustering of indistinguishable strains. All infants had been fed prior to isolation of gram-negative organisms. Antibiotic use had no obvious effect on colonization with Enterobacteriaceae. There were 15 episodes of suspected NEC (stage I) and 8 confirmed cases of NEC (2 stage II and 6 stage III) during the study period. Duodenal aspirates were collected prior to clinical onset in 13 episodes of NEC. Seven of these yielded Enterobacteriaceae, of which five strains were also isolated from infants without NEC. Very-low-birth-weight infants have high levels of duodenal colonization with Enterobacteriaceae, with evidence of considerable cross-colonization with indistinguishable strains. There was no association between duodenal colonization with particular strains of Enterobacteriaceae and development of NEC.

Combined cervical swab and urine specimens for PCR diagnosis of genital Chlamydia trachomatis infection.

OBJECTIVES: Sampling of both the cervix and urine increases the chance of detection of Chlamydia trachomatis compared with sampling either site alone. We determined the effect of combining urine and cervical swab specimens in the clinic setting on the sensitivity of C trachomatis polymerase chain reaction (PCR) testing. METHODS: For each of 100 women attending a genitourinary medicine clinic with high likelihood of genital C trachomatis infection, one endocervical swab was placed in transport medium and another in one of two aliquots of first void urine. Four PCR assays per patient (urine + swab, swab alone, and urine alone both pre- and post-freeze-thawing) were processed by automated C trachomatis PCR (Cobas, Amplicor). An inhibition control was included with each assay to identify specimens containing PCR inhibitors. RESULTS: 71% of women were Amplicor C trachomatis PCR positive (according to the results of at least one specimen). PCR test results were concordant for 95/100 patients, and of the five discordant result sets there was only one major discrepancy. Inhibitors of PCR were present in 22/400 specimens from 20 patients, and 16/22 were cervical swabs (p < 0.001). CONCLUSIONS: Combining a cervical swab with a urine specimen is acceptable for PCR testing for genital C trachomatis infection, and has the potential to increase further the cost effectiveness of DNA based screening for C trachomatis genital infection.

Protein movement across cultured guinea pig trachea: specificity and effect of transcytosis inhibitors.

Airway surface liquid (ASL) is a complex fluid with solutes including electrolytes, lipids, mucins, and proteins. The proximal airways are absorptive for most solutes, including proteins. We investigated the process of protein movement across confluent primary cultures of guinea pig trachea grown on filters using fluorescent-labeled bovine serum albumin (BSA), ovalbumin (OA), and 70-kDa dextran (Dex). We found marked asymmetry of BSA and OA transepithelial flux, with apical-to-basolateral flux (JA-->B) 10 times greater than the opposite direction (JB-->A) for both proteins. The apparent permeability for Dex was the same as that for proteins in the basolateral-to-apical direction and showed no asymmetry. Increasing concentrations of unlabeled BSA, OA, or transferrin inhibited JA-->B for both BSA and OA without affecting Dex movement. Cooling reduced JA-->B for BSA without affecting JB-->A. Monensin and nocodazole each reduced JA-->B for BSA and OA without affecting JB-->A. Monensin eliminated all asymmetry for BSA movement. Brefeldin A did not affect JA-->B for either protein but did increase JB-->A for BSA. Treatment with the protease inhibitors increased JA-->B for BSA. Western immunoblotting demonstrated immunologically intact protein in the downstream compartment. We conclude that there is transcytosis of proteins across cultured trachea epithelium in the apical-to-basolateral direction, which is monensin sensitive, involves microtubules, is not dependent on proteolysis, and is not protein species specific. This process may be important for maintenance of the ASL, and defects in this process may contribute to the abnormally thickened airway secretion seen in airway diseases.

Rapid diagnosis of central venous catheter sepsis.

Signs of infection with a central venous access device in situ raise the possibility of catheter sepsis. We evaluated three tests for diagnosis of infection in infants with suspected catheter sepsis. The acridine orange leucocyte cytospin (AOLC) test was 87% sensitive and 94% specific in the diagnosis of catheter-related sepsis defined by quantitative blood culture. The C-reactive protein and nitroblue tetrazolium tests were not as useful. Using the AOLC results, available in an hour, we now remove fewer catheters on suspicion of sepsis alone.

Treatment of relapsing experimental autoimmune encephalomyelitis with T cell receptor peptides.

Restricted T cell receptor (TCR) VB gene usage by T cells for recognition of antigens involved in the production of experimental autoimmune encephalomyelitis (EAE) offers the possibility of selective immunotherapy. We determined the preferential VB gene usage of lymph node-derived clones from SJL/J mice to recognize the encephalitogenic epitope PLP 139-151 and from PL/J mice to recognize the newly described encephalitogenic epitope PLP 43-64. In addition, the VB gene usage for recognition of PLP 139-151 by T cell lines derived from SJL/J spinal cords was analyzed. Lymph node-derived SJL/J lines and clones specific for PLP 139-151 expressed VB2, VB4, and VB17a preferentially, and PL/J lines and clones specific for PLP 43-64 expressed VB2 and VB8.2 preferentially. A VB4 + SJL/J clone and a VB8.2 + PL/J clone were encephalitogenic. Encephalitogenic SJL/J lines derived from spinal cord expressed VB2, VB10, VB16, and VB17a preferentially, with a predominance of VB2. Candidate TCR peptides were synthesized and tested from the VB gene families VB4, VB8.2, and VB17a, based on our data and previous data on BP-induced EAE in mice. Treatment of relapsing EAE (R-EAE) in SJL/J mice with VB4 and VB17a peptides reduced clinical and histological disease severity, and treatment of R-EAE in (PLxSJL)F1 mice with VB4 and VB8.2 peptides also reduced clinical and histological disease. The use of TCR peptide therapy may have applications for the treatment of human autoimmune diseases such as multiple sclerosis.

Co-existent cross-infection with Streptococcus pneumoniae and group B streptococci on an adult oncology unit.

An outbreak of respiratory infection in an adult oncology unit is described where there was evidence of co-existent cross-infection with Streptococcus pneumoniae serotype 14 and Lancefield group B streptococcus type Ia. The presumed route of transmission was droplet spread from patient to patient. No further cases arose after the ward had been closed to new admissions and all symptomatic patients were treated with erythromycin. We suggest that patients with pneumococcal pneumonia on units housing elderly debilitated patients should be isolated. Infection control teams should be aware of the ability of Lancefield group B streptococci to spread by cross-infection among adult patients.

Location of a new encephalitogenic epitope (residues 43 to 64) in proteolipid protein that induces relapsing experimental autoimmune encephalomyelitis in PL/J and (SJL x PL)F1 mice.

Synthetic peptides of proteolipid protein (PLP) were screened for their ability to induce experimental autoimmune encephalomyelitis (EAE) in SJL/J, PL/J, and (SJL x PL)F1 mice, and T cell lines were selected by stimulation of lymph node cells with PLP peptides. PLP 141-151 was found to be less encephalitogenic in SJL/J mice than PLP 139-151, due to deletion of two amino acids from the amino-terminal end. PLP 139-151 immunization induced relapsing EAE in SJL/J and F1 mice but not PL/J mice. In contrast, PLP 43-64 induced relapsing EAE in PL/J and F1 mice but not SJL/J mice. F1 T cell lines specific for either PLP 43-64 or PLP 139-151 adoptively transferred demyelinating EAE to naive F1 recipients. Haplotypes H-2s and H-2u appear to be immunologically co-dominant in F1 mice in the PLP EAE system, which differs from the H-2u dominance in F1 mice in the myelin basic protein EAE system. The identification of a PLP peptide that is encephalitogenic in PL/J mice, in addition to the previous demonstration of PLP peptides that are encephalitogenic for SWR mice (PLP 103-116) and SJL/J mice (PLP 139-151), lends support to a role for PLP as a target Ag in autoimmune demyelinating diseases.

Development of the transdermal potential of human skin.

The development of the transdermal electrical potential (TDP) with postnatal age was studied in neonates born at gestational ages of 25 to 42 wk. The TDP of neonates born at less than 28 wk gestational age was of similar magnitude over the whole skin surface when measured in the first 5 d of life (mean value -5.4 mV; skin surface negative with respect to s.c. tissues). The TDP increased progressively with increasing gestational and postnatal age. The rate of increase of the TDP with postmenstrual age was not accelerated in neonates born prematurely. TDP values of infants born at term were lower than those of adults, but the sites of high and low TDP were similar in both term infants and adults.