Role of catheter colonization and infrequent hematogenous seeding in catheter-related infections.

Adult cancer patients were prospectively studied to determine the relationship between ultrastructural and microbiologic catheter colonization and clinical catheter-related infections. Participants included 38 patients whose central venous catheters were removed because of suspected catheter infection (16 patients) or other noninfectious causes (22 controls). The presence of clinical infection was determined. Catheters were examined by microbiologic methods (sonication and roll-plate culture) and by scanning and transmission electron microscopy. Ultrastructural microbial colonization and biofilm formation were universal and occurred as early as one day after catheter insertion. The extent of biofilm formation was unrelated to the clinical status of patient or the catheter microbiological findings. Secondary seeding of catheters was rarely seen. Catheter microbial biofilm formation occurs early, is universal and does not necessarily represent an infectious condition.

Ultrastructural analysis of indwelling vascular catheters: a quantitative relationship between luminal colonization and duration of placement.

To assess the degree of luminal and extraluminal colonization of long-term central venous catheters (CVC), 359 indwelling silicone CVC from 340 consecutive cancer patients were examined. All CVC were cultured by the roll-plate and sonication quantitative culture techniques. Semiquantitative electron microscopy was done on 39 CVC associated with catheter infections and on 26 culture-negative controls. An additional 10 culture-negative CVC obtained after death were also studied by electron microscopy. Ultrastructural colonization and biofilm formation was universal and quantitatively independent of clinical catheter-related infections. Ultrastructural colonization and biofilm formation was predominantly luminal in long-term CVC (> 30 days). Based on a composite definition, the sensitivity of the roll-plate catheter tip culture was 42%-45% compared with 65%-72% for the sonication of the tip. Colonization of indwelling catheters is universal regardless of culture results. For long-term CVC, colonization becomes predominantly luminal and extraluminal quantitative catheter cultures are of limited diagnostic sensitivity.

Evaluation of sepsis screen for diagnosis of neonatal septicemia.

Fifty clinically suspected cases of neonatal septicemia were studied for evaluating the role of sepsis screen. Sensitivity and specificity of C-reactive protein test, micro-ESR, gastric aspirate cytology for polymorphs and toxic granules in neutrophils were studied singly and in combinations of two and three tests. Positive blood culture was obtained in only 20% cases, thereby underlying the need for a sepsis screen in the diagnosis of neonatal septicemia, especially in areas where adequate micro-biological facilities are lacking.

Diagnostic and prognostic role of CRP and m-ESR in neonatal septicemia.

Serial estimation of CRP and m-ESR was done in 65 clinically suspected cases of septicemia and 25 healthy controls. Of these 65, 12 (18%) had a negative CRP test at the time of diagnosis and rest all had significantly elevated CRP and m-ESR compared to matched controls at the time of diagnosis. A persistently negative CRP test indicated bad prognosis. With treatment a declining trend of CRP was seen in survivors, but in deteriorating/expired babies the levels kept on increasing. However, m-ESR had no prognostic significance.

Group B streptococci in IUCD users.

PIP: 200 women attending a family planning clinic for IUD insertion were surveyed for carriage of group B streptococci at various sites and to determine the effect of such device on the carriage rate. Group I comprised women who were coming for the 1st time (preinsertion); Group II were women already fitted with an IUD (postinsertion and followup). Urethral, vaginal, and rectal samples were taken from each woman with serum coated and cotton tipped swabs. Final identification was done by serological grouping of streptococci by Fuller's method. All the strains of group B streptococci were sent to the World Health Organization Collaborating Center for Reference and Training in Streptococcal Disease (New Delhi, India) for serotyping. The postinsertion group (8%) had higher carriage than the preinsertion group (5%). The vagina and urethra were important sites colonized; the rectum was not colonized. Among the isolates, 3 isolates of a new serotype IV/C were seen. It was found that the postinsertion group had double the carriage rate of group B streptococci (4% versus 2%). Chronic inflammatory response to an IUD may enhance the growth of group B streptococci. Overall vaginal carriage rate for normal women in this study was 3%, even with the use of selective media. The urethral carriage rate (3.5%) was slightly higher than the vaginal carriage rate (3%), but in venereal disease clinics very high rate for this site are reported. No group B streptococci could be isolated from the rectum. The high incidence of non-typable strains in nonpregnant women found in this study has been observed previously by some workers yet not by others.^ieng

Immunologic and clinical correlates of bronchial challenge responses to Bermuda grass pollen extracts.

We have studied 26 patients with asthma who had positive skin tests for Bermuda grass pollen antigen (BGP) with history, immunologic assays, and bronchial challenge with BGP. In these patients IgE anti-BGP RAST titers were higher in those with positive, 6.8 +/- 4.4% (mean +/- SEM) compared to those with negative bronchial challenges, 2.7 +/- 0.4% (p less than 0.02). Historical data did not predict bronchial challenge response. IgG4 anti-BGP RAST was not different in patients with positive and negative challenges but was markedly increased, 15.3 +/- 11.9%, in patients who had previously had BGP immunotherapy when compared to untreated patients, 3.6 +/- 5.1% (p less than 0.01). IgE anti-Bermuda grass appears to be the major contributor to susceptibility to BGP bronchial challenge. IgG4 anti-Bermuda grass is apparently unrelated to the sensitivity to challenge but appears to be a significant component of the immunologic response to immunotherapy.

Studies of complement activation and IgG subclass restriction of anti-thyroglobulin.

Using a sensitive radioimmunoassay, it was demonstrated that autoantibodies to human thyroglobulin (hTg) did not activate complement upon interaction with solid phase adsorbed hTg. Since IgG4 immunoglobulins do not activate complement, we studied sera containing large amounts of anti-thyroglobulin (anti-Tg) with a sensitive radioimmunoassay for IgG4 anti-Tg. Antibodies of the IgG4 subclass were detected in the sera of each of the eight patients studied and not in control subjects. Quantitative assays of IgG4 anti-Tg were performed by comparing the removal of anti-Tg and total IgG4 during immunoadsorption of anti-Tg. The contribution of IgG4 anti-Tg antibodies to the total quantity of anti-Tg ranged from 6 to 30%, an amount inadequate to explain the lack of complement activation by anti-Tg.

Complement activation by antibodies to Sm in systemic lupus erythematosus.

An enzyme linked immunosorbent assay was developed to quantitate antibodies to Sm (anti-Sm) and to measure complement activation by anti-Sm in vitro. Anti-Sm in plasma of patients with systemic lupus erythematosus (SLE) were bound to purified Sm bound to polyvinyl chloride microtitre plates and assayed for bound IgG or IgM using enzyme linked anti-gamma or anti-mu. The activation of C4 by anti-Sm was measured by adding diluted normal human serum (complement) to the wells and quantitating the amount of C4 bound to the well surface using (Fab')2 goat anti-C4 followed by enzyme linked rabbit anti-goat IgG. The plasmas of 12 of 36 patients with SLE contained anti-Sm and all 12 activated complement (complement activating anti-Sm). Twenty-eight plasmas containing anti-Sm from 12 patients with SLE were studied. Ten of the 12 patients had anti-Sm of the IgG class whereas two had anti-Sm of both IgG and IgM classes. The amount of C4 activating anti-Sm correlated significantly with the in vivo activation of C4 measured by rocket immunoelectrophoresis for C4d and C4, suggesting that complement activation by anti-Sm is important in vivo.

Activation of the classical pathway of complement by rheumatoid factors. Assessment by radioimmunoassay for C4.

A simple, sensitive solid-phase radioimmunoassay to quantitate the activation of the classical pathway of complement by rheumatoid factor (RF) is described. RF (purified, in serum or synovial fluid) was bound to reduced and alkylated IgG adsorbed to polyvinyl chloride microtiter plates and reacted with diluted normal human serum (complement). The activation and binding of C4 were quantitated with 125I-Fab'2-anti-C4. Purified, polyclonal IgM--RF was 100- to 1,000-fold more effective than purified IgG--RF in activating complement. The amount of complement activation produced by RF in each of the 57 sera and 2 synovial fluid samples correlated directly with the amount of IgM--RF present. The complement activating abilities of polyclonal IgM--RF in the sera of 15 rheumatoid arthritis patients were homogeneous. This novel technique is readily applicable to the investigation of complement activation by RF in disease.

Serodiagnosis of the role of opportunistic bacteria in cases of burn wound sepsis.

In the present study, the antibody titres in the serum of 21 patients with burns were analysed against various Gram-negative organisms, infecting the wounds of these patients. Antibody titre was determined on the first, fourth and tenth day of admission. The rise in antibody titre was correlated with the age of the patient, degree and area of burns and clinical status of the burn wounds.