Growth Of Coagulase-negative Staphylococci Research Articles

180. Duration of Therapy and Clinical Outcomes in Adult Oncology Patients with Uncomplicated Coagulase Negative Staphylococcal Bacteremia

BackgroundAlthough they are often considered contaminants, coagulase negative staphylococci (CoNS) can be pathogens especially in immunocompromised patients. National and local guidelines recommend treatment durations of 7 to 14 days, depending on specific clinical scenarios. The objective was to characterize the duration of treatment for CoNS bacteremia and clinical outcomes at our cancer center. MethodsWe conducted a retrospective chart review of adult patients ≥18 years old with ≥1 blood culture with growth of CoNS between 1/1/17 and 12/31/19 at our cancer center. Patients with complicated CoNS bacteremia and polymicrobial infections were excluded.ResultsAmong 128 patients identified during the study period, 98 met inclusion criteria (Figure 1). Most patients (N= 92; 94%) had a hematologic malignancy as the underlying oncologic diagnosis, and 68 (69%) were hematopoietic stem cell transplant recipients. The median total antibiotic duration was 13 days, and median duration from the date of 1st negative blood culture was 12 days; 29 (30%) patients were treated for a total duration of >14 days (Figure 2). The catheter was retained in 67 (68%) and exchanged in 4 (4%) of the cases. Three (3%) patients had recurrence of bacteremia within 30 days of treatment completion, and 8 (8%) patients were transferred to the ICU within 7 days of the index blood culture. The 30-day crude mortality rate was 10%. The most commonly used antibiotic for treatment was vancomycin (N= 95; 97%), and 32 (34%) patients on vancomycin had an increase in serum creatinine of ≥ 50% from baseline. Five (5%) patients discontinued vancomycin due to nephrotoxicity, and 4 (4%) patients required hemodialysis.Figure 1. Results Overview Among 128 patients identified during the study period, 98 met inclusion criteria. Of those included, 36 had one set of blood cultures that were positive for CoNS and 62 patients had at least two sets of blood cultures that were positive for CoNS.Figure 2. Duration of Antibiotic Treatment We evaluated duration of treatment based on total antibiotic duration and duration from date of 1st negative blood culture. The number of patients is noted above each bar.ConclusionAlthough the majority of patients were treated for ≤14 days for uncomplicated CoNS bacteremia, nearly 1/3 of patients were treated for > 14 days. Recurrent bacteremia was uncommon despite catheter retention in most patients. Relatively high rates of vancomycin associated nephrotoxicity highlight opportunities for antimicrobial stewardship to limit duration of vancomycin therapy among cancer patients with uncomplicated CoNS bacteremia. Disclosures All Authors: No reported disclosures

[Modern views of rehabilitation after septoplasty].

To evaluate the effect of nasal spray Polydexa with phenylephrine on the postoperative period and bacterial contamination in the nasal cavity after septoplasty and inferior turbinectomy. There were 40 people observed, who underwent septoplasty and inferior turbinectomy followed by nasal packing. After removing the tampons from the nasal cavity, the growth of coagulase-negative staphylococci was most often observed in 50%, Enterococcus faecalis - 22.5%, Staphylococcus aureus - 20.0%. In patients who received intranasally Polydexa with phenylephrine drug in the postoperative period, we observed decrease in inflammation in the nasal cavity, an improvement in the quality of life, as well as a significant (p<0.05) decrease in bacterial growth (both in the presence of flora and in intensity growth of microorganisms). The absence of intranasal antibacterial drugs in the scheme of postoperative management of patients contributes to the growth of pathogenic flora, in particular S. aureus.

Hand Microbial Flora of Hospitalized Children at the Beginning of Hospitalization and Before Discharge: A Cross-Sectional Study.

Hospital infections in pediatric units increase the length of hospital stay and the use of antibiotics, and this causes exposure to more procedures. This study was aimed to determine the microorganisms represented in the hand flora of pediatric patients at the beginning of hospitalization and before discharge. The study was designed as a prospective cross-sectional study. This prospective study was performed with 124 pediatric patients. After completion of the admission procedures, an initial sample was taken from the hands of the hospitalized patients. Another sample was taken from the patients just before discharging. Growth of coagulase-negative staphylococcus (CNS) was observed in the culture samples of 28 patients. Cultures from 23 patients showed different microorganisms such as Staphylococcus aureus, Escherichia coli, and S. epidermis. Examination of final discharge cultures showed CNS in 43 patients, S. aureus in 5 patients, E. coli in 8 patients, Acinetobacter baumannii in 11 patients, and Kocuria rhizophila, K. kristinae, Candida spp., Pseudomonas spp., and Enterococcus in 1 patient. The cultures from samples obtained at discharge showed the presence of antibiotic-resistant pathogenic microorganisms causing healthcare associated infection.

High-Level Mupirocin Resistance in Staphylococcus spp. among Health Care Workers in a Tertiary Care Hospital

Background: Nasal carriage of Staphylococcus aureus is very common among health care workers, and treatment with mupirocin is one of the choicest antibiotics available. But with the rampant usage of mupirocin like other antibiotics, the emergence of mupirocin resistance is also on rise. This resistance is both low level as well as high level among the isolated strains. Aim: To screen for the high-level mupirocin resistance among the isolated Staphylococcus strains by Kirby Bauer disk diffusion method. Materials and Methods: A total of 200 clinical isolates were tested for high level mupirocin resistance by disk diffusion method using Himedia disks. Results: Among the 200 nasal swabs, 26 (13%) showed growth of S. aureus, whereas 174 (87%) showed the growth of coagulase negative staphylococcus (CONS) spp. Mupirocin resistance was observed only among CONS spp, which was 15% for low-level mupirocin and 8% for high-level mupirocin resistance. No mupirocin resistance was observed among the Staphylococcus spp. Conclusion: The identification of Mupirocin resistance will guide us to utilize the antibiotic in a judicious way to treat the nasal carriage effectively.

Hematogenous vertebral osteomyelitis associated with intravascular device-associated infections – A retrospective cohort study

IntroductionAim of the study was to investigate the clinical, microbiological, radiological, and treatment characteristics of hematogenous vertebral osteomyelitis originating from infected intravascular devices. Patients and MethodsPatients with secondary hematogenous vertebral osteomyelitis caused by an infected intravascular device were included in this retrospective cohort study. Patients with prior spinal surgery were excluded. Categorical variables were compared using χ2 or Fisher's exact tests and continuous variables using the Mann–Whitney U test. ResultsSixty-seven patients with hematogenous vertebral osteomyelitis were included. Intravenous catheters were the source of infection in 45 patients (67%) and cardiovascular devices in 22 (33%). Fever was present in 21 patients (45%). The main pathogens were coagulase-negative staphylococci, isolated in 42 patients (63%), which grew from blood culture in 52 patients (87%), from vertebral tissue in 29 patients (56%) and from the explanted intravascular device in 18 patients (60%), where it was sampled. Infective endocarditis was diagnosed in 14 of 45 patients (31%), more common with cardiovascular devices than with intravascular catheters (56% versus 15%; P=0.008). ConclusionsIn patients with vertebral osteomyelitis, growth of coagulase-negative staphylococci in blood is highly suggestive for intravascular device-associated infection. Despite absence of systemic or local signs of inflammation at the site of the device, blood cultures should be collected and echocardiography performed in these patients.

Comparison of Demographic and Some Clinical Features of Patients Whose Blood Cultures Revealed Growth of Coagulase Negative Staphylococci and Differentiation Between Infectious Agent and Contaminant was Performed According to the CDC Criteria

Comparison of Demographic and Some Clinical Features of Patients Whose Blood Cultures Revealed Growth of Coagulase Negative Staphylococci and Differentiation Between Infectious Agent and Contaminant was Performed According to the CDC Criteria

Bone transport of the tibia with a motorized intramedullary lengthening nail — a case report

Bone resection and subsequent bone transport and bone lengthening is a well-established treatment for a tibial non-union with shortening (Rozbruch et al. 2008). To our knowledge, this is the first description in the literature of bone transport and subsequent bone lengthening of the tibia only by use of a motorized intramedullary nail. A 53-year-old male twisted his leg while downhill skiing and sustained an OTA classification 43-A2.3 (4) closed fracture of the distal tibia and fibula (Marsh et al. 2007). Both fractures were treated with open reduction and locking plates in January 2009. A non-union developed with loosening of the osteosynthesis, and 7 months after the initial operation the patient was reoperated with bone allograft and exchange of the plates and screws. The non-union did not heal. The patient was referred to our institution 20 months after the first reoperation. At this time, the tibial plate was loose, with broken screws (Figure 1). The tibia had a varus deformity of 16 degrees and was 2.2 cm shortened (Figure 1). The non-union site was tested clinically and found to be loose. Figure 1. Frontal plane varus deformity without sagittal plane deformity of the tibia, with leg-length discrepancy of 2.2 cm in patient with tibial non-union. We operated the patient 24 months after the first reoperation. After removal of all previously inserted implants and screws, except a distal AP screw, the non-union site was found at surgery to be atrophic. The non-union site (3.1 cm bone segment) was resected to vital bone. The fibula was osteotomized at the level of the tibial resection. A proximal percutaneous tibial osteotomy was performed 9 cm from the knee joint line. A custom-made motorized tibial lengthening nail (Fitbone TSA (Tibial Segment Actuator) was inserted. The nail had a length of 35 cm and was capable of 4 cm of bone transport initially and 2 cm of bone lengthening subsequently. The nail had 8 degrees of anterior bending, starting 40 mm from the proximal tip of the nail. The nail was locked with 2 proximal and 2 distal locking screws to the tibia. In addition, a screw was inserted into a sliding hole in the middle part of the tibia, allowing bone transport of the middle tibial segment (Figure 2). A tibio-fibular screw was inserted distally to protect the distal tibio-fibular joint. Acute shortening of the bone defect was not performed. A radiograph taken immediately after surgery showed that 3.1 cm of bone had been resected. Bone transport was initiated 10 days postoperatively at a rate of 1 mm daily (Figure 3). There were no clinical signs of infection and the white blood cell and C-reactive protein levels were normal before surgery. However, biopsies of the resected bone were cultured and showed growth of coagulase-negative staphylococci, which were sensitive to dicloxacillin. Dicloxacillin was therefore administered orally for 3 months. Figure 2. Immediately postoperatively, showing tibial bone gap after bone resection. The bone transport and lengthening nail is inserted in the tibia after proximal tibial osteotomy and distal fibula osteotomy. Figure 3. A. 1 month after surgery. 4 weeks postoperatively, 3.3 mg of recombinant BMP-7 (eptotermin alfa, Osigraft; Stryker) was administered percutaneously to the docking site. A loose proximal locking screw was exchanged at the same surgery and intraoperative fluoroscopy showed that the fibula osteotomy was still loose, allowing lengthening of the fibula. Partial weight bearing was allowed from 2 months postoperatively when the proximal tibia had been lengthened 5 cm (3 cm of bone transport plus 2 cm of leg lengthening). The docking site was united 5 months postoperatively, and full weight bearing was allowed at this time. Healing time for the regenerate was 45 days/cm of bone lengthening. The distal tibio-fibular screw bothered the patient and was removed at 6 months postoperatively. The nail was removed 15 months postoperatively. At the latest follow-up, 18 months after nail insertion and 3 months after nail removal, the patient had no pain or restrictions in daily activities. Motion of the knee and the ankle on the operated side was equal to that on the healthy side. Motion of the knee was from full extension to 140 degrees of flexion and motion of the ankle was from 15 degrees of dorsal flexion to 30 degrees of plantar flexion. An AP radiograph showed no mechanical axis deviation in the operated leg compared to the healthy leg. There was equal leg length. There was a 3-degree varus deformity in the frontal plane. There was no deformity in the sagittal plane on the lateral radiograph. The posterior proximal tibial angle (PPTA) and the anterior distal tibial angle (ADTA) equalled the preoperative values of 78 degrees (PPTA) and 83 degrees (ADTA). There have not been any clinical signs of infection.

Nontuberculous mycobacterial infection after frontalis sling surgery using silicone rod

PurposeThe purpose of this study is to report a case of nontuberculous mycobacterial infection after frontalis sling surgery.MethodA 65-year-old man presented with bilateral painful, erythematous lesions in the brow and upper eyelids. He had a history of frontalis sling surgery for myopathic ptosis 2 years back and all lesions were found localized to the tract of the silicone rod used in the previous frontalis sling surgery.ResultIncision and drainage of the lesions with microbiological analysis revealed significant growth of coagulase negative staphylococcus and Mycobacterium fortuitum. Sensitivity-based antibiotic treatment with intravenous amikacin was started, but poor response necessitated eventual explantation of both silicone rods for relief of symptoms. Culture of the explanted rods revealed similar results of M. fortuitum infection. Five months after the acute presentation, the patient is asymptomatic.ConclusionNontuberculous mycobacterial infection may be a delayed onset complication in frontalis sling surgery using silicone rods.

1368 Stethosopes: Potential Reservoirs for the Spread of Noscocomial Infections

Background: Infants in neonatal intensive care units (NICUs) are at increased risk of nosocomial infection (NI). Aims: To determine stethoscope Staphylococcus (S.) contamination rates & anti-sepsis practices. Methods: Stethoscopes of 12 medical students, 12 NICU physicians and at 12 incubator/cotsides were cultured for S. species (viruses, fungi and other bacteria not assessed). Positive cultures were reported as light, moderate or heavy growth. Students and physicians were surveyed regarding frequency of stethoscope anti-sepsis and charts were reviewed for evidence of NIs. Results: Overall, 22/36 stethoscopes grew S. species. No meticilin resistant S. Aureus was isolated and 11/22 had a light growth of coagulase negative Staphylococci (CONS). There was a moderate/heavy growth CONS from; 3/12 student, 4/12 physician, 2/12 NICU stethoscopes. S. Aureus was isolated from 1 student stethoscope (heavy growth), 1 physician stethoscope (moderate growth) and 0 NICU stethoscopes. 11/12 medical students completed the survey; 1 cleaned the stethoscope often, 8 infrequently and 2 never: surveys were completed by 12/12 physicians; 6 cleaned the stethoscope frequently, 4 often, and 2 infrequently. Self-reported anti-sepsis frequency did not correlate with bacterial growth. NICU bedside stethoscopes were the least contaminated. There were no matching positive blood cultures; in 1 infant CONS was isolated from the stethoscope and from a long-line tip. Conclusions: Stethoscopes represent potential reservoirs of NIs. Contamination of personal stethoscopes with S. species was relatively common; antisepsis should be performed routinely. Individual incubator / cotside stethoscopes were least contaminated and should be used for patients at high risk from NI.

The Efficacy of 5% Povidone-Iodine for 3 Minutes Prior to Cataract Surgery

To evaluate the efficacy of 3 minutes of 5% povidone-iodine for skin and conjunctival antisepsis prior to cataract surgery as recommended by the European Society of Cataract and Refractive Surgeons. A prospective controlled study of 54 patients undergoing unilateral cataract surgery by phacoemulsification was undertaken. The eye undergoing surgery was prepared with 5% povidone-iodine for 3 minutes. The other eye served as control. Swabs were taken from both eyes prior to application of 5% povidone-iodine and 3 minutes after. Proportion of culture-positive swabs, mean number of species, and growth of isolates on culture were compared at different times and between the two groups. Coagulase-negative Staphylococcus (CoNS) was the main species isolated from culture-positive swabs. Use of 5% povidone-iodine for 3 minutes resulted in a statistically significant reduction in proportion of culture-positive swabs (87% vs 30%, p<0.001), mean number of species (0.96-/+0.47 vs 0.30-/+0.46, p<0.001), and growth of CoNS (heavy: 30% vs 0%, moderate: 23% vs 6%, light: 47% vs 94%, p=0.004). No such changes were observed in the control group. Use of 5% povidone-iodine for 3 minutes prior to cataract surgery achieves a significant reduction in organisms such as CoNS from lid and conjunctival flora.

Coagulase negative staphylococci from blood cultures contaminants or pathogens?

Detailed clinical data, underlying conditions, inflammatory indices and microbiological parameters in 60 patients who had pure growth of coagulase negative staphylococci from their blood culture specimens at the University Hospital of the West Indies, Jamaica, were analyzed and the clinical significance of the isolates ascertained using standard criteria. This study was undertaken between April and September 2003. The isolates were true pathogens of bloodstream infections in only 5 of the 60 patients (8.4%). In the vast majority ie 44 of 60 (73.3%) they were mere blood culture contaminants and in 11 (18.3%), the clinical significance could not be ascertained Fifteen of the 44 patients (34%) with contaminating coagulase negative staphylococci were treated with specific anti-staphylococcal antibiotics; 5 (11.4%) with vancomycin. Although there has been a relative increase of coagulase negative staphylococcal infections including bloodstream infections in recent years, the organisms still remain the most common contaminants in blood cultures. Over 70% of isolates were contaminants in this study which is similar to that in a number of such studies in other parts of the world The findings underline the need for careful evaluation of coagulase negative staphylococci isolated from blood cultures before instituting therapy to avoid unnecessary use of antibiotics, especially vancomycin, and the consequent increase of antibiotic resistance in hospitals.

Coagulase-Negative Staphylococcal Sepsis in Neonates

Coagulase-negative staphylococci (CoNS) are the most prevalent pathogens causing late onset sepsis in neonates. They are often multiresistant to antibiotics, and the ability to form biofilm is considered their main virulence determinant. During a 12-year period, we identified 150 neonates having 164 suspected septic episodes with growth of CoNS in blood culture. We examined the relationship between antibiotic resistance, phenotypic biofilm production and genetic determinants for biofilm formation in different CoNS species and their correlation with neonatal inflammatory response. Eighty-five episodes were classified as true sepsis, and 79 episodes of CoNS growth in blood culture were considered contaminations. Sixty-one percent of Staphylococcus epidermidis isolates produced biofilm compared with 26% of CoNS non-epidermidis (P < 0.001). We observed no difference in phenotypic biofilm production or genetic determinants for biofilm formation between invasive isolates and contaminants. C-reactive protein levels as a marker of inflammatory response were higher in CoNS sepsis caused by methicillin and aminoglycoside resistant versus susceptible isolates (P = 0.031). In contrast, there was a significant association between a lower C-reactive protein response and biofilm-positive isolates (P = 0.018). Antibiotic resistance was significantly correlated with biofilm production in S. epidermidis, but not in other CoNS species. CoNS sepsis with biofilm-forming strains was associated with a decreased host inflammatory response, potentially limiting the immune system to counteract the infection. The impact of antibiotic resistance and virulence determinants on clinical outcome of neonatal CoNS sepsis warrants additional clinical studies.

Microbial Changes in Conjunctival Flora with 30-Day Continuous-Wear Silicone Hydrogel Contact Lenses

To determine the effect of 30-day continuous-wear silicone hydrogel contact lenses on the conjunctival flora in asymptomatic wearers. The authors studied 29 eyes of 15 patients wearing Focus NIGHT & DAY silicone hydrogel contact lenses for up to 30 nights of continuous wear. The average age of the patients was 25.54 +/- 8.98 years. Cultures of the inferior cul-de-sac were taken bilaterally from all eyes, before and after lens wear in asymptomatic patients. The isolation and identification of bacteria were made by standard clinical laboratory methods. The number of eyes whose conjunctival cultures were sterile before using the lenses significantly decreased (P = 0.0005), and the number of eyes with a growth of coagulase-negative staphylococci and diphtheroid rods in their conjunctival cultures significantly increased after using these lenses (P = 0.001 and P = 0.031, respectively). Conversely, a statistically significant difference was not found in the number of eyes that carried Propionibacterium acnes and Fusobacterium nucleatum in their conjunctival cultures before and after using the 30-day continuous-wear silicone hydrogel lenses (P = 0.998 and P = 0.488, respectively). The results suggest that the sterility of the conjunctiva significantly decreased after using 30-day continuous-wear silicone hydrogel contact lenses. In addition, the number of bacteria of the normal conjunctival flora significantly increased after the use of these lenses. Contamination by the bacteria of the eyelids may be a possible colonization factor in this study group. Therefore, it is appropriate to examine the patients who wear these lenses more frequently.

Use of incubation time to detection in BACTEC 9240 to distinguish coagulase-negative staphylococcal contamination from infection in pediatric blood cultures.

Growth of coagulase-negative staphylococci (CoNS) in a blood culture indicates infection or contamination. Differentiation may be difficult in pediatric patients from whom only a single blood culture is commonly obtained. We evaluated the use of the incubation time to detection of growth [time to positive (TTP)] of CoNS in a continuously monitored blood culture system (BACTEC Peds/F bottles in BACTEC 9240) to differentiate infection from contamination. Three groups of febrile pediatric patients with blood cultures growing CoNS were identified: Group 1, children with vascular catheter-associated bloodstream infection; Group 2, previously healthy children with a contaminant; Group 3, chronically ill children with a contaminant. The median TTP for blood cultures from the 17 infection episodes, 11 h [mean, 13.2 h; 95% confidence interval (CI), 11.4 to 17.7], was significantly shorter than either the 30 episodes in the previously healthy group with contaminant, median 19 h (mean, 22.7 h; 95% CI 19.5 to 26.2; P < 0.0001) or the 12 episodes in the chronically ill group with contaminant, median 24 h (mean, 35.2 h; 95% CI 17.2 to 53.1; P < 0.0001). A TTP of < or =15 h had a positive predictive value of 84% for diagnosis of infection. A TTP of > or =22 h had a positive predictive value of 87% for diagnosis of contaminant. In our experience the TTP was a useful adjunctive test to determine the clinical significance of isolation of CoNS from a blood culture from a pediatric patient.

Explosive Pleuritis

The objective of the present paper is to describe the clinical and computed tomography features of 'explosive pleuritis', an entity first named by Braman and Donat in 1986, and to propose a case definition. A case report of a previously healthy, 45-year-old man admitted to hospital with acute onset pleuritic chest pain is presented. The patient arrived at the emergency room at 15:00 in mild respiratory distress; the initial chest x-ray revealed a small right lower lobe effusion. The subsequent clinical course in hospital was dramatic. Within 18 h of admission, he developed severe respiratory distress with oxygen desaturation to 83% on room air and dullness of the right lung field. A repeat chest x-ray, taken the morning after admission, revealed complete opacification of the right hemithorax. A computed tomography scan of the thorax demonstrated a massive pleural effusion with compression of pulmonary tissue and mediastinal shift. Pleural fluid biochemical analysis revealed the following concentrations: glucose 3.5 mmol/L, lactate dehydrogenase 1550 U/L, protein 56.98 g/L, amylase 68 U/L and white blood cell count 600 cells/mL. The pleural fluid cultures demonstrated light growth of coagulase-negative staphylococcus and viridans streptococcus, and very light growth of Candida albicans. Cytology was negative for malignant cells. Thoracotomy was performed, which demonstrated a loculated parapneumonic effusion that required decortication. The patient responded favourably to the empirical administration of intravenous levofloxacin and ceftriaxone, and conservative surgical methods in the management of the empyema. This report also discusses the patient's rapidly progressing pleural effusion and offers a potential case definition for explosive pleuritis. Explosive pleuritis is a medical emergency defined by the rapid development of a pleural effusion involving more than 90% of the hemithorax over 24 h, which causes compression of pulmonary tissue and mediastinal shift to the contralateral side.

Growth of coagulase negative staphylococci in peritoneal dialysate fluid. Effect of calcium concentration.

The growth of coagulase negative staphylococci (CNS) in spent and unspent peritoneal dialysate of physiologic (1.25 mmol/l) and standard (1.62 mmol/l) [Ca2++] was studied. Dialysate was prepared by filter sterilization and pH and iCa were measured. Three isolates of CNS grown in unsupplemented Mueller Hinton broth for 18 to 20 hr at 37 degrees C were adjusted to a density of 1.5 x 10(8) CFU/ml. The dialysate (5.4 ml) was inoculated with 0.6 ml of a 10(-4) dilution and then incubated aerobically at 35 degrees C. Plates were made at 0, 6, and 24 hr, and CFU/100 microliters were counted after 24 hr. In a larger study, 10 isolates of CNS were examined. Coagulase negative staphylococcal growth was inhibited by unspent dialysate (P = 0.000; unpaired t-test). Growth was greater in spent physiologic [Ca++] dialysate (iCa -0.76 mmol/l) at 6 hr (P = 0.007) and at 24 hr (P = 0.000) than in standard dialysate (iCa = 0.86 mmol/l) for two of three strains in the pilot study. Similar findings were noted for 4 of 8 strains in the larger study. There was an overall trend for greater growth in physiologic [Ca++] dialysate (P = 0.09). Some strains of CNS grow better in lower [Ca++] dialysate, perhaps representing clinically relevant trophism.

Lack of evidence for increased adherent growth in broth or human serum of clinically significant coagulase-negative staphylococci

The relevance of adherent growth of coagulase-negative staphylococci (CNS) in vitro to their clinical significance is controversial. We have investigated the accumulation on polymer surfaces of clinically significant CNS strains, isolated from blood cultures and intravascular catheter tips, compared with controls. The adherent growth of significant CNS isolates in a microtitre tray assay was not greater than controls, and this finding was repeated when different combinations of target polymer surface, culture medium and incubation atmosphere type were investigated. The surface accumulation of CNS cultured in pooled human serum was poor compared with culture in broth. Whole cell and surface protein profiles of serum grown Staphylococcus epidermidis differed markedly from broth cultured cells. We recommend the use of human body fluids, such as serum, as useful culture media to assess whether potential virulence determinants are likely to be expressed in vivo. The microtitre tray assay of adherent growth is not helpful in determining the virulence of individual CNS isolates.

Peritoneal drainage: an important element in host defence against staphylococcal peritonitis in patients on CAPD.

The growth of Staphylococcus aureus and coagulase-negative staphylococci were studied in fresh and effluent peritoneal dialysate from patients on continuous ambulatory peritoneal dialysis (CAPD). Peritoneal drainage during CAPD removes bacterial contaminants from the peritoneal cavity with an efficiency that depends upon the volume of peritoneal fluid remaining after drainage (residual volume). Combination of our data on the growth of coagulase-negative staphylococci in dialysate with a mathematical model of peritoneal drainage during CAPD shows that a residual volume of less than 800 ml (normal = approximately 400 ml) will prevent survival in the peritoneal fluid. A residual volume of less than 200 ml is required to eliminate S. aureus because of its faster rate of growth in dialysate. Previous work has shown that numbers of macrophages are too few to influence bacterial growth in the peritoneal dialysate. Coagulase-negative staphylococci adhere poorly to mesothelial cells in culture. Survival within the peritoneal cavity during CAPD probably depends on colonization of the PD catheter. Coagulase-negative staphylococcal peritonitis is likely to be localized to areas of the peritoneal membrane in close contact with the PD catheter. S. aureus is able to multiply in the peritoneal dialysate during CAPD and thereby causes generalized peritonitis.

Comparison of blood cultures with corresponding venipuncture site cultures of specimens from hospitalized premature neonates

We compared the presence and identities of isolates from blood culture samples obtained by percutaneous venipuncture with those of commensal skin organisms cultured from respective venipuncture sites after skin cleansing; 677 blood and skin site culture pairs from 488 infants were compared. Organisms grew in 58 blood cultures; nine of these cultures had corresponding venipuncture site cultures that also grew organisms. Forty-two blood culture isolates were coagulase-negative staphylococci; five of these were associated with similar venipuncture site cultures. According to restriction-endonuclease fingerprinting of chromosomal DNA and plasmid analysis, three pairs of blood and venipuncture site cultures were identical and two pairs were different. Thus only 7% (3/42) of coagulase-negative staphylococcal blood isolates were associated with identical contamination at the venipuncture site. We conclude that, if the venipuncture site has been carefully cleansed, the growth of coagulase-negative staphylococci in blood cultures of specimens from premature neonates indicates bacteremia rather than skin contamination in the vast majority of cases.

Unterschiede im Keimspektrum des Konjunktivalsackes vor und nach Tränenwegsspülung

The microbial flora in the conjunctival sac of 30 patients was investigated. Qualitative and quantitative differences before and after irrigation of the lacrimal system were found. In some cases a quantitative increase was registered. In 12 cases conjunctival samples before and after irrigation changed. Negative results before and bacterial growth of coagulase-negative staphylococci after irrigation were found in 4 cases. In 3 cases unfavourable changes were seen. Pseudomonas, Klebsiella and beta-hemolytic streptococci were isolated after irrigation in these cases. In the other cases differences were insignificant. The sense of preoperative irrigation of the lacrimal system is discussed and questioned.