Ultrastructure of the flagellar basal body complex of Centipeda periodontii.

The morphology and insertion of the flagellar basal body complex into the cell wall of Centipeda periodontii was studied by electron microscopy of both negatively and positively stained specimens. Freshly harvested cells were examined either after treatment with 0.2% sodium dodecyl sulfate (SDS) for 2 min and negatively stained with phosphotungstic acid, or after treatment according to standard electron microscopy procedures that included positive staining. Small numbers of flagella were dislocated from the cell body after treatment with SDS. The flagella demonstrated an unusual basal body structure: five rings were attached to a rod in a three-ringed (distal) and two-ringed (proximal) patterns; ring diameters produced a distinctive hourglass shape. The cell envelope was typical for gram-negative bacteria with a cytoplasmic membrane and an outer membrane separated by a peptidoglycan layer. Basal body length and cell wall width were in general agreement, approximately 29 nm. Cell wall width exceeded dimensions previously reported for Escherichia coli; this was attributed to an unusually thick peptidoglycan layer.

Laboratory indices of clinical peritonitis: total leukocyte count, microscopy, and microbiologic culture of peritoneal dialysis effluent.

Total leukocyte count, microscopy, and conventional bacteriologic culture (10-ml sediment) of dialysis effluent were assessed for their ability to detect peritonitis in patients on peritoneal dialysis. A total of 73 patients were surveyed over a 17-month period. Laboratory findings included an examination of 1,774 dialysate samples and culture results from blood, wounds, indwelling catheters, and other specimens. Of 90 peritonitis events, 72 were culture positive. Gram-stained films were positive in no more than 14% of the dialysates collected during periods of clinical peritonitis. Factors which adversely affected the microscopic or cultural detection of microorganisms in effluent included the concentration of organisms in dialysate, antibiotic therapy, and growth medium used. Seeding of the peritoneum with organisms originating from other sites of infection or colonization was documented, although infrequent, yet bacteremia secondary to peritonitis was not seen. Because of the frequent isolation of microorganisms from dialysates in the absence of clinical peritonitis, culture-positive findings were a poor predictor of peritonitis without other evidence of infection. Detection of peritonitis by total leukocyte count (without a differential count) of dialysate specimens was adversely affected by the overlap in cell counts between dialysates collected either during or in the absence of peritonitis. This was attributed in part to nonspecific increases in dialysate cell count in the absence of peritonitis and was associated with intermittent dialysis and extraperitoneal infection.

Mycobacterium haemophilum infection in a patient with acquired immune deficiency syndrome.

Mycobacterium haemophilum was isolated from wrist and ankle aspirates as the organism responsible for tenosynovitis in a patient with acquired immune deficiency syndrome. Mycobacterium isolates recovered from synovial fluid were identified as hemin requiring by their failure to grow on subculture unless the medium was supplemented with hemin. M. haemophilum is of low virulence and rarely associated with infections in humans. This is the first documented case of M. haemophilum infection in a patient with acquired immune deficiency syndrome.

Addi-Chek filtration, BACTEC, and 10-ml culture methods for recovery of microorganisms from dialysis effluent during episodes of peritonitis.

The Addi-Chek (filtration; Millipore Corp., Bedford, Mass.) and BACTEC (radiometric detection of growth in culture media; Johnston Laboratories, Inc., Towson, Md.) systems were compared with the 10-ml culture (centrifugation) method for the recovery of microorganisms from peritoneal dialysate collected from patients with clinical evidence of peritonitis and containing greater than or equal to 200 leukocytes per mm3. Both alternate methods were comparable, and results were not significantly different from those of the conventional 10-ml culture method. All systems were adversely affected in their capacity to recover organisms when dialysates had been collected during periods of antimicrobial therapy.

Application of bioluminescent urine screens in a tertiary care facility.

Two adenosine triphosphate (ATP)-detection systems for quantitating bacteriuria, the LUMAC (noncentrifugation method) and MONOLIGHT (centrifugation method) urine screens, were separately evaluated for their capacity to detect bacteriuria in specimens from patients at a tertiary care teaching hospital. Results of each study were compared with the findings of conventional culture. Indices of test efficacy, sensitivity/predictive value for a negative test, were as follows: at greater than or equal to 10(4) CFU/ml--LUMAC 88%/93% and MONOLIGHT 82%/88%; and at greater than or equal to 10(5) CFU/ml--LUMAC 99%/99% and MONOLIGHT 97%/99%. Both systems were satisfactory urine screens for catheterized and midstream urine specimens when used at the traditional level of significance (greater than or equal to 10(5) CFU/ml). An assessment of the MONOLIGHT noncentrifugation protocol demonstrated efficacy of the system to detect significant bacteriuria at greater than or equal to 10(5) CFU/ml. Decreased numbers of false-positive results compared to the centrifugation method were obtained with this assay. False-positive and false-negative results were attributable to threshold sensitivity of the instruments. The presence of somatic cells and yeasts were associated with false-positive results. False-positive results might stem from the inability of conventional culture to recover selected microorganisms. Time and cost analyses of the LUMAC system indicated that significant savings over conventional methodology were not effected.

Leukocyte esterase-nitrite and bioluminescence assays as urine screens.

The 1-min leukocyte esterase (LE)-nitrite test (Chemstrip 9; Biodynamics, Division of Boehringer Mannheim Biochemicals, Indianapolis, Ind.) and a bioluminescence assay (Monolight centrifugation method; Analytical Luminescence Laboratory, Inc., San Diego, Calif.) were tested for their efficacy as urine screens among 453 patients at a tertiary-care teaching hospital. Both methods had the capacity to exclude significant bacteriuria (greater than or equal to 10(5) CFU/ml) when compared with the results of conventional culture methods, with predictive values of 99 and 93%, respectively, for a negative test. Bioluminescence was the more accurate nonculture method used. Sensitivity and specificity values were 97 and 71%, respectively, for bioluminescence, 82 and 60%, respectively, for LE with nitrite, and 72 and 64%, respectively, for LE without nitrite. At reduced levels of bacteriuria less than 10(5) CFU/ml), the sensitivities of LE-nitrite and bioluminescence were decreased but comparable. The addition of protein and blood test results in the Chemstrip 9, along with LE-nitrite as bacteriuria indicators, were unsatisfactory because of the large numbers of false-positive results attributed to protein and blood determinations. LE activity as detected by the LE test was a poor predictor of significant bacteriuria in both male and female patients. The sensitivity (71%) and specificity (57%) of the LE test in male patients were significantly lower than those previously reported and varied with the patient population studied.

Staphylococcus simulans septicemia in a patient with chronic osteomyelitis and pyarthrosis.

Staphylococcus simulans was identified as the etiological agent of osteomyelitis and septic arthritis in an adult male who had sustained a fracture of the fibula and syndesmosis separation which required the installation of orthopedic hardware. Identifying characteristics and antibiograms for this organism, recovered from blood, wound exudate, and deep tissue samples, were determined. Recent evidence has linked slime production (adherence to smooth surfaces) by coagulase-negative staphylococci to infections by these organisms at sites where foreign bodies had been inserted. Tests for adherence showed this S. simulans strain to be a strong slime producer. This is the first reported case of osteomyelitis and septicemia due to S. simulans.

Helical flagellation in Centipeda periodontii, a gram-negative, anaerobic bacillus from periodontitis lesions.

The insertion pattern of flagellation of Centipeda periodontii was determined from electron micrographs of negatively stained cells treated with various detergents to remove their outer cell wall layer(s) selectively. The best results were obtained with 0.2% sodium dodecyl sulphate and a treatment time of 1-2 min. Detergent-treated cells displayed a unique helical pattern of flagellation which we designate as helicotrichous (Gk n. helix, helix + Gk n. thrix, hair). Flagella originated from an electron-dense region approximately 180 nm wide, which spiraled around the cell body. The length of the insertion path averaged 2.6 micron per 360 degrees turn; its periodicity was 2.5 micron. An average of 19 flagella were inserted per 1 micron length of the electron-dense region. The effects of cell division and branching on flagellation were also examined.

Colicins E4, E5, E6 and A and properties of btuB+ colicinogenic transconjugants.

E colicins are those inactive on btuB mutants, which lack the outer membrane protein that adsorbs vitamin B12, E colicins and phage BF23; types E1, E2, E3 and E7 have been defined by the specific immunity of E-colicinogenic strains to the type of E colicin they produce. Further immunity types - E4, E5, E6 - are now described. Shigella sonnei of colicin type 9 makes colicin E4, and Shigella sonnei of types 9A, 12 and 14 make colicin E6 (not colicin E3, as previously supposed). Many local Shigella sonnei isolates make E colicin of a new type - E5. The action of colicins E1 to E7 was (incompletely) blocked by vitamin B12, which also reduced the effect of A colicins (which are weakly active on Escherichia coli K12 btuB indicators). Escherichia coli K 12 given plasmid Co1A-23 by transformation was immune to A colicins but sensitive to colicins E1 to E7. A purported 'colicin E4' was shown to be of class colicin A. Escherichia coli K 12(CloDF13) transformants were immune to colicin E6. A 'cap' of colicin-sensitive indicator bacteria developed over, but not around, killed colonies of btuB+ E-colicinogenic strains, because of adsorption of colicin by non-induced bacteria of the colony. Killed colonies of btuB+ E-colicinogenic strains gave partly discrete lobes of colicin action on indicator lawns, instead of circular zones, apparently as a result of unstable variation in colicin production. The presence of a colicin E4, E5 or E6 plasmid in K12 btuB+ strains made them more sensitive to colicins E2 and E7, as shown by zones of partial translucency surrounding the ordinary colicin zones and by increased titre of colicin E2 and E7 preparations on such indicators.

Escherichia coli K317, formerly used to define colicin group E2, produces colicin E7, is immune to colicin E2, and carries a bacteriophage-restricting conjugative plasmid.

Escherichia coli strain CL137, a K-12 derivative made E colicinogenic by contact with Fredericq's strain K317, was unaffected by colicin E2-P9, but K-12 carrying ColE2-P9 was sensitive to the E colicin made by strains CL137 and K317. This colicin we named E7-K317 because by the test of colicinogenic immunity it differed from colicins E1-K30, E2-P9, and E3-CA38 and from recently recognized colicins termed E4Horak, E5, and E6. Strain K317 as conjugational donor transmitted E7 colicinogeny; about half the E7-colicinogenic transconjugants were immune to colicin E2-P9. A spontaneous variant of CL137 retained E7 colicinogeny but was sensitive to E2 colicins. We attribute the E2 immunity of strain CL137 and some E7-coliconogeic transconjugants to a "colicin-immunity plasmid," ColE2imm-K317, from strain K317. Tra+ E7-colicinogenic transconjugants restricted phage BF23 in the same way as strains carrying ColIb-P9. We attribute Tra+ and restricting ability to a plasmid, pRES-K317, acquired from strain K317, and related to the ColI plasmids.

Salmonella typhimurium mutants of RfaH-phenotype: genetics and antibiotic sensitivities.

Transductional mapping, with phage ES18 or ES18.hl, showed that several mutations causing the RfaH- phenotype (defective formation of galactose I and also of more distal units of the lipopolysaccharide core) were located between metE and pepQ in the Salmonella typhimurium linkage map; the affected locus is designated rfaH. The mutation of one strain of RfaH- phenotype was located elsewhere, at an unidentified rfa locus. Introduction of an F' plasmid containing the metE segment of the Escherichia coli chromosome into several rfaH mutants restored the "smooth" (Rfa+) phenotype. Several rfaH mutations, and that of the phenotypically similar rfa mutant, caused increased sensitivity to bacitracin, polymyxin, novobiocin, nafcillin and oxacillin, as expected if the mutations have no effect on the formation of the part of the lipopolysaccharide core proximal to the galactose units.

Virulence factors of biotypes of Staphylococcus epidermidis from clinical sources.

The biotyping scheme of Baird-Parker was applied to cultures of Staphylococcus epidermidis from patients. In all, 63.6% of 228 cultures belonged to biotype 1, followed by biotypes 4, 3, and 2 in decreasing order of incidence. When classified according to clinical source of isolation, cultures of S. epidermidis were most frequently isolated from urine, with 39.5% of 228 cultures from this source. Each of the four biotypes was distributed throughout all nine catagories of clinical sources. The production of virulence factors was based on the results of three groups of tests: (i) deoxyribonuclease, urease, gelatinase, caseinase, and lysozyme production; (ii) lipolytic activity on the tweens; and (iii) hemolysin production. Enzymatic activity was highest for organisms in biotypes 1, followed by biotypes 3, 4, and 2 in decreasing order. Of the 228 cultures, 76.3% were lysed by lysostaphin. Resistance to antibiotics was highest for tetracycline, ampicillin, and penicillin, with rates of 54.8, 69.3, and 81.6%, respectively. The role of S. epidermidis as an etiological agent was studied by analyzing the laboratory and clinical data of 80 patients selected at random with bacteriuric S. epidermidis. Organisms in biotype 1 were most commonly associated with urinary tract infection. The significance of certain biotypes of S. epidermidis as opportunistic pathogens among compromised hosts in a hospital environment is discussed.