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K B Waites

Publications and source records attributed to K B Waites.

At least 19 recordsLinked to original sources
PubMed2001

Clones of Streptococcus pneumoniae isolated from nasopharyngeal carriage and invasive disease in young children in central Tennessee.

To determine whether nasopharyngeal carriage isolates of Streptococcus pneumoniae are of the same genetic background as isolates that caused invasive disease in one community, IS1167 and boxA genotypes were obtained for 182 pneumococcal isolates from children living in central Tennessee. The isolates represented 70 combined IS1167-boxA genotypes. The genotypic diversity of the invasive isolates was significantly less than that of the total population (P=.003). Most of the carriage isolates belonged to genotypes unique to carriage, whereas most of the invasive isolates belonged to genotypes common to carriage and disease (P=.02). Monte Carlo simulations showed a greater number of genotypes unique to carriage than can be explained by chance (P<.05 in all cases). Two genotypes were identified by multilocus sequence typing as members of globally disseminated clones, and one such genotype that was strictly carriage in this sample caused disease in other studies. Thus, clones can have different propensities for carriage and invasion.

Bacterial Capsules↗
PubMed2001

Clinical isolates of Streptococcus pneumoniae resistant to levofloxacin contain mutations in both gyrA and parC genes.

Thirty Streptococcus pneumoniae clinical isolates resistant to levofloxacin were analyzed for the quinolone resistance-determining DNA sequences to identify point mutations and were tested for in vitro susceptibility to multiple drug classes. Of these isolates, 29 had mutations in both gyrA and parC genes of DNA gyrase and topoisomerase IV, respectively. In GyrA, an amino acid change from Ser-81-->Phe was detected in 27 isolates and a Glu-85-->Lys change was found in the remaining three. Of the 29 isolates for which ParC data were available, Ser-79-->Tyr or Phe were the predominant mutations observed. MICs for levofloxacin were 4-16 mg/l, whereas those for moxifloxacin were 1-2 mg/l. Twenty-four (80%) isolates were susceptible to erythromycin, 25 (83%) to azithromycin, 26 (87%) to clarithromycin, 27 (90%) to clindamycin, 20 (67%) to penicillin, 21 (70%) to ceftriaxone and 30 (100%) to amoxycillin/clavulanate. These results confirm the presence of double mutations among clinical isolates of S. pneumoniae from diverse geographical regions of North America and also suggest that quinolone resistance may develop independently of resistance to other drug classes.

Amino Acid Substitution↗
PubMed2001

In vitro activity of ABT-773, telithromycin and eight other antimicrobials against erythromycin-resistant Streptococcus pneumoniae respiratory isolates of children.

The activity of the ketolide ABT-773 against 180 erythromycin-resistant Streptococcus pneumoniae obtained from children was compared with telithromycin, azithromycin, clarithromyin, roxithromycin, clindamycin, penicillin, levofloxacin and gatifloxacin. Ketolide MICs were all < or =1 mg/l, with ABT-773 being the most potent of all drugs tested. MIC(90)s for macrolides and azithromycin in mefE+ isolates were 16-32 compared with >128 mg/l for ermB+ isolates. ABT-773 and telithromycin MIC(90)s for mefE+ isolates were 0.125 and 0.5, compared with 0.032 and 0.016 mg/l for ermB+ isolates and 0.5 and 1 mg/l, respectively, for isolates containing both genes. Clindamycin was active against mefE+ but not ermB+ isolates. 155 isolates were resistant to penicillin. All fluoroquinolone MICs were < 1 mg/l. Further studies of ketolides for treatment of paediatric S. pneumoniae infections are warranted.

Anti-Bacterial Agents↗
PubMed2001

Bacteremia after spinal cord injury in initial versus subsequent hospitalizations.

BACKGROUND: Individuals with spinal cord injury (SCI) have a high lifelong risk for systemic infection. For optimal therapy, it is important to characterize the organisms involved in bacteremic episodes and the sites of primary infection. The increase in drug-resistant bacteria in recent years underscores the importance of gathering accurate microbiological information. METHODS: We performed a retrospective study of hospitalized people with SCI using a computerized Microbiology Laboratory Database. We compared the microbiology of bacteremic episodes during initial versus unplanned subsequent hospitalizations. Data were collected on 55 bacteremic episodes in 30 people during initial hospitalization for SCI and 50 episodes in 29 people who were rehospitalized. RESULTS: Among cases in which a site of origin could be identified, the respiratory tract was the origin of the majority of bacteremias during initial hospitalizations, and the urinary tract was the primary origin during rehospitalizations. Polymicrobial bacteremia occurred in 14 of 55 (25%) initial versus 14 of 50 (28%) subsequent hospitalization episodes. The most common pathogens were coagulase-negative staphylococci, followed by Staphylococcus aureus and Enterobacteriaceae. Bacteremia was more common in people with tetraplegia and complete neurologic lesions than in those with paraplegia and incomplete lesions. One person in the rehospitalization group died from complications of bacteremia. All others were successfully treated. CONCLUSIONS: This study describes the frequency and characteristics of bacteremia during initial and subsequent hospitalizations following SCI and examines differences in original sites of infection. This information should be considered when planning infection control measures and empiric antibiotic regimens for patients with SCI.

Adolescent↗
PubMed2001

Antimicrobial activities of gatifloxacin against nosocomial isolates of Stenotrophomonas maltophilia measured by MIC and time-kill studies.

We determined in vitro activities of gatifloxacin and seven other drugs against 100 isolates of Stenotrophomonas maltophilia using the agar gradient diffusion (Etest) method. Percentages of susceptible isolates were as follows: trimethoprim-sulfamethoxazole, 90%; gatifloxacin, 71%; levofloxacin, 57%; ticarcillin-clavulanic acid, 54%; ceftazidime, 49%; ciprofloxacin, 29%; cefepime, 21%; and piperacillin-tazobactam, 20%. Time-kill studies of three isolates indicated that gatifloxacin was bactericidal at times as early as 3 h of incubation when tested at concentrations equivalent to twice the MIC (two isolates) and 4 times the MIC (one isolate).

Anti-Infective Agents↗
PubMed2001

Evaluation of BacT/ALERT system for detection of Mycoplasma hominis in simulated blood cultures.

We used simulated blood cultures inoculated with clinical isolates of Mycoplasma hominis to determine whether liquid media of the BacT/ALERT (Organon Teknika, Durham, N.C.) will support growth of this fastidious organism and whether its presence can generate a positive signal with the instrument. Viability of clinical isolates of M. hominis was maintained for 7 days in BacT/ALERT media, and organisms were able to multiply when 1% gelatin was added to neutralize the mycoplasmastatic effects of the sodium polyanetholsulfonate anticoagulant. Without the addition of gelatin to BacT/ALERT bottles, the mycoplasmas declined in numbers or became completely nonviable. Mycoplasmal growth was further enhanced in BacT/ALERT PF both supplemented with gelatin, arginine, and DNA in comparison to broth with only gelatin added. No BacT/ALERT bottles containing M. hominis in simulated blood cultures were flagged positive by the instrument, despite growth of microorganisms of up to 10(7) CFU/ml after incubation for up to 7 days, suggesting that inadequate CO(2) production or some other mechanism prevents the instrument from recognizing the presence of the organism and its metabolic products. The fastidious cultivation requirements and relatively slow growth of M. hominis warrant that dependence on automated systems and techniques designed to detect conventional bacteria will not be reliable for recovery of M. hominis and that specialized media and incubation conditions designed for optimum cultivation of mycoplasmas should be employed when this organism is suspected on clinical grounds.

Bacteriological Techniques↗
PubMed2001

Direct identification of Mycobacterium avium complex and Mycobacterium gordonae from MB/BacT bottles using AccuProbe.

We evaluated the ability of the AccuProbe (Gen-Probe, San Diego, Calif.) to detect Mycobacterium gordonae and Mycobacterium avium complex directly in liquid medium flagged positive by the MB/BacT (Organon Teknika Corp., Durham, N.C.). Seventy-one bottles from clinical specimens containing M. gordonae and 34 containing M. avium, confirmed by culture, were tested by direct AccuProbe assay for both organisms after additional incubation for > or = 48 h and centrifugation at 4,500 x g for 15 min. Relative light unit (RLU) values were analyzed using the manufacturer's recommended cutoff of 30,000 RLU and a lower cutoff of 10,000 RLU. Using the 30,000 RLU cutoff, 55 of 71 (77.5%) specimens containing M. gordonae yielded positive results, whereas 28 of 34 (82.3%) M. avium complex specimens were correctly identified by direct probe. No specimens shown by culture to contain either M. gordonae or M. avium complex tested positive with the probe for the opposite organism (100% specificity). When the cutoff was lowered to 10,000 RLU, 67 of 71 M. gordonae (94.4%) and 32 of 34 M. avium complex (94.1%) specimens were correctly identified. This difference was significant for M. gordonae (P = 0.004) but not for M. avium complex (P = 0.26) compared to detection using the recommended RLU cutoff. Specificity was 100% for specimens containing M. gordonae that were tested with the M. avium complex probe using the 10,000 RLU cutoff, whereas specificity for specimens containing M. avium complex tested with the M. gordonae probe was 97%. Using a lower RLU cutoff for determining a positive result using the M. gordonae or M. avium complex probes when testing instrument-positive MB/BacT bottles directly will improve sensitivity without substantially compromising specificity.

Bacteriology↗
PubMed2000

Quantitative analysis of Helicobacter pylori infection in a mouse model.

Progress in elucidating the pathogenesis of Helicobacter pylori gastric infection and in developing an H. pylori vaccine will be aided by an animal model in which H. pylori can be reliably detected. To validate the use of the mouse model of H. pylori infection, we determined the susceptibility of three inbred strains of mice (C57BL/6J, C57BL/10J and BALB/c) to two VacA+/CagA+ isolates of H. pylori (SPM326 and M1.16) and determined the effectiveness of microbiological, histological and molecular assays for H. pylori detection. For the detection of H. pylori in inoculated mice, reverse transcriptase-polymerase chain reaction was the most sensitive assay (82%), histological evaluation the next most sensitive (66%) and microbiological evaluation the least sensitive (38%); the assays were equally specific (100%). Of the two H. pylori isolates, M1.16 showed the highest rate of colonization, but SPM326 displayed the highest rate of persistent infection. Among the three mouse strains, C57BL/6J mice showed the highest level of both susceptibility to colonization and persistent infection. Anti-H. pylori antibody responses were induced in all inoculated mice and persisted for up to 8 weeks after H. pylori clearance. These results indicate that inbred mice experimentally infected with H. pylori is a reliable model for human infection, but host susceptibility to colonization and persistence of infection are dependent on the H. pylori isolate and the mouse strain.

Animals↗
PubMed2000

Helicobacter pylori-induced mucosal inflammation is Th1 mediated and exacerbated in IL-4, but not IFN-gamma, gene-deficient mice.

To elucidate the pathogenesis of Helicobacter pylori-associated gastritis, we studied immune responses of C57BL/6J wild-type (WT), SCID, and gene deficient (IFN-gamma-/- and IL-4-/-) mice following infection with a pathogenic isolate of H. pylori (SPM326). During early infection in WT mice, mononuclear and polymorphonuclear cells accumulated in the gastric lamina propria, and the numbers of cells in the inflamed mucosa expressing IFN-gamma, but not IL-4, mRNA rose significantly (p < 0.005), consistent with a local Th1 response. Splenic T cells from the same infected WT mice produced high levels of IFN-gamma, no detectable IL-4, and low amounts of IL-10 following in vitro H. pylori urease stimulation, reflecting a systemic Th1 response. Infected C57BL/6J SCID mice did not develop gastric inflammation despite colonization by many bacteria. Infected C57BL/10J and BALB/c mice also did not develop gastric inflammation and displayed a mixed Th1/Th2 splenic cytokine profile. These data imply a major role for the Th1 cytokine IFN-gamma in H. pylori-associated gastric inflammation in C57BL/6J mice. Compared with WT animals, infected IL-4-/- animals had more severe gastritis and higher levels of IFN-gamma production by urease-stimulated splenocytes (p < 0.01), whereas IFN-gamma-/- mice exhibited no gastric inflammation and higher levels of IL-4 production by stimulated splenocytes. These findings establish C57BL/6J mice as an important model for H. pylori infection and demonstrate that up-regulated production of IFN-gamma, in the absence of the opposing effects of IL-4 (and possibly IL-10), plays a pivotal role in promoting H. pylori-induced mucosal inflammation.

Animals↗
PubMed2000

Antimicrobial resistance in gram-negative bacteria isolated from the urinary tract in community-residing persons with spinal cord injury.

OBJECTIVE: To assess the epidemiology of antimicrobial resistance among community-residing persons with spinal cord injury (SCI). DESIGN: Retrospective analysis of existing data. SETTING: Data were obtained from persons with SCI attending clinic for annual examinations. PARTICIPANTS: Two hundred eighty-seven SCI outpatients. INTERVENTION: None. MAIN OUTCOME MEASURE: Occurrence of bacteriuria with gram-negative organisms demonstrating resistance to antimicrobial agents in 2 or more classes. RESULTS: There were 706 gram-negative isolates from 444 urine specimens. Resistance to drugs in 2 or more classes occurred in 33% of bacterial isolates, but did not significantly increase in frequency among those injured for longer periods or more severely. Significantly higher rates of multidrug-resistant bacteria occurred in specimens from males, younger age group (< or =45 yrs), and persons with indwelling and condom catheters. CONCLUSIONS: Antimicrobial resistance in outpatients with SCI is common and is related to widespread use of specific drugs, type of bladder management, and other host factors.

Adult↗
PubMed2000

Histologic examination of bone marrow core biopsy specimens has limited value in the diagnosis of mycobacterial and fungal infections in patients with the acquired immunodeficiency syndrome.

Bone marrow cultures and biopsy specimens are commonly obtained to rule out disseminated infections, especially in persons with the acquired immunodeficiency syndrome (AIDS) and cytopenias. Using culture as the gold standard, we reviewed 130 consecutive bone marrow cores obtained from 114 AIDS patients along with results of concurrent blood and/or bone marrow aspirate cultures to determine the usefulness of histologic examination for diagnosis of mycobacterial and fungal infections. We also compared the ability of Ziehl-Neelsen, auramine-rhodamine (AR), polyclonal antibody to Mycobacterium bovis (Ab), and Gomori's methenamine silver staining to detect infections. Twenty-seven patients had mycobacterial infection (25 Mycobacterium avium-intracellulare complex cases and two Mycobacterium tuberculosis cases) detected by blood and/or bone marrow cultures. The maximum sensitivity of histology was 50% when the auramine-rhodamine stain and the polyclonal antibody to M bovis were used in combination. The single best stain was auramine-rhodamine, with a sensitivity of 44%, followed by the polyclonal antibody to M bovis (35%). Granulomas were observed in nine cases of mycobacterial infection and did not correlate with the presence of stainable organisms. Of seven patients with positive fungal cultures of bone marrow, four had granulomas and a positive Gomori's methenamine silver stain, one had only a positive stain, and two had neither granulomas nor a diagnostic stain. Overall, granulomas were not sensitive for the detection of infections when culture-proven mycobacterial and fungal cases were evaluated together. We conclude that bone marrow examination has a limited value in the routine evaluation of common opportunistic infections in AIDS patients and recommend that less-invasive tests, such as blood cultures, be obtained initially in most circumstances.

AIDS-Related Opportunistic Infections↗
PubMed1999

Infection during circulatory support with ventricular assist devices.

BACKGROUND: This study is a retrospective analysis of infections in patients supported by ventricular assist devices (VADs) as a bridge to cardiac transplantation. METHODS: Infections were assigned to four classes. Class I were patient-related nonblood infections, class II were blood-borne infections, class III were percutaneous site infections, and class IV were infections of intracorporeal VAD components. RESULTS: The cumulative number and incidence of infections were higher during the early VAD experience than in more recent patients (p < 0.05), although the cumulative number and incidence of class II and IV infections were similar in earlier and later patients. There were 28 serious (ie, class II and IV) infections in 9 patients who died, and 35 serious infections in 11 patients who survived until transplantation. Three of 4 patients with class IV infections died. A larger cumulative number of infections (ie, total class I-IV) was associated with more fungal isolates (p < 0.001) and more class II and IV infections (p < 0.02). Positive fungal cultures were obtained in 16 patients, but there were only 3 class III and 1 class IV fungal isolates. CONCLUSIONS: Infection remains an important problem for patients with VADs. Bloodstream infections (class II) can often be controlled by appropriate therapy. However, intracorporeal device infections (class IV) are associated with substantial morbidity and mortality. Optimal implant techniques together with optimal wound care, appropriate use of prophylactic antibiotics, and avoidance of infection in indwelling catheters remain the most practical means for minimizing the risk of VAD infection.

Adult↗
PubMed1999

Comparison of MicroScan MICroSTREP, PASCO, and Sensititre MIC panels for determining antimicrobial susceptibilities of Streptococcus pneumoniae.

The MicroScan MICroSTREP MIC panel was compared with PASCO and Sensititre systems against 157 isolates of Streptococcus pneumoniae chosen to include penicillin-susceptible, intermediate, and resistant strains. Arbitration testing was performed by microbroth dilution using National Committee for Clinical Laboratory Standards guidelines. Overall essential agreement of 94-97% and categorical agreement of 91-94% with the reference method was achieved for the three systems. There were 8 very major errors (false susceptibility) for PASCO, 10 for Sensititre, and 9 for MICroSTREP; 4 major errors (false resistance) each for PASCO and MICroSTREP, and 6 for Sensititre. Most of these errors occurred with trimethoprim/sulfamethoxazole. Minor errors (susceptible or resistant versus intermediate) totaled 47 for PASCO, 69 for Sensititre, and 53 for MICroSTREP. Minor interpretive errors were most common with penicillin and ceftriaxone. This study showed that all three MIC panels provided interpretive results comparable to one another and to the reference method.

Adult↗
PubMed1999

Effect of oral ciprofloxacin on bacterial flora of perineum, urethra, and lower urinary tract in men with spinal cord injury.

A study was performed in 25 men with spinal cord injuries undergoing intermittent catheterization whose urine had > or = 10(5) bacterial colonies/ml to determine efficacy of ciprofloxacin in eradicating susceptible organisms from urine, urethra, and perineum. Cultures were obtained prior to, during, and 5 to 7 days after administration of 500 mg twice daily for 10 days. Organisms in urine were also present in the urethra and/or perineum in 20 cases. Susceptible bacteria disappeared from urine in all subjects; but at follow-up 12 had cultures positive for ciprofloxacin-resistant Gram-positive cocci, including 1 with methicillin-resistant Staphylococcus aureus (MRSA), and 2 with ciprofloxacin-resistant Acinetobacter sp. Treatment significantly reduced Gram-negative bacilli in perinea and urethras, but ciprofloxacin-susceptible organisms were replaced by resistant staphylococci, including MRSA, enterococci, and Acinetobacter sp. We support use of ciprofloxacin for treatment of urinary tract infections in persons with spinal cord injury, but in view of supercolonization with resistant organisms, the drug should be reserved for symptomatic persons not likely to respond to other oral agents.

Administration, Oral↗
PubMed1999

In vitro susceptibilities of Mycoplasma hominis to six fluoroquinolones as determined by E test.

Twenty isolates of Mycoplasma hominis were tested for their susceptibility to six fluoroquinolones by the E test. The MICs at which 90% of the isolates were inhibited (in micrograms per milliliter) were as follows: sparfloxacin, 0.031; clinafloxacin, moxifloxacin, and trovafloxacin, 0.063; levofloxacin, 0.25; and ciprofloxacin, 0.5. Increasing the amount of inoculum or incubation in CO(2) elevated MICs by </=1 dilution. E tests produce fluoroquinolone MICs comparable to those obtained by agar and microbroth dilution for M. hominis.

Anti-Infective Agents↗
PubMed1999

Comparison of direct inoculation and Copan transport systems for isolation of Neisseria gonorrhoeae from endocervical specimens.

Two commercial swab transport systems, Copan Amies gel agar with and without charcoal (Copan Diagnostics, Corona, Calif.), were compared to direct inoculation onto modified Thayer-Martin medium for detection of Neisseria gonorrhoeae in 1,490 endocervical specimens obtained from women attending a sexually transmitted disease clinic. Copan swabs were held in the transport system for 24 h at room temperature prior to inoculation onto modified Thayer-Martin medium. All cultures were incubated at 35 degrees C in 5% CO(2), and bacteria were identified on the basis of Gram stain, oxidase, and biochemical reactions. Copan Amies gel agar transport system without charcoal detected 77 of 81 (95%) direct inoculation culture-positive specimens, and Copan Amies gel agar transport system with charcoal detected 53 of 56 (95%) directly inoculated culture-positive specimens. Copan Amies gel agar without charcoal inoculated after 6 h supported growth of 56 (98%) positive cultures out of only 55 directly inoculated culture-positive specimens. This study demonstrates that Copan swabs represent a reasonable alternative, providing convenience, low cost, and ease of use while still maintaining a satisfactory recovery rate of N. gonorrhoeae from clinical specimens, if specimens can be inoculated onto selective media within a relatively short time period not involving overnight shipment.

Adult↗
PubMed1999

Detection of Chlamydia trachomatis endocervical infections by ligase chain reaction versus ACCESS Chlamydia antigen assay.

Ligase chain reaction (LCR) was compared with ACCESS immunoassay for detection of chlamydial infections in females. Despite efforts to improve ACCESS performance by evaluation of specimens that were in the test performance "grey zone," LCR remained more sensitive and was less expensive to perform. ACCESS had a sensitivity of 83.9%, a specificity of 99.7%, a positive predictive value of 96.3%, and a negative predictive value of 98.5%.

Antigens, Bacterial↗