Trends in rotavirus from 2001 to 2015 in two paediatric hospitals in Atlanta, Georgia.

We compared rotavirus detection patterns before (2001-2006) and after (2008-2015) rotavirus vaccine introduction. We also compared rotavirus detection patterns in odd (2009, 2011, 2013, 2015) and even (2008, 2010, 2012, 2014) years post-vaccine separately. Results of stool rotavirus antigen testing from inpatient, outpatient and emergency department encounters from July 2000 to July 2015 at two paediatric hospital laboratories in Atlanta, Georgia were reviewed. Post-vaccine, rotavirus detection declined (30.2% vs. 13.7% (overall 54.6% decline, P <0.001)), occurred more frequently outside the rotavirus season (19.8% vs. 3.5%; P < 0.001), and was more common among older children (26 vs. 13 median months of age; P < 0.001). During odd years post-vaccine, rotavirus detection was significantly higher than even years (20.2% vs. 6.4%; P < 0.001). Rotavirus detection declined substantially and developed a biennial pattern in the post-vaccine era. The intensity and temporality of rotavirus detection in odd years post-vaccine resembled that observed pre-vaccine, although considerably reduced in magnitude.

Evaluation of an Immunochromatographic Assay for Rapid Detection of Penicillin-Binding Protein 2a in Human and Animal Staphylococcus intermedius Group, Staphylococcus lugdunensis, and Staphylococcus schleiferi Clinical Isolates.

The performance of a rapid penicillin-binding protein 2a (PBP2a) detection assay, the Alere PBP2a culture colony test, was evaluated for identification of PBP2a-mediated beta-lactam resistance in human and animal clinical isolates of Staphylococcus intermedius group, Staphylococcus lugdunensis, and Staphylococcus schleiferi. The assay was sensitive and specific, with all PBP2a-negative and PBP2a-positive strains testing negative and positive, respectively.

TechLab and alexon Giardia enzyme-linked immunosorbent assay kits detect cyst wall protein 1.

A Giardia lamblia antigen detected by the TechLab Giardia Test (TechLab, Inc., Blacksburg, Va.) and the Alexon ProSpecT Giardia microplate assay (Alexon, Inc., Sunnyvale, Calif.) was purified by immunoaffinity chromatography from supernatant fluids of encystment cultures. Two major proteins (Mr 22,000 and 26,000) were observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Coomassie staining that did not resemble the GSA65 antigen reportedly detected by the Alexon test. These proteins reacted intensely with the monoclonal antibodies used in both commercial enzyme-linked immunosorbent assays (ELISAs). Both proteins had identical N-terminal amino acid sequences and were identified as cyst wall protein 1 (CWP1). The 26-kDa form appeared early during encystment followed by the appearance of the 22-kDa form. Recombinant CWP1 (Mr 26,000) was strongly positive in both commercial tests. CWP1 was stable in human stool specimens, resistant to degradation by proteases and N- and O-glycanases, and unaffected by oxidation with sodium periodate. Two minor proteins with Mrs of 32,000 and 39,000 were detected in CWP1 preparations by using a sensitive fluorescent protein stain. Both were identified as CWP2, and neither reacted with the monoclonal antibodies from the commercial tests. We analyzed 535 stool specimens for CWP1 by using both commercial ELISAs and resolved discrepant results by using routine ova and parasite examination (O&P) and on immunofluorescence antibody assay. The presence of CWP1 correlated well between both ELISAs (98.7% correlation). Our results demonstrate that both commercial ELISAs detect CWP1, which is a useful diagnostic marker because it is highly stable, is secreted in large amounts by encysting trophozoites, and correlates well with O&P.

Multicenter comparison of BACTEC 9050 and BACTEC 9240 blood culture systems.

The overall recovery of organisms and time to detection with the BACTEC 9050 and BACTEC 9240 systems were compared in a multicenter evaluation. In the first phase of the study, a total of 4,383 compliant aerobic (Plus Aerobic/F) blood culture sets were processed. There was no significant difference in the recovery of individual groups of organisms with the two systems, with the exception of Streptococcus pneumoniae which was isolated more frequently with BACTEC 9050. False-positive signals occurred more often with BACTEC 9240 (58 cultures) than with BACTEC 9050 (43 cultures), but false-negative cultures were uncommon with both systems (3 cultures for each system). Time to detection of positive cultures of clinically significant organisms was essentially the same with both instruments. In the second phase of the study, 2,431 compliant anaerobic (Plus Anaerobic/F) blood culture sets were processed. There was no significant difference in the recovery of organisms with BACTEC 9050 compared with BACTEC 9240. Significantly (P < 0.03) more false-positive signals occurred with BACTEC 9240 (15 cultures) than with BACTEC 9050 (4 cultures). Likewise, more false-negative cultures occurred with BACTEC 9240 (11 cultures) than with BACTEC 9050 (8 cultures). Time to detection of positive cultures of clinically significant organisms was essentially the same with both systems with the exception of anaerobes (N = 10), which were recovered earlier (P < 0.01) with BACTEC 9240 (35.0 h) than with BACTEC 9050 (61.4 h).

Will the real agent of cat-scratch disease please stand up?

Cat-scratch disease has been recognized since 1889 in association with the oculoglandular syndrome of Parinaud. The epidemiologic association with cats was first made in 1931 and further substantiated throughout the years, refining the interaction predominantly to kittens. Putative infectious agents have included numerous species of bacteria, chlamydiae, and viruses. The cultivation of Afipia spp. in the late 1980s appeared to answer the mystery of the identity of the agent. However, even more recent analysis, which has combined traditional microbiology, molecular methods, and additional epidemiology, has demonstrated that Bartonella (Rochalimaea) henselae is the definitive agent of cat-scratch disease. Our understanding of the pathogenesis of cat-scratch disease and other diseases caused by Bartonella species is incomplete and the spectrum of diseases continues to emerge. We review historic and modern efforts to understand the etiology of cat-scratch disease and related syndromes.

Multicenter clinical evaluation of a continuous monitoring blood culture system using fluorescent-sensor technology (BACTEC 9240).

The BACTEC 9240 (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) is a new continuous-monitoring blood culture system that uses internal, fluorescent-CO2 sensors. In a multicenter clinical trial, organism yield and times to detection with the prototype BACTEC 9240 system were compared with those of the BACTEC NR 660 system. Equal volumes of blood were inoculated into the bottles included in the study blood culture sets (aerobic and anaerobic 9240 and NR6A and NR7A bottles). A total of 9,391 aerobic and 8,951 anaerobic bottle pairs were inoculated with 9,801 blood specimens. A total of 587 clinically significant positive blood cultures and 415 cases of sepsis were studied. The standard 9240 aerobic bottle detected significantly more Staphylococcus aureus (P < 0.05), coagulase-negative staphylococci (P < 0.01), and total microorganisms (P < 0.001) than the NR6A bottle. The standard 9240 anaerobic bottle detected significantly more coagulase-negative staphylococci (P < 0.001), members of the family Enterobacteriaceae (P < 0.01), and total microorganisms (P < 0.001) than the NR7A bottle. A total of 420 positive cultures were detected in both systems; for 284, the time to detection was equivalent with both systems (within 12 h); for 123, the 9240 system was faster; and for 13, the NR 660 system was faster (P < 0.001). The average times to detection for the 9240 and the NR 660 systems were 20.2 and 27.5 h, respectively. Ninety-nine cultures were positive only in the 9240 system, and 68 cultures were positive only in the NR 660 system (P < 0.02). The 9240 system also detected significantly more episodes of bacteremia (P < 0.001). The false-positive rates for the 9240 and NR 660 systems were 2.2 and 2.3%, respectively. The false-negative rates for the two systems after 5 days of incubation did not differ significantly. The contamination rates for the 9240 and NR 660 systems were 1.9 and 1.5%, respectively (P < 0.05). In conclusion, the prototype 9240 system detected more clinically significant positive blood cultures and did so sooner than the NR 660 system, with the additional advantages of full automation, continuous monitoring, and noninvasive sampling.

Haemophilus influenzae resistance in a community hospital.

We prospectively tabulated all isolates of Haemophilus influenzae at DeKalb Medical Center from 1987 through 1989 to assess the occurrence of antibiotic resistance in patients of different ages. Of 325 total strains isolated, 24% produced beta-lactamase, rendering them resistant to ampicillin and amoxicillin. Antibiotic resistance was as common in patients older than age 60 (24%) as in younger patients (23%). Sensitivity testing by disk diffusion and microdilution techniques on 71 isolates (37 beta-lactamase-positive) showed uniform susceptibility to cefuroxime, cefotaxime, amoxicillin/clavulanate, cefaclor, and chloramphenicol, but three beta-lactamase-positive isolates were resistant to trimethoprim/sulfamethoxazole. The high rate of ampicillin resistance noted in elderly patients has implications for the choice of antimicrobial therapy for these infections.

Susceptibility of Propionibacterium acnes clinical isolates to 22 antimicrobial agents.

Susceptibilities of 104 Propionibacterium acnes isolates to each of 22 antimicrobial agents was evaluated by broth microdilution. These isolates were susceptible to all of the test agents except metronidazole. N-Formimidoyl thienamycin, a penem coded Sch 29482, and penicillin ranked first, second, and third, respectively, in activity and were significantly more active than other penicillins, cephalosporins, tetracyclines, clindamycin, or chloramphenicol.

Description of a polyvalent conjugate and a new serogroup of Bacteroides melaninogenicus by fluorescent antibody staining.

A polyvalent conjugate (fluorescein isothiocyanate-labeled antibody reagent) containing serogroups A, B, and C conjugates was prepared. This polyvalent conjugate gave a positive fluorescent antibody (FA) stain with 49 stains of Bacteroides melaninogenicus representing serogroups A, B, and C. When additional strains (92 strains) of the three subspecies of B. melaninogenicus were examined by the FA stain, with A, B, and C, and polyvalent conjugates, nine strains of B. melaninogenicus subsp. intermedius failed to give a positive stain with any conjugate. Therefore, an FA conjugate was prepared with the antiserum to one of these strains (532-70A); all nine strains stained positively with this conjugate. These nine strains were biochemically characteristic of B. melaninogenicus subsp. intermedius; thus, these strains were designated as a new serogroup, serogroup C-1. A new polyvalent conjugate containing serogroups A, B, C, and C-1 was prepared. This polyvalent conjugate stained positively with 23 representative strains from serogroups A, B, C, and C-1. The new conjugates failed to stain positively with other anaerobes and aerobes tested. The four individual conjugates, as well as the polyvalent conjugate, may be used for a more rapid identification of B. melaninogenicus than is possible by biochemical testing.