Involvement of HxuC outer membrane protein in utilization of hemoglobin by Haemophilus influenzae.

Haemophilus influenzae can utilize different protein-bound forms of heme for growth in vitro. A previous study from this laboratory indicated that nontypeable Haemophilus influenzae (NTHI) strain N182 expressed three outer membrane proteins, designated HgbA, HgbB, and HgbC, that bound hemoglobin or hemoglobin-haptoglobin and were encoded by open reading frames (ORFs) that contained a CCAA nucleotide repeat. Testing of mutants expressing the HgbA, HgbB, and HgbC proteins individually revealed that expression of any one of these proteins was sufficient to allow wild-type growth with hemoglobin. In contrast, mutants that expressed only HgbA or HgbC grew significantly better with hemoglobin-haptoglobin than did a mutant expressing only HgbB. Construction of an isogenic hgbA hgbB hgbC mutant revealed that the absence of these three gene products did not affect the ability of NTHI N182 to utilize hemoglobin as a source of heme, although this mutant was severely impaired in its ability to utilize hemoglobin-haptoglobin. The introduction of a tonB mutation into this triple mutant eliminated its ability to utilize hemoglobin, indicating that the pathway for hemoglobin utilization in the absence of HgbA, HgbB, and HgbC involved a TonB-dependent process. Inactivation in this triple mutant of the hxuC gene, which encodes a predicted TonB-dependent outer membrane protein previously shown to be involved in the utilization of free heme, resulted in loss of the ability to utilize hemoglobin. The results of this study reinforce the redundant nature of the heme acquisition systems expressed by H. influenzae.

Fever following total knee arthroplasty.

This study investigated the incidence and clinical significance of postoperative fever in 118 consecutive patients undergoing 141 total knee arthroplasties (TKAs). A postoperative fever was recorded in 63 (66%) of 95 unilateral and 17 (74%) of 23 bilateral TKA patients. Nine of the unilateral and five bilateral TKA patients developed positive clinical or laboratory findings to explain the pyrexia. Unilateral TKA patients who experienced postoperative fever were statistically more likely to have a complication in the immediate postoperative period. None of the surgical variables examined had any predictive value on the incidence of postoperative fever. Aggressive pulmonary toilet, repeated physical examinations, and urine analysis are recommended when evaluating TKA patients with postoperative fever. Fever following TKA was common and was not necessarily a contraindication to discharge.

An analysis of sports knee evaluation instruments.

This study examined four commonly used sports knee evaluation instruments to establish normative data. A total of 91 volunteers who had not sought treatment for knee pain or any other knee complaint at any time in the past underwent a detailed medical history and examination of both of their knees. Three numerical systems (Feagin and Blake Knee Score, Lysholm Knee Score, and the Hospital for Special Surgery Knee Disability Assessment) and one nonnumerical system (the International Knee Documentation Committee Quick Knee Profile) were evaluated. A significant difference in the proportion of knees with excellent/normal ratings was seen among the four evaluation systems (P<.0001): Hospital for Special Surgery Knee Disability Assessment, 99.5%; Feagin and Blake Knee Score, 84.6%; Lysholm Knee Score, 84.1%; and the International Knee Documentation Committee Quick Knee Profile, 50.5%. Results showed that three objective component scores for the International Knee Documentation Quick Knee Profile were significantly lower than all other component scores (P<.05). These components included: overall ligament examination, Lachman, and total AP translation. These data may be useful as a baseline by which investigators studying patients following knee reconstructive procedures have a basis for comparison of their results.

Cost of implanting a cemented versus cementless femoral stem.

Fifty stratified unselected cases of primary uncomplicated total hip arthroplasty performed at the total joint service of a university teaching hospital were examined. In 25 cases, the femoral stem was implanted with cement, and in the other 25, a cementless stem was implanted. For cemented stems, third-generation cement technique was used, including centrifugation. The average cost to the hospital for a cementless stem was $900 greater than for a cemented stem. The total cost to the hospital for accessories used to achieve modern cement technique was over $700. The operative time for implanting a cemented stem averaged 20 minutes longer, which resulted in an additional operating time charge of $270 and an additional anesthesia charge of $100. When these charges are added to the cost of cement and accessories, the actual cost to the hospital for implanting a modern cemented stem was greater than for a corresponding cementless stem.