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Infection with human T lymphotropic virus type II (HTLV-II) has been linked to an increased incidence of bacterial pneumonia. To determine whether HTLV-II infection is associated with impaired humoral immune responses, we immunized a cohort of HTLV-II-infected subjects and matched uninfected control subjects with 23-valent pneumococcal polysaccharide and tetanus toxoid vaccines. The pneumococcal polysaccharide vaccine elicited comparable and significant increases in concentrations of IgG against all 5 serotypes tested at 1 and 6 months after immunization in both groups. The avidity and opsonophagocytic functions of the anticapsular IgG were similar. The concentrations of tetanus toxoid-specific IgG also increased comparably and significantly over time in both groups. Thus, HTLV-II-infected persons develop robust humoral responses to potentially protective polysaccharide and protein vaccines.

Capsule-specific secretory IgA (s-IgA) in breast milk may enhance protection against pneumococcal disease in infants. After immunization of 3 lactating mothers with 23-valent polysaccharide vaccine, specific s-IgA, but not IgG, increased by >2-fold in milk of at least 1 subject for 6 of 7 serotypes. The s-IgA was predominantly IgA1, in secretory form, and highly specific with avidity distinct from serum IgA and IgG. Milk whey from 2 immunized women supported dose- and complement-dependent killing of Streptococcus pneumoniae serotypes 19F and 14 by human neutrophils, as did purified s-IgA to serotype 19F. These data reveal that capsule-specific human s-IgA in breast milk can initiate killing of S. pneumoniae, providing proof of concept that vaccine-induced human mucosal s-IgA can support functional bactericidal activity. Determining the biologic role for s-IgA in killing and inhibiting adherence of S. pneumoniae in vivo will contribute to the development of mucosal vaccines against S. pneumoniae.

In East Africa, Streptococcus pneumoniae is a common and serious, but potentially preventable, human immunodeficiency virus type 1 (HIV-1)-associated pathogen. For 54 HIV-1-infected women, baseline levels of capsule-specific antibody to 2 of 4 pneumococcal serotypes were lower than levels in 15 seronegative women (P < .05). After immunization, specific antibody to all 4 serotypes increased in HIV-1-infected and -uninfected women (P < .05). Convalescent levels for 2 of 4 serotypes were greater in seronegative women, but the levels were not different between HIV-1-infected women with (n = 21) or without (n = 33) prior invasive pneumococcal disease. The baseline functional activity to kill S. pneumoniae type 14 was lower in HIV-1-infected than -uninfected women but also rose significantly in all groups after immunization. It is concluded that HIV-1 infection in Kenyan women is associated with decreased levels of natural antibody to selected pneumococcal capsular serotypes, but the vaccine is immunogenic in these patients who are at high risk of invasive pneumococcal disease.

Mutational changes occurring at amino acid codons 84 and 85 located in the gyrA gene of methicillin-resistant Staphylococcus aureus (MRSA) were studied using radiolabeled oligonucleotide probes to examine the incidence of these ciprofloxacin resistance determinants in 30 MRSA isolates from Indiana, Minnesota, and Tennessee. Four separate oligonucleotide probes, one each corresponding to the wild-type sequence, a mutation at codon 84 (nucleotide 251), a mutation at codon 85 (nucleotide 253), and mutations at both, were used to examine the total genomic DNA from each of the 30 isolates, which had been restricted, electrophoresed, and Southern blotted. The probes indicated that 15 of the 28 ciprofloxacin-resistant isolates gave results consistent with a single mutation at codon 84. Four of the 28 ciprofloxacin-resistant strains had results consistent with a mutation at codon 84 and possibly at codon 85. The two ciprofloxacin-sensitive isolates from Tennessee showed homology with the wild-type probe sequence. Five isolates (4, Minnesota; 1, Tennessee) had no homology with any probe. By oligonucleotide probes, ciprofloxacin-resistant MRSA from diverse geographic regions contained similar gyrA mutations at codons 84 or 85 in 19 of 28 ciprofloxacin-resistant isolates.

To examine the possibility of a proton-motive efflux pump for quinolones in highly quinolone-resistant clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), we studied 3H-norfloxacin uptake in two quinolone-resistant and two quinolone-sensitive strains of MRSA whose gyrA region surrounding amino acid codons 84 and 85 had been sequenced. Two strains were related (one sensitive and one resistant) in that both were recovered from a single patient, one before (sensitive) and one after (resistant) ciprofloxacin therapy. Drug uptake was assessed in four separate experiments running triplicate bacterial suspensions with radiolabeled drug added at time = 0. Sampling was performed in 10 min increments up to 50 min by a vacuum filtration method. The ionic uncoupler, carbonyl cyanide m-chlorophenylhydrazone (CCCPH), was added at 40 min to test inhibition of a pump mechanism. The results demonstrated no statistically significant differences in uptake between the sensitive and resistant groups, and the uptake patterns were similar. CCCPH also induced an equivalent surge, or enhanced uptake among these strains, rendering an energy-dependent efflux pump an unlikely contributor to the high levels of resistance seen in our strains. Our findings support parallel studies done on these isolates that implicate mutational changes at amino acid codon 84 and/or codon 85 in the gyrA gene as an explanation for high-level quinolone resistance (MIC to ciprofloxacin greater than or equal to 16 mg/L) in MRSA.

Closed-space, locally neutropaenic infection sites were simulated in rabbits by implanting subcutaneous semipermeable chambers inoculated with 5 X 10(4) cfu/ml of Escherichia coli (one strain), Citrobacter diversus (one strain), Klebsiella pneumoniae (two strains) or Serratia marcescens (two strains). Four hours after inoculation, treatment was begun with amikacin (15 mg/kg), mezlocillin (100 mg/kg), or ceftizoxime (50 mg/kg) alone or in two-drug combinations. Antibiotics were given intramuscularly every 6 h for 16 doses. Chambers were sampled for bacterial counts at the start of therapy, and 20, 44, and 92 h thereafter. Blood and chamber antibiotic levels were determined during the treatment course. In-vivo results were compared to in-vitro tests of inhibition, killing and synergism. Ceftizoxime alone was successful in vivo (greater than 6 log reduction in count) against the three strains of klebsiella and citrobacter, mezlocillin against one serratia strain, and amikacin alone against none of the strains. The best in-vitro correlation was with the minimum inhibitory concentration (MIC) at a high (10(8] inoculum for the beta-lactams and with the anaerobic MIC for amikacin. Among combinations, amikacin plus mezlocillin alone was successful against the three strains of klebsiella and serratia, but neither amikacin nor mezlocillin added to ceftizoxime were more successful than ceftizoxime alone. In-vitro chequerboard synergism was not predictive of in-vivo success. Mezlocillin alone was inactivated in vivo by all the strains except Ser. marcescens, and the E. coli strain inactivated both mezlocillin and ceftizoxime alone and in combination.

The penetration of cephapirin into extravascular spaces of various volumes and ratios of surface area to volume (SA/V) was studied in an in vitro kinetic model. The SA/V ratio was found to be an important determinant of the kinetics of these spaces. The greater the surface area in relation to the volume of the extravascular space, the more closely its kinetics mimicked those of the intravascular space-that is, the higher the absolute peak concentration of drug achieved in the extravascular space, the greater the peak-to-trough fluctuation and the more quickly the peak concentration of drug was reached. Extravascular spaces with similar SA/V ratios demonstrated similar kinetics. Data from various models of extravascular fluid in humans and animals were reviewed, and the kinetics of these extravascular spaces were also found to be determined, at least in part, by the SA/V ratios of the spaces.

Ciprofloxacin, azlocillin, ceftizoxime, and amikacin were studied alone and in combination against six Enterobacteriaceae and six strains of Pseudomonas aeruginosa in an infected chamber model in rabbits simulating a closed space infection. In-vivo results were compared with in-vitro tests of inhibition, killing and synergy. Ciprofloxacin was the most effective single agent, with efficacy against five of the six Enterobacteriaceae when used in low doses, and two of the six pseudomonads when used in high doses. The development of in-vitro resistance to ciprofloxacin was observed during therapy in strains which failed to be eradicated. Ciprofloxacin and azlocillin together was the most effective regimen, with efficacy against eleven of the twelve strains. Synergy, as determined by chequerboard testing, did not correlate with in-vivo outcome. Unlike mezlocillin, azlocillin, ceftizoxime or amikacin, MIC testing of ciprofloxacin was predictive of in-vivo success.