Antibiotic Use and Stewardship Indicators in the First- and Second-Level Hospitals in Zambia: Findings and Implications for the Future

Introduction: There are increasing concerns with growing rates of antimicrobial resistance (AMR) across Africa, including in Zambia, enhanced by inappropriate utilization of antibiotics across the sectors. There is a need in hospitals to document current prescribing patterns via point prevalence surveys (PPS) alongside recognized indicators to improve future use. The findings can subsequently be used to develop and instigate appropriate antimicrobial stewardship programs (ASPs) to improve the quality of future antimicrobial prescribing across Zambia. This includes encouraging the prescribing of 'Access' over 'Watch' and 'Reserve' antibiotics where pertinent. Methods: A PPS was undertaken using the WHO methodology among 10 first- and second-level public hospitals across the 10 provinces of Zambia. A sampling process was used to select the hospitals. Results: The prevalence of antibiotic use among the in-patients was 307/520 (59.0%), with a high rate of empiric prescribing of ceftriaxone at 36.1% of all antibiotics prescribed (193/534). The reason for antibiotic use was recorded in only 15.7% of occasions and directed treatment prescribed in only 3.0% of occasions. Compliance with the national standard treatment guidelines (STGs) was also low at only 27.0% of occasions. Conclusion: High empiric prescribing, limited documentation of the rationale behind antibiotic prescribing, high use of 'Watch' antibiotics, and limited compliance to STGs among surveyed hospitals requires the urgent instigation of ASPs across Zambia to improve future prescribing.

Safety and Efficacy of a Typhoid Conjugate Vaccine in Malawian Children

BACKGROUND

Typhoid fever caused by multidrug-resistant H58 Salmonella Typhi is an increasing public health threat in sub-Saharan Africa.

METHODS

We conducted a phase 3, double-blind trial in Blantyre, Malawi, to assess the efficacy of Vi polysaccharide typhoid conjugate vaccine (Vi-TCV). We randomly assigned children who were between 9 months and 12 years of age, in a 1:1 ratio, to receive a single dose of Vi-TCV or meningococcal capsular group A conjugate (MenA) vaccine. The primary outcome was typhoid fever confirmed by blood culture. We report vaccine efficacy and safety outcomes after 18 to 24 months of follow-up.

RESULTS

The intention-to-treat analysis included 28,130 children, of whom 14,069 were assigned to receive Vi-TCV and 14,061 were assigned to receive the MenA vaccine. Blood culture-confirmed typhoid fever occurred in 12 children in the Vi-TCV group (46.9 cases per 100,000 person-years) and in 62 children in the MenA group (243.2 cases per 100,000 person-years). Overall, the efficacy of Vi-TCV was 80.7% (95% confidence interval [CI], 64.2 to 89.6) in the intention-to-treat analysis and 83.7% (95% CI, 68.1 to 91.6) in the per-protocol analysis. In total, 130 serious adverse events occurred in the first 6 months after vaccination (52 in the Vi-TCV group and 78 in the MenA group), including 6 deaths (all in the MenA group). No serious adverse events were considered by the investigators to be related to vaccination.

CONCLUSIONS

Among Malawian children 9 months to 12 years of age, administration of Vi-TCV resulted in a lower incidence of blood culture-confirmed typhoid fever than the MenA vaccine. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number, NCT03299426.).

Practical Pharmacist-Led Interventions to Improve Antimicrobial Stewardship in Ghana, Tanzania, Uganda and Zambia

The World Health Organisation (WHO) and others have identified, as a priority, the need to improve antimicrobial stewardship (AMS) interventions as part of the effort to tackle antimicrobial resistance (AMR). An international health partnership model, the Commonwealth Partnerships for Antimicrobial Stewardship (CwPAMS) programme, was established between selected countries in Africa (Ghana, Tanzania, Zambia and Uganda) and the UK to support AMS. This was funded by UK aid under the Fleming Fund and managed by the Commonwealth Pharmacists Association (CPA) and Tropical Health and Education Trust (THET). The primary aims were to develop local AMS teams and generate antimicrobial consumption surveillance data, quality improvement initiatives, infection prevention and control (IPC) and education/training to reduce AMR. Education and training were key components in achieving this, with pharmacists taking a lead role in developing and leading AMS interventions. Pharmacist-led interventions in Ghana improved access to national antimicrobial prescribing guidelines via the CwPAMS mobile app and improved compliance with policy from 18% to 70% initially for patients with pneumonia in one outpatient clinic. Capacity development on AMS and IPC were achieved in both Tanzania and Zambia, and a train-the-trainer model on the local production of alcohol hand rub in Uganda and Zambia. The model of pharmacy health partnerships has been identified as a model with great potential to be used in other low and middle income countries (LMICs) to support tackling AMR.

Bacterial-lipopolysaccharide-induced release of lactoferrin from human polymorphonuclear leukocytes: role of monocyte-derived tumor necrosis factor alpha

We have examined the role played by human peripheral blood monocytes in mediating responses of human polymorphonuclear leukocytes (PMN) to bacterial lipopolysaccharide (LPS) in vitro. When incubated with Salmonella typhimurium LPS at 37 degrees C, human PMN suspended in serum-free buffer released the specific granule constituent lactoferrin into the surrounding medium. Release of lactoferrin from PMN varied with the concentration of LPS (1 to 1,000 ng/ml) as well as with the duration of incubation (2 to 60 min) and was not accompanied by significant release of the cytoplasmic enzyme lactate dehydrogenase. LPS-induced release of lactoferrin from PMN was augmented significantly when cell suspensions were supplemented with additional monocytes and lymphocytes. Only monocytes, however, secreted significant amounts of lactoferrin-releasing activity (in a time- and concentration-dependent manner) when incubated separately with LPS. Lactoferrin-releasing activity was heat (80 degrees C for 15 min) labile, eluted after chromatography on Sephadex G-100 with an apparent molecular weight of approximately 60,000, and was inhibited by antibodies to tumor necrosis factor alpha. Thus, LPS-induced noncytotoxic release of lactoferrin from human PMN suspended in serum-free buffer is mediated, at least in part, by tumor necrosis factor alpha derived from contaminating monocytes.

Generation of biologically active, complement-(C5) derived peptides by cathepsin H

The thiol proteinase cathepsin H, isolated and purified from rat liver lysosomes, provokes acute inflammation characterized by the accumulation of polymorphonuclear leukocytes (PMN) when injected intracutaneously into newborn rats. We have examined the possibility that the accumulation of PMN at skin sites injected with cathepsin H is due, in part, to generation locally of C-derived chemotactic factors. We have found that cathepsin H acts in a concentration- and time-dependent fashion in whole human (and rat) EDTA-plasma to generate C5-derived peptides with chemotactic activity for PMN. Chemotactic activity was not generated in EDTA-plasma by either heat-inactivated cathepsin H or by a combination of active enzyme and a thiol proteinase inhibitor isolated from rat epidermis. Cathepsin H also acted in a concentration- and time-dependent fashion on isolated (functionally pure) human C5 to yield chemotactic activity for PMN as well as PMN lysosomal enzyme-releasing activity. Whereas 10 ng/ml cathepsin H generated significant chemotactic activity from isolated C5 (1000 CH50 U/ml), 7 to 10 micrograms/ml were required to generate chemotactic activity in whole EDTA-plasma. Cathepsin H not only was capable of generating biologically active, C5-derived peptides, but also was capable of degrading these peptides. Incubation of either whole EDTA-plasma or isolated C5 with high concentrations of cathepsin H (e.g., 25 micrograms/ml and 100 ng/ml, respectively) caused the rapid appearance of chemotactic activity followed by an equally rapid disappearance. PMN accumulated more rapidly in the skin of newborn rats injected with cathepsin H-treated C5 than in the skin of animals injected with cathepsin H alone. These data suggest that generation by cathepsin H of C-derived chemotactic activity contributes to the ability of this enzyme to induce dermal inflammation.

Generation of biologically active, complement-(C5) derived peptides by cathepsin H

The thiol proteinase cathepsin H, isolated and purified from rat liver lysosomes, provokes acute inflammation characterized by the accumulation of polymorphonuclear leukocytes (PMN) when injected intracutaneously into newborn rats. We have examined the possibility that the accumulation of PMN at skin sites injected with cathepsin H is due, in part, to generation locally of C-derived chemotactic factors. We have found that cathepsin H acts in a concentration- and time-dependent fashion in whole human (and rat) EDTA-plasma to generate C5-derived peptides with chemotactic activity for PMN. Chemotactic activity was not generated in EDTA-plasma by either heat-inactivated cathepsin H or by a combination of active enzyme and a thiol proteinase inhibitor isolated from rat epidermis. Cathepsin H also acted in a concentration- and time-dependent fashion on isolated (functionally pure) human C5 to yield chemotactic activity for PMN as well as PMN lysosomal enzyme-releasing activity. Whereas 10 ng/ml cathepsin H generated significant chemotactic activity from isolated C5 (1000 CH50 U/ml), 7 to 10 micrograms/ml were required to generate chemotactic activity in whole EDTA-plasma. Cathepsin H not only was capable of generating biologically active, C5-derived peptides, but also was capable of degrading these peptides. Incubation of either whole EDTA-plasma or isolated C5 with high concentrations of cathepsin H (e.g., 25 micrograms/ml and 100 ng/ml, respectively) caused the rapid appearance of chemotactic activity followed by an equally rapid disappearance. PMN accumulated more rapidly in the skin of newborn rats injected with cathepsin H-treated C5 than in the skin of animals injected with cathepsin H alone. These data suggest that generation by cathepsin H of C-derived chemotactic activity contributes to the ability of this enzyme to induce dermal inflammation.

Radioimmunoelectrophoresis, a sensitive method for detecting cleavage of the fifth component of human complement (C5)

A method has been developed for detecting cleavage of human C5 in serum and whole blood as a consequence of complement activation. Standard, single-dimension immunoelectrophoresis was performed using as antibody a radioiodinated IgG fraction prepared from a commercially available antiserum to human C5. Autoradiographs developed after radioimmunoelectrophoresis of either normal human serum or functionally pure human C5 revealed only one precipitin band. In contrast, when either zymosan-treated serum or trypsin-treated human C5 were examined with this technique, two additional precipitin bands were detected. One migrated more anodally than native C5 while the other remained at the origin (cathode). Radioimmunoelectrophoresis was significantly more sensitive as an indicator of complement activation in human serum than either measurements of total hemolytic complement or a standard assay for complement (C5)-derived chemotactic activity.

Wheat germ agglutinin specifically inhibits formyl peptide-induced polymorphonuclear leukocyte chemotaxis

Evidence that surface membrane glycoproteins of polymorphonuclear leukocytes (PMN) are involved in stimulus-response coupling prompted us to examine effects on these cells of various plant lectins. We have found that wheat germ agglutinin (WGA) (1.0 microgram/ml) completely, specifically, and irreversibly inhibits directed migration (chemotaxis) of human PMN toward the synthetic peptide, N-formylmethionyl-leucyl-phenylalanine (FMLP) (0.1 to 100 nM). This effect of WGA was not shared by subagglutinating concentrations of either concanavalin A or Bandeirea simplicifolia lectin. In contrast to its effects on FMLP-induced chemotaxis, WGA did not influence other FMLP-induced PMN responses (i.e., selective discharge of lysosomal enzymes from cytochalasin B-treated cells, generation of superoxide anion radical(s). WGA also did not influence PMN chemotactic responses to either the complement-derived peptide, C5a, or the lipoxygenase product, leukotriene B4. Inhibition of FMLP-induced chemotaxis by WGA was not reversed by washing WGA-treated cells, but was reversed (and prevented) by N-acetyl-D-glucosamine (not by N-acetyl-D-galactosamine or mannosamine). WGA did not affect either orientation or stimulated random motility of PMN, and did not interfere with specific binding to PMN of (3H)-FMLP. A derivative of WGA with 10-fold less agglutinating activity for human erythrocytes was prepared by treating the native lectin with cyanogen bromide and formic acid. The derivative also inhibited FMLP-induced PMN chemotaxis specifically and selectively. These data suggest that WGA specifically inhibits FMLP-induced PMN chemotaxis by attaching to N-acetyl-D-glucosamine residues at a locus on the PMN plasma membrane that is distinct from the binding site of the FMLP receptor.

Wheat germ agglutinin specifically inhibits formyl peptide-induced polymorphonuclear leukocyte chemotaxis

Evidence that surface membrane glycoproteins of polymorphonuclear leukocytes (PMN) are involved in stimulus-response coupling prompted us to examine effects on these cells of various plant lectins. We have found that wheat germ agglutinin (WGA) (1.0 microgram/ml) completely, specifically, and irreversibly inhibits directed migration (chemotaxis) of human PMN toward the synthetic peptide, N-formylmethionyl-leucyl-phenylalanine (FMLP) (0.1 to 100 nM). This effect of WGA was not shared by subagglutinating concentrations of either concanavalin A or Bandeirea simplicifolia lectin. In contrast to its effects on FMLP-induced chemotaxis, WGA did not influence other FMLP-induced PMN responses (i.e., selective discharge of lysosomal enzymes from cytochalasin B-treated cells, generation of superoxide anion radical(s). WGA also did not influence PMN chemotactic responses to either the complement-derived peptide, C5a, or the lipoxygenase product, leukotriene B4. Inhibition of FMLP-induced chemotaxis by WGA was not reversed by washing WGA-treated cells, but was reversed (and prevented) by N-acetyl-D-glucosamine (not by N-acetyl-D-galactosamine or mannosamine). WGA did not affect either orientation or stimulated random motility of PMN, and did not interfere with specific binding to PMN of (3H)-FMLP. A derivative of WGA with 10-fold less agglutinating activity for human erythrocytes was prepared by treating the native lectin with cyanogen bromide and formic acid. The derivative also inhibited FMLP-induced PMN chemotaxis specifically and selectively. These data suggest that WGA specifically inhibits FMLP-induced PMN chemotaxis by attaching to N-acetyl-D-glucosamine residues at a locus on the PMN plasma membrane that is distinct from the binding site of the FMLP receptor.

Complement activation by nylon- and polypropylene-looped prosthetic intraocular lenses

Uncomplicated placement of an intraocular lens at the time of routine cataract extraction is associated with a greater inflammatory response than simple lens extraction. We have shown that certain components of prosthetic intraocular lenses are capable of activating the complement system in human serum in such a fashion as to generate peptides capable of mediating acute inflammatory reactions. Normal human serum was incubated with intraocular lenses in vitro and then examined for cleavage products of C3 and C5 and for C5-derived chemotactic activity for human polymorphonuclear leukocytes. Polymethylmethacrylate lenses with nylon and polypropylene loops were found to be capable of causing cleavage of C3 (detected by crossed immunoelectrophoresis) and C5 (detected by single-dimension radioimmunoelectrophoresis) as well as generation of C5-derived chemotactic activity in human serum. Serum incubated with polymethylmethacrylate lenses without loop supports exhibited no such activity. Results of our studies indicate that certain nylon- and polypropylene-looped intraocular lenses are not "inert" biologically and may elicit acute inflammatory reactions.