Manual for the Identification of Medical Bacteria.

The global problem of antimicrobial resistance is particularly pressing in developing countries, where the infectious disease burden is high and cost constraints prevent the widespread application of newer, more expensive agents. Gastrointestinal, respiratory, sexually transmitted, and nosocomial infections are leading causes of disease and death in the developing world, and management of all these conditions has been critically compromised by the appearance and rapid spread of resistance. In this first part of the review, we have summarised the present state of resistance in these infections from the available data. Even though surveillance of resistance in many developing countries is suboptimal, the general picture is one of accelerating rates of resistance spurred by antimicrobial misuse and shortfalls in infection control and public health. Reservoirs for resistance may be present in healthy human and animal populations. Considerable economic and health burdens emanate from bacterial resistance, and research is needed to accurately quantify the problem and propose and evaluate practicable solutions. In part II, to be published next month, we will review potential containment strategies that could address this burgeoning problem.

https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(05)70189-4.pdf

Antimicrobial resistance in developing countries. Part I: recent trends and current status

A view on antimicrobial resistance in developing countries and responsible risk factors.

Methicillin-resistant Staphylococcus aureus (MRSA) bacteria have been responsible for substantial morbidity and mortality in hospitals because they usually have multidrug resistance. Some natural products are candidates as new antibiotic substances. In the present study, we investigated the antimicrobial activity of berberine, the main antibacterial substance of Coptidis rhizoma (Coptis chinensis Franch) and Phellodendri cortex (Phellodendron amurense Ruprecht), against clinical isolates of MRSA, and the effects of berberine on the adhesion to MRSA and intracellular invasion into human gingival fibroblasts (HGFs). Berberine showed antimicrobial activity against all tested strains of MRSA. Minimum inhibition concentrations (MICs) of berberine against MRSA ranged from 32 to 128 µg/mL. Ninety percent inhibition of MRSA was obtained with 64 µg/mL or less of berberine. In the checkerboard dilution test, berberine markedly lowered the MICs of ampicillin and oxacillin against MRSA. An additive effect was found b...

Antimicrobial activity of berberine alone and in combination with ampicillin or oxacillin against methicillin-resistant Staphylococcus aureus.

Two natural extracts were loaded within fabricated honey, poly(vinyl alcohol), chitosan nanofibers (HPCS) to develop biocompatible antimicrobial nanofibrous wound dressing. The dried aqueous extract of Cleome droserifolia (CE) and Allium sativum aqueous extract (AE) and their combination were loaded within the HPCS nanofibers in the HPCS-CE, HPCS-AE, and HPCS-AE/CE nanofiber mats, respectively. It was observed that the addition of AE resulted in the least fiber diameter (145 nm), whereas the addition of the AE and CE combination resulted in the least swelling ability and the highest weight loss. In vitro antibacterial testing against Staphylococcus aureus, Escherichia coli, Methicillin-resistant S. aureus (MRSA), and multidrug-resistant Pseudomonas aeruginosa was performed in comparison with the commercial dressing AquacelAg and revealed that the HPCS-AE and HPCS-AE/CE nanofiber mats allowed complete inhibition of S. aureus and the HPCS-AE/CE exhibited mild antibacterial activity against MRSA. A preliminary in vivo study revealed that the developed nanofiber mats enhanced the wound healing process as compared to the untreated control as proved by the enhanced wound closure rates in mice and by the histological examination of the wounds. Moreover, comparison with the commercial dressing Aquacel Ag, the HPCS, and HPCS-AE/CE demonstrated similar effects on the wound healing process, whereas the HPCS/AE allowed an enhanced wound closure rate. Cell culture studies proved the biocompatibility of the developed nanofiber mats in comparison with the commercial Aquacel Ag, which exhibited noticeable cytotoxicity. The developed natural nanofiber mats hold potential as promising biocompatible antibacterial wound dressing.

Honey/Chitosan Nanofiber Wound Dressing Enriched with Allium sativum and Cleome droserifolia: Enhanced Antimicrobial and Wound Healing Activity

The antimicrobial effects of aqueous garlic extract (AGE) against 133 multidrug-resistant gram-positive and gram-negative bacterial isolates, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli, Shigella spp., and Proteus spp., and against 10 Candida spp. were studied. Antibacterial activity of AGE by well-diffusion and macrobroth dilution method was characterized by inhibition zones of 20.2-22.7 mm for gram-positives and 19.8-24.5 mm for gram-negatives and minimum inhibitory concentration (MIC) ranges of 15.6-48.3 mg/mL and 22.9-37.2 mg/mL, respectively. With the exception of P. aeruginosa, the observed disparity in MIC values at 24 and 48 hours was not significant (P >.05) in these isolates. The anticandidal effect of AGE resulted in a growth inhibition zone of 27.4 +/- 3.7 mm with no significant difference (P >.05) in MIC values at 24 and 48 hours, respectively. Minimum fungicidal concentrations were found to be 14.9 and 15.5 mg/mL, respectively, at these incubation periods. Further analysis revealed the antimicrobial efficacy of AGE to be dose and time dependent, producing five distinct time-kill profiles among the isolates tested. The results of this study support the use of garlic in health products and herbal remedies in Nigeria.

/pdf/in-vitro-antimicrobial-properties-of-aqueous-garlic-extract-3swc79akyz.pdf

In Vitro Antimicrobial Properties of Aqueous Garlic Extract Against Multidrug-Resistant Bacteria and Candida Species from Nigeria

Antimicrobial susceptibility of Shigella spp. and Escherichia coli, isolated from diarrhoeal patients in Lagos, was studied from March 1999 to February 2000. Four hundred fifty-nine isolates were identified as shigellae (62) and E. coli (397). Shigella flexneri, S. dysenteriae, S. boydii, and S. sonnei accounted, respectively, for 51.6%, 17.7%, 17.7%, and 13% of the total number of shigellae isolated. Eleven cases of shigellosis occurred in the age group of 0-9 years, 22 cases in the age group of 10-19 years, and 29 cases in the age group of > or = 20 years. Of the 397 E. coli isolates, 11 were enteropathogenic E. coli (EPEC), and 7 of these strains were isolated with shigellae from stools of patients aged 0-9 year(s) (71.4%) and 10-19 years (28.6%). Over 70% of the Shigella isolates were resistant to two or more drugs, including ampicillin and tetracycline. Twenty-one distinct multidrug resistance patterns were observed in these isolates. During 1990-2000, resistance to ampicillin increased from 70% to 90%, co-trimoxazole from 77% to 85%, chloramphenicol from 71% to 77%, streptomycin from 71% to 79%, and nalidixic acid from 0% to 11.3%. Resistance to tetracycline decreased from 89% to 79% but with MIC50 and MIC90 values outside the susceptible range. While resistance to ciprofloxacin and ofloxacin remained nil with MIC50 and MIC90 values of 0.008 and 0.0016 microgram/mL respectively. The results of this study revealed the endemicity of shigellosis with S. flexneri as the predominant serogroup in Lagos. Children and young adults were at a higher risk of severe shigellosis. The results also suggest that ampicillin, tetracycline, co-trimoxazole, and streptomycin should not be used as the first-line drugs in the treatment of shigellosis. Nalidixic acid should still be selectively used for treatment, while ciprofloxacin and ofloxacin can be ideal alternatives.

Epidemiology of shigellosis in Lagos, Nigeria: trends in antimicrobial resistance.

Elevated plasma levels of xanthine oxidase and liver function parameters have been associated with inflammatory events in several human diseases. While xanthine oxidase provides in vitro protection against malaria, its pathophysiological functions in vivo and interactions with liver function parameters remain unclear. This study examined the interactions and plasma levels of xanthine oxidase (XO) and uric acid (UA), catalase (CAT) and liver function parameters GOT, GPT and bilirubin in asymptomatic (n=20), uncomplicated (n=32), and severe (n=18) falciparum malaria children aged 3-13 years. Compared to age-matched control (n=16), significant (p 0.05) correlation with XO, but lower CAT level (13.4-5.4 U/L) with improved correlations (r=-0.53 to -0.91; p 11.0 g/dL. Multivariate analyses further revealed significant (p<0.05) correlations between liver function parameters and xanthine oxidase (r=0.57-0.64) only in the severe malaria group. We conclude that elevated levels of XO and liver enzymes are biochemical features of Plasmodium falciparum parasitaemia in Nigerian children, with both parameters interacting differently to modulate the catalase response in asymptomatic and symptomatic falciparum malaria.

Levels and interactions of plasma xanthine oxidase, catalase and liver function parameters in Nigerian children with Plasmodium falciparum infection.

Pseudomonas aeruginosa has been reported to be a leading cause ofnosocomial infections. Resistance of this notorious bacterium to commonly used antimicrobial agents is becoming an increasing clinical problem and a recognized public health threat because there are limited number of antimicrobial agents including the antipseudomonal penicillins, cephalosporins, carbapenems, aminoglycosides and fluoroquinolones with reliable activity against it. This study was therefore carried out, using Bauer-Kirby method, to determine the antibiotic susceptibility patterns of Pseudomonas aeruginosa isolates from in-patients and out-patients attending the University College Hospital, Ibadan in Nigeria between June 2004 and May 2006. The isolation rate of Pseudomonas aeruginosa in clinical specimens was found to be 16.8% with the highest occurrence of 41.9% in ear swab followed by 39.3% occurrence in wound swab. The susceptibility pattern showed that 78.3% were sensitive to amikacin and 72.0% to ciprofloxacin. The isolates from the in-patients showed higher resistance to all the antibiotics tested than the isolates from the out-patients, most especially amikacin and ciprofloxacin. However, no consistent antibiotic susceptibility pattern could be established for this pathogenic bacterium based on sources. In conclusion, the Pseudomonas aeruginosa species harboured by in-patients showed higher rates of antibiotic resistance than those of the out-patients. Also amikacin and ciprofloxacin were the two antibiotics found to be most potent against this pathogen.

Antibiotic susceptibility patterns of Pseudomonas aeruginosa to available antipseudomonal drugs in Ibadan, Nigeria.

The most important of fluoroquinolones resistance mechanisms is the accumulation of mutations in the bacterial enzymes targeted by fluoroquinolones; DNA gyrase and DNA topoisomerase IV. The effect of gyrase and Topoisomerase IV enzymes mutations on quinolones resistance in clinical Gram negative bacteria in Nigeria was extensively investigated. 115 Gram-negative bacteria of 4 species were analyzed for antimicrobial susceptibility, polymerase chain reaction amplifications of quinolone resistance determining regions, mutation detection using denaturing high-performance liquid chromatography or sequencing. These strains were Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa . Minimum inhibitory concentrations showed that the level of resistance was high with MIC 50 greater than clinical break point for all drugs. 85 of the 115 isolates carried a mutation in QRDRs. Mutations in gyrA were found at positions 83 and 87 of the quinolone resistance determining regions (QRDRs). 4 amino acid substitutions were seen in gyrA including double mutations at codons 83 + 87 while 2 substitutions were seen within parC at codons 80 and 87. All parC mutations were seen in strains which also carried a gyrA mutation. Mutation at codon position 83 with amino acid subtitution of leucine for serine resulted in a higher MIC than substitution to threonine at position 83 or double mutations of serine 83 and asparagine 87. In conclusion, quinolone resistance in clinical Gram negative bacteria in Nigeria is also mediated by accumulation of mutations at QRDR. Key Words: Quinolones, topoisomerase, mutation, bacteria, Nigeria

/pdf/effects-of-gyra-and-parc-mutations-in-quinolones-resistant-4fwwsyiz90.pdf

A Ogunledun

Papers

In Vitro Antimicrobial Properties of Aqueous Garlic Extract Against Multidrug-Resistant Bacteria and Candida Species from Nigeria

Epidemiology of shigellosis in Lagos, Nigeria: trends in antimicrobial resistance.

Levels and interactions of plasma xanthine oxidase, catalase and liver function parameters in Nigerian children with Plasmodium falciparum infection.

Antibiotic susceptibility patterns of Pseudomonas aeruginosa to available antipseudomonal drugs in Ibadan, Nigeria.

Effects of gyrA and parC Mutations in Quinolones Resistant Clinical Gram Negative Bacteria from Nigeria