Development of an antimicrobial susceptibility surveillance system for Neisseria gonorrhoeae in Malawi: comparison of methods.

Susceptibility of Neisseria gonorrhoeae to gentamicin, the primary treatment for gonorrhea in Malawi since 1993, was determined by using agar dilution MICs, E-test MICs, disc diffusion, and clinical cure rate. Agar dilution MICs were slightly higher in 1996 than in 1993 isolates, with a concomitant drop in the clinical cure rate. E-test MICs were substantially lower than agar dilution determinations, with only 77.4% within 1 log2 concentration.

PIP: Gentamicin (240 mg single intramuscular dose) was adopted in 1993 as the treatment of choice for gonorrhea in Malawi, following findings of high-level gonococcal resistance to penicillin, tetracycline, and streptomycin. This study sought to assess the clinical efficacy of gentamicin in the treatment of Neisseria gonorrhoeae 2 years after the onset of its widespread use and to evaluate the potential roles of the disc diffusion and E test in the development of a surveillance system for monitoring antimicrobial susceptibility. 206 consecutive men presenting to a sexually transmitted disease clinic in Lilongwe in 1996 and 198 urethritis patients treated at a hospital in Blantyre during 1992-93 were enrolled. The clinical cure rate for gentamicin treatment of gonorrhea was 91.8% in 1996 compared to 95.0% in 1993. The proportion of highly susceptible isolates declined from 17.2% in 1993 to 9.5% in 1996, but the majority of isolates remained in the moderately susceptible category. The E test yielded substantially lower minimum inhibitory concentrations (MICs) than the standard agar dilution assay, with only 77.4% within 1 log2 concentration. Disc diffusion was not helpful in determining the efficacy of gentamicin, since there was little difference in the range of disc diameters at different MICs as determined by agar dilution. Establishment of an MIC that clearly shows resistance to gentamicin was not possible. These findings suggest that the agar dilution assay remains the method of choice for MIC determination, although the less expensive E test may be capable of monitoring antibiotic efficacy under field conditions.

Eradication of nasopharyngeal carriage of Neisseria meningitidis in children and adults in rural Africa: a comparison of ciprofloxacin and rifampicin.

A randomized comparative study of rifampicin and ciprofloxacin for eradicating nasopharyngeal carriage of meningococci was undertaken in Malawi. Of 1878 contacts of persons with meningococcal meningitis, 1875 were evaluatable for safety and efficacy of the drugs. Rifampicin was given to 836 contacts, ciprofloxacin to 711, and ceftriaxone to 328 (children < 2 years old or pregnant or lactating women). One and 2 weeks after therapy, side effects in those given rifampicin and ciprofloxacin were not significantly different. In the ciprofloxacin group, with 470 subjects < 18 years old, only one event (mild abdominal pain) occurred that was related to the drug. Nasopharyngeal carriage was detected in 88 (10.5%) of those given rifampicin, 79 (11.1%) given ciprofloxacin, and 41 (12.5%) given ceftriaxone. Eradication rates after 1 and 2 weeks of treatment, respectively, were 96.5% and 97.7% for rifampicin, 88.6% and 91.1% for ciprofloxacin, and 95.1% and 97.6% for ceftriaxone. Ciprofloxacin provides a safe and effective alternative to rifampicin for eradication of meningococcal carriage in children 2-18 years old.

Meningococcal disease in Malawi: studies on the genetic relatedness of the bacteria.

Seventy-seven meningococci, isolated from patients and carriers during a large epidemic of meningococcal meningitis in Malawi, were characterized in terms of antimicrobial susceptibility, plasmid content and multi-locus enzyme electrophoresis (MLEE). All the isolates were sensitive to chloramphenicol but six had high enough minimum inhibitory concentrations of penicillin (> or = 2 mg/litre) to render them clinically resistant. Only one isolate was sensitive to sulphonamides but all the isolates were sensitive to rifampicin and ciprofloxacin, two drugs that would be suitable alternatives in prophylaxis. None of the isolates carried plasmids. MLEE indicated that 32 (80%) of the cerebrospinal fluid isolates and 22 (69%) of those from carriers were closely related genetically (in two electropherotypes that differed at only one allele). The Malawian group A meningococci differed from three Ethiopian isolates by two or three alleles, indicating that direct spread from the sub-Saharan meningitis belt to Malawi was unlikely.

Helicobacter pyrlori in Malawi, central Africa.

A total of 160 adult Malawians with epigastric pain for longer than 2 weeks was investigated by endoscopy and serologically for evidence of infection with Helicobacter pylori. The organism was demonstrated histologically and/or by culture in 141 (88%) patients. With histological means and/or culture as the 'gold standard', the histological technique was 100% sensitive while culture was only 81% sensitive. All isolates tested were sensitive to amoxycillin and tetracycline; 74% were resistant to metronidazole. Endoscopic findings were normal in 104 (65%) patients (86.5% H. pylori positive). Evidence of duodenal ulcer was found in 41 (25%) patients (95% H. pylori positive). Histologically, gastritis was common, severe gastritis being associated with increased colonisation by H. pylori. Two kinds of urease test were found to be 100% specific for the presence of H. pylori. The sensitivity of the serological test (Helico-G test) was 98% but its specificity was only 27%. These results provide important background information for planned therapeutic studies in patients with upper gastro-intestinal disease in Malawi.

Latex particle agglutination tests as an adjunct to the diagnosis of bacterial meningitis: a study from Malawi.

A prospective study using a Latex particle agglutination test for the detection of bacterial antigens in CSF has been carried out in 91 patients in Kamuzu Central Hospital, Malawi. The antigens sought were those of Streptococcus pneumoniae, Haemophilus influenzae b, Neisseria meningitidis B/E. coli K1, and Neisseria meningitidis A,C,Y,W 135. Forty-one patients had proven bacterial meningitis, two had tuberculous meningitis, 39 had cerebral malaria, four had aseptic meningitis and five had convulsions. The sensitivity and specificity of the tests (Str. pneumoniae, 88% and 100%, H. influenzae b, 87% and 96%; N. meningitidis A,C,Y,W 135, 100% and 100%; and N. meningitidis B, 100% and 98%) were as good as those reported from developed countries. Unlike in some other parts of Africa, group B meningococci seem to predominate in cases of meningococcal meningitis in Malawi.

C-reactive protein and bacterial meningitis.

We have studied prospectively the C-reactive protein values in the cerebrospinal fluid of 54 patients with bacterial meningitis, tuberculous meningitis, and severe malarial infection and convulsions without infections of the central nervous system. CSF CRP above 1 mg/l was observed in 23 out of 28 patients with bacterial meningitis (sensitivity of 82%). The specificity was 73% at the 1 mg/l level. Five out of 19 patients with severe malarial infection had CSF CRP levels above 1 mg/l. Two patients with TB meningitis were also studied. Both of them had CSF CRP above 1 mg/l. Five patients with febrile convulsions or sepsis without meningitis had CSF CRP below 1 mg/l. It is concluded that CSF CRP would not be used as a useful discriminatory test in areas where malaria and TB meningitis are common.

Bacterial meningitis in KCH; Lilongwe

A study of epidemiological patterns of bacterial meningitis in Lilongwe using laboratory records from the period 1983-1986 and clinical records of patients admitted to Kamuzu Central Hospital